551
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Endogenous Retroviruses Activity as a Molecular Signature of Neurodevelopmental Disorders. Int J Mol Sci 2019; 20:ijms20236050. [PMID: 31801288 PMCID: PMC6928979 DOI: 10.3390/ijms20236050] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Revised: 11/26/2019] [Accepted: 11/28/2019] [Indexed: 12/20/2022] Open
Abstract
Human endogenous retroviruses (HERVs) are genetic elements resulting from relics of ancestral infection of germline cells, now recognized as cofactors in the etiology of several complex diseases. Here we present a review of findings supporting the role of the abnormal HERVs activity in neurodevelopmental disorders. The derailment of brain development underlies numerous neuropsychiatric conditions, likely starting during prenatal life and carrying on during subsequent maturation of the brain. Autism spectrum disorders, attention deficit hyperactivity disorders, and schizophrenia are neurodevelopmental disorders that arise clinically during early childhood or adolescence, currently attributed to the interplay among genetic vulnerability, environmental risk factors, and maternal immune activation. The role of HERVs in human embryogenesis, their intrinsic responsiveness to external stimuli, and the interaction with the immune system support the involvement of HERVs in the derailed neurodevelopmental process. Although definitive proofs that HERVs are involved in neurobehavioral alterations are still lacking, both preclinical models and human studies indicate that the abnormal expression of ERVs could represent a neurodevelopmental disorders-associated biological trait in affected individuals and their parents.
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552
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Fontana S, Chang NC, Chang T, Lee CC, Dang VD, Wang J. The fire ant social supergene is characterized by extensive gene and transposable element copy number variation. Mol Ecol 2019; 29:105-120. [PMID: 31736148 DOI: 10.1111/mec.15308] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 10/31/2019] [Accepted: 11/06/2019] [Indexed: 01/10/2023]
Abstract
In the fire ant Solenopsis invicta, a supergene composed of ~600 genes and having two variants, SB and Sb, regulates colony social form. In single queen colonies, all individuals carry only the SB allele, while in multiple queen colonies, some individuals carry the Sb allele. In this study, we characterized genes with copy number variation between SB and Sb-carrying individuals. We showed extensive acquisition of gene duplicates in the Sb genome, with some likely involved in polygyne-related phenotypes. We found 260 genes with copy number differences between SB and Sb, of which 239 have greater copy number in Sb. We observed transposable element (TE) accumulation on Sb, likely due to the accumulation of repetitive elements on the nonrecombining chromosome. We found a weak correlation between TE copy number and differential expression, suggesting some TEs may still be proliferating in Sb while many of the duplicated TEs have presumably been silenced. Among the 115 non-TE genes with higher copy in Sb, enzymes responsible for cuticular hydrocarbon synthesis were highly represented. These include a desaturase and an elongase, both potentially responsible for differential queen odour and likely beneficial for polygyne ants. These genes seem to have translocated into the supergene from other chromosomes and proliferated by multiple duplication events. While the presence of TEs in supergenes is well documented, little is known about duplication of non-TE genes and their possible adaptive role. Overall, our results suggest that gene duplications may be an important factor leading to monogyne and polygyne ant societies.
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Affiliation(s)
- Silvia Fontana
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.,Biodiversity Taiwan International Graduate Program, Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.,Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - Ni-Chen Chang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Tiffany Chang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Chih-Chi Lee
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Viet-Dai Dang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.,Biodiversity Taiwan International Graduate Program, Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.,Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
| | - John Wang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
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553
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Bao Y, Hu G, Grover CE, Conover J, Yuan D, Wendel JF. Unraveling cis and trans regulatory evolution during cotton domestication. Nat Commun 2019; 10:5399. [PMID: 31776348 PMCID: PMC6881400 DOI: 10.1038/s41467-019-13386-w] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 11/06/2019] [Indexed: 12/12/2022] Open
Abstract
Cis and trans regulatory divergence underlies phenotypic and evolutionary diversification. Relatively little is understood about the complexity of regulatory evolution accompanying crop domestication, particularly for polyploid plants. Here, we compare the fiber transcriptomes between wild and domesticated cotton (Gossypium hirsutum) and their reciprocal F1 hybrids, revealing genome-wide (~15%) and often compensatory cis and trans regulatory changes under divergence and domestication. The high level of trans evolution (54%-64%) observed is likely enabled by genomic redundancy following polyploidy. Our results reveal that regulatory variation is significantly associated with sequence evolution, inheritance of parental expression patterns, co-expression gene network properties, and genomic loci responsible for domestication traits. With respect to regulatory evolution, the two subgenomes of allotetraploid cotton are often uncoupled. Overall, our work underscores the complexity of regulatory evolution during fiber domestication and may facilitate new approaches for improving cotton and other polyploid plants.
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Affiliation(s)
- Ying Bao
- School of Life Sciences, Qufu Normal University, 273165, Qufu, Shandong Province, China.
| | - Guanjing Hu
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
| | - Corrinne E Grover
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
| | - Justin Conover
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
| | - Daojun Yuan
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
| | - Jonathan F Wendel
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA, 50011, USA.
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554
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Bell CG, Lowe R, Adams PD, Baccarelli AA, Beck S, Bell JT, Christensen BC, Gladyshev VN, Heijmans BT, Horvath S, Ideker T, Issa JPJ, Kelsey KT, Marioni RE, Reik W, Relton CL, Schalkwyk LC, Teschendorff AE, Wagner W, Zhang K, Rakyan VK. DNA methylation aging clocks: challenges and recommendations. Genome Biol 2019; 20:249. [PMID: 31767039 PMCID: PMC6876109 DOI: 10.1186/s13059-019-1824-y] [Citation(s) in RCA: 455] [Impact Index Per Article: 91.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 09/16/2019] [Indexed: 12/15/2022] Open
Abstract
Epigenetic clocks comprise a set of CpG sites whose DNA methylation levels measure subject age. These clocks are acknowledged as a highly accurate molecular correlate of chronological age in humans and other vertebrates. Also, extensive research is aimed at their potential to quantify biological aging rates and test longevity or rejuvenating interventions. Here, we discuss key challenges to understand clock mechanisms and biomarker utility. This requires dissecting the drivers and regulators of age-related changes in single-cell, tissue- and disease-specific models, as well as exploring other epigenomic marks, longitudinal and diverse population studies, and non-human models. We also highlight important ethical issues in forensic age determination and predicting the trajectory of biological aging in an individual.
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Affiliation(s)
- Christopher G Bell
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
| | - Robert Lowe
- The Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
| | - Peter D Adams
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
- Beatson Institute for Cancer Research and University of Glasgow, Glasgow, UK.
| | - Andrea A Baccarelli
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA.
| | - Stephan Beck
- Medical Genomics, Paul O'Gorman Building, UCL Cancer Institute, University College London, London, UK.
| | - Jordana T Bell
- Department of Twin Research and Genetic Epidemiology, King's College London, London, UK.
| | - Brock C Christensen
- Department of Epidemiology, Geisel School of Medicine, Dartmouth College, Lebanon, NH, USA.
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Lebanon, NH, USA.
- Department of Community and Family Medicine, Geisel School of Medicine, Dartmouth College, Lebanon, NH, USA.
| | - Vadim N Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
| | - Bastiaan T Heijmans
- Molecular Epidemiology, Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, the Netherlands.
| | - Steve Horvath
- Department of Human Genetics, Gonda Research Center, David Geffen School of Medicine, Los Angeles, CA, USA.
- Department of Biostatistics, School of Public Health, University of California-Los Angeles, Los Angeles, CA, USA.
| | - Trey Ideker
- San Diego Center for Systems Biology, University of California-San Diego, San Diego, CA, USA.
| | - Jean-Pierre J Issa
- Fels Institute for Cancer Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA.
| | - Karl T Kelsey
- Department of Epidemiology, Brown University, Providence, RI, USA.
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, USA.
| | - Riccardo E Marioni
- Centre for Genomic and Experimental Medicine, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK.
- Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, Edinburgh, UK.
| | - Wolf Reik
- Epigenetics Programme, The Babraham Institute, Cambridge, UK.
- The Wellcome Trust Sanger Institute, Cambridge, UK.
| | - Caroline L Relton
- Medical Research Council Integrative Epidemiology Unit (MRC IEU), School of Social and Community Medicine, University of Bristol, Bristol, UK.
| | | | - Andrew E Teschendorff
- CAS Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, 200031, China.
- UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6BT, UK.
| | - Wolfgang Wagner
- Helmholtz-Institute for Biomedical Engineering, Stem Cell Biology and Cellular Engineering, RWTH Aachen Faculty of Medicine, Aachen, Germany.
| | - Kang Zhang
- Faculty of Medicine, Macau University of Science and Technology, Taipa, Macau.
| | - Vardhman K Rakyan
- The Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
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555
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Purcell J, Pruitt JN. Are personalities genetically determined? Inferences from subsocial spiders. BMC Genomics 2019; 20:867. [PMID: 31752670 PMCID: PMC6873478 DOI: 10.1186/s12864-019-6172-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 10/02/2019] [Indexed: 11/25/2022] Open
Abstract
Background Recent research has revealed that polymorphic behavioral strategies shape intra-and interspecific interactions and contribute to fitness in many animal species. A better understanding of the proximate mechanisms underlying these behavioral syndromes will enhance our grasp this phenomenon. Spiders in the genus Anelosimus exhibit inter-individual behavioral variation on several axes: individuals have consistent responses to stimuli (e.g. bold vs. shy individuals) and they are subsocial (exhibiting extended maternal care and sibling cooperation) across most of their range, but they sometimes form permanent social groups in northern temperate regions. Here, we seek genetic variants associated with boldness and with social structure in a socially polymorphic population of the spider Anelosimus studiosus. We also develop preliminary genomic resources, including a genome assembly and linkage map, that support this and future genomic research on this group. Results Remarkably, we identify a small genomic scaffold (~ 1200 bp) that harbors seven single nucleotide polymorphisms (SNPs) associated with boldness. Moreover, heterozygotes are less common than expected based on Hardy-Weinberg equilibrium, suggesting that either assortative mating or selection against heterozygotes may be occurring in this system. We find no loci significantly associated with social organization. Our draft genome assembly allows us to localize SNPs of interest in this study and to carry out genetic comparisons with other published genomes, although it remains highly fragmented. Conclusions By identifying a locus associated with a well-studied animal personality trait, this study opens up avenues for future research to link behavioral studies of animal personality with genotype and fitness.
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Affiliation(s)
- Jessica Purcell
- Department of Entomology, University of California Riverside, 900 University Ave, Riverside, CA, 92521, USA.
| | - Jonathan N Pruitt
- Department of Psychology, Neuroscience and Behaviour, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
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556
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Transposable element expression in tumors is associated with immune infiltration and increased antigenicity. Nat Commun 2019; 10:5228. [PMID: 31745090 PMCID: PMC6864081 DOI: 10.1038/s41467-019-13035-2] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 10/15/2019] [Indexed: 12/19/2022] Open
Abstract
Profound global loss of DNA methylation is a hallmark of many cancers. One potential consequence of this is the reactivation of transposable elements (TEs) which could stimulate the immune system via cell-intrinsic antiviral responses. Here, we develop REdiscoverTE, a computational method for quantifying genome-wide TE expression in RNA sequencing data. Using The Cancer Genome Atlas database, we observe increased expression of over 400 TE subfamilies, of which 262 appear to result from a proximal loss of DNA methylation. The most recurrent TEs are among the evolutionarily youngest in the genome, predominantly expressed from intergenic loci, and associated with antiviral or DNA damage responses. Treatment of glioblastoma cells with a demethylation agent results in both increased TE expression and de novo presentation of TE-derived peptides on MHC class I molecules. Therapeutic reactivation of tumor-specific TEs may synergize with immunotherapy by inducing inflammation and the display of potentially immunogenic neoantigens. Treatment with demethylation agents can reactivate transposable elements. Here in glioblastoma, the authors also show that this is accompanied by de novo presentation of TE-derived peptides on MHC class I molecules.
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557
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Fan Y, Ye MS, Zhang JY, Xu L, Yu DD, Gu TL, Yao YL, Chen JQ, Lv LB, Zheng P, Wu DD, Zhang GJ, Yao YG. Chromosomal level assembly and population sequencing of the Chinese tree shrew genome. Zool Res 2019; 40:506-521. [PMID: 31418539 PMCID: PMC6822927 DOI: 10.24272/j.issn.2095-8137.2019.063] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 08/09/2019] [Indexed: 01/11/2023] Open
Abstract
Chinese tree shrews (Tupaia belangeri chinensis) have become an increasingly important experimental animal in biomedical research due to their close relationship to primates. An accurately sequenced and assembled genome is essential for understanding the genetic features and biology of this animal. In this study, we used long-read single-molecule sequencing and high-throughput chromosome conformation capture (Hi-C) technology to obtain a high-qualitychromosome-scale scaffolding of the Chinese tree shrew genome. The new reference genome (KIZ version 2: TS_2.0) resolved problems in presently available tree shrew genomes and enabled accurate identification of large and complex repeat regions, gene structures, and species-specific genomic structural variants. In addition, by sequencing the genomes of six Chinese tree shrew individuals, we produced a comprehensive map of 12.8 M single nucleotide polymorphisms and confirmed that the major histocompatibility complex (MHC) loci and immunoglobulin gene family exhibited high nucleotide diversity in the tree shrew genome. We updated the tree shrew genome database (TreeshrewDB v2.0: http://www.treeshrewdb.org) to include the genome annotation information and genetic variations. The new high-quality reference genome of the Chinese tree shrew and the updated TreeshrewDB will facilitate the use of this animal in many different fields of research.
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Affiliation(s)
- Yu Fan
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Mao-Sen Ye
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming Yunnan 650204, China
| | - Jin-Yan Zhang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming Yunnan 650204, China
| | - Ling Xu
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Dan-Dan Yu
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Tian-Le Gu
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming Yunnan 650204, China
| | - Yu-Lin Yao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming Yunnan 650204, China
| | - Jia-Qi Chen
- Kunming Primate Research Center of the Chinese Academy of Sciences, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Long-Bao Lv
- Kunming Primate Research Center of the Chinese Academy of Sciences, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Ping Zheng
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming Yunnan 650204, China
- Kunming Primate Research Center of the Chinese Academy of Sciences, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- Yunnan Key Laboratory of Animal Reproduction, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Dong-Dong Wu
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Guo-Jie Zhang
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
| | - Yong-Gang Yao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China, E-mail:
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming Yunnan 650204, China
- Kunming Primate Research Center of the Chinese Academy of Sciences, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
- KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming Yunnan 650223, China
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558
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Lv Y, Hu F, Zhou Y, Wu F, Gaut BS. Maize transposable elements contribute to long non-coding RNAs that are regulatory hubs for abiotic stress response. BMC Genomics 2019; 20:864. [PMID: 31729949 PMCID: PMC6858665 DOI: 10.1186/s12864-019-6245-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 10/30/2019] [Indexed: 02/07/2023] Open
Abstract
Background Several studies have mined short-read RNA sequencing datasets to identify long non-coding RNAs (lncRNAs), and others have focused on the function of individual lncRNAs in abiotic stress response. However, our understanding of the complement, function and origin of lncRNAs – and especially transposon derived lncRNAs (TE-lncRNAs) - in response to abiotic stress is still in its infancy. Results We utilized a dataset of 127 RNA sequencing samples that included total RNA datasets and PacBio fl-cDNA data to discover lncRNAs in maize. Overall, we identified 23,309 candidate lncRNAs from polyA+ and total RNA samples, with a strong discovery bias within total RNA. The majority (65%) of the 23,309 lncRNAs had sequence similarity to transposable elements (TEs). Most had similarity to long-terminal-repeat retrotransposons from the Copia and Gypsy superfamilies, reflecting a high proportion of these elements in the genome. However, DNA transposons were enriched for lncRNAs relative to their genomic representation by ~ 2-fold. By assessing the fraction of lncRNAs that respond to abiotic stresses like heat, cold, salt and drought, we identified 1077 differentially expressed lncRNA transcripts, including 509 TE-lncRNAs. In general, the expression of these lncRNAs was significantly correlated with their nearest gene. By inferring co-expression networks across our large dataset, we found that 39 lncRNAs are as major hubs in co-expression networks that respond to abiotic stress, and 18 appear to be derived from TEs. Conclusions Our results show that lncRNAs are enriched in total RNA samples, that most (65%) are derived from TEs, that at least 1077 are differentially expressed during abiotic stress, and that 39 are hubs in co-expression networks, including a small number that are evolutionary conserved. These results suggest that lncRNAs, including TE-lncRNAs, may play key regulatory roles in moderating abiotic responses.
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Affiliation(s)
- Yuanda Lv
- Provincial Key Laboratory of Agrobiology, Institute of Crop Germplasm and Biotechnology, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,Department of Ecology and Evolutionary, Biology, UC Irvine, Irvine, CA, USA
| | - Fengqin Hu
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Yongfeng Zhou
- Department of Ecology and Evolutionary, Biology, UC Irvine, Irvine, CA, USA
| | - Feilong Wu
- Department of Civil and Environmental, Engineering, UC Irvine, Irvine, CA, USA
| | - Brandon S Gaut
- Department of Ecology and Evolutionary, Biology, UC Irvine, Irvine, CA, USA.
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559
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Expansion of LINEs and species-specific DNA repeats drives genome expansion in Asian Gypsy Moths. Sci Rep 2019; 9:16413. [PMID: 31712581 PMCID: PMC6848174 DOI: 10.1038/s41598-019-52840-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 10/18/2019] [Indexed: 01/16/2023] Open
Abstract
Two subspecies of Asian gypsy moth (AGM), Lymantria dispar asiatica and L. dispar japonica, pose a serious alien invasive threat to North American forests. Despite decades of research on the ecology and biology of this pest, limited AGM-specific genomic resources are currently available. Here, we report on the genome sequences and functional content of these AGM subspecies. The genomes of L.d. asiatica and L.d. japonica are the largest lepidopteran genomes sequenced to date, totaling 921 and 999 megabases, respectively. Large genome size in these subspecies is driven by the accumulation of specific classes of repeats. Genome-wide metabolic pathway reconstructions suggest strong genomic signatures of energy-related pathways in both subspecies, dominated by metabolic functions related to thermogenesis. The genome sequences reported here will provide tools for probing the molecular mechanisms underlying phenotypic traits that are thought to enhance AGM invasiveness.
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560
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Wu B, Cox MP. Greater genetic and regulatory plasticity of retained duplicates in Epichloë endophytic fungi. Mol Ecol 2019; 28:5103-5114. [PMID: 31614039 PMCID: PMC7004115 DOI: 10.1111/mec.15275] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 10/11/2019] [Indexed: 12/12/2022]
Abstract
Gene duplicates can act as a source of genetic material from which new functions arise. Most duplicated genes revert to single copy genes and only a small proportion are retained. However, it remains unclear why some duplicate genes persist in the genome for an extended time. We investigate this question by analysing retained gene duplicates in the fungal genus Epichloë, ascomycete fungi that form close endophytic symbioses with their host grasses. Retained duplicates within this genus have two independent origins, but both long pre-date the origin and diversification of the genus Epichloë. We find that loss of retained duplicates within the genus is frequent and often associated with speciation. Retained duplicates have faster evolutionary rates (Ka) and show relaxed selection (Ka/Ks) compared to single copy genes. Both features are time-dependent. Through comparison of conspecific strains, we find greater evolutionary rates in coding regions and sequence divergence in regulatory regions of retained duplicates than single copy genes, with this pattern more pronounced for strains adapted to different grass host species. Consistent with this sequence divergence in regulatory regions, transcriptome analyses show greater expression variation of retained duplicates than single copy genes. This suggest that cis-regulatory changes make important contributions to the expression patterns of retained duplicates. Coupled with supporting observations from the model yeast Saccharomyces cerevisiae, these data suggest that genetic robustness and regulatory plasticity are common drivers behind the retention of duplicated genes in fungi.
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Affiliation(s)
- Baojun Wu
- Statistics and Bioinformatics Group, School of Fundamental Sciences, Massey University, Palmerston North, New Zealand.,Bio-Protection Research Centre, Massey University, Palmerston North, New Zealand
| | - Murray P Cox
- Statistics and Bioinformatics Group, School of Fundamental Sciences, Massey University, Palmerston North, New Zealand.,Bio-Protection Research Centre, Massey University, Palmerston North, New Zealand
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561
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Abstract
Pongamia pinnata (also called Millettia pinnata), a non-edible oil yielding tree, is well known for its multipurpose benefits and acts as a potential source for medicine and biodiesel preparation. Due to increase in demand for cultivation, understanding of genetic diversity is an important parameter for further breeding and cultivation programme. Transposable elements (TEs) are a major component of plant genome but still, their evolutionary significance in Pongamia remains unexplored. In view to understand the role of TEs in genome diversity, Pongamia unigenes were screened for the presence of TE cassettes. Our analysis showed the presence of all categories of TE cassettes in unigenes with major contribution of long terminal repeat-retrotransposons towards unigene diversity. Interestingly, the insertion of some TEs was also observed in both organellar genomes. The study of insertion of TEs in coding sequence is of great interest as they may be responsible for protein diversity thereby influencing the phenotype. The present investigation confirms the exaptation phenomenon in pyruvate decarboxylase (PDC) gene where the entire exon sequence was derived from Ty3-gypsy like retrotransposon. The study of PDC protein revealed the translation of gypsy element into protein. Furthermore, the phylogenetic study confirmed the diversity in PDC gene due to insertion of the gypsy element, where the PDC genes with and without gypsy insertion were clustered separately.
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Affiliation(s)
- Rahul G Shelke
- Applied Biodiversity Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam, 781 039, India
| | - Latha Rangan
- Applied Biodiversity Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam, 781 039, India.
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562
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Osipova E, Hecker N, Hiller M. RepeatFiller newly identifies megabases of aligning repetitive sequences and improves annotations of conserved non-exonic elements. Gigascience 2019; 8:giz132. [PMID: 31742600 PMCID: PMC6862929 DOI: 10.1093/gigascience/giz132] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/10/2019] [Accepted: 10/15/2019] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Transposons and other repetitive sequences make up a large part of complex genomes. Repetitive sequences can be co-opted into a variety of functions and thus provide a source for evolutionary novelty. However, comprehensively detecting ancestral repeats that align between species is difficult because considering all repeat-overlapping seeds in alignment methods that rely on the seed-and-extend heuristic results in prohibitively high runtimes. RESULTS Here, we show that ignoring repeat-overlapping alignment seeds when aligning entire genomes misses numerous alignments between repetitive elements. We present a tool, RepeatFiller, that improves genome alignments by incorporating previously undetected local alignments between repetitive sequences. By applying RepeatFiller to genome alignments between human and 20 other representative mammals, we uncover between 22 and 84 Mb of previously undetected alignments that mostly overlap transposable elements. We further show that the increased alignment coverage improves the annotation of conserved non-exonic elements, both by discovering numerous novel transposon-derived elements that evolve under constraint and by removing thousands of elements that are not under constraint in placental mammals. CONCLUSIONS RepeatFiller contributes to comprehensively aligning repetitive genomic regions, which facilitates studying transposon co-option and genome evolution. Source code: https://github.com/hillerlab/GenomeAlignmentTools.
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Affiliation(s)
- Ekaterina Osipova
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden, Germany
- Center for Systems Biology, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Nikolai Hecker
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden, Germany
- Center for Systems Biology, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Michael Hiller
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden, Germany
- Center for Systems Biology, Pfotenhauerstr. 108, 01307 Dresden, Germany
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563
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Structure of a P element transposase-DNA complex reveals unusual DNA structures and GTP-DNA contacts. Nat Struct Mol Biol 2019; 26:1013-1022. [PMID: 31659330 DOI: 10.1038/s41594-019-0319-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 09/11/2019] [Indexed: 01/19/2023]
Abstract
P element transposase catalyzes the mobility of P element DNA transposons within the Drosophila genome. P element transposase exhibits several unique properties, including the requirement for a guanosine triphosphate cofactor and the generation of long staggered DNA breaks during transposition. To gain insights into these features, we determined the atomic structure of the Drosophila P element transposase strand transfer complex using cryo-EM. The structure of this post-transposition nucleoprotein complex reveals that the terminal single-stranded transposon DNA adopts unusual A-form and distorted B-form helical geometries that are stabilized by extensive protein-DNA interactions. Additionally, we infer that the bound guanosine triphosphate cofactor interacts with the terminal base of the transposon DNA, apparently to position the P element DNA for catalysis. Our structure provides the first view of the P element transposase superfamily, offers new insights into P element transposition and implies a transposition pathway fundamentally distinct from other cut-and-paste DNA transposases.
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564
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Evolution and diversity of transposable elements in fish genomes. Sci Rep 2019; 9:15399. [PMID: 31659260 PMCID: PMC6817897 DOI: 10.1038/s41598-019-51888-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 10/09/2019] [Indexed: 12/22/2022] Open
Abstract
Transposable elements (TEs) are genomic sequences that can move, multiply, and often form sizable fractions of vertebrate genomes. Fish belong to a unique group of vertebrates, since their karyotypes and genome sizes are more diverse and complex, with probably higher diversity and evolution specificity of TE. To investigate the characteristics of fish TEs, we compared the mobilomes of 39 species, and observed significant variation of TE content in fish (from 5% in pufferfish to 56% in zebrafish), along with a positive correlation between fish genome size and TE content. In different classification hierarchies, retrotransposons (class), long terminal repeat (order), as well as Helitron, Maverick, Kolobok, CMC, DIRS, P, I, L1, L2, and 5S (superfamily) were all positively correlated with fish genome size. Consistent with previous studies, our data suggested fish genomes to not always be dominated by DNA transposons; long interspersed nuclear elements are also prominent in many species. This study suggests CR1 distribution in fish genomes to be obviously regular, and provides new clues concerning important events in vertebrate evolution. Altogether, our results highlight the importance of TEs in the structure and evolution of fish genomes and suggest fish species diversity to parallel transposon content diversification.
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565
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Cordeiro J, Carvalho TL, Valente VLDS, Robe LJ. Evolutionary history and classification of Micropia retroelements in Drosophilidae species. PLoS One 2019; 14:e0220539. [PMID: 31622354 PMCID: PMC6797199 DOI: 10.1371/journal.pone.0220539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 10/04/2019] [Indexed: 11/19/2022] Open
Abstract
Transposable elements (TEs) have the main role in shaping the evolution of genomes and host species, contributing to the creation of new genes and promoting rearrangements frequently associated with new regulatory networks. Support for these hypotheses frequently results from studies with model species, and Drosophila provides a great model organism to the study of TEs. Micropia belongs to the Ty3/Gypsy group of long terminal repeats (LTR) retroelements and comprises one of the least studied Drosophila transposable elements. In this study, we assessed the evolutionary history of Micropia within Drosophilidae, while trying to assist in the classification of this TE. At first, we performed searches of Micropia presence in the genome of natural populations from several species. Then, based on searches within online genomic databases, we retrieved Micropia-like sequences from the genomes of distinct Drosophilidae species. We expanded the knowledge of Micropia distribution within Drosophila species. The Micropia retroelements we detected consist of an array of divergent sequences, which we subdivided into 20 subfamilies. Even so, a patchy distribution of Micropia sequences within the Drosophilidae phylogeny could be identified, with incongruences between the species phylogeny and the Micropia phylogeny. Comparing the pairwise synonymous distance (dS) values between Micropia and three host nuclear sequences, we found several cases of unexpectedly high levels of similarity between Micropia sequences in divergent species. All these findings provide a hypothesis to the evolution of Micropia within Drosophilidae, which include several events of vertical and horizontal transposon transmission, associated with ancestral polymorphisms and recurrent Micropia sequences diversification.
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Affiliation(s)
- Juliana Cordeiro
- Departamento de Ecologia, Zoologia e Genética, Instituto de Biologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil
| | - Tuane Letícia Carvalho
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Vera Lúcia da Silva Valente
- Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre; Rio Grande do Sul; Brazil
| | - Lizandra Jaqueline Robe
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
- Departamento de Ecologia e Evolução, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
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566
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Yang WR, Ardeljan D, Pacyna CN, Payer LM, Burns KH. SQuIRE reveals locus-specific regulation of interspersed repeat expression. Nucleic Acids Res 2019; 47:e27. [PMID: 30624635 PMCID: PMC6411935 DOI: 10.1093/nar/gky1301] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 12/18/2018] [Accepted: 01/03/2019] [Indexed: 12/13/2022] Open
Abstract
Transposable elements (TEs) are interspersed repeat sequences that make up much of the human genome. Their expression has been implicated in development and disease. However, TE-derived RNA-seq reads are difficult to quantify. Past approaches have excluded these reads or aggregated RNA expression to subfamilies shared by similar TE copies, sacrificing quantitative accuracy or the genomic context necessary to understand the basis of TE transcription. As a result, the effects of TEs on gene expression and associated phenotypes are not well understood. Here, we present Software for Quantifying Interspersed Repeat Expression (SQuIRE), the first RNA-seq analysis pipeline that provides a quantitative and locus-specific picture of TE expression (https://github.com/wyang17/SQuIRE). SQuIRE is an accurate and user-friendly tool that can be used for a variety of species. We applied SQuIRE to RNA-seq from normal mouse tissues and a Drosophila model of amyotrophic lateral sclerosis. In both model organisms, we recapitulated previously reported TE subfamily expression levels and revealed locus-specific TE expression. We also identified differences in TE transcription patterns relating to transcript type, gene expression and RNA splicing that would be lost with other approaches using subfamily-level analyses. Altogether, our findings illustrate the importance of studying TE transcription with locus-level resolution.
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Affiliation(s)
- Wan R Yang
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Daniel Ardeljan
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,McKusick-Nathans Institute of Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Clarissa N Pacyna
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Lindsay M Payer
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Kathleen H Burns
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,McKusick-Nathans Institute of Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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567
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Kaján GL, Doszpoly A, Tarján ZL, Vidovszky MZ, Papp T. Virus-Host Coevolution with a Focus on Animal and Human DNA Viruses. J Mol Evol 2019; 88:41-56. [PMID: 31599342 PMCID: PMC6943099 DOI: 10.1007/s00239-019-09913-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 09/23/2019] [Indexed: 01/21/2023]
Abstract
Viruses have been infecting their host cells since the dawn of life, and this extremely long-term coevolution gave rise to some surprising consequences for the entire tree of life. It is hypothesised that viruses might have contributed to the formation of the first cellular life form, or that even the eukaryotic cell nucleus originates from an infection by a coated virus. The continuous struggle between viruses and their hosts to maintain at least a constant fitness level led to the development of an unceasing arms race, where weapons are often shuttled between the participants. In this literature review we try to give a short insight into some general consequences or traits of virus–host coevolution, and after this we zoom in to the viral clades of adenoviruses, herpesviruses, nucleo-cytoplasmic large DNA viruses, polyomaviruses and, finally, circoviruses.
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Affiliation(s)
- Győző L Kaján
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Hungária krt. 21, Budapest, 1143, Hungary.
| | - Andor Doszpoly
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Hungária krt. 21, Budapest, 1143, Hungary
| | - Zoltán László Tarján
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Hungária krt. 21, Budapest, 1143, Hungary
| | - Márton Z Vidovszky
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Hungária krt. 21, Budapest, 1143, Hungary
| | - Tibor Papp
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Hungária krt. 21, Budapest, 1143, Hungary
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568
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Jung S, Venkatesh J, Kang MY, Kwon JK, Kang BC. A non-LTR retrotransposon activates anthocyanin biosynthesis by regulating a MYB transcription factor in Capsicum annuum. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 287:110181. [PMID: 31481212 DOI: 10.1016/j.plantsci.2019.110181] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 06/24/2019] [Accepted: 06/28/2019] [Indexed: 05/20/2023]
Abstract
The flavonoid compound anthocyanin is an important plant metabolite with nutritional and aesthetic value as well as anti-oxidative capacity. MYB transcription factors are key regulators of anthocyanin biosynthesis in plants. In pepper (Capsicum annuum), the CaAn2 gene, encoding an R2R3 MYB transcription factor, regulates anthocyanin biosynthesis. However, no functional study or structural analysis of functional and dysfunctional CaAn2 alleles has been performed. Here, to elucidate the function of CaAn2, we generated transgenic Nicotiana benthamiana and Arabidopsis thaliana plants expressing CaAn2. All of the tissues in these plants were purple. Promoter analysis of CaAn2 in purple C. annuum 'KC00134' plants revealed the insertion of a non-long terminal repeat (LTR) retrotransposon designated Ca-nLTR-A. To determine the promoter activity and functional domain of Ca-nLTR-A, various constructs carrying different domains of Ca-nLTR-A fused with GUS were transformed into N. benthamiana. Promoter analysis showed that the 3' untranslated region (UTR) of the second open reading frame of Ca-nLTR-A is responsible for CaAn2 expression in 'KC00134'. Sequence analysis of Ca-nLTR-A identified transcription factor binding sites known to regulate anthocyanin biosynthesis. This study indicates that insertion of a non-LTR retrotransposon in the promoter may activate expression of CaAn2 by recruiting transcription factors at the 3' UTR and thus provides the first example of exaptation of a non-LTR retrotransposon into a new promoter in plants.
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Affiliation(s)
- Soyoung Jung
- Department of Plant Science, Plant Genomics & Breeding Institute, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea.
| | - Jelli Venkatesh
- Department of Plant Science, Plant Genomics & Breeding Institute, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea.
| | - Min-Young Kang
- Department of Plant Science, Plant Genomics & Breeding Institute, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea.
| | - Jin-Kyung Kwon
- Department of Plant Science, Plant Genomics & Breeding Institute, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea.
| | - Byoung-Cheorl Kang
- Department of Plant Science, Plant Genomics & Breeding Institute, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea.
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569
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Abstract
The evolutionary processes that transitioned plants to land-based habitats also incorporated a multiplicity of strategies to enhance resilience to the greater environmental variation encountered on land. The sensing of light, its quality, quantity, and duration, is central to plant survival and, as such, serves as a central network hub. Similarly, plants as sessile organisms that can encounter isolation must continually assess their reproductive options, requiring plasticity in propagation by self- and cross-pollination or asexual strategies. Irregular fluctuations and intermittent extremes in temperature, soil fertility, and moisture conditions have given impetus to genetic specializations for network resiliency, protein neofunctionalization, and internal mechanisms to accelerate their evolution. We review some of the current advancements made in understanding plant resiliency and phenotypic plasticity mechanisms. These mechanisms incorporate unusual nuclear-cytoplasmic interactions, various transposable element (TE) activities, and epigenetic plasticity of central gene networks that are broadly pleiotropic to influence resiliency phenotypes.
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Affiliation(s)
- Xiaodong Yang
- Departments of Biology and Plant Science, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Sally A Mackenzie
- Departments of Biology and Plant Science, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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570
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Lea JK, Unckless RL. An assessment of the immune costs associated with meiotic drive elements in Drosophila. Proc Biol Sci 2019; 286:20191534. [PMID: 31530140 PMCID: PMC6784720 DOI: 10.1098/rspb.2019.1534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 08/28/2019] [Indexed: 12/13/2022] Open
Abstract
Most organisms are constantly adapting to pathogens and parasites that exploit their host for their own benefit. Less studied, but perhaps more ubiquitous, are intragenomic parasites or selfish genetic elements. These include transposable elements, selfish B chromosomes and meiotic drivers that promote their own replication without regard to fitness effects on hosts. Therefore, intragenomic parasites are also a constant evolutionary pressure on hosts. Gamete-killing meiotic drive elements are often associated with large chromosomal inversions that reduce recombination between the drive and wild-type chromosomes. This reduced recombination is thought to reduce the efficacy of selection on the drive chromosome and allow for the accumulation of deleterious mutations. We tested whether gamete-killing meiotic drive chromosomes were associated with reduced immune defence against two bacterial pathogens in three species of Drosophila. We found little evidence of reduced immune defence in lines with meiotic drive. One line carrying the Drosophila melanogaster autosomal Segregation Distorter did show reduced defence, but we were unable to attribute that reduced defence to either genotype or immune gene expression differences. Our results suggest that though gamete-killing meiotic drive chromosomes probably accumulate deleterious mutations, those mutations do not result in reduced capacity for immune defence.
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Affiliation(s)
| | - Robert L. Unckless
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA
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571
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Stewart NB, Rogers RL. Chromosomal rearrangements as a source of new gene formation in Drosophila yakuba. PLoS Genet 2019; 15:e1008314. [PMID: 31545792 PMCID: PMC6776367 DOI: 10.1371/journal.pgen.1008314] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 10/03/2019] [Accepted: 07/17/2019] [Indexed: 11/19/2022] Open
Abstract
The origins of new genes are among the most fundamental questions in evolutionary biology. Our understanding of the ways that new genetic material appears and how that genetic material shapes population variation remains incomplete. De novo genes and duplicate genes are a key source of new genetic material on which selection acts. To better understand the origins of these new gene sequences, we explored the ways that structural variation might alter expression patterns and form novel transcripts. We provide evidence that chromosomal rearrangements are a source of novel genetic variation that facilitates the formation of de novo exons in Drosophila. We identify 51 cases of de novo exon formation created by chromosomal rearrangements in 14 strains of D. yakuba. These new genes inherit transcription start signals and open reading frames when the 5' end of existing genes are combined with previously untranscribed regions. Such new genes would appear with novel peptide sequences, without the necessity for secondary transitions from non-coding RNA to protein. This mechanism of new peptide formations contrasts with canonical theory of de novo gene progression requiring non-coding intermediaries that must acquire new mutations prior to loss via pseudogenization. Hence, these mutations offer a means to de novo gene creation and protein sequence formation in a single mutational step, answering a long standing open question concerning new gene formation. We further identify gene expression changes to 134 existing genes, indicating that these mutations can alter gene regulation. Population variability for chromosomal rearrangements is considerable, with 2368 rearrangements observed across 14 inbred lines. More rearrangements were identified on the X chromosome than any of the autosomes, suggesting the X is more susceptible to chromosome alterations. Together, these results suggest that chromosomal rearrangements are a source of variation in populations that is likely to be important to explain genetic and therefore phenotypic diversity.
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Affiliation(s)
- Nicholas B. Stewart
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte, North Carolina, United States of America
- Department of Biological Sciences, Ft Hays State University, Ft Hays, Kansas, United States of America
| | - Rebekah L. Rogers
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte, North Carolina, United States of America
- * E-mail:
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572
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Ninova M, Fejes Tóth K, Aravin AA. The control of gene expression and cell identity by H3K9 trimethylation. Development 2019; 146:dev181180. [PMID: 31540910 PMCID: PMC6803365 DOI: 10.1242/dev.181180] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Histone 3 lysine 9 trimethylation (H3K9me3) is a conserved histone modification that is best known for its role in constitutive heterochromatin formation and the repression of repetitive DNA elements. More recently, it has become evident that H3K9me3 is also deposited at certain loci in a tissue-specific manner and plays important roles in regulating cell identity. Notably, H3K9me3 can repress genes encoding silencing factors, pointing to a fundamental principle of repressive chromatin auto-regulation. Interestingly, recent studies have shown that H3K9me3 deposition requires protein SUMOylation in different contexts, suggesting that the SUMO pathway functions as an important module in gene silencing and heterochromatin formation. In this Review, we discuss the role of H3K9me3 in gene regulation in various systems and the molecular mechanisms that guide the silencing machinery to target loci.
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Affiliation(s)
- Maria Ninova
- California Institute of Technology, Division of Biology and Biological Engineering, 147-75, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Katalin Fejes Tóth
- California Institute of Technology, Division of Biology and Biological Engineering, 147-75, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Alexei A Aravin
- California Institute of Technology, Division of Biology and Biological Engineering, 147-75, 1200 East California Boulevard, Pasadena, CA 91125, USA
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573
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Fan C, Wu YH, Decker CM, Rohani R, Gesell Salazar M, Ye H, Cui Z, Schmidt F, Huang WE. Defensive Function of Transposable Elements in Bacteria. ACS Synth Biol 2019; 8:2141-2151. [PMID: 31375026 DOI: 10.1021/acssynbio.9b00218] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
It has been widely debated whether transposable elements have a positive or a negative effect on their host cells. This study demonstrated that transposable elements, specifically insertion sequences (ISs), can adopt a defensive role in Escherichia coli. In three different E. coli strains (S17, DH5α, and Nissle 1917), IS1 and IS10 rapidly disrupted the I-CeuI gene (encoding I-CeuI endonuclease) on the plasmid pLO11-ICeuI as early as the first generation, despite the gene-circuit being under control of an arabinose promoter. Proteomics analysis showed that the protein abundance profile of E. coli DH5α with pLO11-ICeuI in the fifth generation was nearly opposite to that of control strain (E. coli with pLO11, no I-CeuI). The DNA damage caused by the leaky expression of I-CeuI was enough to trigger a SOS response and alter lipid synthesis, ribosomal activity, RNA/DNA metabolism, central dogma and cell cycle processes in E. coli DH5α. After the ISs disrupted the expression of I-CeuI, cells fully recovered by the 31st generation had a protein abundance profile similar to that of the control strain. This study showed that ISs readily mutated a harmful gene which subsequently restored host fitness. These observations have implications for the stability of designed gene circuits in synthetic biology.
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Affiliation(s)
- Catherine Fan
- Department of Engineering Science, University of Oxford, Parks Road, OX1 3PJ Oxford, United Kingdom
| | - Yin-Hu Wu
- Department of Engineering Science, University of Oxford, Parks Road, OX1 3PJ Oxford, United Kingdom
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Christoph M. Decker
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Felix-Hausdorff-Str. 8, 17475 Greifswald, Germany
| | - Reza Rohani
- Department of Engineering Science, University of Oxford, Parks Road, OX1 3PJ Oxford, United Kingdom
| | - Manuela Gesell Salazar
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Felix-Hausdorff-Str. 8, 17475 Greifswald, Germany
| | - Hua Ye
- Department of Engineering Science, University of Oxford, Parks Road, OX1 3PJ Oxford, United Kingdom
| | - Zhanfeng Cui
- Department of Engineering Science, University of Oxford, Parks Road, OX1 3PJ Oxford, United Kingdom
| | - Frank Schmidt
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Felix-Hausdorff-Str. 8, 17475 Greifswald, Germany
- Proteomics Core, Weill Cornel Medicine-Qatar, Education City, PO 24144 Doha, Qatar
| | - Wei E. Huang
- Department of Engineering Science, University of Oxford, Parks Road, OX1 3PJ Oxford, United Kingdom
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574
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Benoit M, Drost HG, Catoni M, Gouil Q, Lopez-Gomollon S, Baulcombe D, Paszkowski J. Environmental and epigenetic regulation of Rider retrotransposons in tomato. PLoS Genet 2019; 15:e1008370. [PMID: 31525177 PMCID: PMC6762207 DOI: 10.1371/journal.pgen.1008370] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 09/26/2019] [Accepted: 08/14/2019] [Indexed: 11/18/2022] Open
Abstract
Transposable elements in crop plants are the powerful drivers of phenotypic variation that has been selected during domestication and breeding programs. In tomato, transpositions of the LTR (long terminal repeat) retrotransposon family Rider have contributed to various phenotypes of agronomical interest, such as fruit shape and colour. However, the mechanisms regulating Rider activity are largely unknown. We have developed a bioinformatics pipeline for the functional annotation of retrotransposons containing LTRs and defined all full-length Rider elements in the tomato genome. Subsequently, we showed that accumulation of Rider transcripts and transposition intermediates in the form of extrachromosomal DNA is triggered by drought stress and relies on abscisic acid signalling. We provide evidence that residual activity of Rider is controlled by epigenetic mechanisms involving siRNAs and the RNA-dependent DNA methylation pathway. Finally, we demonstrate the broad distribution of Rider-like elements in other plant species, including crops. Our work identifies Rider as an environment-responsive element and a potential source of genetic and epigenetic variation in plants. Transposons are major constituents of plant genomes and represent a powerful source of internal genetic and epigenetic variation. For example, domestication of maize has been facilitated by a dramatic change in plant architecture, the consequence of a transposition event. Insertion of transposons near genes often confers quantitative phenotypic variation linked to changes in transcriptional patterns, as documented for blood oranges and grapes. In tomato, the most widely grown fruit crop and model for fleshy fruit biology, occurrences of several beneficial traits related to fruit shape and plant architecture are due to the activity of the transposon family Rider. While Rider represents a unique endogenous source of genetic and epigenetic variation, mechanisms regulating Rider activity remain unexplored. By achieving experimentally-controlled activation of the Rider family, we shed light on the regulation of these transposons by drought stress, signalling by phytohormones, as well as epigenetic pathways. Furthermore, we reveal the presence of Rider-like elements in other economically important crops such as rapeseed, beetroot and quinoa. This suggests that drought-inducible Rider activation could be further harnessed to generate genetic and epigenetic variation for crop breeding, and highlights the potential of transposon-directed mutagenesis for crop improvement.
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Affiliation(s)
- Matthias Benoit
- The Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
| | - Hajk-Georg Drost
- The Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Marco Catoni
- The Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Quentin Gouil
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Sara Lopez-Gomollon
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - David Baulcombe
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Jerzy Paszkowski
- The Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom
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575
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An Evolutionary Perspective on the Impact of Genomic Copy Number Variation on Human Health. J Mol Evol 2019; 88:104-119. [PMID: 31522275 DOI: 10.1007/s00239-019-09911-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 08/27/2019] [Indexed: 02/06/2023]
Abstract
Copy number variants (CNVs), deletions and duplications of segments of DNA, account for at least five times more variable base pairs in humans than single-nucleotide variants. Several common CNVs were shown to change coding and regulatory sequences and thus dramatically affect adaptive phenotypes involving immunity, perception, metabolism, skin structure, among others. Some of these CNVs were also associated with susceptibility to cancer, infection, and metabolic disorders. These observations raise the possibility that CNVs are a primary contributor to human phenotypic variation and consequently evolve under selective pressures. Indeed, locus-specific haplotype-level analyses revealed signatures of natural selection on several CNVs. However, more traditional tests of selection which are often applied to single-nucleotide variation often have diminished statistical power when applied to CNVs because they often do not show strong linkage disequilibrium with nearby variants. Recombination-based formation mechanisms of CNVs lead to frequent recurrence and gene conversion events, breaking the linkage disequilibrium involving CNVs. Similar methodological challenges also prevent routine genome-wide association studies to adequately investigate the impact of CNVs on heritable human disease. Thus, we argue that the full relevance of CNVs to human health and evolution is yet to be elucidated. We further argue that a holistic investigation of formation mechanisms within an evolutionary framework would provide a powerful framework to understand the functional and biomedical impact of CNVs. In this paper, we review several cases where studies reveal diverse evolutionary histories and unexpected functional consequences of CNVs. We hope that this review will encourage further work on CNVs by both evolutionary and medical geneticists.
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576
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577
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Ali A, Khan M, Sharif R, Mujtaba M, Gao SJ. Sugarcane Omics: An Update on the Current Status of Research and Crop Improvement. PLANTS (BASEL, SWITZERLAND) 2019; 8:E344. [PMID: 31547331 PMCID: PMC6784093 DOI: 10.3390/plants8090344] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/08/2019] [Accepted: 08/20/2019] [Indexed: 12/20/2022]
Abstract
Sugarcane is an important crop from Poaceae family, contributing about 80% of the total world's sucrose with an annual value of around US$150 billion. In addition, sugarcane is utilized as a raw material for the production of bioethanol, which is an alternate source of renewable energy. Moving towards sugarcane omics, a remarkable success has been achieved in gene transfer from a wide variety of plant and non-plant sources to sugarcane, with the accessibility of efficient transformation systems, selectable marker genes, and genetic engineering gears. Genetic engineering techniques make possible to clone and characterize useful genes and also to improve commercially important traits in elite sugarcane clones that subsequently lead to the development of an ideal cultivar. Sugarcane is a complex polyploidy crop, and hence no single technique has been found to be the best for the confirmation of polygenic and phenotypic characteristics. To better understand the application of basic omics in sugarcane regarding agronomic characters and industrial quality traits as well as responses to diverse biotic and abiotic stresses, it is important to explore the physiology, genome structure, functional integrity, and collinearity of sugarcane with other more or less similar crops/plants. Genetic improvements in this crop are hampered by its complex genome, low fertility ratio, longer production cycle, and susceptibility to several biotic and abiotic stresses. Biotechnology interventions are expected to pave the way for addressing these obstacles and improving sugarcane crop. Thus, this review article highlights up to date information with respect to how advanced data of omics (genomics, transcriptomic, proteomics and metabolomics) can be employed to improve sugarcane crops.
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Affiliation(s)
- Ahmad Ali
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Mehran Khan
- Department of Plant Protection, Faculty of Agricultural Sciences, Ghazi University, Dera Ghazi Khan, Punjab 32200, Pakistan
| | - Rahat Sharif
- College of Horticulture, Northwest A&F University, Yangling 712100, China
| | - Muhammad Mujtaba
- Institute of Biotechnology, Ankara University, Ankara 06110, Turkey
| | - San-Ji Gao
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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578
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Yandım C, Karakülah G. Dysregulated expression of repetitive DNA in ER+/HER2- breast cancer. Cancer Genet 2019; 239:36-45. [PMID: 31536958 DOI: 10.1016/j.cancergen.2019.09.002] [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] [Received: 04/12/2019] [Revised: 07/03/2019] [Accepted: 09/05/2019] [Indexed: 12/12/2022]
Abstract
Limited studies on breast cancer indicated pathogenic changes in the expressions of some repeat elements. A global analysis was much needed within this context to distinguish the most significant repeats from more than a thousand repeat motifs. Utilising a previously presented RNA-seq dataset, we studied expression changes of all repeats in ER+/HER2- human breast tumour samples obtained from 22 patients in comparison to matched normal tissues. Fifty six (56) repeat subtypes including satellites and transposons were found to be differentially expressed and most of them were novel for breast cancer. HERVKC4-int and HERV1_LTRc, whose expressions correlated well with that of the estrogen receptor gene ESR1, were upregulated at the highest level. REP522 and D20S16 satellites were also significantly upregulated along with insignificant increases in the expressions of other satellites including HSATI and BSR/beta. Interestingly, expressions of REP522 and D20S16 correlated with many key breast cancer pathway (e.g. BRCA1, BRCA2, AKT1, MTOR, KRAS) and survival genes; possibly highlighting their importance in the carcinogenesis of breast. Additional differentially expressed elements such as L1P and various MER transposons also exhibited a similar pattern. Finally, our repeat enrichment analysis on the promoters of differentially expressed genes revealed further links between additional repeats and nearby genes.
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Affiliation(s)
- Cihangir Yandım
- İzmir University of Economics, Faculty of Engineering, Department of Genetics and Bioengineering, 35330, Balçova, İzmir, Turkey; İzmir Biomedicine and Genome Center (IBG), Dokuz Eylül University Health Campus, 35340, İnciraltı, İzmir, Turkey
| | - Gökhan Karakülah
- İzmir Biomedicine and Genome Center (IBG), Dokuz Eylül University Health Campus, 35340, İnciraltı, İzmir, Turkey; İzmir International Biomedicine and Genome Institute (iBG-İzmir), Dokuz Eylül University, 35340, İnciraltı, İzmir, Turkey.
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579
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Hormozdiari F, van de Geijn B, Nasser J, Weissbrod O, Gazal S, Ju CJT, Connor LO, Hujoel MLA, Engreitz J, Hormozdiari F, Price AL. Functional disease architectures reveal unique biological role of transposable elements. Nat Commun 2019; 10:4054. [PMID: 31492842 PMCID: PMC6731302 DOI: 10.1038/s41467-019-11957-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 08/08/2019] [Indexed: 12/19/2022] Open
Abstract
Transposable elements (TE) comprise roughly half of the human genome. Though initially derided as junk DNA, they have been widely hypothesized to contribute to the evolution of gene regulation. However, the contribution of TE to the genetic architecture of diseases remains unknown. Here, we analyze data from 41 independent diseases and complex traits to draw three conclusions. First, TE are uniquely informative for disease heritability. Despite overall depletion for heritability (54% of SNPs, 39 ± 2% of heritability), TE explain substantially more heritability than expected based on their depletion for known functional annotations. This implies that TE acquire function in ways that differ from known functional annotations. Second, older TE contribute more to disease heritability, consistent with acquiring biological function. Third, Short Interspersed Nuclear Elements (SINE) are far more enriched for blood traits than for other traits. Our results can help elucidate the biological roles that TE play in the genetic architecture of diseases.
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Affiliation(s)
- Farhad Hormozdiari
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA. .,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Bryce van de Geijn
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Joseph Nasser
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Omer Weissbrod
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Steven Gazal
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Chelsea J-T Ju
- Department of Computer Science, University of California, Los Angeles, CA, 90095, USA
| | - Luke O' Connor
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.,Program in Bioinformatics and Integrative Genomics, Harvard Graduate School of Arts and Sciences, Boston, MA, USA
| | - Margaux L A Hujoel
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Jesse Engreitz
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Fereydoun Hormozdiari
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA, 95616, USA.,MIND Institute and UC-Davis Genome Center, Davis, CA, 95616, USA
| | - Alkes L Price
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA. .,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA. .,Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.
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580
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Chung N, Jonaid GM, Quinton S, Ross A, Sexton CE, Alberto A, Clymer C, Churchill D, Navarro Leija O, Han MV. Transcriptome analyses of tumor-adjacent somatic tissues reveal genes co-expressed with transposable elements. Mob DNA 2019; 10:39. [PMID: 31497073 PMCID: PMC6720085 DOI: 10.1186/s13100-019-0180-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 08/14/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Despite the long-held assumption that transposons are normally only expressed in the germ-line, recent evidence shows that transcripts of transposable element (TE) sequences are frequently found in the somatic cells. However, the extent of variation in TE transcript levels across different tissues and different individuals are unknown, and the co-expression between TEs and host gene mRNAs have not been examined. RESULTS Here we report the variation in TE derived transcript levels across tissues and between individuals observed in the non-tumorous tissues collected for The Cancer Genome Atlas. We found core TE co-expression modules consisting mainly of transposons, showing correlated expression across broad classes of TEs. Despite this co-expression within tissues, there are individual TE loci that exhibit tissue-specific expression patterns, when compared across tissues. The core TE modules were negatively correlated with other gene modules that consisted of immune response genes in interferon signaling. KRAB Zinc Finger Proteins (KZFPs) were over-represented gene members of the TE modules, showing positive correlation across multiple tissues. But we did not find overlap between TE-KZFP pairs that are co-expressed and TE-KZFP pairs that are bound in published ChIP-seq studies. CONCLUSIONS We find unexpected variation in TE derived transcripts, within and across non-tumorous tissues. We describe a broad view of the RNA state for non-tumorous tissues exhibiting higher level of TE transcripts. Tissues with higher level of TE transcripts have a broad range of TEs co-expressed, with high expression of a large number of KZFPs, and lower RNA levels of immune genes.
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Affiliation(s)
- Nicky Chung
- School of Life Sciences, University of Nevada, Las Vegas, NV 89154 USA
| | - G. M. Jonaid
- School of Life Sciences, University of Nevada, Las Vegas, NV 89154 USA
| | - Sophia Quinton
- School of Life Sciences, University of Nevada, Las Vegas, NV 89154 USA
| | - Austin Ross
- School of Life Sciences, University of Nevada, Las Vegas, NV 89154 USA
| | - Corinne E. Sexton
- School of Life Sciences, University of Nevada, Las Vegas, NV 89154 USA
| | - Adrian Alberto
- Department of Computer Science, University of Nevada, Las Vegas, NV 89154 USA
| | - Cody Clymer
- Department of Computer Science, University of Nevada, Las Vegas, NV 89154 USA
| | - Daphnie Churchill
- Department of Computer Science, University of Nevada, Las Vegas, NV 89154 USA
| | - Omar Navarro Leija
- Department of Computer Science, University of Nevada, Las Vegas, NV 89154 USA
| | - Mira V. Han
- School of Life Sciences, University of Nevada, Las Vegas, NV 89154 USA
- Nevada Institute of Personalized Medicine, Las Vegas, NV 89154 USA
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581
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Murano K, Iwasaki YW, Ishizu H, Mashiko A, Shibuya A, Kondo S, Adachi S, Suzuki S, Saito K, Natsume T, Siomi MC, Siomi H. Nuclear RNA export factor variant initiates piRNA-guided co-transcriptional silencing. EMBO J 2019; 38:e102870. [PMID: 31368590 PMCID: PMC6717896 DOI: 10.15252/embj.2019102870] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 07/10/2019] [Accepted: 07/11/2019] [Indexed: 12/20/2022] Open
Abstract
The PIWI-interacting RNA (piRNA) pathway preserves genomic integrity by repressing transposable elements (TEs) in animal germ cells. Among PIWI-clade proteins in Drosophila, Piwi transcriptionally silences its targets through interactions with cofactors, including Panoramix (Panx) and forms heterochromatin characterized by H3K9me3 and H1. Here, we identified Nxf2, a nuclear RNA export factor (NXF) variant, as a protein that forms complexes with Piwi, Panx, and p15. Panx-Nxf2-P15 complex formation is necessary in the silencing by stabilizing protein levels of Nxf2 and Panx. Notably, ectopic targeting of Nxf2 initiates co-transcriptional repression of the target reporter in a manner independent of H3K9me3 marks or H1. However, continuous silencing requires HP1a and H1. In addition, Nxf2 directly interacts with target TE transcripts in a Piwi-dependent manner. These findings suggest a model in which the Panx-Nxf2-P15 complex enforces the association of Piwi with target transcripts to trigger co-transcriptional repression, prior to heterochromatin formation in the nuclear piRNA pathway. Our results provide an unexpected connection between an NXF variant and small RNA-mediated co-transcriptional silencing.
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Affiliation(s)
- Kensaku Murano
- Department of Molecular BiologyKeio University School of MedicineTokyoJapan
| | - Yuka W Iwasaki
- Department of Molecular BiologyKeio University School of MedicineTokyoJapan
| | - Hirotsugu Ishizu
- Department of Molecular BiologyKeio University School of MedicineTokyoJapan
| | - Akane Mashiko
- Department of Molecular BiologyKeio University School of MedicineTokyoJapan
- Graduate School of EngineeringYokohama National UniversityYokohamaJapan
| | - Aoi Shibuya
- Department of Molecular BiologyKeio University School of MedicineTokyoJapan
| | - Shu Kondo
- Invertebrate Genetics LaboratoryNational Institute of GeneticsMishimaShizuokaJapan
| | - Shungo Adachi
- Molecular Profiling Research Center for Drug DiscoveryNational Institute of Advanced Industrial Science and TechnologyTokyoJapan
| | - Saori Suzuki
- Department of Biological SciencesGraduate School of ScienceThe University of TokyoTokyoJapan
| | - Kuniaki Saito
- Invertebrate Genetics LaboratoryNational Institute of GeneticsMishimaShizuokaJapan
| | - Tohru Natsume
- Molecular Profiling Research Center for Drug DiscoveryNational Institute of Advanced Industrial Science and TechnologyTokyoJapan
| | - Mikiko C Siomi
- Department of Biological SciencesGraduate School of ScienceThe University of TokyoTokyoJapan
| | - Haruhiko Siomi
- Department of Molecular BiologyKeio University School of MedicineTokyoJapan
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582
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Abstract
Transposable elements (TEs) are mobile DNA sequences that colonize genomes and threaten genome integrity. As a result, several mechanisms appear to have emerged during eukaryotic evolution to suppress TE activity. However, TEs are ubiquitous and account for a prominent fraction of most eukaryotic genomes. We argue that the evolutionary success of TEs cannot be explained solely by evasion from host control mechanisms. Rather, some TEs have evolved commensal and even mutualistic strategies that mitigate the cost of their propagation. These coevolutionary processes promote the emergence of complex cellular activities, which in turn pave the way for cooption of TE sequences for organismal function.
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Affiliation(s)
- Rachel L Cosby
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
| | - Ni-Chen Chang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
| | - Cédric Feschotte
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
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583
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Catoni M, Jonesman T, Cerruti E, Paszkowski J. Mobilization of Pack-CACTA transposons in Arabidopsis suggests the mechanism of gene shuffling. Nucleic Acids Res 2019; 47:1311-1320. [PMID: 30476196 PMCID: PMC6379663 DOI: 10.1093/nar/gky1196] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/08/2018] [Accepted: 11/16/2018] [Indexed: 11/21/2022] Open
Abstract
Pack-TYPE transposons are a unique class of potentially mobile non-autonomous elements that can capture, merge and relocate fragments of chromosomal DNA. It has been postulated that their activity accelerates the evolution of host genes. However, this important presumption is based only on the sequences of currently inactive Pack-TYPE transposons and the acquisition of chromosomal DNA has not been recorded in real time. Analysing the DNA copy number variation in hypomethylated Arabidopsis lines, we have now for the first time witnessed the mobilization of novel Pack-TYPE elements related to the CACTA transposon family, over several plant generations. Remarkably, these elements can insert into genes as closely spaced direct repeats and they frequently undergo incomplete excisions, resulting in the deletion of one of the end sequences. These properties suggest a mechanism of efficient acquisition of genic DNA residing between neighbouring Pack-TYPE transposons and its subsequent mobilization. Our work documents crucial steps in the formation of in vivo novel Pack-TYPE transposons, and thus the possible mechanism of gene shuffling mediated by this type of mobile element.
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Affiliation(s)
- Marco Catoni
- The Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK.,School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Thomas Jonesman
- The Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK
| | - Elisa Cerruti
- The Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK
| | - Jerzy Paszkowski
- The Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, UK
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584
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Saleh A, Macia A, Muotri AR. Transposable Elements, Inflammation, and Neurological Disease. Front Neurol 2019; 10:894. [PMID: 31481926 PMCID: PMC6710400 DOI: 10.3389/fneur.2019.00894] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 08/02/2019] [Indexed: 12/13/2022] Open
Abstract
Transposable Elements (TE) are mobile DNA elements that can replicate and insert themselves into different locations within the host genome. Their propensity to self-propagate has a myriad of consequences and yet their biological significance is not well-understood. Indeed, retrotransposons have evaded evolutionary attempts at repression and may contribute to somatic mosaicism. Retrotransposons are emerging as potent regulatory elements within the human genome. In the diseased state, there is mounting evidence that endogenous retroelements play a role in etiopathogenesis of inflammatory diseases, with a disposition for both autoimmune and neurological disorders. We postulate that active mobile genetic elements contribute more to human disease pathogenesis than previously thought.
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Affiliation(s)
- Aurian Saleh
- Department of Pediatrics, Rady Children's Hospital San Diego, University of California, San Diego, San Diego, CA, United States
| | - Angela Macia
- Department of Pediatrics, Rady Children's Hospital San Diego, University of California, San Diego, San Diego, CA, United States
| | - Alysson R Muotri
- Department of Pediatrics, Rady Children's Hospital San Diego, University of California, San Diego, San Diego, CA, United States
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585
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586
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Mustafin RN, Khusnutdinova EK. The Role of Reverse Transcriptase in the Origin of Life. BIOCHEMISTRY (MOSCOW) 2019; 84:870-883. [DOI: 10.1134/s0006297919080030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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587
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Sun Y, Miao N, Sun T. Detect accessible chromatin using ATAC-sequencing, from principle to applications. Hereditas 2019; 156:29. [PMID: 31427911 PMCID: PMC6696680 DOI: 10.1186/s41065-019-0105-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 08/12/2019] [Indexed: 02/07/2023] Open
Abstract
Background Chromatin accessibility is crucial for gene expression regulation in specific cells and in multiple biological processes. Assay for Transposase Accessible Chromatin with high-throughput sequencing (ATAC-seq) is an effective way to reveal chromatin accessibility at a genome-wide level. Through ATAC-seq, produced reads from a small number of cells reflect accessible regions that correspond to nucleosome positioning and transcription factor binding sites, due to probing hyperactive Tn5 transposase to DNA sequence. Conclusion In this review, we summarize both principle and features of ATAC-seq, highlight its applications in basic and clinical research. ATAC-seq has generated comprehensive chromatin accessible maps, and is becoming a powerful tool to understand dynamic gene expression regulation in stem cells, early embryos and tumors.
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Affiliation(s)
- Yuanyuan Sun
- Center for Precision Medicine, School of Medicine and School of Biomedical Sciences, Huaqiao University, 668 Jimei Road, Xiamen, 361021 Fujian China
| | - Nan Miao
- Center for Precision Medicine, School of Medicine and School of Biomedical Sciences, Huaqiao University, 668 Jimei Road, Xiamen, 361021 Fujian China
| | - Tao Sun
- Center for Precision Medicine, School of Medicine and School of Biomedical Sciences, Huaqiao University, 668 Jimei Road, Xiamen, 361021 Fujian China
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588
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Ray DA, Grimshaw JR, Halsey MK, Korstian JM, Osmanski AB, Sullivan KAM, Wolf KA, Reddy H, Foley N, Stevens RD, Knisbacher BA, Levy O, Counterman B, Edelman NB, Mallet J. Simultaneous TE Analysis of 19 Heliconiine Butterflies Yields Novel Insights into Rapid TE-Based Genome Diversification and Multiple SINE Births and Deaths. Genome Biol Evol 2019; 11:2162-2177. [PMID: 31214686 PMCID: PMC6685494 DOI: 10.1093/gbe/evz125] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2019] [Indexed: 12/21/2022] Open
Abstract
Transposable elements (TEs) play major roles in the evolution of genome structure and function. However, because of their repetitive nature, they are difficult to annotate and discovering the specific roles they may play in a lineage can be a daunting task. Heliconiine butterflies are models for the study of multiple evolutionary processes including phenotype evolution and hybridization. We attempted to determine how TEs may play a role in the diversification of genomes within this clade by performing a detailed examination of TE content and accumulation in 19 species whose genomes were recently sequenced. We found that TE content has diverged substantially and rapidly in the time since several subclades shared a common ancestor with each lineage harboring a unique TE repertoire. Several novel SINE lineages have been established that are restricted to a subset of species. Furthermore, the previously described SINE, Metulj, appears to have gone extinct in two subclades while expanding to significant numbers in others. This diversity in TE content and activity has the potential to impact how heliconiine butterflies continue to evolve and diverge.
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Affiliation(s)
- David A Ray
- Department of Biological Science, Texas Tech University
| | | | | | | | | | | | | | - Harsith Reddy
- Department of Biological Science, Texas Tech University
| | - Nicole Foley
- Department of Biological Science, Texas Tech University
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX
| | | | - Binyamin A Knisbacher
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
- Broad Institute of MIT and Harvard, Cambridge, MA
| | - Orr Levy
- Department of Physics, Bar-Ilan University, Ramat Gan, Israel
| | | | | | - James Mallet
- Department of Organismic and Evolutionary Biology, Harvard University
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589
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Transposition favors the generation of large effect mutations that may facilitate rapid adaption. Nat Commun 2019; 10:3421. [PMID: 31366887 PMCID: PMC6668482 DOI: 10.1038/s41467-019-11385-5] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 07/12/2019] [Indexed: 12/13/2022] Open
Abstract
Transposable elements (TEs) are mobile parasitic sequences that have been repeatedly coopted during evolution to generate new functions and rewire gene regulatory networks. Yet, the contribution of active TEs to the creation of heritable mutations remains unknown. Using TE accumulation lines in Arabidopsis thaliana we show that once initiated, transposition produces an exponential spread of TE copies, which rapidly leads to high mutation rates. Most insertions occur near or within genes and targets differ between TE families. Furthermore, we uncover an essential role of the histone variant H2A.Z in the preferential integration of Ty1/copia retrotransposons within environmentally responsive genes and away from essential genes. We also show that epigenetic silencing of new Ty1/copia copies can affect their impact on major fitness-related traits, including flowering time. Our findings demonstrate that TEs are potent episodic (epi)mutagens that, thanks to marked chromatin tropisms, limit the mutation load and increase the potential for rapid adaptation.
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590
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Hickman AB, Voth AR, Ewis H, Li X, Craig NL, Dyda F. Structural insights into the mechanism of double strand break formation by Hermes, a hAT family eukaryotic DNA transposase. Nucleic Acids Res 2019; 46:10286-10301. [PMID: 30239795 PMCID: PMC6212770 DOI: 10.1093/nar/gky838] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 09/07/2018] [Indexed: 12/12/2022] Open
Abstract
Some DNA transposons relocate from one genomic location to another using a mechanism that involves generating double-strand breaks at their transposon ends by forming hairpins on flanking DNA. The same double-strand break mode is employed by the V(D)J recombinase at signal-end/coding-end junctions during the generation of antibody diversity. How flanking hairpins are formed during DNA transposition has remained elusive. Here, we describe several co-crystal structures of the Hermes transposase bound to DNA that mimics the reaction step immediately prior to hairpin formation. Our results reveal a large DNA conformational change between the initial cleavage step and subsequent hairpin formation that changes which strand is acted upon by a single active site. We observed that two factors affect the conformational change: the complement of divalent metal ions bound by the catalytically essential DDE residues, and the identity of the –2 flanking base pair. Our data also provides a mechanistic link between the efficiency of hairpin formation (an A:T basepair is favored at the –2 position) and Hermes' strong target site preference. Furthermore, we have established that the histidine residue within a conserved C/DxxH motif present in many transposase families interacts directly with the scissile phosphate, suggesting a crucial role in catalysis.
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Affiliation(s)
- Alison B Hickman
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Andrea Regier Voth
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hosam Ewis
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Xianghong Li
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nancy L Craig
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Fred Dyda
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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591
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An endogenous retroviral element exerts an antiviral innate immune function via the derived lncRNA lnc-ALVE1-AS1. Antiviral Res 2019; 170:104571. [PMID: 31374219 DOI: 10.1016/j.antiviral.2019.104571] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/27/2019] [Accepted: 07/29/2019] [Indexed: 11/24/2022]
Abstract
Endogenous retroviruses (ERVs) constitute an important component of animal and human genomes and are usually silenced by epigenetic mechanisms in adult cells. Although ERVs were recently reported to be linked to early development, tumorigenesis and autoimmune disease, their impacts on antiviral innate immunity and the underlying mechanisms have not been elucidated. Here, we provide the first direct evidence of an endogenous retroviral element affecting antiviral innate immunity via its derived antisense long non-coding RNA (lncRNA). We found that an antisense lncRNA, which is called lnc-ALVE1-AS1 and is transcribed from the endogenous avian leukosis virus in chromosome 1 (ALVE1), distinctly inhibited the entry and replication of exogenous retroviruses in chicken embryonic fibroblasts (CEFs). This behaviour is at least in part attributed to the induction of an antiviral innate immune pathway by ALVE1 activation, suggesting that an activated endogenous retroviral element may induce antiviral defence responses via its derived antisense lncRNA. We also found that lnc-ALVE1-AS1 mediated these effects by activating the TLR3 signalling in the cytoplasm. Our results provide novel insights into the antiviral innate immune function of ERVs, suggesting that ERVs may play an important role in antiviral defences and provide new strategies for the development of new vaccines.
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592
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Maizels N, Davis L. Initiation of homologous recombination at DNA nicks. Nucleic Acids Res 2019; 46:6962-6973. [PMID: 29986051 PMCID: PMC6101574 DOI: 10.1093/nar/gky588] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/04/2018] [Indexed: 12/14/2022] Open
Abstract
Discontinuities in only a single strand of the DNA duplex occur frequently, as a result of DNA damage or as intermediates in essential nuclear processes and DNA repair. Nicks are the simplest of these lesions: they carry clean ends bearing 3′-hydroxyl groups that can undergo ligation or prime new DNA synthesis. In contrast, single-strand breaks also interrupt only one DNA strand, but they carry damaged ends that require clean-up before subsequent steps in repair. Despite their apparent simplicity, nicks can have significant consequences for genome stability. The availability of enzymes that can introduce a nick almost anywhere in a large genome now makes it possible to systematically analyze repair of nicks. Recent experiments demonstrate that nicks can initiate recombination via pathways distinct from those active at double-strand breaks (DSBs). Recombination at targeted DNA nicks can be very efficient, and because nicks are intrinsically less mutagenic than DSBs, nick-initiated gene correction is useful for genome engineering and gene therapy. This review revisits some physiological examples of recombination at nicks, and outlines experiments that have demonstrated that nicks initiate homology-directed repair by distinctive pathways, emphasizing research that has contributed to our current mechanistic understanding of recombination at nicks in mammalian cells.
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Affiliation(s)
- Nancy Maizels
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195, USA.,Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Luther Davis
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195, USA
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593
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Li F, An Z, Zhang Z. The Dynamic 3D Genome in Gametogenesis and Early Embryonic Development. Cells 2019; 8:E788. [PMID: 31362461 PMCID: PMC6721571 DOI: 10.3390/cells8080788] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/11/2019] [Accepted: 07/20/2019] [Indexed: 12/15/2022] Open
Abstract
During gametogenesis and early embryonic development, the chromatin architecture changes dramatically, and both the transcriptomic and epigenomic landscape are comprehensively reprogrammed. Understanding these processes is the holy grail in developmental biology and a key step towards evolution. The 3D conformation of chromatin plays a central role in the organization and function of nuclei. Recently, the dynamics of chromatin structures have been profiled in many model and non-model systems, from insects to mammals, resulting in an interesting comparison. In this review, we first introduce the research methods of 3D chromatin structure with low-input material suitable for embryonic study. Then, the dynamics of 3D chromatin architectures during gametogenesis and early embryonic development is summarized and compared between species. Finally, we discuss the possible mechanisms for triggering the formation of genome 3D conformation in early development.
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Affiliation(s)
- Feifei Li
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Ziyang An
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
- School of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhihua Zhang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.
- School of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China.
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594
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Heterogeneous transposable elements as silencers, enhancers and targets of meiotic recombination. Chromosoma 2019; 128:279-296. [PMID: 31332531 DOI: 10.1007/s00412-019-00718-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 06/25/2019] [Accepted: 07/01/2019] [Indexed: 02/01/2023]
Abstract
During meiosis, DNA double-strand breaks are initiated by the topoisomerase-like enzyme SPO11 and are repaired by inter-sister chromatid and inter-homologue DNA repair pathways. Genome-wide maps of initiating DNA double-strand breaks and inter-homologue repair events are now available for a number of mammalian, fungal and plant species. In mammals, PRDM9 specifies the location of meiotic recombination initiation via recognition of specific DNA sequence motifs by its C2H2 zinc finger array. In fungi and plants, meiotic recombination appears to be initiated less discriminately in accessible chromatin, including at gene promoters. Generally, meiotic crossover is suppressed in highly repetitive genomic regions that are made up of transposable elements (TEs), to prevent deleterious non-allelic homologous recombination events. However, recent and older studies have revealed intriguing relationships between meiotic recombination initiation and repair, and transposable elements. For instance, gene conversion events have been detected in maize centromeric retroelements, mouse MULE-MuDR DNA transposons undergo substantial meiotic recombination initiation, Arabidopsis Helitron TEs are among the hottest of recombination initiation hotspots, and human TE sequences can modify the crossover rate at adjacent PRDM9 motifs in cis. Here, we summarize the relationship between meiotic recombination and TEs, discuss recent insights from highly divergent eukaryotes and highlight outstanding questions in the field.
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595
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Abstract
Maintenance of genome stability requires control over the expression of transposable elements (TEs), whose activity can have substantial deleterious effects on the host. Chemical modification of DNA is a commonly used strategy to achieve this, and it has long been argued that the emergence of 5-methylcytosine (5mC) in many species was driven by the requirement to silence TEs. Potential roles in TE regulation have also been suggested for other DNA modifications, such as N6-methyladenine and oxidation derivatives of 5mC, although the underlying mechanistic relationships are poorly understood. Here, we discuss current evidence implicating DNA modifications and DNA-modifying enzymes in TE regulation across different species.
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Affiliation(s)
- Özgen Deniz
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London, UK
| | - Jennifer M Frost
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London, UK
| | - Miguel R Branco
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London, UK.
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596
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Transposable Elements Adaptive Role in Genome Plasticity, Pathogenicity and Evolution in Fungal Phytopathogens. Int J Mol Sci 2019; 20:ijms20143597. [PMID: 31340492 PMCID: PMC6679389 DOI: 10.3390/ijms20143597] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 06/18/2019] [Accepted: 06/25/2019] [Indexed: 01/08/2023] Open
Abstract
Transposable elements (TEs) are agents of genetic variability in phytopathogens as they are a source of adaptive evolution through genome diversification. Although many studies have uncovered information on TEs, the exact mechanism behind TE-induced changes within the genome remains poorly understood. Furthermore, convergent trends towards bigger genomes, emergence of novel genes and gain or loss of genes implicate a TE-regulated genome plasticity of fungal phytopathogens. TEs are able to alter gene expression by revamping the cis-regulatory elements or recruiting epigenetic control. Recent findings show that TEs recruit epigenetic control on the expression of effector genes as part of the coordinated infection strategy. In addition to genome plasticity and diversity, fungal pathogenicity is an area of economic concern. A survey of TE distribution suggests that their proximity to pathogenicity genes TEs may act as sites for emergence of novel pathogenicity factors via nucleotide changes and expansion or reduction of the gene family. Through a systematic survey of literature, we were able to conclude that the role of TEs in fungi is wide: ranging from genome plasticity, pathogenicity to adaptive behavior in evolution. This review also identifies the gaps in knowledge that requires further elucidation for a better understanding of TEs' contribution to genome architecture and versatility.
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597
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Rogers RL, Zhou L, Chu C, Márquez R, Corl A, Linderoth T, Freeborn L, MacManes MD, Xiong Z, Zheng J, Guo C, Xun X, Kronforst MR, Summers K, Wu Y, Yang H, Richards-Zawacki CL, Zhang G, Nielsen R. Genomic Takeover by Transposable Elements in the Strawberry Poison Frog. Mol Biol Evol 2019; 35:2913-2927. [PMID: 30517748 PMCID: PMC6278860 DOI: 10.1093/molbev/msy185] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We sequenced the genome of the strawberry poison frog, Oophaga pumilio, at a depth of 127.5× using variable insert size libraries. The total genome size is estimated to be 6.76 Gb, of which 4.76 Gb are from high copy number repetitive elements with low differentiation across copies. These repeats encompass DNA transposons, RNA transposons, and LTR retrotransposons, including at least 0.4 and 1.0 Gb of Mariner/Tc1 and Gypsy elements, respectively. Expression data indicate high levels of gypsy and Mariner/Tc1 expression in ova of O. pumilio compared with Xenopus laevis. We further observe phylogenetic evidence for horizontal transfer (HT) of Mariner elements, possibly between fish and frogs. The elements affected by HT are present in high copy number and are highly expressed, suggesting ongoing proliferation after HT. Our results suggest that the large amphibian genome sizes, at least partially, can be explained by a process of repeated invasion of new transposable elements that are not yet suppressed in the germline. We also find changes in the spliceosome that we hypothesize are related to permissiveness of O. pumilio to increases in intron length due to transposon proliferation. Finally, we identify the complement of ion channels in the first genomic sequenced poison frog and discuss its relation to the evolution of autoresistance to toxins sequestered in the skin.
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Affiliation(s)
- Rebekah L Rogers
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte, NC
| | - Long Zhou
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,China National Genebank, BGI-Shenzhen, Shenzhen, Guangdong, China
| | - Chong Chu
- Harvard Medical School, Harvard University, Cambridge, MA
| | - Roberto Márquez
- Department of Ecology and Evolution, University of Chicago, Chicago, IL
| | - Ammon Corl
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA
| | - Tyler Linderoth
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA
| | - Layla Freeborn
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Matthew D MacManes
- Department of Molecular Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH.,Hubbard Center for Genomic Studies, University of New Hampshire, Durham, NH
| | - Zijun Xiong
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Jiao Zheng
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Chunxue Guo
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Xu Xun
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | | | - Kyle Summers
- Department of Biology, Eastern Carolina University, Greenville, NC
| | - Yufeng Wu
- Department of Computer Science, University of Connecticut, Storrs, CT
| | - Huanming Yang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,James D. Watson Institute of Genome Sciences, Hangzhou, China
| | | | - Guojie Zhang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,China National Genebank, BGI-Shenzhen, Shenzhen, Guangdong, China.,Department of Biology, Centre for Social Evolution, Universitetsparken 15, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Nielsen
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA
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598
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Jönsson ME, Ludvik Brattås P, Gustafsson C, Petri R, Yudovich D, Pircs K, Verschuere S, Madsen S, Hansson J, Larsson J, Månsson R, Meissner A, Jakobsson J. Activation of neuronal genes via LINE-1 elements upon global DNA demethylation in human neural progenitors. Nat Commun 2019; 10:3182. [PMID: 31320637 PMCID: PMC6639357 DOI: 10.1038/s41467-019-11150-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 06/20/2019] [Indexed: 01/14/2023] Open
Abstract
DNA methylation contributes to the maintenance of genomic integrity in somatic cells, in part through the silencing of transposable elements. In this study, we use CRISPR-Cas9 technology to delete DNMT1, the DNA methyltransferase key for DNA methylation maintenance, in human neural progenitor cells (hNPCs). We observe that inactivation of DNMT1 in hNPCs results in viable, proliferating cells despite a global loss of DNA CpG-methylation. DNA demethylation leads to specific transcriptional activation and chromatin remodeling of evolutionarily young, hominoid-specific LINE-1 elements (L1s), while older L1s and other classes of transposable elements remain silent. The activated L1s act as alternative promoters for many protein-coding genes involved in neuronal functions, revealing a hominoid-specific L1-based transcriptional network controlled by DNA methylation that influences neuronal protein-coding genes. Our results provide mechanistic insight into the role of DNA methylation in silencing transposable elements in somatic human cells, as well as further implicating L1s in human brain development and disease. DNA methylation plays an important role in silencing transposable elements. Here the authors find that loss of DNMT1 and DNA methylation leads to transcriptional activation and chromatin remodelling of evolutionarily young—hominoid-specific —LINE-1 elements which then act as alternative promoters for neuronal genes.
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Affiliation(s)
- Marie E Jönsson
- Wallenberg Neuroscience Center and Lund Stem Cell Center, Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, BMC A11, Lund University, 221 84, Lund, Sweden
| | - Per Ludvik Brattås
- Wallenberg Neuroscience Center and Lund Stem Cell Center, Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, BMC A11, Lund University, 221 84, Lund, Sweden
| | - Charlotte Gustafsson
- Center for Hematology and Regenerative Medicine Huddinge, Karolinska Institute, 141 52, Stockholm, Sweden
| | - Rebecca Petri
- Wallenberg Neuroscience Center and Lund Stem Cell Center, Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, BMC A11, Lund University, 221 84, Lund, Sweden
| | - David Yudovich
- Division of Molecular Medicine and Gene Therapy, Department of Laboratory Medicine and Lund Stem Cell Center, BMC A12, Lund University, 221 84, Lund, Sweden
| | - Karolina Pircs
- Wallenberg Neuroscience Center and Lund Stem Cell Center, Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, BMC A11, Lund University, 221 84, Lund, Sweden
| | - Shana Verschuere
- Wallenberg Neuroscience Center and Lund Stem Cell Center, Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, BMC A11, Lund University, 221 84, Lund, Sweden
| | - Sofia Madsen
- Wallenberg Neuroscience Center and Lund Stem Cell Center, Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, BMC A11, Lund University, 221 84, Lund, Sweden
| | - Jenny Hansson
- Laboratory of Proteomic Hematology, Department of Laboratory Medicine and Lund Stem Cell Center, BMC B12, Lund University, 221 84, Lund, Sweden
| | - Jonas Larsson
- Division of Molecular Medicine and Gene Therapy, Department of Laboratory Medicine and Lund Stem Cell Center, BMC A12, Lund University, 221 84, Lund, Sweden
| | - Robert Månsson
- Center for Hematology and Regenerative Medicine Huddinge, Karolinska Institute, 141 52, Stockholm, Sweden
| | - Alexander Meissner
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, 14195, Berlin, Germany
| | - Johan Jakobsson
- Wallenberg Neuroscience Center and Lund Stem Cell Center, Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, BMC A11, Lund University, 221 84, Lund, Sweden.
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599
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Soares MJ, Varberg KM, Iqbal K. Hemochorial placentation: development, function, and adaptations. Biol Reprod 2019; 99:196-211. [PMID: 29481584 DOI: 10.1093/biolre/ioy049] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 02/21/2018] [Indexed: 11/12/2022] Open
Abstract
Placentation is a reproductive adaptation that permits fetal growth and development within the protected confines of the female reproductive tract. Through this important role, the placenta also determines postnatal health and susceptibility to disease. The hemochorial placenta is a prominent feature in primate and rodent development. This manuscript provides an overview of the basics of hemochorial placental development and function, provides perspectives on major discoveries that have shaped placental research, and thoughts on strategies for future investigation.
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Affiliation(s)
- Michael J Soares
- Institute for Reproduction and Perinatal Research and the Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA.,Department of Pediatrics, University of Kansas Medical Center, Kansas City, Kansas, USA and the Center for Perinatal Research, Children΄s Research Institute, Children΄s Mercy, Kansas City, Missouri, USA
| | - Kaela M Varberg
- Institute for Reproduction and Perinatal Research and the Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Khursheed Iqbal
- Institute for Reproduction and Perinatal Research and the Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas, USA
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600
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A Non-Dicer RNase III and Four Other Novel Factors Required for RNAi-Mediated Transposon Suppression in the Human Pathogenic Yeast Cryptococcus neoformans. G3-GENES GENOMES GENETICS 2019; 9:2235-2244. [PMID: 31092606 PMCID: PMC6643885 DOI: 10.1534/g3.119.400330] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The human pathogenic yeast Cryptococcus neoformans silences transposable elements using endo-siRNAs and an Argonaute, Ago1. Endo-siRNAs production requires the RNA-dependent RNA polymerase, Rdp1, and two partially redundant Dicer enzymes, Dcr1 and Dcr2, but is independent of histone H3 lysine 9 methylation. We describe here an insertional mutagenesis screen for factors required to suppress the mobilization of the C. neoformans HARBINGER family DNA transposon HAR1. Validation experiments uncovered five novel genes (RDE1-5) required for HAR1 suppression and global production of suppressive endo-siRNAs. The RDE genes do not impact transcript levels, suggesting the endo-siRNAs do not act by impacting target transcript synthesis or turnover. RDE3 encodes a non-Dicer RNase III related to S. cerevisiaeRnt1, RDE4 encodes a predicted terminal nucleotidyltransferase, while RDE5 has no strongly predicted encoded domains. Affinity purification-mass spectrometry studies suggest that Rde3 and Rde5 are physically associated. RDE1 encodes a G-patch protein homologous to the S. cerevisiaeSqs1/Pfa1, a nucleolar protein that directly activates the essential helicase Prp43 during rRNA biogenesis. Rde1 copurifies Rde2, another novel protein obtained in the screen, as well as Ago1, a homolog of Prp43, and numerous predicted nucleolar proteins. We also describe the isolation of conditional alleles of PRP43, which are defective in RNAi. This work reveals unanticipated requirements for a non-Dicer RNase III and presumptive nucleolar factors for endo-siRNA biogenesis and transposon mobilization suppression in C. neoformans.
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