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Watanabe R, Nakachi Y, Matsubara H, Ueda J, Ishii T, Ukai W, Hashimoto E, Kasai K, Simizu S, Kato T, Bundo M, Iwamoto K. Identification of epigenetically active L1 promoters in the human brain and their relationship with psychiatric disorders. Neurosci Res 2023; 195:37-51. [PMID: 37141946 DOI: 10.1016/j.neures.2023.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 04/09/2023] [Accepted: 05/01/2023] [Indexed: 05/06/2023]
Abstract
Long interspersed nuclear element-1 (LINE-1, L1) affects the transcriptome landscape in multiple ways. Promoter activity within its 5'UTR plays a critical role in regulating diverse L1 activities. However, the epigenetic status of L1 promoters in adult brain cells and their relationship with psychiatric disorders remain poorly understood. Here, we examined DNA methylation and hydroxymethylation of the full-length L1s in neurons and nonneurons and identified "epigenetically active" L1s. Notably, some of epigenetically active L1s were retrotransposition competent, which even had chimeric transcripts from the antisense promoters at their 5'UTRs. We also identified differentially methylated L1s in the prefrontal cortices of patients with psychiatric disorders. In nonneurons of bipolar disorder patients, one L1 was significantly hypomethylated and showed an inverse correlation with the expression level of the overlapping gene NREP. Finally, we observed that altered DNA methylation levels of L1 in patients with psychiatric disorders were not affected by the surrounding genomic regions but originated from the L1 sequences. These results suggested that altered epigenetic regulation of the L1 5'UTR in the brain was involved in the pathophysiology of psychiatric disorders.
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Affiliation(s)
- Risa Watanabe
- Department of Molecular Brain Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Yutaka Nakachi
- Department of Molecular Brain Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Hikari Matsubara
- Department of Molecular Brain Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Junko Ueda
- Department of Molecular Brain Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Takao Ishii
- Department of Occupational Therapy, Sapporo Medical University School of Health Sciences, Sapporo, Japan
| | - Wataru Ukai
- Department of Neuropsychiatry, Sapporo Medical University, School of Medicine, Sapporo, Japan
| | - Eri Hashimoto
- Department of Neuropsychiatry, Sapporo Medical University, School of Medicine, Sapporo, Japan
| | - Kiyoto Kasai
- Department of Neuropsychiatry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; The International Research Center for Neurointelligence (WPI-IRCN), University of Tokyo Institutes for Advanced Study (UTIAS), The University of Tokyo, Tokyo, Japan; University of Tokyo Institute for Diversity and Adaptation of Human Mind (UTIDAHM), The University of Tokyo, Tokyo, Japan; UTokyo Center for Integrative Science of Human Behaviour (CiSHuB), The University of Tokyo, Tokyo, Japan
| | - Siro Simizu
- Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Yokohama, Japan
| | - Tadafumi Kato
- Department of Psychiatry and Behavioral Science, Juntendo University Graduate School of Medicine, Tokyo, Japan; Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Miki Bundo
- Department of Molecular Brain Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan; Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Brain Science Institute, Wako, Saitama, Japan.
| | - Kazuya Iwamoto
- Department of Molecular Brain Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan; Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Brain Science Institute, Wako, Saitama, Japan.
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Pelinski Y, Hidaoui D, Stolz A, Hermetet F, Chelbi R, Diop MK, Chioukh AM, Porteu F, Elvira-Matelot E. NF-κB signaling controls H3K9me3 levels at intronic LINE-1 and hematopoietic stem cell genes in cis. J Exp Med 2022; 219:213343. [PMID: 35802137 PMCID: PMC9274146 DOI: 10.1084/jem.20211356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 12/23/2021] [Accepted: 06/21/2022] [Indexed: 01/11/2023] Open
Abstract
Ionizing radiations (IR) alter hematopoietic stem cell (HSC) function on the long term, but the mechanisms underlying these effects are still poorly understood. We recently showed that IR induces the derepression of L1Md, the mouse young subfamilies of LINE-1/L1 retroelements. L1 contributes to gene regulatory networks. However, how L1Md are derepressed and impact HSC gene expression are not known. Here, we show that IR triggers genome-wide H3K9me3 decrease that occurs mainly at L1Md. Loss of H3K9me3 at intronic L1Md harboring NF-κB binding sites motifs but not at promoters is associated with the repression of HSC-specific genes. This is correlated with reduced NFKB1 repressor expression. TNF-α treatment rescued all these effects and prevented IR-induced HSC loss of function in vivo. This TNF-α/NF-κB/H3K9me3/L1Md axis might be important to maintain HSCs while allowing expression of immune genes during myeloid regeneration or damage-induced bone marrow ablation.
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Affiliation(s)
- Yanis Pelinski
- INSERM UMR1287, Gustave Roussy, Villejuif, France,Université Paris-Saclay, Gif-sur-Yvette, France
| | - Donia Hidaoui
- INSERM UMR1287, Gustave Roussy, Villejuif, France,Université Paris-Saclay, Gif-sur-Yvette, France
| | - Anne Stolz
- INSERM UMR1287, Gustave Roussy, Villejuif, France,Université Paris-Saclay, Gif-sur-Yvette, France
| | - François Hermetet
- INSERM UMR1287, Gustave Roussy, Villejuif, France,Université Paris-Saclay, Gif-sur-Yvette, France
| | - Rabie Chelbi
- INSERM UMR1287, Gustave Roussy, Villejuif, France,Université Paris-Saclay, Gif-sur-Yvette, France
| | - M’boyba Khadija Diop
- Université Paris-Saclay, Gif-sur-Yvette, France,Bioinformatics Platform UMS AMMICa INSERM US23/CNRS 3655, Gustave Roussy, Villejuif, France
| | - Amir M. Chioukh
- INSERM UMR1287, Gustave Roussy, Villejuif, France,Université Paris-Saclay, Gif-sur-Yvette, France
| | - Françoise Porteu
- INSERM UMR1287, Gustave Roussy, Villejuif, France,Université Paris-Saclay, Gif-sur-Yvette, France
| | - Emilie Elvira-Matelot
- INSERM UMR1287, Gustave Roussy, Villejuif, France,Université Paris-Saclay, Gif-sur-Yvette, France
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The Role of Transposable Elements of the Human Genome in Neuronal Function and Pathology. Int J Mol Sci 2022; 23:ijms23105847. [PMID: 35628657 PMCID: PMC9148063 DOI: 10.3390/ijms23105847] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 12/13/2022] Open
Abstract
Transposable elements (TEs) have been extensively studied for decades. In recent years, the introduction of whole-genome and whole-transcriptome approaches, as well as single-cell resolution techniques, provided a breakthrough that uncovered TE involvement in host gene expression regulation underlying multiple normal and pathological processes. Of particular interest is increased TE activity in neuronal tissue, and specifically in the hippocampus, that was repeatedly demonstrated in multiple experiments. On the other hand, numerous neuropathologies are associated with TE dysregulation. Here, we provide a comprehensive review of literature about the role of TEs in neurons published over the last three decades. The first chapter of the present review describes known mechanisms of TE interaction with host genomes in general, with the focus on mammalian and human TEs; the second chapter provides examples of TE exaptation in normal neuronal tissue, including TE involvement in neuronal differentiation and plasticity; and the last chapter lists TE-related neuropathologies. We sought to provide specific molecular mechanisms of TE involvement in neuron-specific processes whenever possible; however, in many cases, only phenomenological reports were available. This underscores the importance of further studies in this area.
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Jeon S, Kim S, Oh MH, Liang P, Tang W, Han K. A comprehensive analysis of gorilla-specific LINE-1 retrotransposons. Genes Genomics 2021; 43:1133-1141. [PMID: 34406591 DOI: 10.1007/s13258-021-01146-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 07/29/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Long interspersed element-1 (LINE-1 or L1) is the most abundant retrotransposons in the primate genome. They have approximately 520,000 copies and make up ~ 17% of the primate genome. Full-length L1s can mobilize to a new genomic location using their enzymatic machinery. Gorilla is the second closest species to humans after the chimpanzee, and human-gorilla split 7-12 million years ago. The gorilla genome provides an opportunity to explore primate origins and evolution. OBJECTIVE L1s have contributed to genome diversity and variations during primate evolution. This study aimed to identify gorilla-specific L1s using a more recent version of the gorilla reference genome (Mar. 2016 GSMRT3/gorGor5). METHODS We collected gorilla-specific L1 candidates through computational analysis and manual inspection. L1Xplorer was used to identify whether full-length gorilla-specific L1s were intact. In addition, to determine the level of sequence conservation between intact fulllength gorilla-specific L1s, two ORFs of intact L1s were aligned with the L1PA2 consensus sequence. RESULTS 2002 gorilla-specific L1 candidates were identified through computational analysis. Among them, we manually inspected 1,883 gorilla-specific L1s, among which most of them belong to the L1PA2 subfamily and 12 were intact L1s that could influence genomic variations in the gorilla genome. Interestingly, the 12 intact full-length gorilla-specific L1s have 14 highly conserved nonsynonymous mutations, including 6 mutations and 8 mutations in ORF1 and ORF2, respectively. In comparison to the intact full-length chimpanzee-specific L1s and human-specific hot-L1s, two of these in ORF1 (L256F and E293G) were shown as gorilla-specific nonsynonymous mutations. CONCLUSION The gorilla-specific L1s may have had significantly affected the gorilla genome to compose a genome different form that of other primates during primate evolution.
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Affiliation(s)
- Soyeon Jeon
- Department of Microbiology, College of Science and Technology, Dankook University, Cheonan, 31116, Republic of Korea
| | - Songmi Kim
- Department of Microbiology, College of Science and Technology, Dankook University, Cheonan, 31116, Republic of Korea.,Center for Bio-Medical Engineering Core Facility, Dankook University, Cheonan, 31116, Republic of Korea
| | - Man Hwan Oh
- Department of Microbiology, College of Science and Technology, Dankook University, Cheonan, 31116, Republic of Korea
| | - Ping Liang
- Department of Biological Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada.,Centre of Biotechnologies, Brock University, St. Catharines, ON, L2S 3A1, Canada
| | - Wanxiangfu Tang
- Department of Biological Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada
| | - Kyudong Han
- Department of Microbiology, College of Science and Technology, Dankook University, Cheonan, 31116, Republic of Korea. .,Center for Bio-Medical Engineering Core Facility, Dankook University, Cheonan, 31116, Republic of Korea.
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Ciomborowska-Basheer J, Staszak K, Kubiak MR, Makałowska I. Not So Dead Genes-Retrocopies as Regulators of Their Disease-Related Progenitors and Hosts. Cells 2021; 10:cells10040912. [PMID: 33921034 PMCID: PMC8071448 DOI: 10.3390/cells10040912] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 03/30/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022] Open
Abstract
Retroposition is RNA-based gene duplication leading to the creation of single exon nonfunctional copies. Nevertheless, over time, many of these duplicates acquire transcriptional capabilities. In human in most cases, these so-called retrogenes do not code for proteins but function as regulatory long noncoding RNAs (lncRNAs). The mechanisms by which they can regulate other genes include microRNA sponging, modulation of alternative splicing, epigenetic regulation and competition for stabilizing factors, among others. Here, we summarize recent findings related to lncRNAs originating from retrocopies that are involved in human diseases such as cancer and neurodegenerative, mental or cardiovascular disorders. Special attention is given to retrocopies that regulate their progenitors or host genes. Presented evidence from the literature and our bioinformatics analyses demonstrates that these retrocopies, often described as unimportant pseudogenes, are significant players in the cell’s molecular machinery.
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6
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Pócza T, Grolmusz VK, Papp J, Butz H, Patócs A, Bozsik A. Germline Structural Variations in Cancer Predisposition Genes. Front Genet 2021; 12:634217. [PMID: 33936164 PMCID: PMC8081352 DOI: 10.3389/fgene.2021.634217] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 03/08/2021] [Indexed: 12/14/2022] Open
Abstract
In addition to single nucleotide variations and small-scale indels, structural variations (SVs) also contribute to the genetic diversity of the genome. SVs, such as deletions, duplications, amplifications, or inversions may also affect coding regions of cancer-predisposing genes. These rearrangements may abrogate the open reading frame of these genes or adversely affect their expression and may thus act as germline mutations in hereditary cancer syndromes. With the capacity of disrupting the function of tumor suppressors, structural variations confer an increased risk of cancer and account for a remarkable fraction of heritability. The development of sequencing techniques enables the discovery of a constantly growing number of SVs of various types in cancer predisposition genes (CPGs). Here, we provide a comprehensive review of the landscape of germline SV types, detection methods, pathomechanisms, and frequency in CPGs, focusing on the two most common cancer syndromes: hereditary breast- and ovarian cancer and gastrointestinal cancers. Current knowledge about the possible molecular mechanisms driving to SVs is also summarized.
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Affiliation(s)
- Tímea Pócza
- Department of Molecular Genetics, National Institute of Oncology, Budapest, Hungary
| | - Vince Kornél Grolmusz
- Department of Molecular Genetics, National Institute of Oncology, Budapest, Hungary.,Hereditary Cancers Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - János Papp
- Department of Molecular Genetics, National Institute of Oncology, Budapest, Hungary.,Hereditary Cancers Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - Henriett Butz
- Department of Molecular Genetics, National Institute of Oncology, Budapest, Hungary.,Hereditary Cancers Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary.,Department of Laboratory Medicine, Semmelweis University, Budapest, Hungary
| | - Attila Patócs
- Department of Molecular Genetics, National Institute of Oncology, Budapest, Hungary.,Hereditary Cancers Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary.,Department of Laboratory Medicine, Semmelweis University, Budapest, Hungary
| | - Anikó Bozsik
- Department of Molecular Genetics, National Institute of Oncology, Budapest, Hungary.,Hereditary Cancers Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
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7
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Linker SB, Randolph-Moore L, Kottilil K, Qiu F, Jaeger BN, Barron J, Gage FH. Identification of bona fide B2 SINE retrotransposon transcription through single-nucleus RNA-seq of the mouse hippocampus. Genome Res 2020; 30:1643-1654. [PMID: 33122305 PMCID: PMC7605253 DOI: 10.1101/gr.262196.120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 09/29/2020] [Indexed: 12/21/2022]
Abstract
Currently, researchers rely on generalized methods to quantify transposable element (TE) RNA expression, such as RT-qPCR and RNA-seq, that do not distinguish between TEs expressed from their own promoter (bona fide) and TEs that are transcribed from a neighboring gene promoter such as within an intron or exon. This distinction is important owing to the differing functional roles of TEs depending on whether they are independently transcribed. Here we report a simple strategy to examine bona fide TE expression, termed BonaFide-TEseq. This approach can be used with any template-switch based library such as Smart-seq2 or the single-cell 5′ gene expression kit from 10x, extending its utility to single-cell RNA-sequencing. This approach does not require TE-specific enrichment, enabling the simultaneous examination of TEs and protein-coding genes. We show that TEs identified through BonaFide-TEseq are expressed from their own promoter, rather than captured as internal products of genes. We reveal the utility of BonaFide-TEseq in the analysis of single-cell data and show that short-interspersed nuclear elements (SINEs) show cell type–specific expression profiles in the mouse hippocampus. We further show that, in response to a brief exposure of home-cage mice to a novel stimulus, SINEs are activated in dentate granule neurons in a time course that is similar to that of protein-coding immediate early genes. This work provides a simple alternative approach to assess bona fide TE transcription at single-cell resolution and provides a proof-of-concept using this method to identify SINE activation in a context that is relevant for normal learning and memory.
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Affiliation(s)
- Sara B Linker
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Lynne Randolph-Moore
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Kalyani Kottilil
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Fan Qiu
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Baptiste N Jaeger
- Laboratory of Neural Plasticity, Faculty of Medicine and Science, Brain Research Institute, University of Zurich, 8057 Zurich, Switzerland
| | - Jerika Barron
- Biomedical Sciences Graduate Program, University of California, San Francisco, San Francisco, California 94143, USA
| | - Fred H Gage
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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Complex Analysis of Retroposed Genes' Contribution to Human Genome, Proteome and Transcriptome. Genes (Basel) 2020; 11:genes11050542. [PMID: 32408516 PMCID: PMC7290577 DOI: 10.3390/genes11050542] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/06/2020] [Accepted: 05/08/2020] [Indexed: 02/07/2023] Open
Abstract
Gene duplication is a major driver of organismal evolution. One of the main mechanisms of gene duplications is retroposition, a process in which mRNA is first transcribed into DNA and then reintegrated into the genome. Most gene retrocopies are depleted of the regulatory regions. Nevertheless, examples of functional retrogenes are rapidly increasing. These functions come from the gain of new spatio-temporal expression patterns, imposed by the content of the genomic sequence surrounding inserted cDNA and/or by selectively advantageous mutations, which may lead to the switch from protein coding to regulatory RNA. As recent studies have shown, these genes may lead to new protein domain formation through fusion with other genes, new regulatory RNAs or other regulatory elements. We utilized existing data from high-throughput technologies to create a complex description of retrogenes functionality. Our analysis led to the identification of human retroposed genes that substantially contributed to transcriptome and proteome. These retrocopies demonstrated the potential to encode proteins or short peptides, act as cis- and trans- Natural Antisense Transcripts (NATs), regulate their progenitors’ expression by competing for the same microRNAs, and provide a sequence to lncRNA and novel exons to existing protein-coding genes. Our study also revealed that retrocopies, similarly to retrotransposons, may act as recombination hot spots. To our best knowledge this is the first complex analysis of these functions of retrocopies.
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9
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Gallop Racing Shifts Mature mRNA towards Introns: Does Exercise-Induced Stress Enhance Genome Plasticity? Genes (Basel) 2020; 11:genes11040410. [PMID: 32283859 PMCID: PMC7230505 DOI: 10.3390/genes11040410] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/26/2020] [Accepted: 04/07/2020] [Indexed: 12/25/2022] Open
Abstract
Physical exercise is universally recognized as stressful. Among the "sport species", the horse is probably the most appropriate model for investigating the genomic response to stress due to the homogeneity of its genetic background. The aim of this work is to dissect the whole transcription modulation in Peripheral Blood Mononuclear Cells (PBMCs) after exercise with a time course framework focusing on unexplored regions related to introns and intergenic portions. PBMCs NGS from five 3 year old Sardinian Anglo-Arab racehorses collected at rest and after a 2000 m race was performed. Apart from differential gene expression ascertainment between the two time points the complexity of transcription for alternative transcripts was identified. Interestingly, we noted a transcription shift from the coding to the non-coding regions. We further investigated the possible causes of this phenomenon focusing on genomic repeats, using a differential expression approach and finding a strong general up-regulation of repetitive elements such as LINE. Since their modulation is also associated with the "exonization", the recruitment of repeats that act with regulatory functions, suggesting that there might be an active regulation of this transcriptional shift. Thanks to an innovative bioinformatic approach, our study could represent a model for the transcriptomic investigation of stress.
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Shapiro JA. Living Organisms Author Their Read-Write Genomes in Evolution. BIOLOGY 2017; 6:E42. [PMID: 29211049 PMCID: PMC5745447 DOI: 10.3390/biology6040042] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 11/17/2017] [Accepted: 11/28/2017] [Indexed: 12/18/2022]
Abstract
Evolutionary variations generating phenotypic adaptations and novel taxa resulted from complex cellular activities altering genome content and expression: (i) Symbiogenetic cell mergers producing the mitochondrion-bearing ancestor of eukaryotes and chloroplast-bearing ancestors of photosynthetic eukaryotes; (ii) interspecific hybridizations and genome doublings generating new species and adaptive radiations of higher plants and animals; and, (iii) interspecific horizontal DNA transfer encoding virtually all of the cellular functions between organisms and their viruses in all domains of life. Consequently, assuming that evolutionary processes occur in isolated genomes of individual species has become an unrealistic abstraction. Adaptive variations also involved natural genetic engineering of mobile DNA elements to rewire regulatory networks. In the most highly evolved organisms, biological complexity scales with "non-coding" DNA content more closely than with protein-coding capacity. Coincidentally, we have learned how so-called "non-coding" RNAs that are rich in repetitive mobile DNA sequences are key regulators of complex phenotypes. Both biotic and abiotic ecological challenges serve as triggers for episodes of elevated genome change. The intersections of cell activities, biosphere interactions, horizontal DNA transfers, and non-random Read-Write genome modifications by natural genetic engineering provide a rich molecular and biological foundation for understanding how ecological disruptions can stimulate productive, often abrupt, evolutionary transformations.
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Affiliation(s)
- James A Shapiro
- Department of Biochemistry and Molecular Biology, University of Chicago GCIS W123B, 979 E. 57th Street, Chicago, IL 60637, USA.
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11
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Kannan M, Li J, Fritz SE, Husarek KE, Sanford JC, Sullivan TL, Tiwary PK, An W, Boeke JD, Symer DE. Dynamic silencing of somatic L1 retrotransposon insertions reflects the developmental and cellular contexts of their genomic integration. Mob DNA 2017; 8:8. [PMID: 28491150 PMCID: PMC5424313 DOI: 10.1186/s13100-017-0091-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 05/03/2017] [Indexed: 02/15/2023] Open
Abstract
Background The ongoing mobilization of mammalian transposable elements (TEs) contributes to natural genetic variation. To survey the epigenetic control and expression of reporter genes inserted by L1 retrotransposition in diverse cellular and genomic contexts, we engineered highly sensitive, real-time L1 retrotransposon reporter constructs. Results Here we describe different patterns of expression and epigenetic controls of newly inserted sequences retrotransposed by L1 in various somatic cells and tissues including cultured human cancer cells, mouse embryonic stem cells, and tissues of pseudofounder transgenic mice and their progeny. In cancer cell lines, the newly inserted sequences typically underwent rapid transcriptional gene silencing, but they lacked cytosine methylation even after many cell divisions. L1 reporter expression was reversible and oscillated frequently. Silenced or variegated reporter expression was strongly and uniformly reactivated by treatment with inhibitors of histone deacetylation, revealing the mechanism for their silencing. By contrast, de novo integrants retrotransposed by L1 in pluripotent mouse embryonic stem (ES) cells underwent rapid silencing by dense cytosine methylation. Similarly, de novo cytosine methylation also was identified at new integrants when studied in several distinct somatic tissues of adult founder mice. Pre-existing L1 elements in cultured human cancer cells were stably silenced by dense cytosine methylation, whereas their transcription modestly increased when cytosine methylation was experimentally reduced in cells lacking DNA methyltransferases DNMT1 and DNMT3b. As a control, reporter genes mobilized by piggyBac (PB), a DNA transposon, revealed relatively stable and robust expression without apparent silencing in both cultured cancer cells and ES cells. Conclusions We hypothesize that the de novo methylation marks at newly inserted sequences retrotransposed by L1 in early pre-implantation development are maintained or re-established in adult somatic tissues. By contrast, histone deacetylation reversibly silences L1 reporter insertions that had mobilized at later timepoints in somatic development and differentiation, e.g., in cancer cell lines. We conclude that the cellular contexts of L1 retrotransposition can determine expression or silencing of newly integrated sequences. We propose a model whereby reporter expression from somatic TE insertions reflects the timing, molecular mechanism, epigenetic controls and the genomic, cellular and developmental contexts of their integration. Electronic supplementary material The online version of this article (doi:10.1186/s13100-017-0091-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Manoj Kannan
- Department of Biological Sciences, Birla Institute of Technology and Science Pilani, Pilani, 333031 Rajasthan India.,Laboratory of Immunobiology, Mouse Cancer Genetics Program and Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702 USA.,Present Address: Birla Institute of Technology and Science, Pilani, Dubai campus, Dubai, United Arab Emirates
| | - Jingfeng Li
- Laboratory of Immunobiology, Mouse Cancer Genetics Program and Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702 USA.,Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH USA.,Department of Internal Medicine, The Ohio State University, Columbus, OH USA
| | - Sarah E Fritz
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH USA.,Present Address: National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD USA
| | - Kathryn E Husarek
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH USA.,Present Address: Aventiv Research, Inc., Columbus, OH USA
| | - Jonathan C Sanford
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH USA.,Present Address: Drug Safety Research and Development, Pfizer, Inc., Groton, CT USA
| | - Teresa L Sullivan
- Laboratory of Immunobiology, Mouse Cancer Genetics Program and Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702 USA
| | - Pawan Kumar Tiwary
- Laboratory of Immunobiology, Mouse Cancer Genetics Program and Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702 USA.,Present Address: Biocon, Bangalore, India
| | - Wenfeng An
- Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, Baltimore, MD USA.,Present Address: Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD USA
| | - Jef D Boeke
- Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, Baltimore, MD USA.,Present Address: Institute for Systems Genetics, New York University Langone Medical Center, New York, NY USA
| | - David E Symer
- Laboratory of Immunobiology, Mouse Cancer Genetics Program and Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702 USA.,Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH USA.,Human Cancer Genetics Program, and Department of Biomedical Informatics, The Ohio State University, Columbus, OH USA.,Human Cancer Genetics Program, Department of Cancer Biology and Genetics, and Department of Biomedical Informatics, The Ohio State University, Tzagournis Research Facility, Room 440, 420 West 12th Ave, Columbus, OH 43210 USA
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12
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Protein-Coding Genes' Retrocopies and Their Functions. Viruses 2017; 9:v9040080. [PMID: 28406439 PMCID: PMC5408686 DOI: 10.3390/v9040080] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Revised: 04/07/2017] [Accepted: 04/11/2017] [Indexed: 12/11/2022] Open
Abstract
Transposable elements, often considered to be not important for survival, significantly contribute to the evolution of transcriptomes, promoters, and proteomes. Reverse transcriptase, encoded by some transposable elements, can be used in trans to produce a DNA copy of any RNA molecule in the cell. The retrotransposition of protein-coding genes requires the presence of reverse transcriptase, which could be delivered by either non-long terminal repeat (non-LTR) or LTR transposons. The majority of these copies are in a state of “relaxed” selection and remain “dormant” because they are lacking regulatory regions; however, many become functional. In the course of evolution, they may undergo subfunctionalization, neofunctionalization, or replace their progenitors. Functional retrocopies (retrogenes) can encode proteins, novel or similar to those encoded by their progenitors, can be used as alternative exons or create chimeric transcripts, and can also be involved in transcriptional interference and participate in the epigenetic regulation of parental gene expression. They can also act in trans as natural antisense transcripts, microRNA (miRNA) sponges, or a source of various small RNAs. Moreover, many retrocopies of protein-coding genes are linked to human diseases, especially various types of cancer.
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13
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Coates BS, Abel CA, Perera OP. Estimation of long terminal repeat element content in the Helicoverpa zea genome from high-throughput sequencing of bacterial artificial chromosome pools. Genome 2016; 60:310-324. [PMID: 28177843 DOI: 10.1139/gen-2016-0067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The lepidopteran pest insect Helicoverpa zea feeds on cultivated corn and cotton across the Americas where control remains challenging owing to the evolution of resistance to chemical and transgenic insecticidal toxins, yet genomic resources remain scarce for this species. A bacterial artificial chromosome (BAC) library having a mean genomic insert size of 145 ± 20 kbp was created from a laboratory strain of H. zea, which provides ∼12.9-fold coverage of a 362.8 ± 8.8 Mbp (0.37 ± 0.09 pg) flow cytometry estimated haploid genome size. Assembly of Illumina HiSeq 2000 reads generated from 14 pools that encompassed all BAC clones resulted in 165 485 genomic contigs (N50 = 3262 bp; 324.6 Mbp total). Long terminal repeat (LTR) protein coding regions annotated from 181 contigs included 30 Ty1/copia, 78 Ty3/gypsy, and 73 BEL/Pao elements, of which 60 (33.1%) encoded all five functional polyprotein (pol) domains. Approximately 14% of LTR elements are distributed non-randomly across pools of BAC clones.
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Affiliation(s)
- Brad S Coates
- a USDA-ARS, Corn Insects & Crop Genetics Research Unit, Genetics Laboratory, Iowa State University, Ames, IA 50011, USA.,b Department of Entomology, Iowa State University, Ames, IA 50011, USA
| | - Craig A Abel
- a USDA-ARS, Corn Insects & Crop Genetics Research Unit, Genetics Laboratory, Iowa State University, Ames, IA 50011, USA
| | - Omaththage P Perera
- c USDA-ARS, Southern Insect Management Research Unit, 141 Experiment Station Road, P.O. Box 346, Stoneville, MS 38776, USA
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14
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Tee MK, Speek M, Legeza B, Modi B, Teves ME, McAllister JM, Strauss JF, Miller WL. Alternative splicing of DENND1A, a PCOS candidate gene, generates variant 2. Mol Cell Endocrinol 2016; 434:25-35. [PMID: 27297658 PMCID: PMC4983473 DOI: 10.1016/j.mce.2016.06.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 06/03/2016] [Accepted: 06/05/2016] [Indexed: 12/26/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a common endocrinopathy characterized by hyperandrogenism and metabolic disorders. The excess androgens may be of both ovarian and adrenal origin. PCOS has a strong genetic component, and genome-wide association studies have identified several candidate genes, notably DENND1A, which encodes connecdenn 1, involved in trafficking of endosomes. DENND1A encodes two principal variants, V1 (1009 amino acids) and V2 (559 amino acids). The androgen-producing ovarian theca cells of PCOS women over-express V2. Knockdown of V2 in these cells reduces androgen production, and overexpression of V2 in normal theca cells confers upon them a PCOS phenotype of increased androgen synthesis. We report that human adrenal NCI-H295A cells express V1 and V2 mRNA and that the V2 isoform is produced by exonization of sequences in intron 20, which generates a unique exon 20A, encoding the C-terminus of V2. As in human theca cells from normal women, forced expression of V2 in NCI-H295A cells resulted in increased abundance of CYP17A1 and CYP11A1 mRNAs. We also found genetic variation in the intronic region 330 bp upstream from exon 20A, which could have the potential to drive the selective expression of V2. There was no clear association with these variants with PCOS when we analyzed genomc DNA from normal women and women with PCOS. Using minigene expression vectors in NCI-H295A cells, this variable region did not consistently favor splicing of the V2 transcript. These findings suggest increased V2 expression in PCOS theca cells is not the result of genomic sequence variation in intron 20.
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Affiliation(s)
- Meng Kian Tee
- Department of Pediatrics and the Center for Reproductive Sciences, University of California, San Francisco, United States
| | - Mart Speek
- Department of Pediatrics and the Center for Reproductive Sciences, University of California, San Francisco, United States
| | - Balázs Legeza
- Department of Pediatrics and the Center for Reproductive Sciences, University of California, San Francisco, United States
| | - Bhavi Modi
- Department of Obstetrics and Gynecology, Virginia Commonwealth University, Richmond, VA 23298, United States; Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Maria Eugenia Teves
- Department of Obstetrics and Gynecology, Virginia Commonwealth University, Richmond, VA 23298, United States; Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Janette M McAllister
- Department of Pathology, Pennsylvania State College of Medicine, Hershey, PA 17033, United States; Department of Obstetrics and Gynecology, Pennsylvania State College of Medicine, Hershey, PA 17033, United States
| | - Jerome F Strauss
- Department of Obstetrics and Gynecology, Virginia Commonwealth University, Richmond, VA 23298, United States; Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Walter L Miller
- Department of Pediatrics and the Center for Reproductive Sciences, University of California, San Francisco, United States.
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15
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[Letter to the Editor] Accelerated RNA-RNA hybridization by concentrated guanidinium thiocyanate solution in single-step RNA isolation. Biotechniques 2016; 61:61-5. [PMID: 27528070 DOI: 10.2144/000114441] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 05/09/2016] [Indexed: 11/23/2022] Open
Abstract
Address correspondence to Mart Speek, Department of Gene Technology, Akadeemia tee 15, Room 129, Tallinn University of Technology, Tallinn 19086, Estonia. E-mail: mart.speek@ttu.ee.
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16
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Criscione SW, Theodosakis N, Micevic G, Cornish TC, Burns KH, Neretti N, Rodić N. Genome-wide characterization of human L1 antisense promoter-driven transcripts. BMC Genomics 2016; 17:463. [PMID: 27301971 PMCID: PMC4908685 DOI: 10.1186/s12864-016-2800-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 05/26/2016] [Indexed: 11/23/2022] Open
Abstract
Background Long INterspersed Element-1 (LINE-1 or L1) is the only autonomously active, transposable element in the human genome. L1 sequences comprise approximately 17 % of the human genome, but only the evolutionarily recent, human-specific subfamily is retrotransposition competent. The L1 promoter has a bidirectional orientation containing a sense promoter that drives the transcription of two proteins required for retrotransposition and an antisense promoter. The L1 antisense promoter can drive transcription of chimeric transcripts: 5’ L1 antisense sequences spliced to the exons of neighboring genes. Results The impact of L1 antisense promoter activity on cellular transcriptomes is poorly understood. To investigate this, we analyzed GenBank ESTs for messenger RNAs that initiate in the L1 antisense promoter. We identified 988 putative L1 antisense chimeric transcripts, 911 of which have not been previously reported. These appear to be alternative genic transcripts, sense-oriented with respect to gene and initiating near, but typically downstream of, the gene transcriptional start site. In multiple cell lines, L1 antisense promoters display enrichment for YY1 transcription factor and histone modifications associated with active promoters. Global run-on sequencing data support the activity of the L1 antisense promoter. We independently detected 124 L1 antisense chimeric transcripts using long read Pacific Biosciences RNA-seq data. Furthermore, we validated four chimeric transcripts by quantitative RT-PCR and Sanger sequencing and demonstrated that they are readily detectable in many normal human tissues. Conclusions We present a comprehensive characterization of human L1 antisense promoter-driven transcripts and provide substantial evidence that they are transcribed in a variety of human cell-types. Our findings reveal a new wide-reaching aspect of L1 biology by identifying antisense transcripts affecting as many as 4 % of all human genes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2800-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Steven W Criscione
- Department of Molecular Biology, Cell Biology, and Biochemistry, Center for Computational Molecular Biology, Brown University, Providence, RI, 02912, USA
| | - Nicholas Theodosakis
- Department of Pathology, Yale University, New Haven, CT, 06510, USA.,Department of Dermatology, Division of Dermatopathology, Yale University, New Haven, CT, 06510, USA
| | - Goran Micevic
- Department of Pathology, Yale University, New Haven, CT, 06510, USA.,Department of Dermatology, Division of Dermatopathology, Yale University, New Haven, CT, 06510, USA
| | - Toby C Cornish
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Kathleen H Burns
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,High Throughput (HiT) Biology Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nicola Neretti
- Department of Molecular Biology, Cell Biology, and Biochemistry, Center for Computational Molecular Biology, Brown University, Providence, RI, 02912, USA.
| | - Nemanja Rodić
- Department of Pathology, Yale University, New Haven, CT, 06510, USA. .,Department of Dermatology, Division of Dermatopathology, Yale University, New Haven, CT, 06510, USA.
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17
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Gu Z, Jin K, Crabbe MJC, Zhang Y, Liu X, Huang Y, Hua M, Nan P, Zhang Z, Zhong Y. Enrichment analysis of Alu elements with different spatial chromatin proximity in the human genome. Protein Cell 2016; 7:250-266. [PMID: 26861146 PMCID: PMC4818845 DOI: 10.1007/s13238-015-0240-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 11/24/2015] [Indexed: 02/03/2023] Open
Abstract
Transposable elements (TEs) have no longer been totally considered as “junk DNA” for quite a time since the continual discoveries of their multifunctional roles in eukaryote genomes. As one of the most important and abundant TEs that still active in human genome, Alu, a SINE family, has demonstrated its indispensable regulatory functions at sequence level, but its spatial roles are still unclear. Technologies based on 3C (chromosome conformation capture) have revealed the mysterious three-dimensional structure of chromatin, and make it possible to study the distal chromatin interaction in the genome. To find the role TE playing in distal regulation in human genome, we compiled the new released Hi-C data, TE annotation, histone marker annotations, and the genome-wide methylation data to operate correlation analysis, and found that the density of Alu elements showed a strong positive correlation with the level of chromatin interactions (hESC: r = 0.9, P < 2.2 × 1016; IMR90 fibroblasts: r = 0.94, P < 2.2 × 1016) and also have a significant positive correlation with some remote functional DNA elements like enhancers and promoters (Enhancer: hESC: r = 0.997, P = 2.3 × 10−4; IMR90: r = 0.934, P = 2 × 10−2; Promoter: hESC: r = 0.995, P = 3.8 × 10−4; IMR90: r = 0.996, P = 3.2 × 10−4). Further investigation involving GC content and methylation status showed the GC content of Alu covered sequences shared a similar pattern with that of the overall sequence, suggesting that Alu elements also function as the GC nucleotide and CpG site provider. In all, our results suggest that the Alu elements may act as an alternative parameter to evaluate the Hi-C data, which is confirmed by the correlation analysis of Alu elements and histone markers. Moreover, the GC-rich Alu sequence can bring high GC content and methylation flexibility to the regions with more distal chromatin contact, regulating the transcription of tissue-specific genes.
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Affiliation(s)
- Zhuoya Gu
- School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Ke Jin
- Banting and Best Department of Medical Research, Donnelly Centre, University of Toronto, Toronto, ON, M5S 1A1, Canada
| | - M James C Crabbe
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford, OX1 3PS, UK
- Institute of Biomedical and Environmental Science & Technology, Department of Life Sciences, University of Bedfordshire, Park Square, Luton, LU1 3JU, UK
| | - Yang Zhang
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Champaign, IL, 61801, USA
| | - Xiaolin Liu
- School of Public Health, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Yanyan Huang
- School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Mengyi Hua
- School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Peng Nan
- School of Life Sciences, Fudan University, Shanghai, 200433, China.
| | - Zhaolei Zhang
- Banting and Best Department of Medical Research, Donnelly Centre, University of Toronto, Toronto, ON, M5S 1A1, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S 1A1, Canada.
| | - Yang Zhong
- School of Life Sciences, Fudan University, Shanghai, 200433, China.
- Institute of Biodiversity Science and Institute of High Altitude Medicine, Tibet University, Lhasa, 850012, China.
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18
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LINE-1 in cancer: multifaceted functions and potential clinical implications. Genet Med 2015; 18:431-9. [DOI: 10.1038/gim.2015.119] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 07/16/2015] [Indexed: 12/15/2022] Open
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19
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Kaer K, Speek M. Intronic retroelements: Not just "speed bumps" for RNA polymerase II. Mob Genet Elements 2014; 2:154-157. [PMID: 23061024 PMCID: PMC3463474 DOI: 10.4161/mge.20774] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Two well-known retroelements, L1 and Alu, comprise about one third of the human genome and are nearly equally distributed between the intergenic and intragenic regions. They carry different regulatory elements and contribute structurally and functionally to the expression of our genes. Recent data also suggest that hundreds of intronic L1s and Alus interfere with the transcription of human genes by inducing intron retention, forcing exonization and cryptic polyadenylation. These novel features can be explained with the RNA polymerase kinetic model and suggest that intronic L1s and Alus are not just "speed bumps" in regulation of RNA polymerase traffic. Here we discuss the complexity of the regulation of gene transcription imposed by intronic retroelements and predict that in addition to transcriptional activity, transcription factor binding and nucleosomal occupancy play a significant role in the transcriptional interference effects of the host genes.
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Affiliation(s)
- Kristel Kaer
- Department of Gene Technology; Tallinn University of Technology; Tallinn, Estonia
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20
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Abstract
Discoveries in cytogenetics, molecular biology, and genomics have revealed that genome change is an active cell-mediated physiological process. This is distinctly at variance with the pre-DNA assumption that genetic changes arise accidentally and sporadically. The discovery that DNA changes arise as the result of regulated cell biochemistry means that the genome is best modelled as a read-write (RW) data storage system rather than a read-only memory (ROM). The evidence behind this change in thinking and a consideration of some of its implications are the subjects of this article. Specific points include the following: cells protect themselves from accidental genome change with proofreading and DNA damage repair systems; localized point mutations result from the action of specialized trans-lesion mutator DNA polymerases; cells can join broken chromosomes and generate genome rearrangements by non-homologous end-joining (NHEJ) processes in specialized subnuclear repair centres; cells have a broad variety of natural genetic engineering (NGE) functions for transporting, diversifying and reorganizing DNA sequences in ways that generate many classes of genomic novelties; natural genetic engineering functions are regulated and subject to activation by a range of challenging life history events; cells can target the action of natural genetic engineering functions to particular genome locations by a range of well-established molecular interactions, including protein binding with regulatory factors and linkage to transcription; and genome changes in cancer can usefully be considered as consequences of the loss of homeostatic control over natural genetic engineering functions.
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Affiliation(s)
- James A Shapiro
- Department of Biochemistry and Molecular Biology, University of Chicago, GCISW123B, 979 E. 57th Street, Chicago, IL 60637, USA
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21
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Lee YCG, Chang HH. The evolution and functional significance of nested gene structures in Drosophila melanogaster. Genome Biol Evol 2014; 5:1978-85. [PMID: 24084778 PMCID: PMC3814207 DOI: 10.1093/gbe/evt149] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Nearly 10% of the genes in the genome of Drosophila melanogaster are in nested structures, in which one gene is completely nested within the intron of another gene (nested and including gene, respectively). Even though the coding sequences and untranslated regions of these nested/including gene pairs do not overlap, their intimate structures and the possibility of shared regulatory sequences raise questions about the evolutionary forces governing the origination and subsequent functional and evolutionary impacts of these structures. In this study, we show that nested genes experience weaker evolutionary constraint, have faster rates of protein evolution, and are expressed in fewer tissues than other genes, while including genes show the opposite patterns. Surprisingly, despite completely overlapping with each other, nested and including genes are less likely to display correlated gene expression and biological function than the nearby yet nonoverlapping genes. Interestingly, significantly fewer nested genes are transcribed from the same strand as the including gene. We found that same-strand nested genes are more likely to be single-exon genes. In addition, same-strand including genes are less likely to have known lethal or sterile phenotypes than opposite-strand including genes only when the corresponding nested genes have introns. These results support our hypothesis that selection against potential erroneous mRNA splicing when nested and including genes are on the same strand plays an important role in the evolution of nested gene structures.
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Affiliation(s)
- Yuh Chwen G Lee
- Center for Population Biology and Department of Evolution and Ecology, University of California
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22
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Li J, Kannan M, Trivett AL, Liao H, Wu X, Akagi K, Symer DE. An antisense promoter in mouse L1 retrotransposon open reading frame-1 initiates expression of diverse fusion transcripts and limits retrotransposition. Nucleic Acids Res 2014; 42:4546-62. [PMID: 24493738 PMCID: PMC3985663 DOI: 10.1093/nar/gku091] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Between 6 and 30% of human and mouse transcripts are initiated from transposable elements. However, the promoters driving such transcriptional activity are mostly unknown. We experimentally characterized an antisense (AS) promoter in mouse L1 retrotransposons for the first time, oriented antiparallel to the coding strand of L1 open reading frame-1. We found that AS transcription is mediated by RNA polymerase II. Rapid amplification of cDNA ends cloning mapped transcription start sites adjacent to the AS promoter. We identified >100 novel fusion transcripts, of which many were conserved across divergent mouse lineages, suggesting conservation of potential functions. To evaluate whether AS L1 transcription could regulate L1 retrotransposition, we replaced portions of native open reading frame-1 in donor elements by synonymously recoded sequences. The resulting L1 elements lacked AS promoter activity and retrotransposed more frequently than endogenous L1s. Overexpression of AS L1 transcripts also reduced L1 retrotransposition. This suppression of retrotransposition was largely independent of Dicer. Our experiments shed new light on how AS fusion transcripts are initiated from endogenous L1 elements across the mouse genome. Such AS transcription can contribute substantially both to natural transcriptional variation and to endogenous regulation of L1 retrotransposition.
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Affiliation(s)
- Jingfeng Li
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, OH 43210, USA, Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA, Laboratory of Molecular Technology, Advanced Technology Program, SAIC-Frederick, Inc., Frederick, MD 21702, USA, Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA, Human Cancer Genetics Program, The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA, Internal Medicine, The Ohio State University, Columbus, OH 43210, USA and Biomedical Informatics, The Ohio State University, Columbus, OH 43210, USA
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23
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Proliferation and copy number variation of BEL-like long terminal repeat retrotransposons within the Diabrotica virgifera virgifera genome. Gene 2014. [DOI: 10.1016/j.gene.2013.09.100] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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24
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Linker S, Hedges D. Linear decay of retrotransposon antisense bias across genes is contingent upon tissue specificity. PLoS One 2013; 8:e79402. [PMID: 24244495 PMCID: PMC3828378 DOI: 10.1371/journal.pone.0079402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 09/28/2013] [Indexed: 12/23/2022] Open
Abstract
Retrotransposons comprise approximately half of the human genome and contribute to chromatin structure, regulatory motifs, and protein-coding sequences. Since retrotransposon insertions can disrupt functional genetic elements as well as introduce new sequence motifs to a region, they have the potential to affect the function of genes that harbour insertions as well as those nearby. Partly as a result of these effects, the distribution of retrotransposons across the genome is non-uniform and there are observed imbalances in the orientation of insertions with respect to the transcriptional direction of the containing gene. Although some of the factors underlying the observed distributions are understood, much of the variability remains unexplained. Detailed characterization of retrotransposon density in genes could help inform predictions of the functional consequence of de novo as well as polymorphic insertions. In order to characterize the relationship between genes and inserted elements, we have examined the distribution of retrotransposons and their internal motifs within tissue-specific and housekeeping genes. We have identified that the previously established retrotransposon antisense bias decays at a linear rate across genes, resulting in an equal density of sense and antisense retrotransposons near the 3'-UTR. In addition, the decay of antisense bias across genes is less pronounced among tissue-specific genes. Our results provide support for the scenario in which this linear decay in antisense bias is established by natural selection shortly after retrotransposon integration, and that total antisense bias observed is above and beyond any bias introduced by the integration process itself. Finally, we provide an example of a retrotransposon acting as an eQTL on a coincident gene, highlighting one of several possible avenues through which insertions may modulate gene function.
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Affiliation(s)
- Sara Linker
- Hussman Institute for Human Genomics, Dr John T. Macdonald Foundation Department of Human Genetics, Miller School of Medicine, University of Miami, Miami, Florida, United States of America
| | - Dale Hedges
- Division of Human Genetics, Department of Internal Medicine, The Ohio State University, Columbus, Ohio, United States of America
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25
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Tufarelli C, Cruickshanks HA, Meehan RR. LINE-1 activation and epigenetic silencing of suppressor genes in cancer: Causally related events? Mob Genet Elements 2013; 3:e26832. [PMID: 24251074 DOI: 10.4161/mge.26832] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 10/11/2013] [Accepted: 10/15/2013] [Indexed: 01/11/2023] Open
Abstract
The ability of active retrotransposon elements to move within the host genome and alter gene expression with subsequent phenotypic variation led to their initial discovery. In recent years it has become apparent that these elements can also modulate host gene expression independently of their transposition activity. Many retrotransposons maintain endogenous promoter motifs that can potentially drive expression of adjacent DNA modules. Similarly to transposition dependent dysregulation, these proto-promoters can progress disease states when active. Indeed aberrant activation of retrotransposon derived promoters in cancer can lead to transcription of oncogenic isoforms of cellular genes. Here we propose that activation of promoters of transposable elements in cancer can also drive transcription of long non-coding RNAs whose expression leads to silencing of linked tumor suppressor genes. Such transcription driven by aberrantly active transposable elements in cancer can lead to a characteristic reprogramming of epigenetic profiles, thus extending the potential molecular mechanisms whereby retrotransposons can directly contribute to cancer development and subsequent progression.
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Affiliation(s)
- Cristina Tufarelli
- School of Medicine; University of Nottingham; Royal Derby Hospital Centre; Derby, England UK ; Centre for Genetics and Genomics; University of Nottingham; Nottingham, England UK
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26
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Retroelements in human disease. Gene 2013; 518:231-41. [PMID: 23333607 DOI: 10.1016/j.gene.2013.01.008] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 12/28/2012] [Accepted: 01/02/2013] [Indexed: 12/16/2022]
Abstract
Retroelements are an abundant class of noncoding DNAs present in about half of the human genome. Among them, L1, Alu and SVA are currently active. They "jump" by retrotransposition, shuffle genomic regions by 5' and 3' transduction, and promote or inhibit gene transcription by providing alternative promoters or generating antisense and/or regulatory noncoding RNAs. Recent data also suggest that retroelement insertions into exons and introns of genes induce different types of genetic disease, including cancer. Retroelements interfere with the expression of genes by inducing alternative splicing via exon skipping and exonization using cryptic splice sites, and by providing polyadenylation signals. Here we summarize our current understanding of the molecular mechanisms of retroelement-induced mutagenesis which causes fifty different types of human disease. We categorize these mutagenic effects according to eleven different mechanisms and show that most of them may be explained either by traditional exon definition or transcriptional interference, a previously unrecognized molecular mechanism. In summary, this review gives an overview of retroelement insertions in genes that cause significant changes in their transcription and cotranscriptional splicing and show a remarkable level of complexity.
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27
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Kim YJ, Lee J, Han K. Transposable Elements: No More 'Junk DNA'. Genomics Inform 2012; 10:226-33. [PMID: 23346034 PMCID: PMC3543922 DOI: 10.5808/gi.2012.10.4.226] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 11/16/2012] [Accepted: 11/17/2012] [Indexed: 01/03/2023] Open
Abstract
Since the advent of whole-genome sequencing, transposable elements (TEs), just thought to be 'junk' DNA, have been noticed because of their numerous copies in various eukaryotic genomes. Many studies about TEs have been conducted to discover their functions in their host genomes. Based on the results of those studies, it has been generally accepted that they have a function to cause genomic and genetic variations. However, their infinite functions are not fully elucidated. Through various mechanisms, including de novo TE insertions, TE insertion-mediated deletions, and recombination events, they manipulate their host genomes. In this review, we focus on Alu, L1, human endogenous retrovirus, and short interspersed element/variable number of tandem repeats/Alu (SVA) elements and discuss how they have affected primate genomes, especially the human and chimpanzee genomes, since their divergence.
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Affiliation(s)
- Yun-Ji Kim
- Department of Nanobiomedical Science, WCU Research Center, Dankook University, Cheonan 330-714, Korea
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Yao S, Ireland SJ, Bee A, Beesley C, Forootan SS, Dodson A, Dickinson T, Gerard P, Lian LY, Risk JM, Smith P, Malki MI, Ke Y, Cooper CS, Gosden C, Foster CS. Splice variant PRKC-ζ(-PrC) is a novel biomarker of human prostate cancer. Br J Cancer 2012; 107:388-99. [PMID: 22644296 PMCID: PMC3394965 DOI: 10.1038/bjc.2012.162] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 02/24/2012] [Accepted: 03/25/2012] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Previously, using gene-knockdown techniques together with genome expression array analysis, we showed the gene protein Kinase C (PKC)-zeta (PRKCZ) to mediate the malignant phenotype of human prostate cancer. However, according to NCBI, the gene has undergone several major iterations. Therefore, to understand the relationship between its structure and biological activities, we have analysed its expressed sequence in prostate cancer cell lines and tissues. METHODS Transcriptome-walking and targeted PCR were used to sequence the mRNA transcribed from PRKCZ. Hydropathy analysis was employed to analyse the hypothetical protein sequence subsequently translated and to identify an appropriate epitope to generate a specific monoclonal antibody. RESULTS A novel sequence was identified within the 3'-terminal domain of human PRKCZ that, in prostate cancer cell lines and tissues, is expressed during transcription and thereafter translated into protein (designated PKC-ζ(-PrC)) independent of conventional PKC-ζ(-a). The monoclonal antibody detected expression of this 96 kD protein only within malignant prostatic epithelium. INTERPRETATION Transcription and translation of this gene sequence, including previous intronic sequences, generates a novel specific biomarker of human prostate cancer. The presence of catalytic domains characteristic of classic PKC-β and atypical PKC-ι within PKC-ζ(-PrC) provides a potential mechanism for this PRKCZ variant to modulate the malignant prostatic phenotype out-with normal cell-regulatory control.
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Affiliation(s)
- S Yao
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - S J Ireland
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - A Bee
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - C Beesley
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - S S Forootan
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - A Dodson
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - T Dickinson
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - P Gerard
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - L-Y Lian
- School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - J M Risk
- School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - P Smith
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - M I Malki
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - Y Ke
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - C S Cooper
- University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - C Gosden
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
| | - C S Foster
- Division of Pathology, Department of Molecular and Clinical Cancer Medicine, University of Liverpool, 6th Floor, Duncan Building, Daulby Street, Liverpool L69 3GA, UK
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Tan Y, Chen X, Qi X, Li G, Wang J, Bian S, Xu Z, Wang H. Acute lymphoblastic leukemia expressing b3a2 (p210), e1a2 (p190), and variant e1a2 BCR-ABL transcripts: a case report and review of the literature. Acta Haematol 2012; 128:119-23. [PMID: 22760091 DOI: 10.1159/000338261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 03/16/2012] [Indexed: 11/19/2022]
Affiliation(s)
- Yanhong Tan
- Institute of Hematology, Second Hospital of Shanxi Medical University, Taiyuan, PR China
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Intron Retention and TE Exonization Events in ZRANB2. Comp Funct Genomics 2012; 2012:170208. [PMID: 22778693 PMCID: PMC3384923 DOI: 10.1155/2012/170208] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/14/2012] [Accepted: 05/14/2012] [Indexed: 12/17/2022] Open
Abstract
The Zinc finger, RAN-binding domain-containing protein 2 (ZRANB2), contains arginine/serine-rich (RS) domains that mediate its function in the regulation of alternative splicing. The ZRANB2 gene contains 2 LINE elements (L3b, Plat_L3) between the 9th and 10th exons. We identified the exonization event of a LINE element (Plat_L3). Using genomic PCR, RT-PCR amplification, and sequencing of primate DNA and RNA samples, we analyzed the evolutionary features of ZRANB2 transcripts. The results indicated that 2 of the LINE elements were integrated in human and all of the tested primate samples (hominoids: 3 species; Old World monkey: 8 species; New World monkey: 6 species; prosimian: 1 species). Human, rhesus monkey, crab-eating monkey, African-green monkey, and marmoset harbor the exon derived from LINE element (Plat_L3). RT-PCR amplification revealed the long transcripts and their differential expression patterns. Intriguingly, these long transcripts were abundantly expressed in Old World monkey lineages (rhesus, crab-eating, and African-green monkeys) and were expressed via intron retention (IR). Thus, the ZRANB2 gene produces 3 transcript variants in which the Cterminus varies by transposable elements (TEs) exonization and IR mechanisms. Therefore, ZRANB2 is valuable for investigating the evolutionary mechanisms of TE exonization and IR during primate evolution.
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Tse MY, Ashbury JE, Zwingerman N, King WD, Taylor SA, Pang SC. A refined, rapid and reproducible high resolution melt (HRM)-based method suitable for quantification of global LINE-1 repetitive element methylation. BMC Res Notes 2011; 4:565. [PMID: 22204640 PMCID: PMC3284418 DOI: 10.1186/1756-0500-4-565] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 12/28/2011] [Indexed: 12/28/2022] Open
Abstract
Background The methylation of DNA is recognized as a key mechanism in the regulation of genomic stability and evidence for its role in the development of cancer is accumulating. LINE-1 methylation status represents a surrogate measure of genome-wide methylation. Findings Using high resolution melt (HRM) curve analysis technology, we have established an in-tube assay that is linear (r > 0.9986) with a high amplification efficiency (90-105%), capable of discriminating between partcipant samples with small differences in methylation, and suitable for quantifying a wide range of LINE-1 methylation levels (0-100%)--including the biologically relevant range of 50-90% expected in human DNA. We have optimized this procedure to perform using 2 μg of starting DNA and 2 ng of bisulfite-converted DNA for each PCR reaction. Intra- and inter-assay coefficients of variation were 1.44% and 0.49%, respectively, supporting the high reproducibility and precision of this approach. Conclusions In summary, this is a completely linear, quantitative HRM PCR method developed for the measurement of LINE-1 methylation. This cost-efficient, refined and reproducible assay can be performed using minimal amounts of starting DNA. These features make our assay suitable for high throughput analysis of multiple samples from large population-based studies.
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Affiliation(s)
- M Yat Tse
- Department of Anatomy and Cell Biology, Queen's University, Kingston, ON, Canada.
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