1
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Lee DH, Park EG, Kim JM, Shin HJ, Lee YJ, Jeong HS, Roh HY, Kim WR, Ha H, Kim SW, Choi YH, Kim HS. Genomic analyses of intricate interaction of TE-lncRNA overlapping genes with miRNAs in human diseases. Genes Genomics 2024:10.1007/s13258-024-01547-1. [PMID: 39215947 DOI: 10.1007/s13258-024-01547-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Accepted: 07/09/2024] [Indexed: 09/04/2024]
Abstract
BACKGROUND Transposable elements (TEs) are known to be inserted into genome to create transcript isoforms or to generate long non-coding RNA (lncRNA) sequences. The insertion of TEs generates a gene protein sequence within the genome, but also provides a microRNA (miRNA) regulatory region. OBJECTIVE To determine the effect of gene sequence changes caused by TE insertion on miRNA binding and to investigate the formation of an overlapping lncRNA that represses it. METHODS The distribution of overlapping regions between exons and TE regions with lncRNA was examined using the Bedtools. miRNAs that can bind to those overlapping regions were identified through the miRDB web program. For TE-lncRNA overlapping genes, bioinformatic analysis was conducted using DAVID web database. Differential expression analysis was conducted using data from the GEO dataset and TCGA. RESULTS Most TEs were distributed more frequently in untranslated regions than open reading frames. There were 30 annotated TE-lncRNA overlapping genes with same strand that could bind to the same miRNA. As a result of identifying the association between these 30 genes and diseases, TGFB2, FCGR2A, DCTN5, and IFI6 were associated with breast cancer, and HMGCS1, FRMD4A, EDNRB, and SNCA were associated with Alzheimer's disease. Analysis of the GEO and TCGA data showed that the relevant expression of miR-891a and miR-28, which bind to the TE overlapping region of DCTN5 and HMGCS1, decreased. CONCLUSION This study indicates that the interaction between TE-lncRNA overlapping genes and miRNAs can affect disease progression.
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Affiliation(s)
- Du Hyeong Lee
- Department of Integrated Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Eun Gyung Park
- Department of Integrated Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Jung-Min Kim
- Department of Integrated Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Hae Jin Shin
- Department of Integrated Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Yun Ju Lee
- Department of Integrated Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Hyeon-Su Jeong
- Department of Integrated Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Hyun-Young Roh
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan, 46241, Republic of Korea
| | - Woo Ryung Kim
- Department of Integrated Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Hongseok Ha
- Institute of Endemic Disease, Medical Research Center, Seoul National University, Seoul, 03080, Republic of Korea
| | - Sang-Woo Kim
- Department of Integrated Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan, 46241, Republic of Korea
| | - Yung Hyun Choi
- Department of Biochemistry, College of Oriental Medicine, Dong-Eui University, Busan, 47227, Republic of Korea
| | - Heui-Soo Kim
- Institute of Systems Biology, Pusan National University, Busan, 46241, Republic of Korea.
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan, 46241, Republic of Korea.
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2
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Alkailani MI, Gibbings D. The Regulation and Immune Signature of Retrotransposons in Cancer. Cancers (Basel) 2023; 15:4340. [PMID: 37686616 PMCID: PMC10486412 DOI: 10.3390/cancers15174340] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 08/14/2023] [Accepted: 08/18/2023] [Indexed: 09/10/2023] Open
Abstract
Advances in sequencing technologies and the bioinformatic analysis of big data facilitate the study of jumping genes' activity in the human genome in cancer from a broad perspective. Retrotransposons, which move from one genomic site to another by a copy-and-paste mechanism, are regulated by various molecular pathways that may be disrupted during tumorigenesis. Active retrotransposons can stimulate type I IFN responses. Although accumulated evidence suggests that retrotransposons can induce inflammation, the research investigating the exact mechanism of triggering these responses is ongoing. Understanding these mechanisms could improve the therapeutic management of cancer through the use of retrotransposon-induced inflammation as a tool to instigate immune responses to tumors.
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Affiliation(s)
- Maisa I. Alkailani
- College of Health and Life Sciences, Hamad Bin Khalifa University, Qatar Foundation, Doha P.O. Box 34110, Qatar
| | - Derrick Gibbings
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada;
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3
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Zhao P, Peng C, Fang L, Wang Z, Liu GE. Taming transposable elements in livestock and poultry: a review of their roles and applications. Genet Sel Evol 2023; 55:50. [PMID: 37479995 PMCID: PMC10362595 DOI: 10.1186/s12711-023-00821-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 06/30/2023] [Indexed: 07/23/2023] Open
Abstract
Livestock and poultry play a significant role in human nutrition by converting agricultural by-products into high-quality proteins. To meet the growing demand for safe animal protein, genetic improvement of livestock must be done sustainably while minimizing negative environmental impacts. Transposable elements (TE) are important components of livestock and poultry genomes, contributing to their genetic diversity, chromatin states, gene regulatory networks, and complex traits of economic value. However, compared to other species, research on TE in livestock and poultry is still in its early stages. In this review, we analyze 72 studies published in the past 20 years, summarize the TE composition in livestock and poultry genomes, and focus on their potential roles in functional genomics. We also discuss bioinformatic tools and strategies for integrating multi-omics data with TE, and explore future directions, feasibility, and challenges of TE research in livestock and poultry. In addition, we suggest strategies to apply TE in basic biological research and animal breeding. Our goal is to provide a new perspective on the importance of TE in livestock and poultry genomes.
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Affiliation(s)
- Pengju Zhao
- Hainan Institute of Zhejiang University, Hainan Sanya, 572000, China
- College of Animal Sciences, Zhejiang University, Zhejiang, Hangzhou, People's Republic of China
| | - Chen Peng
- Hainan Institute of Zhejiang University, Hainan Sanya, 572000, China
- College of Animal Sciences, Zhejiang University, Zhejiang, Hangzhou, People's Republic of China
| | - Lingzhao Fang
- Center for Quantitative Genetics and Genomics, Aarhus University, 8000, Aarhus, Denmark.
| | - Zhengguang Wang
- Hainan Institute of Zhejiang University, Hainan Sanya, 572000, China.
- College of Animal Sciences, Zhejiang University, Zhejiang, Hangzhou, People's Republic of China.
| | - George E Liu
- Animal Genomics and Improvement Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Beltsville, MD, 20705, USA.
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4
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Berthelier J, Furci L, Asai S, Sadykova M, Shimazaki T, Shirasu K, Saze H. Long-read direct RNA sequencing reveals epigenetic regulation of chimeric gene-transposon transcripts in Arabidopsis thaliana. Nat Commun 2023; 14:3248. [PMID: 37277361 DOI: 10.1038/s41467-023-38954-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 05/21/2023] [Indexed: 06/07/2023] Open
Abstract
Transposable elements (TEs) are accumulated in both intergenic and intragenic regions in plant genomes. Intragenic TEs often act as regulatory elements of associated genes and are also co-transcribed with genes, generating chimeric TE-gene transcripts. Despite the potential impact on mRNA regulation and gene function, the prevalence and transcriptional regulation of TE-gene transcripts are poorly understood. By long-read direct RNA sequencing and a dedicated bioinformatics pipeline, ParasiTE, we investigated the transcription and RNA processing of TE-gene transcripts in Arabidopsis thaliana. We identified a global production of TE-gene transcripts in thousands of A. thaliana gene loci, with TE sequences often being associated with alternative transcription start sites or transcription termination sites. The epigenetic state of intragenic TEs affects RNAPII elongation and usage of alternative poly(A) signals within TE sequences, regulating alternative TE-gene isoform production. Co-transcription and inclusion of TE-derived sequences into gene transcripts impact regulation of RNA stability and environmental responses of some loci. Our study provides insights into TE-gene interactions that contributes to mRNA regulation, transcriptome diversity, and environmental responses in plants.
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Grants
- JP20H02995 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JP22H00364 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JP20H05909 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JP20H05913 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
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Affiliation(s)
- Jérémy Berthelier
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan.
| | - Leonardo Furci
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Shuta Asai
- Center for Sustainable Resource Science, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan
| | - Munissa Sadykova
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Tomoe Shimazaki
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Ken Shirasu
- Center for Sustainable Resource Science, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan
| | - Hidetoshi Saze
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan.
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5
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Spencley AL, Bar S, Swigut T, Flynn RA, Lee CH, Chen LF, Bassik MC, Wysocka J. Co-transcriptional genome surveillance by HUSH is coupled to termination machinery. Mol Cell 2023; 83:1623-1639.e8. [PMID: 37164018 PMCID: PMC10915761 DOI: 10.1016/j.molcel.2023.04.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 01/12/2023] [Accepted: 04/12/2023] [Indexed: 05/12/2023]
Abstract
The HUSH complex recognizes and silences foreign DNA such as viruses, transposons, and transgenes without prior exposure to its targets. Here, we show that endogenous targets of the HUSH complex fall into two distinct classes based on the presence or absence of H3K9me3. These classes are further distinguished by their transposon content and differential response to the loss of HUSH. A de novo genomic rearrangement at the Sox2 locus induces a switch from H3K9me3-independent to H3K9me3-associated HUSH targeting, resulting in silencing. We further demonstrate that HUSH interacts with the termination factor WDR82 and-via its component MPP8-with nascent RNA. HUSH accumulates at sites of high RNAPII occupancy including long exons and transcription termination sites in a manner dependent on WDR82 and CPSF. Together, our results uncover the functional diversity of HUSH targets and show that this vertebrate-specific complex exploits evolutionarily ancient transcription termination machinery for co-transcriptional chromatin targeting and genome surveillance.
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Affiliation(s)
- Andrew L Spencley
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, CA, USA
| | - Shiran Bar
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Tomek Swigut
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Ryan A Flynn
- Stem Cell Program, Boston Children's Hospital, Boston, MA, USA; Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA
| | - Cameron H Lee
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Liang-Fu Chen
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Michael C Bassik
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Joanna Wysocka
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA; Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA; Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA.
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6
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Kim WR, Park EG, Lee YJ, Bae WH, Lee DH, Kim HS. Integration of TE Induces Cancer Specific Alternative Splicing Events. Int J Mol Sci 2022; 23:10918. [PMID: 36142830 PMCID: PMC9502224 DOI: 10.3390/ijms231810918] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/13/2022] [Accepted: 09/13/2022] [Indexed: 11/16/2022] Open
Abstract
Alternative splicing of messenger RNA (mRNA) precursors contributes to genetic diversity by generating structurally and functionally distinct transcripts. In a disease state, alternative splicing promotes incidence and development of several cancer types through regulation of cancer-related biological processes. Transposable elements (TEs), having the genetic ability to jump to other regions of the genome, can bring about alternative splicing events in cancer. TEs can integrate into the genome, mostly in the intronic regions, and induce cancer-specific alternative splicing by adjusting various mechanisms, such as exonization, providing splicing donor/acceptor sites, alternative regulatory sequences or stop codons, and driving exon disruption or epigenetic regulation. Moreover, TEs can produce microRNAs (miRNAs) that control the proportion of transcripts by repressing translation or stimulating the degradation of transcripts at the post-transcriptional level. Notably, TE insertion creates a cancer-friendly environment by controlling the overall process of gene expression before and after transcription in cancer cells. This review emphasizes the correlative interaction between alternative splicing by TE integration and cancer-associated biological processes, suggesting a macroscopic mechanism controlling alternative splicing by TE insertion in cancer.
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Affiliation(s)
- Woo Ryung Kim
- Department of Integrated Biological Sciences, Pusan National University, Busan 46241, Korea
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
| | - Eun Gyung Park
- Department of Integrated Biological Sciences, Pusan National University, Busan 46241, Korea
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
| | - Yun Ju Lee
- Department of Integrated Biological Sciences, Pusan National University, Busan 46241, Korea
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
| | - Woo Hyeon Bae
- Department of Integrated Biological Sciences, Pusan National University, Busan 46241, Korea
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
| | - Du Hyeong Lee
- Department of Integrated Biological Sciences, Pusan National University, Busan 46241, Korea
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
| | - Heui-Soo Kim
- Institute of Systems Biology, Pusan National University, Busan 46241, Korea
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 46241, Korea
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7
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Pinto A, Cunha C, Chaves R, Butchbach MER, Adega F. Comprehensive In Silico Analysis of Retrotransposon Insertions within the Survival Motor Neuron Genes Involved in Spinal Muscular Atrophy. BIOLOGY 2022; 11:824. [PMID: 35741345 PMCID: PMC9219815 DOI: 10.3390/biology11060824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 05/19/2022] [Accepted: 05/25/2022] [Indexed: 11/16/2022]
Abstract
Transposable elements (TEs) are interspersed repetitive and mobile DNA sequences within the genome. Better tools for evaluating TE-derived sequences have provided insights into the contribution of TEs to human development and disease. Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disease that is caused by deletions or mutations in the Survival Motor Neuron 1 (SMN1) gene but retention of its nearly perfect orthologue SMN2. Both genes are highly enriched in TEs. To establish a link between TEs and SMA, we conducted a comprehensive, in silico analysis of TE insertions within the SMN1/2 loci of SMA, carrier and healthy genomes. We found an Alu insertion in the promoter region and one L1 element in the 3'UTR that may play an important role in alternative promoter as well as in alternative transcriptional termination. Additionally, several intronic Alu repeats may influence alternative splicing via RNA circularization and causes the presence of new alternative exons. These Alu repeats present throughout the genes are also prone to recombination events that could lead to SMN1 exons deletions and, ultimately, SMA. TE characterization of the SMA genomic region could provide for a better understanding of the implications of TEs on human disease and genomic evolution.
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Affiliation(s)
- Albano Pinto
- Laboratory of Cytogenomics and Animal Genomics (CAG), Department of Genetics and Biotechnology (DGB), University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal; (A.P.); (C.C.); (R.C.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, 1749-016 Lisbon, Portugal
| | - Catarina Cunha
- Laboratory of Cytogenomics and Animal Genomics (CAG), Department of Genetics and Biotechnology (DGB), University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal; (A.P.); (C.C.); (R.C.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, 1749-016 Lisbon, Portugal
| | - Raquel Chaves
- Laboratory of Cytogenomics and Animal Genomics (CAG), Department of Genetics and Biotechnology (DGB), University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal; (A.P.); (C.C.); (R.C.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, 1749-016 Lisbon, Portugal
| | - Matthew E. R. Butchbach
- Division of Neurology, Nemours Children’s Hospital Delaware, Wilmington, DE 19803, USA;
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
- Department of Pediatrics, Sidney Kimmel College of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Filomena Adega
- Laboratory of Cytogenomics and Animal Genomics (CAG), Department of Genetics and Biotechnology (DGB), University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal; (A.P.); (C.C.); (R.C.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, 1749-016 Lisbon, Portugal
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8
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Chesnokova E, Beletskiy A, Kolosov P. The Role of Transposable Elements of the Human Genome in Neuronal Function and Pathology. Int J Mol Sci 2022; 23:5847. [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] [MESH Headings] [Grants] [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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Affiliation(s)
- Ekaterina Chesnokova
- Laboratory of Cellular Neurobiology of Learning, Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences, 117485 Moscow, Russia; (A.B.); (P.K.)
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9
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Guvenek A, Shin J, De Filippis L, Zheng D, Wang W, Pang ZP, Tian B. Neuronal Cells Display Distinct Stability Controls of Alternative Polyadenylation mRNA Isoforms, Long Non-Coding RNAs, and Mitochondrial RNAs. Front Genet 2022; 13:840369. [PMID: 35664307 PMCID: PMC9159357 DOI: 10.3389/fgene.2022.840369] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 02/28/2022] [Indexed: 11/25/2022] Open
Abstract
RNA stability plays an important role in gene expression. Here, using 3' end sequencing of newly made and pre-existing poly(A)+ RNAs, we compare transcript stability in multiple human cell lines, including HEK293T, HepG2, and SH-SY5Y. We show that while mRNA stability is generally conserved across the cell lines, specific transcripts having a high GC content and possibly more stable secondary RNA structures are relatively more stable in SH-SY5Y cells compared to the other 2 cell lines. These features also differentiate stability levels of alternative polyadenylation (APA) 3'UTR isoforms in a cell type-specific manner. Using differentiation of a neural stem cell line as a model, we show that mRNA stability difference could contribute to gene expression changes in neurogenesis and confirm the neuronal identity of SH-SY5Y cells at both gene expression and APA levels. In addition, compared to transcripts using 3'-most exon cleavage/polyadenylation sites (PASs), those using intronic PASs are generally less stable, especially when the PAS-containing intron is large and has a strong 5' splice site, suggesting that intronic polyadenylation mostly plays a negative role in gene expression. Interestingly, the differential mRNA stability among APA isoforms appears to buffer PAS choice in these cell lines. Moreover, we found that several other poly(A)+ RNA species, including promoter-associated long noncoding RNAs and transcripts encoded by the mitochondrial genome, are more stable in SH-SY5Y cells than the other 2 cell lines, further highlighting distinct RNA metabolism in neuronal cells. Together, our results indicate that distinct RNA stability control in neuronal cells may contribute to the gene expression and APA programs that define their cell identity.
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Affiliation(s)
- Aysegul Guvenek
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, United States
- Rutgers School of Graduate Studies, Newark, NJ, United States
| | - Jihae Shin
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Lidia De Filippis
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Dinghai Zheng
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Wei Wang
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Zhiping P. Pang
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Bin Tian
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, United States
- Program in Gene Expression and Regulation, Center for Systems and Computational Biology, The Wistar Institute, Philadelphia, PA, United States
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10
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Zhang X, Zhu YN, Chen B, Kang L. A Gypsy element contributes to the nuclear retention and transcriptional regulation of the resident lncRNA in locusts. RNA Biol 2022; 19:206-220. [PMID: 35067197 PMCID: PMC8786324 DOI: 10.1080/15476286.2021.2024032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The majority of long noncoding RNAs (lncRNAs) contain transposable elements (TEs). PAHAL, a nuclear-retained lncRNA that is inserted by a Gypsy retrotransposon, has been shown to be a vital regulator of phenylalanine hydroxylase (PAH) gene expression that controls dopamine biosynthesis and behavioural aggregation in the migratory locust. However, the role of the Gypsy retrotransposon in the transcriptional regulation of PAHAL remains unknown. Here, we identified a Gypsy retrotransposon (named Gypsy element) as an inverted long terminal repeat located in the 3′ end of PAHAL, representing a feature shared by many other lncRNAs in the locust genome. The embedded Gypsy element contains a RNA nuclear localization signal motif, which promotes the stable accumulation of PAHAL in the nucleus. The Gypsy element also provides high-affinity SRSF2 binding sites for PAHAL that induce the recruitment of SRSF2, resulting in the PAHAL-mediated transcriptional activation of PAH. Thus, our data demonstrate that TEs provide discrete functional domains for lncRNA organization and highlight the contribution of TEs to the regulatory significance of lncRNAs.
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Affiliation(s)
- Xia Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Ya Nan Zhu
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Bing Chen
- School of Life Sciences, Hebei University, Baoding, China
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China.,School of Life Sciences, Hebei University, Baoding, China.,Beijing Institute of Life Sciences, Chinese Academy of Sciences, Beijing, China
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11
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Dynamic Variations of 3'UTR Length Reprogram the mRNA Regulatory Landscape. Biomedicines 2021; 9:biomedicines9111560. [PMID: 34829789 PMCID: PMC8615635 DOI: 10.3390/biomedicines9111560] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/10/2021] [Accepted: 10/15/2021] [Indexed: 12/16/2022] Open
Abstract
This paper concerns 3′-untranslated regions (3′UTRs) of mRNAs, which are non-coding regulatory platforms that control stability, fate and the correct spatiotemporal translation of mRNAs. Many mRNAs have polymorphic 3′UTR regions. Controlling 3′UTR length and sequence facilitates the regulation of the accessibility of functional effectors (RNA binding proteins, miRNAs or other ncRNAs) to 3′UTR functional boxes and motifs and the establishment of different regulatory landscapes for mRNA function. In this context, shortening of 3′UTRs would loosen miRNA or protein-based mechanisms of mRNA degradation, while 3′UTR lengthening would strengthen accessibility to these effectors. Alterations in the mechanisms regulating 3′UTR length would result in widespread deregulation of gene expression that could eventually lead to diseases likely linked to the loss (or acquisition) of specific miRNA binding sites. Here, we will review the mechanisms that control 3′UTR length dynamics and their alterations in human disorders. We will discuss, from a mechanistic point of view centered on the molecular machineries involved, the generation of 3′UTR variability by the use of alternative polyadenylation and cleavage sites, of mutually exclusive terminal alternative exons (exon skipping) as well as by the process of exonization of Alu cassettes to generate new 3′UTRs with differential functional features.
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12
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Blake D, Lynch KW. The three as: Alternative splicing, alternative polyadenylation and their impact on apoptosis in immune function. Immunol Rev 2021; 304:30-50. [PMID: 34368964 DOI: 10.1111/imr.13018] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/19/2021] [Accepted: 07/28/2021] [Indexed: 12/13/2022]
Abstract
The latest advances in next-generation sequencing studies and transcriptomic profiling over the past decade have highlighted a surprising frequency of genes regulated by RNA processing mechanisms in the immune system. In particular, two control steps in mRNA maturation, namely alternative splicing and alternative polyadenylation, are now recognized to occur in the vast majority of human genes. Both have the potential to alter the identity of the encoded protein, as well as control protein abundance or even protein localization or association with other factors. In this review, we will provide a summary of the general mechanisms by which alternative splicing (AS) and alternative polyadenylation (APA) occur, their regulation within cells of the immune system, and their impact on immunobiology. In particular, we will focus on how control of apoptosis by AS and APA is used to tune cell fate during an immune response.
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Affiliation(s)
- Davia Blake
- Immunology Graduate Group and the Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kristen W Lynch
- Immunology Graduate Group and the Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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13
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Mangiavacchi A, Liu P, Della Valle F, Orlando V. New insights into the functional role of retrotransposon dynamics in mammalian somatic cells. Cell Mol Life Sci 2021; 78:5245-5256. [PMID: 33990851 PMCID: PMC8257530 DOI: 10.1007/s00018-021-03851-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 03/31/2021] [Accepted: 05/04/2021] [Indexed: 12/18/2022]
Abstract
Retrotransposons are genetic elements present across all eukaryotic genomes. While their role in evolution is considered as a potentially beneficial natural source of genetic variation, their activity is classically considered detrimental due to their potentially harmful effects on genome stability. However, studies are increasingly shedding light on the regulatory function and beneficial role of somatic retroelement reactivation in non-pathological contexts. Here, we review recent findings unveiling the regulatory potential of retrotransposons, including their role in noncoding RNA transcription, as modulators of mammalian transcriptional and epigenome landscapes. We also discuss technical challenges in deciphering the multifaceted activity of retrotransposable elements, highlighting an unforeseen central role of this neglected portion of the genome both in early development and in adult life.
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Affiliation(s)
- Arianna Mangiavacchi
- Biological Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Peng Liu
- Biological Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Francesco Della Valle
- Biological Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Valerio Orlando
- Biological Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
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14
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Han G, Zhang N, Jiang H, Meng X, Qian K, Zheng Y, Xu J, Wang J. Diversity of short interspersed nuclear elements (SINEs) in lepidopteran insects and evidence of horizontal SINE transfer between baculovirus and lepidopteran hosts. BMC Genomics 2021; 22:226. [PMID: 33789582 PMCID: PMC8010984 DOI: 10.1186/s12864-021-07543-z] [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: 08/03/2020] [Accepted: 03/22/2021] [Indexed: 11/16/2022] Open
Abstract
Background Short interspersed nuclear elements (SINEs) belong to non-long terminal repeat (non-LTR) retrotransposons, which can mobilize dependent on the help of counterpart long interspersed nuclear elements (LINEs). Although 234 SINEs have been identified so far, only 23 are from insect species (SINEbase: http://sines.eimb.ru/). Results Here, five SINEs were identified from the genome of Plutella xylostella, among which PxSE1, PxSE2 and PxSE3 were tRNA-derived SINEs, PxSE4 and PxSE5 were 5S RNA-derived SINEs. A total of 18 related SINEs were further identified in 13 lepidopteran insects and a baculovirus. The 3′-tail of PxSE5 shares highly identity with that of LINE retrotransposon, PxLINE1. The analysis of relative age distribution profiles revealed that PxSE1 is a relatively young retrotransposon in the genome of P. xylostella and was generated by recent explosive amplification. Integration pattern analysis showed that SINEs in P. xylostella prefer to insert into or accumulate in introns and regions 5 kb downstream of genes. In particular, the PxSE1-like element, SlNPVSE1, in Spodoptera litura nucleopolyhedrovirus II genome is highly identical to SfSE1 in Spodoptera frugiperda, SlittSE1 in Spodoptera littoralis, and SlituSE1 in Spodoptera litura, suggesting the occurrence of horizontal transfer. Conclusions Lepidopteran insect genomes harbor a diversity of SINEs. The retrotransposition activity and copy number of these SINEs varies considerably between host lineages and SINE lineages. Host-parasite interactions facilitate the horizontal transfer of SINE between baculovirus and its lepidopteran hosts. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07543-z.
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Affiliation(s)
- Guangjie Han
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, 225009, China.,Jiangsu Lixiahe District Institute of Agricultural Sciences, Yangzhou, 225008, China
| | - Nan Zhang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, 225009, China
| | - Heng Jiang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, 225009, China
| | - Xiangkun Meng
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, 225009, China
| | - Kun Qian
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, 225009, China
| | - Yang Zheng
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, 225009, China
| | - Jian Xu
- Jiangsu Lixiahe District Institute of Agricultural Sciences, Yangzhou, 225008, China.
| | - Jianjun Wang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, 225009, China. .,Joint International Research Laboratory of Agriculture andAgri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou, 225009, China.
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15
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Evans TA, Erwin JA. Retroelement-derived RNA and its role in the brain. Semin Cell Dev Biol 2020; 114:68-80. [PMID: 33229216 DOI: 10.1016/j.semcdb.2020.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 10/20/2020] [Accepted: 11/04/2020] [Indexed: 12/17/2022]
Abstract
Comprising ~40% of the human genome, retroelements are mobile genetic elements which are transcribed into RNA, then reverse-transcribed into DNA and inserted into a new site in the genome. Retroelements are referred to as "genetic parasites", residing among host genes and relying on host machinery for transcription and evolutionary propagation. The healthy brain has the highest expression of retroelement-derived sequences compared to other somatic tissue, which leads to the question: how does retroelement-derived RNA influence human traits and cellular states? While the functional importance of upregulating retroelement expression in the brain is an active area of research, RNA species derived from retroelements influence both self- and host gene expression by contributing to chromatin remodeling, alternative splicing, somatic mosaicism and translational repression. Here, we review the emerging evidence that the functional importance of RNA derived from retroelements is multifaceted. Retroelements can influence organismal states through the seeding of epigenetic states in chromatin, the production of structured RNA and even catalytically active ribozymes, the generation of cytoplasmic ssDNA and RNA/DNA hybrids, the production of viral-like proteins, and the generation of somatic mutations. Comparative sequencing suggests that retroelements can contribute to intraspecies variation through these mechanisms to alter transcript identity and abundance. In humans, an increasing number of neurodevelopmental and neurodegenerative conditions are associated with dysregulated retroelements, including Aicardi-Goutieres syndrome (AGS), Rett syndrome (RTT), Amyotrophic Lateral Sclerosis (ALS), Alzheimer's disease (AD), multiple sclerosis (MS), schizophrenia (SZ), and aging. Taken together, these concepts suggest a larger functional role for RNA derived from retroelements. This review aims to define retroelement-derived RNA, discuss how it impacts the mammalian genome, as well as summarize data supporting phenotypic consequences of this unique RNA subset in the brain.
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Affiliation(s)
- Taylor A Evans
- Lieber Institute for Brain Development, Baltimore, MD, USA; Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Jennifer Ann Erwin
- Lieber Institute for Brain Development, Baltimore, MD, USA; Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD, USA; Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, USA.
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16
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Bhattacharya A, Jha V, Singhal K, Fatima M, Singh D, Chaturvedi G, Dholakia D, Kutum R, Pandey R, Bakken TE, Seth P, Pillai B, Mukerji M. Multiple Alu Exonization in 3'UTR of a Primate-Specific Isoform of CYP20A1 Creates a Potential miRNA Sponge. Genome Biol Evol 2020; 13:5958120. [PMID: 33434274 PMCID: PMC7802813 DOI: 10.1093/gbe/evaa233] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2020] [Indexed: 12/13/2022] Open
Abstract
Alu repeats contribute to phylogenetic novelties in conserved regulatory networks in primates. Our study highlights how exonized Alus could nucleate large-scale mRNA-miRNA interactions. Using a functional genomics approach, we characterize a transcript isoform of an orphan gene, CYP20A1 (CYP20A1_Alu-LT) that has exonization of 23 Alus in its 3'UTR. CYP20A1_Alu-LT, confirmed by 3'RACE, is an outlier in length (9 kb 3'UTR) and widely expressed. Using publically available data sets, we demonstrate its expression in higher primates and presence in single nucleus RNA-seq of 15,928 human cortical neurons. miRanda predicts ∼4,700 miRNA recognition elements (MREs) for ∼1,000 miRNAs, primarily originated within these 3'UTR-Alus. CYP20A1_Alu-LT could be a potential multi-miRNA sponge as it harbors ≥10 MREs for 140 miRNAs and has cytosolic localization. We further tested whether expression of CYP20A1_Alu-LT correlates with mRNAs harboring similar MRE targets. RNA-seq with conjoint miRNA-seq analysis was done in primary human neurons where we observed CYP20A1_Alu-LT to be downregulated during heat shock response and upregulated in HIV1-Tat treatment. In total, 380 genes were positively correlated with its expression (significantly downregulated in heat shock and upregulated in Tat) and they harbored MREs for nine expressed miRNAs which were also enriched in CYP20A1_Alu-LT. MREs were significantly enriched in these 380 genes compared with random sets of differentially expressed genes (P = 8.134e-12). Gene ontology suggested involvement of these genes in neuronal development and hemostasis pathways thus proposing a novel component of Alu-miRNA-mediated transcriptional modulation that could govern specific physiological outcomes in higher primates.
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Affiliation(s)
- Aniket Bhattacharya
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Vineet Jha
- Persistent LABS, Persistent Systems Ltd., Pune, Maharashtra, India
| | - Khushboo Singhal
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Mahar Fatima
- Department of Molecular and Cellular Neuroscience, Neurovirology Section, National Brain Research Centre (NBRC), Manesar, Haryana, India
| | - Dayanidhi Singh
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Gaura Chaturvedi
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Dhwani Dholakia
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Rintu Kutum
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Rajesh Pandey
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India
| | | | - Pankaj Seth
- Department of Molecular and Cellular Neuroscience, Neurovirology Section, National Brain Research Centre (NBRC), Manesar, Haryana, India
| | - Beena Pillai
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Mitali Mukerji
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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17
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Zheng D, Cho H, Wang W, Rambout X, Tian B, Maquat LE. 3'READS + RIP defines differential Staufen1 binding to alternative 3'UTR isoforms and reveals structures and sequence motifs influencing binding and polysome association. RNA (NEW YORK, N.Y.) 2020; 26:1621-1636. [PMID: 32796083 PMCID: PMC7566578 DOI: 10.1261/rna.076133.120] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/15/2020] [Indexed: 06/11/2023]
Abstract
Staufen1 (STAU1) is an RNA-binding protein (RBP) that interacts with double-stranded RNA structures and has been implicated in regulating different aspects of mRNA metabolism. Previous studies have indicated that STAU1 interacts extensively with RNA structures in coding regions (CDSs) and 3'-untranslated regions (3'UTRs). In particular, duplex structures formed within 3'UTRs by inverted-repeat Alu elements (IRAlus) interact with STAU1 through its double-stranded RNA-binding domains (dsRBDs). Using 3' region extraction and deep sequencing coupled to ribonucleoprotein immunoprecipitation (3'READS + RIP), together with reanalyzing previous STAU1 binding and RNA structure data, we delineate STAU1 interactions transcriptome-wide, including binding differences between alternative polyadenylation (APA) isoforms. Consistent with previous reports, RNA structures are dominant features for STAU1 binding to CDSs and 3'UTRs. Overall, relative to short 3'UTR counterparts, longer 3'UTR isoforms of genes have stronger STAU1 binding, most likely due to a higher frequency of RNA structures, including specific IRAlus sequences. Nevertheless, a sizable fraction of genes express transcripts showing the opposite trend, attributable to AU-rich sequences in their alternative 3'UTRs that may recruit antagonistic RBPs and/or destabilize RNA structures. Using STAU1-knockout cells, we show that strong STAU1 binding to mRNA 3'UTRs generally enhances polysome association. However, IRAlus generally have little impact on STAU1-mediated polysome association despite having strong interactions with the protein. Taken together, our work reveals complex interactions of STAU1 with its cognate RNA substrates. Our data also shed light on distinct post-transcriptional fates for the widespread APA isoforms in mammalian cells.
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Affiliation(s)
- Dinghai Zheng
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
| | - Hana Cho
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
- Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
| | - Wei Wang
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
| | - Xavier Rambout
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
- Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
| | - Bin Tian
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
- Program in Gene Expression and Regulation, and Center for Systems and Computational Biology, Wistar Institute, Philadelphia, Pennsylvania 19104, USA
| | - Lynne E Maquat
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
- Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
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18
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Nguyen TM, Alchalabi S, Oluwatoyosi A, Ropri AS, Herschkowitz JI, Rosen JM. New twists on long noncoding RNAs: from mobile elements to motile cancer cells. RNA Biol 2020; 17:1535-1549. [PMID: 32522127 DOI: 10.1080/15476286.2020.1760535] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The purpose of this review is to highlight several areas of lncRNA biology and cancer that we hope will provide some new insights for future research. These include the relationship of lncRNAs and the epithelial to mesenchymal transition (EMT) with a focus on transcriptional and alternative splicing mechanisms and mRNA stability through miRNAs. In addition, we highlight the potential role of enhancer e-lncRNAs, the importance of transposable elements in lncRNA biology, and finally the emerging area of using antisense oligonucleotides (ASOs) and small molecules to target lncRNAs and their therapeutic implications.
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Affiliation(s)
- Tuan M Nguyen
- Harvard Medical School Initiative for RNA Medicine, Harvard Medical School , Boston, MA, USA.,Cancer Research Institute, Beth Israel Deaconess Medical Center, Department of Medicine and Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School , Boston, MA, USA
| | - Sumayya Alchalabi
- Department of Biomedical Sciences, Cancer Research Center, University at Albany, SUNY , Rensselaer, NY, USA
| | - Adewunmi Oluwatoyosi
- Department of Molecular & Cellular Biology, Baylor College of Medicine , Houston, TX, USA
| | - Ali S Ropri
- Department of Biomedical Sciences, Cancer Research Center, University at Albany, SUNY , Rensselaer, NY, USA
| | - Jason I Herschkowitz
- Department of Biomedical Sciences, Cancer Research Center, University at Albany, SUNY , Rensselaer, NY, USA
| | - Jeffrey M Rosen
- Department of Molecular & Cellular Biology, Baylor College of Medicine , Houston, TX, USA
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19
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Ueberham U, Arendt T. Genomic Indexing by Somatic Gene Recombination of mRNA/ncRNA - Does It Play a Role in Genomic Mosaicism, Memory Formation, and Alzheimer's Disease? Front Genet 2020; 11:370. [PMID: 32411177 PMCID: PMC7200996 DOI: 10.3389/fgene.2020.00370] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 03/25/2020] [Indexed: 12/26/2022] Open
Abstract
Recent evidence indicates that genomic individuality of neurons, characterized by DNA-content variation, is a common if not universal phenomenon in the human brain that occurs naturally but can also show aberrancies that have been linked to the pathomechanism of Alzheimer’s disease and related neurodegenerative disorders. Etiologically, this genomic mosaic has been suggested to arise from defects of cell cycle regulation that may occur either during brain development or in the mature brain after terminal differentiation of neurons. Here, we aim to draw attention towards another mechanism that can give rise to genomic individuality of neurons, with far-reaching consequences. This mechanism has its origin in the transcriptome rather than in replication defects of the genome, i.e., somatic gene recombination of RNA. We continue to develop the concept that somatic gene recombination of RNA provides a physiological process that, through integration of intronless mRNA/ncRNA into the genome, allows a particular functional state at the level of the individual neuron to be indexed. By insertion of defined RNAs in a somatic recombination process, the presence of specific mRNA transcripts within a definite temporal context can be “frozen” and can serve as an index that can be recalled at any later point in time. This allows information related to a specific neuronal state of differentiation and/or activity relevant to a memory trace to be fixed. We suggest that this process is used throughout the lifetime of each neuron and might have both advantageous and deleterious consequences.
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Affiliation(s)
- Uwe Ueberham
- Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
| | - Thomas Arendt
- Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
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20
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Li Y, Schaefke B, Zou X, Zhang M, Heyd F, Sun W, Zhang B, Li G, Liang W, He Y, Zhou J, Li Y, Fang L, Hu Y, Chen W. Pan-tissue analysis of allelic alternative polyadenylation suggests widespread functional regulation. Mol Syst Biol 2020; 16:e9367. [PMID: 32311237 PMCID: PMC7170663 DOI: 10.15252/msb.20199367] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/29/2020] [Accepted: 03/11/2020] [Indexed: 12/14/2022] Open
Abstract
Alternative polyadenylation (APA) is a major layer of gene regulation. However, it has recently been argued that most APA represents molecular noise. To clarify their functional relevance and evolution, we quantified allele-specific APA patterns in multiple tissues from an F1 hybrid mouse. We found a clearly negative correlation between gene expression and APA diversity for the 2,866 genes (24.9%) with a dominant polyadenylation site (PAS) usage above or equal to 90%, suggesting that their other PASs represent molecular errors. Among the remaining genes with multiple PASs, 3,971 genes (34.5%) express two or more isoforms with potentially functional importance. Interestingly, the genes with potentially functional minor PASs specific to neuronal tissues often express two APA isoforms with distinct subcellular localizations. Furthermore, our analysis of cis-APA divergence shows its pattern across tissues is distinct from that of gene expression. Finally, we demonstrate that the relative usage of alternative PASs is not only affected by their cis-regulatory elements, but also by potential coupling between transcriptional and APA regulation as well as competition kinetics between alternative sites.
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Affiliation(s)
- Yisheng Li
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
- Laboratory of RNA BiochemistryInstitute of Chemistry and BiochemistryFreie Universität BerlinBerlinGermany
| | - Bernhard Schaefke
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
- Academy for Advanced Interdisciplinary StudiesSouthern University of Science and TechnologyShenzhenChina
| | - Xudong Zou
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
| | - Min Zhang
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
| | - Florian Heyd
- Laboratory of RNA BiochemistryInstitute of Chemistry and BiochemistryFreie Universität BerlinBerlinGermany
| | - Wei Sun
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
- Present address:
Department of Pharmaceutical Chemistry and the Cardiovascular Research InstituteUniversity of California San FranciscoSan FranciscoCAUSA
| | - Bin Zhang
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
- Present address:
Cancer Science Institute of SingaporeNational University of SingaporeSingapore CitySingapore
| | - Guipeng Li
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
- Academy for Advanced Interdisciplinary StudiesSouthern University of Science and TechnologyShenzhenChina
| | - Weizheng Liang
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
| | - Yuhao He
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
| | - Juexiao Zhou
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
| | - Yunfei Li
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
| | - Liang Fang
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
- Academy for Advanced Interdisciplinary StudiesSouthern University of Science and TechnologyShenzhenChina
| | - Yuhui Hu
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
| | - Wei Chen
- Department of BiologySouthern University of Science and TechnologyShenzhenChina
- Academy for Advanced Interdisciplinary StudiesSouthern University of Science and TechnologyShenzhenChina
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21
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Kainov YA, Makeyev EV. A transcriptome-wide antitermination mechanism sustaining identity of embryonic stem cells. Nat Commun 2020; 11:361. [PMID: 31953406 PMCID: PMC6969169 DOI: 10.1038/s41467-019-14204-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 12/11/2019] [Indexed: 11/29/2022] Open
Abstract
Eukaryotic gene expression relies on extensive crosstalk between transcription and RNA processing. Changes in this composite regulation network may provide an important means for shaping cell type-specific transcriptomes. Here we show that the RNA-associated protein Srrt/Ars2 sustains embryonic stem cell (ESC) identity by preventing premature termination of numerous transcripts at cryptic cleavage/polyadenylation sites in first introns. Srrt interacts with the nuclear cap-binding complex and facilitates recruitment of the spliceosome component U1 snRNP to cognate intronic positions. At least in some cases, U1 recruited in this manner inhibits downstream cleavage/polyadenylation events through a splicing-independent mechanism called telescripting. We further provide evidence that the naturally high expression of Srrt in ESCs offsets deleterious effects of retrotransposable sequences accumulating in its targets. Our work identifies Srrt as a molecular guardian of the pluripotent cell state. Besides its role in splicing, U1 snRNP can suppress pre-mRNA cleavage and polyadenylation. The authors show that the nuclear cap-binding complex component Srrt/Ars2 maintains embryonic stem cell identity by promoting U1 recruitment to first introns and preventing premature termination of multiple transcripts.
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Affiliation(s)
- Yaroslav A Kainov
- Centre for Developmental Neurobiology, King's College London, London, SE1 1UL, UK
| | - Eugene V Makeyev
- Centre for Developmental Neurobiology, King's College London, London, SE1 1UL, UK.
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22
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Nishihara H. Transposable elements as genetic accelerators of evolution: contribution to genome size, gene regulatory network rewiring and morphological innovation. Genes Genet Syst 2020; 94:269-281. [PMID: 31932541 DOI: 10.1266/ggs.19-00029] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In the current era, as a growing number of genome sequence assemblies have been reported in animals, an in-depth analysis of transposable elements (TEs) is one of the most fundamental and essential studies for evolutionary genomics. Although TEs have, in general, been regarded as non-functional junk/selfish DNA, parasitic elements or harmful mutagens, studies have revealed that TEs have had a substantial and sometimes beneficial impact on host genomes in several ways. First, TEs are themselves diverse and thus provide lineage-specific characteristics to the genomes. Second, because TEs constitute a substantial fraction of animal genomes, they are a major contributing factor to evolutionary changes in genome size and composition. Third, host organisms have co-opted many repetitive sequences as genes, cis-regulatory elements and chromatin domain boundaries, which alter gene regulatory networks and in addition are partly involved in morphological evolution, as has been well documented in mammals. Here, I review the impact of TEs on various aspects of the genome, such as genome size and diversity in animals, as well as the evolution of gene networks and genome architecture in mammals. Given that a number of TE families probably remain to be discovered in many non-model organisms, unknown TEs may have contributed to gene networks in a much wider variety of animals than considered previously.
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Genome-Wide Profiling of Polyadenylation Events in Maize Using High-Throughput Transcriptomic Sequences. G3-GENES GENOMES GENETICS 2019; 9:2749-2760. [PMID: 31239292 PMCID: PMC6686930 DOI: 10.1534/g3.119.400196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Polyadenylation is an essential post-transcriptional modification of eukaryotic transcripts that plays critical role in transcript stability, localization, transport, and translational efficiency. About 70% genes in plants contain alternative polyadenylation (APA) sites. Despite availability of vast amount of sequencing data, to date, a comprehensive map of the polyadenylation events in maize is not available. Here, 9.48 billion RNA-Seq reads were analyzed to characterize 95,345 Poly(A) Clusters (PAC) in 23,705 (51%) maize genes. Of these, 76% were APA genes. However, most APA genes (55%) expressed a dominant PAC rather than favoring multiple PACs equally. The lincRNA genes with PACs were significantly longer in length than the genes without any PAC and about 48% genes had APA sites. Heterogeneity was observed in 52% of the PACs supporting the imprecise nature of the polyadenylation process. Genomic distribution revealed that the majority of the PACs (78%) were located in the genic regions. Unlike previous studies, large number of PACs were observed in the intergenic (n = 21,264), 5′-UTR (735), CDS (2,542), and the intronic regions (12,841). The CDS and introns with PACs were longer in length than without PACs, whereas intergenic PACs were more often associated with transcripts that lacked annotated 3′-UTRs. Nucleotide composition around PACs demonstrated AT-richness and the common upstream motif was AAUAAA, which is consistent with other plants. According to this study, only 2,830 genes still maintained the use of AAUAAA motif. This large-scale data provides useful insights about the gene expression regulation and could be utilized as evidence to validate the annotation of transcript ends.
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Wang R, Nambiar R, Zheng D, Tian B. PolyA_DB 3 catalogs cleavage and polyadenylation sites identified by deep sequencing in multiple genomes. Nucleic Acids Res 2019; 46:D315-D319. [PMID: 29069441 PMCID: PMC5753232 DOI: 10.1093/nar/gkx1000] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 10/12/2017] [Indexed: 12/11/2022] Open
Abstract
PolyA_DB is a database cataloging cleavage and polyadenylation sites (PASs) in several genomes. Previous versions were based mainly on expressed sequence tags (ESTs), which had a limited amount and could lead to inaccurate PAS identification due to the presence of internal A-rich sequences in transcripts. Here, we present an updated version of the database based solely on deep sequencing data. First, PASs are mapped by the 3′ region extraction and deep sequencing (3′READS) method, ensuring unequivocal PAS identification. Second, a large volume of data based on diverse biological samples increases PAS coverage by 3.5-fold over the EST-based version and provides PAS usage information. Third, strand-specific RNA-seq data are used to extend annotated 3′ ends of genes to obtain more thorough annotations of alternative polyadenylation (APA) sites. Fourth, conservation information of PAS across mammals sheds light on significance of APA sites. The database (URL: http://www.polya-db.org/v3) currently holds PASs in human, mouse, rat and chicken, and has links to the UCSC genome browser for further visualization and for integration with other genomic data.
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Affiliation(s)
- Ruijia Wang
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School and Rutgers Cancer Institute of New Jersey, Newark, NJ 07103, USA
| | - Ram Nambiar
- Department of Computer Science, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Dinghai Zheng
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School and Rutgers Cancer Institute of New Jersey, Newark, NJ 07103, USA
| | - Bin Tian
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School and Rutgers Cancer Institute of New Jersey, Newark, NJ 07103, USA
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25
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Ruthig VA, Friedersdorf MB, Garness JA, Munger SC, Bunce C, Keene JD, Capel B. The RNA-binding protein DND1 acts sequentially as a negative regulator of pluripotency and a positive regulator of epigenetic modifiers required for germ cell reprogramming. Development 2019; 146:dev175950. [PMID: 31253634 PMCID: PMC6803376 DOI: 10.1242/dev.175950] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 06/20/2019] [Indexed: 12/18/2022]
Abstract
The adult spermatogonial stem cell population arises from pluripotent primordial germ cells (PGCs) that enter the fetal testis around embryonic day (E)10.5. PGCs undergo rapid mitotic proliferation, then enter prolonged cell cycle arrest (G1/G0), during which they transition to pro-spermatogonia. In mice homozygous for the Ter mutation in the RNA-binding protein Dnd1 (Dnd1Ter/Ter ), many male germ cells (MGCs) fail to enter G1/G0 and instead form teratomas: tumors containing many embryonic cell types. To investigate the origin of these tumors, we sequenced the MGC transcriptome in Dnd1Ter/Ter mutants at E12.5, E13.5 and E14.5, immediately prior to teratoma formation, and correlated this information with DO-RIP-Seq-identified DND1 direct targets. Consistent with previous results, we found DND1 controls downregulation of many genes associated with pluripotency and active cell cycle, including mTor, Hippo and Bmp/Nodal signaling pathway elements. However, DND1 targets also include genes associated with male differentiation, including a large group of chromatin regulators activated in wild-type but not mutant MGCs during the E13.5 and E14.5 transition. Results suggest multiple DND1 functions and link DND1 to initiation of epigenetic modifications in MGCs.
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Affiliation(s)
- Victor A Ruthig
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Matthew B Friedersdorf
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Jason A Garness
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | | | - Corey Bunce
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Jack D Keene
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Blanche Capel
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
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Attig J, Ule J. Genomic Accumulation of Retrotransposons Was Facilitated by Repressive RNA-Binding Proteins: A Hypothesis. Bioessays 2019; 41:e1800132. [DOI: 10.1002/bies.201800132] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 11/14/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Jan Attig
- Dr. J. Attig, Prof. J. Ule; The Francis Crick Institute; 1 Midland Road London NW1 1AT UK
| | - Jernej Ule
- Dr. J. Attig, Prof. J. Ule; The Francis Crick Institute; 1 Midland Road London NW1 1AT UK
- Prof. J. Ule; Department of Molecular Neuroscience; UCL Institute of Neurology; Queen Square London WC1N 3BG UK
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27
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Pirogov SA, Maksimenko OG, Georgiev PG. Transposable Elements in the Evolution of Gene Regulatory Networks. RUSS J GENET+ 2019. [DOI: 10.1134/s1022795419010113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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28
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Wang R, Zheng D, Yehia G, Tian B. A compendium of conserved cleavage and polyadenylation events in mammalian genes. Genome Res 2018; 28:1427-1441. [PMID: 30143597 PMCID: PMC6169888 DOI: 10.1101/gr.237826.118] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Accepted: 08/08/2018] [Indexed: 12/22/2022]
Abstract
Cleavage and polyadenylation is essential for 3' end processing of almost all eukaryotic mRNAs. Recent studies have shown widespread alternative cleavage and polyadenylation (APA) events leading to mRNA isoforms with different 3' UTRs and/or coding sequences. Here, we present a compendium of conserved cleavage and polyadenylation sites (PASs) in mammalian genes, based on approximately 1.2 billion 3' end sequencing reads from more than 360 human, mouse, and rat samples. We show that ∼80% of mammalian mRNA genes contain at least one conserved PAS, and ∼50% have conserved APA events. PAS conservation generally reduces promiscuous 3' end processing, stabilizing gene expression levels across species. Conservation of APA correlates with gene age, gene expression features, and gene functions. Genes with certain functions, such as cell morphology, cell proliferation, and mRNA metabolism, are particularly enriched with conserved APA events. Whereas tissue-specific genes typically have a low APA rate, brain-specific genes tend to evolve APA. In addition, we show enrichment of mRNA destabilizing motifs in alternative 3' UTR sequences, leading to substantial differences in mRNA stability between 3' UTR isoforms. Using conserved PASs, we reveal sequence motifs surrounding APA sites and a preference of adenosine at the cleavage site. Furthermore, we show that mutations of U-rich motifs around the PAS often accompany APA profile differences between species. Analysis of lncRNA PASs indicates a mechanism of PAS fixation through evolution of A-rich motifs. Taken together, our results present a comprehensive view of PAS evolution in mammals, and a phylogenic perspective on APA functions.
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Affiliation(s)
- Ruijia Wang
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
- Rutgers Cancer Institute of New Jersey, Newark, New Jersey 07103, USA
| | - Dinghai Zheng
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
- Rutgers Cancer Institute of New Jersey, Newark, New Jersey 07103, USA
| | - Ghassan Yehia
- Genome Editing Core Facility, Rutgers University, New Brunswick, New Jersey 08901, USA
| | - Bin Tian
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
- Rutgers Cancer Institute of New Jersey, Newark, New Jersey 07103, USA
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29
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Wang R, Zheng D, Yehia G, Tian B. A compendium of conserved cleavage and polyadenylation events in mammalian genes. Genome Res 2018. [PMID: 30143597 DOI: 10.1101/gr.237826.118.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Abstract
Cleavage and polyadenylation is essential for 3' end processing of almost all eukaryotic mRNAs. Recent studies have shown widespread alternative cleavage and polyadenylation (APA) events leading to mRNA isoforms with different 3' UTRs and/or coding sequences. Here, we present a compendium of conserved cleavage and polyadenylation sites (PASs) in mammalian genes, based on approximately 1.2 billion 3' end sequencing reads from more than 360 human, mouse, and rat samples. We show that ∼80% of mammalian mRNA genes contain at least one conserved PAS, and ∼50% have conserved APA events. PAS conservation generally reduces promiscuous 3' end processing, stabilizing gene expression levels across species. Conservation of APA correlates with gene age, gene expression features, and gene functions. Genes with certain functions, such as cell morphology, cell proliferation, and mRNA metabolism, are particularly enriched with conserved APA events. Whereas tissue-specific genes typically have a low APA rate, brain-specific genes tend to evolve APA. In addition, we show enrichment of mRNA destabilizing motifs in alternative 3' UTR sequences, leading to substantial differences in mRNA stability between 3' UTR isoforms. Using conserved PASs, we reveal sequence motifs surrounding APA sites and a preference of adenosine at the cleavage site. Furthermore, we show that mutations of U-rich motifs around the PAS often accompany APA profile differences between species. Analysis of lncRNA PASs indicates a mechanism of PAS fixation through evolution of A-rich motifs. Taken together, our results present a comprehensive view of PAS evolution in mammals, and a phylogenic perspective on APA functions.
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Affiliation(s)
- Ruijia Wang
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
- Rutgers Cancer Institute of New Jersey, Newark, New Jersey 07103, USA
| | - Dinghai Zheng
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
- Rutgers Cancer Institute of New Jersey, Newark, New Jersey 07103, USA
| | - Ghassan Yehia
- Genome Editing Core Facility, Rutgers University, New Brunswick, New Jersey 08901, USA
| | - Bin Tian
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
- Rutgers Cancer Institute of New Jersey, Newark, New Jersey 07103, USA
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30
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Attig J, Agostini F, Gooding C, Chakrabarti AM, Singh A, Haberman N, Zagalak JA, Emmett W, Smith CWJ, Luscombe NM, Ule J. Heteromeric RNP Assembly at LINEs Controls Lineage-Specific RNA Processing. Cell 2018; 174:1067-1081.e17. [PMID: 30078707 PMCID: PMC6108849 DOI: 10.1016/j.cell.2018.07.001] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 04/23/2018] [Accepted: 07/01/2018] [Indexed: 12/30/2022]
Abstract
Long mammalian introns make it challenging for the RNA processing machinery to identify exons accurately. We find that LINE-derived sequences (LINEs) contribute to this selection by recruiting dozens of RNA-binding proteins (RBPs) to introns. This includes MATR3, which promotes binding of PTBP1 to multivalent binding sites within LINEs. Both RBPs repress splicing and 3' end processing within and around LINEs. Notably, repressive RBPs preferentially bind to evolutionarily young LINEs, which are located far from exons. These RBPs insulate the LINEs and the surrounding intronic regions from RNA processing. Upon evolutionary divergence, changes in RNA motifs within LINEs lead to gradual loss of their insulation. Hence, older LINEs are located closer to exons, are a common source of tissue-specific exons, and increasingly bind to RBPs that enhance RNA processing. Thus, LINEs are hubs for the assembly of repressive RBPs and also contribute to the evolution of new, lineage-specific transcripts in mammals. VIDEO ABSTRACT.
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Affiliation(s)
- Jan Attig
- The Francis Crick Institute, Midland Road 1, Kings Cross, London NW1 1AT, UK; Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK.
| | - Federico Agostini
- The Francis Crick Institute, Midland Road 1, Kings Cross, London NW1 1AT, UK
| | - Clare Gooding
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Anob M Chakrabarti
- The Francis Crick Institute, Midland Road 1, Kings Cross, London NW1 1AT, UK; Department of Genetics, Environment and Evolution, UCL Genetics Institute, Gower Street, London WC1E 6BT, UK
| | - Aarti Singh
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; Department of Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London NW1 0TU, UK
| | - Nejc Haberman
- The Francis Crick Institute, Midland Road 1, Kings Cross, London NW1 1AT, UK; Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Julian A Zagalak
- The Francis Crick Institute, Midland Road 1, Kings Cross, London NW1 1AT, UK; Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Warren Emmett
- The Francis Crick Institute, Midland Road 1, Kings Cross, London NW1 1AT, UK; Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; Department of Genetics, Environment and Evolution, UCL Genetics Institute, Gower Street, London WC1E 6BT, UK
| | - Christopher W J Smith
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Nicholas M Luscombe
- The Francis Crick Institute, Midland Road 1, Kings Cross, London NW1 1AT, UK; Department of Genetics, Environment and Evolution, UCL Genetics Institute, Gower Street, London WC1E 6BT, UK; Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
| | - Jernej Ule
- The Francis Crick Institute, Midland Road 1, Kings Cross, London NW1 1AT, UK; Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK.
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31
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Schaefke B, Sun W, Li YS, Fang L, Chen W. The evolution of posttranscriptional regulation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1485. [PMID: 29851258 DOI: 10.1002/wrna.1485] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 04/23/2018] [Accepted: 04/26/2018] [Indexed: 12/13/2022]
Abstract
"DNA makes RNA makes protein." After transcription, mRNAs undergo a series of intertwining processes to be finally translated into functional proteins. The "posttranscriptional" regulation (PTR) provides cells an extended option to fine-tune their proteomes. To meet the demands of complex organism development and the appropriate response to environmental stimuli, every step in these processes needs to be finely regulated. Moreover, changes in these regulatory processes are important driving forces underlying the evolution of phenotypic differences across different species. The major PTR mechanisms discussed in this review include the regulation of splicing, polyadenylation, decay, and translation. For alternative splicing and polyadenylation, we mainly discuss their evolutionary dynamics and the genetic changes underlying the regulatory differences in cis-elements versus trans-factors. For mRNA decay and translation, which, together with transcription, determine the cellular RNA or protein abundance, we focus our discussion on how their divergence coordinates with transcriptional changes to shape the evolution of gene expression. Then to highlight the importance of PTR in the evolution of higher complexity, we focus on their roles in two major phenomena during eukaryotic evolution: the evolution of multicellularity and the division of labor between different cell types and tissues; and the emergence of diverse, often highly specialized individual phenotypes, especially those concerning behavior in eusocial insects. This article is categorized under: RNA Evolution and Genomics > RNA and Ribonucleoprotein Evolution Translation > Translation Regulation RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
- Bernhard Schaefke
- Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Wei Sun
- Department of Biology, Southern University of Science and Technology, Shenzhen, China.,Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California San Francisco, San Francisco
| | - Yi-Sheng Li
- Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Liang Fang
- Department of Biology, Southern University of Science and Technology, Shenzhen, China.,Medi-X Institute, SUSTech Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen, China
| | - Wei Chen
- Department of Biology, Southern University of Science and Technology, Shenzhen, China.,Medi-X Institute, SUSTech Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen, China
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32
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Hunter N. Oocyte Quality Control: Causes, Mechanisms, and Consequences. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2018; 82:235-247. [PMID: 29743337 DOI: 10.1101/sqb.2017.82.035394] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Oocyte quality and number are key determinants of reproductive life span and success. These variables are shaped in part by the elimination of oocytes that experience problems during the early stages of meiosis. Meiotic prophase-I marks an extended period of genome vulnerability in which epigenetic reprogramming unleashes retroelements and hundreds of DNA double-strand breaks (DSBs) are inflicted to initiate the programmed recombination required for accurate chromosome segregation at the first meiotic division. Expression of LINE-1 retroelements perturbs several aspects of meiotic prophase and is associated with oocyte death during the early stages of meiotic prophase I. Defects in chromosome synapsis and recombination also trigger oocyte loss, but typically at a later stage, as cells transition into quiescence and form primordial follicles. Interrelated pathways that signal defects in DSB repair and chromosome synapsis mediate this late oocyte attrition. Here, I review our current understanding of early and late oocyte attrition based on studies in mouse and describe how these processes appear to be both distinct and overlapping and how they help balance the quality and size of oocyte reserves to maximize fecundity.
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Affiliation(s)
- Neil Hunter
- Howard Hughes Medical Institute, University of California, Davis, Davis, California 95616.,Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California 95616.,Department of Molecular and Cellular Biology, University of California, Davis, Davis, California 95616.,Department of Cell Biology and Human Anatomy, University of California, Davis, Davis, California 95616
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33
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Lavi E, Carmel L. Alu exaptation enriches the human transcriptome by introducing new gene ends. RNA Biol 2018; 15:715-725. [PMID: 29493382 DOI: 10.1080/15476286.2018.1429880] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In mammals, transposable elements are largely silenced, but under fortuitous circumstances may be co-opted to play a functional role. Here, we show that when Alu elements are inserted within or nearby genes in sense orientation, they may contribute to the transcriptome diversity by forming new cleavage and polyadenylation sites. We mapped these new gene ends in human onto the Alu sequence and identified three hotspots of cleavage and polyadenylation site formation. Interestingly, the native Alu sequence does not contain any canonical polyadenylation signal. We therefore studied what evolutionary processes might explain the formation of these specific hotspots of novel gene ends. We show that two of the three hotspots might have emerged from mutational processes that turned sequences that resemble polyadenylation signals into full-blown canonical signals, whereas one hotspot is tightly linked to the process of Alu insertion into the genome. Overall, Alu elements may lie behind the formation of 302 new gene end variants, affecting a total of 243 genes. Intergenic Alu elements may elongate genes by creating a downstream cleavage site, intronic Alu elements may lead to gene variants which code for truncated proteins, and 3'UTR Alu elements may result in gene variants with alternative 3'UTR.
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Affiliation(s)
- Eitan Lavi
- a Department of Genetics , The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem , Jerusalem , Israel
| | - Liran Carmel
- a Department of Genetics , The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem , Jerusalem , Israel
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34
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Alzheimer's brains show inter-related changes in RNA and lipid metabolism. Neurobiol Dis 2017; 106:1-13. [PMID: 28630030 PMCID: PMC5560656 DOI: 10.1016/j.nbd.2017.06.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/17/2017] [Accepted: 06/12/2017] [Indexed: 12/18/2022] Open
Abstract
Alzheimer's disease (AD) involves changes in both lipid and RNA metabolism, but it remained unknown if these differences associate with AD's cognition and/or post-mortem neuropathology indices. Here, we report RNA-sequencing evidence of inter-related associations between lipid processing, cognition level, and AD neuropathology. In two unrelated cohorts, we identified pathway-enriched facilitation of lipid processing and alternative splicing genes, including the neuronal-enriched NOVA1 and hnRNPA1. Specifically, this association emerged in temporal lobe tissue samples from donors where postmortem evidence demonstrated AD neuropathology, but who presented normal cognition proximate to death. The observed changes further associated with modified ATP synthesis and mitochondrial transcripts, indicating metabolic relevance; accordingly, mass-spectrometry-derived lipidomic profiles distinguished between individuals with and without cognitive impairment prior to death. In spite of the limited group sizes, tissues from persons with both cognitive impairment and AD pathology showed elevation in several drug-targeted genes of other brain, vascular and autoimmune disorders, accompanied by pathology-related increases in distinct lipid processing transcripts, and in the RNA metabolism genes hnRNPH2, TARDBP, CLP1 and EWSR1. To further detect 3'-polyadenylation variants, we employed multiple cDNA primer pairs. This identified variants that showed limited differences in scope and length between the tested cohorts, yet enabled superior clustering of demented and non-demented AD brains versus controls compared to total mRNA expression values. Our findings indicate inter-related cognition-associated differences in AD's lipid processing, alternative splicing and 3'-polyadenylation, calling for pursuing the underlying psychological and therapeutics implications.
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35
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Chen LL, Yang L. ALU ternative Regulation for Gene Expression. Trends Cell Biol 2017; 27:480-490. [DOI: 10.1016/j.tcb.2017.01.002] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 12/14/2016] [Accepted: 01/05/2017] [Indexed: 12/23/2022]
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36
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Abstract
In eukaryote genomes, the polyadenylation site marks termination of mature RNA transcripts by a poly-adenine tail. The polyadenylation site is recognized by a dynamic protein complex, among which the poly-adenine-binding protein nuclear1 plays a key role. Reduced poly-adenine-binding protein nuclear1 levels are found in aged muscles and are even lower in oculopharyngeal muscular dystrophy patients. Oculopharyngeal muscular dystrophy is a rare, late onset autosomal dominant myopathy, and is caused by an alanine expansion mutation in poly-adenine-binding protein nuclear1. Mutant poly-adenine-binding protein nuclear1 forms insoluble nuclear aggregates leading to depletion of functional poly-adenine-binding protein nuclear1 levels. In oculopharyngeal muscular dystrophy models, increased utilization of proximal polyadenylation sites has been observed in tandem 3'-untranslated regions, and most often cause gene upregulation. However, global alterations in expression profiles canonly partly be explained by polyadenylation site switches within the most distal 3'-untranslated region. Most poly-adenine signals are found at the distal 3'-untranslated region, but a significant part is also found in internal gene regions, like introns, exons, and internal 3'-untranslated regions. Here, we investigated poly-adenine-binding protein nuclear1's role in polyadenylation site utilization in internal gene regions. In the quadriceps muscle of oculopharyngeal muscular dystrophy mice expressing expPABPN1 we found significant polyadenylation site switches between gene regions in 17% of genes with polyadenylation site in multiple regions (N = 574; 5% False Discovery Rate). Polyadenylation site switches between gene regions were associated with differences in transcript expression levels and alterations in open reading frames. Transcripts ending at internal polyadenylation site were confirmed in tibialis anterior muscles from the same mice and in mouse muscle cell cultures overexpressing expPABPN1. The polyadenylation site switches were associated with nuclear accumulation of full-length transcripts. Our results provide further insights into the diverse roles of poly-adenine-binding protein nuclear1 in the post-transcriptional control of muscle gene expression and its relevance for oculopharyngeal muscular dystrophy pathology and muscle aging.
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37
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Translational repression by a miniature inverted-repeat transposable element in the 3' untranslated region. Nat Commun 2017; 8:14651. [PMID: 28256530 PMCID: PMC5338036 DOI: 10.1038/ncomms14651] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 01/18/2017] [Indexed: 12/18/2022] Open
Abstract
Transposable elements constitute a substantial portion of eukaryotic genomes and contribute to genomic variation, function, and evolution. Miniature inverted-repeat transposable elements (MITEs), as DNA transposons, are widely distributed in plant and animal genomes. Previous studies have suggested that retrotransposons act as translational regulators; however, it remains unknown how host mRNAs are influenced by DNA transposons. Here we report a translational repression mechanism mediated by a stowaway-like MITE (sMITE) embedded in the 3'-untranslated region (3'-UTR) of Ghd2, a member of the CCT (CONSTANS [CO], CO-LIKE and TIMING OF CAB1) gene family in rice. Ghd2 regulates important agronomic traits, including grain number, plant height and heading date. Interestingly, the translational repression of Ghd2 by the sMITE mainly relies on Dicer-like 3a (OsDCL3a). Furthermore, other MITEs in the 3'-UTRs of different rice genes exhibit a similar effect on translational repression, thus suggesting that MITEs may exert a general regulatory function at the translational level.
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Abstract
Alternative polyadenylation (APA) is an RNA-processing mechanism that generates distinct 3' termini on mRNAs and other RNA polymerase II transcripts. It is widespread across all eukaryotic species and is recognized as a major mechanism of gene regulation. APA exhibits tissue specificity and is important for cell proliferation and differentiation. In this Review, we discuss the roles of APA in diverse cellular processes, including mRNA metabolism, protein diversification and protein localization, and more generally in gene regulation. We also discuss the molecular mechanisms underlying APA, such as variation in the concentration of core processing factors and RNA-binding proteins, as well as transcription-based regulation.
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Warren IA, Naville M, Chalopin D, Levin P, Berger CS, Galiana D, Volff JN. Evolutionary impact of transposable elements on genomic diversity and lineage-specific innovation in vertebrates. Chromosome Res 2016; 23:505-31. [PMID: 26395902 DOI: 10.1007/s10577-015-9493-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Since their discovery, a growing body of evidence has emerged demonstrating that transposable elements are important drivers of species diversity. These mobile elements exhibit a great variety in structure, size and mechanisms of transposition, making them important putative actors in organism evolution. The vertebrates represent a highly diverse and successful lineage that has adapted to a wide range of different environments. These animals also possess a rich repertoire of transposable elements, with highly diverse content between lineages and even between species. Here, we review how transposable elements are driving genomic diversity and lineage-specific innovation within vertebrates. We discuss the large differences in TE content between different vertebrate groups and then go on to look at how they affect organisms at a variety of levels: from the structure of chromosomes to their involvement in the regulation of gene expression, as well as in the formation and evolution of non-coding RNAs and protein-coding genes. In the process of doing this, we highlight how transposable elements have been involved in the evolution of some of the key innovations observed within the vertebrate lineage, driving the group's diversity and success.
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Affiliation(s)
- Ian A Warren
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Magali Naville
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Domitille Chalopin
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France.,Department of Genetics, University of Georgia, Athens, Georgia, 30602, USA
| | - Perrine Levin
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Chloé Suzanne Berger
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Delphine Galiana
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France.
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Distribution patterns and impact of transposable elements in genes of green algae. Gene 2016; 594:151-159. [PMID: 27614292 DOI: 10.1016/j.gene.2016.09.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 09/01/2016] [Accepted: 09/06/2016] [Indexed: 11/23/2022]
Abstract
Transposable elements (TEs) are DNA sequences able to transpose in the host genome, a remarkable feature that enables them to influence evolutive trajectories of species. An investigation about the TE distribution and TE impact in different gene regions of the green algae species Chlamydomonas reinhardtii and Volvox carteri was performed. Our results indicate that TEs are very scarce near introns boundaries, suggesting that insertions in this region are negatively selected. This contrasts with previous results showing enrichment of tandem repeats in introns boundaries and suggests that different evolutionary forces are acting in these different classes of repeats. Despite the relatively low abundance of TEs in the genome of green algae when compared to mammals, the proportion of poly(A) sites derived from TEs found in C. reinhardtii was similar to that described in human and mice. This fact, associated with the enrichment of TEs in gene 5' and 3' flanks of C. reinhardtii, opens up the possibility that TEs may have considerably contributed for gene regulatory sequences evolution in this species. Moreover, it was possible identify several instances of TE exonization for C. reinhardtii, with a particularly interesting case from a gene coding for Condensin II, a protein involved in the maintenance of chromosomal structure, where the addition of a transposomal PHD finger may contribute to binding specificity of this protein. Taken together, our results suggest that the low abundance of TEs in green algae genomes is correlated with a strict negative selection process, combined with the retention of copies that contribute positively with gene structures.
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Kainov YA, Aushev VN, Naumenko SA, Tchevkina EM, Bazykin GA. Complex Selection on Human Polyadenylation Signals Revealed by Polymorphism and Divergence Data. Genome Biol Evol 2016; 8:1971-9. [PMID: 27324920 PMCID: PMC4943204 DOI: 10.1093/gbe/evw137] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2016] [Indexed: 12/19/2022] Open
Abstract
Polyadenylation is a step of mRNA processing which is crucial for its expression and stability. The major polyadenylation signal (PAS) represents a nucleotide hexamer that adheres to the AATAAA consensus sequence. Over a half of human genes have multiple cleavage and polyadenylation sites, resulting in a great diversity of transcripts differing in function, stability, and translational activity. Here, we use available whole-genome human polymorphism data together with data on interspecies divergence to study the patterns of selection acting on PAS hexamers. Common variants of PAS hexamers are depleted of single nucleotide polymorphisms (SNPs), and SNPs within PAS hexamers have a reduced derived allele frequency (DAF) and increased conservation, indicating prevalent negative selection; at the same time, the SNPs that "improve" the PAS (i.e., those leading to higher cleavage efficiency) have increased DAF, compared to those that "impair" it. SNPs are rarer at PAS of "unique" polyadenylation sites (one site per gene); among alternative polyadenylation sites, at the distal PAS and at exonic PAS. Similar trends were observed in DAFs and divergence between species of placental mammals. Thus, selection permits PAS mutations mainly at redundant and/or weakly functional PAS. Nevertheless, a fraction of the SNPs at PAS hexamers likely affect gene functions; in particular, some of the observed SNPs are associated with disease.
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Affiliation(s)
- Yaroslav A Kainov
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom Oncogenes Regulation Department, N.N. Blokhin Russian Cancer Research Center, Institute of Carcinogenesis, Moscow, Russia
| | - Vasily N Aushev
- Oncogenes Regulation Department, N.N. Blokhin Russian Cancer Research Center, Institute of Carcinogenesis, Moscow, Russia Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, New York
| | - Sergey A Naumenko
- Institute for Information Transmission Problems (Kharkevich Institute) of the Russian Academy of Sciences, Moscow, Russia Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, Canada
| | - Elena M Tchevkina
- Oncogenes Regulation Department, N.N. Blokhin Russian Cancer Research Center, Institute of Carcinogenesis, Moscow, Russia
| | - Georgii A Bazykin
- Institute for Information Transmission Problems (Kharkevich Institute) of the Russian Academy of Sciences, Moscow, Russia Skolkovo Institute of Science and Technology, Skolkovo, Russia Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Russia Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Russia Pirogov Russian National Research Medical University, Moscow, Russia
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Guo C, Spinelli M, Liu M, Li QQ, Liang C. A Genome-wide Study of "Non-3UTR" Polyadenylation Sites in Arabidopsis thaliana. Sci Rep 2016; 6:28060. [PMID: 27301740 PMCID: PMC4908657 DOI: 10.1038/srep28060] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 05/20/2016] [Indexed: 11/18/2022] Open
Abstract
Alternative polyadenylation has been recognized as a key contributor of gene expression regulation by generating different transcript isoforms with altered 3′ ends. Although polyadenylation is well known for marking the end of a 3′ UTR, an increasing number of studies have reported previously less-addressed polyadenylation events located in other parts of genes in many eukaryotic organisms. These other locations include 5′ UTRs, introns and coding sequences (termed herein as non-3UTR), as well as antisense and intergenic polyadenlation. Focusing on the non-3UTR polyadenylation sites (n3PASs), we detected and characterized more than 11000 n3PAS clusters in the Arabidopsis genome using poly(A)-tag sequencing data (PAT-Seq). Further analyses suggested that the occurrence of these n3PASs were positively correlated with certain characteristics of their respective host genes, including the presence of spliced, diminutive or diverse beginning of 5′ UTRs, number of introns and whether introns have extreme lengths. The interaction of the host genes with surrounding genetic elements, like a convergently overlapped gene and associated transposable element, may contribute to the generation of a n3PAS as well. Collectively, these results provide a better understanding of n3PASs, and offer some new insights of the underlying mechanisms for non-3UTR polyadenylation and its regulation in plants.
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Affiliation(s)
- Cheng Guo
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | | | - Man Liu
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | - Qingshun Q Li
- Key Laboratory of the Ministry of Education for Costal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China.,Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA
| | - Chun Liang
- Department of Biology, Miami University, Oxford, OH 45056, USA
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Seibt KM, Wenke T, Muders K, Truberg B, Schmidt T. Short interspersed nuclear elements (SINEs) are abundant in Solanaceae and have a family-specific impact on gene structure and genome organization. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 86:268-285. [PMID: 26996788 DOI: 10.1111/tpj.13170] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/11/2016] [Accepted: 03/14/2016] [Indexed: 06/05/2023]
Abstract
Short interspersed nuclear elements (SINEs) are highly abundant non-autonomous retrotransposons that are widespread in plants. They are short in size, non-coding, show high sequence diversity, and are therefore mostly not or not correctly annotated in plant genome sequences. Hence, comparative studies on genomic SINE populations are rare. To explore the structural organization and impact of SINEs, we comparatively investigated the genome sequences of the Solanaceae species potato (Solanum tuberosum), tomato (Solanum lycopersicum), wild tomato (Solanum pennellii), and two pepper cultivars (Capsicum annuum). Based on 8.5 Gbp sequence data, we annotated 82 983 SINE copies belonging to 10 families and subfamilies on a base pair level. Solanaceae SINEs are dispersed over all chromosomes with enrichments in distal regions. Depending on the genome assemblies and gene predictions, 30% of all SINE copies are associated with genes, particularly frequent in introns and untranslated regions (UTRs). The close association with genes is family specific. More than 10% of all genes annotated in the Solanaceae species investigated contain at least one SINE insertion, and we found genes harbouring up to 16 SINE copies. We demonstrate the involvement of SINEs in gene and genome evolution including the donation of splice sites, start and stop codons and exons to genes, enlargement of introns and UTRs, generation of tandem-like duplications and transduction of adjacent sequence regions.
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Affiliation(s)
- Kathrin M Seibt
- Institute of Botany, Technische Universität Dresden, 01062, Dresden, Germany
| | - Torsten Wenke
- Institute of Botany, Technische Universität Dresden, 01062, Dresden, Germany
| | | | | | - Thomas Schmidt
- Institute of Botany, Technische Universität Dresden, 01062, Dresden, Germany
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Abstract
Transposable elements (TEs) are both a boon and a bane to eukaryotic organisms, depending on where they integrate into the genome and how their sequences function once integrated. We focus on two types of TEs: long interspersed elements (LINEs) and short interspersed elements (SINEs). LINEs and SINEs are retrotransposons; that is, they transpose via an RNA intermediate. We discuss how LINEs and SINEs have expanded in eukaryotic genomes and contribute to genome evolution. An emerging body of evidence indicates that LINEs and SINEs function to regulate gene expression by affecting chromatin structure, gene transcription, pre-mRNA processing, or aspects of mRNA metabolism. We also describe how adenosine-to-inosine editing influences SINE function and how ongoing retrotransposition is countered by the body's defense mechanisms.
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Affiliation(s)
- Reyad A Elbarbary
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA. Center for RNA Biology, University of Rochester, Rochester, NY, USA
| | - Bronwyn A Lucas
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA. Center for RNA Biology, University of Rochester, Rochester, NY, USA
| | - Lynne E Maquat
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA. Center for RNA Biology, University of Rochester, Rochester, NY, USA. Department of Oncology, Wilmot Cancer Institute, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA.
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Kim EZ, Wespiser AR, Caffrey DR. The domain structure and distribution of Alu elements in long noncoding RNAs and mRNAs. RNA (NEW YORK, N.Y.) 2016; 22:254-264. [PMID: 26654912 PMCID: PMC4712675 DOI: 10.1261/rna.048280.114] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 11/12/2015] [Indexed: 06/05/2023]
Abstract
Approximately 75% of the human genome is transcribed and many of these spliced transcripts contain primate-specific Alu elements, the most abundant mobile element in the human genome. The majority of exonized Alu elements are located in long noncoding RNAs (lncRNAs) and the untranslated regions of mRNA, with some performing molecular functions. To further assess the potential for Alu elements to be repurposed as functional RNA domains, we investigated the distribution and evolution of Alu elements in spliced transcripts. Our analysis revealed that Alu elements are underrepresented in mRNAs and lncRNAs, suggesting that most exonized Alu elements arising in the population are rare or deleterious to RNA function. When mRNAs and lncRNAs retain exonized Alu elements, they have a clear preference for Alu dimers, left monomers, and right monomers. mRNAs often acquire Alu elements when their genes are duplicated within Alu-rich regions. In lncRNAs, reverse-oriented Alu elements are significantly enriched and are not restricted to the 3' and 5' ends. Both lncRNAs and mRNAs primarily contain the Alu J and S subfamilies that were amplified relatively early in primate evolution. Alu J subfamilies are typically overrepresented in lncRNAs, whereas the Alu S dimer is overrepresented in mRNAs. The sequences of Alu dimers tend to be constrained in both lncRNAs and mRNAs, whereas the left and right monomers are constrained within particular Alu subfamilies and classes of RNA. Collectively, these findings suggest that Alu-containing RNAs are capable of forming stable structures and that some of these Alu domains might have novel biological functions.
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Affiliation(s)
- Eugene Z Kim
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Adam R Wespiser
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Daniel R Caffrey
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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46
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Li W, Park JY, Zheng D, Hoque M, Yehia G, Tian B. Alternative cleavage and polyadenylation in spermatogenesis connects chromatin regulation with post-transcriptional control. BMC Biol 2016; 14:6. [PMID: 26801249 PMCID: PMC4724118 DOI: 10.1186/s12915-016-0229-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/12/2016] [Indexed: 11/10/2022] Open
Abstract
Background Most mammalian genes display alternative cleavage and polyadenylation (APA). Previous studies have indicated preferential expression of APA isoforms with short 3’ untranslated regions (3’UTRs) in testes. Results By deep sequencing of the 3’ end region of poly(A) + transcripts, we report widespread shortening of 3’UTR through APA during the first wave of spermatogenesis in mouse, with 3’UTR size being the shortest in spermatids. Using genes without APA as a control, we show that shortening of 3’UTR eliminates destabilizing elements, such as U-rich elements and transposable elements, which appear highly potent during spermatogenesis. We additionally found widespread regulation of APA events in introns and exons that can affect the coding sequence of transcripts and global activation of antisense transcripts upstream of the transcription start site, suggesting modulation of splicing and initiation of transcription during spermatogenesis. Importantly, genes that display significant 3’UTR shortening tend to have functions critical for further sperm maturation, and testis-specific genes display greater 3’UTR shortening than ubiquitously expressed ones, indicating functional relevance of APA to spermatogenesis. Interestingly, genes with shortened 3’UTRs tend to have higher RNA polymerase II and H3K4me3 levels in spermatids as compared to spermatocytes, features previously known to be associated with open chromatin state. Conclusions Our data suggest that open chromatin may create a favorable cis environment for 3’ end processing, leading to global shortening of 3’UTR during spermatogenesis. mRNAs with shortened 3’UTRs are relatively stable thanks to evasion of powerful mRNA degradation mechanisms acting on 3’UTR elements. Stable mRNAs generated in spermatids may be important for protein production at later stages of sperm maturation, when transcription is globally halted. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0229-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wencheng Li
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Ji Yeon Park
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Dinghai Zheng
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Mainul Hoque
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Ghassan Yehia
- Transgenic Core Facility, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Bin Tian
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA. .,Rutgers Cancer Institute of New Jersey, Newark, NJ, USA.
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Tajnik M, Vigilante A, Braun S, Hänel H, Luscombe NM, Ule J, Zarnack K, König J. Intergenic Alu exonisation facilitates the evolution of tissue-specific transcript ends. Nucleic Acids Res 2015; 43:10492-505. [PMID: 26400176 PMCID: PMC4666398 DOI: 10.1093/nar/gkv956] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 09/09/2015] [Accepted: 09/10/2015] [Indexed: 11/14/2022] Open
Abstract
The 3' untranslated regions (3' UTRs) of transcripts serve as important hubs for posttranscriptional gene expression regulation. Here, we find that the exonisation of intergenic Alu elements introduced new terminal exons and polyadenylation sites during human genome evolution. While Alu exonisation from introns has been described previously, we shed light on a novel mechanism to create alternative 3' UTRs, thereby opening opportunities for differential posttranscriptional regulation. On the mechanistic level, we show that intergenic Alu exonisation can compete both with alternative splicing and polyadenylation in the upstream gene. Notably, the Alu-derived isoforms are often expressed in a tissue-specific manner, and the Alu-derived 3' UTRs can alter mRNA stability. In summary, we demonstrate that intergenic elements can affect processing of preceding genes, and elucidate how intergenic Alu exonisation can contribute to tissue-specific posttranscriptional regulation by expanding the repertoire of 3' UTRs.
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Affiliation(s)
- Mojca Tajnik
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| | - Alessandra Vigilante
- UCL Genetics Institute, Department of Genetics, Evolution & Environment, University College London, Gower Street, London WC1E 6BT, UK Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Simon Braun
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Heike Hänel
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Nicholas M Luscombe
- UCL Genetics Institute, Department of Genetics, Evolution & Environment, University College London, Gower Street, London WC1E 6BT, UK Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK Okinawa Institute of Science & Technology, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan
| | - Jernej Ule
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Kathi Zarnack
- Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK Buchmann Institute for Molecular Life Sciences (BMLS), Max-von-Laue-Str. 15, 60438 Frankfurt, Germany
| | - Julian König
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
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Ayarpadikannan S, Lee HE, Han K, Kim HS. Transposable element-driven transcript diversification and its relevance to genetic disorders. Gene 2015; 558:187-94. [PMID: 25617522 DOI: 10.1016/j.gene.2015.01.039] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 01/13/2015] [Accepted: 01/20/2015] [Indexed: 12/14/2022]
Abstract
The human genome project and subsequent gene annotation projects have shown that the human genome contains 22,000-25,000 functional genes. Therefore, it is believed that the diversity of protein repertoire is achieved by the alternative splicing (AS) mechanism. Transposable elements (TEs) are mobile in nature and can therefore alter their position in the genome. The insertion of TEs into a new gene region can result in AS of a particular transcript through various mechanisms, including intron retention, and alternative donor or acceptor splice sites. TE-derived AS is thought to have played a part in primate evolution and in hominid radiation. However, TE-derived AS or genetic instability may sometimes result in genetic disorders. For the past two decades, numerous studies have been performed on TEs and their role in genomes. Accumulating evidence shows that the term 'junk DNA', previously used for TEs is a misnomer. Recent research has indicated that TEs may have clinical potential. However, to explore the feasibility of using TEs in clinical practice, additional studies are required. This review summarizes the available literature on TE-derived AS, alternative promoter, and alternative polyadenylation. The review covers the effects of TEs on coding genes and their clinical implications, and provides our perspectives and directions for future research.
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Affiliation(s)
- Selvam Ayarpadikannan
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Republic of Korea
| | - Hee-Eun Lee
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Republic of Korea
| | - Kyudong Han
- Department of Nanobiomedical Science, WCU Research Center, Dankook University, Cheonan 330-714, Republic of Korea
| | - Heui-Soo Kim
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Republic of Korea.
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Santana MF, Silva JCF, Mizubuti ESG, Araújo EF, Queiroz MV. Analysis of Tc1-Mariner elements in Sclerotinia sclerotiorum suggests recent activity and flexible transposases. BMC Microbiol 2014; 14:256. [PMID: 25281292 PMCID: PMC4188875 DOI: 10.1186/s12866-014-0256-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/25/2014] [Indexed: 12/12/2022] Open
Abstract
Background Sclerotinia sclerotiorum is a necrotrophic fungus that is pathogenic to many plants. Genomic analysis of its revealed transposable element expansion that has strongly influenced the evolutionary trajectory of several species. Transposons from the Tc1-Mariner superfamily are thought to be ubiquitous components of fungal genomes and are generally found in low copy numbers with large numbers of deleterious mutations in their transposase coding sequence. Results This study shows that the genome of S. sclerotiorum has a large number of copies of Tc1-Mariner transposons, and in silico analysis shows evidence that they were recently active. This finding was confirmed by expressed sequence tag (EST) analysis. Fourteen new Tc1-Mariner transposon families that were distributed throughout the genome were identified, and in some cases, due to the excision/retention of introns, different transcripts were observed for the same family, which might be the result of an efficient strategy to circumvent mutations that generate premature stop codons in the RNA sequence. In addition, the presence of these introns shows that the transposase protein has a flexible coding sequence and, consequently, conformation. No evidence for RIP-like gene silencing mechanisms, which are commonly found in fungi, was found in the identified Tc1-Mariner elements, and analysis of the genomic insertion sites of these elements showed that they were widely distributed throughout the genome with some copies located near the 3′ regions of genes. In particular, EST analysis demonstrated that one of these copies was co-expressed with a gene, which showed the potential for these elements to undergo exaptation. Conclusions Fourteen novel Tc1-Mariner families were characterized. Some families had evidence of introns, which might or might not be excised depending on the family or element in question, and this finding demonstrates a possible strategy for overcoming possible mutations that generate premature stop codons in a RNA sequence. Tc1-Mariner elements likely play an important role in the structure and evolution of the S. sclerotiorum genome.
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50
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Grau JH, Poustka AJ, Meixner M, Plötner J. LTR retroelements are intrinsic components of transcriptional networks in frogs. BMC Genomics 2014; 15:626. [PMID: 25056159 PMCID: PMC4131045 DOI: 10.1186/1471-2164-15-626] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 07/15/2014] [Indexed: 12/16/2022] Open
Abstract
Background LTR retroelements (LTR REs) constitute a major group of transposable elements widely distributed in eukaryotic genomes. Through their own mechanism of retrotranscription LTR REs enrich the genomic landscape by providing genetic variability, thus contributing to genome structure and organization. Nonetheless, transcriptomic activity of LTR REs still remains an obscure domain within cell, developmental, and organism biology. Results Here we present a first comparative analysis of LTR REs for anuran amphibians based on a full depth coverage transcriptome of the European pool frog, Pelophylax lessonae, the genome of the African clawed frog, Silurana tropicalis (release v7.1), and additional transcriptomes of S. tropicalis and Cyclorana alboguttata. We identified over 1000 copies of LTR REs from all four families (Bel/Pao, Ty1/Copia, Ty3/Gypsy, Retroviridae) in the genome of S. tropicalis and discovered transcripts of several of these elements in all RNA-seq datasets analyzed. Elements of the Ty3/Gypsy family were most active, especially Amn-san elements, which accounted for approximately 0.27% of the genome in Silurana. Some elements exhibited tissue specific expression patterns, for example Hydra1.1 and MuERV-like elements in Pelophylax. In S. tropicalis considerable transcription of LTR REs was observed during embryogenesis as soon as the embryonic genome became activated, i.e. at midblastula transition. In the course of embryonic development the spectrum of transcribed LTR REs changed; during gastrulation and neurulation MuERV-like and SnRV like retroviruses were abundantly transcribed while during organogenesis transcripts of the XEN1 retroviruses became much more active. Conclusions The differential expression of LTR REs during embryogenesis in concert with their tissue-specificity and the protein domains they encode are evidence for the functional roles these elements play as integrative parts of complex regulatory networks. Our results support the meanwhile widely accepted concept that retroelements are not simple “junk DNA” or “harmful genomic parasites” but essential components of the transcriptomic machinery in vertebrates. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-626) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- José Horacio Grau
- Dahlem Center for Genome Research and Medical Systems Biology, Fabeckstraße 60-62, 14195 Berlin, Germany.
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