1
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Rückert T, Romagnani C. Extrinsic and intrinsic drivers of natural killer cell clonality. Immunol Rev 2024; 323:80-106. [PMID: 38506411 DOI: 10.1111/imr.13324] [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: 03/21/2024]
Abstract
Clonal expansion of antigen-specific lymphocytes is the fundamental mechanism enabling potent adaptive immune responses and the generation of immune memory. Accompanied by pronounced epigenetic remodeling, the massive proliferation of individual cells generates a critical mass of effectors for the control of acute infections, as well as a pool of memory cells protecting against future pathogen encounters. Classically associated with the adaptive immune system, recent work has demonstrated that innate immune memory to human cytomegalovirus (CMV) infection is stably maintained as large clonal expansions of natural killer (NK) cells, raising questions on the mechanisms for clonal selection and expansion in the absence of re-arranged antigen receptors. Here, we discuss clonal NK cell memory in the context of the mechanisms underlying clonal competition of adaptive lymphocytes and propose alternative selection mechanisms that might decide on the clonal success of their innate counterparts. We propose that the integration of external cues with cell-intrinsic sources of heterogeneity, such as variegated receptor expression, transcriptional states, and somatic variants, compose a bottleneck for clonal selection, contributing to the large size of memory NK cell clones.
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Affiliation(s)
- Timo Rückert
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Immunology, Berlin, Germany
| | - Chiara Romagnani
- Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Immunology, Berlin, Germany
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2
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Ngo TTM, Liu B, Wang F, Basu A, Wu C, Ha T. Dependence of nucleosome mechanical stability on DNA mismatches. eLife 2024; 13:RP95514. [PMID: 38656237 DOI: 10.7554/elife.95514] [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: 04/26/2024] Open
Abstract
The organization of nucleosomes into chromatin and their accessibility are shaped by local DNA mechanics. Conversely, nucleosome positions shape genetic variations, which may originate from mismatches during replication and chemical modification of DNA. To investigate how DNA mismatches affect the mechanical stability and the exposure of nucleosomal DNA, we used an optical trap combined with single-molecule FRET and a single-molecule FRET cyclization assay. We found that a single base-pair C-C mismatch enhances DNA bendability and nucleosome mechanical stability for the 601-nucleosome positioning sequence. An increase in force required for DNA unwrapping from the histone core is observed for single base-pair C-C mismatches placed at three tested positions: at the inner turn, at the outer turn, or at the junction of the inner and outer turn of the nucleosome. The results support a model where nucleosomal DNA accessibility is reduced by mismatches, potentially explaining the preferred accumulation of single-nucleotide substitutions in the nucleosome core and serving as the source of genetic variation during evolution and cancer progression. Mechanical stability of an intact nucleosome, that is mismatch-free, is also dependent on the species as we find that yeast nucleosomes are mechanically less stable and more symmetrical in the outer turn unwrapping compared to Xenopus nucleosomes.
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Affiliation(s)
- Thuy T M Ngo
- Department of Physics, Center for Physics in Living Cells University of Illinois Urbana-Champaign, Urbana, United States
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, United States
- Cancer Early Detection Advanced Research Center (CEDAR), Knight Cancer Institute, Oregon Health and Science University, Portland, United States
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, United States
- Division of Oncological Sciences, Oregon Health and Science University, Portland, United States
| | - Bailey Liu
- Department of Biophysics, Johns Hopkins University, Baltimore, United States
| | - Feng Wang
- Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, United States
| | - Aakash Basu
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, United States
- Department of Biosciences, Durham University, Durham, United Kingdom
| | - Carl Wu
- Department of Biology, Johns Hopkins University, Baltimore, United States
- Department of Molecular Biology and Genetics, Johns Hopkins University, Baltimore, United States
| | - Taekjip Ha
- Department of Physics, Center for Physics in Living Cells University of Illinois Urbana-Champaign, Urbana, United States
- Department of Biophysics, Johns Hopkins University, Baltimore, United States
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, United States
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, United States
- Department of Pediatrics, Harvard Medical School, Boston, United States
- Howard Hughes Medical Institute, Boston, United States
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3
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Webster AK, Phillips PC. Heritable epigenetic variation facilitates long-term maintenance of epigenetic and genetic variation. G3 (BETHESDA, MD.) 2024; 14:jkad287. [PMID: 38113034 PMCID: PMC10849368 DOI: 10.1093/g3journal/jkad287] [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: 08/03/2023] [Revised: 08/03/2023] [Accepted: 11/22/2023] [Indexed: 12/21/2023]
Abstract
How genetic and phenotypic variation are maintained has long been one of the fundamental questions in population and quantitative genetics. A variety of factors have been implicated to explain the maintenance of genetic variation in some contexts (e.g. balancing selection), but the potential role of epigenetic regulation to influence population dynamics has been understudied. It is well recognized that epigenetic regulation, including histone methylation, small RNA expression, and DNA methylation, helps to define differences between cell types and facilitate phenotypic plasticity. In recent years, empirical studies have shown the potential for epigenetic regulation to also be heritable for at least a few generations without selection, raising the possibility that differences in epigenetic regulation can act alongside genetic variation to shape evolutionary trajectories. Heritable differences in epigenetic regulation that arise spontaneously are termed "epimutations." Epimutations differ from genetic mutations in 2 key ways-they occur at a higher rate and the loci at which they occur often revert back to their original state within a few generations. Here, we present an extension of the standard population genetic model with selection to incorporate epigenetic variation arising via epimutation. Our model assumes a diploid, sexually reproducing population with random mating. In addition to spontaneous genetic mutation, we included parameters for spontaneous epimutation and back-epimutation, allowing for 4 potential epialleles at a single locus (2 genetic alleles, each with 2 epigenetic states), each of which affect fitness. We then analyzed the conditions under which stable epialleles were maintained. Our results show that highly reversible epialleles can be maintained in long-term equilibrium under neutral conditions in a manner that depends on the epimutation and back-epimutation rates, which we term epimutation-back-epimutation equilibrium. On the other hand, epialleles that compensate for deleterious mutations cause deviations from the expectations of mutation-selection balance by a simple factor that depends on the epimutation and back-epimutation rates. We also numerically analyze several sets of fitness parameters for which large deviations from mutation-selection balance occur. Together, these results demonstrate that transient epigenetic regulation may be an important factor in the maintenance of both epigenetic and genetic variation in populations.
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Affiliation(s)
- Amy K Webster
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA
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4
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Lynch M, Ali F, Lin T, Wang Y, Ni J, Long H. The divergence of mutation rates and spectra across the Tree of Life. EMBO Rep 2023; 24:e57561. [PMID: 37615267 PMCID: PMC10561183 DOI: 10.15252/embr.202357561] [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: 05/29/2023] [Revised: 08/01/2023] [Accepted: 08/02/2023] [Indexed: 08/25/2023] Open
Abstract
Owing to advances in genome sequencing, genome stability has become one of the most scrutinized cellular traits across the Tree of Life. Despite its centrality to all things biological, the mutation rate (per nucleotide site per generation) ranges over three orders of magnitude among species and several-fold within individual phylogenetic lineages. Within all major organismal groups, mutation rates scale negatively with the effective population size of a species and with the amount of functional DNA in the genome. This relationship is most parsimoniously explained by the drift-barrier hypothesis, which postulates that natural selection typically operates to reduce mutation rates until further improvement is thwarted by the power of random genetic drift. Despite this constraint, the molecular mechanisms underlying DNA replication fidelity and repair are free to wander, provided the performance of the entire system is maintained at the prevailing level. The evolutionary flexibility of the mutation rate bears on the resolution of several prior conundrums in phylogenetic and population-genetic analysis and raises challenges for future applications in these areas.
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Affiliation(s)
- Michael Lynch
- Biodesign Center for Mechanisms of EvolutionArizona State UniversityTempeAZUSA
| | - Farhan Ali
- Biodesign Center for Mechanisms of EvolutionArizona State UniversityTempeAZUSA
| | - Tongtong Lin
- Institute of Evolution and Marine Biodiversity, KLMMEOcean University of ChinaQingdaoChina
| | - Yaohai Wang
- Institute of Evolution and Marine Biodiversity, KLMMEOcean University of ChinaQingdaoChina
| | - Jiahao Ni
- Institute of Evolution and Marine Biodiversity, KLMMEOcean University of ChinaQingdaoChina
| | - Hongan Long
- Institute of Evolution and Marine Biodiversity, KLMMEOcean University of ChinaQingdaoChina
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5
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Staunton PM, Peters AJ, Seoighe C. Somatic mutations inferred from RNA-seq data highlight the contribution of replication timing to mutation rate variation in a model plant. Genetics 2023; 225:iyad128. [PMID: 37450609 PMCID: PMC10550316 DOI: 10.1093/genetics/iyad128] [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: 03/23/2023] [Revised: 03/23/2023] [Accepted: 06/11/2023] [Indexed: 07/18/2023] Open
Abstract
Variation in the rates and characteristics of germline and somatic mutations across the genome of an organism is informative about DNA damage and repair processes and can also shed light on aspects of organism physiology and evolution. We adapted a recently developed method for inferring somatic mutations from bulk RNA-seq data and applied it to a large collection of Arabidopsis thaliana accessions. The wide range of genomic data types available for A. thaliana enabled us to investigate the relationships of multiple genomic features with the variation in the somatic mutation rate across the genome of this model plant. We observed that late replicated regions showed evidence of an elevated rate of somatic mutation compared to genomic regions that are replicated early. We identified transcriptional strand asymmetries, consistent with the effects of transcription-coupled damage and/or repair. We also observed a negative relationship between the inferred somatic mutation count and the H3K36me3 histone mark which is well documented in the literature of human systems. In addition, we were able to support previous reports of an inverse relationship between inferred somatic mutation count and guanine-cytosine content as well as a positive relationship between inferred somatic mutation count and DNA methylation for both cytosine and noncytosine mutations.
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Affiliation(s)
- Patrick M Staunton
- School of Mathematical and Statistical Sciences, University of Galway, Galway H91 TK33, Ireland
| | - Andrew J Peters
- School of Mathematical and Statistical Sciences, University of Galway, Galway H91 TK33, Ireland
| | - Cathal Seoighe
- School of Mathematical and Statistical Sciences, University of Galway, Galway H91 TK33, Ireland
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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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Williams JD, Zhu D, García-Rubio M, Shaltz S, Aguilera A, Jinks-Robertson S. Spontaneous deamination of cytosine to uracil is biased to the non-transcribed DNA strand in yeast. DNA Repair (Amst) 2023; 126:103489. [PMID: 37018983 PMCID: PMC10494324 DOI: 10.1016/j.dnarep.2023.103489] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 03/19/2023] [Accepted: 03/28/2023] [Indexed: 03/31/2023]
Abstract
Transcription in Saccharomyces cerevisiae is associated with elevated mutation and this partially reflects enhanced damage of the corresponding DNA. Spontaneous deamination of cytosine to uracil leads to CG>TA mutations that provide a strand-specific read-out of damage in strains that lack the ability to remove uracil from DNA. Using the CAN1 forward mutation reporter, we found that C>T and G>A mutations, which reflect deamination of the non-transcribed and transcribed DNA strands, respectively, occurred at similar rates under low-transcription conditions. By contrast, the rate of C>T mutations was 3-fold higher than G>A mutations under high-transcription conditions, demonstrating biased deamination of the non-transcribed strand (NTS). The NTS is transiently single-stranded within the ∼15 bp transcription bubble, or a more extensive region of the NTS can be exposed as part of an R-loop that can form behind RNA polymerase. Neither the deletion of genes whose products restrain R-loop formation nor the over-expression of RNase H1, which degrades R-loops, reduced the biased deamination of the NTS, and no transcription-associated R-loop formation at CAN1 was detected. These results suggest that the NTS within the transcription bubble is a target for spontaneous deamination and likely other types of DNA damage.
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Affiliation(s)
- Jonathan D Williams
- Department of Molecular Genetics and Microbiology, 213 Research Dr., Duke University Medical Center, Durham, NC 27710, USA
| | - Demi Zhu
- Department of Molecular Genetics and Microbiology, 213 Research Dr., Duke University Medical Center, Durham, NC 27710, USA
| | - María García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC, Seville, Spain
| | - Samantha Shaltz
- Department of Molecular Genetics and Microbiology, 213 Research Dr., Duke University Medical Center, Durham, NC 27710, USA
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC, Seville, Spain
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, 213 Research Dr., Duke University Medical Center, Durham, NC 27710, USA.
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8
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Palazzo AF, Kejiou NS. Non-Darwinian Molecular Biology. Front Genet 2022; 13:831068. [PMID: 35251134 PMCID: PMC8888898 DOI: 10.3389/fgene.2022.831068] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/24/2022] [Indexed: 12/14/2022] Open
Abstract
With the discovery of the double helical structure of DNA, a shift occurred in how biologists investigated questions surrounding cellular processes, such as protein synthesis. Instead of viewing biological activity through the lens of chemical reactions, this new field used biological information to gain a new profound view of how biological systems work. Molecular biologists asked new types of questions that would have been inconceivable to the older generation of researchers, such as how cellular machineries convert inherited biological information into functional molecules like proteins. This new focus on biological information also gave molecular biologists a way to link their findings to concepts developed by genetics and the modern synthesis. However, by the late 1960s this all changed. Elevated rates of mutation, unsustainable genetic loads, and high levels of variation in populations, challenged Darwinian evolution, a central tenant of the modern synthesis, where adaptation was the main driver of evolutionary change. Building on these findings, Motoo Kimura advanced the neutral theory of molecular evolution, which advocates that selection in multicellular eukaryotes is weak and that most genomic changes are neutral and due to random drift. This was further elaborated by Jack King and Thomas Jukes, in their paper “Non-Darwinian Evolution”, where they pointed out that the observed changes seen in proteins and the types of polymorphisms observed in populations only become understandable when we take into account biochemistry and Kimura’s new theory. Fifty years later, most molecular biologists remain unaware of these fundamental advances. Their adaptionist viewpoint fails to explain data collected from new powerful technologies which can detect exceedingly rare biochemical events. For example, high throughput sequencing routinely detects RNA transcripts being produced from almost the entire genome yet are present less than one copy per thousand cells and appear to lack any function. Molecular biologists must now reincorporate ideas from classical biochemistry and absorb modern concepts from molecular evolution, to craft a new lens through which they can evaluate the functionality of transcriptional units, and make sense of our messy, intricate, and complicated genome.
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9
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Monroe JG, Srikant T, Carbonell-Bejerano P, Becker C, Lensink M, Exposito-Alonso M, Klein M, Hildebrandt J, Neumann M, Kliebenstein D, Weng ML, Imbert E, Ågren J, Rutter MT, Fenster CB, Weigel D. Mutation bias reflects natural selection in Arabidopsis thaliana. Nature 2022; 602:101-105. [PMID: 35022609 PMCID: PMC8810380 DOI: 10.1038/s41586-021-04269-6] [Citation(s) in RCA: 152] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 11/17/2021] [Indexed: 12/24/2022]
Abstract
Since the first half of the twentieth century, evolutionary theory has been dominated by the idea that mutations occur randomly with respect to their consequences1. Here we test this assumption with large surveys of de novo mutations in the plant Arabidopsis thaliana. In contrast to expectations, we find that mutations occur less often in functionally constrained regions of the genome-mutation frequency is reduced by half inside gene bodies and by two-thirds in essential genes. With independent genomic mutation datasets, including from the largest Arabidopsis mutation accumulation experiment conducted to date, we demonstrate that epigenomic and physical features explain over 90% of variance in the genome-wide pattern of mutation bias surrounding genes. Observed mutation frequencies around genes in turn accurately predict patterns of genetic polymorphisms in natural Arabidopsis accessions (r = 0.96). That mutation bias is the primary force behind patterns of sequence evolution around genes in natural accessions is supported by analyses of allele frequencies. Finally, we find that genes subject to stronger purifying selection have a lower mutation rate. We conclude that epigenome-associated mutation bias2 reduces the occurrence of deleterious mutations in Arabidopsis, challenging the prevailing paradigm that mutation is a directionless force in evolution.
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Affiliation(s)
- J Grey Monroe
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen, Germany.
- Department of Plant Sciences, University of California Davis, Davis, CA, USA.
| | - Thanvi Srikant
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | | | - Claude Becker
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen, Germany
- Faculty of Biology, Ludwig Maximilian University, Martinsried, Germany
| | - Mariele Lensink
- Department of Plant Sciences, University of California Davis, Davis, CA, USA
| | - Moises Exposito-Alonso
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, USA
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Marie Klein
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen, Germany
- Department of Plant Sciences, University of California Davis, Davis, CA, USA
| | - Julia Hildebrandt
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Manuela Neumann
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen, Germany
| | - Daniel Kliebenstein
- Department of Plant Sciences, University of California Davis, Davis, CA, USA
| | - Mao-Lun Weng
- Department of Biology, Westfield State University, Westfield, MA, USA
| | - Eric Imbert
- ISEM, University of Montpellier, Montpellier, France
| | - Jon Ågren
- Department of Ecology and Genetics, EBC, Uppsala University, Uppsala, Sweden
| | - Matthew T Rutter
- Department of Biology, College of Charleston, Charleston, SC, USA
| | - Charles B Fenster
- Oak Lake Field Station, South Dakota State University, Brookings, SD, USA
| | - Detlef Weigel
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, Tübingen, Germany.
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10
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Deng S, Xing K, He X. Mutation signatures inform the natural host of SARS-CoV-2. Natl Sci Rev 2021; 9:nwab220. [PMID: 35211321 PMCID: PMC8690307 DOI: 10.1093/nsr/nwab220] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/18/2021] [Accepted: 12/01/2021] [Indexed: 11/25/2022] Open
Affiliation(s)
- Shanjun Deng
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou510275, China
| | - Ke Xing
- School of Life Sciences, Guangzhou University, Guangzhou511442, China
| | - Xionglei He
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou510275, China
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11
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Mapping single-cell-resolution cell phylogeny reveals cell population dynamics during organ development. Nat Methods 2021; 18:1506-1514. [PMID: 34857936 DOI: 10.1038/s41592-021-01325-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 10/18/2021] [Indexed: 12/20/2022]
Abstract
Mapping the cell phylogeny of a complex multicellular organism relies on somatic mutations accumulated from zygote to adult. Available cell barcoding methods can record about three mutations per barcode, enabling only low-resolution mapping of the cell phylogeny of complex organisms. Here we developed SMALT, a substitution mutation-aided lineage-tracing system that outperforms the available cell barcoding methods in mapping cell phylogeny. We applied SMALT to Drosophila melanogaster and obtained on average more than 20 mutations on a three-kilobase-pair barcoding sequence in early-adult cells. Using the barcoding mutations, we obtained high-quality cell phylogenetic trees, each comprising several thousand internal nodes with 84-93% median bootstrap support. The obtained cell phylogenies enabled a population genetic analysis that estimates the longitudinal dynamics of the number of actively dividing parental cells (Np) in each organ through development. The Np dynamics revealed the trajectory of cell births and provided insight into the balance of symmetric and asymmetric cell division.
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12
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Epigenetic modifications affect the rate of spontaneous mutations in a pathogenic fungus. Nat Commun 2021; 12:5869. [PMID: 34620872 PMCID: PMC8497519 DOI: 10.1038/s41467-021-26108-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 09/17/2021] [Indexed: 12/17/2022] Open
Abstract
Mutations are the source of genetic variation and the substrate for evolution. Genome-wide mutation rates appear to be affected by selection and are probably adaptive. Mutation rates are also known to vary along genomes, possibly in response to epigenetic modifications, but causality is only assumed. In this study we determine the direct impact of epigenetic modifications and temperature stress on mitotic mutation rates in a fungal pathogen using a mutation accumulation approach. Deletion mutants lacking epigenetic modifications confirm that histone mark H3K27me3 increases whereas H3K9me3 decreases the mutation rate. Furthermore, cytosine methylation in transposable elements (TE) increases the mutation rate 15-fold resulting in significantly less TE mobilization. Also accessory chromosomes have significantly higher mutation rates. Finally, we find that temperature stress substantially elevates the mutation rate. Taken together, we find that epigenetic modifications and environmental conditions modify the rate and the location of spontaneous mutations in the genome and alter its evolutionary trajectory.
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Evolutionary stasis of a deep subsurface microbial lineage. THE ISME JOURNAL 2021; 15:2830-2842. [PMID: 33824425 PMCID: PMC8443664 DOI: 10.1038/s41396-021-00965-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 02/26/2021] [Accepted: 03/15/2021] [Indexed: 02/01/2023]
Abstract
Sulfate-reducing bacteria Candidatus Desulforudis audaxviator (CDA) were originally discovered in deep fracture fluids accessed via South African gold mines and have since been found in geographically widespread deep subsurface locations. In order to constrain models for subsurface microbial evolution, we compared CDA genomes from Africa, North America and Eurasia using single cell genomics. Unexpectedly, 126 partial single amplified genomes from the three continents, a complete genome from of an isolate from Eurasia, and metagenome-assembled genomes from Africa and Eurasia shared >99.2% average nucleotide identity, low frequency of SNP's, and near-perfectly conserved prophages and CRISPRs. Our analyses reject sample cross-contamination, recent natural dispersal, and unusually strong purifying selection as likely explanations for these unexpected results. We therefore conclude that the analyzed CDA populations underwent only minimal evolution since their physical separation, potentially as far back as the breakup of Pangea between 165 and 55 Ma ago. High-fidelity DNA replication and repair mechanisms are the most plausible explanation for the highly conserved genome of CDA. CDA presents a stark contrast to the current model organisms in microbial evolutionary studies, which often develop adaptive traits over far shorter periods of time.
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14
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Auboeuf D. The Physics-Biology continuum challenges darwinism: Evolution is directed by the homeostasis-dependent bidirectional relation between genome and phenotype. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 167:121-139. [PMID: 34097984 DOI: 10.1016/j.pbiomolbio.2021.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 05/19/2021] [Accepted: 05/31/2021] [Indexed: 10/21/2022]
Abstract
The physics-biology continuum relies on the fact that life emerged from prebiotic molecules. Here, I argue that life emerged from the coupling between nucleic acid and protein synthesis during which proteins (or proto-phenotypes) maintained the physicochemical parameter equilibria (or proto-homeostasis) in the proximity of their encoding nucleic acids (or proto-genomes). This protected the proto-genome physicochemical integrity (i.e., atomic composition) from environmental physicochemical constraints, and therefore increased the probability of reproducing the proto-genome without variation. From there, genomes evolved depending on the biological activities they generated in response to environmental fluctuations. Thus, a genome maintaining homeostasis (i.e., internal physicochemical parameter equilibria), despite and in response to environmental fluctuations, maintains its physicochemical integrity and has therefore a higher probability to be reproduced without variation. Consequently, descendants have a higher probability to share the same phenotype than their parents. Otherwise, the genome is modified during replication as a consequence of the imbalance of the internal physicochemical parameters it generates, until new mutation-deriving biological activities maintain homeostasis in offspring. In summary, evolution depends on feedforward and feedback loops between genome and phenotype, as the internal physicochemical conditions that a genome generates ─ through its derived phenotype in response to environmental fluctuations ─ in turn either guarantee its stability or direct its variation. Evolution may not be explained by the Darwinism-derived, unidirectional principle (random mutations-phenotypes-natural selection) but rather by the bidirectional relationship between genome and phenotype, in which the phenotype in interaction with the environment directs the evolution of the genome it derives from.
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Affiliation(s)
- Didier Auboeuf
- ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell, 46 Allée D'Italie, Site Jacques Monod, F-69007, Lyon, France.
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15
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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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16
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Li Y, Shen QS, Peng Q, Ding W, Zhang J, Zhong X, An NA, Ji M, Zhou WZ, Li CY. Polyadenylation-related isoform switching in human evolution revealed by full-length transcript structure. Brief Bioinform 2021; 22:6273384. [PMID: 33973996 PMCID: PMC8574621 DOI: 10.1093/bib/bbab157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/22/2021] [Accepted: 04/04/2021] [Indexed: 11/26/2022] Open
Abstract
Rhesus macaque is a unique nonhuman primate model for human evolutionary and translational study, but the error-prone gene models critically limit its applications. Here, we de novo defined full-length macaque gene models based on single molecule, long-read transcriptome sequencing in four macaque tissues (frontal cortex, cerebellum, heart and testis). Overall, 8 588 227 poly(A)-bearing complementary DNA reads with a mean length of 14 106 nt were generated to compile the backbone of macaque transcripts, with the fine-scale structures further refined by RNA sequencing and cap analysis gene expression sequencing data. In total, 51 605 macaque gene models were accurately defined, covering 89.7% of macaque or 75.7% of human orthologous genes. Based on the full-length gene models, we performed a human–macaque comparative analysis on polyadenylation (PA) regulation. Using macaque and mouse as outgroup species, we identified 79 distal PA events newly originated in humans and found that the strengthening of the distal PA sites, rather than the weakening of the proximal sites, predominantly contributes to the origination of these human-specific isoforms. Notably, these isoforms are selectively constrained in general and contribute to the temporospatially specific reduction of gene expression, through the tinkering of previously existed mechanisms of nuclear retention and microRNA (miRNA) regulation. Overall, the protocol and resource highlight the application of bioinformatics in integrating multilayer genomics data to provide an intact reference for model animal studies, and the isoform switching detected may constitute a hitherto underestimated regulatory layer in shaping the human-specific transcriptome and phenotypic changes.
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Affiliation(s)
- Yumei Li
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Qing Sunny Shen
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Qi Peng
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, Beijing, China.,College of Future Technology, Peking University, Beijing, China
| | - Wanqiu Ding
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, Beijing, China.,College of Future Technology, Peking University, Beijing, China
| | - Jie Zhang
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, Beijing, China.,College of Future Technology, Peking University, Beijing, China
| | - Xiaoming Zhong
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Ni A An
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, Beijing, China.,College of Future Technology, Peking University, Beijing, China
| | - Mingjun Ji
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, Beijing, China.,College of Future Technology, Peking University, Beijing, China
| | - Wei-Zhen Zhou
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, Beijing, China
| | - Chuan-Yun Li
- Laboratory of Bioinformatics and Genomic Medicine, Institute of Molecular Medicine, Peking University, Beijing, China.,College of Future Technology, Peking University, Beijing, China
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17
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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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18
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Belfield EJ, Brown C, Ding ZJ, Chapman L, Luo M, Hinde E, van Es SW, Johnson S, Ning Y, Zheng SJ, Mithani A, Harberd NP. Thermal stress accelerates Arabidopsis thaliana mutation rate. Genome Res 2020; 31:40-50. [PMID: 33334733 PMCID: PMC7849391 DOI: 10.1101/gr.259853.119] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 10/28/2020] [Indexed: 01/07/2023]
Abstract
Mutations are the source of both genetic diversity and mutational load. However, the effects of increasing environmental temperature on plant mutation rates and relative impact on specific mutational classes (e.g., insertion/deletion [indel] vs. single nucleotide variant [SNV]) are unknown. This topic is important because of the poorly defined effects of anthropogenic global temperature rise on biological systems. Here, we show the impact of temperature increase on Arabidopsis thaliana mutation, studying whole genome profiles of mutation accumulation (MA) lineages grown for 11 successive generations at 29°C. Whereas growth of A. thaliana at standard temperature (ST; 23°C) is associated with a mutation rate of 7 × 10−9 base substitutions per site per generation, growth at stressful high temperature (HT; 29°C) is highly mutagenic, increasing the mutation rate to 12 × 10−9. SNV frequency is approximately two- to threefold higher at HT than at ST, and HT-growth causes an ∼19- to 23-fold increase in indel frequency, resulting in a disproportionate increase in indels (vs. SNVs). Most HT-induced indels are 1–2 bp in size and particularly affect homopolymeric or dinucleotide A or T stretch regions of the genome. HT-induced indels occur disproportionately in nucleosome-free regions, suggesting that much HT-induced mutational damage occurs during cell-cycle phases when genomic DNA is packaged into nucleosomes. We conclude that stressful experimental temperature increases accelerate plant mutation rates and particularly accelerate the rate of indel mutation. Increasing environmental temperatures are thus likely to have significant mutagenic consequences for plants growing in the wild and may, in particular, add detrimentally to mutational load.
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Affiliation(s)
- Eric J Belfield
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Carly Brown
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Zhong Jie Ding
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Lottie Chapman
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Faculty of Sciences, University of Geneva, Geneva 1211, Switzerland
| | - Mengqian Luo
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Eleanor Hinde
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Sam W van Es
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, SE-901 87 Umeå, Sweden
| | - Sophie Johnson
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Youzheng Ning
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Shao Jian Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Aziz Mithani
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences (LUMS), DHA, Lahore 54792, Pakistan
| | - Nicholas P Harberd
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
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19
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Chen H, Liang H. A High-Resolution Map of Human Enhancer RNA Loci Characterizes Super-enhancer Activities in Cancer. Cancer Cell 2020; 38:701-715.e5. [PMID: 33007258 PMCID: PMC7658066 DOI: 10.1016/j.ccell.2020.08.020] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 07/21/2020] [Accepted: 08/28/2020] [Indexed: 12/20/2022]
Abstract
Although enhancers play critical roles in cancer, quantifying enhancer activities in clinical samples remains challenging, especially for super-enhancers. Enhancer activities can be inferred from enhancer RNA (eRNA) signals, which requires enhancer transcription loci definition. Only a small proportion of human eRNA loci has been precisely identified, limiting investigations of enhancer-mediated oncogenic mechanisms. Here, we characterize super-enhancer regions using aggregated RNA sequencing (RNA-seq) data from large cohorts. Super-enhancers usually contain discrete loci featuring sharp eRNA expression peaks. We identify >300,000 eRNA loci in ∼377 Mb super-enhancer regions that are regulated by evolutionarily conserved, well-positioned nucleosomes and are frequently dysregulated in cancer. The eRNAs provide explanatory power for cancer phenotypes beyond that provided by mRNA expression through resolving intratumoral heterogeneity with enhancer cell-type specificity. Our study provides a high-resolution map of eRNA loci through which super-enhancer activities can be quantified by RNA-seq and a user-friendly data portal, enabling a broad range of biomedical investigations.
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Affiliation(s)
- Han Chen
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Han Liang
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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20
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Lei H, Tao K. Somatic mutations in colorectal cancer are associated with the epigenetic modifications. J Cell Mol Med 2020; 24:11828-11836. [PMID: 32865336 PMCID: PMC7579689 DOI: 10.1111/jcmm.15799] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 07/22/2020] [Accepted: 08/09/2020] [Indexed: 01/13/2023] Open
Abstract
Colorectal cancer (CRC) mostly arises from progressive accumulation of somatic mutations within cells. Most commonly mutated genes like TP53, APC and KRAS can promote survival and proliferation of cancer cells. Although the molecular alterations and landscape of some specific mutations in CRC are well known, the presence of a somatic mutation signature related to genomic regions and epigenetic markers remain unclear. To find the signatures from a random distribution of somatic mutations in CRCs, we carried out enrichment analysis in different genomic regions and identified peaks of epigenetic markers. We validated that the mutation frequency in miRNA is dramatically higher than in flanking genomic regions. Moreover, we observed that somatic mutations in CRC and colon cancer cell lines are significantly enriched in CTCF binding sites. We also found these mutations are enriched for H3K27me3 in both normal sigmoid colon and colon cancer cell lines. Taken together, our findings suggest that there are some common somatic mutations signatures which provide new directions to study CRC.
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Affiliation(s)
- Hongwei Lei
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kaixiong Tao
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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21
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Li C, Luscombe NM. Nucleosome positioning stability is a modulator of germline mutation rate variation across the human genome. Nat Commun 2020; 11:1363. [PMID: 32170069 PMCID: PMC7070026 DOI: 10.1038/s41467-020-15185-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 02/23/2020] [Indexed: 02/08/2023] Open
Abstract
Nucleosome organization has been suggested to affect local mutation rates in the genome. However, the lack of de novo mutation and high-resolution nucleosome data has limited the investigation of this hypothesis. Additionally, analyses using indirect mutation rate measurements have yielded contradictory and potentially confounding results. Here, we combine data on >300,000 human de novo mutations with high-resolution nucleosome maps and find substantially elevated mutation rates around translationally stable (‘strong’) nucleosomes. We show that the mutational mechanisms affected by strong nucleosomes are low-fidelity replication, insufficient mismatch repair and increased double-strand breaks. Strong nucleosomes preferentially locate within young SINE/LINE transposons, suggesting that when subject to increased mutation rates, transposons are then more rapidly inactivated. Depletion of strong nucleosomes in older transposons suggests frequent positioning changes during evolution. The findings have important implications for human genetics and genome evolution. Nucleosome organization has been suggested to affect local mutation rates in the genome. Here, the authors analyse data on >300,000 human de novo mutations and high-resolution nucleosome maps and provide evidence that nucleosome positioning stability modulates germline mutation rate variation across the human genome.
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Affiliation(s)
- Cai Li
- The Francis Crick Institute, London, NW1 1AT, UK. .,School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China.
| | - Nicholas M Luscombe
- The Francis Crick Institute, London, NW1 1AT, UK.,Okinawa Institute of Science & Technology Graduate University, Okinawa, 904-0495, Japan.,UCL Genetics Institute, University College London, London, WC1E 6BT, UK
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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: 105] [Impact Index Per Article: 26.3] [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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Drinnenberg IA, Berger F, Elsässer SJ, Andersen PR, Ausió J, Bickmore WA, Blackwell AR, Erwin DH, Gahan JM, Gaut BS, Harvey ZH, Henikoff S, Kao JY, Kurdistani SK, Lemos B, Levine MT, Luger K, Malik HS, Martín-Durán JM, Peichel CL, Renfree MB, Rutowicz K, Sarkies P, Schmitz RJ, Technau U, Thornton JW, Warnecke T, Wolfe KH. EvoChromo: towards a synthesis of chromatin biology and evolution. Development 2019; 146:146/19/dev178962. [PMID: 31558570 DOI: 10.1242/dev.178962] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Over the past few years, interest in chromatin and its evolution has grown. To further advance these interests, we organized a workshop with the support of The Company of Biologists to debate the current state of knowledge regarding the origin and evolution of chromatin. This workshop led to prospective views on the development of a new field of research that we term 'EvoChromo'. In this short Spotlight article, we define the breadth and expected impact of this new area of scientific inquiry on our understanding of both chromatin and evolution.
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Affiliation(s)
- Ines A Drinnenberg
- Institut Curie, Paris Sciences et Lettres Research University, Centre National de la Recherche Scientifique UMR 3664, Paris 75005, France
| | - Frédéric Berger
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Simon J Elsässer
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden
| | - Peter R Andersen
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Dr. Bohrgasse 3, 1030 Vienna, Austria
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, V8W 3P6, Canada
| | - Wendy A Bickmore
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | | | - Douglas H Erwin
- Department of Paleobiology, MRC-121, National Museum of Natural History, Washington, DC 20013-7012, USA
| | - James M Gahan
- Sars Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgt. 55, 5008 Bergen, Norway
| | - Brandon S Gaut
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Zachary H Harvey
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Steven Henikoff
- Division of Basic Sciences and Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Joyce Y Kao
- Center for Genomics and Systems Biology, New York University, 12 Waverly Place, New York, NY 10003, USA.,Institute of Molecular Systems Biology, Swiss Federal Institute of Technology (ETH) Zürich, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Siavash K Kurdistani
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Bernardo Lemos
- Program in Molecular and Integrative Physiological Sciences, Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
| | - Mia T Levine
- Department of Biology, Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Karolin Luger
- Howard Hughes Medical Institute and Department of Biochemistry, CU Boulder, Boulder, CO 80303, USA
| | - Harmit S Malik
- Division of Basic Sciences and Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - José M Martín-Durán
- Queen Mary University of London, School of Biological and Chemical Sciences, Mile End Road, London E1 4NS, UK
| | - Catherine L Peichel
- Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Marilyn B Renfree
- School of BioSciences, The University of Melbourne, Melbourne, 3010 VIC, Australia
| | - Kinga Rutowicz
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, 8092 Zürich, Switzerland
| | - Peter Sarkies
- MRC London Institute of Medical Sciences and Institute of Clinical Sciences, IMperial College London, Du Cane Road, London W12 0NN, UK
| | - Robert J Schmitz
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Ulrich Technau
- Department for Molecular Evolution and Development, Centre of Organismal Systems Biology, University of Vienna, Vienna A-1090, Austria
| | - Joseph W Thornton
- Department of Human Genetics, and Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637 USA
| | - Tobias Warnecke
- MRC London Institute of Medical Sciences and Institute of Clinical Sciences, IMperial College London, Du Cane Road, London W12 0NN, UK
| | - Kenneth H Wolfe
- Conway Institute and School of Medicine, University College Dublin, Dublin 4, Ireland
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24
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Somatic and Germline Mutation Periodicity Follow the Orientation of the DNA Minor Groove around Nucleosomes. Cell 2019; 175:1074-1087.e18. [PMID: 30388444 DOI: 10.1016/j.cell.2018.10.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 08/27/2018] [Accepted: 10/01/2018] [Indexed: 12/11/2022]
Abstract
Mutation rates along the genome are highly variable and influenced by several chromatin features. Here, we addressed how nucleosomes, the most pervasive chromatin structure in eukaryotes, affect the generation of mutations. We discovered that within nucleosomes, the somatic mutation rate across several tumor cohorts exhibits a strong 10 base pair (bp) periodicity. This periodic pattern tracks the alternation of the DNA minor groove facing toward and away from the histones. The strength and phase of the mutation rate periodicity are determined by the mutational processes active in tumors. We uncovered similar periodic patterns in the genetic variation among human and Arabidopsis populations, also detectable in their divergence from close species, indicating that the same principles underlie germline and somatic mutation rates. We propose that differential DNA damage and repair processes dependent on the minor groove orientation in nucleosome-bound DNA contribute to the 10-bp periodicity in AT/CG content in eukaryotic genomes.
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25
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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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26
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Hu CM, Tien SC, Hsieh PK, Jeng YM, Chang MC, Chang YT, Chen YJ, Chen YJ, Lee EYHP, Lee WH. High Glucose Triggers Nucleotide Imbalance through O-GlcNAcylation of Key Enzymes and Induces KRAS Mutation in Pancreatic Cells. Cell Metab 2019; 29:1334-1349.e10. [PMID: 30853214 DOI: 10.1016/j.cmet.2019.02.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 12/20/2018] [Accepted: 02/12/2019] [Indexed: 12/13/2022]
Abstract
KRAS mutations are the earliest events found in approximately 90% of pancreatic ductal adenocarcinomas (PDACs). However, little is known as to why KRAS mutations preferentially occur in PDACs and what processes/factors generate these mutations. While abnormal carbohydrate metabolism is associated with a high risk of pancreatic cancer, it remains elusive whether a direct relationship between KRAS mutations and sugar metabolism exists. Here, we show that under high-glucose conditions, cellular O-GlcNAcylation is significantly elevated in pancreatic cells that exhibit lower phosphofructokinase (PFK) activity than other cell types. This post-translational modification specifically compromises the ribonucleotide reductase (RNR) activity, leading to deficiency in dNTP pools, genomic DNA alterations with KRAS mutations, and cellular transformation. These results establish a mechanistic link between a perturbed sugar metabolism and genomic instability that induces de novo oncogenic KRAS mutations preferentially in pancreatic cells.
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MESH Headings
- Acetylation/drug effects
- Acetylglucosamine/metabolism
- Acetyltransferases/metabolism
- Adult
- Aged
- Animals
- Carcinoma, Pancreatic Ductal/chemically induced
- Carcinoma, Pancreatic Ductal/genetics
- Carcinoma, Pancreatic Ductal/metabolism
- Carcinoma, Pancreatic Ductal/pathology
- Cell Transformation, Neoplastic/chemically induced
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cells, Cultured
- DNA Damage/genetics
- Dose-Response Relationship, Drug
- Enzymes/genetics
- Enzymes/metabolism
- Female
- Glucose/adverse effects
- Glucose/pharmacology
- HEK293 Cells
- Humans
- Infant, Newborn
- Male
- Metabolic Networks and Pathways/drug effects
- Metabolic Networks and Pathways/genetics
- Mice
- Mice, Inbred C57BL
- Middle Aged
- Mutagenesis/drug effects
- Mutation/drug effects
- Nucleotides/metabolism
- Pancreas/drug effects
- Pancreas/metabolism
- Pancreatic Neoplasms/chemically induced
- Pancreatic Neoplasms/genetics
- Pancreatic Neoplasms/metabolism
- Pancreatic Neoplasms/pathology
- Protein Processing, Post-Translational/drug effects
- Proto-Oncogene Proteins p21(ras)/genetics
- Proto-Oncogene Proteins p21(ras)/metabolism
- Young Adult
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Affiliation(s)
- Chun-Mei Hu
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan.
| | - Sui-Chih Tien
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Ping-Kun Hsieh
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Yung-Ming Jeng
- Department of Pathology, National Taiwan University Hospital, Taipei 10041, Taiwan
| | - Ming-Chu Chang
- Department of Internal Medicine, National Taiwan University Hospital, Taipei 10041, Taiwan
| | - Yu-Ting Chang
- Department of Internal Medicine, National Taiwan University Hospital, Taipei 10041, Taiwan
| | - Yi-Ju Chen
- Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Yu-Ju Chen
- Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Eva Y-H P Lee
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Wen-Hwa Lee
- Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan; Drug Development Center, China Medical University, Taichung 40402, Taiwan.
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27
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Yuan W, Zhou J, Tong J, Zhuo W, Wang L, Li Y, Sun Q, Qian W. ALBA protein complex reads genic R-loops to maintain genome stability in Arabidopsis. SCIENCE ADVANCES 2019; 5:eaav9040. [PMID: 31106272 PMCID: PMC6520018 DOI: 10.1126/sciadv.aav9040] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 04/02/2019] [Indexed: 05/19/2023]
Abstract
The R-loop, composed of a DNA-RNA hybrid and the displaced single-stranded DNA, regulates diverse cellular processes. However, how cellular R-loops are recognized remains poorly understood. Here, we report the discovery of the evolutionally conserved ALBA proteins (AtALBA1 and AtALBA2) functioning as the genic R-loop readers in Arabidopsis. While AtALBA1 binds to the DNA-RNA hybrid, AtALBA2 associates with single-stranded DNA in the R-loops in vitro. In vivo, these two proteins interact and colocalize in the nucleus, where they preferentially bind to genic regions with active epigenetic marks in an R-loop-dependent manner. Depletion of AtALBA1 or AtALBA2 results in hypersensitivity of plants to DNA damaging agents. The formation of DNA breaks in alba mutants originates from unprotected R-loops. Our results reveal that the AtALBA1 and AtALBA2 protein complex is the genic R-loop reader crucial for genome stability in Arabidopsis.
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Affiliation(s)
- Wei Yuan
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jincong Zhou
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Jinjin Tong
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wanqing Zhuo
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Lishuan Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yan Li
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Qianwen Sun
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
- Corresponding author. (Q.S.); (W.Q.)
| | - Weiqiang Qian
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- Corresponding author. (Q.S.); (W.Q.)
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28
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Brown AJ, Mao P, Smerdon MJ, Wyrick JJ, Roberts SA. Nucleosome positions establish an extended mutation signature in melanoma. PLoS Genet 2018; 14:e1007823. [PMID: 30485262 PMCID: PMC6287878 DOI: 10.1371/journal.pgen.1007823] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 12/10/2018] [Accepted: 11/09/2018] [Indexed: 12/24/2022] Open
Abstract
Ultraviolet (UV) light-induced mutations are unevenly distributed across skin cancer genomes, but the molecular mechanisms responsible for this heterogeneity are not fully understood. Here, we assessed how nucleosome structure impacts the positions of UV-induced mutations in human melanomas. Analysis of mutation positions from cutaneous melanomas within strongly positioned nucleosomes revealed a striking ~10 base pair (bp) oscillation in mutation density with peaks occurring at dinucleotides facing away from the histone octamer. Additionally, higher mutation density at the nucleosome dyad generated an overarching “translational curvature” across the 147 bp of DNA that constitutes the nucleosome core particle. This periodicity and curvature cannot be explained by sequence biases in nucleosomal DNA. Instead, our genome-wide map of UV-induced cyclobutane pyrimidine dimers (CPDs) indicates that CPD formation is elevated at outward facing dinucleotides, mirroring the oscillation of mutation density within nucleosome-bound DNA. Nucleotide excision repair (NER) activity, as measured by XR-seq, inversely correlated with the curvature of mutation density associated with the translational setting of the nucleosome. While the 10 bp periodicity of mutations is maintained across nucleosomes regardless of chromatin state, histone modifications, and transcription levels, overall mutation density and curvature across the core particle increased with lower transcription levels. Our observations suggest structural conformations of DNA promote CPD formation at specific sites within nucleosomes, and steric hindrance progressively limits lesion repair towards the nucleosome dyad. Both mechanisms create a unique extended mutation signature within strongly positioned nucleosomes across the human genome. UV-induced mutations are abundant and heterogeneously distributed across melanoma genomes. Understanding the mechanisms that produce this heterogeneity may help decipher which mutations drive the cancer phenotype. While it is known that mutation density correlates with chromatin compaction on a large scale, recent studies have suggested that local chromatin structure impacts mutation distribution in ways previously undetected. We therefore examined the distribution of melanoma mutations in strongly positioned nucleosomes where we observed a striking oscillatory and curvature pattern. UV lesion formation appeared to be responsible for mutation oscillation, despite active repair occurring in the nucleosome core particle. However, more CPD lesions are removed near the edges of nucleosomes, and thus generated an overall translational curvature in mutation density.
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Affiliation(s)
- Alexander J. Brown
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States of America
| | - Peng Mao
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States of America
| | - Michael J. Smerdon
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States of America
| | - John J. Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States of America
- Center for Reproductive Biology, Washington State University, Pullman, WA, United States of America
- * E-mail: (JJW); (SAR)
| | - Steven A. Roberts
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States of America
- Center for Reproductive Biology, Washington State University, Pullman, WA, United States of America
- * E-mail: (JJW); (SAR)
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29
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Duan C, Huan Q, Chen X, Wu S, Carey LB, He X, Qian W. Reduced intrinsic DNA curvature leads to increased mutation rate. Genome Biol 2018; 19:132. [PMID: 30217230 PMCID: PMC6138893 DOI: 10.1186/s13059-018-1525-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 09/05/2018] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Mutation rates vary across the genome. Many trans factors that influence mutation rates have been identified, as have specific sequence motifs at the 1-7-bp scale, but cis elements remain poorly characterized. The lack of understanding regarding why different sequences have different mutation rates hampers our ability to identify positive selection in evolution and to identify driver mutations in tumorigenesis. RESULTS Here, we use a combination of synthetic genes and sequences of thousands of isolated yeast colonies to show that intrinsic DNA curvature is a major cis determinant of mutation rate. Mutation rate negatively correlates with DNA curvature within genes, and a 10% decrease in curvature results in a 70% increase in mutation rate. Consistently, both yeast and humans accumulate mutations in regions with small curvature. We further show that this effect is due to differences in the intrinsic mutation rate, likely due to differences in mutagen sensitivity and not due to differences in the local activity of DNA repair. CONCLUSIONS Our study establishes a framework for understanding the cis properties of DNA sequence in modulating the local mutation rate and identifies a novel causal source of non-uniform mutation rates across the genome.
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Affiliation(s)
- Chaorui Duan
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.,Key Laboratory of Genetic Network Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qing Huan
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.,Key Laboratory of Genetic Network Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xiaoshu Chen
- Human Genome Research Institute and Department of Medical Genetics, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Shaohuan Wu
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.,Key Laboratory of Genetic Network Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lucas B Carey
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, 08003, Barcelona, Spain
| | - Xionglei He
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Wenfeng Qian
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China. .,Key Laboratory of Genetic Network Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
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30
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Farack L, Egozi A, Itzkovitz S. Single molecule approaches for studying gene regulation in metabolic tissues. Diabetes Obes Metab 2018; 20 Suppl 2:145-156. [PMID: 30230176 DOI: 10.1111/dom.13390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 05/16/2018] [Accepted: 05/30/2018] [Indexed: 12/25/2022]
Abstract
Gene expression in metabolic tissues can be regulated at multiple levels, ranging from the control of promoter accessibilities, transcription rates, mRNA degradation rates and mRNA localization. Modulating these processes can differentially affect important performance criteria of cells. These include precision, cellular economy, rapid response and maintenance of DNA integrity. In this review we will describe how distinct strategies of gene regulation impact the trade-offs between the cells' performance criteria. We will highlight tools based on single molecule visualization of transcripts that can be used to measure promoter states, transcription rates and mRNA degradation rates in intact tissues. These approaches revealed surprising recurrent patterns in mammalian tissues, that include transcriptional bursting, nuclear retention of mRNA, and coordination of mRNA lifetimes to facilitate rapid adaptation to changing metabolic inputs. The ability to characterize gene expression at the single molecule level can uncover the design principles of gene regulation in metabolic tissues such as the liver and the pancreas.
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Affiliation(s)
- Lydia Farack
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Adi Egozi
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Shalev Itzkovitz
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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31
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Hurst LD, Batada NN. Depletion of somatic mutations in splicing-associated sequences in cancer genomes. Genome Biol 2017; 18:213. [PMID: 29115978 PMCID: PMC5678748 DOI: 10.1186/s13059-017-1337-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 10/12/2017] [Indexed: 01/01/2023] Open
Abstract
Background An important goal of cancer genomics is to identify systematically cancer-causing mutations. A common approach is to identify sites with high ratios of non-synonymous to synonymous mutations; however, if synonymous mutations are under purifying selection, this methodology leads to identification of false-positive mutations. Here, using synonymous somatic mutations (SSMs) identified in over 4000 tumours across 15 different cancer types, we sought to test this assumption by focusing on coding regions required for splicing. Results Exon flanks, which are enriched for sequences required for splicing fidelity, have ~ 17% lower SSM density compared to exonic cores, even after excluding canonical splice sites. While it is impossible to eliminate a mutation bias of unknown cause, multiple lines of evidence support a purifying selection model above a mutational bias explanation. The flank/core difference is not explained by skewed nucleotide content, replication timing, nucleosome occupancy or deficiency in mismatch repair. The depletion is not seen in tumour suppressors, consistent with their role in positive tumour selection, but is otherwise observed in cancer-associated and non-cancer genes, both essential and non-essential. Consistent with a role in splicing modulation, exonic splice enhancers have a lower SSM density before and after controlling for nucleotide composition; moreover, flanks at the 5’ end of the exons have significantly lower SSM density than at the 3’ end. Conclusions These results suggest that the observable mutational spectrum of cancer genomes is not simply a product of various mutational processes and positive selection, but might also be shaped by negative selection. Electronic supplementary material The online version of this article (doi:10.1186/s13059-017-1337-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Laurence D Hurst
- The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK
| | - Nizar N Batada
- Institute for Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, UK.
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32
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Lynch M, Ackerman MS, Gout JF, Long H, Sung W, Thomas WK, Foster PL. Genetic drift, selection and the evolution of the mutation rate. Nat Rev Genet 2017; 17:704-714. [PMID: 27739533 DOI: 10.1038/nrg.2016.104] [Citation(s) in RCA: 437] [Impact Index Per Article: 62.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
As one of the few cellular traits that can be quantified across the tree of life, DNA-replication fidelity provides an excellent platform for understanding fundamental evolutionary processes. Furthermore, because mutation is the ultimate source of all genetic variation, clarifying why mutation rates vary is crucial for understanding all areas of biology. A potentially revealing hypothesis for mutation-rate evolution is that natural selection primarily operates to improve replication fidelity, with the ultimate limits to what can be achieved set by the power of random genetic drift. This drift-barrier hypothesis is consistent with comparative measures of mutation rates, provides a simple explanation for the existence of error-prone polymerases and yields a formal counter-argument to the view that selection fine-tunes gene-specific mutation rates.
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Affiliation(s)
- Michael Lynch
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
| | - Matthew S Ackerman
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
| | - Jean-Francois Gout
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
| | - Hongan Long
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
| | - Way Sung
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
| | - W Kelley Thomas
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire 03824, USA
| | - Patricia L Foster
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
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33
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Lim B, Mun J, Kim SY. Intrinsic Molecular Processes: Impact on Mutagenesis. Trends Cancer 2017; 3:357-371. [PMID: 28718413 DOI: 10.1016/j.trecan.2017.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 03/23/2017] [Accepted: 03/23/2017] [Indexed: 02/07/2023]
Abstract
Mutations provide resources for genome evolution by generating genetic variability. In addition, mutations act as a driving force leading to disease pathogenesis, and thus have important implications for disease diagnosis, prognosis, and treatment. Understanding the mechanisms underlying how mutations occur is therefore of prime importance for elucidating evolutionary and pathogenic processes. Recent genomics studies have revealed that mutations occur non-randomly across the human genome. In particular, the distribution of mutations is highly associated with intrinsic molecular processes including transcription, chromatin organization, DNA replication timing, and DNA repair. Interplay between intrinsic processes and extrinsic mutagenic exposure may thus imprint a characteristic mutational landscape on tumors. We discuss the impact of intrinsic molecular processes on mutation acquisition in cancer.
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Affiliation(s)
- Byungho Lim
- Research Center for Drug Discovery Technology, Division of Drug Discovery Research, Korea Research Institute of Chemical Technology, Daejeon, Korea
| | - Jihyeob Mun
- Personalized Genomic Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Korea; Department of Functional Genomics, University of Science and Technology, Daejeon, Korea
| | - Seon-Young Kim
- Personalized Genomic Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Korea; Department of Functional Genomics, University of Science and Technology, Daejeon, Korea.
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34
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Lim B, Mun J, Kim YS, Kim SY. Variability in Chromatin Architecture and Associated DNA Repair at Genomic Positions Containing Somatic Mutations. Cancer Res 2017; 77:2822-2833. [PMID: 28408367 DOI: 10.1158/0008-5472.can-16-3033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Revised: 01/20/2017] [Accepted: 03/31/2017] [Indexed: 11/16/2022]
Abstract
Dynamic chromatin structures result in differential chemical reactivity to mutational processes throughout the genome. To identify chromatin features responsible for mutagenesis, we compared chromatin architecture around single-nucleotide variants (SNV), insertion/deletions (indels), and their context-matched, nonmutated positions. We found epigenetic differences between genomic regions containing missense SNVs and those containing frameshift indels across multiple cancer types. Levels of active histone marks were higher around frameshift indels than around missense SNV, whereas repressive histone marks exhibited the reverse trend. Accumulation of repressive histone marks and nucleosomes distinguished mutated positions (both SNV and indels) from the context-matched, nonmutated positions, whereas active marks were associated with substitution- and cancer type-specific mutagenesis. We also explained mutagenesis based on genome maintenance mechanisms, including nucleotide excision repair (NER), mismatch repair (MMR), and DNA polymerase epsilon (POLE). Regional NER variation correlated strongly with chromatin features; NER machineries exhibited shifted or depleted binding around SNV, resulting in decreased NER at mutation positions, especially at sites of recurrent mutations. MMR-deficient tumors selectively acquired SNV in regions with high active histone marks, especially H3K36me3, whereas POLE-deficient tumors selectively acquired indels and SNV in regions with low active histone marks. These findings demonstrate the importance of fine-scaled chromatin structures and associated DNA repair mechanisms in mutagenesis. Cancer Res; 77(11); 2822-33. ©2017 AACR.
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Affiliation(s)
- Byungho Lim
- Personalized Genomic Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea
| | - Jihyeob Mun
- Personalized Genomic Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea.,Department of Functional Genomics, University of Science and Technology, Daejeon, Korea
| | - Yong Sung Kim
- Department of Functional Genomics, University of Science and Technology, Daejeon, Korea.,Genome Editing Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea
| | - Seon-Young Kim
- Personalized Genomic Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea. .,Department of Functional Genomics, University of Science and Technology, Daejeon, Korea
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35
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Manskikh VN. Do External or Internal Factors Lead to Tumor Development? It Is Still Unknown. BIOCHEMISTRY. BIOKHIMIIA 2017; 82:81-85. [PMID: 28320290 DOI: 10.1134/s0006297917010096] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Arguments supporting the "bad luck" hypothesis presented by C. Tomasetti and B. Vogelstein ((2015) Science, 347, 78-81) and A. V. Lichtenstein ((2017) Biochemistry (Moscow), 82, 75-80) are critically discussed. Those arguments are not sufficient for recognition of the "bad luck" hypothesis and the leading role of internal factors in spontaneous tumor development.
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Affiliation(s)
- V N Manskikh
- Lomonosov Moscow State University, Faculty of Bioengineering and Bioinformatics, Moscow, 119991, Russia.
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36
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Maree JP, Povelones ML, Clark DJ, Rudenko G, Patterton HG. Well-positioned nucleosomes punctuate polycistronic pol II transcription units and flank silent VSG gene arrays in Trypanosoma brucei. Epigenetics Chromatin 2017; 10:14. [PMID: 28344657 PMCID: PMC5359979 DOI: 10.1186/s13072-017-0121-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 03/14/2017] [Indexed: 12/18/2022] Open
Abstract
Background The compaction of DNA in chromatin in eukaryotes allowed the expansion of genome size and coincided with significant evolutionary diversification. However, chromatin generally represses DNA function, and mechanisms coevolved to regulate chromatin structure and its impact on DNA. This included the selection of specific nucleosome positions to modulate accessibility to the DNA molecule. Trypanosoma brucei, a member of the Excavates supergroup, falls in an ancient evolutionary branch of eukaryotes and provides valuable insight into the organization of chromatin in early genomes. Results We have mapped nucleosome positions in T. brucei and identified important differences compared to other eukaryotes: The RNA polymerase II initiation regions in T. brucei do not exhibit pronounced nucleosome depletion, and show little evidence for defined −1 and +1 nucleosomes. In contrast, a well-positioned nucleosome is present directly on the splice acceptor sites within the polycistronic transcription units. The RNA polyadenylation sites were depleted of nucleosomes, with a single well-positioned nucleosome present immediately downstream of the predicted sites. The regions flanking the silent variant surface glycoprotein (VSG) gene cassettes showed extensive arrays of well-positioned nucleosomes, which may repress cryptic transcription initiation. The silent VSG genes themselves exhibited a less regular nucleosomal pattern in both bloodstream and procyclic form trypanosomes. The DNA replication origins, when present within silent VSG gene cassettes, displayed a defined nucleosomal organization compared with replication origins in other chromosomal core regions. Conclusions Our results indicate that some organizational features of chromatin are evolutionarily ancient, and may already have been present in the last eukaryotic common ancestor. Electronic supplementary material The online version of this article (doi:10.1186/s13072-017-0121-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Megan Lindsay Povelones
- Department of Biology, Pennsylvania State University (Brandywine Campus), Media, PA 19063 USA
| | - David Johannes Clark
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, MD USA
| | - Gloria Rudenko
- Department of Life Sciences, Imperial College London, South Kensington, London, SW7 2AZ UK
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37
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Xiong J, Gao S, Dui W, Yang W, Chen X, Taverna SD, Pearlman RE, Ashlock W, Miao W, Liu Y. Dissecting relative contributions of cis- and trans-determinants to nucleosome distribution by comparing Tetrahymena macronuclear and micronuclear chromatin. Nucleic Acids Res 2016; 44:10091-10105. [PMID: 27488188 PMCID: PMC5137421 DOI: 10.1093/nar/gkw684] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/21/2016] [Accepted: 07/24/2016] [Indexed: 02/06/2023] Open
Abstract
The ciliate protozoan Tetrahymena thermophila contains two types of structurally and functionally differentiated nuclei: the transcriptionally active somatic macronucleus (MAC) and the transcriptionally silent germ-line micronucleus (MIC). Here, we demonstrate that MAC features well-positioned nucleosomes downstream of transcription start sites and flanking splice sites. Transcription-associated trans-determinants promote nucleosome positioning in MAC. By contrast, nucleosomes in MIC are dramatically delocalized. Nucleosome occupancy in MAC and MIC are nonetheless highly correlated with each other, as well as with in vitro reconstitution and predictions based upon DNA sequence features, revealing unexpectedly strong contributions from cis-determinants. In particular, well-positioned nucleosomes are often matched with GC content oscillations. As many nucleosomes are coordinately accommodated by both cis- and trans-determinants, we propose that their distribution is shaped by the impact of these nucleosomes on the mutational and transcriptional landscape, and driven by evolutionary selection.
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Affiliation(s)
- Jie Xiong
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA,Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China,These authors contributed equally to this work as first authors
| | - Shan Gao
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China,These authors contributed equally to this work as first authors
| | - Wen Dui
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Wentao Yang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Xiao Chen
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Sean D. Taverna
- Department of Pharmacology and Molecular Sciences and The Center for Epigenetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ronald E. Pearlman
- Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada
| | - Wendy Ashlock
- Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada
| | - Wei Miao
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China,Correspondence may also be addressed to Wei Miao.
| | - Yifan Liu
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA,To whom correspondence should be addressed. Tel: +1 734 6154239;
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38
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Wang C, McPherson JR, Zhang LH, Rozen S, Sabapathy K. Transcription-associated mutation of lasR in Pseudomonas aeruginosa. DNA Repair (Amst) 2016; 46:9-19. [DOI: 10.1016/j.dnarep.2016.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/24/2016] [Accepted: 09/07/2016] [Indexed: 01/10/2023]
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Drillon G, Audit B, Argoul F, Arneodo A. Evidence of selection for an accessible nucleosomal array in human. BMC Genomics 2016; 17:526. [PMID: 27472913 PMCID: PMC4966569 DOI: 10.1186/s12864-016-2880-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 07/04/2016] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Recently, a physical model of nucleosome formation based on sequence-dependent bending properties of the DNA double-helix has been used to reveal some enrichment of nucleosome-inhibiting energy barriers (NIEBs) nearby ubiquitous human "master" replication origins. Here we use this model to predict the existence of about 1.6 millions NIEBs over the 22 human autosomes. RESULTS We show that these high energy barriers of mean size 153 bp correspond to nucleosome-depleted regions (NDRs) in vitro, as expected, but also in vivo. On either side of these NIEBs, we observe, in vivo and in vitro, a similar compacted nucleosome ordering, suggesting an absence of chromatin remodeling. This nucleosomal ordering strongly correlates with oscillations of the GC content as well as with the interspecies and intraspecies mutation profiles along these regions. Comparison of these divergence rates reveals the existence of both positive and negative selections linked to nucleosome positioning around these intrinsic NDRs. Overall, these NIEBs and neighboring nucleosomes cover 37.5 % of the human genome where nucleosome occupancy is stably encoded in the DNA sequence. These 1 kb-sized regions of intrinsic nucleosome positioning are equally found in GC-rich and GC-poor isochores, in early and late replicating regions, in intergenic and genic regions but not at gene promoters. CONCLUSION The source of selection pressure on the NIEBs has yet to be resolved in future work. One possible scenario is that these widely distributed chromatin patterns have been selected in human to impair the condensation of the nucleosomal array into the 30 nm chromatin fiber, so as to facilitate the epigenetic regulation of nuclear functions in a cell-type-specific manner.
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Affiliation(s)
- Guénola Drillon
- Univ Lyon, Ens de Lyon, Univ Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, Lyon, F-69342 France
| | - Benjamin Audit
- Univ Lyon, Ens de Lyon, Univ Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, Lyon, F-69342 France
| | - Françoise Argoul
- Univ Lyon, Ens de Lyon, Univ Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, Lyon, F-69342 France
- LOMA, Université de Bordeaux, CNRS, UMR 5798, 51 Cours de le Libération, Talence, F-33405 France
| | - Alain Arneodo
- Univ Lyon, Ens de Lyon, Univ Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, Lyon, F-69342 France
- LOMA, Université de Bordeaux, CNRS, UMR 5798, 51 Cours de le Libération, Talence, F-33405 France
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40
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Sun L, Zhang Y, Zhang Z, Zheng Y, Du L, Zhu B. Preferential Protection of Genetic Fidelity within Open Chromatin by the Mismatch Repair Machinery. J Biol Chem 2016; 291:17692-705. [PMID: 27382058 DOI: 10.1074/jbc.m116.719971] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Indexed: 12/30/2022] Open
Abstract
Epigenetic systems are well known for the roles they play in regulating the differential expression of the same genome in different cell types. However, epigenetic systems can also directly impact genomic integrity by protecting genetic sequences. Using an experimental evolutionary approach, we studied rates of mutation in the fission yeast Schizosaccharomyces pombe strains that lacked genes encoding several epigenetic regulators or mismatch repair components. We report that loss of a functional mismatch repair pathway in S. pombe resulted in the preferential enrichment of mutations in euchromatin, indicating that the mismatch repair machinery preferentially protected genetic fidelity in euchromatin. This preference is probably determined by differences in the accessibility of chromatin at distinct chromatin regions, which is supported by our observations that chromatin accessibility positively correlated with mutation rates in S. pombe or human cancer samples with deficiencies in mismatch repair. Importantly, such positive correlation was not observed in S. pombe strains or human cancer samples with functional mismatch repair machinery.
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Affiliation(s)
- Lue Sun
- From the Tsinghua University-Peking University-National Institute of Biological Sciences Joint Graduate Program, School of Life Sciences, Tsinghua University, Beijing 100084, the National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, the National Institute of Biological Sciences, Beijing 102206, and
| | - Yan Zhang
- the National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101
| | - Zhuqiang Zhang
- the National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101
| | - Yong Zheng
- the National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101
| | - Lilin Du
- the National Institute of Biological Sciences, Beijing 102206, and
| | - Bing Zhu
- the National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, the College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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41
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Sanchez R, Mackenzie SA. Genome-Wide Discriminatory Information Patterns of Cytosine DNA Methylation. Int J Mol Sci 2016; 17:ijms17060938. [PMID: 27322251 PMCID: PMC4926471 DOI: 10.3390/ijms17060938] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 05/16/2016] [Accepted: 06/02/2016] [Indexed: 12/11/2022] Open
Abstract
Cytosine DNA methylation (CDM) is a highly abundant, heritable but reversible chemical modification to the genome. Herein, a machine learning approach was applied to analyze the accumulation of epigenetic marks in methylomes of 152 ecotypes and 85 silencing mutants of Arabidopsis thaliana. In an information-thermodynamics framework, two measurements were used: (1) the amount of information gained/lost with the CDM changes I R and (2) the uncertainty of not observing a SNP L C R . We hypothesize that epigenetic marks are chromosomal footprints accounting for different ontogenetic and phylogenetic histories of individual populations. A machine learning approach is proposed to verify this hypothesis. Results support the hypothesis by the existence of discriminatory information (DI) patterns of CDM able to discriminate between individuals and between individual subpopulations. The statistical analyses revealed a strong association between the topologies of the structured population of Arabidopsis ecotypes based on I R and on LCR, respectively. A statistical-physical relationship between I R and L C R was also found. Results to date imply that the genome-wide distribution of CDM changes is not only part of the biological signal created by the methylation regulatory machinery, but ensures the stability of the DNA molecule, preserving the integrity of the genetic message under continuous stress from thermal fluctuations in the cell environment.
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Affiliation(s)
- Robersy Sanchez
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68588, USA.
| | - Sally A Mackenzie
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68588, USA.
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42
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BELPOMME DOMINIQUE, IRIGARAY PHILIPPE. Replicative random mutations as an unproven cause of cancer: A technical comment. Mol Clin Oncol 2016; 4:497-499. [PMID: 27073649 PMCID: PMC4812174 DOI: 10.3892/mco.2016.737] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 12/08/2015] [Indexed: 12/04/2022] Open
Abstract
A careful molecular biology, epidemiological and mathematical modelling reanalysis of the recently published study titled 'Cancer etiology. Variation in cancer risk among tissues can be explained by the number of stem cell divisions' by Cristian Tomasetti and Bert Vogelstein, which was published on January 2, 2015 in the distinguished journal Science, led to the conclusion that, contrary to the authors' claim, many cancer types are not caused by replicative random mutations. Rather than the authors' two arbitrarily individualized groups of cancer, a three-group model is herein proposed in the framework of this technical comment, considerably reducing the fraction of cancer cases hypothetically attributable to random mutations.
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Affiliation(s)
- DOMINIQUE BELPOMME
- Cancer Research Center, Association for Research and Treatments Against Cancer (ARTAC), F-75015 Paris, France
- European Cancer and Environment Research Institute (ECERI), B-1000 Brussels, Belgium
| | - PHILIPPE IRIGARAY
- Cancer Research Center, Association for Research and Treatments Against Cancer (ARTAC), F-75015 Paris, France
- European Cancer and Environment Research Institute (ECERI), B-1000 Brussels, Belgium
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43
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Nakatani Y, Mello CC, Hashimoto SI, Shimada A, Nakamura R, Tsukahara T, Qu W, Yoshimura J, Suzuki Y, Sugano S, Takeda H, Fire A, Morishita S. Associations between nucleosome phasing, sequence asymmetry, and tissue-specific expression in a set of inbred Medaka species. BMC Genomics 2015; 16:978. [PMID: 26584643 PMCID: PMC4653950 DOI: 10.1186/s12864-015-2198-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 11/07/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Transcription start sites (TSSs) with pronounced and phased nucleosome arrays downstream and nucleosome-depleted regions upstream of TSSs are observed in various species. RESULTS We have characterized sequence variation and expression properties of this set of TSSs (which we call "Nucleocyclic TSSs") using germline and somatic cells of three medaka (Oryzias latipes) inbred isolates from different locations. We found nucleocyclic TSSs in medaka to be associated with higher gene expression and characterized by a clear boundary in sequence composition with potentially-nucleosome-destabilizing A/T-enrichment upstream (p < 10(-60)) and nucleosome- accommodating C/G-enrichment downstream (p < 10(-40)) that was highly conserved from an ancestor. A substantial genetic distance between the strains facilitated the in-depth analysis of patterns of fixed mutations, revealing a localization-specific equilibrium between the rates of distinct mutation categories that would serve to maintain the conserved sequence anisotropy around TSSs. Downstream of nucleocyclic TSSs, C to T, T to C, and other mutation rates on the sense strand increased around first nucleosome dyads and decreased around first linkers, which contrasted with genomewide mutational patterns around nucleosomes (p < 5 %). C to T rates are higher than G to A rates around nucleosome associated with germline nucleocyclic TSS sites (p < 5 %), potentially due to the asymmetric effect of transcription-coupled repair. CONCLUSIONS Our results demonstrate an atypical evolutionary process surrounding nucleocyclic TSSs.
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Affiliation(s)
- Yoichiro Nakatani
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-0882, Japan.
| | - Cecilia C Mello
- Department of Pathology, School of Medicine, Stanford University, Stanford, CA, 94305-5324, USA.
| | - Shin-Ichi Hashimoto
- Graduate School of Medical Sciences, Kanazawa University, Kanazawa, 920-1192, Japan.
| | - Atsuko Shimada
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.
| | - Ryohei Nakamura
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.
| | - Tatsuya Tsukahara
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.
| | - Wei Qu
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-0882, Japan.
| | - Jun Yoshimura
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-0882, Japan.
| | - Yutaka Suzuki
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo, 108-8639, Japan.
| | - Sumio Sugano
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo, 108-8639, Japan.
| | - Hiroyuki Takeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.
| | - Andrew Fire
- Departments of Pathology and Genetics, School of Medicine, Stanford University, Stanford, CA, 94305-5324, USA.
| | - Shinichi Morishita
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-0882, Japan.
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44
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Wu X, Hurst LD. Determinants of the Usage of Splice-Associated cis-Motifs Predict the Distribution of Human Pathogenic SNPs. Mol Biol Evol 2015; 33:518-29. [PMID: 26545919 PMCID: PMC4866546 DOI: 10.1093/molbev/msv251] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 10/25/2015] [Indexed: 12/11/2022] Open
Abstract
Where in genes do pathogenic mutations tend to occur and does this provide clues as to the possible underlying mechanisms by which single nucleotide polymorphisms (SNPs) cause disease? As splice-disrupting mutations tend to occur predominantly at exon ends, known also to be hot spots of cis-exonic splice control elements, we examine the relationship between the relative density of such exonic cis-motifs and pathogenic SNPs. In particular, we focus on the intragene distribution of exonic splicing enhancers (ESE) and the covariance between them and disease-associated SNPs. In addition to showing that disease-causing genes tend to be genes with a high intron density, consistent with missplicing, five factors established as trends in ESE usage, are considered: relative position in exons, relative position in genes, flanking intron size, splice sites usage, and phase. We find that more than 76% of pathogenic SNPs are within 3–69 bp of exon ends where ESEs generally reside, this being 13% more than expected. Overall from enrichment of pathogenic SNPs at exon ends, we estimate that approximately 20–45% of SNPs affect splicing. Importantly, we find that within genes pathogenic SNPs tend to occur in splicing-relevant regions with low ESE density: they are found to occur preferentially in the terminal half of genes, in exons flanked by short introns and at the ends of phase (0,0) exons with 3′ non-“AGgt” splice site. We suggest the concept of the “fragile” exon, one home to pathogenic SNPs owing to its vulnerability to splice disruption owing to low ESE density.
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Affiliation(s)
- XianMing Wu
- Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, Somerset, United Kingdom
| | - Laurence D Hurst
- Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, Somerset, United Kingdom
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45
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Chen H, Guan J, Zhou S. DPNuc: Identifying Nucleosome Positions Based on the Dirichlet Process Mixture Model. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2015; 12:1236-1247. [PMID: 26671796 DOI: 10.1109/tcbb.2015.2430350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Nucleosomes and the free linker DNA between them assemble the chromatin. Nucleosome positioning plays an important role in gene transcription regulation, DNA replication and repair, alternative splicing, and so on. With the rapid development of ChIP-seq, it is possible to computationally detect the positions of nucleosomes on chromosomes. However, existing methods cannot provide accurate and detailed information about the detected nucleosomes, especially for the nucleosomes with complex configurations where overlaps and noise exist. Meanwhile, they usually require some prior knowledge of nucleosomes as input, such as the size or the number of the unknown nucleosomes, which may significantly influence the detection results. In this paper, we propose a novel approach DPNuc for identifying nucleosome positions based on the Dirichlet process mixture model. In our method, Markov chain Monte Carlo (MCMC) simulations are employed to determine the mixture model with no need of prior knowledge about nucleosomes. Compared with three existing methods, our approach can provide more detailed information of the detected nucleosomes and can more reasonably reveal the real configurations of the chromosomes; especially, our approach performs better in the complex overlapping situations. By mapping the detected nucleosomes to a synthetic benchmark nucleosome map and two existing benchmark nucleosome maps, it is shown that our approach achieves a better performance in identifying nucleosome positions and gets a higher F-score. Finally, we show that our approach can more reliably detect the size distribution of nucleosomes.
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46
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Chen X, Yang JR, Zhang J. Nascent RNA folding mitigates transcription-associated mutagenesis. Genome Res 2015; 26:50-9. [PMID: 26518484 PMCID: PMC4691750 DOI: 10.1101/gr.195164.115] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 10/14/2015] [Indexed: 11/24/2022]
Abstract
Transcription is mutagenic, in part because the R-loop formed by the binding of the nascent RNA with its DNA template exposes the nontemplate DNA strand to mutagens and primes unscheduled error-prone DNA synthesis. We hypothesize that strong folding of nascent RNA weakens R-loops and hence decreases mutagenesis. By a yeast forward mutation assay, we show that strengthening RNA folding and reducing R-loop formation by synonymous changes in a reporter gene can lower mutation rate by >80%. This effect is diminished after the overexpression of the gene encoding RNase H1 that degrades the RNA in a DNA–RNA hybrid, indicating that the effect is R-loop-dependent. Analysis of genomic data of yeast mutation accumulation lines and human neutral polymorphisms confirms the generality of these findings. This mechanism for local protection of genome integrity is of special importance to highly expressed genes because of their frequent transcription and strong RNA folding, the latter also improves translational fidelity. As a result, strengthening RNA folding simultaneously curtails genotypic and phenotypic mutations.
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Affiliation(s)
- Xiaoshu Chen
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Jian-Rong Yang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
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47
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Beh LY, Müller MM, Muir TW, Kaplan N, Landweber LF. DNA-guided establishment of nucleosome patterns within coding regions of a eukaryotic genome. Genome Res 2015; 25:1727-38. [PMID: 26330564 PMCID: PMC4617968 DOI: 10.1101/gr.188516.114] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 08/20/2015] [Indexed: 12/13/2022]
Abstract
A conserved hallmark of eukaryotic chromatin architecture is the distinctive array of well-positioned nucleosomes downstream from transcription start sites (TSS). Recent studies indicate that trans-acting factors establish this stereotypical array. Here, we present the first genome-wide in vitro and in vivo nucleosome maps for the ciliate Tetrahymena thermophila. In contrast with previous studies in yeast, we find that the stereotypical nucleosome array is preserved in the in vitro reconstituted map, which is governed only by the DNA sequence preferences of nucleosomes. Remarkably, this average in vitro pattern arises from the presence of subsets of nucleosomes, rather than the whole array, in individual Tetrahymena genes. Variation in GC content contributes to the positioning of these sequence-directed nucleosomes and affects codon usage and amino acid composition in genes. Given that the AT-rich Tetrahymena genome is intrinsically unfavorable for nucleosome formation, we propose that these “seed” nucleosomes—together with trans-acting factors—may facilitate the establishment of nucleosome arrays within genes in vivo, while minimizing changes to the underlying coding sequences.
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Affiliation(s)
- Leslie Y Beh
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA
| | - Manuel M Müller
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Tom W Muir
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Noam Kaplan
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Laura F Landweber
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA
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48
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Yazdi PG, Pedersen BA, Taylor JF, Khattab OS, Chen YH, Chen Y, Jacobsen SE, Wang PH. Increasing Nucleosome Occupancy Is Correlated with an Increasing Mutation Rate so Long as DNA Repair Machinery Is Intact. PLoS One 2015; 10:e0136574. [PMID: 26308346 PMCID: PMC4550472 DOI: 10.1371/journal.pone.0136574] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 08/04/2015] [Indexed: 12/30/2022] Open
Abstract
Deciphering the multitude of epigenomic and genomic factors that influence the mutation rate is an area of great interest in modern biology. Recently, chromatin has been shown to play a part in this process. To elucidate this relationship further, we integrated our own ultra-deep sequenced human nucleosomal DNA data set with a host of published human genomic and cancer genomic data sets. Our results revealed, that differences in nucleosome occupancy are associated with changes in base-specific mutation rates. Increasing nucleosome occupancy is associated with an increasing transition to transversion ratio and an increased germline mutation rate within the human genome. Additionally, cancer single nucleotide variants and microindels are enriched within nucleosomes and both the coding and non-coding cancer mutation rate increases with increasing nucleosome occupancy. There is an enrichment of cancer indels at the theoretical start (74 bp) and end (115 bp) of linker DNA between two nucleosomes. We then hypothesized that increasing nucleosome occupancy decreases access to DNA by DNA repair machinery and could account for the increasing mutation rate. Such a relationship should not exist in DNA repair knockouts, and we thus repeated our analysis in DNA repair machinery knockouts to test our hypothesis. Indeed, our results revealed no correlation between increasing nucleosome occupancy and increasing mutation rate in DNA repair knockouts. Our findings emphasize the linkage of the genome and epigenome through the nucleosome whose properties can affect genome evolution and genetic aberrations such as cancer.
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Affiliation(s)
- Puya G. Yazdi
- UC Irvine Diabetes Center, University of California at Irvine, Irvine, California, United States of America
- Sue and Bill Gross Stem Cell Research Center, University of California at Irvine, Irvine, California, United States of America
- Department of Medicine, University of California at Irvine, Irvine, California, United States of America
| | - Brian A. Pedersen
- UC Irvine Diabetes Center, University of California at Irvine, Irvine, California, United States of America
- Sue and Bill Gross Stem Cell Research Center, University of California at Irvine, Irvine, California, United States of America
- Department of Medicine, University of California at Irvine, Irvine, California, United States of America
| | - Jared F. Taylor
- UC Irvine Diabetes Center, University of California at Irvine, Irvine, California, United States of America
- Sue and Bill Gross Stem Cell Research Center, University of California at Irvine, Irvine, California, United States of America
- Department of Medicine, University of California at Irvine, Irvine, California, United States of America
| | - Omar S. Khattab
- UC Irvine Diabetes Center, University of California at Irvine, Irvine, California, United States of America
- Sue and Bill Gross Stem Cell Research Center, University of California at Irvine, Irvine, California, United States of America
| | - Yu-Han Chen
- UC Irvine Diabetes Center, University of California at Irvine, Irvine, California, United States of America
- Sue and Bill Gross Stem Cell Research Center, University of California at Irvine, Irvine, California, United States of America
- Department of Medicine, University of California at Irvine, Irvine, California, United States of America
| | - Yumay Chen
- UC Irvine Diabetes Center, University of California at Irvine, Irvine, California, United States of America
- Sue and Bill Gross Stem Cell Research Center, University of California at Irvine, Irvine, California, United States of America
- Department of Medicine, University of California at Irvine, Irvine, California, United States of America
| | - Steven E. Jacobsen
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, California, United States of America
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California at Los Angeles, Los Angeles, California, United States of America
- Howard Hughes Medical Institute, University of California at Los Angeles, Los Angeles, California, United States of America
| | - Ping H. Wang
- UC Irvine Diabetes Center, University of California at Irvine, Irvine, California, United States of America
- Sue and Bill Gross Stem Cell Research Center, University of California at Irvine, Irvine, California, United States of America
- Department of Medicine, University of California at Irvine, Irvine, California, United States of America
- Department of Biological Chemistry, University of California at Irvine, Irvine, California, United States of America
- Department of Physiology & Biophysics, University of California at Irvine, Irvine, California, United States of America
- * E-mail:
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49
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Yang F, Kemp CJ, Henikoff S. Anthracyclines induce double-strand DNA breaks at active gene promoters. Mutat Res 2015; 773:9-15. [PMID: 25705119 DOI: 10.1016/j.mrfmmm.2015.01.007] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Doxorubicin is a widely used chemotherapeutic drug that intercalates between DNA base-pairs and poisons Topoisomerase II, although the mechanistic basis for cell killing remains speculative. Doxorubicin and related anthracycline compounds have been shown to increase nucleosome turnover and/or eviction around promoters, which suggests that the resulting enhanced exposure of DNA might underlie cell killing. Previously, we showed that low doses of anthracyclines increase nucleosome turnover around active gene promoters, which suggests that loss of nucleosomes might contribute to cancer cell killing. Here we apply a genome-wide method to precisely map DNA double-strand breaks (DSBs) in cancer cells. We find that spontaneous DSBs occur preferentially around promoters of active genes, and that both anthracyclines and etoposide, a Topoisomerase II poison, increase DSBs around promoters, although CpG islands are conspicuously protected from DSBs. We propose that torsion-based enhancement of nucleosome turnover by anthracyclines exposes promoter DNA, ultimately causing DSBs around promoters.
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Makova KD, Hardison RC. The effects of chromatin organization on variation in mutation rates in the genome. Nat Rev Genet 2015; 16:213-23. [PMID: 25732611 PMCID: PMC4500049 DOI: 10.1038/nrg3890] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The variation in local rates of mutations can affect both the evolution of genes and their function in normal and cancer cells. Deciphering the molecular determinants of this variation will be aided by the elucidation of distinct types of mutations, as they differ in regional preferences and in associations with genomic features. Chromatin organization contributes to regional variation in mutation rates, but its contribution differs among mutation types. In both germline and somatic mutations, base substitutions are more abundant in regions of closed chromatin, perhaps reflecting error accumulation late in replication. By contrast, a distinctive mutational state with very high levels of insertions and deletions (indels) and substitutions is enriched in regions of open chromatin. These associations indicate an intricate interplay between the nucleotide sequence of DNA and its dynamic packaging into chromatin, and have important implications for current biomedical research. This Review focuses on recent studies showing associations between chromatin state and mutation rates, including pairwise and multivariate investigations of germline and somatic (particularly cancer) mutations.
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Affiliation(s)
- Kateryna D Makova
- Department of Biology, Huck Institute for Genome Sciences, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, USA
| | - Ross C Hardison
- Department of Biochemistry and Molecular Biology, Huck Institute for Genome Sciences, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, USA
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