1
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Halliwell JA, Martin-Gonzalez J, Hashim A, Dahl JA, Hoffmann ER, Lerdrup M. Sex-specific DNA-replication in the early mammalian embryo. Nat Commun 2024; 15:6323. [PMID: 39060312 PMCID: PMC11282264 DOI: 10.1038/s41467-024-50727-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: 08/31/2023] [Accepted: 07/18/2024] [Indexed: 07/28/2024] Open
Abstract
The timing of DNA replication in mammals is crucial for minimizing errors and influenced by genome usage and chromatin states. Replication timing in the newly formed mammalian embryo remains poorly understood. Here, we have investigated replication timing in mouse zygotes and 2-cell embryos, revealing that zygotes lack a conventional replication timing program, which then emerges in 2-cell embryos. This program differs from embryonic stem cells and generally correlates with transcription and genome compartmentalization of both parental genomes. However, consistent and systematic differences existed between the replication timing of the two parental genomes, including considerably later replication of maternal pericentromeric regions compared to paternal counterparts. Moreover, maternal chromatin modified by Polycomb Repressive Complexes in the oocyte, undergoes early replication, despite belonging to the typically late-replicating B-compartment of the genome. This atypical and asynchronous replication of the two parental genomes may advance our understanding of replication stress in early human embryos and trigger strategies to reduce errors and aneuploidies.
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Affiliation(s)
- Jason Alexander Halliwell
- DNRF Center for Chromosome Stability, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Javier Martin-Gonzalez
- Core Facility for Transgenic Mice, Department of Experimental Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Adnan Hashim
- Department of Microbiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Centre for Embryology and Healthy Development, University of Oslo, Oslo, Norway
| | - John Arne Dahl
- Department of Microbiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Centre for Embryology and Healthy Development, University of Oslo, Oslo, Norway
| | - Eva R Hoffmann
- DNRF Center for Chromosome Stability, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Mads Lerdrup
- DNRF Center for Chromosome Stability, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
- Centre for Embryology and Healthy Development, University of Oslo, Oslo, Norway.
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2
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Dietzen M, Zhai H, Lucas O, Pich O, Barrington C, Lu WT, Ward S, Guo Y, Hynds RE, Zaccaria S, Swanton C, McGranahan N, Kanu N. Replication timing alterations are associated with mutation acquisition during breast and lung cancer evolution. Nat Commun 2024; 15:6039. [PMID: 39019871 PMCID: PMC11255325 DOI: 10.1038/s41467-024-50107-4] [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: 01/07/2024] [Accepted: 07/01/2024] [Indexed: 07/19/2024] Open
Abstract
During each cell cycle, the process of DNA replication timing is tightly regulated to ensure the accurate duplication of the genome. The extent and significance of alterations in this process during malignant transformation have not been extensively explored. Here, we assess the impact of altered replication timing (ART) on cancer evolution by analysing replication-timing sequencing of cancer and normal cell lines and 952 whole-genome sequenced lung and breast tumours. We find that 6%-18% of the cancer genome exhibits ART, with regions with a change from early to late replication displaying an increased mutation rate and distinct mutational signatures. Whereas regions changing from late to early replication contain genes with increased expression and present a preponderance of APOBEC3-mediated mutation clusters and associated driver mutations. We demonstrate that ART occurs relatively early during cancer evolution and that ART may have a stronger correlation with mutation acquisition than alterations in chromatin structure.
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Affiliation(s)
- Michelle Dietzen
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK
- Cancer Genome Evolution Research Group, Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London, UK
| | - Haoran Zhai
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London, UK
| | - Olivia Lucas
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London, UK
- Computational Cancer Genomics Research Group, University College London Cancer Institute, London, UK
- Department of Oncology, University College London Hospitals, London, UK
| | - Oriol Pich
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London, UK
| | - Christopher Barrington
- Bioinformatics and Biostatistics Science Technology Platform, The Francis Crick Institute, London, UK
| | - Wei-Ting Lu
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London, UK
| | - Sophia Ward
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London, UK
- Advanced Sequencing Facility, The Francis Crick Institute, London, UK
| | - Yanping Guo
- CRUK Flow Cytometry Translational Technology Platform, UCL Cancer Institute, London, UK
| | - Robert E Hynds
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London, UK
| | - Simone Zaccaria
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK
- Computational Cancer Genomics Research Group, University College London Cancer Institute, London, UK
| | - Charles Swanton
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London, UK
- Department of Oncology, University College London Hospitals, London, UK
| | - Nicholas McGranahan
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK.
- Cancer Genome Evolution Research Group, Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK.
| | - Nnennaya Kanu
- Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London, UK.
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London, UK.
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3
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Torres MC, Rebok A, Sun D, Spratt TE. Activity of DNA polymerase κ across the genome in human fibroblasts. Proc Natl Acad Sci U S A 2024; 121:e2403130121. [PMID: 38950369 PMCID: PMC11252913 DOI: 10.1073/pnas.2403130121] [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: 03/04/2024] [Accepted: 05/17/2024] [Indexed: 07/03/2024] Open
Abstract
DNA polymerase κ (Polκ) is a specialized polymerase that has multiple cellular roles such as translesion DNA synthesis, replication of repetitive sequences, and nucleotide excision repair. We have developed a method for capturing DNA synthesized by Polκ utilizing a Polκ-specific substrate, N2-(4-ethynylbenzyl)-2'-deoxyguanosine (EBndG). After shearing of the DNA into 200 to 500 bp lengths, the EBndG-containing DNA was covalently bound to biotin using the Cu(I)-catalyzed alkyne-azide cycloaddition reaction and isolated with streptavidin beads. Isolated DNA was then ligated to adaptors, followed by PCR amplification and next-generation sequencing to generate genome-wide repair maps. We have termed this method polymerase κ sequencing. Here, we present the human genome maps for Polκ activity in an undamaged cell line. We found that Polκ activity was enhanced in GC-rich regions, euchromatin regions, the promoter of genes, and in DNA that is replicated early in the S phase.
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Affiliation(s)
- Mariela C. Torres
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, Hershey, PA17033
| | - Abbey Rebok
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, Hershey, PA17033
| | - Dongxiao Sun
- Department of Pharmacology, Pennsylvania State University, Hershey, PA17033
| | - Thomas E. Spratt
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, Hershey, PA17033
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4
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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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5
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Cornejo-Páramo P, Petrova V, Zhang X, Young RS, Wong ES. Emergence of enhancers at late DNA replicating regions. Nat Commun 2024; 15:3451. [PMID: 38658544 PMCID: PMC11043393 DOI: 10.1038/s41467-024-47391-5] [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: 10/23/2023] [Accepted: 03/26/2024] [Indexed: 04/26/2024] Open
Abstract
Enhancers are fast-evolving genomic sequences that control spatiotemporal gene expression patterns. By examining enhancer turnover across mammalian species and in multiple tissue types, we uncover a relationship between the emergence of enhancers and genome organization as a function of germline DNA replication time. While enhancers are most abundant in euchromatic regions, enhancers emerge almost twice as often in late compared to early germline replicating regions, independent of transposable elements. Using a deep learning sequence model, we demonstrate that new enhancers are enriched for mutations that alter transcription factor (TF) binding. Recently evolved enhancers appear to be mostly neutrally evolving and enriched in eQTLs. They also show more tissue specificity than conserved enhancers, and the TFs that bind to these elements, as inferred by binding sequences, also show increased tissue-specific gene expression. We find a similar relationship with DNA replication time in cancer, suggesting that these observations may be time-invariant principles of genome evolution. Our work underscores that genome organization has a profound impact in shaping mammalian gene regulation.
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Affiliation(s)
- Paola Cornejo-Páramo
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- School of Biotechnology and Biomolecular Sciences, Sydney, NSW, Australia
| | - Veronika Petrova
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- School of Biotechnology and Biomolecular Sciences, Sydney, NSW, Australia
| | - Xuan Zhang
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | - Robert S Young
- Usher Institute, University of Edinburgh, Teviot Place, Edinburgh, EH8 9AG, United Kingdom
- Zhejiang University - University of Edinburgh Institute, Zhejiang University, 718 East Haizhou Road, 314400, Haining, PR China
| | - Emily S Wong
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.
- School of Biotechnology and Biomolecular Sciences, Sydney, NSW, Australia.
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6
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Dreyer J, Ricci G, van den Berg J, Bhardwaj V, Funk J, Armstrong C, van Batenburg V, Sine C, VanInsberghe MA, Marsman R, Mandemaker IK, di Sanzo S, Costantini J, Manzo SG, Biran A, Burny C, Völker-Albert M, Groth A, Spencer SL, van Oudenaarden A, Mattiroli F. Acute multi-level response to defective de novo chromatin assembly in S-phase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.22.586291. [PMID: 38585916 PMCID: PMC10996472 DOI: 10.1101/2024.03.22.586291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Long-term perturbation of de novo chromatin assembly during DNA replication has profound effects on epigenome maintenance and cell fate. The early mechanistic origin of these defects is unknown. Here, we combine acute degradation of Chromatin Assembly Factor 1 (CAF-1), a key player in de novo chromatin assembly, with single-cell genomics, quantitative proteomics, and live-microscopy to uncover these initiating mechanisms in human cells. CAF-1 loss immediately slows down DNA replication speed and renders nascent DNA hyperaccessible. A rapid cellular response, distinct from canonical DNA damage signaling, is triggered and lowers histone mRNAs. As a result, histone variants usage and their modifications are altered, limiting transcriptional fidelity and delaying chromatin maturation within a single S-phase. This multi-level response induces a cell-cycle arrest after mitosis. Our work reveals the immediate consequences of defective de novo chromatin assembly during DNA replication, explaining how at later times the epigenome and cell fate can be altered.
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Affiliation(s)
- Jan Dreyer
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Giulia Ricci
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Jeroen van den Berg
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
- Oncode Institute, The Netherlands
| | - Vivek Bhardwaj
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
- Oncode Institute, The Netherlands
| | - Janina Funk
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Claire Armstrong
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Vincent van Batenburg
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
- Oncode Institute, The Netherlands
| | - Chance Sine
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Michael A. VanInsberghe
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
- Oncode Institute, The Netherlands
| | - Richard Marsman
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Imke K. Mandemaker
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Simone di Sanzo
- MOLEQLAR Analytics GmbH, Rosenheimer Street 141 h, 81671 Munich, Germany
| | - Juliette Costantini
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Stefano G. Manzo
- Oncode Institute, The Netherlands
- Division of Gene Regulation, Netherlands Cancer Institute, The Netherlands
- Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
| | - Alva Biran
- Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen 2200, Denmark
- Biotech Research & Innovation Centre, University of Copenhagen, Copenhagen 2200, Denmark
- Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen 2200, Denmark
| | - Claire Burny
- MOLEQLAR Analytics GmbH, Rosenheimer Street 141 h, 81671 Munich, Germany
| | | | - Anja Groth
- Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen 2200, Denmark
- Biotech Research & Innovation Centre, University of Copenhagen, Copenhagen 2200, Denmark
- Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen 2200, Denmark
| | - Sabrina L. Spencer
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Alexander van Oudenaarden
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
- Oncode Institute, The Netherlands
| | - Francesca Mattiroli
- Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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7
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Lichauco C, Foss EJ, Gatbonton-Schwager T, Athow NF, Lofts BR, Acob R, Taylor E, Lao U, Miles S, Bedalov A. Sir2 and Fun30 regulate ribosomal DNA replication timing via Mcm helicase positioning and nucleosome occupancy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.21.586113. [PMID: 38585982 PMCID: PMC10996493 DOI: 10.1101/2024.03.21.586113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
The association between late replication timing and low transcription rates in eukaryotic heterochromatin is well-known, yet the specific mechanisms underlying this link remain uncertain. In Saccharomyces cerevisiae, the histone deacetylase Sir2 is required for both transcriptional silencing and late replication at the repetitive ribosomal DNA arrays (rDNA). We have previously reported that in the absence of SIR2, a derepressed RNA PolII repositions MCM replicative helicases from their loading site at the ribosomal origin, where they abut well-positioned, high-occupancy nucleosomes, to an adjacent region with lower nucleosome occupancy. By developing a method that can distinguish activation of closely spaced MCM complexes, here we show that the displaced MCMs at rDNA origins have increased firing propensity compared to the non-displaced MCMs. Furthermore, we found that both, activation of the repositioned MCMs and low occupancy of the adjacent nucleosomes critically depend on the chromatin remodeling activity of FUN30. Our study elucidates the mechanism by which Sir2 delays replication timing, and it demonstrates, for the first time, that activation of a specific replication origin in vivo relies on the nucleosome context shaped by a single chromatin remodeler.
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Affiliation(s)
- Carmina Lichauco
- Translational Sciences and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA
| | - Eric J. Foss
- Translational Sciences and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA
| | - Tonibelle Gatbonton-Schwager
- Translational Sciences and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA
| | - Nelson F. Athow
- Translational Sciences and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA
| | - Brandon R. Lofts
- Translational Sciences and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA
| | - Robin Acob
- Translational Sciences and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA
| | - Erin Taylor
- Translational Sciences and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA
| | - Uyen Lao
- Translational Sciences and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA
| | - Shawna Miles
- Translational Sciences and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA
| | - Antonio Bedalov
- Translational Sciences and Therapeutics Division, Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA
- Department of Biochemistry and Department of Medicine, University of Washington, Seattle, WA
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8
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Day M, Tetik B, Parlak M, Almeida-Hernández Y, Räschle M, Kaschani F, Siegert H, Marko A, Sanchez-Garcia E, Kaiser M, Barker IA, Pearl LH, Oliver AW, Boos D. TopBP1 utilises a bipartite GINS binding mode to support genome replication. Nat Commun 2024; 15:1797. [PMID: 38413589 PMCID: PMC10899662 DOI: 10.1038/s41467-024-45946-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 02/07/2024] [Indexed: 02/29/2024] Open
Abstract
Activation of the replicative Mcm2-7 helicase by loading GINS and Cdc45 is crucial for replication origin firing, and as such for faithful genetic inheritance. Our biochemical and structural studies demonstrate that the helicase activator GINS interacts with TopBP1 through two separate binding surfaces, the first involving a stretch of highly conserved amino acids in the TopBP1-GINI region, the second a surface on TopBP1-BRCT4. The two surfaces bind to opposite ends of the A domain of the GINS subunit Psf1. Mutation analysis reveals that either surface is individually able to support TopBP1-GINS interaction, albeit with reduced affinity. Consistently, either surface is sufficient for replication origin firing in Xenopus egg extracts and becomes essential in the absence of the other. The TopBP1-GINS interaction appears sterically incompatible with simultaneous binding of DNA polymerase epsilon (Polε) to GINS when bound to Mcm2-7-Cdc45, although TopBP1-BRCT4 and the Polε subunit PolE2 show only partial competitivity in binding to Psf1. Our TopBP1-GINS model improves the understanding of the recently characterised metazoan pre-loading complex. It further predicts the coordination of three molecular origin firing processes, DNA polymerase epsilon arrival, TopBP1 ejection and GINS integration into Mcm2-7-Cdc45.
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Affiliation(s)
- Matthew Day
- School of Biological and Behavioural Sciences, Blizard Institute, Queen Mary University of London, London, E1 2AT, UK.
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK.
| | - Bilal Tetik
- Molecular Genetics II, Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstraße 2-5, 45141, Essen, Germany
| | - Milena Parlak
- Molecular Genetics II, Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstraße 2-5, 45141, Essen, Germany
| | - Yasser Almeida-Hernández
- Computational Bioengineering, Fakultät Bio- und Chemieingenieurwesen, Technical University Dortmund, Emil-Figge Str. 66, 44227, Dortmund, Germany
- Computational Biochemistry, Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstraße 2-5, 45141, Essen, Germany
| | - Markus Räschle
- Molecular Genetics, Technical University Kaiserslautern, Paul-Ehrlich Straße 24, 67663, Kaiserslautern, Germany
| | - Farnusch Kaschani
- Analytics Core Facility Essen, Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstraße 2-5, 45141, Essen, Germany
- Chemical Biology, Center of Medical Biotechnology, University Duisburg-Essen, Fakultät Biologie, Essen, Germany
| | - Heike Siegert
- Molecular Genetics II, Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstraße 2-5, 45141, Essen, Germany
| | - Anika Marko
- Molecular Genetics II, Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstraße 2-5, 45141, Essen, Germany
| | - Elsa Sanchez-Garcia
- Computational Bioengineering, Fakultät Bio- und Chemieingenieurwesen, Technical University Dortmund, Emil-Figge Str. 66, 44227, Dortmund, Germany
- Computational Biochemistry, Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstraße 2-5, 45141, Essen, Germany
| | - Markus Kaiser
- Analytics Core Facility Essen, Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstraße 2-5, 45141, Essen, Germany
- Chemical Biology, Center of Medical Biotechnology, University Duisburg-Essen, Fakultät Biologie, Essen, Germany
| | - Isabel A Barker
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK
| | - Laurence H Pearl
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK.
- Division of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London, SW1E 6BT, UK.
| | - Antony W Oliver
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK.
| | - Dominik Boos
- Molecular Genetics II, Center of Medical Biotechnology, University of Duisburg-Essen, Universitätsstraße 2-5, 45141, Essen, Germany.
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9
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Foss EJ, Lichauco C, Gatbonton-Schwager T, Gonske SJ, Lofts B, Lao U, Bedalov A. Identification of 1600 replication origins in S. cerevisiae. eLife 2024; 12:RP88087. [PMID: 38315095 PMCID: PMC10945306 DOI: 10.7554/elife.88087] [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] [Indexed: 02/07/2024] Open
Abstract
There are approximately 500 known origins of replication in the yeast genome, and the process by which DNA replication initiates at these locations is well understood. In particular, these sites are made competent to initiate replication by loading of the Mcm replicative helicase prior to the start of S phase; thus, 'a site that binds Mcm in G1' might be considered to provide an operational definition of a replication origin. By fusing a subunit of Mcm to micrococcal nuclease, we previously showed that known origins are typically bound by a single Mcm double hexamer, loaded adjacent to the ARS consensus sequence (ACS). Here, we extend this analysis from known origins to the entire genome, identifying candidate Mcm binding sites whose signal intensity varies over at least three orders of magnitude. Published data quantifying single-stranded DNA (ssDNA) during S phase revealed replication initiation among the most abundant 1600 of these sites, with replication activity decreasing with Mcm abundance and disappearing at the limit of detection of ssDNA. Three other hallmarks of replication origins were apparent among the most abundant 5500 sites. Specifically, these sites: (1) appeared in intergenic nucleosome-free regions flanked on one or both sides by well-positioned nucleosomes; (2) were flanked by ACSs; and (3) exhibited a pattern of GC skew characteristic of replication initiation. We conclude that, if sites at which Mcm double hexamers are loaded can function as replication origins, then DNA replication origins are at least threefold more abundant than previously assumed, and we suggest that replication may occasionally initiate in essentially every intergenic region. These results shed light on recent reports that as many as 15% of replication events initiate outside of known origins, and this broader distribution of replication origins suggest that S phase in yeast may be less distinct from that in humans than widely assumed.
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Affiliation(s)
- Eric J Foss
- Clinical Research Division, Fred Hutch Cancer CenterSeattleUnited States
| | - Carmina Lichauco
- Clinical Research Division, Fred Hutch Cancer CenterSeattleUnited States
| | | | - Sara J Gonske
- Clinical Research Division, Fred Hutch Cancer CenterSeattleUnited States
| | - Brandon Lofts
- Clinical Research Division, Fred Hutch Cancer CenterSeattleUnited States
| | - Uyen Lao
- Clinical Research Division, Fred Hutch Cancer CenterSeattleUnited States
| | - Antonio Bedalov
- Clinical Research Division, Fred Hutch Cancer CenterSeattleUnited States
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10
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Peters L, Venkatachalam A, Ben-Neriah Y. Tissue-Predisposition to Cancer Driver Mutations. Cells 2024; 13:106. [PMID: 38247798 PMCID: PMC10814991 DOI: 10.3390/cells13020106] [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: 12/08/2023] [Revised: 01/02/2024] [Accepted: 01/03/2024] [Indexed: 01/23/2024] Open
Abstract
Driver mutations are considered the cornerstone of cancer initiation. They are defined as mutations that convey a competitive fitness advantage, and hence, their mutation frequency in premalignant tissue is expected to exceed the basal mutation rate. In old terms, that translates to "the survival of the fittest" and implies that a selective process underlies the frequency of cancer driver mutations. In that sense, each tissue is its own niche that creates a molecular selective pressure that may favor the propagation of a mutation or not. At the heart of this stands one of the biggest riddles in cancer biology: the tissue-predisposition to cancer driver mutations. The frequency of cancer driver mutations among tissues is non-uniform: for instance, mutations in APC are particularly frequent in colorectal cancer, and 99% of chronic myeloid leukemia patients harbor the driver BCR-ABL1 fusion mutation, which is rarely found in solid tumors. Here, we provide a mechanistic framework that aims to explain how tissue-specific features, ranging from epigenetic underpinnings to the expression of viral transposable elements, establish a molecular basis for selecting cancer driver mutations in a tissue-specific manner.
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Affiliation(s)
| | | | - Yinon Ben-Neriah
- Lautenberg Center for Immunology and Cancer Research, Institute for Medical Research (IMRIC), The Faculty of Medicine, Hebrew University of Jerusalem, P.O. Box 12272, Jerusalem 91120, Israel; (L.P.); (A.V.)
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11
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Singh A, Chakrabarti S. Diffusion controls local versus dispersed inheritance of histones during replication and shapes epigenomic architecture. PLoS Comput Biol 2023; 19:e1011725. [PMID: 38109423 PMCID: PMC10760866 DOI: 10.1371/journal.pcbi.1011725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 01/02/2024] [Accepted: 12/01/2023] [Indexed: 12/20/2023] Open
Abstract
The dynamics of inheritance of histones and their associated modifications across cell divisions can have major consequences on maintenance of the cellular epigenomic state. Recent experiments contradict the long-held notion that histone inheritance during replication is always local, suggesting that active and repressed regions of the genome exhibit fundamentally different histone dynamics independent of transcription-coupled turnover. Here we develop a stochastic model of histone dynamics at the replication fork and demonstrate that differential diffusivity of histones in active versus repressed chromatin is sufficient to quantitatively explain these recent experiments. Further, we use the model to predict patterns in histone mark similarity between pairs of genomic loci that should be developed as a result of diffusion, but cannot originate from either PRC2 mediated mark spreading or transcriptional processes. Interestingly, using a combination of CHIP-seq, replication timing and Hi-C datasets we demonstrate that all the computationally predicted patterns are consistently observed for both active and repressive histone marks in two different cell lines. While direct evidence for histone diffusion remains controversial, our results suggest that dislodged histones in euchromatin and facultative heterochromatin may exhibit some level of diffusion within "Diffusion-Accessible-Domains" (DADs), leading to redistribution of epigenetic marks within and across chromosomes. Preservation of the epigenomic state across cell divisions therefore might be achieved not by passing on strict positional information of histone marks, but by maintaining the marks in somewhat larger DADs of the genome.
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Affiliation(s)
- Archit Singh
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Shaon Chakrabarti
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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12
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Lee CSK, Weiβ M, Hamperl S. Where and when to start: Regulating DNA replication origin activity in eukaryotic genomes. Nucleus 2023; 14:2229642. [PMID: 37469113 PMCID: PMC10361152 DOI: 10.1080/19491034.2023.2229642] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/21/2023] Open
Abstract
In eukaryotic genomes, hundreds to thousands of potential start sites of DNA replication named origins are dispersed across each of the linear chromosomes. During S-phase, only a subset of origins is selected in a stochastic manner to assemble bidirectional replication forks and initiate DNA synthesis. Despite substantial progress in our understanding of this complex process, a comprehensive 'identity code' that defines origins based on specific nucleotide sequences, DNA structural features, the local chromatin environment, or 3D genome architecture is still missing. In this article, we review the genetic and epigenetic features of replication origins in yeast and metazoan chromosomes and highlight recent insights into how this flexibility in origin usage contributes to nuclear organization, cell growth, differentiation, and genome stability.
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Affiliation(s)
- Clare S K Lee
- Chromosome Dynamics and Genome Stability, Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Matthias Weiβ
- Chromosome Dynamics and Genome Stability, Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Stephan Hamperl
- Chromosome Dynamics and Genome Stability, Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
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13
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Foss EJ, Lichauco C, Gatbonton-Schwager T, Gonske SJ, Lofts B, Lao U, Bedalov A. Identification of 1600 replication origins in S. cerevisiae. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.11.536402. [PMID: 38014147 PMCID: PMC10680564 DOI: 10.1101/2023.04.11.536402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
There are approximately 500 known origins of replication in the yeast genome, and the process by which DNA replication initiates at these locations is well understood. In particular, these sites are made competent to initiate replication by loading of the Mcm replicative helicase prior to the start of S phase; thus, "a site to which MCM is bound in G1" might be considered to provide an operational definition of a replication origin. By fusing a subunit of Mcm to micrococcal nuclease, a technique referred to as "Chromatin Endogenous Cleavage", we previously showed that known origins are typically bound by a single Mcm double hexamer, loaded adjacent to the ARS consensus sequence (ACS). Here we extend this analysis from known origins to the entire genome, identifying candidate Mcm binding sites whose signal intensity varies over at least 3 orders of magnitude. Published data quantifying the production of ssDNA during S phase showed clear evidence of replication initiation among the most abundant 1600 of these sites, with replication activity decreasing in concert with Mcm abundance and disappearing at the limit of detection of ssDNA. Three other hallmarks of replication origins were apparent among the most abundant 5,500 sites. Specifically, these sites (1) appeared in intergenic nucleosome-free regions that were flanked on one or both sides by well-positioned nucleosomes; (2) were flanked by ACSs; and (3) exhibited a pattern of GC skew characteristic of replication initiation. Furthermore, the high resolution of this technique allowed us to demonstrate a strong bias for detecting Mcm double-hexamers downstream rather than upstream of the ACS, which is consistent with the directionality of Mcm loading by Orc that has been observed in vitro. We conclude that, if sites at which Mcm double-hexamers are loaded can function as replication origins, then DNA replication origins are at least 3-fold more abundant than previously assumed, and we suggest that replication may occasionally initiate in essentially every intergenic region. These results shed light on recent reports that as many as 15% of replication events initiate outside of known origins, and this broader distribution of replication origins suggest that S phase in yeast may be less distinct from that in humans than is widely assumed.
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Affiliation(s)
- Eric J Foss
- Clinical Research Division, Fred Hutch Cancer Center, Seattle, WA 98109
| | - Carmina Lichauco
- Clinical Research Division, Fred Hutch Cancer Center, Seattle, WA 98109
| | | | - Sara J Gonske
- Clinical Research Division, Fred Hutch Cancer Center, Seattle, WA 98109
| | - Brandon Lofts
- Clinical Research Division, Fred Hutch Cancer Center, Seattle, WA 98109
| | - Uyen Lao
- Clinical Research Division, Fred Hutch Cancer Center, Seattle, WA 98109
| | - Antonio Bedalov
- Clinical Research Division, Fred Hutch Cancer Center, Seattle, WA 98109
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14
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Walczyk AM, Hersch-Green EI. Genome-material costs and functional trade-offs in the autopolyploid Solidago gigantea (giant goldenrod) series. AMERICAN JOURNAL OF BOTANY 2023; 110:e16218. [PMID: 37551707 DOI: 10.1002/ajb2.16218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 06/21/2023] [Accepted: 06/21/2023] [Indexed: 08/09/2023]
Abstract
PREMISE Increased genome-material costs of N and P atoms inherent to organisms with larger genomes have been proposed to limit growth under nutrient scarcities and to promote growth under nutrient enrichments. Such responsiveness may reflect a nutrient-dependent diploid versus polyploid advantage that could have vast ecological and evolutionary implications, but direct evidence that material costs increase with ploidy level and/or influence cytotype-dependent growth, metabolic, and/or resource-use trade-offs is limited. METHODS We grew diploid, autotetraploid, and autohexaploid Solidago gigantea plants with one of four ambient or enriched N:P ratios and measured traits related to material costs, primary and secondary metabolism, and resource-use. RESULTS Relative to diploids, polyploids invested more N and P into cells, and tetraploids grew more with N enrichments, suggesting that material costs increase with ploidy level. Polyploids also generally exhibited strategies that could minimize material-cost constraints over both long (reduced monoploid genome size) and short (more extreme transcriptome downsizing, reduced photosynthesis rates and terpene concentrations, enhanced N-use efficiencies) evolutionary time periods. Furthermore, polyploids had lower transpiration rates but higher water-use efficiencies than diploids, both of which were more pronounced under nutrient-limiting conditions. CONCLUSIONS N and P material costs increase with ploidy level, but material-cost constraints might be lessened by resource allocation/investment mechanisms that can also alter ecological dynamics and selection. Our results enhance mechanistic understanding of how global increases in nutrients might provide a release from material-cost constraints in polyploids that could impact ploidy (or genome-size)-specific performances, cytogeographic patterning, and multispecies community structuring.
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Affiliation(s)
- Angela M Walczyk
- Department of Biological Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI, 49931, USA
- Biology Department, Gustavus Adolphus College, 800 West College Avenue, St. Peter, MN, 56082, USA
| | - Erika I Hersch-Green
- Department of Biological Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI, 49931, USA
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15
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Hernández‐Carralero E, Cabrera E, Rodríguez-Torres G, Hernández-Reyes Y, Singh A, Santa-María C, Fernández-Justel J, Janssens R, Marteijn J, Evert B, Mailand N, Gómez M, Ramadan K, Smits VJ, Freire R. ATXN3 controls DNA replication and transcription by regulating chromatin structure. Nucleic Acids Res 2023; 51:5396-5413. [PMID: 36971114 PMCID: PMC10287915 DOI: 10.1093/nar/gkad212] [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: 07/12/2022] [Revised: 02/10/2023] [Accepted: 03/14/2023] [Indexed: 11/18/2023] Open
Abstract
The deubiquitinating enzyme Ataxin-3 (ATXN3) contains a polyglutamine (PolyQ) region, the expansion of which causes spinocerebellar ataxia type-3 (SCA3). ATXN3 has multiple functions, such as regulating transcription or controlling genomic stability after DNA damage. Here we report the role of ATXN3 in chromatin organization during unperturbed conditions, in a catalytic-independent manner. The lack of ATXN3 leads to abnormalities in nuclear and nucleolar morphology, alters DNA replication timing and increases transcription. Additionally, indicators of more open chromatin, such as increased mobility of histone H1, changes in epigenetic marks and higher sensitivity to micrococcal nuclease digestion were detected in the absence of ATXN3. Interestingly, the effects observed in cells lacking ATXN3 are epistatic to the inhibition or lack of the histone deacetylase 3 (HDAC3), an interaction partner of ATXN3. The absence of ATXN3 decreases the recruitment of endogenous HDAC3 to the chromatin, as well as the HDAC3 nuclear/cytoplasm ratio after HDAC3 overexpression, suggesting that ATXN3 controls the subcellular localization of HDAC3. Importantly, the overexpression of a PolyQ-expanded version of ATXN3 behaves as a null mutant, altering DNA replication parameters, epigenetic marks and the subcellular distribution of HDAC3, giving new insights into the molecular basis of the disease.
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Affiliation(s)
- Esperanza Hernández‐Carralero
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Escuela de Doctorado y Estudios de Posgrado, Universidad de la Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Elisa Cabrera
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
| | - Gara Rodríguez-Torres
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Escuela de Doctorado y Estudios de Posgrado, Universidad de la Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Yeray Hernández-Reyes
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Escuela de Doctorado y Estudios de Posgrado, Universidad de la Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Abhay N Singh
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
| | - Cristina Santa-María
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Madrid, Spain
| | - José Miguel Fernández-Justel
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Madrid, Spain
| | - Roel C Janssens
- Department of Molecular Genetics, Oncode Institute, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Jurgen A Marteijn
- Department of Molecular Genetics, Oncode Institute, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Bernd O Evert
- Department of Neurology, University Hospital Bonn, Bonn, Germany
| | - Niels Mailand
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
- Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - María Gómez
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Madrid, Spain
| | - Kristijan Ramadan
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
| | - Veronique A J Smits
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
- Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
| | - Raimundo Freire
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
- Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
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16
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Caballero M, Boos D, Koren A. Cell-type specificity of the human mutation landscape with respect to DNA replication dynamics. CELL GENOMICS 2023; 3:100315. [PMID: 37388911 PMCID: PMC10300547 DOI: 10.1016/j.xgen.2023.100315] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/24/2023] [Accepted: 04/03/2023] [Indexed: 07/01/2023]
Abstract
The patterns of genomic mutations are associated with various genomic features, most notably late replication timing, yet it remains contested which mutation types and signatures relate to DNA replication dynamics and to what extent. Here, we perform high-resolution comparisons of mutational landscapes between lymphoblastoid cell lines, chronic lymphocytic leukemia tumors, and three colon adenocarcinoma cell lines, including two with mismatch repair deficiency. Using cell-type-matched replication timing profiles, we demonstrate that mutation rates exhibit heterogeneous replication timing associations among cell types. This cell-type heterogeneity extends to the underlying mutational pathways, as mutational signatures show inconsistent replication timing bias between cell types. Moreover, replicative strand asymmetries exhibit similar cell-type specificity, albeit with different relationships to replication timing than mutation rates. Overall, we reveal an underappreciated complexity and cell-type specificity of mutational pathways and their relationship to replication timing.
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Affiliation(s)
- Madison Caballero
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Dominik Boos
- Vertebrate DNA Replication Lab, Center of Medical Biotechnology, University of Duisburg-Essen, 45117 Essen, Germany
| | - Amnon Koren
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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17
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Oses C, Francia MG, Verneri P, Vazquez Echegaray C, Guberman AS, Levi V. The dynamical organization of the core pluripotency transcription factors responds to differentiation cues in early S-phase. Front Cell Dev Biol 2023; 11:1125015. [PMID: 37215075 PMCID: PMC10192714 DOI: 10.3389/fcell.2023.1125015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/21/2023] [Indexed: 05/24/2023] Open
Abstract
DNA replication in stem cells is a major challenge for pluripotency preservation and cell fate decisions. This process involves massive changes in the chromatin architecture and the reorganization of many transcription-related molecules in different spatial and temporal scales. Pluripotency is controlled by the master transcription factors (TFs) OCT4, SOX2 and NANOG that partition into condensates in the nucleus of embryonic stem cells. These condensates are proposed to play relevant roles in the regulation of gene expression and the maintenance of pluripotency. Here, we asked whether the dynamical distribution of the pluripotency TFs changes during the cell cycle, particularly during DNA replication. Since the S phase is considered to be a window of opportunity for cell fate decisions, we explored if differentiation cues in G1 phase trigger changes in the distribution of these TFs during the subsequent S phase. Our results show a spatial redistribution of TFs condensates during DNA replication which was not directly related to chromatin compaction. Additionally, fluorescence fluctuation spectroscopy revealed TF-specific, subtle changes in the landscape of TF-chromatin interactions, consistent with their particularities as key players of the pluripotency network. Moreover, we found that differentiation stimuli in the preceding G1 phase triggered a relatively fast and massive reorganization of pluripotency TFs in early-S phase. Particularly, OCT4 and SOX2 condensates dissolved whereas the lifetimes of TF-chromatin interactions increased suggesting that the reorganization of condensates is accompanied with a change in the landscape of TF-chromatin interactions. Notably, NANOG showed impaired interactions with chromatin in stimulated early-S cells in line with its role as naïve pluripotency TF. Together, these findings provide new insights into the regulation of the core pluripotency TFs during DNA replication of embryonic stem cells and highlight their different roles at early differentiation stages.
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Affiliation(s)
- Camila Oses
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marcos Gabriel Francia
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Paula Verneri
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Camila Vazquez Echegaray
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Alejandra Sonia Guberman
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Valeria Levi
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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18
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Dimond A, Van de Pette M, Taylor-Bateman V, Brown K, Sardini A, Whilding C, Feytout A, Prinjha RK, Merkenschlager M, Fisher AG. Drug-induced loss of imprinting revealed using bioluminescent reporters of Cdkn1c. Sci Rep 2023; 13:5626. [PMID: 37024615 PMCID: PMC10079848 DOI: 10.1038/s41598-023-32747-6] [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: 12/15/2022] [Accepted: 03/31/2023] [Indexed: 04/08/2023] Open
Abstract
Genomic imprinting is an epigenetically mediated mechanism that regulates allelic expression of genes based upon parent-of-origin and provides a paradigm for studying epigenetic silencing and release. Here, bioluminescent reporters for the maternally-expressed imprinted gene Cdkn1c are used to examine the capacity of chromatin-modifying drugs to reverse paternal Cdkn1c silencing. Exposure of reporter mouse embryonic stem cells (mESCs) to 5-Azacytidine, HDAC inhibitors, BET inhibitors or GSK-J4 (KDM6A/B inhibitor) relieved repression of paternal Cdkn1c, either selectively or by inducing biallelic effects. Treatment of reporter fibroblasts with HDAC inhibitors or GSK-J4 resulted in similar paternal Cdkn1c activation, whereas BET inhibitor-induced loss of imprinting was specific to mESCs. Changes in allelic expression were generally not sustained in dividing cultures upon drug removal, indicating that the underlying epigenetic memory of silencing was maintained. In contrast, Cdkn1c de-repression by GSK-J4 was retained in both mESCs and fibroblasts following inhibitor removal, although this impact may be linked to cellular stress and DNA damage. Taken together, these data introduce bioluminescent reporter cells as tools for studying epigenetic silencing and disruption, and demonstrate that Cdkn1c imprinting requires distinct and cell-type specific chromatin features and modifying enzymes to enact and propagate a memory of silencing.
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Affiliation(s)
- Andrew Dimond
- Epigenetic Memory Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.
| | - Mathew Van de Pette
- Epigenetic Memory Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
- MRC Toxicology Unit, University of Cambridge, Gleeson Building, Tennis Court Road, Cambridge, CB2 1QR, UK
| | - Victoria Taylor-Bateman
- Epigenetic Memory Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Karen Brown
- Epigenetic Memory Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Alessandro Sardini
- Whole Animal Physiology and Imaging, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Chad Whilding
- Microscopy Facility, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Amelie Feytout
- Epigenetic Memory Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Rab K Prinjha
- Immunology and Epigenetics Research Unit, Research, GlaxoSmithKline, Gunnels Wood Road, Stevenage, SG1 2NY, Herts, UK
| | - Matthias Merkenschlager
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Amanda G Fisher
- Epigenetic Memory Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.
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19
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Bracci AN, Dallmann A, Ding Q, Hubisz MJ, Caballero M, Koren A. The evolution of the human DNA replication timing program. Proc Natl Acad Sci U S A 2023; 120:e2213896120. [PMID: 36848554 PMCID: PMC10013799 DOI: 10.1073/pnas.2213896120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 01/23/2023] [Indexed: 03/01/2023] Open
Abstract
DNA is replicated according to a defined spatiotemporal program that is linked to both gene regulation and genome stability. The evolutionary forces that have shaped replication timing programs in eukaryotic species are largely unknown. Here, we studied the molecular causes and consequences of replication timing evolution across 94 humans, 95 chimpanzees, and 23 rhesus macaques. Replication timing differences recapitulated the species' phylogenetic tree, suggesting continuous evolution of the DNA replication timing program in primates. Hundreds of genomic regions had significant replication timing variation between humans and chimpanzees, of which 66 showed advances in replication origin firing in humans, while 57 were delayed. Genes overlapping these regions displayed correlated changes in expression levels and chromatin structure. Many human-chimpanzee variants also exhibited interindividual replication timing variation, pointing to ongoing evolution of replication timing at these loci. Association of replication timing variation with genetic variation revealed that DNA sequence evolution can explain replication timing variation between species. Taken together, DNA replication timing shows substantial and ongoing evolution in the human lineage that is driven by sequence alterations and could impact regulatory evolution at specific genomic sites.
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Affiliation(s)
- Alexa N. Bracci
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Anissa Dallmann
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Qiliang Ding
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Melissa J. Hubisz
- Bioinformatics Facility, Institute of Biotechnology, Cornell University, Ithaca, NY14853
| | - Madison Caballero
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Amnon Koren
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
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20
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Mutation Rate and Spectrum of the Silkworm in Normal and Temperature Stress Conditions. Genes (Basel) 2023; 14:genes14030649. [PMID: 36980921 PMCID: PMC10048334 DOI: 10.3390/genes14030649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 02/26/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Mutation rate is a crucial parameter in evolutionary genetics. However, the mutation rate of most species as well as the extent to which the environment can alter the genome of multicellular organisms remain poorly understood. Here, we used parents–progeny sequencing to investigate the mutation rate and spectrum of the domestic silkworm (Bombyx mori) among normal and two temperature stress conditions (32 °C and 0 °C). The rate of single-nucleotide mutations in the normal temperature rearing condition was 0.41 × 10−8 (95% confidence interval, 0.33 × 10−8–0.49 × 10−8) per site per generation, which was up to 1.5-fold higher than in four previously studied insects. Moreover, the mutation rates of the silkworm under the stresses are significantly higher than in normal conditions. Furthermore, the mutation rate varies less in gene regions under normal and temperature stresses. Together, these findings expand the known diversity of the mutation rate among eukaryotes but also have implications for evolutionary analysis that assumes a constant mutation rate among species and environments.
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21
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Moeckel C, Zaravinos A, Georgakopoulos-Soares I. Strand Asymmetries Across Genomic Processes. Comput Struct Biotechnol J 2023; 21:2036-2047. [PMID: 36968020 PMCID: PMC10030826 DOI: 10.1016/j.csbj.2023.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/08/2023] [Accepted: 03/08/2023] [Indexed: 03/12/2023] Open
Abstract
Across biological systems, a number of genomic processes, including transcription, replication, DNA repair, and transcription factor binding, display intrinsic directionalities. These directionalities are reflected in the asymmetric distribution of nucleotides, motifs, genes, transposon integration sites, and other functional elements across the two complementary strands. Strand asymmetries, including GC skews and mutational biases, have shaped the nucleotide composition of diverse organisms. The investigation of strand asymmetries often serves as a method to understand underlying biological mechanisms, including protein binding preferences, transcription factor interactions, retrotransposition, DNA damage and repair preferences, transcription-replication collisions, and mutagenesis mechanisms. Research into this subject also enables the identification of functional genomic sites, such as replication origins and transcription start sites. Improvements in our ability to detect and quantify DNA strand asymmetries will provide insights into diverse functionalities of the genome, the contribution of different mutational mechanisms in germline and somatic mutagenesis, and our knowledge of genome instability and evolution, which all have significant clinical implications in human disease, including cancer. In this review, we describe key developments that have been made across the field of genomic strand asymmetries, as well as the discovery of associated mechanisms.
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Affiliation(s)
- Camille Moeckel
- Institute for Personalized Medicine, Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Apostolos Zaravinos
- Department of Life Sciences, European University Cyprus, Diogenis Str., 6, Nicosia 2404, Cyprus
- Cancer Genetics, Genomics and Systems Biology laboratory, Basic and Translational Cancer Research Center (BTCRC), Nicosia 1516, Cyprus
- Corresponding author at: Department of Life Sciences, European University Cyprus, Diogenis Str., 6, Nicosia 2404, Cyprus.
| | - Ilias Georgakopoulos-Soares
- Institute for Personalized Medicine, Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
- Corresponding author.
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22
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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: 32] [Impact Index Per Article: 32.0] [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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23
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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: 18] [Impact Index Per Article: 18.0] [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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24
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Zagelbaum J, Gautier J. Double-strand break repair and mis-repair in 3D. DNA Repair (Amst) 2023; 121:103430. [PMID: 36436496 PMCID: PMC10799305 DOI: 10.1016/j.dnarep.2022.103430] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/13/2022] [Accepted: 11/15/2022] [Indexed: 11/18/2022]
Abstract
DNA double-strand breaks (DSBs) are lesions that arise frequently from exposure to damaging agents as well as from ongoing physiological DNA transactions. Mis-repair of DSBs leads to rearrangements and structural variations in chromosomes, including insertions, deletions, and translocations implicated in disease. The DNA damage response (DDR) limits pathologic mutations and large-scale chromosome rearrangements. DSB repair initiates in 2D at DNA lesions with the stepwise recruitment of repair proteins and local chromatin remodeling which facilitates break accessibility. More complex structures are then formed via protein assembly into nanodomains and via genome folding into chromatin loops. Subsequently, 3D reorganization of DSBs is guided by clustering forces which drive the assembly of repair domains harboring multiple lesions. These domains are further stabilized and insulated into condensates via liquid-liquid phase-separation. Here, we discuss the benefits and risks associated with this 3D reorganization of the broken genome.
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Affiliation(s)
- Jennifer Zagelbaum
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA; Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Jean Gautier
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA; Department of Genetics and Development, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
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25
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Shokraneh N, Arab M, Libbrecht M. Integrative chromatin domain annotation through graph embedding of Hi-C data. Bioinformatics 2022; 39:6935783. [PMID: 36534827 PMCID: PMC9848054 DOI: 10.1093/bioinformatics/btac813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 11/02/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
MOTIVATION The organization of the genome into domains plays a central role in gene expression and other cellular activities. Researchers identify genomic domains mainly through two views: 1D functional assays such as ChIP-seq, and chromatin conformation assays such as Hi-C. Fully understanding domains requires integrative modeling that combines these two views. However, the predominant form of integrative modeling uses segmentation and genome annotation (SAGA) along with the rigid assumption that loci in contact are more likely to share the same domain type, which is not necessarily true for epigenomic domain types and genome-wide chromatin interactions. RESULTS Here, we present an integrative approach that annotates domains using both 1D functional genomic signals and Hi-C measurements of genome-wide 3D interactions without the use of a pairwise prior. We do so by using a graph embedding to learn structural features corresponding to each genomic region, then inputting learned structural features along with functional genomic signals to a SAGA algorithm. We show that our domain types recapitulate well-known subcompartments with an additional granularity that distinguishes a combination of the spatial and functional states of the genomic regions. In particular, we identified a division of the previously identified A2 subcompartment such that the divided domain types have significantly varying expression levels. AVAILABILITY AND IMPLEMENTATION https://github.com/nedashokraneh/IChDA. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Neda Shokraneh
- Computing Science Department, Simon Fraser University, Burnaby V5A 1S6, Canada
| | - Mariam Arab
- Computing Science Department, Simon Fraser University, Burnaby V5A 1S6, Canada
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26
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Andreyeva EN, Emelyanov AV, Nevil M, Sun L, Vershilova E, Hill CA, Keogh MC, Duronio RJ, Skoultchi AI, Fyodorov DV. Drosophila SUMM4 complex couples insulator function and DNA replication control. eLife 2022; 11:e81828. [PMID: 36458689 PMCID: PMC9917439 DOI: 10.7554/elife.81828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 11/28/2022] [Indexed: 12/05/2022] Open
Abstract
Asynchronous replication of chromosome domains during S phase is essential for eukaryotic genome function, but the mechanisms establishing which domains replicate early versus late in different cell types remain incompletely understood. Intercalary heterochromatin domains replicate very late in both diploid chromosomes of dividing cells and in endoreplicating polytene chromosomes where they are also underreplicated. Drosophila SNF2-related factor SUUR imparts locus-specific underreplication of polytene chromosomes. SUUR negatively regulates DNA replication fork progression; however, its mechanism of action remains obscure. Here, we developed a novel method termed MS-Enabled Rapid protein Complex Identification (MERCI) to isolate a stable stoichiometric native complex SUMM4 that comprises SUUR and a chromatin boundary protein Mod(Mdg4)-67.2. Mod(Mdg4) stimulates SUUR ATPase activity and is required for a normal spatiotemporal distribution of SUUR in vivo. SUUR and Mod(Mdg4)-67.2 together mediate the activities of gypsy insulator that prevent certain enhancer-promoter interactions and establish euchromatin-heterochromatin barriers in the genome. Furthermore, SuUR or mod(mdg4) mutations reverse underreplication of intercalary heterochromatin. Thus, SUMM4 can impart late replication of intercalary heterochromatin by attenuating the progression of replication forks through euchromatin/heterochromatin boundaries. Our findings implicate a SNF2 family ATP-dependent motor protein SUUR in the insulator function, reveal that DNA replication can be delayed by a chromatin barrier, and uncover a critical role for architectural proteins in replication control. They suggest a mechanism for the establishment of late replication that does not depend on an asynchronous firing of late replication origins.
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Affiliation(s)
- Evgeniya N Andreyeva
- Department of Cell Biology, Albert Einstein College of MedicineBronxUnited States
| | | | - Markus Nevil
- UNC-SPIRE, University of North CarolinaChapel HillUnited States
| | - Lu Sun
- EpiCypherDurhamUnited States
| | - Elena Vershilova
- Department of Cell Biology, Albert Einstein College of MedicineBronxUnited States
| | - Christina A Hill
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel HillChapel HillUnited States
| | | | - Robert J Duronio
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel HillChapel HillUnited States
- Lineberger Comprehensive Cancer Center, University of North CarolinaChapel HillUnited States
- Department of Biology, University of North CarolinaChapel HillUnited States
- Department of Genetics, University of North CarolinaChapel HillUnited States
| | - Arthur I Skoultchi
- Department of Cell Biology, Albert Einstein College of MedicineBronxUnited States
| | - Dmitry V Fyodorov
- Department of Cell Biology, Albert Einstein College of MedicineBronxUnited States
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27
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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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28
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Dao FY, Lv H, Fullwood MJ, Lin H. Accurate Identification of DNA Replication Origin by Fusing Epigenomics and Chromatin Interaction Information. RESEARCH (WASHINGTON, D.C.) 2022; 2022:9780293. [PMID: 36405252 PMCID: PMC9667886 DOI: 10.34133/2022/9780293] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 09/30/2022] [Indexed: 07/29/2023]
Abstract
DNA replication initiation is a complex process involving various genetic and epigenomic signatures. The correct identification of replication origins (ORIs) could provide important clues for the study of a variety of diseases caused by replication. Here, we design a computational approach named iORI-Epi to recognize ORIs by incorporating epigenome-based features, sequence-based features, and 3D genome-based features. The iORI-Epi displays excellent robustness and generalization ability on both training datasets and independent datasets of K562 cell line. Further experiments confirm that iORI-Epi is highly scalable in other cell lines (MCF7 and HCT116). We also analyze and clarify the regulatory role of epigenomic marks, DNA motifs, and chromatin interaction in DNA replication initiation of eukaryotic genomes. Finally, we discuss gene enrichment pathways from the perspective of ORIs in different replication timing states and heuristically dissect the effect of promoters on replication initiation. Our computational methodology is worth extending to ORI identification in other eukaryotic species.
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Affiliation(s)
- Fu-Ying Dao
- Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 610054, China
- School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Dr, Singapore 117599, Singapore
| | - Hao Lv
- Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 610054, China
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Melissa J. Fullwood
- School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Dr, Singapore 117599, Singapore
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A∗STAR), Singapore 138673, Singapore
| | - Hao Lin
- Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 610054, China
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29
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Exploration of Tools for the Interpretation of Human Non-Coding Variants. Int J Mol Sci 2022; 23:ijms232112977. [PMID: 36361767 PMCID: PMC9654743 DOI: 10.3390/ijms232112977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/17/2022] [Accepted: 10/23/2022] [Indexed: 02/01/2023] Open
Abstract
The advent of Whole Genome Sequencing (WGS) broadened the genetic variation detection range, revealing the presence of variants even in non-coding regions of the genome, which would have been missed using targeted approaches. One of the most challenging issues in WGS analysis regards the interpretation of annotated variants. This review focuses on tools suitable for the functional annotation of variants falling into non-coding regions. It couples the description of non-coding genomic areas with the results and performance of existing tools for a functional interpretation of the effect of variants in these regions. Tools were tested in a controlled genomic scenario, representing the ground-truth and allowing us to determine software performance.
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30
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Santos MM, Johnson MC, Fiedler L, Zegerman P. Global early replication disrupts gene expression and chromatin conformation in a single cell cycle. Genome Biol 2022; 23:217. [PMID: 36253803 PMCID: PMC9575230 DOI: 10.1186/s13059-022-02788-7] [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: 05/06/2022] [Accepted: 10/10/2022] [Indexed: 12/03/2022] Open
Abstract
Background The early embryonic divisions of many organisms, including fish, flies, and frogs, are characterized by a very rapid S-phase caused by high rates of replication initiation. In somatic cells, S-phase is much longer due to both a reduction in the total number of initiation events and the imposition of a temporal order of origin activation. The physiological importance of changes in the rate and timing of replication initiation in S-phase remains unclear. Results Here we assess the importance of the temporal control of replication initiation using a conditional system in budding yeast to drive the early replication of the majority of origins in a single cell cycle. We show that global early replication disrupts the expression of over a quarter of all genes. By deleting individual origins, we show that delaying replication is sufficient to restore normal gene expression, directly implicating origin firing control in this regulation. Global early replication disrupts nucleosome positioning and transcription factor binding during S-phase, suggesting that the rate of S-phase is important to regulate the chromatin landscape. Conclusions Together, these data provide new insight into the role of the temporal control of origin firing during S-phase for coordinating replication, gene expression, and chromatin establishment as occurs in the early embryo. Supplementary Information The online version contains supplementary material available at 10.1186/s13059-022-02788-7.
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Affiliation(s)
- Miguel M Santos
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK.,Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Mark C Johnson
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK.,Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Lukáš Fiedler
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK.,Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Philip Zegerman
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK. .,Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK.
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31
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Rpd3 regulates single-copy origins independently of the rDNA array by opposing Fkh1-mediated origin stimulation. Proc Natl Acad Sci U S A 2022; 119:e2212134119. [PMID: 36161938 PMCID: PMC9546531 DOI: 10.1073/pnas.2212134119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
The faithful replication of eukaryotic genomes requires balancing the replication capacities of different genomic regions, such as repetitive versus single-copy genetic elements, which may compete for limiting replication resources, possibly leading to replication stress and genome instability. We examined the function of histone deacetylases Rpd3 and Sir2 in balancing replication between unique genome sequences and the multicopy ribosomal DNA genes. Our findings support prior conclusions that Sir2 directly suppresses early firing of rDNA origins, thereby enabling balanced replication of the genome. We further show that Rpd3’s function in delaying firing of later-firing, single-copy origins is independent of Sir2 and rDNA load. Instead, Rpd3 appears to oppose the Fkh1/2 origin activation pathway by regulating binding of the origin-stimulator Fkh1. Eukaryotic chromosomes are organized into structural and functional domains with characteristic replication timings, which are thought to contribute to epigenetic programming and genome stability. Differential replication timing results from epigenetic mechanisms that positively and negatively regulate the competition for limiting replication initiation factors. Histone deacetylase Sir2 negatively regulates initiation of the multicopy (∼150) rDNA origins, while Rpd3 histone deacetylase negatively regulates firing of single-copy origins. However, Rpd3’s effect on single-copy origins might derive indirectly from a positive function for Rpd3 in rDNA origin firing shifting the competitive balance. Our quantitative experiments support the idea that origins compete for limiting factors; however, our results show that Rpd3’s effect on single-copy origin is independent of rDNA copy-number and of Sir2’s effects on rDNA origin firing. Whereas RPD3 deletion and SIR2 deletion alter the early S phase dynamics of single-copy and rDNA origin firings in opposite fashion, unexpectedly only RPD3 deletion suppresses overall rDNA origin efficiency across S phase. Increased origin activation in rpd3Δ requires Fkh1/2, suggesting that Rpd3 opposes Fkh1/2-origin stimulation, which involves recruitment of Dbf4-dependent kinase (DDK). Indeed, Fkh1 binding increases at Rpd3-regulated origins in rpd3Δ cells in G1, supporting a mechanism whereby Rpd3 influences initiation timing of single-copy origins directly through modulation of Fkh1-origin binding. Genetic suppression of a DBF4 hypomorphic mutation by RPD3 deletion further supports the conclusion that Rpd3 impedes DDK recruitment by Fkh1, revealing a mechanism of Rpd3 in origin regulation.
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32
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Nucleosome-directed replication origin licensing independent of a consensus DNA sequence. Nat Commun 2022; 13:4947. [PMID: 35999198 PMCID: PMC9399094 DOI: 10.1038/s41467-022-32657-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 08/09/2022] [Indexed: 02/08/2023] Open
Abstract
The numerous enzymes and cofactors involved in eukaryotic DNA replication are conserved from yeast to human, and the budding yeast Saccharomyces cerevisiae (S.c.) has been a useful model organism for these studies. However, there is a gap in our knowledge of why replication origins in higher eukaryotes do not use a consensus DNA sequence as found in S.c. Using in vitro reconstitution and single-molecule visualization, we show here that S.c. origin recognition complex (ORC) stably binds nucleosomes and that ORC-nucleosome complexes have the intrinsic ability to load the replicative helicase MCM double hexamers onto adjacent nucleosome-free DNA regardless of sequence. Furthermore, we find that Xenopus laevis nucleosomes can substitute for yeast ones in engaging with ORC. Combined with re-analyses of genome-wide ORC binding data, our results lead us to propose that the yeast origin recognition machinery contains the cryptic capacity to bind nucleosomes near a nucleosome-free region and license origins, and that this nucleosome-directed origin licensing paradigm generalizes to all eukaryotes. Most eukaryotes do not use a consensus DNA sequence as binding sites for the origin recognition complex (ORC) to initiate DNA replication, however budding yeast do. Here the authors show S. cerevisiae ORC can bind nucleosomes near nucleosome-free regions and recruit replicative helicases to form a pre-replication complex independent of the DNA sequence.
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33
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JENKINSON F, ZEGERMAN P. Roles of phosphatases in eukaryotic DNA replication initiation control. DNA Repair (Amst) 2022; 118:103384. [DOI: 10.1016/j.dnarep.2022.103384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/28/2022] [Accepted: 07/30/2022] [Indexed: 11/03/2022]
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34
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Clarke TL, Mostoslavsky R. DNA repair as a shared hallmark in cancer and ageing. Mol Oncol 2022; 16:3352-3379. [PMID: 35834102 PMCID: PMC9490147 DOI: 10.1002/1878-0261.13285] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 05/23/2022] [Accepted: 07/08/2022] [Indexed: 11/30/2022] Open
Abstract
Increasing evidence demonstrates that DNA damage and genome instability play a crucial role in ageing. Mammalian cells have developed a wide range of complex and well‐orchestrated DNA repair pathways to respond to and resolve many different types of DNA lesions that occur from exogenous and endogenous sources. Defects in these repair pathways lead to accelerated or premature ageing syndromes and increase the likelihood of cancer development. Understanding the fundamental mechanisms of DNA repair will help develop novel strategies to treat ageing‐related diseases. Here, we revisit the processes involved in DNA damage repair and how these can contribute to diseases, including ageing and cancer. We also review recent mechanistic insights into DNA repair and discuss how these insights are being used to develop novel therapeutic strategies for treating human disease. We discuss the use of PARP inhibitors in the clinic for the treatment of breast and ovarian cancer and the challenges associated with acquired drug resistance. Finally, we discuss how DNA repair pathway‐targeted therapeutics are moving beyond PARP inhibition in the search for ever more innovative and efficacious cancer therapies.
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Affiliation(s)
- Thomas L Clarke
- The Massachusetts General Hospital Cancer Center, Harvard Medical School, 02114, Boston, MA, USA.,The Broad Institute of Harvard and MIT, 02142, Cambridge, MA, USA
| | - Raul Mostoslavsky
- The Massachusetts General Hospital Cancer Center, Harvard Medical School, 02114, Boston, MA, USA.,The Broad Institute of Harvard and MIT, 02142, Cambridge, MA, USA
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35
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Characterization of a Novel Heterochromatin Protein 1 Homolog “HP1c” in the Silkworm, Bombyx mori. INSECTS 2022; 13:insects13070631. [PMID: 35886807 PMCID: PMC9316600 DOI: 10.3390/insects13070631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 12/04/2022]
Abstract
Simple Summary Heterochromatin protein 1 (HP1) plays a major role in the formation and maintenance of heterochromatin and in the regulation of gene expression. Five HP1 genes have been found in Drosophila melanogaster and three HP1 genes in Homo sapiens, while in Bombyx mori, two HP1 genes (BmHP1a and BmHP1b) have been reported. In the present study, we analyzed the function of the novel Bombyx mori HP1 gene (BmHP1c), the third HP1 gene in silkworm. BmHP1c has different characteristics from BmHP1a and BmHP1b in terms of transcriptional repression activity, dimer formation, subcellular localization, and effects of RNAi on cell cycle progression. These findings indicate that BmHP1c plays a different role than BmHP1a and BmHP1b. Abstract Heterochromatin protein 1 plays an important role in chromatin structure and gene expression regulation. Three HP1 genes have been found in Homo sapiens, and five HP1 genes have been reported in Drosophila melanogaster. On the other hand, in Bombyx mori, only two HP1 genes, BmHP1a and BmHP1b, were reported. In this research, we have reported the molecular and functional characterization of a novel Bombyx mori HP1 gene (BmHP1c), which had stronger transcriptional repression activity than BmHP1a. BmHP1a and BmHP1b is reported to form homo- and heterodimers, but in co-immunoprecipitation experiments, no homo- or hetero-dimer formation of BmHP1c with the other silkworm HP1s is detected. The intracellular localization of BmHP1c is not only in the nucleus but also in the cytoplasm like mammalian HP1γ. In contrast to human HP1a and b, all three BmHP1s were localized preferentially in the regions poorly stained with DAPI. Interestingly, the double knockdown of BmHP1a and b, but not BmHP1c with a or b, arrested the cell cycle at the G2/M phase. These results suggest that BmHP1c is not essential for cell progression and plays a different role than BmHP1a and BmHP1b.
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Aska EM, Zagidullin B, Pitkänen E, Kauppi L. Single-Cell Mononucleotide Microsatellite Analysis Reveals Differential Insertion-Deletion Dynamics in Mouse T Cells. Front Genet 2022; 13:913163. [PMID: 35873465 PMCID: PMC9304711 DOI: 10.3389/fgene.2022.913163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/06/2022] [Indexed: 11/13/2022] Open
Abstract
Microsatellite sequences are particularly prone to slippage during DNA replication, forming insertion-deletion loops that, if left unrepaired, result in de novo mutations (expansions or contractions of the repeat array). Mismatch repair (MMR) is a critical DNA repair mechanism that corrects these insertion-deletion loops, thereby maintaining microsatellite stability. MMR deficiency gives rise to the molecular phenotype known as microsatellite instability (MSI). By sequencing MMR-proficient and -deficient (Mlh1+/+ and Mlh1−/−) single-cell exomes from mouse T cells, we reveal here several previously unrecognized features of in vivo MSI. Specifically, mutational dynamics of insertions and deletions were different on multiple levels. Factors that associated with propensity of mononucleotide microsatellites to insertions versus deletions were: microsatellite length, nucleotide composition of the mononucleotide tract, gene length and transcriptional status, as well replication timing. Here, we show on a single-cell level that deletions — the predominant MSI type in MMR-deficient cells — are preferentially associated with longer A/T tracts, long or transcribed genes and later-replicating genes.
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Affiliation(s)
- Elli-Mari Aska
- Research Program in Systems Oncology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Bulat Zagidullin
- Research Program in Systems Oncology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Institute for Molecular Medicine Finland (FIMM), HiLIFE, University of Helsinki, Helsinki, Finland
| | - Esa Pitkänen
- Institute for Molecular Medicine Finland (FIMM), HiLIFE, University of Helsinki, Helsinki, Finland
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- iCAN Digital Precision Cancer Medicine Flagship, Helsinki, Finland
| | - Liisa Kauppi
- Research Program in Systems Oncology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- *Correspondence: Liisa Kauppi,
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Dsouza KB, Li AY, Bhargava VK, Libbrecht MW. Latent Representation of the Human Pan-Celltype Epigenome Through a Deep Recurrent Neural Network. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2022; 19:2313-2323. [PMID: 34043510 DOI: 10.1109/tcbb.2021.3084147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The availability of thousands of assays of epigenetic activity necessitates compressed representations of these data sets that summarize the epigenetic landscape of the genome. Until recently, most such representations were cell type-specific, applying to a single tissue or cell state. Recently, neural networks have made it possible to summarize data across tissues to produce a pan-cell type representation. In this work, we propose Epi-LSTM, a deep long short-term memory (LSTM) recurrent neural network autoencoder to capture the long-term dependencies in the epigenomic data. The latent representations from Epi-LSTM capture a variety of genomic phenomena, including gene-expression, promoter-enhancer interactions, replication timing, frequently interacting regions, and evolutionary conservation. These representations outperform existing methods in a majority of cell types while yielding smoother representations along the genomic axis due to their sequential nature.
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Dsouza KB, Maslova A, Al-Jibury E, Merkenschlager M, Bhargava VK, Libbrecht MW. Learning representations of chromatin contacts using a recurrent neural network identifies genomic drivers of conformation. Nat Commun 2022; 13:3704. [PMID: 35764630 PMCID: PMC9240038 DOI: 10.1038/s41467-022-31337-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 06/15/2022] [Indexed: 11/28/2022] Open
Abstract
Despite the availability of chromatin conformation capture experiments, discerning the relationship between the 1D genome and 3D conformation remains a challenge, which limits our understanding of their affect on gene expression and disease. We propose Hi-C-LSTM, a method that produces low-dimensional latent representations that summarize intra-chromosomal Hi-C contacts via a recurrent long short-term memory neural network model. We find that these representations contain all the information needed to recreate the observed Hi-C matrix with high accuracy, outperforming existing methods. These representations enable the identification of a variety of conformation-defining genomic elements, including nuclear compartments and conformation-related transcription factors. They furthermore enable in-silico perturbation experiments that measure the influence of cis-regulatory elements on conformation.
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Affiliation(s)
- Kevin B Dsouza
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, Canada.
| | - Alexandra Maslova
- School of Computing Science, Simon Fraser University, Burnaby, Canada
| | - Ediem Al-Jibury
- MRC, London Institute of Medical Sciences, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, UK
- Department of Computing, Imperial College London, London, UK
| | - Matthias Merkenschlager
- MRC, London Institute of Medical Sciences, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Vijay K Bhargava
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, Canada
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Dimerization of Firing Factors for Replication Origin Activation in Eukaryotes: A Crucial Process for Simultaneous Assembly of Bidirectional Replication Forks? BIOLOGY 2022; 11:biology11060928. [PMID: 35741449 PMCID: PMC9219616 DOI: 10.3390/biology11060928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/13/2022] [Accepted: 06/15/2022] [Indexed: 11/17/2022]
Abstract
Simple Summary Chromosomal DNA must be faithfully duplicated and segregated into two daughter cells when cells divide. DNA synthesis initiates from specific regions known as the origins of replication. When it starts, a pair of the replication fork is established, and each replication fork moves away from replication origins. In each replication fork, replicative helicase unwinds DNA from a double to a single strand. This implies that two sets of active helicase are generated from each replication origin. To make this possible, two sets of replicative helicases are loaded onto replication origins as inactive dimers first. When S-phase specific cyclin-dependent kinases, S-CDKs, are activated, the inactive helicase is converted into the active helicase with the aid of other factors called firing factors. Although two sets of firing factors seem to be required to activate two sets of helicase, it is largely unknown whether two sets of firing factors function simultaneously to establish bidirectional replication forks in a coordinated way. We introduce our current understanding of firing factor dimerization and discuss its potential contribution to bidirectional replication fork formation in this review. Abstract Controlling the activity of the heterohexameric Mcm2–7 replicative helicase is crucial for regulation of replication origin activity in eukaryotes. Because bidirectional replication forks are generated from every replication origin, when origins are licensed for replication in the first step of DNA replication, two inactive Mcm2–7 heterohexiameric complexes are loaded around double stranded DNA as a head-to-head double hexamer. The helicases are subsequently activated via a ‘firing’ reaction, in which the Mcm2–7 double hexamer is converted into two active helicase units, the CMG complex, by firing factors. Dimerization of firing factors may contribute to this process by allowing simultaneous activation of two sets of helicases and thus efficient assembly of bidirectional replication forks. An example of this is dimerization of the firing factor Sld3/Treslin/Ticrr via its binding partner, Sld7/MTBP. In organisms in which no Sld7 ortholog has been identified, such as the fission yeast Schizosaccharomyces pombe, Sld3 itself has a dimerization domain, and it has been suggested that this self-interaction is crucial for the firing reaction in this organism. Dimerization induces a conformational change in Sdl3 that appears to be critical for the firing reaction. Moreover, Mcm10 also seems to be regulated by self-interaction in yeasts. Although it is not yet clear to what extent dimerization of firing factors contributes to the firing reaction in eukaryotes, we discuss the possible roles of firing factor dimerization in simultaneous helicase activation.
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Massey DJ, Koren A. Telomere-to-telomere human DNA replication timing profiles. Sci Rep 2022; 12:9560. [PMID: 35688856 PMCID: PMC9187705 DOI: 10.1038/s41598-022-13638-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 05/26/2022] [Indexed: 11/23/2022] Open
Abstract
The spatiotemporal organization of DNA replication produces a highly robust and reproducible replication timing profile. Sequencing-based methods for assaying replication timing genome-wide have become commonplace, but regions of high repeat content in the human genome have remained refractory to analysis. Here, we report the first nearly-gapless telomere-to-telomere replication timing profiles in human, using the T2T-CHM13 genome assembly and sequencing data for five cell lines. We find that replication timing can be successfully assayed in centromeres and large blocks of heterochromatin. Centromeric regions replicate in mid-to-late S-phase and contain replication-timing peaks at a similar density to other genomic regions, while distinct families of heterochromatic satellite DNA differ in their bias for replicating in late S-phase. The high degree of consistency in centromeric replication timing across chromosomes within each cell line prompts further investigation into the mechanisms dictating that some cell lines replicate their centromeres earlier than others, and what the consequences of this variation are.
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Affiliation(s)
- Dashiell J Massey
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Amnon Koren
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA.
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Zaffar E, Ferreira P, Sanchez-Pulido L, Boos D. The Role of MTBP as a Replication Origin Firing Factor. BIOLOGY 2022; 11:biology11060827. [PMID: 35741348 PMCID: PMC9219753 DOI: 10.3390/biology11060827] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/20/2022] [Accepted: 05/22/2022] [Indexed: 12/12/2022]
Abstract
The initiation step of replication at replication origins determines when and where in the genome replication machines, replisomes, are generated. Tight control of replication initiation helps facilitate the two main tasks of genome replication, to duplicate the genome accurately and exactly once each cell division cycle. The regulation of replication initiation must ensure that initiation occurs during the S phase specifically, that no origin fires more than once per cell cycle, that enough origins fire to avoid non-replicated gaps, and that the right origins fire at the right time but only in favorable circumstances. Despite its importance for genetic homeostasis only the main molecular processes of eukaryotic replication initiation and its cellular regulation are understood. The MTBP protein (Mdm2-binding protein) is so far the last core replication initiation factor identified in metazoan cells. MTBP is the orthologue of yeast Sld7. It is essential for origin firing, the maturation of pre-replicative complexes (pre-RCs) into replisomes, and is emerging as a regulation focus targeted by kinases and by regulated degradation. We present recent insight into the structure and cellular function of the MTBP protein in light of recent structural and biochemical studies revealing critical molecular details of the eukaryotic origin firing reaction. How the roles of MTBP in replication and other cellular processes are mutually connected and are related to MTBP's contribution to tumorigenesis remains largely unclear.
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Affiliation(s)
- Eman Zaffar
- Molecular Genetics II, Centre for Medical Biotechnology, University of Duisburg-Essen, 45141 Essen, Germany; (E.Z.); (P.F.)
| | - Pedro Ferreira
- Molecular Genetics II, Centre for Medical Biotechnology, University of Duisburg-Essen, 45141 Essen, Germany; (E.Z.); (P.F.)
| | - Luis Sanchez-Pulido
- Medical Research Council Human Genetics Unit, IGC, University of Edinburgh, Edinburgh EH9 3JR, UK;
| | - Dominik Boos
- Molecular Genetics II, Centre for Medical Biotechnology, University of Duisburg-Essen, 45141 Essen, Germany; (E.Z.); (P.F.)
- Correspondence: ; Tel.: +49-201-183-4132
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Ranjan R, Snedeker J, Wooten M, Chu C, Bracero S, Mouton T, Chen X. Differential condensation of sister chromatids acts with Cdc6 to ensure asynchronous S-phase entry in Drosophila male germline stem cell lineage. Dev Cell 2022; 57:1102-1118.e7. [PMID: 35483360 PMCID: PMC9134767 DOI: 10.1016/j.devcel.2022.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 01/16/2022] [Accepted: 04/05/2022] [Indexed: 01/06/2023]
Abstract
During Drosophila melanogaster male germline stem cell (GSC) asymmetric division, preexisting old versus newly synthesized histones H3 and H4 are asymmetrically inherited. However, the biological outcomes of this phenomenon have remained unclear. Here, we tracked old and new histones throughout the GSC cell cycle through the use of high spatial and temporal resolution microscopy. We found unique features that differ between old and new histone-enriched sister chromatids, including differences in nucleosome density, chromosomal condensation, and H3 Ser10 phosphorylation. These distinct chromosomal features lead to their differential association with Cdc6, a pre-replication complex component, and subsequent asynchronous DNA replication initiation in the resulting daughter cells. Disruption of asymmetric histone inheritance abolishes differential Cdc6 association and asynchronous S-phase entry, demonstrating that histone asymmetry acts upstream of these critical cell-cycle progression events. Furthermore, disruption of these GSC-specific chromatin features leads to GSC defects, indicating a connection between histone inheritance, cell-cycle progression, and cell fate determination.
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Affiliation(s)
- Rajesh Ranjan
- Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Jonathan Snedeker
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Matthew Wooten
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Carolina Chu
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sabrina Bracero
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Taylar Mouton
- Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Xin Chen
- Howard Hughes Medical Institute, Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, The Johns Hopkins University, Baltimore, MD 21218, USA.
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S Phase Duration Is Determined by Local Rate and Global Organization of Replication. BIOLOGY 2022; 11:biology11050718. [PMID: 35625446 PMCID: PMC9139170 DOI: 10.3390/biology11050718] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 04/29/2022] [Accepted: 05/03/2022] [Indexed: 11/17/2022]
Abstract
Simple Summary In order for a cell to divide into two cells, it must first copy its DNA. Although the time required for this process tends not to vary much, many examples of the importance of variability have been reported. In this review, we discuss the methods used to study this question, present some of the examples of variation, and attempt to explain the factors that determine the time required in simple terms. We will show that the overall time depends on the rate of DNA replication within a region, and on the temporal organization of the regions relative to each other. Abstract The duration of the cell cycle has been extensively studied and a wide degree of variability exists between cells, tissues and organisms. However, the duration of S phase has often been neglected, due to the false assumption that S phase duration is relatively constant. In this paper, we describe the methodologies to measure S phase duration, summarize the existing knowledge about its variability and discuss the key factors that control it. The local rate of replication (LRR), which is a combination of fork rate (FR) and inter-origin distance (IOD), has a limited influence on S phase duration, partially due to the compensation between FR and IOD. On the other hand, the organization of the replication program, specifically the amount of replication domains that fire simultaneously and the degree of overlap between the firing of distinct replication timing domains, is the main determinant of S phase duration. We use these principles to explain the variation in S phase length in different tissues and conditions.
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Escobar TM, Yu JR, Liu S, Lucero K, Vasilyev N, Nudler E, Reinberg D. Inheritance of repressed chromatin domains during S phase requires the histone chaperone NPM1. SCIENCE ADVANCES 2022; 8:eabm3945. [PMID: 35476441 PMCID: PMC9045712 DOI: 10.1126/sciadv.abm3945] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 03/09/2022] [Indexed: 06/14/2023]
Abstract
The epigenetic process safeguards cell identity during cell division through the inheritance of appropriate gene expression profiles. We demonstrated previously that parental nucleosomes are inherited by the same chromatin domains during DNA replication only in the case of repressed chromatin. We now show that this specificity is conveyed by NPM1, a histone H3/H4 chaperone. Proteomic analyses of late S-phase chromatin revealed NPM1 in association with both H3K27me3, an integral component of facultative heterochromatin, and MCM2, an integral component of the DNA replication machinery; moreover, NPM1 interacts directly with PRC2 and with MCM2. Given that NPM1 is essential, the inheritance of repressed chromatin domains was examined anew using mESCs expressing an auxin-degradable version of endogenous NPM1. Upon NPM1 degradation, cells accumulated in the G1-S phase of the cell cycle and parental nucleosome inheritance from repressed chromatin domains was markedly compromised. NPM1 chaperone activity may contribute to the integrity of this process as appropriate inheritance required the NPM1 acidic patches.
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Affiliation(s)
- Thelma M. Escobar
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA
- Howard Hughes Medical Institute, New York University Grossman School of Medicine, New York, NY, USA
| | - Jia-Ray Yu
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA
- Howard Hughes Medical Institute, New York University Grossman School of Medicine, New York, NY, USA
| | - Sanxiong Liu
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA
- Howard Hughes Medical Institute, New York University Grossman School of Medicine, New York, NY, USA
| | - Kimberly Lucero
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA
- Howard Hughes Medical Institute, New York University Grossman School of Medicine, New York, NY, USA
| | - Nikita Vasilyev
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA
- Howard Hughes Medical Institute, New York University Grossman School of Medicine, New York, NY, USA
| | - Evgeny Nudler
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA
- Howard Hughes Medical Institute, New York University Grossman School of Medicine, New York, NY, USA
| | - Danny Reinberg
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA
- Howard Hughes Medical Institute, New York University Grossman School of Medicine, New York, NY, USA
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Ali MZ, Farid A, Ahmad S, Muzammal M, Mohaini MA, Alsalman AJ, Al Hawaj MA, Alhashem YN, Alsaleh AA, Almusalami EM, Maryam M, Khan MA. In Silico Analysis Identified Putative Pathogenic Missense nsSNPs in Human SLITRK1 Gene. Genes (Basel) 2022; 13:672. [PMID: 35456478 PMCID: PMC9030497 DOI: 10.3390/genes13040672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 04/05/2022] [Accepted: 04/07/2022] [Indexed: 02/04/2023] Open
Abstract
Human DNA contains several variations, which can affect the structure and normal functioning of a protein. These variations could be single nucleotide polymorphisms (SNPs) or insertion-deletions (InDels). SNPs, as opposed to InDels, are more commonly present in DNA and may cause genetic disorders. In the current study, several bioinformatic tools were used to prioritize the pathogenic variants in the SLITRK1 gene. Out of all of the variants, 16 were commonly predicted to be pathogenic by these tools. All the variants had very low frequency, i.e., <0.0001 in the global population. The secondary structure of all filtered variants was predicted, but no structural change was observed at the site of variation in any variant. Protein stability analysis of these variants was then performed, which determined a decrease in protein stability of 10 of the variants. Amino acid conservation analysis revealed that all the amino acids were highly conserved, indicating their structural and functional importance. Protein 3D structure of wildtype SLITRK1 and all of its variants was predicted using I-TASSER, and the effect of variation on 3D structure of the protein was observed using the Missense3D tool, which presented the probable structural loss in three variants, i.e., Asn529Lys, Leu496Pro and Leu94Phe. The wildtype SLITRK1 protein and these three variants were independently docked with their close interactor protein PTPRD, and remarkable differences were observed in the docking sites of normal and variants, which will ultimately affect the functional activity of the SLITRK1 protein. Previous studies have shown that mutations in SLITRK1 are involved in Tourette syndrome. The present study may assist a molecular geneticist in interpreting the variant pathogenicity in research as well as diagnostic setup.
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Affiliation(s)
- Muhammad Zeeshan Ali
- Gomal Center of Biochemistry and Biotechnology, Gomal University, Dera Ismail Khan 29111, Pakistan; (M.Z.A.); (A.F.); (S.A.); (M.M.)
| | - Arshad Farid
- Gomal Center of Biochemistry and Biotechnology, Gomal University, Dera Ismail Khan 29111, Pakistan; (M.Z.A.); (A.F.); (S.A.); (M.M.)
| | - Safeer Ahmad
- Gomal Center of Biochemistry and Biotechnology, Gomal University, Dera Ismail Khan 29111, Pakistan; (M.Z.A.); (A.F.); (S.A.); (M.M.)
| | - Muhammad Muzammal
- Gomal Center of Biochemistry and Biotechnology, Gomal University, Dera Ismail Khan 29111, Pakistan; (M.Z.A.); (A.F.); (S.A.); (M.M.)
| | - Mohammed Al Mohaini
- Basic Sciences Department, College of Applied Medical Sciences, King Saud Bin Abdulaziz University for Health Sciences, Al Ahsa 31982, Saudi Arabia;
- King Abdullah International Medical Research Center, Al Ahsa 31982, Saudi Arabia
| | - Abdulkhaliq J. Alsalman
- Department of Clinical Pharmacy, Faculty of Pharmacy, Northern Border University, Rafha 91911, Saudi Arabia;
| | - Maitham A. Al Hawaj
- Department of Pharmacy Practice, College of Clinical Pharmacy, King Faisal University, Al Ahsa 31982, Saudi Arabia;
| | - Yousef N. Alhashem
- Clinical Laboratory Sciences Department, Mohammed Al-Mana College for Medical Sciences, Dammam 34222, Saudi Arabia; (Y.N.A.); (A.A.A.)
| | - Abdulmonem A. Alsaleh
- Clinical Laboratory Sciences Department, Mohammed Al-Mana College for Medical Sciences, Dammam 34222, Saudi Arabia; (Y.N.A.); (A.A.A.)
| | | | - Mahpara Maryam
- Department of Zoology, Government College No.1, Dera Ismail Khan 29111, Pakistan;
| | - Muzammil Ahmad Khan
- Gomal Center of Biochemistry and Biotechnology, Gomal University, Dera Ismail Khan 29111, Pakistan; (M.Z.A.); (A.F.); (S.A.); (M.M.)
- Department of Human Genetics, Sidra Medical and Research Centre, Doha 26999, Qatar
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Richards L, Das S, Nordman JT. Rif1-Dependent Control of Replication Timing. Genes (Basel) 2022; 13:genes13030550. [PMID: 35328102 PMCID: PMC8955891 DOI: 10.3390/genes13030550] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/15/2022] [Accepted: 03/18/2022] [Indexed: 02/01/2023] Open
Abstract
Successful duplication of the genome requires the accurate replication of billions of base pairs of DNA within a relatively short time frame. Failure to accurately replicate the genome results in genomic instability and a host of diseases. To faithfully and rapidly replicate the genome, DNA replication must be tightly regulated and coordinated with many other nuclear processes. These regulations, however, must also be flexible as replication kinetics can change through development and differentiation. Exactly how DNA replication is regulated and how this regulation changes through development is an active field of research. One aspect of genome duplication where much remains to be discovered is replication timing (RT), which dictates when each segment of the genome is replicated during S phase. All organisms display some level of RT, yet the precise mechanisms that govern RT remain are not fully understood. The study of Rif1, a protein that actively regulates RT from yeast to humans, provides a key to unlock the underlying molecular mechanisms controlling RT. The paradigm for Rif1 function is to delay helicase activation within certain regions of the genome, causing these regions to replicate late in S phase. Many questions, however, remain about the intricacies of Rif1 function. Here, we review the current models for the activity of Rif1 with the goal of trying to understand how Rif1 functions to establish the RT program.
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Chemically Induced Chromosomal Interaction (CICI) method to study chromosome dynamics and its biological roles. Nat Commun 2022; 13:757. [PMID: 35140210 PMCID: PMC8828778 DOI: 10.1038/s41467-022-28416-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 01/14/2022] [Indexed: 01/01/2023] Open
Abstract
Numerous intra- and inter-chromosomal contacts have been mapped in eukaryotic genomes, but it remains challenging to link these 3D structures to their regulatory functions. To establish the causal relationships between chromosome conformation and genome functions, we develop a method, Chemically Induced Chromosomal Interaction (CICI), to selectively perturb the chromosome conformation at targeted loci. Using this method, long-distance chromosomal interactions can be induced dynamically between intra- or inter-chromosomal loci pairs, including the ones with very low Hi-C contact frequencies. Measurement of CICI formation time allows us to probe chromosome encounter dynamics between different loci pairs across the cell cycle. We also conduct two functional tests of CICI. We perturb the chromosome conformation near a DNA double-strand break and observe altered donor preference in homologous recombination; we force interactions between early and late-firing DNA replication origins and find no significant changes in replication timing. These results suggest that chromosome conformation plays a deterministic role in homology-directed DNA repair, but not in the establishment of replication timing. Overall, our study demonstrates that CICI is a powerful tool to study chromosome dynamics and 3D genome function. Methods to selectively manipulate specific long-distance chromosomal interactions are limited. Here the authors develop a method called Chemically Induced Chromosomal Interaction (CICI) to engineer interactions and demonstrate that 3D conformation plays a causal role in establishing donor DNA preference during DNA repair.
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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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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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Liu J, Yang M, Zhao W, Zhou X. CCPE: cell cycle pseudotime estimation for single cell RNA-seq data. Nucleic Acids Res 2022; 50:704-716. [PMID: 34931240 PMCID: PMC8789092 DOI: 10.1093/nar/gkab1236] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 11/22/2021] [Accepted: 12/15/2021] [Indexed: 11/25/2022] Open
Abstract
Pseudotime analysis from scRNA-seq data enables to characterize the continuous progression of various biological processes, such as the cell cycle. Cell cycle plays an important role in cell fate decisions and differentiation and is often regarded as a confounder in scRNA-seq data analysis when analyzing the role of other factors. Therefore, accurate prediction of cell cycle pseudotime and identification of cell cycle stages are important steps for characterizing the development-related biological processes. Here, we develop CCPE, a novel cell cycle pseudotime estimation method to characterize cell cycle timing and identify cell cycle phases from scRNA-seq data. CCPE uses a discriminative helix to characterize the circular process of the cell cycle and estimates each cell's pseudotime along the cell cycle. We evaluated the performance of CCPE based on a variety of simulated and real scRNA-seq datasets. Our results indicate that CCPE is an effective method for cell cycle estimation and competitive in various applications compared with other existing methods. CCPE successfully identified cell cycle marker genes and is robust to dropout events in scRNA-seq data. Accurate prediction of the cell cycle using CCPE can also effectively facilitate the removal of cell cycle effects across cell types or conditions.
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Affiliation(s)
- Jiajia Liu
- College of Electronic and Information Engineering, Tongji University, Shanghai, Shanghai 201804, China
- Center for Computational Systems Medicine, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Mengyuan Yang
- Center for Computational Systems Medicine, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Weiling Zhao
- Center for Computational Systems Medicine, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Xiaobo Zhou
- Center for Computational Systems Medicine, School of Biomedical Informatics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- School of Dentistry, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
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