1
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Selvam K, Wyrick JJ, Parra MA. DNA Repair in Nucleosomes: Insights from Histone Modifications and Mutants. Int J Mol Sci 2024; 25:4393. [PMID: 38673978 PMCID: PMC11050016 DOI: 10.3390/ijms25084393] [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: 02/17/2024] [Revised: 04/08/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
DNA repair pathways play a critical role in genome stability, but in eukaryotic cells, they must operate to repair DNA lesions in the compact and tangled environment of chromatin. Previous studies have shown that the packaging of DNA into nucleosomes, which form the basic building block of chromatin, has a profound impact on DNA repair. In this review, we discuss the principles and mechanisms governing DNA repair in chromatin. We focus on the role of histone post-translational modifications (PTMs) in repair, as well as the molecular mechanisms by which histone mutants affect cellular sensitivity to DNA damage agents and repair activity in chromatin. Importantly, these mechanisms are thought to significantly impact somatic mutation rates in human cancers and potentially contribute to carcinogenesis and other human diseases. For example, a number of the histone mutants studied primarily in yeast have been identified as candidate oncohistone mutations in different cancers. This review highlights these connections and discusses the potential importance of DNA repair in chromatin to human health.
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Affiliation(s)
- Kathiresan Selvam
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
| | - John J. Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
| | - Michael A. Parra
- Department of Chemistry, Susquehanna University, Selinsgrove, PA 17870, USA
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2
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Wilson HE, Wyrick JJ. Genome-wide impact of cytosine methylation and DNA sequence context on UV-induced CPD formation. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2024; 65 Suppl 1:14-24. [PMID: 37554110 PMCID: PMC10853481 DOI: 10.1002/em.22569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/14/2023] [Accepted: 08/07/2023] [Indexed: 08/10/2023]
Abstract
Exposure to ultraviolet (UV) light is the primary etiological agent for skin cancers because UV damages cellular DNA. The most frequent form of UV damage is the cyclobutane pyrimidine dimer (CPD), which consists of covalent linkages between neighboring pyrimidine bases in DNA. In human cells, the 5' position of cytosine bases in CG dinucleotides is frequently methylated, and methylated cytosines in the TP53 tumor suppressor are often sites of mutation hotspots in skin cancers. It has been argued that this is because cytosine methylation promotes UV-induced CPD formation; however, the effects of cytosine methylation on CPD formation are controversial, with conflicting results from previous studies. Here, we use a genome-wide method known as CPD-seq to map UVB- and UVC-induced CPDs across the yeast genome in the presence or absence in vitro methylation by the CpG methyltransferase M.SssI. Our data indicate that cytosine methylation increases UVB-induced CPD formation nearly 2-fold relative to unmethylated DNA, but the magnitude of induction depends on the flanking sequence context. Sequence contexts with a 5' guanine base (e.g., GCCG and GTCG) show the strongest induction due to cytosine methylation, potentially because these sequence contexts are less efficient at forming CPD lesions in the absence of methylation. We show that cytosine methylation also modulates UVC-induced CPD formation, albeit to a lesser extent than UVB. These findings can potentially reconcile previous studies, and define the impact of cytosine methylation on UV damage across a eukaryotic genome.
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Affiliation(s)
- Hannah E. Wilson
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
| | - John J. Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
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3
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Morledge-Hampton B, Kalyanaraman A, Wyrick JJ. Analysis of cytosine deamination events in excision repair sequencing reads reveals mechanisms of incision site selection in NER. Nucleic Acids Res 2024; 52:1720-1735. [PMID: 38109317 PMCID: PMC10899786 DOI: 10.1093/nar/gkad1195] [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: 05/17/2023] [Revised: 11/28/2023] [Accepted: 12/01/2023] [Indexed: 12/20/2023] Open
Abstract
Nucleotide excision repair (NER) removes helix-distorting DNA lesions and is therefore critical for genome stability. During NER, DNA is unwound on either side of the lesion and excised, but the rules governing incision site selection, particularly in eukaryotic cells, are unclear. Excision repair-sequencing (XR-seq) sequences excised NER fragments, but analysis has been limited because the lesion location is unknown. Here, we exploit accelerated cytosine deamination rates in UV-induced CPD (cyclobutane pyrimidine dimer) lesions to precisely map their locations at C to T mismatches in XR-seq reads, revealing general and species-specific patterns of incision site selection during NER. Our data indicate that the 5' incision site occurs preferentially in HYV (i.e. not G; C/T; not T) sequence motifs, a pattern that can be explained by sequence preferences of the XPF-ERCC1 endonuclease. In contrast, the 3' incision site does not show strong sequence preferences, once truncated reads arising from mispriming events are excluded. Instead, the 3' incision is partially determined by the 5' incision site distance, indicating that the two incision events are coupled. Finally, our data reveal unique and coupled NER incision patterns at nucleosome boundaries. These findings reveal key principles governing NER incision site selection in eukaryotic cells.
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Affiliation(s)
| | - Ananth Kalyanaraman
- School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA 99164, USA
| | - John J Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
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4
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Otlu B, Alexandrov LB. Evaluating topography of mutational signatures with SigProfilerTopography. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.08.574683. [PMID: 38260507 PMCID: PMC10802511 DOI: 10.1101/2024.01.08.574683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The mutations found in a cancer genome are shaped by diverse processes, each displaying a characteristic mutational signature that may be influenced by the genome's architecture. While prior analyses have evaluated the effect of topographical genomic features on mutational signatures, there has been no computational tool that can comprehensively examine this interplay. Here, we present SigProfilerTopography, a Python package that allows evaluating the effect of chromatin organization, histone modifications, transcription factor binding, DNA replication, and DNA transcription on the activities of different mutational processes. SigProfilerTopography elucidates the unique topographical characteristics of mutational signatures, unveiling their underlying biological and molecular mechanisms.
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Affiliation(s)
- Burçak Otlu
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA, 92093, USA
- Department of Bioengineering, UC San Diego, La Jolla, CA, 92093, USA
- Moores Cancer Center, UC San Diego, La Jolla, CA, 92037, USA
- Department of Health Informatics, Graduate School of Informatics, Middle East Technical University, 06800, Ankara, Turkey
| | - Ludmil B. Alexandrov
- Department of Cellular and Molecular Medicine, UC San Diego, La Jolla, CA, 92093, USA
- Department of Bioengineering, UC San Diego, La Jolla, CA, 92093, USA
- Moores Cancer Center, UC San Diego, La Jolla, CA, 92037, USA
- Sanford Stem Cell Institute, University of California San Diego, La Jolla, CA 92037
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5
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Cohen Y, Adar S. Novel insights into bulky DNA damage formation and nucleotide excision repair from high-resolution genomics. DNA Repair (Amst) 2023; 130:103549. [PMID: 37566959 DOI: 10.1016/j.dnarep.2023.103549] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/27/2023] [Accepted: 07/28/2023] [Indexed: 08/13/2023]
Abstract
DNA damages compromise cell function and fate. Cells of all organisms activate a global DNA damage response that includes a signaling stress response, activation of checkpoints, and recruitment of repair enzymes. Especially deleterious are bulky, helix-distorting damages that block transcription and replication. Due to their miscoding nature, these damages lead to mutations and cancer. In human cells, bulky DNA damages are repaired by nucleotide excision repair (NER). To date, the basic mechanism of NER in naked DNA is well defined. Still, there is a fundamental gap in our understanding of how repair is orchestrated despite the packaging of DNA in chromatin, and how it is coordinated with active transcription and replication. The last decade has brought forth huge advances in our ability to detect and assay bulky DNA damages and their repair at single nucleotide resolution across the human genome. Here we review recent findings on the effect of chromatin and DNA-binding proteins on the formation of bulky DNA damages, and novel insights on NER, provided by the recent application of genomic methods.
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Affiliation(s)
- Yuval Cohen
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel
| | - Sheera Adar
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel.
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6
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Liu C, Wang Z, Wang J, Liu C, Wang M, Ngo V, Wang W. Predicting regional somatic mutation rates using DNA motifs. PLoS Comput Biol 2023; 19:e1011536. [PMID: 37782656 PMCID: PMC10569533 DOI: 10.1371/journal.pcbi.1011536] [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: 04/02/2023] [Revised: 10/12/2023] [Accepted: 09/20/2023] [Indexed: 10/04/2023] Open
Abstract
How the locus-specificity of epigenetic modifications is regulated remains an unanswered question. A contributing mechanism is that epigenetic enzymes are recruited to specific loci by DNA binding factors recognizing particular sequence motifs (referred to as epi-motifs). Using these motifs to predict biological outputs depending on local epigenetic state such as somatic mutation rates would confirm their functionality. Here, we used DNA motifs including known TF motifs and epi-motifs as a surrogate of epigenetic signals to predict somatic mutation rates in 13 cancers at an average 23kbp resolution. We implemented an interpretable neural network model, called contextual regression, to successfully learn the universal relationship between mutations and DNA motifs, and uncovered motifs that are most impactful on the regional mutation rates such as TP53 and epi-motifs associated with H3K9me3. Furthermore, we identified genomic regions with significantly higher mutation rates than the expected values in each individual tumor and demonstrated that such cancer-related regions can accurately predict cancer types. Interestingly, we found that the same mutation signatures often have different contributions to cancer-related and cancer-independent regions, and we also identified the motifs with the most contribution to each mutation signature.
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Affiliation(s)
- Cong Liu
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
| | - Zengmiao Wang
- State Key Laboratory of Remote Sensing Science, Center for Global Change and Public Health, Faculty of Geographical Science, Beijing Normal University, Beijing, China
| | - Jun Wang
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
| | - Chengyu Liu
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
| | - Mengchi Wang
- Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, California, United States of America
| | - Vu Ngo
- Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, California, United States of America
| | - Wei Wang
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
- Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, California, United States of America
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California, United States of America
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7
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Smerdon MJ, Wyrick JJ, Delaney S. A half century of exploring DNA excision repair in chromatin. J Biol Chem 2023; 299:105118. [PMID: 37527775 PMCID: PMC10498010 DOI: 10.1016/j.jbc.2023.105118] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 07/23/2023] [Accepted: 07/25/2023] [Indexed: 08/03/2023] Open
Abstract
DNA in eukaryotic cells is packaged into the compact and dynamic structure of chromatin. This packaging is a double-edged sword for DNA repair and genomic stability. Chromatin restricts the access of repair proteins to DNA lesions embedded in nucleosomes and higher order chromatin structures. However, chromatin also serves as a signaling platform in which post-translational modifications of histones and other chromatin-bound proteins promote lesion recognition and repair. Similarly, chromatin modulates the formation of DNA damage, promoting or suppressing lesion formation depending on the chromatin context. Therefore, the modulation of DNA damage and its repair in chromatin is crucial to our understanding of the fate of potentially mutagenic and carcinogenic lesions in DNA. Here, we survey many of the landmark findings on DNA damage and repair in chromatin over the last 50 years (i.e., since the beginning of this field), focusing on excision repair, the first repair mechanism studied in the chromatin landscape. For example, we highlight how the impact of chromatin on these processes explains the distinct patterns of somatic mutations observed in cancer genomes.
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Affiliation(s)
- Michael J Smerdon
- Biochemistry and Biophysics, School of Molecular Biosciences, Washington State University, Pullman, Washington, USA.
| | - John J Wyrick
- Genetics and Cell Biology, School of Molecular Biosciences, Washington State University, Pullman, Washington, USA
| | - Sarah Delaney
- Department of Chemistry, Brown University, Providence, Rhode Island, USA
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8
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Bohm KA, Morledge-Hampton B, Stevison S, Mao P, Roberts SA, Wyrick JJ. Genome-wide maps of rare and atypical UV photoproducts reveal distinct patterns of damage formation and mutagenesis in yeast chromatin. Proc Natl Acad Sci U S A 2023; 120:e2216907120. [PMID: 36853943 PMCID: PMC10013872 DOI: 10.1073/pnas.2216907120] [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: 10/03/2022] [Accepted: 02/03/2023] [Indexed: 03/01/2023] Open
Abstract
Ultraviolet (UV) light induces different classes of mutagenic photoproducts in DNA, namely cyclobutane pyrimidine dimers (CPDs), 6-4 photoproducts (6-4PPs), and atypical thymine-adenine photoproducts (TA-PPs). CPD formation is modulated by nucleosomes and transcription factors (TFs), which has important ramifications for Ultraviolet (UV) mutagenesis. How chromatin affects the formation of 6-4PPs and TA-PPs is unclear. Here, we use UV damage endonuclease-sequencing (UVDE-seq) to map these UV photoproducts across the yeast genome. Our results indicate that nucleosomes, the fundamental building block of chromatin, have opposing effects on photoproduct formation. Nucleosomes induce CPDs and 6-4PPs at outward rotational settings in nucleosomal DNA but suppress TA-PPs at these settings. Our data also indicate that DNA binding by different classes of yeast TFs causes lesion-specific hotspots of 6-4PPs or TA-PPs. For example, DNA binding by the TF Rap1 generally suppresses CPD and 6-4PP formation but induces a TA-PP hotspot. Finally, we show that 6-4PP formation is strongly induced at the binding sites of TATA-binding protein (TBP), which is correlated with higher mutation rates in UV-exposed yeast. These results indicate that the formation of 6-4PPs and TA-PPs is modulated by chromatin differently than CPDs and that this may have important implications for UV mutagenesis.
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Affiliation(s)
- Kaitlynne A. Bohm
- School of Molecular Biosciences, Washington State University, Pullman, WA99164
| | | | - Scott Stevison
- School of Molecular Biosciences, Washington State University, Pullman, WA99164
| | - Peng Mao
- Department of Internal Medicine, University of New Mexico Comprehensive Cancer Center, Albuquerque, NM87131
| | - Steven A. Roberts
- School of Molecular Biosciences, Washington State University, Pullman, WA99164
- Center for Reproductive Biology, Washington State University, Pullman, WA99164
| | - John J. Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA99164
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9
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Bohm KA, Wyrick JJ. Damage mapping techniques and the light they have shed on canonical and atypical UV photoproducts. Front Genet 2023; 13:1102593. [PMID: 36704334 PMCID: PMC9871259 DOI: 10.3389/fgene.2022.1102593] [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: 11/19/2022] [Accepted: 12/20/2022] [Indexed: 01/11/2023] Open
Abstract
Ultraviolet (UV) light is a pervasive threat to the DNA of terrestrial organisms. UV light induces helix-distorting DNA lesions, primarily cyclobutane pyrimidine dimers (CPDs) that form between neighboring pyrimidine bases. Unrepaired CPD lesions cause cytosine-to-thymine (C>T) substitutions in dipyrimidine sequences, which is the predominant mutation class in skin cancer genomes. However, many driver mutations in melanoma (e.g., in the BRAF and NRAS oncogenes) do not fit this UV mutation signature. Recent studies have brought to light the intriguing hypothesis that these driver mutations may be induced by infrequent or atypical UV photoproducts, including pyrimidine 6-4 pyrimidone photoproducts (6-4PP) and thymine-adenine (TA) photoproducts. Here, we review innovative methods for mapping both canonical and atypical UV-induced photoproducts across the genome.
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Affiliation(s)
- Kaitlynne A. Bohm
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States
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10
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Pokusaeva VO, Diez AR, Espinar L, Pérez AT, Filion GJ. Strand asymmetry influences mismatch resolution during a single-strand annealing. Genome Biol 2022; 23:93. [PMID: 35414014 PMCID: PMC9001825 DOI: 10.1186/s13059-022-02665-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/30/2022] [Indexed: 02/08/2023] Open
Abstract
Background Biases of DNA repair can shape the nucleotide landscape of genomes at evolutionary timescales. The molecular mechanisms of those biases are still poorly understood because it is difficult to isolate the contributions of DNA repair from those of DNA damage. Results Here, we develop a genome-wide assay whereby the same DNA lesion is repaired in different genomic contexts. We insert thousands of barcoded transposons carrying a reporter of DNA mismatch repair in the genome of mouse embryonic stem cells. Upon inducing a double-strand break between tandem repeats, a mismatch is generated if the break is repaired through single-strand annealing. The resolution of the mismatch showed a 60–80% bias in favor of the strand with the longest 3′ flap. The location of the lesion in the genome and the type of mismatch had little influence on the bias. Instead, we observe a complete reversal of the bias when the longest 3′ flap is moved to the opposite strand by changing the position of the double-strand break in the reporter. Conclusions These results suggest that the processing of the double-strand break has a major influence on the repair of mismatches during a single-strand annealing. Supplementary Information The online version contains supplementary material available at 10.1186/s13059-022-02665-3.
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Affiliation(s)
- Victoria O Pokusaeva
- Center for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain.,Present Address: Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg, Austria
| | - Aránzazu Rosado Diez
- Center for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain.,Present Address: H12O-CNIO Lung Cancer Clinical Research Unit, i + 12 Research Institute, Spanish National Cancer Research Center (CNIO), Madrid, Spain
| | - Lorena Espinar
- Center for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Albert Torelló Pérez
- Center for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Guillaume J Filion
- Center for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain. .,University Pompeu Fabra (UPF), Barcelona, Spain. .,Present Address: Department Biological Sciences, University of Toronto Scarborough, Toronto, Canada.
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11
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Stark B, Poon GM, Wyrick JJ. Molecular mechanism of UV damage modulation in nucleosomes. Comput Struct Biotechnol J 2022; 20:5393-5400. [PMID: 36212527 PMCID: PMC9529667 DOI: 10.1016/j.csbj.2022.08.071] [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: 05/28/2022] [Revised: 08/31/2022] [Accepted: 08/31/2022] [Indexed: 12/02/2022] Open
Abstract
Exposure to ultraviolet (UV) light causes the formation of mutagenic cyclobutane pyrimidine dimers (CPDs) in cellular DNA. Previous studies have revealed that CPD formation in nucleosomes, the building blocks of chromatin, shows a striking ∼10 base pair (bp) periodic pattern. CPD formation is suppressed at positions where the DNA minor groove faces toward the histone octamer (minor-in) and elevated CPD formation at positions where the minor groove faces away from the histone octamer (minor-out). However, the molecular mechanism underlying this nucleosome photofootprint is unclear. Here, we analyzed ∼180 high-resolution nucleosome structures to characterize whether differences in DNA mobility or conformation are responsible for the CPD modulation in nucleosomes. Our results indicate that differences in DNA mobility cannot explain CPD modulation in nucleosome. Instead, we find that the sharp DNA bending around the histone octamer results in DNA conformations with structural parameters more susceptible to UV damage formation at minor-out positions and more resistant to CPD formation at minor-in positions. This analysis reveals the molecular mechanism responsible for periodic modulation of CPD formation and UV mutagenesis in nucleosomal DNA.
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12
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Seplyarskiy VB, Sunyaev S. The origin of human mutation in light of genomic data. Nat Rev Genet 2021; 22:672-686. [PMID: 34163020 DOI: 10.1038/s41576-021-00376-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2021] [Indexed: 02/05/2023]
Abstract
Despite years of active research into the role of DNA repair and replication in mutagenesis, surprisingly little is known about the origin of spontaneous human mutation in the germ line. With the advent of high-throughput sequencing, genome-scale data have revealed statistical properties of mutagenesis in humans. These properties include variation of the mutation rate and spectrum along the genome at different scales in relation to epigenomic features and dependency on parental age. Moreover, mutations originated in mothers are less frequent than mutations originated in fathers and have a distinct genomic distribution. Statistical analyses that interpret these patterns in the context of known biochemistry can provide mechanistic models of mutagenesis in humans.
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Affiliation(s)
- Vladimir B Seplyarskiy
- Division of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Shamil Sunyaev
- Division of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. .,Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA.
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13
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Morledge-Hampton B, Wyrick JJ. Mutperiod: Analysis of periodic mutation rates in nucleosomes. Comput Struct Biotechnol J 2021; 19:4177-4183. [PMID: 34527191 PMCID: PMC8349767 DOI: 10.1016/j.csbj.2021.07.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/21/2021] [Accepted: 07/23/2021] [Indexed: 11/19/2022] Open
Abstract
Nucleosomes modulate DNA damage and repair, resulting in periodic mutation rates in nucleosomal DNA. Previous research has characterized these patterns in many sequenced tumor genomes; however, computational tools to identify and quantify these periodicities have not been developed for the broader scientific community. Here, we describe mutperiod, a Python and R based toolset that quantifies nucleosome mutational periodicities and compares them across different genetic and cellular backgrounds. We use mutperiod to demonstrate that DNA mismatch repair contributes to the nucleosome mutational periodicity observed in esophageal adenocarcinomas, and that the strength of this mutational periodicity varies in different chromatin states.
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Affiliation(s)
- Benjamin Morledge-Hampton
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
- Corresponding authors at: School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA (B. Morledge-Hampton and J.J. Wyrick).
| | - John J. Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
- Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
- Corresponding authors at: School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA (B. Morledge-Hampton and J.J. Wyrick).
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14
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Barbier J, Vaillant C, Volff JN, Brunet FG, Audit B. Coupling between Sequence-Mediated Nucleosome Organization and Genome Evolution. Genes (Basel) 2021; 12:genes12060851. [PMID: 34205881 PMCID: PMC8228248 DOI: 10.3390/genes12060851] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 05/27/2021] [Accepted: 05/27/2021] [Indexed: 12/12/2022] Open
Abstract
The nucleosome is a major modulator of DNA accessibility to other cellular factors. Nucleosome positioning has a critical importance in regulating cell processes such as transcription, replication, recombination or DNA repair. The DNA sequence has an influence on the position of nucleosomes on genomes, although other factors are also implicated, such as ATP-dependent remodelers or competition of the nucleosome with DNA binding proteins. Different sequence motifs can promote or inhibit the nucleosome formation, thus influencing the accessibility to the DNA. Sequence-encoded nucleosome positioning having functional consequences on cell processes can then be selected or counter-selected during evolution. We review the interplay between sequence evolution and nucleosome positioning evolution. We first focus on the different ways to encode nucleosome positions in the DNA sequence, and to which extent these mechanisms are responsible of genome-wide nucleosome positioning in vivo. Then, we discuss the findings about selection of sequences for their nucleosomal properties. Finally, we illustrate how the nucleosome can directly influence sequence evolution through its interactions with DNA damage and repair mechanisms. This review aims to provide an overview of the mutual influence of sequence evolution and nucleosome positioning evolution, possibly leading to complex evolutionary dynamics.
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Affiliation(s)
- Jérémy Barbier
- Institut de Génomique Fonctionnelle de Lyon, Univ Lyon, CNRS UMR 5242, Ecole Normale Supérieure de Lyon, Univ Claude Bernard Lyon 1, F-69364 Lyon, France; (J.B.); (F.G.B.)
- Laboratoire de Physique, Univ Lyon, ENS de Lyon, CNRS, F-69342 Lyon, France;
| | - Cédric Vaillant
- Laboratoire de Physique, Univ Lyon, ENS de Lyon, CNRS, F-69342 Lyon, France;
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, Univ Lyon, CNRS UMR 5242, Ecole Normale Supérieure de Lyon, Univ Claude Bernard Lyon 1, F-69364 Lyon, France; (J.B.); (F.G.B.)
- Correspondence: (J.-N.V.); (B.A.)
| | - Frédéric G. Brunet
- Institut de Génomique Fonctionnelle de Lyon, Univ Lyon, CNRS UMR 5242, Ecole Normale Supérieure de Lyon, Univ Claude Bernard Lyon 1, F-69364 Lyon, France; (J.B.); (F.G.B.)
| | - Benjamin Audit
- Laboratoire de Physique, Univ Lyon, ENS de Lyon, CNRS, F-69342 Lyon, France;
- Correspondence: (J.-N.V.); (B.A.)
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15
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Bohm KA, Hodges AJ, Czaja W, Selvam K, Smerdon MJ, Mao P, Wyrick JJ. Distinct roles for RSC and SWI/SNF chromatin remodelers in genomic excision repair. Genome Res 2021; 31:1047-1059. [PMID: 34001524 PMCID: PMC8168587 DOI: 10.1101/gr.274373.120] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 04/19/2021] [Indexed: 12/30/2022]
Abstract
Nucleosomes are a significant barrier to the repair of UV damage because they impede damage recognition by nucleotide excision repair (NER). The RSC and SWI/SNF chromatin remodelers function in cells to promote DNA access by moving or evicting nucleosomes, and both have been linked to NER in yeast. Here, we report genome-wide repair maps of UV-induced cyclobutane pyrimidine dimers (CPDs) in yeast cells lacking RSC or SWI/SNF activity. Our data indicate that SWI/SNF is not generally required for NER but instead promotes repair of CPD lesions at specific yeast genes. In contrast, mutation or depletion of RSC subunits causes a general defect in NER across the yeast genome. Our data indicate that RSC is required for repair not only in nucleosomal DNA but also in neighboring linker DNA and nucleosome-free regions (NFRs). Although depletion of the RSC catalytic subunit also affects base excision repair (BER) of N-methylpurine (NMP) lesions, RSC activity is less important for BER in linker DNA and NFRs. Furthermore, our data indicate that RSC plays a direct role in transcription-coupled NER (TC-NER) of transcribed DNA. These findings help to define the specific genomic and chromatin contexts in which each chromatin remodeler functions in DNA repair, and indicate that RSC plays a unique function in facilitating repair by both NER subpathways.
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Affiliation(s)
- Kaitlynne A Bohm
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Amelia J Hodges
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Wioletta Czaja
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Kathiresan Selvam
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Michael J Smerdon
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Peng Mao
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - John J Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA.,Center for Reproductive Biology, Washington State University, Pullman, Washington 99164, USA
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16
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Yi SV, Goodisman MAD. The impact of epigenetic information on genome evolution. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200114. [PMID: 33866804 DOI: 10.1098/rstb.2020.0114] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Epigenetic information affects gene function by interacting with chromatin, while not changing the DNA sequence itself. However, it has become apparent that the interactions between epigenetic information and chromatin can, in fact, indirectly lead to DNA mutations and ultimately influence genome evolution. This review evaluates the ways in which epigenetic information affects genome sequence and evolution. We discuss how DNA methylation has strong and pervasive effects on DNA sequence evolution in eukaryotic organisms. We also review how the physical interactions arising from the connections between histone proteins and DNA affect DNA mutation and repair. We then discuss how a variety of epigenetic mechanisms exert substantial effects on genome evolution by suppressing the movement of transposable elements. Finally, we examine how genome expansion through gene duplication is also partially controlled by epigenetic information. Overall, we conclude that epigenetic information has widespread indirect effects on DNA sequences in eukaryotes and represents a potent cause and constraint of genome evolution. This article is part of the theme issue 'How does epigenetics influence the course of evolution?'
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Affiliation(s)
- Soojin V Yi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Michael A D Goodisman
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
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17
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A streamlined solution for processing, elucidating and quality control of cyclobutane pyrimidine dimer sequencing data. Nat Protoc 2021; 16:2190-2212. [PMID: 33731963 DOI: 10.1038/s41596-021-00496-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 01/06/2021] [Indexed: 01/13/2023]
Abstract
UV radiation may lead to melanoma and nonmelanoma skin cancers by causing helix-distorting DNA damage such as cyclobutane pyrimidine dimers (CPDs). These DNA lesions, if located in important genes and not repaired promptly, are mutagenic and may eventually result in carcinogenesis. Examining CPD formation and repair processes across the genome can shed light on the mutagenesis mechanisms associated with UV damage in relevant cancers. We recently developed CPD-Seq, a high-throughput and single-nucleotide resolution sequencing technique that can specifically capture UV-induced CPD lesions across the genome. This novel technique has been increasingly used in studies of UV damage and can be adapted to sequence other clinically relevant DNA lesions. Although the library preparation protocol has been established, a systematic protocol to analyze CPD-Seq data has not been described yet. To streamline the various general or specific analysis steps, we developed a protocol named CPDSeqer to assist researchers with CPD-Seq data processing. CPDSeqer can accommodate both a single- and multiple-sample experimental design, and it allows both genome-wide analyses and regional scrutiny (such as of suspected UV damage hotspots). The runtime of CPDSeqer scales with raw data size and takes roughly 4 h per sample with the possibility of acceleration by parallel computing. Various guiding graphics are generated to help diagnose the performance of the experiment and inform regional enrichment of CPD formation. UV damage comparison analyses are set forth in three analysis scenarios, and the resulting HTML pages report damage directional trends and statistical significance. CPDSeqer can be accessed at https://github.com/shengqh/cpdseqer .
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18
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Brambilla F, Garcia-Manteiga JM, Monteleone E, Hoelzen L, Zocchi A, Agresti A, Bianchi ME. Nucleosomes effectively shield DNA from radiation damage in living cells. Nucleic Acids Res 2020; 48:8993-9006. [PMID: 32710624 PMCID: PMC7498322 DOI: 10.1093/nar/gkaa613] [Citation(s) in RCA: 22] [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: 11/25/2019] [Revised: 06/22/2020] [Accepted: 07/10/2020] [Indexed: 12/16/2022] Open
Abstract
Eukaryotic DNA is organized in nucleosomes, which package DNA and regulate its accessibility to transcription, replication, recombination and repair. Here, we show that in living cells nucleosomes protect DNA from high-energy radiation and reactive oxygen species. We combined sequence-based methods (ATAC-seq and BLISS) to determine the position of both nucleosomes and double strand breaks (DSBs) in the genome of nucleosome-rich malignant mesothelioma cells, and of the same cells partially depleted of nucleosomes. The results were replicated in the human MCF-7 breast carcinoma cell line. We found that, for each genomic sequence, the probability of DSB formation is directly proportional to the fraction of time it is nucleosome-free; DSBs accumulate distal from the nucleosome dyad axis. Nucleosome free regions and promoters of actively transcribed genes are more sensitive to DSB formation, and consequently to mutation. We argue that this may be true for a variety of chemical and physical DNA damaging agents.
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Affiliation(s)
| | - Jose Manuel Garcia-Manteiga
- IRCCS San Raffaele Scientific Institute, via Olgettina 58, 20132 Milan, Italy
- Center for Omics Sciences, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Lena Hoelzen
- Università Vita-Salute San Raffaele, via Olgettina 58, 20132 Milan, Italy
- Faculty of Biology, Albert-Ludwigs-University Freiburg, D79104 Freiburg, Germany
| | - Angelica Zocchi
- Università Vita-Salute San Raffaele, via Olgettina 58, 20132 Milan, Italy
| | - Alessandra Agresti
- IRCCS San Raffaele Scientific Institute, via Olgettina 58, 20132 Milan, Italy
| | - Marco E Bianchi
- Università Vita-Salute San Raffaele, via Olgettina 58, 20132 Milan, Italy
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19
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Li W, Sancar A. Methodologies for detecting environmentally induced DNA damage and repair. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:664-679. [PMID: 32083352 PMCID: PMC7442611 DOI: 10.1002/em.22365] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 02/08/2020] [Accepted: 02/16/2020] [Indexed: 05/07/2023]
Abstract
Environmental DNA damaging agents continuously challenge the integrity of the genome by introducing a variety of DNA lesions. The DNA damage caused by environmental factors will lead to mutagenesis and subsequent carcinogenesis if they are not removed efficiently by repair pathways. Methods for detection of DNA damage and repair can be applied to identify, visualize, and quantify the DNA damage formation and repair events, and they enable us to illustrate the molecular mechanisms of DNA damage formation, DNA repair pathways, mutagenesis, and carcinogenesis. Ever since the discovery of the double helical structure of DNA in 1953, a great number of methods have been developed to detect various types of DNA damage and repair. Rapid advances in sequencing technologies have facilitated the emergence of a variety of novel methods for detecting environmentally induced DNA damage and repair at the genome-wide scale during the last decade. In this review, we provide a historical overview of the development of various damage detection methods. We also highlight the current methodologies to detect DNA damage and repair, especially some next generation sequencing-based methods.
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Affiliation(s)
- Wentao Li
- Correspondence to: Wentao Li and Aziz Sancar, Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599. and
| | - Aziz Sancar
- Correspondence to: Wentao Li and Aziz Sancar, Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599. and
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20
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Gsell C, Richly H, Coin F, Naegeli H. A chromatin scaffold for DNA damage recognition: how histone methyltransferases prime nucleosomes for repair of ultraviolet light-induced lesions. Nucleic Acids Res 2020; 48:1652-1668. [PMID: 31930303 PMCID: PMC7038933 DOI: 10.1093/nar/gkz1229] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/18/2019] [Accepted: 12/23/2019] [Indexed: 02/07/2023] Open
Abstract
The excision of mutagenic DNA adducts by the nucleotide excision repair (NER) pathway is essential for genome stability, which is key to avoiding genetic diseases, premature aging, cancer and neurologic disorders. Due to the need to process an extraordinarily high damage density embedded in the nucleosome landscape of chromatin, NER activity provides a unique functional caliper to understand how histone modifiers modulate DNA damage responses. At least three distinct lysine methyltransferases (KMTs) targeting histones have been shown to facilitate the detection of ultraviolet (UV) light-induced DNA lesions in the difficult to access DNA wrapped around histones in nucleosomes. By methylating core histones, these KMTs generate docking sites for DNA damage recognition factors before the chromatin structure is ultimately relaxed and the offending lesions are effectively excised. In view of their function in priming nucleosomes for DNA repair, mutations of genes coding for these KMTs are expected to cause the accumulation of DNA damage promoting cancer and other chronic diseases. Research on the question of how KMTs modulate DNA repair might pave the way to the development of pharmacologic agents for novel therapeutic strategies.
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Affiliation(s)
- Corina Gsell
- Institute of Pharmacology and Toxicology, University of Zurich-Vetsuisse, Winterthurerstrasse 260, 8057 Zurich, Switzerland
| | - Holger Richly
- Boehringer Ingelheim Pharma, Department of Molecular Biology, Birkendorfer Str. 65, 88397 Biberach an der Riß, Germany
| | - Frédéric Coin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Equipe Labélisée Ligue contre le Cancer, Illkirch Cedex, Strasbourg, France
| | - Hanspeter Naegeli
- Institute of Pharmacology and Toxicology, University of Zurich-Vetsuisse, Winterthurerstrasse 260, 8057 Zurich, Switzerland
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21
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Abstract
Ultraviolet (UV) irradiation causes various types of DNA damage, which leads to specific mutations and the emergence of skin cancer in humans, often decades after initial exposure. Different UV wavelengths cause the formation of prominent UV-induced DNA lesions. Most of these lesions are removed by the nucleotide excision repair pathway, which is defective in rare genetic skin disorders referred to as xeroderma pigmentosum. A major role in inducing sunlight-dependent skin cancer mutations is assigned to the cyclobutane pyrimidine dimers (CPDs). In this review, we discuss the mechanisms of UV damage induction, the genomic distribution of this damage, relevant DNA repair mechanisms, the proposed mechanisms of how UV-induced CPDs bring about DNA replication-dependent mutagenicity in mammalian cells, and the strong signature of UV damage and mutagenesis found in skin cancer genomes.
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22
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Gonzalez-Perez A, Sabarinathan R, Lopez-Bigas N. Local Determinants of the Mutational Landscape of the Human Genome. Cell 2020; 177:101-114. [PMID: 30901533 DOI: 10.1016/j.cell.2019.02.051] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 02/13/2019] [Accepted: 02/26/2019] [Indexed: 12/19/2022]
Abstract
Large-scale chromatin features, such as replication time and accessibility influence the rate of somatic and germline mutations at the megabase scale. This article reviews how local chromatin structures -e.g., DNA wrapped around nucleosomes, transcription factors bound to DNA- affect the mutation rate at a local scale. It dissects how the interaction of some mutagenic agents and/or DNA repair systems with these local structures influence the generation of mutations. We discuss how this local mutation rate variability affects our understanding of the evolution of the genomic sequence, and the study of the evolution of organisms and tumors.
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Affiliation(s)
- Abel Gonzalez-Perez
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain; Research Program on Biomedical Informatics, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain.
| | - Radhakrishnan Sabarinathan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India.
| | - Nuria Lopez-Bigas
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain; Research Program on Biomedical Informatics, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
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23
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Fang H, Barbour JA, Poulos RC, Katainen R, Aaltonen LA, Wong JWH. Mutational processes of distinct POLE exonuclease domain mutants drive an enrichment of a specific TP53 mutation in colorectal cancer. PLoS Genet 2020; 16:e1008572. [PMID: 32012149 PMCID: PMC7018097 DOI: 10.1371/journal.pgen.1008572] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 02/13/2020] [Accepted: 12/17/2019] [Indexed: 01/16/2023] Open
Abstract
Cancer genomes with mutations in the exonuclease domain of Polymerase Epsilon (POLE) present with an extraordinarily high somatic mutation burden. In vitro studies have shown that distinct POLE mutants exhibit different polymerase activity. Yet, genome-wide mutation patterns and driver mutation formation arising from different POLE mutants remains unclear. Here, we curated somatic mutation calls from 7,345 colorectal cancer samples from published studies and publicly available databases. These include 44 POLE mutant samples including 9 with whole genome sequencing data available. The POLE mutant samples were categorized based on the specific POLE mutation present. Mutation spectrum, associations of somatic mutations with epigenomics features and co-occurrence with specific driver mutations were examined across different POLE mutants. We found that different POLE mutants exhibit distinct mutation spectrum with significantly higher relative frequency of C>T mutations in POLE V411L mutants. Our analysis showed that this increase frequency in C>T mutations is not dependent on DNA methylation and not associated with other genomic features and is thus specifically due to DNA sequence context alone. Notably, we found strong association of the TP53 R213* mutation specifically with POLE P286R mutants. This truncation mutation occurs within the TT[C>T]GA context. For C>T mutations, this sequence context is significantly more likely to be mutated in POLE P286R mutants compared with other POLE exonuclease domain mutants. This study refines our understanding of DNA polymerase fidelity and underscores genome-wide mutation spectrum and specific cancer driver mutation formation observed in POLE mutant cancers. Cancer arises through the accumulation of somatic mutations. The way that these somatic mutations form can vary greatly in different cancers. One of the most mutagenic processes that have been identified is caused by mutations within a replicative DNA polymerase known as Polymerase Epsilon (POLE). Cancers with such mutations present with hundreds of thousands of somatic mutations in their genome. Previous cancer genomics studies have identified a number of mutation hotspots in POLE, however how these different POLE mutants behave in affecting mutation distribution has not been studied. Here, we describe the genome-wide mutation profiles of distinct POLE mutant cancers. We find that different mutants indeed result in different mutation profiles and that this can be explained by the different fidelities of these mutants in replicating specific DNA sequences. Significantly, these differences have important implications in cancer formation as we found that a POLE mutation is strongly associated with a specific truncation of the TP53 cancer driver gene. This study furthers our understanding of the POLE mutagenic process in cancer and provide important insights into carcinogenesis in cancers with such mutations.
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Affiliation(s)
- Hu Fang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region
| | - Jayne A. Barbour
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region
- Prince of Wales Clinical School, UNSW Medicine, UNSW Sydney, New South Wales, Australia
| | - Rebecca C. Poulos
- Children’s Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead, New South Wales, Australia
| | - Riku Katainen
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Lauri A. Aaltonen
- Applied Tumor Genomics Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Jason W. H. Wong
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region
- Prince of Wales Clinical School, UNSW Medicine, UNSW Sydney, New South Wales, Australia
- * E-mail:
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24
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Abstract
Exposure to ultraviolet (UV) radiation is the major risk factor for skin cancers. UV induces helix-distorting DNA damage such as cyclobutane pyrimidine dimers (CPDs). If not repaired, CPDs can strongly block DNA and RNA polymerases and cause mutagenesis or cell death. Nucleotide excision repair (NER) is critical for the removal of UV-induced photolesions including CPDs in the cell. Investigating CPD formation and repair across the genome is important for understanding the mechanisms by which these lesions promote somatic mutations in skin cancers. Here we describe a high-throughput, single nucleotide-resolution damage mapping method named CPD sequencing (CPD-seq) for genome-wide analysis of UV-induced CPDs. Protocols for CPD-seq library preparation in yeast and human cells, as well as bioinformatics identification of the CPD damage site, are detailed below.
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Affiliation(s)
- Peng Mao
- School of Molecular Biosciences, Washington State University, Pullman, WA, USA
| | - John J Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA, USA.
- Center for Reproductive Biology, Washington State University, Pullman, WA, USA.
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25
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Mao P, Smerdon MJ, Roberts SA, Wyrick JJ. Asymmetric repair of UV damage in nucleosomes imposes a DNA strand polarity on somatic mutations in skin cancer. Genome Res 2019; 30:12-21. [PMID: 31871068 PMCID: PMC6961582 DOI: 10.1101/gr.253146.119] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 12/06/2019] [Indexed: 12/20/2022]
Abstract
Nucleosomes inhibit excision repair of DNA damage caused by ultraviolet (UV) light, and it has been generally assumed that repair inhibition is equivalent on both sides of the nucleosome dyad. Here, we use genome-wide repair data to show that repair of UV damage in nucleosomes is asymmetric. In yeast, nucleosomes inhibit nucleotide excision repair (NER) of the nontranscribed strand (NTS) of genes in an asymmetric manner, with faster repair of UV damage occurring on the 5′ side of the nucleosomal DNA. Analysis of genomic repair data from UV-irradiated human cells indicates that NER activity along the NTS is also elevated on the 5′ side of nucleosomes, consistent with the repair asymmetry observed in yeast nucleosomes. Among intergenic nucleosomes, repair activity is elevated on the 5′ side of both DNA strands. The distribution of somatic mutations in nucleosomes shows the opposite asymmetry in NER-proficient skin cancers, but not in NER-deficient cancers, indicating that asymmetric repair of nucleosomal DNA imposes a strand polarity on UV mutagenesis. Somatic mutations are enriched on the relatively slow-repairing 3′ side of the nucleosomal DNA, particularly at positions where the DNA minor groove faces away from the histone octamer. Asymmetric repair and mutagenesis are likely caused by differential accessibility of the nucleosomal DNA, a consequence of its left-handed wrapping around the histone octamer.
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Affiliation(s)
- Peng Mao
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Michael J Smerdon
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA
| | - Steven A Roberts
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA.,Center for Reproductive Biology, Washington State University, Pullman, Washington 99164, USA
| | - John J Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, USA.,Center for Reproductive Biology, Washington State University, Pullman, Washington 99164, USA
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26
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Mao P, Wyrick JJ. Organization of DNA damage, excision repair, and mutagenesis in chromatin: A genomic perspective. DNA Repair (Amst) 2019; 81:102645. [PMID: 31307926 DOI: 10.1016/j.dnarep.2019.102645] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Genomic DNA is constantly assaulted by both endogenous and exogenous damaging agents. The resulting DNA damage, if left unrepaired, can interfere with DNA replication and be converted into mutations. Genomic DNA is packaged into a highly compact yet dynamic chromatin structure, in order to fit into the limited space available in the nucleus of eukaryotic cells. This hierarchical chromatin organization serves as both the target of DNA damaging agents and the context for DNA repair enzymes. Biochemical studies have suggested that both the formation and repair of DNA damage are significantly modulated by chromatin. Our understanding of the impact of chromatin on damage and repair has been significantly enhanced by recent studies. We focus on the nucleosome, the primary building block of chromatin, and discuss how the intrinsic structural properties of nucleosomes, and their associated epigenetic modifications, affect damage formation and DNA repair, as well as subsequent mutagenesis in cancer.
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Affiliation(s)
- Peng Mao
- School of Molecular Biosciences, Washington State University, Pullman, WA, 99164, USA
| | - John J Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA, 99164, USA; Center for Reproductive Biology, Washington State University, Pullman, WA, 99164, USA.
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27
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Supek F, Lehner B. Scales and mechanisms of somatic mutation rate variation across the human genome. DNA Repair (Amst) 2019; 81:102647. [PMID: 31307927 DOI: 10.1016/j.dnarep.2019.102647] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cancer genome sequencing has revealed that somatic mutation rates vary substantially across the human genome and at scales from megabase-sized domains to individual nucleotides. Here we review recent work that has both revealed the major mutation biases that operate across the genome and the molecular mechanisms that cause them. The default mutation rate landscape in mammalian genomes results in active genes having low mutation rates because of a combination of factors that increase DNA repair: early DNA replication, transcription, active chromatin modifications and accessible chromatin. Therefore, either an increase in the global mutation rate or a redistribution of mutations from inactive to active DNA can increase the rate at which consequential mutations are acquired in active genes. Several environmental carcinogens and intrinsic mechanisms operating in tumor cells likely cause cancer by this second mechanism: by specifically increasing the mutation rate in active regions of the genome.
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Affiliation(s)
- Fran Supek
- Genome Data Science, Institut de Recerca Biomedica (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028, Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain.
| | - Ben Lehner
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain; Systems Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Doctor Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
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28
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DNA damage detection in nucleosomes involves DNA register shifting. Nature 2019; 571:79-84. [PMID: 31142837 PMCID: PMC6611726 DOI: 10.1038/s41586-019-1259-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 05/01/2019] [Indexed: 02/07/2023]
Abstract
Access to DNA packaged in nucleosomes is critical for gene regulation, DNA replication and repair. In humans, the UV-DDB complex detects ultraviolet light induced pyrimidine dimers throughout the genome, yet it remains unknown how these lesions are recognised in chromatin, where nucleosomes restrict DNA access. Here we report cryo-electron microscopy structures for UV-DDB bound to nucleosomes bearing a 6-4 pyrimidine-pyrimidone dimer, and a DNA damage mimic at a variety of positions. We find that UV-DDB binds UV damaged nucleosomes at lesions located in the solvent-facing minor groove without affecting the overall nucleosome architecture. For buried lesions facing the histone core, UV-DDB changes the predominant translational register of the nucleosome, and selectively binds the lesion in an accessible, exposed, position. These findings explain how UV-DDB detects occluded lesions in strongly positioned nucleosomes. We identify slide-assisted site-exposure (SAsSE) as a mechanism for high-affinity DNA-binding proteins to access otherwise occluded sites in nucleosomal DNA.
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29
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Roberts SA, Brown AJ, Wyrick JJ. Recurrent Noncoding Mutations in Skin Cancers: UV Damage Susceptibility or Repair Inhibition as Primary Driver? Bioessays 2019; 41:e1800152. [PMID: 30801747 PMCID: PMC6571124 DOI: 10.1002/bies.201800152] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 12/05/2018] [Indexed: 12/14/2022]
Abstract
Somatic mutations arising in human skin cancers are heterogeneously distributed across the genome, meaning that certain genomic regions (e.g., heterochromatin or transcription factor binding sites) have much higher mutation densities than others. Regional variations in mutation rates are typically not a consequence of selection, as the vast majority of somatic mutations in skin cancers are passenger mutations that do not promote cell growth or transformation. Instead, variations in DNA repair activity, due to chromatin organization and transcription factor binding, have been proposed to be a primary driver of mutational heterogeneity in melanoma. However, as discussed in this review here, recent studies indicate that chromatin organization and transcription factor binding also significantly modulate the rate at which UV lesions form in DNA. The authors propose that local variations in lesion susceptibility may be an important driver of mutational hotspots in melanoma and other skin cancers, particularly at binding sites for ETS transcription factors.
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Affiliation(s)
- Steven A. Roberts
- School of Molecular Biosciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164
| | - Alexander J. Brown
- School of Molecular Biosciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164
| | - John J. Wyrick
- School of Molecular Biosciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164
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