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Zheng Y, Keleş S. FreeHi-C simulates high-fidelity Hi-C data for benchmarking and data augmentation. Nat Methods 2020; 17:37-40. [PMID: 31712779 PMCID: PMC8136837 DOI: 10.1038/s41592-019-0624-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 09/26/2019] [Indexed: 02/06/2023]
Abstract
The ability to simulate high-throughput chromatin conformation (Hi-C) data is foundational for benchmarking Hi-C data analysis methods. Here we present a nonparametric strategy named FreeHi-C to simulate Hi-C data from the interacting genome fragments. Data from FreeHi-C exhibit high fidelity to biological Hi-C data. FreeHi-C boosts the precision and power of differential chromatin interaction detection through data augmentation under preserved false discovery rate control.
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Affiliation(s)
- Ye Zheng
- Department of Statistics, University of Wisconsin-Madison, Madison, WI, USA
| | - Sündüz Keleş
- Department of Statistics, University of Wisconsin-Madison, Madison, WI, USA.
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI, USA.
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52
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Abstract
BACKGROUND Topologically associating domains (TADs) are genomic regions with varying lengths. The interactions within TADs are more frequent than those between different TADs. TADs or sub-TADs are considered the structural and functional units of the mammalian genomes. Although TADs are important for understanding how genomes function, we have limited knowledge about their 3D structural properties. RESULTS In this study, we designed and benchmarked three metrics for capturing the three-dimensional and two-dimensional structural signatures of TADs, which can help better understand TADs' structural properties and the relationships between structural properties and genetic and epigenetic features. The first metric for capturing 3D structural properties is radius of gyration, which in this study is used to measure the spatial compactness of TADs. The mass value of each DNA bead in a 3D structure is novelly defined as one or more genetic or epigenetic feature(s). The second metric is folding degree. The last metric is exponent parameter, which is used to capture the 2D structural properties based on TADs' Hi-C contact matrices. In general, we observed significant correlations between the three metrics and the genetic and epigenetic features. We made the same observations when using H3K4me3, transcription start sites, and RNA polymerase II to represent the mass value in the modified radius-of-gyration metric. Moreover, we have found that the TADs in the clusters of depleted chromatin states apparently correspond to smaller exponent parameters and larger radius of gyrations. In addition, a new objective function of multidimensional scaling for modelling chromatin or TADs 3D structures was designed and benchmarked, which can handle the DNA bead-pairs with zero Hi-C contact values. CONCLUSIONS The web server for reconstructing chromatin 3D structures using multiple different objective functions and the related source code are publicly available at http://dna.cs.miami.edu/3DChrom/.
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Affiliation(s)
- Tong Liu
- Department of Computer Science, University of Miami, 1365 Memorial Drive, P.O. Box 248154, Coral Gables, FL 33124 USA
| | - Zheng Wang
- Department of Computer Science, University of Miami, 1365 Memorial Drive, P.O. Box 248154, Coral Gables, FL 33124 USA
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53
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Ben-Elazar S, Chor B, Yakhini Z. The Functional 3D Organization of Unicellular Genomes. Sci Rep 2019; 9:12734. [PMID: 31484964 PMCID: PMC6726614 DOI: 10.1038/s41598-019-48798-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/12/2019] [Indexed: 11/09/2022] Open
Abstract
Genome conformation capture techniques permit a systematic investigation into the functional spatial organization of genomes, including functional aspects like assessing the co-localization of sets of genomic elements. For example, the co-localization of genes targeted by a transcription factor (TF) within a transcription factory. We quantify spatial co-localization using a rigorous statistical model that measures the enrichment of a subset of elements in neighbourhoods inferred from Hi-C data. We also control for co-localization that can be attributed to genomic order. We systematically apply our open-sourced framework, spatial-mHG, to search for spatial co-localization phenomena in multiple unicellular Hi-C datasets with corresponding genomic annotations. Our biological findings shed new light on the functional spatial organization of genomes, including: In C. crescentus, DNA replication genes reside in two genomic clusters that are spatially co-localized. Furthermore, these clusters contain similar gene copies and lay in genomic vicinity to the ori and ter sequences. In S. cerevisae, Ty5 retrotransposon family element spatially co-localize at a spatially adjacent subset of telomeres. In N. crassa, both Proteasome lid subcomplex genes and protein refolding genes jointly spatially co-localize at a shared location. An implementation of our algorithms is available online.
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54
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Ku C, Sebé-Pedrós A. Using single-cell transcriptomics to understand functional states and interactions in microbial eukaryotes. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190098. [PMID: 31587645 PMCID: PMC6792447 DOI: 10.1098/rstb.2019.0098] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2019] [Indexed: 12/13/2022] Open
Abstract
Understanding the diversity and evolution of eukaryotic microorganisms remains one of the major challenges of modern biology. In recent years, we have advanced in the discovery and phylogenetic placement of new eukaryotic species and lineages, which in turn completely transformed our view on the eukaryotic tree of life. But we remain ignorant of the life cycles, physiology and cellular states of most of these microbial eukaryotes, as well as of their interactions with other organisms. Here, we discuss how high-throughput genome-wide gene expression analysis of eukaryotic single cells can shed light on protist biology. First, we review different single-cell transcriptomics methodologies with particular focus on microbial eukaryote applications. Then, we discuss single-cell gene expression analysis of protists in culture and what can be learnt from these approaches. Finally, we envision the application of single-cell transcriptomics to protist communities to interrogate not only community components, but also the gene expression signatures of distinct cellular and physiological states, as well as the transcriptional dynamics of interspecific interactions. Overall, we argue that single-cell transcriptomics can significantly contribute to our understanding of the biology of microbial eukaryotes. This article is part of a discussion meeting issue 'Single cell ecology'.
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Affiliation(s)
- Chuan Ku
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Arnau Sebé-Pedrós
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona 08003, Spain
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55
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Lenz T, Le Roch KG. Three-Dimensional Genome Organization and Virulence in Apicomplexan Parasites. Epigenet Insights 2019; 12:2516865719879436. [PMID: 31633082 PMCID: PMC6769224 DOI: 10.1177/2516865719879436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 09/06/2019] [Indexed: 12/19/2022] Open
Abstract
Mounting evidence supports the idea that epigenetic, and the overall 3-dimensional (3D) architecture of the genome, plays an important role in gene expression for eukaryotic organisms. We recently used Hi-C methodologies to generate and compare the 3D genome of 7 different apicomplexan parasites, including several pathogenic and less pathogenic malaria parasites as well as related human parasites Babesia microti and Toxoplasma gondii. Our goal was to understand the possible relationship between genome organization, gene expression, and pathogenicity of these infectious agents. Collectively, our results demonstrate that spatial genome organization in most Plasmodium species is constrained by the colocalization of virulence genes that are unique in their effect on chromosome folding, indicating a link between genome organization and gene expression in more virulent pathogens.
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Affiliation(s)
- Todd Lenz
- Department of Molecular, Cell and Systems Biology (MCSB), University of California, Riverside, Riverside, CA, USA
| | - Karine G Le Roch
- Department of Molecular, Cell and Systems Biology (MCSB), University of California, Riverside, Riverside, CA, USA
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56
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Ing-Simmons E, Vaquerizas JM. Visualising three-dimensional genome organisation in two dimensions. Development 2019; 146:146/19/dev177162. [PMID: 31558569 DOI: 10.1242/dev.177162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The three-dimensional organisation of the genome plays a crucial role in developmental gene regulation. In recent years, techniques to investigate this organisation have become more accessible to labs worldwide due to improvements in protocols and decreases in the cost of high-throughput sequencing. However, the resulting datasets are complex and can be challenging to analyse and interpret. Here, we provide a guide to visualisation approaches that can aid the interpretation of such datasets and the communication of biological results.
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Affiliation(s)
- Elizabeth Ing-Simmons
- Max Planck Institute for Molecular Biomedicine, Roentgenstrasse 20, DE-48149 Muenster, Germany
| | - Juan M Vaquerizas
- Max Planck Institute for Molecular Biomedicine, Roentgenstrasse 20, DE-48149 Muenster, Germany
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57
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Yu X, Martin PGP, Michaels SD. BORDER proteins protect expression of neighboring genes by promoting 3' Pol II pausing in plants. Nat Commun 2019; 10:4359. [PMID: 31554790 PMCID: PMC6761125 DOI: 10.1038/s41467-019-12328-w] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 08/30/2019] [Indexed: 12/18/2022] Open
Abstract
Ensuring that one gene's transcription does not inappropriately affect the expression of its neighbors is a fundamental challenge to gene regulation in a genomic context. In plants, which lack homologs of animal insulator proteins, the mechanisms that prevent transcriptional interference are not well understood. Here we show that BORDER proteins are enriched in intergenic regions and prevent interference between closely spaced genes on the same strand by promoting the 3' pausing of RNA polymerase II at the upstream gene. In the absence of BORDER proteins, 3' pausing associated with the upstream gene is reduced and shifts into the promoter region of the downstream gene. This is consistent with a model in which BORDER proteins inhibit transcriptional interference by preventing RNA polymerase from intruding into the promoters of downstream genes.
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Affiliation(s)
- Xuhong Yu
- Department of Biology, Indiana University, 915 East Third Street, Bloomington, IN, 47405, USA
| | - Pascal G P Martin
- Department of Biology, Indiana University, 915 East Third Street, Bloomington, IN, 47405, USA.,Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRA, ENVT, INP-Purpan, UPS, 31027, Toulouse, France
| | - Scott D Michaels
- Department of Biology, Indiana University, 915 East Third Street, Bloomington, IN, 47405, USA.
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58
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Abel S, Le Roch KG. The role of epigenetics and chromatin structure in transcriptional regulation in malaria parasites. Brief Funct Genomics 2019; 18:302-313. [PMID: 31220857 PMCID: PMC6859822 DOI: 10.1093/bfgp/elz005] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 02/25/2019] [Accepted: 03/14/2019] [Indexed: 12/28/2022] Open
Abstract
Due to the unique selective pressures and extreme changes faced by the human malaria parasite Plasmodium falciparum throughout its life cycle, the parasite has evolved distinct features to alter its gene expression patterns. Along with classical gene regulation by transcription factors (TFs), of which only one family, the AP2 TFs, has been described in the parasite genome, a large body of evidence points toward chromatin structure and epigenetic factors mediating the changes in gene expression associated with parasite life cycle stages. These attributes may be critically important for immune evasion, host cell invasion and development of the parasite in its two hosts, the human and the Anopheles vector. Thus, the factors involved in the maintenance and regulation of chromatin and epigenetic features represent potential targets for antimalarial drugs. In this review, we discuss the mechanisms in P. falciparum that regulate chromatin structure, nucleosome landscape, the 3-dimensional structure of the genome and additional distinctive features created by parasite-specific genes and gene families. We review conserved traits of chromatin in eukaryotes in order to highlight what is unique in the parasite.
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Affiliation(s)
- Steven Abel
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA, USA
| | - Karine G Le Roch
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA, USA
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59
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Briand N, Collas P. Laminopathy-causing lamin A mutations reconfigure lamina-associated domains and local spatial chromatin conformation. Nucleus 2019. [PMID: 29517398 PMCID: PMC5973257 DOI: 10.1080/19491034.2018.1449498] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The nuclear lamina contributes to the regulation of gene expression and to chromatin organization. Mutations in A-type nuclear lamins cause laminopathies, some of which are associated with a loss of heterochromatin at the nuclear periphery. Until recently however, little if any information has been provided on where and how lamin A interacts with the genome and on how disease-causing lamin A mutations may rearrange genome conformation. Here, we review aspects of nuclear lamin association with the genome. We highlight recent evidence of reorganization of lamin A-chromatin interactions in cellular models of laminopathies, and implications on the 3-dimensional rearrangement of chromatin in these models, including patient cells. We discuss how a hot-spot lipodystrophic lamin A mutation alters chromatin conformation and epigenetic patterns at an anti-adipogenic locus, and conclude with remarks on links between lamin A, Polycomb and the pathophysiology of laminopathies. The recent findings presented here collectively argue towards a deregulation of large-scale and local spatial genome organization by a subset of lamin A mutations causing laminopathies.
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Affiliation(s)
- Nolwenn Briand
- a Department of Molecular Medicine , Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo , Oslo , Norway
| | - Philippe Collas
- a Department of Molecular Medicine , Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo , Oslo , Norway.,b Norwegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine , Oslo University Hospital , Oslo , Norway
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60
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Read DF, Cook K, Lu YY, Le Roch KG, Noble WS. Predicting gene expression in the human malaria parasite Plasmodium falciparum using histone modification, nucleosome positioning, and 3D localization features. PLoS Comput Biol 2019; 15:e1007329. [PMID: 31509524 PMCID: PMC6756558 DOI: 10.1371/journal.pcbi.1007329] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 09/23/2019] [Accepted: 08/12/2019] [Indexed: 12/02/2022] Open
Abstract
Empirical evidence suggests that the malaria parasite Plasmodium falciparum employs a broad range of mechanisms to regulate gene transcription throughout the organism's complex life cycle. To better understand this regulatory machinery, we assembled a rich collection of genomic and epigenomic data sets, including information about transcription factor (TF) binding motifs, patterns of covalent histone modifications, nucleosome occupancy, GC content, and global 3D genome architecture. We used these data to train machine learning models to discriminate between high-expression and low-expression genes, focusing on three distinct stages of the red blood cell phase of the Plasmodium life cycle. Our results highlight the importance of histone modifications and 3D chromatin architecture in Plasmodium transcriptional regulation and suggest that AP2 transcription factors may play a limited regulatory role, perhaps operating in conjunction with epigenetic factors.
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Affiliation(s)
- David F. Read
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Kate Cook
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Yang Y. Lu
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Karine G. Le Roch
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, California, United States of America
| | - William Stafford Noble
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
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61
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The Impact of Centromeres on Spatial Genome Architecture. Trends Genet 2019; 35:565-578. [PMID: 31200946 DOI: 10.1016/j.tig.2019.05.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/06/2019] [Accepted: 05/09/2019] [Indexed: 01/01/2023]
Abstract
The development of new technologies and experimental techniques is enabling researchers to see what was once unable to be seen. For example, the centromere was first seen as the mediator between spindle fiber and chromosome during mitosis and meiosis. Although this continues to be its most prominent role, we now know that the centromere functions beyond cellular division with important roles in genome organization and chromatin regulation. Here we aim to share the structures and functions of centromeres in various organisms beginning with the diversity of their DNA sequence anatomies. We zoom out to describe their position in the nucleus and ultimately detail the different ways they contribute to genome organization and regulation at the spatial level.
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62
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Abbas A, He X, Niu J, Zhou B, Zhu G, Ma T, Song J, Gao J, Zhang MQ, Zeng J. Integrating Hi-C and FISH data for modeling of the 3D organization of chromosomes. Nat Commun 2019; 10:2049. [PMID: 31053705 PMCID: PMC6499832 DOI: 10.1038/s41467-019-10005-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 04/12/2019] [Indexed: 12/13/2022] Open
Abstract
The new advances in various experimental techniques that provide complementary information about the spatial conformations of chromosomes have inspired researchers to develop computational methods to fully exploit the merits of individual data sources and combine them to improve the modeling of chromosome structure. Here we propose GEM-FISH, a method for reconstructing the 3D models of chromosomes through systematically integrating both Hi-C and FISH data with the prior biophysical knowledge of a polymer model. Comprehensive tests on a set of chromosomes, for which both Hi-C and FISH data are available, demonstrate that GEM-FISH can outperform previous chromosome structure modeling methods and accurately capture the higher order spatial features of chromosome conformations. Moreover, our reconstructed 3D models of chromosomes revealed interesting patterns of spatial distributions of super-enhancers which can provide useful insights into understanding the functional roles of these super-enhancers in gene regulation.
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Affiliation(s)
- Ahmed Abbas
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, China
| | - Xuan He
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, China
| | - Jing Niu
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Bin Zhou
- School of Life Science, Tsinghua University, Beijing, 100084, China
| | - Guangxiang Zhu
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, China
| | - Tszshan Ma
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Jiangpeikun Song
- School of Life Science, Tsinghua University, Beijing, 100084, China
| | - Juntao Gao
- MOE Key Laboratory of Bioinformatics; Bioinformatics Division, Center for Synthetic and Systems Biology, BNRist; Department of Automation, Tsinghua University; Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China
| | - Michael Q Zhang
- Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
- MOE Key Laboratory of Bioinformatics; Bioinformatics Division, Center for Synthetic and Systems Biology, BNRist; Department of Automation, Tsinghua University; Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China
- Department of Biological Sciences, Center for Systems Biology, the University of Texas at Dallas, Richardson, TX, 75080-3021, USA
| | - Jianyang Zeng
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, 100084, China.
- MOE Key Laboratory of Bioinformatics; Bioinformatics Division, Center for Synthetic and Systems Biology, BNRist; Department of Automation, Tsinghua University; Center for Synthetic and Systems Biology, Tsinghua University, Beijing, 100084, China.
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63
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Oluwadare O, Highsmith M, Cheng J. An Overview of Methods for Reconstructing 3-D Chromosome and Genome Structures from Hi-C Data. Biol Proced Online 2019; 21:7. [PMID: 31049033 PMCID: PMC6482566 DOI: 10.1186/s12575-019-0094-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/01/2019] [Indexed: 01/08/2023] Open
Abstract
Over the past decade, methods for predicting three-dimensional (3-D) chromosome and genome structures have proliferated. This has been primarily due to the development of high-throughput, next-generation chromosome conformation capture (3C) technologies, which have provided next-generation sequencing data about chromosome conformations in order to map the 3-D genome structure. The introduction of the Hi-C technique-a variant of the 3C method-has allowed researchers to extract the interaction frequency (IF) for all loci of a genome at high-throughput and at a genome-wide scale. In this review we describe, categorize, and compare the various methods developed to map chromosome and genome structures from 3C data-particularly Hi-C data. We summarize the improvements introduced by these methods, describe the approach used for method evaluation, and discuss how these advancements shape the future of genome structure construction.
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Affiliation(s)
- Oluwatosin Oluwadare
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO 65211 USA
| | - Max Highsmith
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO 65211 USA
| | - Jianlin Cheng
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO 65211 USA
- Informatics Institute, University of Missouri, Columbia, MO 65211 USA
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64
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Szabo Q, Bantignies F, Cavalli G. Principles of genome folding into topologically associating domains. SCIENCE ADVANCES 2019; 5:eaaw1668. [PMID: 30989119 PMCID: PMC6457944 DOI: 10.1126/sciadv.aaw1668] [Citation(s) in RCA: 323] [Impact Index Per Article: 64.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 02/20/2019] [Indexed: 05/12/2023]
Abstract
This review discusses the features of TADs across species, and their role in chromosome organization, genome function, and evolution.
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Affiliation(s)
- Quentin Szabo
- Institute of Human Genetics, CNRS and University of Montpellier, Montpellier, France
| | - Frédéric Bantignies
- Institute of Human Genetics, CNRS and University of Montpellier, Montpellier, France
| | - Giacomo Cavalli
- Institute of Human Genetics, CNRS and University of Montpellier, Montpellier, France
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65
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Abstract
BACKGROUND Recent advances in genome analysis have established that chromatin has preferred 3D conformations, which bring distant loci into contact. Identifying these contacts is important for us to understand possible interactions between these loci. This has motivated the creation of the Hi-C technology, which detects long-range chromosomal interactions. Distance geometry-based algorithms, such as ChromSDE and ShRec3D, have been able to utilize Hi-C data to infer 3D chromosomal structures. However, these algorithms, being matrix-based, are space- and time-consuming on very large datasets. A human genome of 100 kilobase resolution would involve ∼30,000 loci, requiring gigabytes just in storing the matrices. RESULTS We propose a succinct representation of the distance matrices which tremendously reduces the space requirement. We give a complete solution, called SuperRec, for the inference of chromosomal structures from Hi-C data, through iterative solving the large-scale weighted multidimensional scaling problem. CONCLUSIONS SuperRec runs faster than earlier systems without compromising on result accuracy. The SuperRec package can be obtained from http://www.cs.cityu.edu.hk/~shuaicli/SuperRec .
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Affiliation(s)
- Yanlin Zhang
- Department of Computer Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR
| | - Weiwei Liu
- Department of Computer Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR
| | - Yu Lin
- Research School of Computer Science, the Australian National University, Canberra, Australia
| | - Yen Kaow Ng
- Department of Computer Science, Faculty of Information and Communication Technology, Universiti Tunku Abdul Rahman, Kampar, Malaysia
| | - Shuaicheng Li
- Department of Computer Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong SAR
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66
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DNA helicase RecQ1 regulates mutually exclusive expression of virulence genes in Plasmodium falciparum via heterochromatin alteration. Proc Natl Acad Sci U S A 2019; 116:3177-3182. [PMID: 30728298 DOI: 10.1073/pnas.1811766116] [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: 11/18/2022] Open
Abstract
The Plasmodium falciparum var gene family encodes ∼60 surface antigens by which parasites escape the host immune responses via clonal expression of var genes. However, the mechanism controlling this mutual exclusivity, associated with alterations in chromatin assembly, is not understood. Here, we determined how expression of the var gene family is regulated by two RecQ DNA helicase family members, PfRecQ1 and PfWRN, in P. falciparum Through genetic manipulation, we found that the complete var repertoire was silenced on PfRecQ1 knockout, whereas their expression did not show noticeable changes when PfWRN was knocked out. More important, mutually exclusive expression of var genes could be rescued by complementation of PfRecQ1. In addition, knocking out either of these two helicase genes changed the perinuclear cluster distribution of subtelomeres and subtelomeric var genes. Whereas deletion of PfRecQ1 increased the heterochromatin mark trimethylated (H3K9me3) at the transcription start site (TSS) of the var gene upsC1, that deletion had no effect on the global distribution of H3K9me3 over gene bodies, including those for the var genes. ChIP-seq assay showed that PfRecQ1 was enriched globally at the TSSs of all genes, whereas PfWRN-enriched regions occurred at the gene bodies of the var gene family, but not of other genes or at TSSs of all genes. On PfRecQ1 deletion, the upsC1 var gene moved from the active perinuclear transcription region to a silenced region of the upsC type. These findings imply that PfRecQ1, but not PfWRN, is essential for maintaining the clonal expression of var genes.
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67
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Abstract
The positioning of chromosomes in the nucleus of a eukaryotic cell is highly organized and has a complex and dynamic relationship with gene expression. In the human malaria parasite Plasmodium falciparum, the clustering of a family of virulence genes correlates with their coordinated silencing and has a strong influence on the overall organization of the genome. To identify conserved and species-specific principles of genome organization, we performed Hi-C experiments and generated 3D genome models for five Plasmodium species and two related apicomplexan parasites. Plasmodium species mainly showed clustering of centromeres, telomeres, and virulence genes. In P. falciparum, the heterochromatic virulence gene cluster had a strong repressive effect on the surrounding nuclear space, while this was less pronounced in Plasmodium vivax and Plasmodium berghei, and absent in Plasmodium yoelii In Plasmodium knowlesi, telomeres and virulence genes were more dispersed throughout the nucleus, but its 3D genome showed a strong correlation with gene expression. The Babesia microti genome showed a classical Rabl organization with colocalization of subtelomeric virulence genes, while the Toxoplasma gondii genome was dominated by clustering of the centromeres and lacked virulence gene clustering. Collectively, our results demonstrate that spatial genome organization in most Plasmodium species is constrained by the colocalization of virulence genes. P. falciparum and P. knowlesi, the only two Plasmodium species with gene families involved in antigenic variation, are unique in the effect of these genes on chromosome folding, indicating a potential link between genome organization and gene expression in more virulent pathogens.
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68
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Zheng Y, Ay F, Keles S. Generative modeling of multi-mapping reads with mHi-C advances analysis of Hi-C studies. eLife 2019; 8:e38070. [PMID: 30702424 PMCID: PMC6450682 DOI: 10.7554/elife.38070] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 01/30/2019] [Indexed: 12/18/2022] Open
Abstract
Current Hi-C analysis approaches are unable to account for reads that align to multiple locations, and hence underestimate biological signal from repetitive regions of genomes. We developed and validated mHi-C, a multi-read mapping strategy to probabilistically allocate Hi-C multi-reads. mHi-C exhibited superior performance over utilizing only uni-reads and heuristic approaches aimed at rescuing multi-reads on benchmarks. Specifically, mHi-C increased the sequencing depth by an average of 20% resulting in higher reproducibility of contact matrices and detected interactions across biological replicates. The impact of the multi-reads on the detection of significant interactions is influenced marginally by the relative contribution of multi-reads to the sequencing depth compared to uni-reads, cis-to-trans ratio of contacts, and the broad data quality as reflected by the proportion of mappable reads of datasets. Computational experiments highlighted that in Hi-C studies with short read lengths, mHi-C rescued multi-reads can emulate the effect of longer reads. mHi-C also revealed biologically supported bona fide promoter-enhancer interactions and topologically associating domains involving repetitive genomic regions, thereby unlocking a previously masked portion of the genome for conformation capture studies.
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Affiliation(s)
- Ye Zheng
- Department of StatisticsUniversity of Wisconsin-MadisonMadisonUnited States
| | - Ferhat Ay
- La Jolla Institute for Allergy and ImmunologyLa JollaUnited States
- School of MedicineUniversity of California, San DiegoLa JollaUnited States
| | - Sunduz Keles
- Department of StatisticsUniversity of Wisconsin-MadisonMadisonUnited States
- Department of Biostatistics and Medical InformaticsUniversity of Wisconsin-MadisonMadisonUnited States
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69
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Ararat-Sarria M, Patarroyo MA, Curtidor H. Parasite-Related Genetic and Epigenetic Aspects and Host Factors Influencing Plasmodium falciparum Invasion of Erythrocytes. Front Cell Infect Microbiol 2019; 8:454. [PMID: 30693273 PMCID: PMC6339890 DOI: 10.3389/fcimb.2018.00454] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Accepted: 12/21/2018] [Indexed: 01/13/2023] Open
Abstract
Malaria, a disease caused by Plasmodium parasites, is widespread throughout tropical and sub-tropical regions worldwide; it mostly affects children and pregnant woman. Eradication has stalled despite effective prevention measures and medication being available for this disease; this has mainly been due to the parasite's resistance to medical treatment and the mosquito vector's resistance to insecticides. Tackling such resistance involves using renewed approaches and techniques for accruing a deep understanding of the parasite's biology, and developing new drugs and vaccines. Studying the parasite's invasion of erythrocytes should shed light on its ability to switch between invasion phenotypes related to the expression of gene sets encoding proteins acting as ligands during target cell invasion, thereby conferring mechanisms for evading a particular host's immune response and adapting to changes in target cell surface receptors. This review considers some factors influencing the expression of such phenotypes, such as Plasmodium's genetic, transcriptional and epigenetic characteristics, and explores some host-related aspects which could affect parasite phenotypes, aiming at integrating knowledge regarding this topic and the possible relationship between the parasite's biology and host factors playing a role in erythrocyte invasion.
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Affiliation(s)
- Monica Ararat-Sarria
- Receptor-Ligand Department, Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,PhD Programme in Biomedical and Biological Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Manuel A Patarroyo
- Molecular Biology and Immunology Department, Fundación Instituto de Immunología de Colombia (FIDIC), Bogotá, Colombia.,School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Hernando Curtidor
- Receptor-Ligand Department, Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
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70
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Vaschetto LM, Ortiz N. The Role of Sequence Duplication in Transcriptional Regulation and Genome Evolution. Curr Genomics 2019; 20:405-408. [PMID: 32476997 PMCID: PMC7235390 DOI: 10.2174/1389202920666190320140721] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 01/22/2019] [Accepted: 01/24/2019] [Indexed: 12/26/2022] Open
Abstract
Sequence duplication is nowadays recognized as an important mechanism that underlies the evolution of eukaryote genomes, being indeed one of the most powerful strategies for the generation of adaptive diversity by modulating transcriptional activity. The evolutionary novelties simultaneously associated with sequence duplication and differential gene expression can be collectively referred to as duplication-mediated transcriptional regulation. In the last years, evidence has emerged supporting the idea that sequence duplication and functionalization represent important evolutionary strategies acting at the genome level, and both coding and non-coding sequences have been found to be targets of such events. Moreover, it has been proposed that deleterious effects of sequence duplication might be potentially silenced by endogenous cell machinery (i.e., RNA interference, epigenetic repressive marks, etc). Along these lines, our aim is to highlight the role of sequence duplication on transcriptional activity and the importance of both in genome evolution.
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Affiliation(s)
- Luis M Vaschetto
- Instituto de Diversidad y Ecología Animal, Consejo Nacional de Investigaciones Científicas y Técnicas (IDEA, CONICET), Av. Vélez Sarsfield 299, X5000JJC Córdoba, Argentina.,Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, (FCEFyN, UNC), Av. Vélez Sarsfield 299, X5000JJC Córdoba, Argentina
| | - Natalia Ortiz
- Instituto de Diversidad y Ecología Animal, Consejo Nacional de Investigaciones Científicas y Técnicas (IDEA, CONICET), Av. Vélez Sarsfield 299, X5000JJC Córdoba, Argentina.,Cátedra de Genética de Poblaciones y Evolución, Facultad de Ciencias Exactas, Físicas y Naturales, UNC, Córdoba, Argentina
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71
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Ohno M, Ando T, Priest DG, Kumar V, Yoshida Y, Taniguchi Y. Sub-nucleosomal Genome Structure Reveals Distinct Nucleosome Folding Motifs. Cell 2019; 176:520-534.e25. [DOI: 10.1016/j.cell.2018.12.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 10/16/2018] [Accepted: 12/09/2018] [Indexed: 12/11/2022]
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72
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Liu T, Wang Z. Reconstructing high-resolution chromosome three-dimensional structures by Hi-C complex networks. BMC Bioinformatics 2018; 19:496. [PMID: 30591009 PMCID: PMC6309071 DOI: 10.1186/s12859-018-2464-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Hi-C data have been widely used to reconstruct chromosomal three-dimensional (3D) structures. One of the key limitations of Hi-C is the unclear relationship between spatial distance and the number of Hi-C contacts. Many methods used a fixed parameter when converting the number of Hi-C contacts to wish distances. However, a single parameter cannot properly explain the relationship between wish distances and genomic distances or the locations of topologically associating domains (TADs). RESULTS We have addressed one of the key issues of using Hi-C data, that is, the unclear relationship between spatial distances and the number of Hi-C contacts, which is crucial to understand significant biological functions, such as the enhancer-promoter interactions. Specifically, we developed a new method to infer this converting parameter and pairwise Euclidean distances based on the topology of the Hi-C complex network (HiCNet). The inferred distances were modeled by clustering coefficient and multiple other types of constraints. We found that our inferred distances between bead-pairs within the same TAD were apparently smaller than those distances between bead-pairs from different TADs. Our inferred distances had a higher correlation with fluorescence in situ hybridization (FISH) data, fitted the localization patterns of Xist transcripts on DNA, and better matched 156 pairs of protein-enabled long-range chromatin interactions detected by ChIA-PET. Using the inferred distances and another round of optimization, we further reconstructed 40 kb high-resolution 3D chromosomal structures of mouse male ES cells. The high-resolution structures successfully illustrate TADs and DNA loops (peaks in Hi-C contact heatmaps) that usually indicate enhancer-promoter interactions. CONCLUSIONS We developed a novel method to infer the wish distances between DNA bead-pairs from Hi-C contacts. High-resolution 3D structures of chromosomes were built based on the newly-inferred wish distances. This whole process has been implemented as a tool named HiCNet, which is publicly available at http://dna.cs.miami.edu/HiCNet/ .
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Affiliation(s)
- Tong Liu
- Department of Computer Science, University of Miami, 1365 Memorial Drive, Coral Gables, FL, 33124, USA
| | - Zheng Wang
- Department of Computer Science, University of Miami, 1365 Memorial Drive, Coral Gables, FL, 33124, USA.
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73
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Zhu L, Tripathi J, Rocamora FM, Miotto O, van der Pluijm R, Voss TS, Mok S, Kwiatkowski DP, Nosten F, Day NPJ, White NJ, Dondorp AM, Bozdech Z. The origins of malaria artemisinin resistance defined by a genetic and transcriptomic background. Nat Commun 2018; 9:5158. [PMID: 30514877 PMCID: PMC6279830 DOI: 10.1038/s41467-018-07588-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 11/02/2018] [Indexed: 12/18/2022] Open
Abstract
The predisposition of parasites acquiring artemisinin resistance still remains unclear beyond the mutations in Pfk13 gene and modulation of the unfolded protein response pathway. To explore the chain of casualty underlying artemisinin resistance, we reanalyze 773 P. falciparum isolates from TRACI-study integrating TWAS, GWAS, and eQTL analyses. We find the majority of P. falciparum parasites are transcriptomically converged within each geographic site with two broader physiological profiles across the Greater Mekong Subregion (GMS). We report 8720 SNP-expression linkages in the eastern GMS parasites and 4537 in the western. The minimal overlap between them suggests differential gene regulatory networks facilitating parasite adaptations to their unique host environments. Finally, we identify two genetic and physiological backgrounds associating with artemisinin resistance in the GMS, together with a farnesyltransferase protein and a thioredoxin-like protein which may act as vital intermediators linking the Pfk13 C580Y mutation to the prolonged parasite clearance time.
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Affiliation(s)
- Lei Zhu
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - Jaishree Tripathi
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | | | - Olivo Miotto
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research, University of Oxford, Oxford, OX3 7LF, UK
- Medical Research Council (MRC) Centre for Genomics and Global Health, University of Oxford, Oxford, OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK
| | - Rob van der Pluijm
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research, University of Oxford, Oxford, OX3 7LF, UK
| | - Till S Voss
- Swiss Tropical and Public Health Institute, Basel, 4051, Switzerland
- University of Basel, Basel, 4001, Switzerland
| | - Sachel Mok
- Columbia University Medical Center, Columbia University, New York, 10027, USA
| | - Dominic P Kwiatkowski
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research, University of Oxford, Oxford, OX3 7LF, UK
- Medical Research Council (MRC) Centre for Genomics and Global Health, University of Oxford, Oxford, OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK
| | - François Nosten
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, 63110, Thailand
| | - Nicholas P J Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research, University of Oxford, Oxford, OX3 7LF, UK
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research, University of Oxford, Oxford, OX3 7LF, UK
| | - Arjen M Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research, University of Oxford, Oxford, OX3 7LF, UK
| | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore.
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74
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Yu S, Zheng C, Zhou F, Baillie DL, Rose AM, Deng Z, Chu JSC. Genomic identification and functional analysis of essential genes in Caenorhabditis elegans. BMC Genomics 2018; 19:871. [PMID: 30514206 PMCID: PMC6278001 DOI: 10.1186/s12864-018-5251-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 11/14/2018] [Indexed: 11/27/2022] Open
Abstract
Background Essential genes are required for an organism’s viability and their functions can vary greatly, spreading across many pathways. Due to the importance of essential genes, large scale efforts have been undertaken to identify the complete set of essential genes and to understand their function. Studies of genome architecture and organization have found that genes are not randomly disturbed in the genome. Results Using combined genetic mapping, Illumina sequencing, and bioinformatics analyses, we successfully identified 44 essential genes with 130 lethal mutations in genomic regions of C. elegans of around 7.3 Mb from Chromosome I (left). Of the 44 essential genes, six of which were genes not characterized previously by mutant alleles, let-633/let-638 (B0261.1), let-128 (C53H9.2), let-511 (W09C3.4), let-162 (Y47G6A.18), let-510 (Y47G6A.19), and let-131 (Y71G12B.6). Examine essential genes with Hi-C data shows that essential genes tend to cluster within TAD units rather near TAD boundaries. We have also shown that essential genes in the left half of chromosome I in C. elegans function in enzyme and nucleic acid binding activities during fundamental processes, such as DNA replication, transcription, and translation. From protein-protein interaction networks, essential genes exhibit more protein connectivity than non-essential genes in the genome. Also, many of the essential genes show strong expression in embryos or early larvae stages, indicating that they are important to early development. Conclusions Our results confirmed that this work provided a more comprehensive picture of the essential gene and their functional characterization. These genetic resources will offer important tools for further heath and disease research. Electronic supplementary material The online version of this article (10.1186/s12864-018-5251-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shicheng Yu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China. .,Wuhan Frasergen Bioinformatics, Wuhan East Lake High-tech Zone, Wuhan, 430075, China.
| | - Chaoran Zheng
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Fan Zhou
- Wuhan Frasergen Bioinformatics, Wuhan East Lake High-tech Zone, Wuhan, 430075, China
| | - David L Baillie
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Ann M Rose
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Zixin Deng
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China.
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75
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Juárez-Reyes A, Castaño I. Chromatin architecture and virulence-related gene expression in eukaryotic microbial pathogens. Curr Genet 2018; 65:435-443. [PMID: 30443783 DOI: 10.1007/s00294-018-0903-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 10/30/2018] [Accepted: 11/10/2018] [Indexed: 12/19/2022]
Abstract
A fundamental question in biology is to understand how appropriate transcriptional regulation and dense packaging of the genetic material within the eukaryotic nucleus are achieved. The exquisite gene expression control and other metabolic processes of DNA require a highly complex, multilayered, three-dimensional architecture of the chromatin and its specific compartmentalization within the nucleus. Some of these architectural and sub-nuclear positioning mechanisms have been extensively co-opted by eukaryotic pathogens to keep fine expression control and expansion of virulence-related gene families in Plasmodium falciparum, Trypanosoma brucei and Candida glabrata. For example non-linear interactions between distant cis-acting regions and the formation of chromatin loops are required for appropriate regulation of the expression of virulence-related multi-gene families encoding cell surface proteins. These gene families are located near the chromosome ends and tethered to the nuclear periphery. Consequently, only one or very few genes of the family are expressed at a time. These genes are involved in antigenic variation in parasites and the generation of subpopulations of cells with diverse antigenic proteins at the surface in some pathogenic fungi, making them highly efficient pathogens.
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Affiliation(s)
- Alejandro Juárez-Reyes
- División de Biología Molecular, IPICYT, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, 78216, San Luis Potosí, SLP, Mexico
| | - Irene Castaño
- División de Biología Molecular, IPICYT, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, 78216, San Luis Potosí, SLP, Mexico.
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76
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Batugedara G, Le Roch KG. Unraveling the 3D genome of human malaria parasites. Semin Cell Dev Biol 2018; 90:144-153. [PMID: 30009946 DOI: 10.1016/j.semcdb.2018.07.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 07/03/2018] [Indexed: 01/31/2023]
Abstract
The chromosomes within the eukaryotic cell nucleus are highly dynamic and adopt complex hierarchical structures. Understanding how this three-dimensional (3D) nuclear architectureaffects gene regulation, cell cycle progression and disease pathogenesis are important biological questions in development and disease. Recently, many genome-wide technologies including chromosome conformation capture (3C) and 3C-based methodologies (4C, 5C, and Hi-C) have been developed to investigate 3D chromatin structure. In this review, we introduce 3D genome methodologies, with a focus on their application for understanding the nuclear architecture of the human malaria parasite, Plasmodium falciparum. An increasing amount of evidence now suggests that gene regulation in the parasite is largely regulated by epigenetic mechanisms and nuclear reorganization. Here, we explore the 3D genome architecture of P. falciparum, including local and global chromatin structure. In addition, molecular components important for maintaining 3D chromatin organization including architectural proteins and long non-coding RNAs are discussed. Collectively, these studies contribute to our understanding of how the plasticity of 3D genome architecture regulates gene expression and cell cycle progression in this deadly parasite.
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Affiliation(s)
- Gayani Batugedara
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Karine G Le Roch
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA.
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77
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Diament A, Tuller T. Modeling three-dimensional genomic organization in evolution and pathogenesis. Semin Cell Dev Biol 2018; 90:78-93. [PMID: 30030143 DOI: 10.1016/j.semcdb.2018.07.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 07/08/2018] [Indexed: 12/17/2022]
Abstract
The regulation of gene expression is mediated via the complex three-dimensional (3D) conformation of the genetic material and its interactions with various intracellular factors. Various experimental and computational approaches have been developed in recent years for understating the relation between the 3D conformation of the genome and the phenotypes of cells in normal condition and diseases. In this review, we will discuss novel approaches for analyzing and modeling the 3D genomic conformation, focusing on deciphering disease-causing mutations that affect gene expression. We conclude that as this is a very challenging mission, an important direction should involve the comparative analysis of various 3D models from various organisms or cells.
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Affiliation(s)
- Alon Diament
- Dept. of Biomedical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Tamir Tuller
- Dept. of Biomedical Engineering, Tel Aviv University, Tel Aviv 6997801, Israel; The Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv 6997801, Israel.
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78
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Abstract
Eukaryotic pathogens must survive in different hosts, respond to changing environments, and exploit specialized niches to propagate. Plasmodium parasites cause human malaria during bloodstream infections, where they must persist long enough to be transmitted. Parasites have evolved diverse strategies of variant gene expression that control critical biological processes of blood-stage infections, including antigenic variation, erythrocyte invasion, innate immune evasion, and nutrient acquisition, as well as life-cycle transitions. Epigenetic mechanisms within the parasite are being elucidated, with discovery of epigenomic marks associated with gene silencing and activation, and the identification of epigenetic regulators and chromatin proteins that are required for the switching and maintenance of gene expression. Here, we review the key epigenetic processes that facilitate transition through the parasite life cycle and epigenetic regulatory mechanisms utilized by Plasmodium parasites to survive changing environments and consider epigenetic switching in the context of the outcome of human infections.
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Affiliation(s)
- Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA; ,
| | - Kristen M Skillman
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA; ,
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79
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Varoquaux N. Unfolding the Genome: The Case Study of P. falciparum. Int J Biostat 2018; 15:ijb-2017-0061. [PMID: 29878883 DOI: 10.1515/ijb-2017-0061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 05/10/2018] [Indexed: 11/15/2022]
Abstract
The development of new ways to probe samples for the three-dimensional (3D) structure of DNA paves the way for in depth and systematic analyses of the genome architecture. 3C-like methods coupled with high-throughput sequencing can now assess physical interactions between pairs of loci in a genome-wide fashion, thus enabling the creation of genome-by-genome contact maps. The spreading of such protocols creates many new opportunities for methodological development: how can we infer 3D models from these contact maps? Can such models help us gain insights into biological processes? Several recent studies applied such protocols to P. falciparum (the deadliest of the five human malaria parasites), assessing its genome organization at different moments of its life cycle. With its small genomic size, fairly simple (yet changing) genomic organization during its lifecyle and strong correlation between chromatin folding and gene expression, this parasite is the ideal case study for applying and developing methods to infer 3D models and use them for downstream analysis. Here, I review a set of methods used to build and analyse three-dimensional models from contact maps data with a special highlight on P. falciparum's genome organization.
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Affiliation(s)
- Nelle Varoquaux
- Statistics, University of California, Berkeley, 367 Evans Hall, Berkeley, California, USA
- Berkeley Institute for Data Science, 190, Doe libraryBerkeley, United States of America
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80
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Rada-Iglesias A, Grosveld FG, Papantonis A. Forces driving the three-dimensional folding of eukaryotic genomes. Mol Syst Biol 2018; 14:e8214. [PMID: 29858282 PMCID: PMC6024091 DOI: 10.15252/msb.20188214] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The last decade has radically renewed our understanding of higher order chromatin folding in the eukaryotic nucleus. As a result, most current models are in support of a mostly hierarchical and relatively stable folding of chromosomes dividing chromosomal territories into A‐ (active) and B‐ (inactive) compartments, which are then further partitioned into topologically associating domains (TADs), each of which is made up from multiple loops stabilized mainly by the CTCF and cohesin chromatin‐binding complexes. Nonetheless, the structure‐to‐function relationship of eukaryotic genomes is still not well understood. Here, we focus on recent work highlighting the biophysical and regulatory forces that contribute to the spatial organization of genomes, and we propose that the various conformations that chromatin assumes are not so much the result of a linear hierarchy, but rather of both converging and conflicting dynamic forces that act on it.
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Affiliation(s)
- Alvaro Rada-Iglesias
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany .,CECAD, University of Cologne, Cologne, Germany
| | - Frank G Grosveld
- Department of Cell Biology, Erasmus Medical Center, GE Rotterdam, Netherlands
| | - Argyris Papantonis
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
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81
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Segal MR, Bengtsson HL. Improved accuracy assessment for 3D genome reconstructions. BMC Bioinformatics 2018; 19:196. [PMID: 29848293 PMCID: PMC5977474 DOI: 10.1186/s12859-018-2214-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 05/21/2018] [Indexed: 12/21/2022] Open
Abstract
Background Three dimensional (3D) genome spatial organization is critical for numerous cellular functions, including transcription, while certain conformation-driven structural alterations are frequently oncogenic. Genome conformation had been difficult to elucidate but the advent chromatin conformation capture assays, notably Hi-C, has transformed understanding of chromatin architecture and yielded numerous biological insights. Although most of these findings have flowed from analysis of proximity data produced by these assays, added value in generating 3D reconstructions has been demonstrated, deriving, in part, from superposing genomic features on the reconstruction. However, advantages of 3D structure-based analyses are clearly conditional on the accuracy of the attendant reconstructions, which is difficult to assess. Proponents of competing reconstruction algorithms have evaluated their accuracy by recourse to simulation of toy structures and/or limited fluorescence in situ hybridization (FISH) imaging that features a handful of low resolution probes. Accordingly, new methods of reconstruction accuracy assessment are needed. Results Here we utilize two recently devised assays to develop methodology for assessing 3D reconstruction accuracy. Multiplex FISH increases the number of probes by an order of magnitude and hence the number of inter-probe distances by two orders, providing sufficient information for structure-level evaluation via mean-squared deviations (MSD). Crucially, underscoring multiplex FISH applications are large numbers of coordinate-system aligned replicates that provide the basis for a referent distribution for MSD statistics. Using this system we show that reconstructions based on Hi-C data for IMR90 cells are accurate for some chromosomes but not others. The second new assay, genome architecture mapping, utilizes large numbers of thin cryosections to obtain a measure of proximity. We exploit the planarity of the cryosections – not used in inferring proximity – to obtain measures of reconstruction accuracy, with referents provided via resampling. Application to mouse embryonic stem cells shows reconstruction accuracies that vary by chromosome. Conclusions We have developed methods for assessing the accuracy of 3D genome reconstructions that exploit features of recently advanced multiplex FISH and genome architecture mapping assays. These approaches can help overcome the absence of gold standards for making such assessments which are important in view of the considerable uncertainties surrounding 3D genome reconstruction.
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Affiliation(s)
- Mark R Segal
- Division of Bioinformatics, Department of Epidemiology and Biostatistics, UCSF, 16th Street, San Francisco, 94158, USA.
| | - Henrik L Bengtsson
- Division of Bioinformatics, Department of Epidemiology and Biostatistics, UCSF, 16th Street, San Francisco, 94158, USA
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82
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Liu W, Luo Z, Wang Y, Pham NT, Tuck L, Pérez-Pi I, Liu L, Shen Y, French C, Auer M, Marles-Wright J, Dai J, Cai Y. Rapid pathway prototyping and engineering using in vitro and in vivo synthetic genome SCRaMbLE-in methods. Nat Commun 2018; 9:1936. [PMID: 29789543 PMCID: PMC5964202 DOI: 10.1038/s41467-018-04254-0] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/11/2018] [Indexed: 12/11/2022] Open
Abstract
Exogenous pathway optimization and chassis engineering are two crucial methods for heterologous pathway expression. The two methods are normally carried out step-wise and in a trial-and-error manner. Here we report a recombinase-based combinatorial method (termed "SCRaMbLE-in") to tackle both challenges simultaneously. SCRaMbLE-in includes an in vitro recombinase toolkit to rapidly prototype and diversify gene expression at the pathway level and an in vivo genome reshuffling system to integrate assembled pathways into the synthetic yeast genome while combinatorially causing massive genome rearrangements in the host chassis. A set of loxP mutant pairs was identified to maximize the efficiency of the in vitro diversification. Exemplar pathways of β-carotene and violacein were successfully assembled, diversified, and integrated using this SCRaMbLE-in method. High-throughput sequencing was performed on selected engineered strains to reveal the resulting genotype-to-phenotype relationships. The SCRaMbLE-in method proves to be a rapid, efficient, and universal method to fast track the cycle of engineering biology.
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Affiliation(s)
- Wei Liu
- School of Biological Sciences, The King's Buildings, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Zhouqing Luo
- Center for Synthetic Genomics, Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China
| | - Yun Wang
- BGI-Shenzhen, Beishan Industrial Zone, 518083, Shenzhen, China.,China National GeneBank, BGI-Shenzhen, Jinsha Road, 518120, Shenzhen, China.,Guangdong Provincial Key Laboratory of Genome Read and Write, Jinsha Road, 518120, Shenzhen, China
| | - Nhan T Pham
- School of Biological Sciences, The King's Buildings, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Laura Tuck
- School of Biological Sciences, The King's Buildings, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Irene Pérez-Pi
- School of Biological Sciences, The King's Buildings, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Longying Liu
- BGI-Shenzhen, Beishan Industrial Zone, 518083, Shenzhen, China.,China National GeneBank, BGI-Shenzhen, Jinsha Road, 518120, Shenzhen, China.,Guangdong Provincial Key Laboratory of Genome Read and Write, Jinsha Road, 518120, Shenzhen, China
| | - Yue Shen
- School of Biological Sciences, The King's Buildings, University of Edinburgh, Edinburgh, EH9 3BF, UK.,BGI-Shenzhen, Beishan Industrial Zone, 518083, Shenzhen, China.,China National GeneBank, BGI-Shenzhen, Jinsha Road, 518120, Shenzhen, China.,Guangdong Provincial Key Laboratory of Genome Read and Write, Jinsha Road, 518120, Shenzhen, China.,Manchester Institute of Biotechnology, University of Manchester, Manchester, M1 7DN, UK
| | - Chris French
- School of Biological Sciences, The King's Buildings, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Manfred Auer
- School of Biological Sciences, The King's Buildings, University of Edinburgh, Edinburgh, EH9 3BF, UK.,Edinburgh Medical School, Biomedical Sciences, The King's Buildings, Edinburgh, EH9 3BF, UK
| | - Jon Marles-Wright
- School of Natural and Environmental Sciences, Devonshire Building, Newcastle University, Newcastle upon, Tyne, NE1 7RX, UK
| | - Junbiao Dai
- Center for Synthetic Genomics, Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China.
| | - Yizhi Cai
- Center for Synthetic Genomics, Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China. .,Manchester Institute of Biotechnology, University of Manchester, Manchester, M1 7DN, UK.
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83
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Bunnik EM, Cook KB, Varoquaux N, Batugedara G, Prudhomme J, Cort A, Shi L, Andolina C, Ross LS, Brady D, Fidock DA, Nosten F, Tewari R, Sinnis P, Ay F, Vert JP, Noble WS, Le Roch KG. Changes in genome organization of parasite-specific gene families during the Plasmodium transmission stages. Nat Commun 2018; 9:1910. [PMID: 29765020 PMCID: PMC5954139 DOI: 10.1038/s41467-018-04295-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 04/18/2018] [Indexed: 12/20/2022] Open
Abstract
The development of malaria parasites throughout their various life cycle stages is coordinated by changes in gene expression. We previously showed that the three-dimensional organization of the Plasmodium falciparum genome is strongly associated with gene expression during its replication cycle inside red blood cells. Here, we analyze genome organization in the P. falciparum and P. vivax transmission stages. Major changes occur in the localization and interactions of genes involved in pathogenesis and immune evasion, host cell invasion, sexual differentiation, and master regulation of gene expression. Furthermore, we observe reorganization of subtelomeric heterochromatin around genes involved in host cell remodeling. Depletion of heterochromatin protein 1 (PfHP1) resulted in loss of interactions between virulence genes, confirming that PfHP1 is essential for maintenance of the repressive center. Our results suggest that the three-dimensional genome structure of human malaria parasites is strongly connected with transcriptional activity of specific gene families throughout the life cycle.
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Affiliation(s)
- Evelien M Bunnik
- Department of Microbiology, Immunology & Molecular Genetics, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA
- Department of Molecular, Cell and Systems Biology, University of California Riverside, 900 University Ave, Riverside, CA, 92521, USA
| | - Kate B Cook
- Department of Genome Sciences, University of Washington, 3720 15th Ave NE, Seattle, WA, 98195, USA
| | - Nelle Varoquaux
- Department of Statistics, University of California, 367 Evans Hall, Berkeley, CA, 94720, USA
- Berkeley Institute for Data Science, 190 Doe Library, Berkeley, CA, 94720, USA
- MINES ParisTech, PSL Research University, CBIO-Centre for Computational Biology, 60 boulevard Saint-Michel, 75006, Paris, France
- Institut Curie, 75248, Paris, France
- U900, INSERM, Paris, 75248, France
| | - Gayani Batugedara
- Department of Molecular, Cell and Systems Biology, University of California Riverside, 900 University Ave, Riverside, CA, 92521, USA
| | - Jacques Prudhomme
- Department of Molecular, Cell and Systems Biology, University of California Riverside, 900 University Ave, Riverside, CA, 92521, USA
| | - Anthony Cort
- Department of Molecular, Cell and Systems Biology, University of California Riverside, 900 University Ave, Riverside, CA, 92521, USA
| | - Lirong Shi
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615N. Wolfe Street, E5132, Baltimore, MD, 21205, USA
| | - Chiara Andolina
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research building, University of Oxford, Old Road campus, Roosevelt Drive, Headington, Oxford, OX3 7FZ, UK
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, 63110, Thailand
| | - Leila S Ross
- Department of Microbiology and Immunology, Columbia University Medical Center, 701W. 168 St., HHSC 1208, New York, NY, 10032, USA
| | - Declan Brady
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
| | - David A Fidock
- Department of Microbiology and Immunology, Columbia University Medical Center, 701W. 168 St., HHSC 1208, New York, NY, 10032, USA
- Division of Infectious Diseases, Department of Medicine, Columbia University, New York, NY, 10032, USA
| | - Francois Nosten
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research building, University of Oxford, Old Road campus, Roosevelt Drive, Headington, Oxford, OX3 7FZ, UK
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, 63110, Thailand
| | - Rita Tewari
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Photini Sinnis
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615N. Wolfe Street, E5132, Baltimore, MD, 21205, USA
| | - Ferhat Ay
- La Jolla Institute for Allergy & Immunology, 9420 Athena Cir, La Jolla, CA, 92037, USA
| | - Jean-Philippe Vert
- MINES ParisTech, PSL Research University, CBIO-Centre for Computational Biology, 60 boulevard Saint-Michel, 75006, Paris, France
- Institut Curie, 75248, Paris, France
- U900, INSERM, Paris, 75248, France
- Département de mathématiques et applications, École normale supérieure, CNRS, PSL Research University, Paris, 75005, France
| | - William Stafford Noble
- Department of Genome Sciences, University of Washington, 3720 15th Ave NE, Seattle, WA, 98195, USA.
- Department of Computer Science and Engineering, University of Washington, Seattle, WA, 98195, USA.
| | - Karine G Le Roch
- Department of Molecular, Cell and Systems Biology, University of California Riverside, 900 University Ave, Riverside, CA, 92521, USA.
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84
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Toenhake CG, Fraschka SAK, Vijayabaskar MS, Westhead DR, van Heeringen SJ, Bártfai R. Chromatin Accessibility-Based Characterization of the Gene Regulatory Network Underlying Plasmodium falciparum Blood-Stage Development. Cell Host Microbe 2018; 23:557-569.e9. [PMID: 29649445 PMCID: PMC5899830 DOI: 10.1016/j.chom.2018.03.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 02/05/2018] [Accepted: 03/05/2018] [Indexed: 02/07/2023]
Abstract
Underlying the development of malaria parasites within erythrocytes and the resulting pathogenicity is a hardwired program that secures proper timing of gene transcription and production of functionally relevant proteins. How stage-specific gene expression is orchestrated in vivo remains unclear. Here, using the assay for transposase accessible chromatin sequencing (ATAC-seq), we identified ∼4,000 regulatory regions in P. falciparum intraerythrocytic stages. The vast majority of these sites are located within 2 kb upstream of transcribed genes and their chromatin accessibility pattern correlates positively with abundance of the respective mRNA transcript. Importantly, these regions are sufficient to drive stage-specific reporter gene expression and DNA motifs enriched in stage-specific sets of regulatory regions interact with members of the P. falciparum AP2 transcription factor family. Collectively, this study provides initial insights into the in vivo gene regulatory network of P. falciparum intraerythrocytic stages and should serve as a valuable resource for future studies.
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Affiliation(s)
- Christa Geeke Toenhake
- Radboud University, Faculty of Science, Department of Molecular Biology, Nijmegen, 6525 GA, the Netherlands
| | | | | | - David Robert Westhead
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Simon Jan van Heeringen
- Radboud University, Faculty of Science, Department of Molecular Developmental Biology, Nijmegen, 6525 GA, the Netherlands
| | - Richárd Bártfai
- Radboud University, Faculty of Science, Department of Molecular Biology, Nijmegen, 6525 GA, the Netherlands.
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85
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Abstract
Chromosome conformation capture technologies such as Hi-C are widely used to investigate the spatial organization of genomes. Because genome structures can vary considerably between individual cells of a population, interpreting ensemble-averaged Hi-C data can be challenging, in particular for long-range and interchromosomal interactions. We pioneered a probabilistic approach for the generation of a population of distinct diploid 3D genome structures consistent with all the chromatin-chromatin interaction probabilities from Hi-C experiments. Each structure in the population is a physical model of the genome in 3D. Analysis of these models yields new insights into the causes and the functional properties of the genome's organization in space and time. We provide a user-friendly software package, called PGS, which runs on local machines (for practice runs) and high-performance computing platforms. PGS takes a genome-wide Hi-C contact frequency matrix, along with information about genome segmentation, and produces an ensemble of 3D genome structures entirely consistent with the input. The software automatically generates an analysis report, and provides tools to extract and analyze the 3D coordinates of specific domains. Basic Linux command-line knowledge is sufficient for using this software. A typical running time of the pipeline is ∼3 d with 300 cores on a computer cluster to generate a population of 1,000 diploid genome structures at topological-associated domain (TAD)-level resolution.
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86
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Arzate-Mejía RG, Recillas-Targa F, Corces VG. Developing in 3D: the role of CTCF in cell differentiation. Development 2018; 145:dev137729. [PMID: 29567640 PMCID: PMC5897592 DOI: 10.1242/dev.137729] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
CTCF is a highly conserved zinc-finger DNA-binding protein that mediates interactions between distant sequences in the genome. As a consequence, CTCF regulates enhancer-promoter interactions and contributes to the three-dimensional organization of the genome. Recent studies indicate that CTCF is developmentally regulated, suggesting that it plays a role in cell type-specific genome organization. Here, we review these studies and discuss how CTCF functions during the development of various cell and tissue types, ranging from embryonic stem cells and gametes, to neural, muscle and cardiac cells. We propose that the lineage-specific control of CTCF levels, and its partnership with lineage-specific transcription factors, allows for the control of cell type-specific gene expression via chromatin looping.
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Affiliation(s)
- Rodrigo G Arzate-Mejía
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Ciudad de México, México
| | - Félix Recillas-Targa
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Ciudad de México, México
| | - Victor G Corces
- Department of Biology, Emory University, Atlanta, GA 30322, USA
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87
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Computational methods for analyzing genome-wide chromosome conformation capture data. Curr Opin Biotechnol 2018; 54:98-105. [PMID: 29550705 DOI: 10.1016/j.copbio.2018.01.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 12/31/2017] [Accepted: 01/22/2018] [Indexed: 11/23/2022]
Abstract
In all organisms, chromatin is packed to fulfil structural constraints and functional requirements. The hierarchical model of chromatin organization in the 3D nuclear space encompasses different topologies at diverse scale lengths, with chromosomes occupying distinct volumes, further organized in compartments, inside which the chromatin fibers fold into large domains and short-range loops. In the recent years, the combination of chromosome conformation capture (3C) techniques and high-throughput sequencing allowed probing chromatin spatial organization at the whole genome-scale. 3C-based methods produce enormous amounts of genomic data that are analyzed using ad-hoc computational procedures. Here, we review the common pipelines and methods for the analysis of genome-wide chromosome conformation capture data, highlighting recent developments in key steps for the identification of chromatin structures.
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88
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Abstract
It is well known that the chromosomes are organized in the nucleus and this spatial arrangement of genome play a crucial role in gene regulation and genome stability. Different techniques have been developed and applied to uncover the intrinsic mechanism of genome architecture, especially the chromosome conformation capture (3C) and 3C-derived methods. 3C and 3C-derived techniques provide us approaches to perform high-throughput chromatin architecture assays at the genome scale. However, the advantage and disadvantage of current methodologies of C-technologies have not been discussed extensively. In this review, we described and compared the methodologies of C-technologies used in genome organization studies with an emphasis on Hi-C method. We also discussed the crucial challenges facing current genome architecture studies based on 3C and 3C-derived technologies and the direction of future technologies to address currently outstanding questions in the field. These latest news contribute to our current understanding of genome structure, and provide a comprehensive reference for researchers to choose the appropriate method in future application. We consider that these constantly improving technologies will offer a finer and more accurate contact profiles of entire genome and ultimately reveal specific molecular machines govern its shape and function.
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89
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Galinski MR, Lapp SA, Peterson MS, Ay F, Joyner CJ, LE Roch KG, Fonseca LL, Voit EO. Plasmodium knowlesi: a superb in vivo nonhuman primate model of antigenic variation in malaria. Parasitology 2018; 145:85-100. [PMID: 28712361 PMCID: PMC5798396 DOI: 10.1017/s0031182017001135] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 06/03/2017] [Accepted: 06/06/2017] [Indexed: 02/08/2023]
Abstract
Antigenic variation in malaria was discovered in Plasmodium knowlesi studies involving longitudinal infections of rhesus macaques (M. mulatta). The variant proteins, known as the P. knowlesi Schizont Infected Cell Agglutination (SICA) antigens and the P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1) antigens, expressed by the SICAvar and var multigene families, respectively, have been studied for over 30 years. Expression of the SICA antigens in P. knowlesi requires a splenic component, and specific antibodies are necessary for variant antigen switch events in vivo. Outstanding questions revolve around the role of the spleen and the mechanisms by which the expression of these variant antigen families are regulated. Importantly, the longitudinal dynamics and molecular mechanisms that govern variant antigen expression can be studied with P. knowlesi infection of its mammalian and vector hosts. Synchronous infections can be initiated with established clones and studied at multi-omic levels, with the benefit of computational tools from systems biology that permit the integration of datasets and the design of explanatory, predictive mathematical models. Here we provide an historical account of this topic, while highlighting the potential for maximizing the use of P. knowlesi - macaque model systems and summarizing exciting new progress in this area of research.
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Affiliation(s)
- M R Galinski
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta,GA,USA
| | - S A Lapp
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta,GA,USA
| | - M S Peterson
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta,GA,USA
| | - F Ay
- La Jolla Institute for Allergy and Immunology,La Jolla,CA 92037,USA
| | - C J Joyner
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta,GA,USA
| | - K G LE Roch
- Department of Cell Biology & Neuroscience,Center for Disease and Vector Research,Institute for Integrative Genome Biology,University of California Riverside,CA 92521,USA
| | - L L Fonseca
- The Wallace H. Coulter Department of Biomedical Engineering,Georgia Institute of Technology and Emory University,Atlanta,Georgia,30332-2000,USA
| | - E O Voit
- The Wallace H. Coulter Department of Biomedical Engineering,Georgia Institute of Technology and Emory University,Atlanta,Georgia,30332-2000,USA
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90
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Lapp SA, Geraldo JA, Chien JT, Ay F, Pakala SB, Batugedara G, Humphrey J, DeBARRY JD, Le Roch KG, Galinski MR, Kissinger JC. PacBio assembly of a Plasmodium knowlesi genome sequence with Hi-C correction and manual annotation of the SICAvar gene family. Parasitology 2018; 145:71-84. [PMID: 28720171 PMCID: PMC5798397 DOI: 10.1017/s0031182017001329] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/09/2017] [Accepted: 06/20/2017] [Indexed: 12/20/2022]
Abstract
Plasmodium knowlesi has risen in importance as a zoonotic parasite that has been causing regular episodes of malaria throughout South East Asia. The P. knowlesi genome sequence generated in 2008 highlighted and confirmed many similarities and differences in Plasmodium species, including a global view of several multigene families, such as the large SICAvar multigene family encoding the variant antigens known as the schizont-infected cell agglutination proteins. However, repetitive DNA sequences are the bane of any genome project, and this and other Plasmodium genome projects have not been immune to the gaps, rearrangements and other pitfalls created by these genomic features. Today, long-read PacBio and chromatin conformation technologies are overcoming such obstacles. Here, based on the use of these technologies, we present a highly refined de novo P. knowlesi genome sequence of the Pk1(A+) clone. This sequence and annotation, referred to as the 'MaHPIC Pk genome sequence', includes manual annotation of the SICAvar gene family with 136 full-length members categorized as type I or II. This sequence provides a framework that will permit a better understanding of the SICAvar repertoire, selective pressures acting on this gene family and mechanisms of antigenic variation in this species and other pathogens.
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Affiliation(s)
- S A Lapp
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta, GA,USA
| | - J A Geraldo
- Federal University of Minas Gerais,Belo Horizonte, MG,Brazil
| | - J-T Chien
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta, GA,USA
| | - F Ay
- La Jolla Institute for Allergy and Immunology,La Jolla, CA 92037,USA
| | - S B Pakala
- Institute of Bioinformatics, University of Georgia,Athens, GA 30602,USA
| | - G Batugedara
- Center for Disease and Vector Research,Institute for Integrative Genome Biology,Department of Cell Biology & Neuroscience,University of California Riverside,CA 92521,USA
| | - J Humphrey
- Institute of Bioinformatics, University of Georgia,Athens, GA 30602,USA
| | - J D DeBARRY
- Institute of Bioinformatics, University of Georgia,Athens, GA 30602,USA
| | - K G Le Roch
- Center for Disease and Vector Research,Institute for Integrative Genome Biology,Department of Cell Biology & Neuroscience,University of California Riverside,CA 92521,USA
| | - M R Galinski
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta, GA,USA
| | - J C Kissinger
- Institute of Bioinformatics, University of Georgia,Athens, GA 30602,USA
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91
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Gürsoy G, Xu Y, Kenter AL, Liang J. Computational construction of 3D chromatin ensembles and prediction of functional interactions of alpha-globin locus from 5C data. Nucleic Acids Res 2017; 45:11547-11558. [PMID: 28981716 PMCID: PMC5714131 DOI: 10.1093/nar/gkx784] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 08/30/2017] [Indexed: 01/23/2023] Open
Abstract
Conformation capture technologies measure frequencies of interactions between chromatin regions. However, understanding gene-regulation require knowledge of detailed spatial structures of heterogeneous chromatin in cells. Here we describe the nC-SAC (n-Constrained-Self Avoiding Chromatin) method that transforms experimental interaction frequencies into 3D ensembles of chromatin chains. nC-SAC first distinguishes specific from non-specific interaction frequencies, then generates 3D chromatin ensembles using identified specific interactions as spatial constraints. Application to α-globin locus shows that these constraints (∼20%) drive the formation of ∼99% all experimentally captured interactions, in which ∼30% additional to the imposed constraints is found to be specific. Many novel specific spatial contacts not captured by experiments are also predicted. A subset, of which independent ChIA-PET data are available, is validated to be RNAPII-, CTCF-, and RAD21-mediated. Their positioning in the architectural context of imposed specific interactions from nC-SAC is highly important. Our results also suggest the presence of a many-body structural unit involving α-globin gene, its enhancers, and POL3RK gene for regulating the expression of α-globin in silent cells.
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Affiliation(s)
- Gamze Gürsoy
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Yun Xu
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Amy L Kenter
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612, USA
| | - Jie Liang
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
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92
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Chakraborty A, Ay F. Identification of copy number variations and translocations in cancer cells from Hi-C data. Bioinformatics 2017; 34:338-345. [PMID: 29048467 DOI: 10.1093/bioinformatics/btx664] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 09/21/2017] [Accepted: 10/17/2017] [Indexed: 11/14/2022] Open
Abstract
MOTIVATION Eukaryotic chromosomes adapt a complex and highly dynamic three-dimensional (3D) structure, which profoundly affects different cellular functions and outcomes including changes in epigenetic landscape and in gene expression. Making the scenario even more complex, cancer cells harbor chromosomal abnormalities [e.g. copy number variations (CNVs) and translocations] altering their genomes both at the sequence level and at the level of 3D organization. High-throughput chromosome conformation capture techniques (e.g. Hi-C), which are originally developed for decoding the 3D structure of the chromatin, provide a great opportunity to simultaneously identify the locations of genomic rearrangements and to investigate the 3D genome organization in cancer cells. Even though Hi-C data has been used for validating known rearrangements, computational methods that can distinguish rearrangement signals from the inherent biases of Hi-C data and from the actual 3D conformation of chromatin, and can precisely detect rearrangement locations de novo have been missing. RESULTS In this work, we characterize how intra and inter-chromosomal Hi-C contacts are distributed for normal and rearranged chromosomes to devise a new set of algorithms (i) to identify genomic segments that correspond to CNV regions such as amplifications and deletions (HiCnv), (ii) to call inter-chromosomal translocations and their boundaries (HiCtrans) from Hi-C experiments and (iii) to simulate Hi-C data from genomes with desired rearrangements and abnormalities (AveSim) in order to select optimal parameters for and to benchmark the accuracy of our methods. Our results on 10 different cancer cell lines with Hi-C data show that we identify a total number of 105 amplifications and 45 deletions together with 90 translocations, whereas we identify virtually no such events for two karyotypically normal cell lines. Our CNV predictions correlate very well with whole genome sequencing data among chromosomes with CNV events for a breast cancer cell line (r = 0.89) and capture most of the CNVs we simulate using Avesim. For HiCtrans predictions, we report evidence from the literature for 30 out of 90 translocations for eight of our cancer cell lines. Furthermore, we show that our tools identify and correctly classify relatively understudied rearrangements such as double minutes and homogeneously staining regions. Considering the inherent limitations of existing techniques for karyotyping (i.e. missing balanced rearrangements and those near repetitive regions), the accurate identification of CNVs and translocations in a cost-effective and high-throughput setting is still a challenge. Our results show that the set of tools we develop effectively utilize moderately sequenced Hi-C libraries (100-300 million reads) to identify known and de novo chromosomal rearrangements/abnormalities in well-established cancer cell lines. With the decrease in required number of cells and the increase in attainable resolution, we believe that our framework will pave the way towards comprehensive mapping of genomic rearrangements in primary cells from cancer patients using Hi-C. AVAILABILITY AND IMPLEMENTATION CNV calling: https://github.com/ay-lab/HiCnv, Translocation calling: https://github.com/ay-lab/HiCtrans and Hi-C simulation: https://github.com/ay-lab/AveSim. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Abhijit Chakraborty
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA
| | - Ferhat Ay
- Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA.,School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, USA
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93
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Abstract
Protozoan parasites colonize numerous metazoan hosts and insect vectors through their life cycles, with the need to respond quickly and reversibly while encountering diverse and often hostile ecological niches. To succeed, parasites must also persist within individuals until transmission between hosts is achieved. Several parasitic protozoa cause a huge burden of disease in humans and livestock, and here we focus on the parasites that cause malaria and African trypanosomiasis. Efforts to understand how these pathogens adapt to survive in varied host environments, cause disease, and transmit between hosts have revealed a wealth of epigenetic phenomena. Epigenetic switching mechanisms appear to be ideally suited for the regulation of clonal antigenic variation underlying successful parasitism. We review the molecular players and complex mechanistic layers that mediate the epigenetic regulation of virulence gene expression. Understanding epigenetic processes will aid the development of antiparasitic therapeutics.
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Affiliation(s)
- Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, 651 Huntington Avenue, Boston, MA 02115, USA.
| | - David Horn
- Division of Biological Chemistry & Drug Discovery, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
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94
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Diament A, Tuller T. Tracking the evolution of 3D gene organization demonstrates its connection to phenotypic divergence. Nucleic Acids Res 2017; 45:4330-4343. [PMID: 28369658 PMCID: PMC5416853 DOI: 10.1093/nar/gkx205] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 03/20/2017] [Indexed: 12/20/2022] Open
Abstract
It has recently been shown that the organization of genes in eukaryotic genomes, and specifically in 3D, is strongly related to gene expression and function and partially conserved between organisms. However, previous studies of 3D genomic organization analyzed each organism independently from others. Here, we propose an approach for unified inter-organismal analysis of gene organization based on a network representation of Hi-C data. We define and detect four classes of spatially co-evolving orthologous modules (SCOMs), i.e. gene families that co-evolve in their 3D organization, based on patterns of divergence and conservation of distances. We demonstrate our methodology on Hi-C data from Saccharomyces cerevisiae and Schizosaccharomyces pombe, and identify, among others, modules relating to RNA splicing machinery and chromatin silencing by small RNA which are central to S. pombe's lifestyle. Our results emphasize the importance of 3D genomic organization in eukaryotes and suggest that the evolutionary mechanisms that shape gene organization affect the organism fitness and phenotypes. The proposed algorithms can be utilized in future studies of genome evolution and comparative analysis of spatial genomic organization in different tissues, conditions and single cells.
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Affiliation(s)
- Alon Diament
- Biomedical Engineering Dept., Tel Aviv University, Tel Aviv 6997801, Israel
| | - Tamir Tuller
- Biomedical Engineering Dept., Tel Aviv University, Tel Aviv 6997801, Israel.,The Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
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95
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Ubhe S, Rawat M, Verma S, Anamika K, Karmodiya K. Genome-wide identification of novel intergenic enhancer-like elements: implications in the regulation of transcription in Plasmodium falciparum. BMC Genomics 2017; 18:656. [PMID: 28836940 PMCID: PMC5569477 DOI: 10.1186/s12864-017-4052-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 08/11/2017] [Indexed: 01/28/2023] Open
Abstract
Background The molecular mechanisms of transcriptional regulation are poorly understood in Plasmodium falciparum. In addition, most of the genes in Plasmodium falciparum are transcriptionally poised and only a handful of cis-regulatory elements are known to operate in transcriptional regulation. Here, we employed an epigenetic signature based approach to identify significance of previously uncharacterised intergenic regions enriched with histone modification marks leading to discovery of enhancer-like elements. Results We found that enhancer-like elements are significantly enriched with H3K4me1, generate unique non-coding bi-directional RNAs and majority of them can function as cis-regulators. Furthermore, functional enhancer reporter assay demonstrates that the enhancer-like elements regulate transcription of target genes in Plasmodium falciparum. Our study also suggests that the Plasmodium genome segregates functionally related genes into discrete housekeeping and pathogenicity/virulence clusters, presumably for robust transcriptional control of virulence/pathogenicity genes. Conclusions This report contributes to the understanding of parasite regulatory genomics by identification of enhancer-like elements, defining their epigenetic and transcriptional features and provides a resource of functional cis-regulatory elements that may give insights into the virulence/pathogenicity of Plasmodium falciparum. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-4052-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Suyog Ubhe
- Department of Biology, Indian Institute of Science Education and Research, Pashan, Pune, 411008, India
| | - Mukul Rawat
- Department of Biology, Indian Institute of Science Education and Research, Pashan, Pune, 411008, India
| | - Srikant Verma
- Labs, Persistent Systems Limited, Pingala - Aryabhata, Erandwane, Pune, 411004, India
| | - Krishanpal Anamika
- Labs, Persistent Systems Limited, Pingala - Aryabhata, Erandwane, Pune, 411004, India
| | - Krishanpal Karmodiya
- Department of Biology, Indian Institute of Science Education and Research, Pashan, Pune, 411008, India.
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96
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Rowley MJ, Nichols MH, Lyu X, Ando-Kuri M, Rivera ISM, Hermetz K, Wang P, Ruan Y, Corces VG. Evolutionarily Conserved Principles Predict 3D Chromatin Organization. Mol Cell 2017; 67:837-852.e7. [PMID: 28826674 DOI: 10.1016/j.molcel.2017.07.022] [Citation(s) in RCA: 354] [Impact Index Per Article: 50.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 06/23/2017] [Accepted: 07/21/2017] [Indexed: 01/02/2023]
Abstract
Topologically associating domains (TADs), CTCF loop domains, and A/B compartments have been identified as important structural and functional components of 3D chromatin organization, yet the relationship between these features is not well understood. Using high-resolution Hi-C and HiChIP, we show that Drosophila chromatin is organized into domains we term compartmental domains that correspond precisely with A/B compartments at high resolution. We find that transcriptional state is a major predictor of Hi-C contact maps in several eukaryotes tested, including C. elegans and A. thaliana. Architectural proteins insulate compartmental domains by reducing interaction frequencies between neighboring regions in Drosophila, but CTCF loops do not play a distinct role in this organism. In mammals, compartmental domains exist alongside CTCF loop domains to form topological domains. The results suggest that compartmental domains are responsible for domain structure in all eukaryotes, with CTCF playing an important role in domain formation in mammals.
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Affiliation(s)
- M Jordan Rowley
- Department of Biology, Emory University, 1510 Clifton Road Northeast, Atlanta, GA 30322, USA
| | - Michael H Nichols
- Department of Biology, Emory University, 1510 Clifton Road Northeast, Atlanta, GA 30322, USA
| | - Xiaowen Lyu
- Department of Biology, Emory University, 1510 Clifton Road Northeast, Atlanta, GA 30322, USA
| | - Masami Ando-Kuri
- Department of Biology, Emory University, 1510 Clifton Road Northeast, Atlanta, GA 30322, USA
| | - I Sarahi M Rivera
- Department of Biology, Emory University, 1510 Clifton Road Northeast, Atlanta, GA 30322, USA
| | - Karen Hermetz
- Department of Biology, Emory University, 1510 Clifton Road Northeast, Atlanta, GA 30322, USA
| | - Ping Wang
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Drive, Farmington, CT 06030, USA
| | - Yijun Ruan
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Drive, Farmington, CT 06030, USA
| | - Victor G Corces
- Department of Biology, Emory University, 1510 Clifton Road Northeast, Atlanta, GA 30322, USA.
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97
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Dali R, Blanchette M. A critical assessment of topologically associating domain prediction tools. Nucleic Acids Res 2017; 45:2994-3005. [PMID: 28334773 PMCID: PMC5389712 DOI: 10.1093/nar/gkx145] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 02/27/2017] [Indexed: 12/20/2022] Open
Abstract
Topologically associating domains (TADs) have been proposed to be the basic unit of chromosome folding and have been shown to play key roles in genome organization and gene regulation. Several different tools are available for TAD prediction, but their properties have never been thoroughly assessed. In this manuscript, we compare the output of seven different TAD prediction tools on two published Hi-C data sets. TAD predictions varied greatly between tools in number, size distribution and other biological properties. Assessed against a manual annotation of TADs, individual TAD boundary predictions were found to be quite reliable, but their assembly into complete TAD structures was much less so. In addition, many tools were sensitive to sequencing depth and resolution of the interaction frequency matrix. This manuscript provides users and designers of TAD prediction tools with information that will help guide the choice of tools and the interpretation of their predictions.
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Affiliation(s)
- Rola Dali
- School of Computer Science and McGill Centre for Bioinformatics, McGill University, Montreal, Canada
| | - Mathieu Blanchette
- School of Computer Science and McGill Centre for Bioinformatics, McGill University, Montreal, Canada
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98
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Lu X, Batugedara G, Lee M, Prudhomme J, Bunnik EM, Le Roch K. Nascent RNA sequencing reveals mechanisms of gene regulation in the human malaria parasite Plasmodium falciparum. Nucleic Acids Res 2017; 45:7825-7840. [PMID: 28531310 PMCID: PMC5737683 DOI: 10.1093/nar/gkx464] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/08/2017] [Accepted: 05/10/2017] [Indexed: 12/18/2022] Open
Abstract
Gene expression in Plasmodium falciparum is tightly regulated to ensure successful propagation of the parasite throughout its complex life cycle. The earliest transcriptomics studies in P. falciparum suggested a cascade of transcriptional activity over the course of the 48-hour intraerythrocytic developmental cycle (IDC); however, the just-in-time transcriptional model has recently been challenged by findings that show the importance of post-transcriptional regulation. To further explore the role of transcriptional regulation, we performed the first genome-wide nascent RNA profiling in P. falciparum. Our findings indicate that the majority of genes are transcribed simultaneously during the trophozoite stage of the IDC and that only a small subset of genes is subject to differential transcriptional timing. RNA polymerase II is engaged with promoter regions prior to this transcriptional burst, suggesting that Pol II pausing plays a dominant role in gene regulation. In addition, we found that the overall transcriptional program during gametocyte differentiation is surprisingly similar to the IDC, with the exception of relatively small subsets of genes. Results from this study suggest that further characterization of the molecular players that regulate stage-specific gene expression and Pol II pausing will contribute to our continuous search for novel antimalarial drug targets.
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MESH Headings
- Animals
- Epigenesis, Genetic
- Gene Expression Profiling
- Gene Expression Regulation, Developmental
- Genes, Protozoan
- Humans
- Malaria, Falciparum/blood
- Malaria, Falciparum/parasitology
- Plasmodium falciparum/genetics
- Plasmodium falciparum/growth & development
- Plasmodium falciparum/pathogenicity
- Promoter Regions, Genetic
- RNA Polymerase II/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Protozoan/genetics
- RNA, Protozoan/metabolism
- Sequence Analysis, RNA
- Transcription, Genetic
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Affiliation(s)
- Xueqing Maggie Lu
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA, USA
| | - Gayani Batugedara
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA, USA
| | - Michael Lee
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA, USA
| | - Jacques Prudhomme
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA, USA
| | - Evelien M. Bunnik
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA, USA
- Department of Microbiology, Immunology and Molecular Genetics, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Karine G. Le Roch
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA, USA
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99
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Gürsoy G, Xu Y, Liang J. Spatial organization of the budding yeast genome in the cell nucleus and identification of specific chromatin interactions from multi-chromosome constrained chromatin model. PLoS Comput Biol 2017; 13:e1005658. [PMID: 28704374 PMCID: PMC5531658 DOI: 10.1371/journal.pcbi.1005658] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 07/27/2017] [Accepted: 06/28/2017] [Indexed: 12/22/2022] Open
Abstract
Nuclear landmarks and biochemical factors play important roles in the organization of the yeast genome. The interaction pattern of budding yeast as measured from genome-wide 3C studies are largely recapitulated by model polymer genomes subject to landmark constraints. However, the origin of inter-chromosomal interactions, specific roles of individual landmarks, and the roles of biochemical factors in yeast genome organization remain unclear. Here we describe a multi-chromosome constrained self-avoiding chromatin model (mC-SAC) to gain understanding of the budding yeast genome organization. With significantly improved sampling of genome structures, both intra- and inter-chromosomal interaction patterns from genome-wide 3C studies are accurately captured in our model at higher resolution than previous studies. We show that nuclear confinement is a key determinant of the intra-chromosomal interactions, and centromere tethering is responsible for the inter-chromosomal interactions. In addition, important genomic elements such as fragile sites and tRNA genes are found to be clustered spatially, largely due to centromere tethering. We uncovered previously unknown interactions that were not captured by genome-wide 3C studies, which are found to be enriched with tRNA genes, RNAPIII and TFIIS binding. Moreover, we identified specific high-frequency genome-wide 3C interactions that are unaccounted for by polymer effects under landmark constraints. These interactions are enriched with important genes and likely play biological roles. The architecture of the cell nucleus and the spatial organization of the genome are important in determining nuclear functions. Single-cell imaging techniques and chromosome conformation capture (3C) based methods have provided a wealth of information on the spatial organization of chromosomes. Here we describe a multi-chromosome ensemble model of chromatin chains for understanding the folding principles of budding yeast genome. By overcoming severe challenges in sampling self-avoiding chromatin chains in nuclear confinement, we succeed in generating a large number of model genomes of budding yeast. Our model predicts chromatin interactions that have good correlation with experimental measurements. Our results showed that the spatial confinement of cell nucleus and excluded-volume effect are key determinants of the folding behavior of yeast chromosomes, and largely account for the observed intra-chromosomal interactions. Furthermore, we determined the specific roles of individual nuclear landmarks and biochemical factors, and our analysis showed that centromere tethering largely determines inter-chromosomal interactions. In addition, we were able to infer biological properties from the organization of modeled genomes. We found that the spatial locations of important elements such as fragile sites and tRNA genes are largely determined by the tethering of centromeres to the Spindle Pole Body. We further showed that many of these spatial locations can be predicted by using the genomic distances to the centromeres. Overall, our results revealed important insight into the organizational principles of the budding yeast genome and predicted a number of important biological findings that are fully experimentally testable.
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Affiliation(s)
- Gamze Gürsoy
- The Richard and Loan Hill Department of Bioengineering, Program in Bioinformatics, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Yun Xu
- The Richard and Loan Hill Department of Bioengineering, Program in Bioinformatics, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Jie Liang
- The Richard and Loan Hill Department of Bioengineering, Program in Bioinformatics, University of Illinois at Chicago, Chicago, Illinois, United States of America
- * E-mail:
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100
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Fatakia SN, Kulashreshtha M, Mehta IS, Rao BJ. Chromosome territory relocation paradigm during DNA damage response: Some insights from molecular biology to physics. Nucleus 2017. [PMID: 28640660 DOI: 10.1080/19491034.2017.1313938] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Among the many facets of DNA damage response (DDR), relocation of chromosome territories (CTs) is most intriguing. We have previously reported that cisplatin induced DDR in human dermal fibroblasts led to relocation of CTs 12, 15 from the nuclear periphery to its interior while CTs 19, 17 repositioned from the interior to its periphery. Studies of CT relocation remain nascent as we begin unraveling the role of key players in DDR to demonstrate its mechanistic basis. Consolidating our recent reports, we argue that γH2AX-signaling leads to enhanced recruitment of nuclear myosin 1 (NM1) to chromatin, which via its motor function, results in CT repositioning. Next, we invoke a novel systems-level theory that subsumed CTs as pairs, not solo entities, to present the physical basis for plasticity in interphase CT arrangement. Subsequently, we posited that our systems-level theory describes a unified physical basis for non-random positioning of CTs in interphase nuclei across disparate eukaryotes.
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Affiliation(s)
- Sarosh N Fatakia
- a Department of Biological Sciences, Tata Institute of Fundamental Research , Mumbai , Maharashtra , India
| | - Mugdha Kulashreshtha
- a Department of Biological Sciences, Tata Institute of Fundamental Research , Mumbai , Maharashtra , India
| | - Ishita S Mehta
- a Department of Biological Sciences, Tata Institute of Fundamental Research , Mumbai , Maharashtra , India.,b UM-DAE Centre for Excellence in Basic Sciences, Biological Sciences, Kalina Campus, Santacruz (E) , Mumbai , Maharashtra , India
| | - Basuthkar J Rao
- a Department of Biological Sciences, Tata Institute of Fundamental Research , Mumbai , Maharashtra , India
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