1
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Jia H, Tan S, Cai Y, Guo Y, Shen J, Zhang Y, Ma H, Zhang Q, Chen J, Qiao G, Ruan J, Zhang YE. Low-input PacBio sequencing generates high-quality individual fly genomes and characterizes mutational processes. Nat Commun 2024; 15:5644. [PMID: 38969648 PMCID: PMC11226609 DOI: 10.1038/s41467-024-49992-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 06/20/2024] [Indexed: 07/07/2024] Open
Abstract
Long-read sequencing, exemplified by PacBio, revolutionizes genomics, overcoming challenges like repetitive sequences. However, the high DNA requirement ( > 1 µg) is prohibitive for small organisms. We develop a low-input (100 ng), low-cost, and amplification-free library-generation method for PacBio sequencing (LILAP) using Tn5-based tagmentation and DNA circularization within one tube. We test LILAP with two Drosophila melanogaster individuals, and generate near-complete genomes, surpassing preexisting single-fly genomes. By analyzing variations in these two genomes, we characterize mutational processes: complex transpositions (transposon insertions together with extra duplications and/or deletions) prefer regions characterized by non-B DNA structures, and gene conversion of transposons occurs on both DNA and RNA levels. Concurrently, we generate two complete assemblies for the endosymbiotic bacterium Wolbachia in these flies and similarly detect transposon conversion. Thus, LILAP promises a broad PacBio sequencing adoption for not only mutational studies of flies and their symbionts but also explorations of other small organisms or precious samples.
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Affiliation(s)
- Hangxing Jia
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
| | - Shengjun Tan
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
| | - Yingao Cai
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yanyan Guo
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jieyu Shen
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yaqiong Zhang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Huijing Ma
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Qingzhu Zhang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jinfeng Chen
- University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Gexia Qiao
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jue Ruan
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China.
| | - Yong E Zhang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
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2
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Wong EWP, Sahin M, Yang R, Lee U, Zhan YA, Misra R, Tomas F, Alomran N, Polyzos A, Lee CJ, Trieu T, Fundichely AM, Wiesner T, Rosowicz A, Cheng S, Liu C, Lallo M, Merghoub T, Hamard PJ, Koche R, Khurana E, Apostolou E, Zheng D, Chen Y, Leslie CS, Chi P. TAD hierarchy restricts poised LTR activation and loss of TAD hierarchy promotes LTR co-option in cancer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.31.596845. [PMID: 38895201 PMCID: PMC11185511 DOI: 10.1101/2024.05.31.596845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Transposable elements (TEs) are abundant in the human genome, and they provide the sources for genetic and functional diversity. The regulation of TEs expression and their functional consequences in physiological conditions and cancer development remain to be fully elucidated. Previous studies suggested TEs are repressed by DNA methylation and chromatin modifications. The effect of 3D chromatin topology on TE regulation remains elusive. Here, by integrating transcriptome and 3D genome architecture studies, we showed that haploinsufficient loss of NIPBL selectively activates alternative promoters at the long terminal repeats (LTRs) of the TE subclasses. This activation occurs through the reorganization of topologically associating domain (TAD) hierarchical structures and recruitment of proximal enhancers. These observations indicate that TAD hierarchy restricts transcriptional activation of LTRs that already possess open chromatin features. In cancer, perturbation of the hierarchical chromatin topology can lead to co-option of LTRs as functional alternative promoters in a context-dependent manner and drive aberrant transcriptional activation of novel oncogenes and other divergent transcripts. These data uncovered a new layer of regulatory mechanism of TE expression beyond DNA and chromatin modification in human genome. They also posit the TAD hierarchy dysregulation as a novel mechanism for alternative promoter-mediated oncogene activation and transcriptional diversity in cancer, which may be exploited therapeutically.
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3
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Graham JH, Schlachetzki JCM, Yang X, Breuss MW. Genomic Mosaicism of the Brain: Origin, Impact, and Utility. Neurosci Bull 2024; 40:759-776. [PMID: 37898991 PMCID: PMC11178748 DOI: 10.1007/s12264-023-01124-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/16/2023] [Indexed: 10/31/2023] Open
Abstract
Genomic mosaicism describes the phenomenon where some but not all cells within a tissue harbor unique genetic mutations. Traditionally, research focused on the impact of genomic mosaicism on clinical phenotype-motivated by its involvement in cancers and overgrowth syndromes. More recently, we increasingly shifted towards the plethora of neutral mosaic variants that can act as recorders of cellular lineage and environmental exposures. Here, we summarize the current state of the field of genomic mosaicism research with a special emphasis on our current understanding of this phenomenon in brain development and homeostasis. Although the field of genomic mosaicism has a rich history, technological advances in the last decade have changed our approaches and greatly improved our knowledge. We will provide current definitions and an overview of contemporary detection approaches for genomic mosaicism. Finally, we will discuss the impact and utility of genomic mosaicism.
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Affiliation(s)
- Jared H Graham
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado School of Medicine, Aurora, 80045-2581, CO, USA
| | - Johannes C M Schlachetzki
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, 92093-0021, San Diego, CA, USA
| | - Xiaoxu Yang
- Department of Neurosciences, University of California San Diego, La Jolla, 92093-0021, San Diego, CA, USA
- Rady Children's Institute for Genomic Medicine, San Diego, 92123, CA, USA
| | - Martin W Breuss
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado School of Medicine, Aurora, 80045-2581, CO, USA.
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4
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Garambois C, Boulesteix M, Fablet M. Effects of Arboviral Infections on Transposable Element Transcript Levels in Aedes aegypti. Genome Biol Evol 2024; 16:evae092. [PMID: 38695057 PMCID: PMC11110940 DOI: 10.1093/gbe/evae092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2024] [Indexed: 05/23/2024] Open
Abstract
Transposable elements are mobile repeated sequences found in all genomes. Transposable elements are controlled by RNA interference pathways in most organisms, and this control involves the PIWI-interacting RNA pathway and the small interfering RNA pathway, which is also known to be the first line of antiviral defense in invertebrates. Using Drosophila, we recently showed that viral infections result in the modulation of transposable element transcript levels through modulation of the small RNA repertoire. The Aedes aegypti mosquito is of particular interest because almost half of its genome is made of transposable elements, and it is described as a major vector of viruses (such as the dengue [DENV], Zika [ZIKV], and chikungunya [CHIKV] arboviruses). Moreover, Aedes mosquitoes are unique among insects in that the PIWI-interacting RNA pathway is also involved in the somatic antiviral response, in addition to the transposable element control and PIWI-interacting RNA pathway genes expanded in the mosquito genome. For these reasons, we studied the impacts of viral infections on transposable element transcript levels in A. aegypti samples. We retrieved public datasets corresponding to RNA-seq data obtained from viral infections by DENV, ZIKV, and CHIKV in various tissues. We found that transposable element transcripts are moderately modulated following viral infection and that the direction of the modulation varies greatly across tissues and viruses. These results highlight the need for an in-depth investigation of the tightly intertwined interactions between transposable elements and viruses.
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Affiliation(s)
- Chloé Garambois
- Universite Claude Bernard Lyon 1, Laboratoire de Biométrie et Biologie Evolutive (LBBE), UMR 5558, CNRS, VAS, Villeurbanne 69622, France
| | - Matthieu Boulesteix
- Universite Claude Bernard Lyon 1, Laboratoire de Biométrie et Biologie Evolutive (LBBE), UMR 5558, CNRS, VAS, Villeurbanne 69622, France
| | - Marie Fablet
- Universite Claude Bernard Lyon 1, Laboratoire de Biométrie et Biologie Evolutive (LBBE), UMR 5558, CNRS, VAS, Villeurbanne 69622, France
- Institut Universitaire de France (IUF), Paris, France
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5
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Beletskiy A, Zolotar A, Fortygina P, Chesnokova E, Uroshlev L, Balaban P, Kolosov P. Downregulation of Ribosomal Protein Genes Is Revealed in a Model of Rat Hippocampal Neuronal Culture Activation with GABA(A)R/GlyRa2 Antagonist Picrotoxin. Cells 2024; 13:383. [PMID: 38474347 DOI: 10.3390/cells13050383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 02/13/2024] [Accepted: 02/20/2024] [Indexed: 03/14/2024] Open
Abstract
Long-read transcriptome sequencing provides us with a convenient tool for the thorough study of biological processes such as neuronal plasticity. Here, we aimed to perform transcriptional profiling of rat hippocampal primary neuron cultures after stimulation with picrotoxin (PTX) to further understand molecular mechanisms of neuronal activation. To overcome the limitations of short-read RNA-Seq approaches, we performed an Oxford Nanopore Technologies MinION-based long-read sequencing and transcriptome assembly of rat primary hippocampal culture mRNA at three time points after the PTX activation. We used a specific approach to exclude uncapped mRNAs during sample preparation. Overall, we found 23,652 novel transcripts in comparison to reference annotations, out of which ~6000 were entirely novel and mostly transposon-derived loci. Analysis of differentially expressed genes (DEG) showed that 3046 genes were differentially expressed, of which 2037 were upregulated and 1009 were downregulated at 30 min after the PTX application, with only 446 and 13 genes differentially expressed at 1 h and 5 h time points, respectively. Most notably, multiple genes encoding ribosomal proteins, with a high basal expression level, were downregulated after 30 min incubation with PTX; we suggest that this indicates redistribution of transcriptional resources towards activity-induced genes. Novel loci and isoforms observed in this study may help us further understand the functional mRNA repertoire in neuronal plasticity processes. Together with other NGS techniques, differential gene expression analysis of sequencing data obtained using MinION platform might provide a simple method to optimize further study of neuronal plasticity.
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Affiliation(s)
- Alexander Beletskiy
- Institute of Higher Nervous Activity and Neurophysiology, The Russian Academy of Sciences, 117485 Moscow, Russia
| | - Anastasia Zolotar
- Institute of Higher Nervous Activity and Neurophysiology, The Russian Academy of Sciences, 117485 Moscow, Russia
| | - Polina Fortygina
- Institute of Higher Nervous Activity and Neurophysiology, The Russian Academy of Sciences, 117485 Moscow, Russia
| | - Ekaterina Chesnokova
- Institute of Higher Nervous Activity and Neurophysiology, The Russian Academy of Sciences, 117485 Moscow, Russia
| | - Leonid Uroshlev
- Institute of Higher Nervous Activity and Neurophysiology, The Russian Academy of Sciences, 117485 Moscow, Russia
| | - Pavel Balaban
- Institute of Higher Nervous Activity and Neurophysiology, The Russian Academy of Sciences, 117485 Moscow, Russia
| | - Peter Kolosov
- Institute of Higher Nervous Activity and Neurophysiology, The Russian Academy of Sciences, 117485 Moscow, Russia
- Engelhardt Institute of Molecular Biology, The Russian Academy of Sciences, 119991 Moscow, Russia
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6
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Lu X, Liu L. Genome stability from the perspective of telomere length. Trends Genet 2024; 40:175-186. [PMID: 37957036 DOI: 10.1016/j.tig.2023.10.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023]
Abstract
Telomeres and their associated proteins protect the ends of chromosomes to maintain genome stability. Telomeres undergo progressive shortening with each cell division in mammalian somatic cells without telomerase, resulting in genome instability. When telomeres reach a critically short length or are recognized as a damage signal, cells enter a state of senescence, followed by cell cycle arrest, programmed cell death, or immortalization. This review provides an overview of recent advances in the intricate relationship between telomeres and genome instability. Alongside well-established mechanisms such as chromosomal fusion and telomere fusion, we will delve into the perspective on genome stability by examining the role of retrotransposons. Retrotransposons represent an emerging pathway to regulate genome stability through their interactions with telomeres.
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Affiliation(s)
- Xinyi Lu
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, Tianjin 300350, China.
| | - Lin Liu
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, Tianjin 300350, China; Frontiers Science Center for Cell Responses, College of Life Science, Nankai University, Tianjin, Tianjin 300071, China; Haihe Laboratory of Cell Ecosystem, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300020, China; Institute of Translational Medicine, Tianjin Union Medical Center, Nankai University, Tianjin 300000, China.
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7
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Luqman-Fatah A, Miyoshi T. Human LINE-1 retrotransposons: impacts on the genome and regulation by host factors. Genes Genet Syst 2023; 98:121-154. [PMID: 36436935 DOI: 10.1266/ggs.22-00038] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Genome sequencing revealed that nearly half of the human genome is comprised of transposable elements. Although most of these elements have been rendered inactive due to mutations, full-length intact long interspersed element-1 (LINE-1 or L1) copies retain the ability to mobilize through RNA intermediates by a so-called "copy-and-paste" mechanism, termed retrotransposition. L1 is the only known autonomous mobile genetic element in the genome, and its retrotransposition contributes to inter- or intra-individual genetic variation within the human population. However, L1 retrotransposition also poses a threat to genome integrity due to gene disruption and chromosomal instability. Moreover, recent studies suggest that aberrant L1 expression can impact human health by causing diseases such as cancer and chronic inflammation that might lead to autoimmune disorders. To counteract these adverse effects, the host cells have evolved multiple layers of defense mechanisms at the epigenetic, RNA and protein levels. Intriguingly, several host factors have also been reported to facilitate L1 retrotransposition, suggesting that there is competition between negative and positive regulation of L1 by host factors. Here, we summarize the known host proteins that regulate L1 activity at different stages of the replication cycle and discuss how these factors modulate disease-associated phenotypes caused by L1.
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Affiliation(s)
- Ahmad Luqman-Fatah
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University
- Department of Stress Response, Radiation Biology Center, Graduate School of Biostudies, Kyoto University
| | - Tomoichiro Miyoshi
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University
- Department of Stress Response, Radiation Biology Center, Graduate School of Biostudies, Kyoto University
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8
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Lindehell H, Schwartz YB, Larsson J. Methylation of lysine 36 on histone H3 is required to control transposon activities in somatic cells. Life Sci Alliance 2023; 6:e202201832. [PMID: 37169594 PMCID: PMC10176111 DOI: 10.26508/lsa.202201832] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 05/03/2023] [Accepted: 05/03/2023] [Indexed: 05/13/2023] Open
Abstract
Transposable elements constitute a substantial portion of most eukaryotic genomes and their activity can lead to developmental and neuronal defects. In the germline, transposon activity is antagonized by the PIWI-interacting RNA pathway tasked with repression of transposon transcription and degrading transcripts that have already been produced. However, most of the genes required for transposon control are not expressed outside the germline, prompting the question: what causes deleterious transposons activity in the soma and how is it managed? Here, we show that disruptions of the Histone 3 lysine 36 methylation machinery led to increased transposon transcription in Drosophila melanogaster brains and that there is division of labour for the repression of transposable elements between the different methyltransferases Set2, NSD, and Ash1. Furthermore, we show that disruption of methylation leads to somatic activation of key genes in the PIWI-interacting RNA pathway and the preferential production of RNA from dual-strand piRNA clusters.
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Affiliation(s)
| | - Yuri B Schwartz
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Jan Larsson
- Department of Molecular Biology, Umeå University, Umeå, Sweden
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9
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Contribution of Retrotransposons to the Pathogenesis of Type 1 Diabetes and Challenges in Analysis Methods. Int J Mol Sci 2023; 24:ijms24043104. [PMID: 36834511 PMCID: PMC9966460 DOI: 10.3390/ijms24043104] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/09/2023] Open
Abstract
Type 1 diabetes (T1D) is one of the most common chronic diseases of the endocrine system, associated with several life-threatening comorbidities. While the etiopathogenesis of T1D remains elusive, a combination of genetic susceptibility and environmental factors, such as microbial infections, are thought to be involved in the development of the disease. The prime model for studying the genetic component of T1D predisposition encompasses polymorphisms within the HLA (human leukocyte antigen) region responsible for the specificity of antigen presentation to lymphocytes. Apart from polymorphisms, genomic reorganization caused by repeat elements and endogenous viral elements (EVEs) might be involved in T1D predisposition. Such elements are human endogenous retroviruses (HERVs) and non-long terminal repeat (non-LTR) retrotransposons, including long and short interspersed nuclear elements (LINEs and SINEs). In line with their parasitic origin and selfish behaviour, retrotransposon-imposed gene regulation is a major source of genetic variation and instability in the human genome, and may represent the missing link between genetic susceptibility and environmental factors long thought to contribute to T1D onset. Autoreactive immune cell subtypes with differentially expressed retrotransposons can be identified with single-cell transcriptomics, and personalized assembled genomes can be constructed, which can then serve as a reference for predicting retrotransposon integration/restriction sites. Here we review what is known to date about retrotransposons, we discuss the involvement of viruses and retrotransposons in T1D predisposition, and finally we consider challenges in retrotransposons analysis methods.
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10
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Potential health risks of mRNA-based vaccine therapy: A hypothesis. Med Hypotheses 2023; 171:111015. [PMID: 36718314 PMCID: PMC9876036 DOI: 10.1016/j.mehy.2023.111015] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 09/08/2022] [Accepted: 01/24/2023] [Indexed: 01/26/2023]
Abstract
Therapeutic applications of synthetic mRNA were proposed more than 30 years ago, and are currently the basis of one of the vaccine platforms used at a massive scale as part of the public health strategy to get COVID-19 under control. To date, there are no published studies on the biodistribution, cellular uptake, endosomal escape, translation rates, functional half-life and inactivation kinetics of synthetic mRNA, rates and duration of vaccine-induced antigen expression in different cell types. Furthermore, despite the assumption that there is no possibility of genomic integration of therapeutic synthetic mRNA, only one recent study has examined interactions between vaccine mRNA and the genome of transfected cells, and reported that an endogenous retrotransposon, LINE-1 is unsilenced following mRNA entry to the cell, leading to reverse transcription of full length vaccine mRNA sequences, and nuclear entry. This finding should be a major safety concern, given the possibility of synthetic mRNA-driven epigenetic and genomic modifications arising. We propose that in susceptible individuals, cytosolic clearance of nucleotide modified synthetic (nms-mRNAs) is impeded. Sustained presence of nms-mRNA in the cytoplasm deregulates and activates endogenous transposable elements (TEs), causing some of the mRNA copies to be reverse transcribed. The cytosolic accumulation of the nms-mRNA and the reverse transcribed cDNA molecules activates RNA and DNA sensory pathways. Their concurrent activation initiates a synchronized innate response against non-self nucleic acids, prompting type-I interferon and pro-inflammatory cytokine production which, if unregulated, leads to autoinflammatory and autoimmune conditions, while activated TEs increase the risk of insertional mutagenesis of the reverse transcribed molecules, which can disrupt coding regions, enhance the risk of mutations in tumour suppressor genes, and lead to sustained DNA damage. Susceptible individuals would then expectedly have an increased risk of DNA damage, chronic autoinflammation, autoimmunity and cancer. In light of the current mass administration of nms-mRNA vaccines, it is essential and urgent to fully understand the intracellular cascades initiated by cellular uptake of synthetic mRNA and the consequences of these molecular events.
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11
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Warkocki Z. An update on post-transcriptional regulation of retrotransposons. FEBS Lett 2023; 597:380-406. [PMID: 36460901 DOI: 10.1002/1873-3468.14551] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 11/09/2022] [Accepted: 11/18/2022] [Indexed: 12/04/2022]
Abstract
Retrotransposons, including LINE-1, Alu, SVA, and endogenous retroviruses, are one of the major constituents of human genomic repetitive sequences. Through the process of retrotransposition, some of them occasionally insert into new genomic locations by a copy-paste mechanism involving RNA intermediates. Irrespective of de novo genomic insertions, retrotransposon expression can lead to DNA double-strand breaks and stimulate cellular innate immunity through endogenous patterns. As a result, retrotransposons are tightly regulated by multi-layered regulatory processes to prevent the dangerous effects of their expression. In recent years, significant progress was made in revealing how retrotransposon biology intertwines with general post-transcriptional RNA metabolism. Here, I summarize current knowledge on the involvement of post-transcriptional factors in the biology of retrotransposons, focusing on LINE-1. I emphasize general RNA metabolisms such as methylation of adenine (m6 A), RNA 3'-end polyadenylation and uridylation, RNA decay and translation regulation. I discuss the effects of retrotransposon RNP sequestration in cytoplasmic bodies and autophagy. Finally, I summarize how innate immunity restricts retrotransposons and how retrotransposons make use of cellular enzymes, including the DNA repair machinery, to complete their replication cycles.
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Affiliation(s)
- Zbigniew Warkocki
- Department of RNA Metabolism, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
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12
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Ahn HW, Worman ZF, Lechsinska A, Payer LM, Wang T, Malik N, Li W, Burns KH, Nath A, Levin HL. Retrotransposon insertions associated with risk of neurologic and psychiatric diseases. EMBO Rep 2023; 24:e55197. [PMID: 36367221 PMCID: PMC9827563 DOI: 10.15252/embr.202255197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 10/11/2022] [Accepted: 10/20/2022] [Indexed: 11/13/2022] Open
Abstract
Transposable elements (TEs) are active in neuronal cells raising the question whether TE insertions contribute to risk of neuropsychiatric disease. While genome-wide association studies (GWAS) serve as a tool to discover genetic loci associated with neuropsychiatric diseases, unfortunately GWAS do not directly detect structural variants such as TEs. To examine the role of TEs in psychiatric and neurologic disease, we evaluated 17,000 polymorphic TEs and find 76 are in linkage disequilibrium with disease haplotypes (P < 10-6 ) defined by GWAS. From these 76 polymorphic TEs, we identify potentially causal candidates based on having insertions in genomic regions of regulatory chromatin and on having associations with altered gene expression in brain tissues. We show that lead candidate insertions have regulatory effects on gene expression in human neural stem cells altering the activity of a minimal promoter. Taken together, we identify 10 polymorphic TE insertions that are potential candidates on par with other variants for having a causal role in neurologic and psychiatric disorders.
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Affiliation(s)
- Hyo Won Ahn
- Division of Molecular and Cellular BiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of HealthBethesdaMDUSA
| | - Zelia F Worman
- Division of Molecular and Cellular BiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of HealthBethesdaMDUSA
- Present address:
Seven BridgesCharlestownMAUSA
| | - Arianna Lechsinska
- Division of Molecular and Cellular BiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of HealthBethesdaMDUSA
| | - Lindsay M Payer
- Department of PathologyJohns Hopkins University School of MedicineBaltimoreMDUSA
| | - Tongguang Wang
- Translational Neuroscience CenterNational Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaMDUSA
| | - Nasir Malik
- Translational Neuroscience CenterNational Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaMDUSA
| | - Wenxue Li
- Section of Infections of the Nervous SystemNational Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaMDUSA
| | - Kathleen H Burns
- Department of Oncologic PathologyDana‐Farber Cancer InstituteBostonMAUSA
| | - Avindra Nath
- Translational Neuroscience CenterNational Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaMDUSA
- Section of Infections of the Nervous SystemNational Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaMDUSA
| | - Henry L Levin
- Division of Molecular and Cellular BiologyEunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of HealthBethesdaMDUSA
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13
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Abstract
By silencing L1 retrotransposons, DNA methylation protects mammalian genomes from potent endogenous mutagens. However, some loci can escape this repressive mechanism and become active, particularly in carcinomas. Alterations of L1 DNA methylation can also locally influence gene expression. Comprehensive measurement of L1 DNA methylation at the locus level remains challenging. Here, we present bs-ATLAS-seq, a genome-wide approach to locate full-length L1 elements in the human genome, and assess their methylation levels at single-base and single-locus resolutions. This strategy targets the youngest, and only retrotransposition-competent family, L1HS, but also detects a significant fraction of older elements (L1PA2 to L1PA8). Bs-ATLAS-seq evaluates methylation at the first 15 CpGs of L1 5' UTR, which corresponds to the first half of the sense promoter. It relies on random fragmentation of the genomic DNA, adapter ligation, bisulfite treatment and suppression PCR, and ends by asymmetrical paired-end sequencing. A dedicated pipeline provides the location of L1 elements and their methylation status, including for non-reference loci, as well as their single-molecule DNA profiles.
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14
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Garcia-Cañadas M, Sanchez-Luque FJ, Sanchez L, Rojas J, Garcia Perez JL. LINE-1 Retrotransposition Assays in Embryonic Stem Cells. Methods Mol Biol 2023; 2607:257-309. [PMID: 36449167 DOI: 10.1007/978-1-0716-2883-6_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The ongoing mobilization of active non-long terminal repeat (LTR) retrotransposons continues to impact the genomes of most mammals, including humans and rodents. Non-LTR retrotransposons mobilize using an intermediary RNA and a copy-and-paste mechanism termed retrotransposition. Non-LTR retrotransposons are subdivided into long and short interspersed elements (LINEs and SINEs, respectively), depending on their size and autonomy; while active class 1 LINEs (LINE-1s or L1s) encode the enzymatic machinery required to mobilize in cis, active SINEs use the enzymatic machinery of active LINE-1s to mobilize in trans. The mobilization mechanism used by LINE-1s/SINEs was exploited to develop ingenious plasmid-based retrotransposition assays in cultured cells, which typically exploit a reporter gene that can only be activated after a round of retrotransposition. Retrotransposition assays, in cis or in trans, are instrumental tools to study the biology of mammalian LINE-1s and SINEs. In fact, these and other biochemical/genetic assays were used to uncover that endogenous mammalian LINE-1s/SINEs naturally retrotranspose during early embryonic development. However, embryonic stem cells (ESCs) are typically used as a cellular model in these and other studies interrogating LINE-1/SINE expression/regulation during early embryogenesis. Thus, human and mouse ESCs represent an excellent model to understand how active retrotransposons are regulated and how their activity impacts the germline. Here, we describe robust and quantitative protocols to study human/mouse LINE-1 (in cis) and SINE (in trans) retrotransposition using (human and mice) ESCs. These protocols are designed to study the mobilization of active non-LTR retrotransposons in a cellular physiologically relevant context.
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Affiliation(s)
- Marta Garcia-Cañadas
- Pfizer-University of Granada-Andalusian Government Centre for Genomics and Oncological Research (GENYO), PTS Granada, Granada, Spain.
| | - Francisco J Sanchez-Luque
- Institute of Parasitology and Biomedicine "Lopez-Neyra" (IPBLN), Spanish National Research Council (CSIC), PTS Granada, Granada, Spain
| | - Laura Sanchez
- Pfizer-University of Granada-Andalusian Government Centre for Genomics and Oncological Research (GENYO), PTS Granada, Granada, Spain
| | - Johana Rojas
- Pfizer-University of Granada-Andalusian Government Centre for Genomics and Oncological Research (GENYO), PTS Granada, Granada, Spain
| | - Jose L Garcia Perez
- Pfizer-University of Granada-Andalusian Government Centre for Genomics and Oncological Research (GENYO), PTS Granada, Granada, Spain.
- MRC Human Genetics Unit, Institute of Genetics and Cancer (IGC)/University of Edinburgh, Western General Hospital Campus, Edinburgh, UK.
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15
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Smits N, Faulkner GJ. Nanopore Sequencing to Identify Transposable Element Insertions and Their Epigenetic Modifications. Methods Mol Biol 2023; 2607:151-171. [PMID: 36449163 DOI: 10.1007/978-1-0716-2883-6_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Over the past 20 years, high-throughput genomic assays have fundamentally changed how transposable elements (TEs) are studied. While short-read DNA sequencing has been at the heart of these efforts, novel technologies that generate longer reads are driving a shift in the field. Long-read sequencing now permits locus-specific approaches to locate individual TE insertions and understand their epigenetic and transcriptional regulation, while still profiling TE activity genome-wide. Here we provide detailed guidelines to implement Oxford Nanopore Technologies (ONT) sequencing to identify polymorphic TE insertions and profile TE epigenetic landscapes. Using human long interspersed element-1 (LINE-1, L1) as an example, we explain the procedures involved, including final visualization, and potential bottlenecks and pitfalls. ONT sequencing will be, in our view, a workhorse technology for the foreseeable future in the TE field.
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Affiliation(s)
- Nathan Smits
- Mater Research Institute, University of Queensland, Woolloongabba, QLD, Australia
| | - Geoffrey J Faulkner
- Mater Research Institute, University of Queensland, Woolloongabba, QLD, Australia.
- Queensland Brain Institute, University of Queensland, Brisbane, QLD, Australia.
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16
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Lee H, Min JW, Mun S, Han K. Human Retrotransposons and Effective Computational Detection Methods for Next-Generation Sequencing Data. LIFE (BASEL, SWITZERLAND) 2022; 12:life12101583. [PMID: 36295018 PMCID: PMC9605557 DOI: 10.3390/life12101583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/03/2022] [Accepted: 10/10/2022] [Indexed: 11/16/2022]
Abstract
Transposable elements (TEs) are classified into two classes according to their mobilization mechanism. Compared to DNA transposons that move by the "cut and paste" mechanism, retrotransposons mobilize via the "copy and paste" method. They have been an essential research topic because some of the active elements, such as Long interspersed element 1 (LINE-1), Alu, and SVA elements, have contributed to the genetic diversity of primates beyond humans. In addition, they can cause genetic disorders by altering gene expression and generating structural variations (SVs). The development and rapid technological advances in next-generation sequencing (NGS) have led to new perspectives on detecting retrotransposon-mediated SVs, especially insertions. Moreover, various computational methods have been developed based on NGS data to precisely detect the insertions and deletions in the human genome. Therefore, this review discusses details about the recently studied and utilized NGS technologies and the effective computational approaches for discovering retrotransposons through it. The final part covers a diverse range of computational methods for detecting retrotransposon insertions with human NGS data. This review will give researchers insights into understanding the TEs and how to investigate them and find connections with research interests.
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Affiliation(s)
- Haeun Lee
- Department of Bioconvergence Engineering, Dankook University, Yongin 16890, Korea
| | - Jun Won Min
- Department of Surgery, Dankook University College of Medicine, Cheonan 31116, Korea
| | - Seyoung Mun
- Department of Microbiology, College of Science & Technology, Dankook University, Cheonan 31116, Korea
- Center for Bio Medical Engineering Core Facility, Dankook University, Cheonan 31116, Korea
- Correspondence: (S.M.); (K.H.)
| | - Kyudong Han
- Department of Bioconvergence Engineering, Dankook University, Yongin 16890, Korea
- Department of Microbiology, College of Science & Technology, Dankook University, Cheonan 31116, Korea
- Center for Bio Medical Engineering Core Facility, Dankook University, Cheonan 31116, Korea
- HuNbiome Co., Ltd., R&D Center, Seoul 08507, Korea
- Correspondence: (S.M.); (K.H.)
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17
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Stekelenburg C, Blouin JL, Santoni F, Zaghloul N, O'Hare EA, Dusaulcy R, Maechler P, Schwitzgebel VM. Loss of Nexmif results in the expression of phenotypic variability and loss of genomic integrity. Sci Rep 2022; 12:13815. [PMID: 35970867 PMCID: PMC9378738 DOI: 10.1038/s41598-022-17845-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 08/02/2022] [Indexed: 11/17/2022] Open
Abstract
We identified two NEXMIF variants in two unrelated individuals with non-autoimmune diabetes and autistic traits, and investigated the expression of Nexmif in mouse and human pancreas and its function in pancreatic beta cells in vitro and in vivo. In insulin-secreting INS-1E cells, Nexmif expression increased strongly in response to oxidative stress. CRISPR Cas9-generated Nexmif knockout mice exhibited a reduced number of proliferating beta cells in pancreatic islets. RNA sequencing of pancreatic islets showed that the downregulated genes in Nexmif mutant islets are involved in stress response and the deposition of epigenetic marks. They include H3f3b, encoding histone H3.3, which is associated with the regulation of beta-cell proliferation and maintains genomic integrity by silencing transposable elements, particularly LINE1 elements. LINE1 activity has been associated with autism and neurodevelopmental disorders in which patients share characteristics with NEXMIF patients, and can cause genomic instability and genetic variation through retrotransposition. Nexmif knockout mice exhibited various other phenotypes. Mortality and phenotypic abnormalities increased in each generation in both Nexmif mutant and non-mutant littermates. In Nexmif mutant mice, LINE1 element expression was upregulated in the pancreas, brain, and testis, possibly inducing genomic instability in Nexmif mutant mice and causing phenotypic variability in their progeny.
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Affiliation(s)
- Caroline Stekelenburg
- Pediatric Endocrine and Diabetes Unit, Division of Development and Growth, Department of Pediatrics, Gynecology and Obstetrics, University Hospitals of Geneva, Children's University Hospital, 6, Rue Willy Donze, 1205, Geneva, Switzerland.,Faculty Diabetes Center, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Jean-Louis Blouin
- Department of Genetic Medicine and Laboratory, University Hospitals of Geneva, 1211, Geneva, Switzerland.,Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, 1211, Geneva, Switzerland
| | - Federico Santoni
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, 1211, Geneva, Switzerland
| | - Norann Zaghloul
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, USA
| | - Elisabeth A O'Hare
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, USA
| | - Rodolphe Dusaulcy
- Pediatric Endocrine and Diabetes Unit, Division of Development and Growth, Department of Pediatrics, Gynecology and Obstetrics, University Hospitals of Geneva, Children's University Hospital, 6, Rue Willy Donze, 1205, Geneva, Switzerland.,Faculty Diabetes Center, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Pierre Maechler
- Faculty Diabetes Center, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Department of Cell Physiology and Metabolism, University of Geneva Medical Center, 1206, Geneva, Switzerland
| | - Valerie M Schwitzgebel
- Pediatric Endocrine and Diabetes Unit, Division of Development and Growth, Department of Pediatrics, Gynecology and Obstetrics, University Hospitals of Geneva, Children's University Hospital, 6, Rue Willy Donze, 1205, Geneva, Switzerland. .,Faculty Diabetes Center, Faculty of Medicine, University of Geneva, Geneva, Switzerland.
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18
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Vujovic F, Hunter N, Farahani RM. Cellular self-organization: An overdrive in Cambrian diversity? Bioessays 2022; 44:e2200033. [PMID: 35900058 DOI: 10.1002/bies.202200033] [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: 02/05/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 11/10/2022]
Abstract
During the early Cambrian period metazoan life forms diverged at an accelerated rate to occupy multiple ecological niches on earth. A variety of explanations have been proposed to address this major evolutionary phenomenon termed the "Cambrian explosion." While most hypotheses address environmental, developmental, and ecological factors that facilitated evolutionary innovations, the biological basis for accelerated emergence of species diversity in the Cambrian period remains largely conjectural. Herein, we posit that morphogenesis by self-organization enables the uncoupling of genomic mutational landscape from phenotypic diversification. Evidence is provided for a two-tiered interpretation of genomic changes in metazoan animals wherein mutations not only impact upon function of individual cells, but also alter the self-organization outcome during developmental morphogenesis. We provide evidence that the morphological impacts of mutations on self-organization could remain repressed if associated with an unmet negative energetic cost. We posit that accelerated morphological diversification in transition to the Cambrian period has occurred by emergence of dormant (i.e., reserved) morphological novelties whose molecular underpinnings were seeded in the Precambrian period.
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Affiliation(s)
- Filip Vujovic
- IDR/Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Neil Hunter
- IDR/Westmead Institute for Medical Research, Sydney, New South Wales, Australia
| | - Ramin M Farahani
- IDR/Westmead Institute for Medical Research, Sydney, New South Wales, Australia.,School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
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19
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Billon V, Sanchez-Luque FJ, Rasmussen J, Bodea GO, Gerhardt DJ, Gerdes P, Cheetham SW, Schauer SN, Ajjikuttira P, Meyer TJ, Layman CE, Nevonen KA, Jansz N, Garcia-Perez JL, Richardson SR, Ewing AD, Carbone L, Faulkner GJ. Somatic retrotransposition in the developing rhesus macaque brain. Genome Res 2022; 32:1298-1314. [PMID: 35728967 PMCID: PMC9341517 DOI: 10.1101/gr.276451.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/14/2022] [Indexed: 12/03/2022]
Abstract
The retrotransposon LINE-1 (L1) is central to the recent evolutionary history of the human genome and continues to drive genetic diversity and germline pathogenesis. However, the spatiotemporal extent and biological significance of somatic L1 activity are poorly defined and are virtually unexplored in other primates. From a single L1 lineage active at the divergence of apes and Old World monkeys, successive L1 subfamilies have emerged in each descendant primate germline. As revealed by case studies, the presently active human L1 subfamily can also mobilize during embryonic and brain development in vivo. It is unknown whether nonhuman primate L1s can similarly generate somatic insertions in the brain. Here we applied approximately 40× single-cell whole-genome sequencing (scWGS), as well as retrotransposon capture sequencing (RC-seq), to 20 hippocampal neurons from two rhesus macaques (Macaca mulatta). In one animal, we detected and PCR-validated a somatic L1 insertion that generated target site duplications, carried a short 5′ transduction, and was present in ∼7% of hippocampal neurons but absent from cerebellum and nonbrain tissues. The corresponding donor L1 allele was exceptionally mobile in vitro and was embedded in PRDM4, a gene expressed throughout development and in neural stem cells. Nanopore long-read methylome and RNA-seq transcriptome analyses indicated young retrotransposon subfamily activation in the early embryo, followed by repression in adult tissues. These data highlight endogenous macaque L1 retrotransposition potential, provide prototypical evidence of L1-mediated somatic mosaicism in a nonhuman primate, and allude to L1 mobility in the brain over the past 30 million years of human evolution.
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20
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The Role of Transposable Elements of the Human Genome in Neuronal Function and Pathology. Int J Mol Sci 2022; 23:ijms23105847. [PMID: 35628657 PMCID: PMC9148063 DOI: 10.3390/ijms23105847] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [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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21
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A retrotransposon storm marks clinical phenoconversion to late-onset Alzheimer's disease. GeroScience 2022; 44:1525-1550. [PMID: 35585302 PMCID: PMC9213607 DOI: 10.1007/s11357-022-00580-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 04/26/2022] [Indexed: 12/03/2022] Open
Abstract
Recent reports have suggested that the reactivation of otherwise transcriptionally silent transposable elements (TEs) might induce brain degeneration, either by dysregulating the expression of genes and pathways implicated in cognitive decline and dementia or through the induction of immune-mediated neuroinflammation resulting in the elimination of neural and glial cells. In the work we present here, we test the hypothesis that differentially expressed TEs in blood could be used as biomarkers of cognitive decline and development of AD. To this aim, we used a sample of aging subjects (age > 70) that developed late-onset Alzheimer’s disease (LOAD) over a relatively short period of time (12–48 months), for which blood was available before and after their phenoconversion, and a group of cognitive stable subjects as controls. We applied our developed and validated customized pipeline that allows the identification, characterization, and quantification of the differentially expressed (DE) TEs before and after the onset of manifest LOAD, through analyses of RNA-Seq data. We compared the level of DE TEs within more than 600,000 TE-mapping RNA transcripts from 25 individuals, whose specimens we obtained before and after their phenotypic conversion (phenoconversion) to LOAD, and discovered that 1790 TE transcripts showed significant expression differences between these two timepoints (logFC ± 1.5, logCMP > 5.3, nominal p value < 0.01). These DE transcripts mapped both over- and under-expressed TE elements. Occurring before the clinical phenoconversion, this TE storm features significant increases in DE transcripts of LINEs, LTRs, and SVAs, while those for SINEs are significantly depleted. These dysregulations end with signs of manifest LOAD. This set of highly DE transcripts generates a TE transcriptional profile that accurately discriminates the before and after phenoconversion states of these subjects. Our findings suggest that a storm of DE TEs occurs before phenoconversion from normal cognition to manifest LOAD in risk individuals compared to controls, and may provide useful blood-based biomarkers for heralding such a clinical transition, also suggesting that TEs can indeed participate in the complex process of neurodegeneration.
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22
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Campitelli LF, Yellan I, Albu M, Barazandeh M, Patel ZM, Blanchette M, Hughes TR. Reconstruction of full-length LINE-1 progenitors from ancestral genomes. Genetics 2022; 221:6584822. [PMID: 35552404 PMCID: PMC9252281 DOI: 10.1093/genetics/iyac074] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/27/2022] [Indexed: 11/24/2022] Open
Abstract
Sequences derived from the Long INterspersed Element-1 (L1) family of retrotransposons occupy at least 17% of the human genome, with 67 distinct subfamilies representing successive waves of expansion and extinction in mammalian lineages. L1s contribute extensively to gene regulation, but their molecular history is difficult to trace, because most are present only as truncated and highly mutated fossils. Consequently, L1 entries in current databases of repeat sequences are composed mainly of short diagnostic subsequences, rather than full functional progenitor sequences for each subfamily. Here, we have coupled 2 levels of sequence reconstruction (at the level of whole genomes and L1 subfamilies) to reconstruct progenitor sequences for all human L1 subfamilies that are more functionally and phylogenetically plausible than existing models. Most of the reconstructed sequences are at or near the canonical length of L1s and encode uninterrupted ORFs with expected protein domains. We also show that the presence or absence of binding sites for KRAB-C2H2 Zinc Finger Proteins, even in ancient-reconstructed progenitor L1s, mirrors binding observed in human ChIP-exo experiments, thus extending the arms race and domestication model. RepeatMasker searches of the modern human genome suggest that the new models may be able to assign subfamily resolution identities to previously ambiguous L1 instances. The reconstructed L1 sequences will be useful for genome annotation and functional study of both L1 evolution and L1 contributions to host regulatory networks.
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Affiliation(s)
- Laura F Campitelli
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada.,Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Isaac Yellan
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada.,Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Mihai Albu
- Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Marjan Barazandeh
- Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada.,Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Zain M Patel
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada.,Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Mathieu Blanchette
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.,Department of Computer Science, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Timothy R Hughes
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada.,Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada
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23
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Domazet-Lošo T. mRNA Vaccines: Why Is the Biology of Retroposition Ignored? Genes (Basel) 2022; 13:719. [PMID: 35627104 PMCID: PMC9141755 DOI: 10.3390/genes13050719] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/14/2022] [Accepted: 04/15/2022] [Indexed: 02/07/2023] Open
Abstract
The major advantage of mRNA vaccines over more conventional approaches is their potential for rapid development and large-scale deployment in pandemic situations. In the current COVID-19 crisis, two mRNA COVID-19 vaccines have been conditionally approved and broadly applied, while others are still in clinical trials. However, there is no previous experience with the use of mRNA vaccines on a large scale in the general population. This warrants a careful evaluation of mRNA vaccine safety properties by considering all available knowledge about mRNA molecular biology and evolution. Here, I discuss the pervasive claim that mRNA-based vaccines cannot alter genomes. Surprisingly, this notion is widely stated in the mRNA vaccine literature but never supported by referencing any primary scientific papers that would specifically address this question. This discrepancy becomes even more puzzling if one considers previous work on the molecular and evolutionary aspects of retroposition in murine and human populations that clearly documents the frequent integration of mRNA molecules into genomes, including clinical contexts. By performing basic comparisons, I show that the sequence features of mRNA vaccines meet all known requirements for retroposition using L1 elements-the most abundant autonomously active retrotransposons in the human genome. In fact, many factors associated with mRNA vaccines increase the possibility of their L1-mediated retroposition. I conclude that is unfounded to a priori assume that mRNA-based therapeutics do not impact genomes and that the route to genome integration of vaccine mRNAs via endogenous L1 retroelements is easily conceivable. This implies that we urgently need experimental studies that would rigorously test for the potential retroposition of vaccine mRNAs. At present, the insertional mutagenesis safety of mRNA-based vaccines should be considered unresolved.
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Affiliation(s)
- Tomislav Domazet-Lošo
- Laboratory of Evolutionary Genetics, Division of Molecular Biology, Ruđer Bošković Institute, Bijenička Cesta 54, HR-10000 Zagreb, Croatia;
- School of Medicine, Catholic University of Croatia, Ilica 242, HR-10000 Zagreb, Croatia
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24
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Creamer KM, Larsen EC, Lawrence JB. ZNF146/OZF and ZNF507 target LINE-1 sequences. G3 (BETHESDA, MD.) 2022; 12:jkac002. [PMID: 35100360 PMCID: PMC8896011 DOI: 10.1093/g3journal/jkac002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 12/03/2021] [Indexed: 06/14/2023]
Abstract
Repetitive sequences including transposable elements and transposon-derived fragments account for nearly half of the human genome. While transposition-competent transposable elements must be repressed to maintain genomic stability, mutated and fragmented transposable elements comprising the bulk of repetitive sequences can also contribute to regulation of host gene expression and broader genome organization. Here, we analyzed published ChIP-seq data sets to identify proteins broadly enriched on transposable elements in the human genome. We show 2 of the proteins identified, C2H2 zinc finger-containing proteins ZNF146 (also known as OZF) and ZNF507, are targeted to distinct sites within LINE-1 ORF2 at thousands of locations in the genome. ZNF146 binding sites are found at old and young LINE-1 elements. In contrast, ZNF507 preferentially binds at young LINE-1 sequences correlated to sequence changes in LINE-1 elements at ZNF507's binding site. To gain further insight into ZNF146 and ZNF507 function, we disrupt their expression in HEK293 cells using CRISPR/Cas9 and perform RNA sequencing, finding modest gene expression changes in cells where ZNF507 has been disrupted. We further identify a physical interaction between ZNF507 and PRMT5, suggesting ZNF507 may target arginine methylation activity to LINE-1 sequences.
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Affiliation(s)
- Kevin M Creamer
- Department of Neurology and Pediatrics, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Eric C Larsen
- Department of Neurology and Pediatrics, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Jeanne B Lawrence
- Department of Neurology and Pediatrics, University of Massachusetts Medical School, Worcester, MA 01655, USA
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25
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Dysregulation of Human Somatic piRNA Expression in Parkinson's Disease Subtypes and Stages. Int J Mol Sci 2022; 23:ijms23052469. [PMID: 35269612 PMCID: PMC8910154 DOI: 10.3390/ijms23052469] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 02/14/2022] [Accepted: 02/17/2022] [Indexed: 02/04/2023] Open
Abstract
Piwi interacting RNAs (piRNAs) are small non-coding single-stranded RNA species 20–31 nucleotides in size generated from distinct loci. In germline tissues, piRNAs are amplified via a “ping-pong cycle” to produce secondary piRNAs, which act in transposon silencing. In contrast, the role of somatic-derived piRNAs remains obscure. Here, we investigated the identity and distribution of piRNAs in human somatic tissues to determine their function and potential role in Parkinson’s disease (PD). Human datasets were curated from the Gene Expression Omnibus (GEO) database and a workflow was developed to identify piRNAs, which revealed 902 somatic piRNAs of which 527 were expressed in the brain. These were mainly derived from chromosomes 1, 11, and 19 compared to the germline tissues, which were from 15 and 19. Approximately 20% of somatic piRNAs mapped to transposon 3′ untranslated regions (UTRs), but a large proportion were sensed to the transcript in contrast to germline piRNAs. Gene set enrichment analysis suggested that somatic piRNAs function in neurodegenerative disease. piRNAs undergo dysregulation in different PD subtypes (PD and Parkinson’s disease dementia (PDD)) and stages (premotor and motor). piR-has-92056, piR-hsa-150797, piR-hsa-347751, piR-hsa-1909905, piR-hsa-2476630, and piR-hsa-2834636 from blood small extracellular vesicles were identified as novel biomarkers for PD diagnosis using a sparse partial least square discriminant analysis (sPLS-DA) (accuracy: 92%, AUC = 0.89). This study highlights a role for piRNAs in PD and provides tools for novel biomarker development.
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26
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Peze-Heidsieck E, Bonnifet T, Znaidi R, Ravel-Godreuil C, Massiani-Beaudoin O, Joshi RL, Fuchs J. Retrotransposons as a Source of DNA Damage in Neurodegeneration. Front Aging Neurosci 2022; 13:786897. [PMID: 35058771 PMCID: PMC8764243 DOI: 10.3389/fnagi.2021.786897] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/30/2021] [Indexed: 01/09/2023] Open
Abstract
The etiology of aging-associated neurodegenerative diseases (NDs), such as Parkinson’s disease (PD) and Alzheimer’s disease (AD), still remains elusive and no curative treatment is available. Age is the major risk factor for PD and AD, but the molecular link between aging and neurodegeneration is not fully understood. Aging is defined by several hallmarks, some of which partially overlap with pathways implicated in NDs. Recent evidence suggests that aging-associated epigenetic alterations can lead to the derepression of the LINE-1 (Long Interspersed Element-1) family of transposable elements (TEs) and that this derepression might have important implications in the pathogenesis of NDs. Almost half of the human DNA is composed of repetitive sequences derived from TEs and TE mobility participated in shaping the mammalian genomes during evolution. Although most TEs are mutated and no longer mobile, more than 100 LINE-1 elements have retained their full coding potential in humans and are thus retrotransposition competent. Uncontrolled activation of TEs has now been reported in various models of neurodegeneration and in diseased human brain tissues. We will discuss in this review the potential contribution of LINE-1 elements in inducing DNA damage and genomic instability, which are emerging pathological features in NDs. TEs might represent an important molecular link between aging and neurodegeneration, and a potential target for urgently needed novel therapeutic disease-modifying interventions.
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Affiliation(s)
- Eugenie Peze-Heidsieck
- Center for Interdisciplinary Research in Biology (CIRB), CNRS, INSERM, Collège de France, Université PSL, Paris, France
| | - Tom Bonnifet
- Center for Interdisciplinary Research in Biology (CIRB), CNRS, INSERM, Collège de France, Université PSL, Paris, France
| | - Rania Znaidi
- Center for Interdisciplinary Research in Biology (CIRB), CNRS, INSERM, Collège de France, Université PSL, Paris, France
| | - Camille Ravel-Godreuil
- Center for Interdisciplinary Research in Biology (CIRB), CNRS, INSERM, Collège de France, Université PSL, Paris, France
| | - Olivia Massiani-Beaudoin
- Center for Interdisciplinary Research in Biology (CIRB), CNRS, INSERM, Collège de France, Université PSL, Paris, France
| | - Rajiv L Joshi
- Center for Interdisciplinary Research in Biology (CIRB), CNRS, INSERM, Collège de France, Université PSL, Paris, France
| | - Julia Fuchs
- Center for Interdisciplinary Research in Biology (CIRB), CNRS, INSERM, Collège de France, Université PSL, Paris, France
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27
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Pradhan RK, Ramakrishna W. Transposons: Unexpected players in cancer. Gene 2022; 808:145975. [PMID: 34592349 DOI: 10.1016/j.gene.2021.145975] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 09/19/2021] [Accepted: 09/24/2021] [Indexed: 12/21/2022]
Abstract
Transposons are repetitive DNA sequences encompassing about half of the human genome. They play a vital role in genome stability maintenance and contribute to genomic diversity and evolution. Their activity is regulated by various mechanisms considering the deleterious effects of these mobile elements. Various genetic risk factors and environmental stress conditions affect the regulatory pathways causing alteration of transposon expression. Our knowledge of the biological role of transposons is limited especially in various types of cancers. Retrotransposons of different types (LTR-retrotransposons, LINEs and SINEs) regulate a plethora of genes that have a role in cell reprogramming, tumor suppression, cell cycle, apoptosis, cell adhesion and migration, and DNA repair. The regulatory mechanisms of transposons, their deregulation and different mechanisms underlying transposon-mediated carcinogenesis in humans focusing on the three most prevalent types, lung, breast and colorectal cancers, were reviewed. The modes of regulation employed include alternative splicing, deletion, insertion, duplication in genes and promoters resulting in upregulation, downregulation or silencing of genes.
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28
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Ravel-Godreuil C, Znaidi R, Bonnifet T, Joshi RL, Fuchs J. Transposable elements as new players in neurodegenerative diseases. FEBS Lett 2021; 595:2733-2755. [PMID: 34626428 DOI: 10.1002/1873-3468.14205] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 09/23/2021] [Accepted: 10/03/2021] [Indexed: 01/02/2023]
Abstract
Neurodegenerative diseases (NDs), including the most prevalent Alzheimer's disease and Parkinson disease, share common pathological features. Despite decades of gene-centric approaches, the molecular mechanisms underlying these diseases remain widely elusive. In recent years, transposable elements (TEs), long considered 'junk' DNA, have gained growing interest as pathogenic players in NDs. Age is the major risk factor for most NDs, and several repressive mechanisms of TEs, such as heterochromatinization, fail with age. Indeed, heterochromatin relaxation leading to TE derepression has been reported in various models of neurodegeneration and NDs. There is also evidence that certain pathogenic proteins involved in NDs (e.g., tau, TDP-43) may control the expression of TEs. The deleterious consequences of TE activation are not well known but they could include DNA damage and genomic instability, altered host gene expression, and/or neuroinflammation, which are common hallmarks of neurodegeneration and aging. TEs might thus represent an overlooked pathogenic culprit for both brain aging and neurodegeneration. Certain pathological effects of TEs might be prevented by inhibiting their activity, pointing to TEs as novel targets for neuroprotection.
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Affiliation(s)
- Camille Ravel-Godreuil
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Rania Znaidi
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Tom Bonnifet
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Rajiv L Joshi
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Julia Fuchs
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
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29
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Roy M, Viginier B, Mayeux CA, Ratinier M, Fablet M. Infections by Transovarially Transmitted DMelSV in Drosophila Have No Impact on Ovarian Transposable Element Transcripts but Increase Their Amounts in the Soma. Genome Biol Evol 2021; 13:evab207. [PMID: 34498066 PMCID: PMC8459167 DOI: 10.1093/gbe/evab207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2021] [Indexed: 12/21/2022] Open
Abstract
Transposable elements (TEs) are genomic parasites, which activity is tightly controlled in germline cells. Using Sindbis virus, it was recently demonstrated that viral infections affect TE transcript amounts in somatic tissues. However, the strongest evolutionary impacts are expected in gonads, because that is where the genomes of the next generations lie. Here, we investigated this aspect using the Drosophila melanogaster Sigma virus. It is particularly relevant in the genome/TE interaction given its tropism to ovaries, which is the organ displaying the more sophisticated TE control pathways. Our results in Drosophila simulans flies allowed us to confirm the existence of a strong homeostasis of the TE transcriptome in ovaries upon infection, which, however, rely on TE-derived small RNA modulations. In addition, we performed a meta-analysis of RNA-seq data and propose that the immune pathway that is triggered upon viral infection determines the direction of TE transcript modulation in somatic tissues.
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Affiliation(s)
- Marlène Roy
- Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon 1, CNRS, UMR 5558, Villeurbanne, France
- EPHE, PSL Research University, INRA, Université de Lyon, Université Claude Bernard Lyon1, UMR754, IVPC, Lyon, France
| | - Barbara Viginier
- EPHE, PSL Research University, INRA, Université de Lyon, Université Claude Bernard Lyon1, UMR754, IVPC, Lyon, France
| | - Camille A Mayeux
- Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon 1, CNRS, UMR 5558, Villeurbanne, France
| | - Maxime Ratinier
- EPHE, PSL Research University, INRA, Université de Lyon, Université Claude Bernard Lyon1, UMR754, IVPC, Lyon, France
| | - Marie Fablet
- Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon 1, CNRS, UMR 5558, Villeurbanne, France
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30
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Pham DAT, Le SD, Doan TM, Luu PT, Nguyen UQ, Ho SV, Vo LTT. Standardization of DNA amount for bisulfite conversion for analyzing the methylation status of LINE-1 in lung cancer. PLoS One 2021; 16:e0256254. [PMID: 34403448 PMCID: PMC8370637 DOI: 10.1371/journal.pone.0256254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 08/04/2021] [Indexed: 11/18/2022] Open
Abstract
Highly methylated Long Interspersed Nucleotide Elements 1 (LINE-1) constitute approximately 20% of the human genome, thus serving as a surrogate marker of global genomic DNA methylation. To date, there is still lacking a consensus about the precise location in LINE-1 promoter and its methylation threshold value, making challenging the use of LINE-1 methylation as a diagnostic, prognostic markers in cancer. This study reports on a technical standardization of bisulfite-based DNA methylation analysis, which ensures the complete bisulfite conversion of repeated LINE-1 sequences, thus allowing accurate LINE-1 methylation value. In addition, the study also indicated the precise location in LINE-1 promoter of which significant variance in methylation level makes LINE-1 methylation as a potential diagnostic biomarker for lung cancer. A serial concentration of 5-50-500 ng of DNA from 275 formalin-fixed paraffin-embedded lung tissues were converted by bisulfite; methylation level of two local regions (at nucleotide position 300–368 as LINE-1.1 and 368–460 as LINE-1.2) in LINE-1 promoter was measured by real time PCR. The use of 5 ng of genomic DNA but no more allowed to detect LINE-1 hypomethylation in lung cancer tissue (14.34% versus 16.69% in non-cancerous lung diseases for LINE-1.1, p < 0.0001, and 30.28% versus 32.35% for LINE-1.2, p < 0.05). Our study thus highlighted the optimal and primordial concentration less than 5 ng of genomic DNA guarantees the complete LINE-1 bisulfite conversion, and significant variance in methylation level of the LINE-1 sequence position from 300 to 368 allowed to discriminate lung cancer from non-cancer samples.
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Affiliation(s)
| | - Son Duc Le
- Faculty of Biology, University of Science, Vietnam National University, Hanoi, Vietnam
| | - Trang Mai Doan
- Faculty of Biology, University of Science, Vietnam National University, Hanoi, Vietnam
| | - Phuong Thu Luu
- Faculty of Biology, University of Science, Vietnam National University, Hanoi, Vietnam
| | - Uyen Quynh Nguyen
- Department of Biology, VNU Institute of Microbiology and Biotechnology, Hanoi, Vietnam
| | - Son Van Ho
- Department of Biochemistry, 175 Hospital, Ho Chi Minh City, Vietnam
| | - Lan Thi Thuong Vo
- Faculty of Biology, University of Science, Vietnam National University, Hanoi, Vietnam
- * E-mail:
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31
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White TL, Gonsalves MA. Dignity neuroscience: universal rights are rooted in human brain science. Ann N Y Acad Sci 2021; 1505:40-54. [PMID: 34350987 PMCID: PMC9291326 DOI: 10.1111/nyas.14670] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/25/2021] [Accepted: 07/08/2021] [Indexed: 01/22/2023]
Abstract
Universal human rights are defined by international agreements, law, foreign policy, and the concept of inherent human dignity. However, rights defined on this basis can be readily subverted by overt and covert disagreements and can be treated as distant geopolitical events rather than bearing on individuals’ everyday lives. A robust case for universal human rights is urgently needed and must meet several disparate requirements: (1) a framework that resolves tautological definitions reached solely by mutual, revocable agreement; (2) a rationale that transcends differences in beliefs, creed, and culture; and (3) a personalization that empowers both individuals and governments to further human rights protections. We propose that human rights in existing agreements comprise five elemental types: (1) agency, autonomy, and self‐determination; (2) freedom from want; (3) freedom from fear; (4) uniqueness; and (5) unconditionality, including protections for vulnerable populations. We further propose these rights and protections are rooted in fundamental properties of the human brain. We provide a robust, empirical foundation for universal rights based on emerging work in human brain science that we term dignity neuroscience. Dignity neuroscience provides an empirical foundation to support and foster human dignity, universal rights, and their active furtherance by individuals, nations, and international law.
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Affiliation(s)
- Tara L White
- Department of Behavioral and Social Sciences, School of Public Health, Brown University, Providence, Rhode Island.,Center for Alcohol and Addiction Studies, Brown University, Providence, Rhode Island.,Carney Institute for Brain Science, Brown University, Providence, Rhode Island.,University of Cambridge, England, Cambridge, UK
| | - Meghan A Gonsalves
- Neuroscience Graduate Program, Brown University, Providence, Rhode Island
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32
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RNA m 6A modification orchestrates a LINE-1-host interaction that facilitates retrotransposition and contributes to long gene vulnerability. Cell Res 2021; 31:861-885. [PMID: 34108665 PMCID: PMC8324889 DOI: 10.1038/s41422-021-00515-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 04/27/2021] [Indexed: 02/06/2023] Open
Abstract
The molecular basis underlying the interaction between retrotransposable elements (RTEs) and the human genome remains poorly understood. Here, we profiled N6-methyladenosine (m6A) deposition on nascent RNAs in human cells by developing a new method MINT-Seq, which revealed that many classes of RTE RNAs, particularly intronic LINE-1s (L1s), are strongly methylated. These m6A-marked intronic L1s (MILs) are evolutionarily young, sense-oriented to hosting genes, and are bound by a dozen RNA binding proteins (RBPs) that are putative novel readers of m6A-modified RNAs, including a nuclear matrix protein SAFB. Notably, m6A positively controls the expression of both autonomous L1s and co-transcribed L1 relics, promoting L1 retrotransposition. We showed that MILs preferentially reside in long genes with critical roles in DNA damage repair and sometimes in L1 suppression per se, where they act as transcriptional "roadblocks" to impede the hosting gene expression, revealing a novel host-weakening strategy by the L1s. In counteraction, the host uses the SAFB reader complex to bind m6A-L1s to reduce their levels, and to safeguard hosting gene transcription. Remarkably, our analysis identified thousands of MILs in multiple human fetal tissues, enlisting them as a novel category of cell-type-specific regulatory elements that often compromise transcription of long genes and confer their vulnerability in neurodevelopmental disorders. We propose that this m6A-orchestrated L1-host interaction plays widespread roles in gene regulation, genome integrity, human development and diseases.
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33
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Pasquesi GIM, Perry BW, Vandewege MW, Ruggiero RP, Schield DR, Castoe TA. Vertebrate Lineages Exhibit Diverse Patterns of Transposable Element Regulation and Expression across Tissues. Genome Biol Evol 2021; 12:506-521. [PMID: 32271917 PMCID: PMC7211425 DOI: 10.1093/gbe/evaa068] [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] [Accepted: 04/02/2020] [Indexed: 12/11/2022] Open
Abstract
Transposable elements (TEs) comprise a major fraction of vertebrate genomes, yet little is known about their expression and regulation across tissues, and how this varies across major vertebrate lineages. We present the first comparative analysis integrating TE expression and TE regulatory pathway activity in somatic and gametic tissues for a diverse set of 12 vertebrates. We conduct simultaneous gene and TE expression analyses to characterize patterns of TE expression and TE regulation across vertebrates and examine relationships between these features. We find remarkable variation in the expression of genes involved in TE negative regulation across tissues and species, yet consistently high expression in germline tissues, particularly in testes. Most vertebrates show comparably high levels of TE regulatory pathway activity across gonadal tissues except for mammals, where reduced activity of TE regulatory pathways in ovarian tissues may be the result of lower relative germ cell densities. We also find that all vertebrate lineages examined exhibit remarkably high levels of TE-derived transcripts in somatic and gametic tissues, with recently active TE families showing higher expression in gametic tissues. Although most TE-derived transcripts originate from inactive ancient TE families (and are likely incapable of transposition), such high levels of TE-derived RNA in the cytoplasm may have secondary, unappreciated biological relevance.
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Affiliation(s)
- Giulia I M Pasquesi
- Department of Biology, University of Texas at Arlington.,Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder
| | - Blair W Perry
- Department of Biology, University of Texas at Arlington
| | | | | | - Drew R Schield
- Department of Biology, University of Texas at Arlington.,Department of Ecology and Evolutionary Biology, University of Colorado, Boulder
| | - Todd A Castoe
- Department of Biology, University of Texas at Arlington
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34
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Frassinelli L, Orecchini E, Al-Wardat S, Tripodi M, Mancone C, Doria M, Galardi S, Ciafrè SA, Michienzi A. The RNA editing enzyme ADAR2 restricts L1 mobility. RNA Biol 2021; 18:75-87. [PMID: 34224323 PMCID: PMC8677026 DOI: 10.1080/15476286.2021.1940020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Adenosine deaminases acting on RNA (ADARs) are enzymes that convert adenosines to inosines in double-stranded RNAs (RNA editing A-to-I). ADAR1 and ADAR2 were previously reported as HIV-1 proviral factors. The aim of this study was to investigate the composition of the ADAR2 ribonucleoprotein complex during HIV-1 expression. By using a dual-tag affinity purification procedure in cells expressing HIV-1 followed by mass spectrometry analysis, we identified 10 non-ribosomal ADAR2-interacting factors. A significant fraction of these proteins was previously found associated to the Long INterspersed Element 1 (LINE1 or L1) ribonucleoparticles and to regulate the life cycle of L1 retrotransposons. Considering that we previously demonstrated that ADAR1 is an inhibitor of LINE-1 retrotransposon activity, we investigated whether also ADAR2 played a similar function. To reach this goal, we performed specific cell culture retrotransposition assays in cells overexpressing or ablated for ADAR2. These experiments unveil a novel function of ADAR2 as suppressor of L1 retrotransposition. Furthermore, we showed that ADAR2 binds the basal L1 RNP complex. Overall, these data support the role of ADAR2 as regulator of L1 life cycle.
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Affiliation(s)
- Loredana Frassinelli
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Rome, Italy
| | - Elisa Orecchini
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Rome, Italy
| | - Sofian Al-Wardat
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Rome, Italy
| | - Marco Tripodi
- National Institute for Infectious Diseases L. Spallanzani, IRCCS, Rome, Italy.,Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Carmine Mancone
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Margherita Doria
- Unit of Primary Immunodeficiency, Bambino Gesu` Children's Hospital, IRCCS, Rome, Italy
| | - Silvia Galardi
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Rome, Italy
| | - Silvia Anna Ciafrè
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Rome, Italy
| | - Alessandro Michienzi
- Department of Biomedicine and Prevention, University of Rome 'Tor Vergata', Rome, Italy
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35
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McDonald TL, Zhou W, Castro CP, Mumm C, Switzenberg JA, Mills RE, Boyle AP. Cas9 targeted enrichment of mobile elements using nanopore sequencing. Nat Commun 2021; 12:3586. [PMID: 34117247 PMCID: PMC8196195 DOI: 10.1038/s41467-021-23918-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 05/25/2021] [Indexed: 02/05/2023] Open
Abstract
Mobile element insertions (MEIs) are repetitive genomic sequences that contribute to genetic variation and can lead to genetic disorders. Targeted and whole-genome approaches using short-read sequencing have been developed to identify reference and non-reference MEIs; however, the read length hampers detection of these elements in complex genomic regions. Here, we pair Cas9-targeted nanopore sequencing with computational methodologies to capture active MEIs in human genomes. We demonstrate parallel enrichment for distinct classes of MEIs, averaging 44% of reads on-targeted signals and exhibiting a 13.4-54x enrichment over whole-genome approaches. We show an individual flow cell can recover most MEIs (97% L1Hs, 93% AluYb, 51% AluYa, 99% SVA_F, and 65% SVA_E). We identify seventeen non-reference MEIs in GM12878 overlooked by modern, long-read analysis pipelines, primarily in repetitive genomic regions. This work introduces the utility of nanopore sequencing for MEI enrichment and lays the foundation for rapid discovery of elusive, repetitive genetic elements.
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Affiliation(s)
- Torrin L McDonald
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Weichen Zhou
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Christopher P Castro
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Camille Mumm
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Jessica A Switzenberg
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Ryan E Mills
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA.
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA.
| | - Alan P Boyle
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA.
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA.
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36
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Chu C, Zhao B, Park PJ, Lee EA. Identification and Genotyping of Transposable Element Insertions From Genome Sequencing Data. ACTA ACUST UNITED AC 2021; 107:e102. [PMID: 32662945 DOI: 10.1002/cphg.102] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Transposable element (TE) mobilization is a significant source of genomic variation and has been associated with various human diseases. The exponential growth of population-scale whole-genome sequencing and rapid innovations in long-read sequencing technologies provide unprecedented opportunities to study TE insertions and their functional impact in human health and disease. Identifying TE insertions, however, is challenging due to the repetitive nature of the TE sequences. Here, we review computational approaches to detecting and genotyping TE insertions using short- and long-read sequencing and discuss the strengths and weaknesses of different approaches. © 2020 Wiley Periodicals LLC.
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Affiliation(s)
- Chong Chu
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts
| | - Boxun Zhao
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, Massachusetts.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.,Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Peter J Park
- Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts
| | - Eunjung Alice Lee
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, Massachusetts.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.,Broad Institute of MIT and Harvard, Cambridge, Massachusetts
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37
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Siudeja K, van den Beek M, Riddiford N, Boumard B, Wurmser A, Stefanutti M, Lameiras S, Bardin AJ. Unraveling the features of somatic transposition in the Drosophila intestine. EMBO J 2021; 40:e106388. [PMID: 33634906 PMCID: PMC8090852 DOI: 10.15252/embj.2020106388] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 01/20/2021] [Accepted: 01/27/2021] [Indexed: 12/22/2022] Open
Abstract
Transposable elements (TEs) play a significant role in evolution, contributing to genetic variation. However, TE mobilization in somatic cells is not well understood. Here, we address the prevalence of transposition in a somatic tissue, exploiting the Drosophila midgut as a model. Using whole-genome sequencing of in vivo clonally expanded gut tissue, we have mapped hundreds of high-confidence somatic TE integration sites genome-wide. We show that somatic retrotransposon insertions are associated with inactivation of the tumor suppressor Notch, likely contributing to neoplasia formation. Moreover, applying Oxford Nanopore long-read sequencing technology we provide evidence for tissue-specific differences in retrotransposition. Comparing somatic TE insertional activity with transcriptomic and small RNA sequencing data, we demonstrate that transposon mobility cannot be simply predicted by whole tissue TE expression levels or by small RNA pathway activity. Finally, we reveal that somatic TE insertions in the adult fly intestine are enriched in genic regions and in transcriptionally active chromatin. Together, our findings provide clear evidence of ongoing somatic transposition in Drosophila and delineate previously unknown features underlying somatic TE mobility in vivo.
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Affiliation(s)
- Katarzyna Siudeja
- Institut CurieCNRSUMR 3215INSERM U934Stem Cells and Tissue Homeostasis GroupPSL Research UniversityParisFrance
- Sorbonne UniversitésUPMC Univ Paris 6ParisFrance
| | - Marius van den Beek
- Institut CurieCNRSUMR 3215INSERM U934Stem Cells and Tissue Homeostasis GroupPSL Research UniversityParisFrance
- Sorbonne UniversitésUPMC Univ Paris 6ParisFrance
| | - Nick Riddiford
- Institut CurieCNRSUMR 3215INSERM U934Stem Cells and Tissue Homeostasis GroupPSL Research UniversityParisFrance
- Sorbonne UniversitésUPMC Univ Paris 6ParisFrance
| | - Benjamin Boumard
- Institut CurieCNRSUMR 3215INSERM U934Stem Cells and Tissue Homeostasis GroupPSL Research UniversityParisFrance
- Sorbonne UniversitésUPMC Univ Paris 6ParisFrance
| | - Annabelle Wurmser
- Institut CurieCNRSUMR 3215INSERM U934Stem Cells and Tissue Homeostasis GroupPSL Research UniversityParisFrance
- Sorbonne UniversitésUPMC Univ Paris 6ParisFrance
| | - Marine Stefanutti
- Institut CurieCNRSUMR 3215INSERM U934Stem Cells and Tissue Homeostasis GroupPSL Research UniversityParisFrance
- Sorbonne UniversitésUPMC Univ Paris 6ParisFrance
| | - Sonia Lameiras
- ICGex Next‐Generation Sequencing PlatformInstitut CuriePSL Research UniversityParisFrance
| | - Allison J Bardin
- Institut CurieCNRSUMR 3215INSERM U934Stem Cells and Tissue Homeostasis GroupPSL Research UniversityParisFrance
- Sorbonne UniversitésUPMC Univ Paris 6ParisFrance
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38
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Stenz L. The L1-dependant and Pol III transcribed Alu retrotransposon, from its discovery to innate immunity. Mol Biol Rep 2021; 48:2775-2789. [PMID: 33725281 PMCID: PMC7960883 DOI: 10.1007/s11033-021-06258-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/26/2021] [Indexed: 02/07/2023]
Abstract
The 300 bp dimeric repeats digestible by AluI were discovered in 1979. Since then, Alu were involved in the most fundamental epigenetic mechanisms, namely reprogramming, pluripotency, imprinting and mosaicism. These Alu encode a family of retrotransposons transcribed by the RNA Pol III machinery, notably when the cytosines that constitute their sequences are de-methylated. Then, Alu hijack the functions of ORF2 encoded by another transposons named L1 during reverse transcription and integration into new sites. That mechanism functions as a complex genetic parasite able to copy-paste Alu sequences. Doing that, Alu have modified even the size of the human genome, as well as of other primate genomes, during 65 million years of co-evolution. Actually, one germline retro-transposition still occurs each 20 births. Thus, Alu continue to modify our human genome nowadays and were implicated in de novo mutation causing diseases including deletions, duplications and rearrangements. Most recently, retrotransposons were found to trigger neuronal diversity by inducing mosaicism in the brain. Finally, boosted during viral infections, Alu clearly interact with the innate immune system. The purpose of that review is to give a condensed overview of all these major findings that concern the fascinating physiology of Alu from their discovery up to the current knowledge.
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Affiliation(s)
- Ludwig Stenz
- Department of Genetic Medicine and Development, Faculty of Medicine, Geneva University, Geneva, Switzerland. .,Swiss Centre for Applied Human Toxicology, University of Basel, Basel, Switzerland.
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Fontana C, Marasca F, Provitera L, Mancinelli S, Pesenti N, Sinha S, Passera S, Abrignani S, Mosca F, Lodato S, Bodega B, Fumagalli M. Early maternal care restores LINE-1 methylation and enhances neurodevelopment in preterm infants. BMC Med 2021; 19:42. [PMID: 33541338 PMCID: PMC7863536 DOI: 10.1186/s12916-020-01896-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 12/22/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Preterm birth affects almost 9-11% of newborns and is one of the leading causes of childhood neurodevelopmental disabilities; the underlying molecular networks are poorly defined. In neurons, retrotransposons LINE-1 (L1) are an active source of genomic mosaicism that is deregulated in several neurological disorders; early life experience has been shown to regulate L1 activity in mice. METHODS Very preterm infants were randomized to receive standard care or early intervention. L1 methylation was measured at birth and at hospital discharge. At 12 and 36 months, infants' neurodevelopment was evaluated with the Griffiths Scales. L1 methylation and CNVs were measured in mouse brain areas at embryonic and postnatal stages. RESULTS Here we report that L1 promoter is hypomethylated in preterm infants at birth and that an early intervention program, based on enhanced maternal care and positive multisensory stimulation, restores L1 methylation levels comparable to healthy newborns and ameliorates neurodevelopment in childhood. We further show that L1 activity is fine-tuned in the perinatal mouse brain, suggesting a sensitive and vulnerable window for the L1 epigenetic setting. CONCLUSIONS Our results open the field on the inspection of L1 activity as a novel molecular and predictive approach to infants' prematurity-related neurodevelopmental outcomes. TRIAL REGISTRATION ClinicalTrial.gov ( NCT02983513 ). Registered on 6 December 2016, retrospectively registered.
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Affiliation(s)
- Camilla Fontana
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Federica Marasca
- Istituto Nazionale di Genetica Molecolare "Enrica e Romeo Invernizzi" (INGM), Milan, Italy
| | - Livia Provitera
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, NICU, Milan, Italy
| | - Sara Mancinelli
- Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, Milan, Italy.,IRCCS Humanitas Clinical and Research Center, Rozzano, Milan, Italy
| | - Nicola Pesenti
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, NICU, Milan, Italy.,Department of Statistics and Quantitative Methods, Division of Biostatistics, Epidemiology and Public Health, University of Milano-Bicocca, Milan, Italy
| | - Shruti Sinha
- Istituto Nazionale di Genetica Molecolare "Enrica e Romeo Invernizzi" (INGM), Milan, Italy
| | - Sofia Passera
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, NICU, Milan, Italy
| | - Sergio Abrignani
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.,Istituto Nazionale di Genetica Molecolare "Enrica e Romeo Invernizzi" (INGM), Milan, Italy
| | - Fabio Mosca
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.,Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, NICU, Milan, Italy
| | - Simona Lodato
- Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, Milan, Italy.,IRCCS Humanitas Clinical and Research Center, Rozzano, Milan, Italy
| | - Beatrice Bodega
- Istituto Nazionale di Genetica Molecolare "Enrica e Romeo Invernizzi" (INGM), Milan, Italy.
| | - Monica Fumagalli
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy. .,Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, NICU, Milan, Italy.
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40
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Garcia-Outeiral V, de la Parte C, Fidalgo M, Guallar D. The Complexity of TET2 Functions in Pluripotency and Development. Front Cell Dev Biol 2021; 8:630754. [PMID: 33537318 PMCID: PMC7848104 DOI: 10.3389/fcell.2020.630754] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 12/22/2020] [Indexed: 12/14/2022] Open
Abstract
Ten-eleven translocation-2 (TET2) is a crucial driver of cell fate outcomes in a myriad of biological processes, including embryonic development and tissue homeostasis. TET2 catalyzes the demethylation of 5-methylcytosine on DNA, affecting transcriptional regulation. New exciting research has provided evidence for TET2 catalytic activity in post-transcriptional regulation through RNA hydroxymethylation. Here we review the current understanding of TET2 functions on both DNA and RNA, and the influence of these chemical modifications in normal development and pluripotency contexts, highlighting TET2 versatility in influencing genome regulation and cellular phenotypes.
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Affiliation(s)
- Vera Garcia-Outeiral
- Stem Cells and Human Diseases Group, Department of Physiology, Center for Research in Molecular Medicine and Chronic Diseases, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Cristina de la Parte
- Epitranscriptomics and Ageing Group, Department of Biochemistry and Molecular Biology, Center for Research in Molecular Medicine and Chronic Diseases, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Miguel Fidalgo
- Stem Cells and Human Diseases Group, Department of Physiology, Center for Research in Molecular Medicine and Chronic Diseases, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Diana Guallar
- Epitranscriptomics and Ageing Group, Department of Biochemistry and Molecular Biology, Center for Research in Molecular Medicine and Chronic Diseases, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
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41
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Recognize Yourself-Innate Sensing of Non-LTR Retrotransposons. Viruses 2021; 13:v13010094. [PMID: 33445593 PMCID: PMC7827607 DOI: 10.3390/v13010094] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/18/2020] [Accepted: 12/19/2020] [Indexed: 12/13/2022] Open
Abstract
Although mobile genetic elements, or transposons, have played an important role in genome evolution, excess activity of mobile elements can have detrimental consequences. Already, the enhanced expression of transposons-derived nucleic acids can trigger autoimmune reactions that may result in severe autoinflammatory disorders. Thus, cells contain several layers of protective measures to restrict transposons and to sense the enhanced activity of these “intragenomic pathogens”. This review focuses on our current understanding of immunogenic patterns derived from the most active elements in humans, the retrotransposons long interspersed element (LINE)-1 and Alu. We describe the role of known pattern recognition receptors in nucleic acid sensing of LINE-1 and Alu and the possible consequences for autoimmune diseases.
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42
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Al Zouabi L, Bardin AJ. Stem Cell DNA Damage and Genome Mutation in the Context of Aging and Cancer Initiation. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a036210. [PMID: 31932318 DOI: 10.1101/cshperspect.a036210] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Adult stem cells fuel tissue homeostasis and regeneration through their unique ability to self-renew and differentiate into specialized cells. Thus, their DNA provides instructions that impact the tissue as a whole. Since DNA is not an inert molecule, but rather dynamic, interacting with a myriad of chemical and physical factors, it encounters damage from both endogenous and exogenous sources. Damage to DNA introduces deviations from its normal intact structure and, if left unrepaired, may result in a genetic mutation. In turn, mutant genomes of stem and progenitor cells are inherited in cells of the lineage, thus eroding the genetic information that maintains homeostasis of the somatic cell population. Errors arising in stem and progenitor cells will have a substantially larger impact on the tissue in which they reside than errors occurring in postmitotic differentiated cells. Therefore, maintaining the integrity of genomic DNA within our stem cells is essential to protect the instructions necessary for rebuilding healthy tissues during homeostatic renewal. In this review, we will first discuss DNA damage arising in stem cells and cell- and tissue-intrinsic mechanisms that protect against harmful effects of this damage. Secondly, we will examine how erroneous DNA repair and persistent DNA damage in stem and progenitor cells impact stem cells and tissues in the context of cancer initiation and aging. Finally, we will discuss the use of invertebrate and vertebrate model systems to address unanswered questions on the role that DNA damage and mutation may play in aging and precancerous conditions.
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Affiliation(s)
- Lara Al Zouabi
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, Stem Cells and Tissue Homeostasis Group, 75248 Paris, France.,Sorbonne Universités, UPMC University, Paris 6, France
| | - Allison J Bardin
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, Stem Cells and Tissue Homeostasis Group, 75248 Paris, France.,Sorbonne Universités, UPMC University, Paris 6, France
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43
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Kaeser G, Chun J. Brain cell somatic gene recombination and its phylogenetic foundations. J Biol Chem 2020; 295:12786-12795. [PMID: 32699111 PMCID: PMC7476723 DOI: 10.1074/jbc.rev120.009192] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 07/22/2020] [Indexed: 12/19/2022] Open
Abstract
A new form of somatic gene recombination (SGR) has been identified in the human brain that affects the Alzheimer's disease gene, amyloid precursor protein (APP). SGR occurs when a gene sequence is cut and recombined within a single cell's genomic DNA, generally independent of DNA replication and the cell cycle. The newly identified brain SGR produces genomic complementary DNAs (gencDNAs) lacking introns, which integrate into locations distinct from germline loci. This brief review will present an overview of likely related recombination mechanisms and genomic cDNA-like sequences that implicate evolutionary origins for brain SGR. Similarities and differences exist between brain SGR and VDJ recombination in the immune system, the first identified SGR form that now has a well-defined enzymatic machinery. Both require gene transcription, but brain SGR uses an RNA intermediate and reverse transcriptase (RT) activity, which are characteristics shared with endogenous retrotransposons. The identified gencDNAs have similarities to other cDNA-like sequences existing throughout phylogeny, including intron-less genes and inactive germline processed pseudogenes, with likely overlapping biosynthetic processes. gencDNAs arise somatically in an individual to produce multiple copies; can be functional; appear most frequently within postmitotic cells; have diverse sequences; change with age; and can change with disease state. Normally occurring brain SGR may represent a mechanism for gene optimization and long-term cellular memory, whereas its dysregulation could underlie multiple brain disorders and, potentially, other diseases like cancer. The involvement of RT activity implicates already Food and Drug Administration-approved RT inhibitors as possible near-term interventions for managing SGR-associated diseases and suggest next-generation therapeutics targeting SGR elements.
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Affiliation(s)
- Gwendolyn Kaeser
- Degenerative Disease Program at the Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Jerold Chun
- Degenerative Disease Program at the Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
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44
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Liudkovska V, Dziembowski A. Functions and mechanisms of RNA tailing by metazoan terminal nucleotidyltransferases. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1622. [PMID: 33145994 PMCID: PMC7988573 DOI: 10.1002/wrna.1622] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 12/28/2022]
Abstract
Termini often determine the fate of RNA molecules. In recent years, 3' ends of almost all classes of RNA species have been shown to acquire nontemplated nucleotides that are added by terminal nucleotidyltransferases (TENTs). The best-described role of 3' tailing is the bulk polyadenylation of messenger RNAs in the cell nucleus that is catalyzed by canonical poly(A) polymerases (PAPs). However, many other enzymes that add adenosines, uridines, or even more complex combinations of nucleotides have recently been described. This review focuses on metazoan TENTs, which are either noncanonical PAPs or terminal uridylyltransferases with varying processivity. These enzymes regulate RNA stability and RNA functions and are crucial in early development, gamete production, and somatic tissues. TENTs regulate gene expression at the posttranscriptional level, participate in the maturation of many transcripts, and protect cells against viral invasion and the transposition of repetitive sequences. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Processing > 3' End Processing RNA Turnover and Surveillance > Regulation of RNA Stability.
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Affiliation(s)
- Vladyslava Liudkovska
- Laboratory of RNA Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Andrzej Dziembowski
- Laboratory of RNA Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland.,Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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45
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Loss of Nuclear TDP-43 Is Associated with Decondensation of LINE Retrotransposons. Cell Rep 2020; 27:1409-1421.e6. [PMID: 31042469 PMCID: PMC6508629 DOI: 10.1016/j.celrep.2019.04.003] [Citation(s) in RCA: 125] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 02/14/2019] [Accepted: 03/27/2019] [Indexed: 12/13/2022] Open
Abstract
Loss of the nuclear RNA binding protein TAR DNA binding protein-43 (TDP-43) into cytoplasmic aggregates is the strongest correlate to neurodegeneration in amyotrophic lateral sclerosis and frontotemporal degeneration. The molecular changes associated with the loss of nuclear TDP-43 in human tissues are not entirely known. Using subcellular fractionation andfluorescent-activated cell sorting to enrich for diseased neuronal nuclei without TDP-43 from post-mortem frontotemporal degeneration-amyotro-phic lateral sclerosis (FTD-ALS) human brain, we characterized the effects of TDP-43 loss on the transcriptome and chromatin accessibility. Nuclear TDP-43 loss is associated with gene expression changes that affect RNA processing, nucleocytoplas-mic transport, histone processing, and DNA damage. Loss of nuclear TDP-43 is also associated with chromatin decondensation around long interspersed nuclear elements (LINEs) and increased LINE1 DNA content. Moreover, loss of TDP-43 leads to increased retrotransposition that can be inhibited with antiretro-viral drugs, suggesting that TDP-43 neuropathology is associated with altered chromatin structure including decondensation of LINEs. Liu et al. fractionated and sorted for diseased neuronal nuclei from post-mortem FTD-ALS human brains and showed that loss of an RNA-binding protein, TDP-43, altered the transcriptome and chromatin accessibility. Their results suggest that loss of nuclear TDP-43 is associated with decondensation of LINE retrotransposons.
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46
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Lanciano S, Cristofari G. Measuring and interpreting transposable element expression. Nat Rev Genet 2020; 21:721-736. [PMID: 32576954 DOI: 10.1038/s41576-020-0251-y] [Citation(s) in RCA: 161] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2020] [Indexed: 12/21/2022]
Abstract
Transposable elements (TEs) are insertional mutagens that contribute greatly to the plasticity of eukaryotic genomes, influencing the evolution and adaptation of species as well as physiology or disease in individuals. Measuring TE expression helps to understand not only when and where TE mobilization can occur but also how this process alters gene expression, chromatin accessibility or cellular signalling pathways. Although genome-wide gene expression assays such as RNA sequencing include transposon-derived transcripts, most computational analytical tools discard or misinterpret TE-derived reads. Emerging approaches are improving the identification of expressed TE loci and helping to discriminate TE transcripts that permit TE mobilization from chimeric gene-TE transcripts or pervasive transcription. Here we review the main challenges associated with the detection of TE expression, including mappability, insertional and internal sequence polymorphisms, and the diversity of the TE transcriptional landscape, as well as the different experimental and computational strategies to solve them.
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47
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Abstract
Transposable elements (TEs) are genomic parasites that are found in all genomes, some of which display sequence similarity to certain viruses. In insects, TEs are controlled by the Piwi-interacting small interfering RNA (piRNA) pathway in gonads, while the small interfering RNA (siRNA) pathway is dedicated to TE somatic control and defense against viruses. So far, these two small interfering RNA pathways are considered to involve distinct molecular effectors and are described as independent. Using Sindbis virus (SINV) in Drosophila, here we show that viral infections affect TE transcript amounts via modulations of the piRNA and siRNA repertoires, with the clearest effects in somatic tissues. These results suggest that viral acute or chronic infections may impact TE activity and, thus, the tempo of genetic diversification. In addition, these results deserve further evolutionary considerations regarding potential benefits to the host, the virus, or the TEs.
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48
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Del Re B, Giorgi G. Long INterspersed element-1 mobility as a sensor of environmental stresses. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:465-493. [PMID: 32144842 DOI: 10.1002/em.22366] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 03/03/2020] [Accepted: 03/04/2020] [Indexed: 06/10/2023]
Abstract
Long INterspersed element (LINE-1, L1) retrotransposons are the most abundant transposable elements in the human genome, constituting approximately 17%. They move by a "copy-paste" mechanism, involving reverse transcription of an RNA intermediate and insertion of its cDNA copy at a new site in the genome. L1 retrotransposition (L1-RTP) can cause insertional mutations, alter gene expression, transduce exons, and induce epigenetic dysregulation. L1-RTP is generally repressed; however, a number of observations collected over about 15 years revealed that it can occur in response to environmental stresses. Moreover, emerging evidence indicates that L1-RTP can play a role in the onset of several neurological and oncological diseases in humans. In recent years, great attention has been paid to the exposome paradigm, which proposes that health effects of an environmental factor should be evaluated considering both cumulative environmental exposures and the endogenous processes resulting from the biological response. L1-RTP could be an endogenous process considered for this application. Here, we summarize the current understanding of environmental factors that can affect the retrotransposition of human L1 elements. Evidence indicates that L1-RTP alteration is triggered by numerous and various environmental stressors, such as chemical agents (heavy metals, carcinogens, oxidants, and drugs), physical agents (ionizing and non-ionizing radiations), and experiential factors (voluntary exercise, social isolation, maternal care, and environmental light/dark cycles). These data come from in vitro studies on cell lines and in vivo studies on transgenic animals: future investigations should be focused on physiologically relevant models to gain a better understanding of this topic.
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Affiliation(s)
- Brunella Del Re
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, Bologna, Italy
| | - Gianfranco Giorgi
- Department of Biological, Geological and Environmental Sciences, Alma Mater Studiorum University of Bologna, Bologna, Italy
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49
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Zhou W, Emery SB, Flasch DA, Wang Y, Kwan KY, Kidd JM, Moran JV, Mills RE. Identification and characterization of occult human-specific LINE-1 insertions using long-read sequencing technology. Nucleic Acids Res 2020; 48:1146-1163. [PMID: 31853540 PMCID: PMC7026601 DOI: 10.1093/nar/gkz1173] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 11/14/2019] [Accepted: 12/05/2019] [Indexed: 11/13/2022] Open
Abstract
Long Interspersed Element-1 (LINE-1) retrotransposition contributes to inter- and intra-individual genetic variation and occasionally can lead to human genetic disorders. Various strategies have been developed to identify human-specific LINE-1 (L1Hs) insertions from short-read whole genome sequencing (WGS) data; however, they have limitations in detecting insertions in complex repetitive genomic regions. Here, we developed a computational tool (PALMER) and used it to identify 203 non-reference L1Hs insertions in the NA12878 benchmark genome. Using PacBio long-read sequencing data, we identified L1Hs insertions that were absent in previous short-read studies (90/203). Approximately 81% (73/90) of the L1Hs insertions reside within endogenous LINE-1 sequences in the reference assembly and the analysis of unique breakpoint junction sequences revealed 63% (57/90) of these L1Hs insertions could be genotyped in 1000 Genomes Project sequences. Moreover, we observed that amplification biases encountered in single-cell WGS experiments led to a wide variation in L1Hs insertion detection rates between four individual NA12878 cells; under-amplification limited detection to 32% (65/203) of insertions, whereas over-amplification increased false positive calls. In sum, these data indicate that L1Hs insertions are often missed using standard short-read sequencing approaches and long-read sequencing approaches can significantly improve the detection of L1Hs insertions present in individual genomes.
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Affiliation(s)
- Weichen Zhou
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA
| | - Sarah B Emery
- Department of Human Genetics, University of Michigan Medical School, 1241 East Catherine Street, Ann Arbor, MI 48109, USA
| | - Diane A Flasch
- Department of Human Genetics, University of Michigan Medical School, 1241 East Catherine Street, Ann Arbor, MI 48109, USA
| | - Yifan Wang
- Department of Human Genetics, University of Michigan Medical School, 1241 East Catherine Street, Ann Arbor, MI 48109, USA
| | - Kenneth Y Kwan
- Department of Human Genetics, University of Michigan Medical School, 1241 East Catherine Street, Ann Arbor, MI 48109, USA.,Molecular and Behavioral Neuroscience Institute, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Jeffrey M Kidd
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA.,Department of Human Genetics, University of Michigan Medical School, 1241 East Catherine Street, Ann Arbor, MI 48109, USA
| | - John V Moran
- Department of Human Genetics, University of Michigan Medical School, 1241 East Catherine Street, Ann Arbor, MI 48109, USA.,Department of Internal Medicine, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Ryan E Mills
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA.,Department of Human Genetics, University of Michigan Medical School, 1241 East Catherine Street, Ann Arbor, MI 48109, USA
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50
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McKerrow W, Tang Z, Steranka JP, Payer LM, Boeke JD, Keefe D, Fenyö D, Burns KH, Liu C. Human transposon insertion profiling by sequencing (TIPseq) to map LINE-1 insertions in single cells. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190335. [PMID: 32075555 PMCID: PMC7061987 DOI: 10.1098/rstb.2019.0335] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Long interspersed element-1 (LINE-1, L1) sequences, which comprise about 17% of human genome, are the product of one of the most active types of mobile DNAs in modern humans. LINE-1 insertion alleles can cause inherited and de novo genetic diseases, and LINE-1-encoded proteins are highly expressed in some cancers. Genome-wide LINE-1 mapping in single cells could be useful for defining somatic and germline retrotransposition rates, and for enabling studies to characterize tumour heterogeneity, relate insertions to transcriptional and epigenetic effects at the cellular level, or describe cellular phylogenies in development. Our laboratories have reported a genome-wide LINE-1 insertion site mapping method for bulk DNA, named transposon insertion profiling by sequencing (TIPseq). There have been significant barriers applying LINE-1 mapping to single cells, owing to the chimeric artefacts and features of repetitive sequences. Here, we optimize a modified TIPseq protocol and show its utility for LINE-1 mapping in single lymphoblastoid cells. Results from single-cell TIPseq experiments compare well to known LINE-1 insertions found by whole-genome sequencing and TIPseq on bulk DNA. Among the several approaches we tested, whole-genome amplification by multiple displacement amplification followed by restriction enzyme digestion, vectorette ligation and LINE-1-targeted PCR had the best assay performance. This article is part of a discussion meeting issue 'Crossroads between transposons and gene regulation'.
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Affiliation(s)
- Wilson McKerrow
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, USA
| | - Zuojian Tang
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, USA
| | - Jared P Steranka
- Department of Pathology, Johns Hopkins University School of Medicine, 733N Broadway, Baltimore, MD 21205, USA
| | - Lindsay M Payer
- Department of Pathology, Johns Hopkins University School of Medicine, 733N Broadway, Baltimore, MD 21205, USA
| | - Jef D Boeke
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, USA
| | - David Keefe
- Department of Obstetrics and Gynecology, New York University Langone School of Medicine, 462 First Avenue, New York, NY 10016, USA.,Department of Cell Biology, New York University Langone School of Medicine, 462 First Avenue, New York, NY 10016, USA
| | - David Fenyö
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, USA
| | - Kathleen H Burns
- Department of Pathology, Johns Hopkins University School of Medicine, 733N Broadway, Baltimore, MD 21205, USA.,McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, 733N Broadway, Baltimore, MD 21205, USA.,High Throughput (HiT) Biology Center, Johns Hopkins University School of Medicine, 733N Broadway, Baltimore, MD 21205, USA.,Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, 401N Broadway, Baltimore, MD 21231, USA
| | - Chunhong Liu
- Department of Pathology, Johns Hopkins University School of Medicine, 733N Broadway, Baltimore, MD 21205, USA
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