1
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Kines KJ, Sokolowski M, DeFreece C, Shareef A, deHaro DL, Belancio VP. Large Deletions, Cleavage of the Telomeric Repeat Sequence, and Reverse Transcriptase-Mediated DNA Damage Response Associated with Long Interspersed Element-1 ORF2p Enzymatic Activities. Genes (Basel) 2024; 15:143. [PMID: 38397133 PMCID: PMC10887698 DOI: 10.3390/genes15020143] [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: 12/22/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 02/25/2024] Open
Abstract
L1 elements can cause DNA damage and genomic variation via retrotransposition and the generation of endonuclease-dependent DNA breaks. These processes require L1 ORF2p protein that contains an endonuclease domain, which cuts genomic DNA, and a reverse transcriptase domain, which synthesizes cDNA. The complete impact of L1 enzymatic activities on genome stability and cellular function remains understudied, and the spectrum of L1-induced mutations, other than L1 insertions, is mostly unknown. Using an inducible system, we demonstrate that an ORF2p containing functional reverse transcriptase is sufficient to elicit DNA damage response even in the absence of the functional endonuclease. Using a TK/Neo reporter system that captures misrepaired DNA breaks, we demonstrate that L1 expression results in large genomic deletions that lack any signatures of L1 involvement. Using an in vitro cleavage assay, we demonstrate that L1 endonuclease efficiently cuts telomeric repeat sequences. These findings support that L1 could be an unrecognized source of disease-promoting genomic deletions, telomere dysfunction, and an underappreciated source of chronic RT-mediated DNA damage response in mammalian cells. Our findings expand the spectrum of biological processes that can be triggered by functional and nonfunctional L1s, which have impactful evolutionary- and health-relevant consequences.
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Affiliation(s)
- Kristine J. Kines
- Department of Structural and Cellular Biology, Tulane School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, USA
| | - Mark Sokolowski
- Department of Structural and Cellular Biology, Tulane School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, USA
| | - Cecily DeFreece
- Department of Biology, Xavier University of Louisiana, New Orleans, LA 70125, USA
| | - Afzaal Shareef
- Department of Structural and Cellular Biology, Tulane School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, USA
| | - Dawn L. deHaro
- Department of Structural and Cellular Biology, Tulane School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, USA
| | - Victoria P. Belancio
- Department of Structural and Cellular Biology, Tulane School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, USA
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2
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Romero MA, Mumford PW, Roberson PA, Osburn SC, Young KC, Sedivy JM, Roberts MD. Translational Significance of the LINE-1 Jumping Gene in Skeletal Muscle. Exerc Sport Sci Rev 2022; 50:185-193. [PMID: 35749745 PMCID: PMC9651911 DOI: 10.1249/jes.0000000000000301] [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] [Indexed: 02/02/2023]
Abstract
Retrotransposons are gene segments that proliferate in the genome, and the Long INterspersed Element 1 (LINE-1 or L1) retrotransposon is active in humans. Although older mammals show enhanced skeletal muscle L1 expression, exercise generally reverses this trend. We hypothesize skeletal muscle L1 expression influences muscle physiology, and additional innovative investigations are needed to confirm this hypothesis.
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Affiliation(s)
- Matthew A. Romero
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, California USA
| | - Petey W. Mumford
- Department of Exercise Science, Lindenwood University, St. Charles, Missouri USA
| | - Paul A. Roberson
- Department of Cellular and Molecular Physiology, College of Medicine, The Pennsylvania State University, Hershey, Pennsylvania USA
| | | | - Kaelin C. Young
- School of Kinesiology, Auburn University, Auburn, Alabama USA
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn, Auburn, Alabama, USA
| | - John M. Sedivy
- Department of Molecular Biology, Cell Biology and Biochemistry, Center on the Biology of Aging, Brown University, Providence, Rhode Island, USA
| | - Michael D. Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama USA
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn, Auburn, Alabama, USA
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3
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Osburn SC, Mesquita P, Neal FK, Rumbley M, Holmes MT, Ruple BA, Mobley CB, Brown MD, McCullough DJ, Kavazis AN, Roberts MD. Long-term voluntary wheel running effects on markers of Long Interspersed Nuclear Element-1 in skeletal muscle, liver, and brain tissue of female rats. Am J Physiol Cell Physiol 2022; 323:C907-C919. [PMID: 35938680 DOI: 10.1152/ajpcell.00234.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We sought to determine the effects of long-term voluntary wheel running on markers of Long Interspersed Nuclear Element-1 (L1) in skeletal muscle, liver, and the hippocampus of female rats. Additionally, markers of the cGAS-STING DNA sensing pathway that results in inflammation were interrogated. Female Lewis rats (n=34) were separated into one of three groups including a 6-month-old group to serve as a young comparator group (CTL, n=10), a group that had access to a running wheel for voluntary wheel running (EX, n=12), and an age-matched group that did not (SED, n=12). Both SED and EX groups were carried out from 6 months to 15 months of age. There were no significant differences in L1 mRNA expression for any of the tissues between groups. Methylation of the L1 promoter in the soleus and hippocampus was significantly higher in SED and EX compared to CTL (p<0.05). ORF1p expression was higher in older SED and EX rats compared to CTL for every tissue (p<0.05). There were no differences between groups for L1 mRNA or cGAS-STING pathway markers. Our results suggest there is an increased ORF1 protein expression across tissues with aging that is not mitigated by voluntary wheel running. Additionally, while previous data imply that L1 methylation changes may play a role in acute exercise for L1 RNA expression, this does not seem to occur during extended periods of voluntary wheel running.
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Affiliation(s)
- Shelby C Osburn
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Paulo Mesquita
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Frances K Neal
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Melissa Rumbley
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Matthew T Holmes
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Bradley A Ruple
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - C Brooks Mobley
- School of Kinesiology, Auburn University, Auburn, AL, United States
| | - Michael D Brown
- School of Public Health, University of Maryland, College Park, MD, United States
| | - Danielle J McCullough
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Edward Via College of Osteopathic Medicine, Auburn, AL, United States
| | | | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL, United States.,Edward Via College of Osteopathic Medicine, Auburn, AL, United States
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4
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Floreani L, Ansaloni F, Mangoni D, Agostoni E, Sanges R, Persichetti F, Gustincich S. Analysis of LINE1 Retrotransposons in Huntington’s Disease. Front Cell Neurosci 2022; 15:743797. [PMID: 35095420 PMCID: PMC8795916 DOI: 10.3389/fncel.2021.743797] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 12/27/2021] [Indexed: 12/27/2022] Open
Abstract
Transposable elements (TEs) are mobile genetic elements that made up about half the human genome. Among them, the autonomous non-LTR retrotransposon long interspersed nuclear element-1 (L1) is the only currently active TE in mammals and covers about 17% of the mammalian genome. L1s exert their function as structural elements in the genome, as transcribed RNAs to influence chromatin structure and as retrotransposed elements to shape genomic variation in somatic cells. L1s activity has been shown altered in several diseases of the nervous system. Huntington disease (HD) is a dominantly inherited neurodegenerative disorder caused by an expansion of a CAG repeat in the HTT gene which leads to a gradual loss of neurons most prominently in the striatum and, to a lesser extent, in cortical brain regions. The length of the expanded CAG tract is related to age at disease onset, with longer repeats leading to earlier onset. Here we carried out bioinformatic analysis of public RNA-seq data of a panel of HD mouse models showing that a decrease of L1 RNA expression recapitulates two hallmarks of the disease: it correlates to CAG repeat length and it occurs in the striatum, the site of neurodegeneration. Results were then experimentally validated in HttQ111 knock-in mice. The expression of L1-encoded proteins was independent from L1 RNA levels and differentially regulated in time and tissues. The pattern of expression L1 RNAs in human HD post-mortem brains showed similarity to mouse models of the disease. This work suggests the need for further study of L1s in HD and adds support to the current hypothesis that dysregulation of TEs may be involved in neurodegenerative diseases.
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Affiliation(s)
- Lavinia Floreani
- Area of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
| | - Federico Ansaloni
- Area of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
- Central RNA Laboratory, Istituto Italiano di Tecnologia—IIT, Genova, Italy
| | - Damiano Mangoni
- Central RNA Laboratory, Istituto Italiano di Tecnologia—IIT, Genova, Italy
| | - Elena Agostoni
- Area of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
| | - Remo Sanges
- Area of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
- Central RNA Laboratory, Istituto Italiano di Tecnologia—IIT, Genova, Italy
- *Correspondence: Remo Sanges,
| | - Francesca Persichetti
- Department of Health Sciences, University of Piemonte Orientale “ A. Avogadro,”Novara, Italy
- Francesca Persichetti,
| | - Stefano Gustincich
- Area of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
- Central RNA Laboratory, Istituto Italiano di Tecnologia—IIT, Genova, Italy
- Stefano Gustincich,
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5
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Fukuda S, Narendran S, Varshney A, Nagasaka Y, Wang SB, Ambati K, Apicella I, Pereira F, Fowler BJ, Yasuma T, Hirahara S, Yasuma R, Huang P, Yerramothu P, Makin RD, Wang M, Baker KL, Marion KM, Huang X, Baghdasaryan E, Ambati M, Ambati VL, Banerjee D, Bonilha VL, Tolstonog GV, Held U, Ogura Y, Terasaki H, Oshika T, Bhattarai D, Kim KB, Feldman SH, Aguirre JI, Hinton DR, Kerur N, Sadda SR, Schumann GG, Gelfand BD, Ambati J. Alu complementary DNA is enriched in atrophic macular degeneration and triggers retinal pigmented epithelium toxicity via cytosolic innate immunity. SCIENCE ADVANCES 2021; 7:eabj3658. [PMID: 34586848 PMCID: PMC8480932 DOI: 10.1126/sciadv.abj3658] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 08/05/2021] [Indexed: 05/08/2023]
Abstract
Long interspersed nuclear element-1 (L1)–mediated reverse transcription (RT) of Alu RNA into cytoplasmic Alu complementary DNA (cDNA) has been implicated in retinal pigmented epithelium (RPE) degeneration. The mechanism of Alu cDNA–induced cytotoxicity and its relevance to human disease are unknown. Here we report that Alu cDNA is highly enriched in the RPE of human eyes with geographic atrophy, an untreatable form of age-related macular degeneration. We demonstrate that the DNA sensor cGAS engages Alu cDNA to induce cytosolic mitochondrial DNA escape, which amplifies cGAS activation, triggering RPE degeneration via the inflammasome. The L1-extinct rice rat was resistant to Alu RNA–induced Alu cDNA synthesis and RPE degeneration, which were enabled upon L1-RT overexpression. Nucleoside RT inhibitors (NRTIs), which inhibit both L1-RT and inflammasome activity, and NRTI derivatives (Kamuvudines) that inhibit inflammasome, but not RT, both block Alu cDNA toxicity, identifying inflammasome activation as the terminal effector of RPE degeneration.
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Affiliation(s)
- Shinichi Fukuda
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Siddharth Narendran
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Aravind Eye Hospital System, Madurai, India
| | - Akhil Varshney
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Yosuke Nagasaka
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shao-bin Wang
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Kameshwari Ambati
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Ivana Apicella
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Felipe Pereira
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo 04023-062, Brazil
| | - Benjamin J. Fowler
- Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, KY, USA
| | - Tetsuhiro Yasuma
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo 04023-062, Brazil
| | - Shuichiro Hirahara
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Reo Yasuma
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Peirong Huang
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Praveen Yerramothu
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Ryan D. Makin
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Mo Wang
- Doheny Eye Institute, Los Angeles, CA, USA
| | | | | | | | - Elmira Baghdasaryan
- Doheny Eye Institute, Los Angeles, CA, USA
- Department of Ophthalmology, David Geffen School of Medicine, University of California–Los Angeles, Los Angeles, California, USA
| | - Meenakshi Ambati
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Center for Digital Image Evaluation, Charlottesville, VA, USA
| | - Vidya L. Ambati
- Center for Digital Image Evaluation, Charlottesville, VA, USA
| | - Daipayan Banerjee
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | | | - Genrich V. Tolstonog
- Department of Otolaryngology–Head and Neck Surgery, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Ulrike Held
- Department of Medical Biotechnology, Paul-Ehrlich-Institute, Langen, Germany
| | - Yuichiro Ogura
- Department of Ophthalmology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Hiroko Terasaki
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tetsuro Oshika
- Department of Ophthalmology, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
| | - Deepak Bhattarai
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, USA
| | - Kyung Bo Kim
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, USA
| | - Sanford H. Feldman
- Center for Comparative Medicine, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - J. Ignacio Aguirre
- Department of Physiological Sciences, University of Florida, Gainesville, FL, USA
| | - David R. Hinton
- Departments of Pathology and Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Nagaraj Kerur
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Srinivas R. Sadda
- Doheny Eye Institute, Los Angeles, CA, USA
- Department of Ophthalmology, David Geffen School of Medicine, University of California–Los Angeles, Los Angeles, California, USA
| | - Gerald G. Schumann
- Department of Medical Biotechnology, Paul-Ehrlich-Institute, Langen, Germany
| | - Bradley D. Gelfand
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Biomedical Engineering, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Jayakrishna Ambati
- Center for Advanced Vision Science, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Ophthalmology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, VA, USA
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA, USA
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6
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Stow EC, Kaul T, deHaro DL, Dem MR, Beletsky AG, Morales ME, Du Q, LaRosa AJ, Yang H, Smither E, Baddoo M, Ungerleider N, Deininger P, Belancio VP. Organ-, sex- and age-dependent patterns of endogenous L1 mRNA expression at a single locus resolution. Nucleic Acids Res 2021; 49:5813-5831. [PMID: 34023901 PMCID: PMC8191783 DOI: 10.1093/nar/gkab369] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 04/21/2021] [Accepted: 04/28/2021] [Indexed: 11/13/2022] Open
Abstract
Expression of L1 mRNA, the first step in the L1 copy-and-paste amplification cycle, is a prerequisite for L1-associated genomic instability. We used a reported stringent bioinformatics method to parse L1 mRNA transcripts and measure the level of L1 mRNA expressed in mouse and rat organs at a locus-specific resolution. This analysis determined that mRNA expression of L1 loci in rodents exhibits striking organ specificity with less than 0.8% of loci shared between organs of the same organism. This organ specificity in L1 mRNA expression is preserved in male and female mice and across age groups. We discovered notable differences in L1 mRNA expression between sexes with only 5% of expressed L1 loci shared between male and female mice. Moreover, we report that the levels of total L1 mRNA expression and the number and spectrum of expressed L1 loci fluctuate with age as independent variables, demonstrating different patterns in different organs and sexes. Overall, our comparisons between organs and sexes and across ages ranging from 2 to 22 months establish previously unforeseen dynamic changes in L1 mRNA expression in vivo. These findings establish the beginning of an atlas of endogenous L1 mRNA expression across a broad range of biological variables that will guide future studies.
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Affiliation(s)
- Emily C Stow
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA.,Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
| | - Tiffany Kaul
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA.,Department of Epidemiology, Tulane School of Public Health and Tropical Medicine, New Orleans, LA 70112 USA
| | - Dawn L deHaro
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA.,Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
| | - Madeleine R Dem
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA.,Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
| | - Anna G Beletsky
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA.,Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
| | - Maria E Morales
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA.,Department of Epidemiology, Tulane School of Public Health and Tropical Medicine, New Orleans, LA 70112 USA
| | - Qianhui Du
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA.,Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
| | - Alexis J LaRosa
- Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
| | - Hanlin Yang
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Emily Smither
- Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
| | - Melody Baddoo
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Nathan Ungerleider
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Prescott Deininger
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA.,Department of Epidemiology, Tulane School of Public Health and Tropical Medicine, New Orleans, LA 70112 USA
| | - Victoria P Belancio
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA.,Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
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7
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Mukherjee K, Sur D, Singh A, Rai S, Das N, Sekar R, Narindi S, Dhingra VK, Jat B, Balraam KVV, Agarwal SP, Mandal PK. Robust expression of LINE-1 retrotransposon encoded proteins in oral squamous cell carcinoma. BMC Cancer 2021; 21:628. [PMID: 34044801 PMCID: PMC8161598 DOI: 10.1186/s12885-021-08174-z] [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] [Received: 12/10/2020] [Accepted: 04/07/2021] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Oral Squamous Cell Carcinoma (OSCC) results from a series of genetic alteration in squamous cells. This particular type of cancer considers one of the most aggressive malignancies to control because of its frequent local invasions to the regional lymph node. Although several biomarkers have been reported, the key marker used to predict the behavior of the disease is largely unknown. Here we report Long INterpersed Element-1 (LINE1 or L1) retrotransposon activity in post-operative oral cancer samples. L1 is the only active retrotransposon occupying around 17% of the human genome with an estimated 500,000 copies. An active L1 encodes two proteins (L1ORF1p and L1ORF2p); both of which are critical in the process of retrotransposition. Several studies report that the L1 retrotransposon is highly active in many cancers. L1 activity is generally determined by assaying L1ORF1p because of its high expression and availability of the antibody. However, due to its lower expression and unavailability of a robust antibody, detection of L1ORF2p has been limited. L1ORF2p is the crucial protein in the process of retrotransposition as it provides endonuclease and reverse transcriptase (RT) activity. METHODS Immunohistochemistry and Western blotting were performed on the post-operative oral cancer samples and murine tissues. RESULTS Using in house novel antibodies against both the L1 proteins (L1ORF1p and L1ORF2p), we found L1 retrotransposon is extremely active in post-operative oral cancer tissues. Here, we report a novel human L1ORF2p antibody generated using an 80-amino-acid stretch from the RT domain, which is highly conserved among different species. The antibody detects significant L1ORF2p expression in human oral squamous cell carcinoma (OSCC) samples and murine germ tissues. CONCLUSIONS We report exceptionally high L1ORF1p and L1ORF2p expression in post-operative oral cancer samples. The novel L1ORF2p antibody reported in this study will serve as a useful tool to understand why L1 activity is deregulated in OSCC and how it contributes to the progression of this particular cancer. Cross-species reactivity of L1ORF2p antibody due to the conserved epitope will be useful to study the retrotransposon biology in mice and rat germ tissues.
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Affiliation(s)
- Koel Mukherjee
- Department of Biotechnology, IIT Roorkee, Roorkee, Uttarakhand India
| | - Debpali Sur
- Department of Biotechnology, IIT Roorkee, Roorkee, Uttarakhand India
| | - Abhijeet Singh
- Department of Head-Neck Surgery and Oncology, AIIMS Rishikesh, Rishikesh, Uttarakhand India
| | - Sandhya Rai
- Department of Biotechnology, IIT Roorkee, Roorkee, Uttarakhand India
| | | | - Rakshanya Sekar
- School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu India
| | | | - Vandana Kumar Dhingra
- Department of Head-Neck Surgery and Oncology, AIIMS Rishikesh, Rishikesh, Uttarakhand India
| | - Bhinyaram Jat
- Department of Head-Neck Surgery and Oncology, AIIMS Rishikesh, Rishikesh, Uttarakhand India
| | | | - Satya Prakash Agarwal
- Department of Head-Neck Surgery and Oncology, AIIMS Rishikesh, Rishikesh, Uttarakhand India
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8
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Fukuda S, Varshney A, Fowler BJ, Wang SB, Narendran S, Ambati K, Yasuma T, Magagnoli J, Leung H, Hirahara S, Nagasaka Y, Yasuma R, Apicella I, Pereira F, Makin RD, Magner E, Liu X, Sun J, Wang M, Baker K, Marion KM, Huang X, Baghdasaryan E, Ambati M, Ambati VL, Pandey A, Pandya L, Cummings T, Banerjee D, Huang P, Yerramothu P, Tolstonog GV, Held U, Erwin JA, Paquola ACM, Herdy JR, Ogura Y, Terasaki H, Oshika T, Darwish S, Singh RK, Mozaffari S, Bhattarai D, Kim KB, Hardin JW, Bennett CL, Hinton DR, Hanson TE, Röver C, Parang K, Kerur N, Liu J, Werner BC, Sutton SS, Sadda SR, Schumann GG, Gelfand BD, Gage FH, Ambati J. Cytoplasmic synthesis of endogenous Alu complementary DNA via reverse transcription and implications in age-related macular degeneration. Proc Natl Acad Sci U S A 2021; 118:e2022751118. [PMID: 33526699 PMCID: PMC8017980 DOI: 10.1073/pnas.2022751118] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Alu retroelements propagate via retrotransposition by hijacking long interspersed nuclear element-1 (L1) reverse transcriptase (RT) and endonuclease activities. Reverse transcription of Alu RNA into complementary DNA (cDNA) is presumed to occur exclusively in the nucleus at the genomic integration site. Whether Alu cDNA is synthesized independently of genomic integration is unknown. Alu RNA promotes retinal pigmented epithelium (RPE) death in geographic atrophy, an untreatable type of age-related macular degeneration. We report that Alu RNA-induced RPE degeneration is mediated via cytoplasmic L1-reverse-transcribed Alu cDNA independently of retrotransposition. Alu RNA did not induce cDNA production or RPE degeneration in L1-inhibited animals or human cells. Alu reverse transcription can be initiated in the cytoplasm via self-priming of Alu RNA. In four health insurance databases, use of nucleoside RT inhibitors was associated with reduced risk of developing atrophic macular degeneration (pooled adjusted hazard ratio, 0.616; 95% confidence interval, 0.493-0.770), thus identifying inhibitors of this Alu replication cycle shunt as potential therapies for a major cause of blindness.
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Affiliation(s)
- Shinichi Fukuda
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Akhil Varshney
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Benjamin J Fowler
- Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, KY 40536
| | - Shao-Bin Wang
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Siddharth Narendran
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Aravind Eye Hospital System, Madurai 625020, India
| | - Kameshwari Ambati
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Tetsuhiro Yasuma
- Department of Ophthalmology and Visual Sciences, University of Kentucky, Lexington, KY 40536
- Department of Ophthalmology, Graduate School of Medicine, Nagoya University, Nagoya 464-8601, Japan
| | - Joseph Magagnoli
- Dorn Research Institute, Columbia Veterans Affairs Health Care System, Columbia, SC 29209
- Department of Clinical Pharmacy and Outcomes Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - Hannah Leung
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Shuichiro Hirahara
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Yosuke Nagasaka
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Reo Yasuma
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, Graduate School of Medicine, Nagoya University, Nagoya 464-8601, Japan
| | - Ivana Apicella
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Felipe Pereira
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Departamento de Oftalmologia e Ciências Visuais, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo 04023-062, Brazil
| | - Ryan D Makin
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Eamonn Magner
- Department of Computer Science, University of Kentucky, Lexington, KY 40536
| | - Xinan Liu
- Department of Computer Science, University of Kentucky, Lexington, KY 40536
| | - Jian Sun
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Mo Wang
- Doheny Eye Institute, Los Angeles, CA 90033
| | | | | | - Xiwen Huang
- Department of Computer Science, University of Kentucky, Lexington, KY 40536
| | - Elmira Baghdasaryan
- Doheny Eye Institute, Los Angeles, CA 90033
- Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Meenakshi Ambati
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Center for Digital Image Evaluation, Charlottesville, VA 22901
| | - Vidya L Ambati
- Center for Digital Image Evaluation, Charlottesville, VA 22901
| | - Akshat Pandey
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Lekha Pandya
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Tammy Cummings
- Dorn Research Institute, Columbia Veterans Affairs Health Care System, Columbia, SC 29209
- Department of Clinical Pharmacy and Outcomes Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - Daipayan Banerjee
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Peirong Huang
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Praveen Yerramothu
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Genrich V Tolstonog
- Department of Otolaryngology-Head and Neck Surgery, University Hospital of Lausanne, 1011 Lausanne, Switzerland
| | - Ulrike Held
- Department of Medical Biotechnology, Paul Ehrlich Institute, 63225 Langen, Germany
| | - Jennifer A Erwin
- The Lieber Institute for Brain Development, School of Medicine, Johns Hopkins University, Baltimore, MD 21205
| | - Apua C M Paquola
- The Lieber Institute for Brain Development, School of Medicine, Johns Hopkins University, Baltimore, MD 21205
| | - Joseph R Herdy
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037
| | - Yuichiro Ogura
- Department of Ophthalmology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan
| | - Hiroko Terasaki
- Department of Ophthalmology, Graduate School of Medicine, Nagoya University, Nagoya 464-8601, Japan
| | - Tetsuro Oshika
- Department of Ophthalmology, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Shaban Darwish
- Center for Targeted Drug Delivery, Department of Biomedical and Pharmaceutical Sciences, School of Pharmacy, Chapman University, Irvine, CA 92618
- Organometallic and Organometalloid Chemistry Department, National Research Centre, Giza 12622, Egypt
| | - Ramendra K Singh
- Center for Targeted Drug Delivery, Department of Biomedical and Pharmaceutical Sciences, School of Pharmacy, Chapman University, Irvine, CA 92618
| | - Saghar Mozaffari
- Center for Targeted Drug Delivery, Department of Biomedical and Pharmaceutical Sciences, School of Pharmacy, Chapman University, Irvine, CA 92618
| | - Deepak Bhattarai
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536
| | - Kyung Bo Kim
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536
| | - James W Hardin
- Dorn Research Institute, Columbia Veterans Affairs Health Care System, Columbia, SC 29209
- Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC 29208
| | - Charles L Bennett
- Dorn Research Institute, Columbia Veterans Affairs Health Care System, Columbia, SC 29209
- Department of Clinical Pharmacy and Outcomes Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
- Center for Medication Safety and Efficacy, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - David R Hinton
- Department of Ophthalmology, University of Southern California Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Timothy E Hanson
- Medtronic, Inc., Minneapolis, MN 55432
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN 55455
| | - Christian Röver
- Department of Medical Statistics, University Medical Center Göttingen, D-37073 Göttingen, Germany
| | - Keykavous Parang
- Center for Targeted Drug Delivery, Department of Biomedical and Pharmaceutical Sciences, School of Pharmacy, Chapman University, Irvine, CA 92618
| | - Nagaraj Kerur
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Neuroscience, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Pathology, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Jinze Liu
- Department of Computer Science, University of Kentucky, Lexington, KY 40536
| | - Brian C Werner
- Department of Orthopaedic Surgery, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - S Scott Sutton
- Dorn Research Institute, Columbia Veterans Affairs Health Care System, Columbia, SC 29209
- Department of Clinical Pharmacy and Outcomes Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208
| | - Srinivas R Sadda
- Doheny Eye Institute, Los Angeles, CA 90033
- Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Gerald G Schumann
- Department of Medical Biotechnology, Paul Ehrlich Institute, 63225 Langen, Germany
| | - Bradley D Gelfand
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Biomedical Engineering, School of Medicine, University of Virginia, Charlottesville, VA 22908
| | - Fred H Gage
- Laboratory of Genetics, Salk Institute for Biological Studies, La Jolla, CA 92037;
| | - Jayakrishna Ambati
- Center for Advanced Vision Science, School of Medicine, University of Virginia, Charlottesville, VA 22908;
- Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Pathology, School of Medicine, University of Virginia, Charlottesville, VA 22908
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, Charlottesville, VA 22908
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9
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Gamdzyk M, Doycheva DM, Araujo C, Ocak U, Luo Y, Tang J, Zhang JH. cGAS/STING Pathway Activation Contributes to Delayed Neurodegeneration in Neonatal Hypoxia-Ischemia Rat Model: Possible Involvement of LINE-1. Mol Neurobiol 2020; 57:2600-2619. [PMID: 32253733 PMCID: PMC7260114 DOI: 10.1007/s12035-020-01904-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 03/19/2020] [Indexed: 12/12/2022]
Abstract
cGAS is a sensor of cytosolic DNA and responds equally to exogenous and endogenous DNA. After recognition of cytosolic dsDNA or ssDNA, cGAS synthesizes the second messenger 2'3'-cGAMP, which then binds to and activates stimulator of interferon genes (STING). STING plays an essential role in responding to pathogenic DNA and self-DNA in the context of autoimmunity. In pathologic conditions, such as stroke or hypoxia-ischemia (HI), DNA can gain access into the cytoplasm of the cell and leak from the dying cells into the extracellular environment, which potentially activates cGAS/STING. Recent in vivo studies of myocardial ischemia, traumatic brain injury, and liver damage models suggest that activation of cGAS/STING is not only a side-effect of the injury, but it can also actively contribute to cell death and apoptosis. We found, for the first time, that cGAS/STING pathway becomes activated between 24 and 48 h after HI in a 10-day-old rat model. Silencing STING with siRNA resulted in decreased infarction area, reduced cortical neurodegeneration, and improved neurobehavior at 48 h, suggesting that STING can contribute to injury progression after HI. STING colocalized with lysosomal marker LAMP-1 and blocking STING reduced the expression of cathepsin B and decreased the expression of Bax and caspase 3 cleavage. We observed similar protective effects after intranasal treatment with cGAS inhibitor RU.521, which were reversed by administration of STING agonist 2'3'-cGAMP. Additionally, we showed that long interspersed element 1 (LINE-1) retrotransposon, a potential upstream activator of cGAS/STING pathway was induced at 48 h after HI, which was evidenced by increased expression of ORF1p and ORF2p proteins and increased LINE-1 DNA content in the cytosol. Blocking LINE-1 with the nucleoside analog reverse-transcriptase inhibitor (NRTI) stavudine reduced infarction area, neuronal degeneration in the cerebral cortex, and reduced the expression of Bax and cleaved caspase 3. Thus, our results identify the cGAS/STING pathway as a potential therapeutic target to inhibit delayed neuronal death after HI.
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Affiliation(s)
- Marcin Gamdzyk
- Department of Physiology and Pharmacology, Basic Sciences, School of Medicine, Loma Linda University, 11041 Campus St, Risley Hall, Room 219, Loma Linda, CA, 92354, USA
| | - Desislava Met Doycheva
- Department of Physiology and Pharmacology, Basic Sciences, School of Medicine, Loma Linda University, 11041 Campus St, Risley Hall, Room 219, Loma Linda, CA, 92354, USA
| | - Camila Araujo
- Department of Physiology and Pharmacology, Basic Sciences, School of Medicine, Loma Linda University, 11041 Campus St, Risley Hall, Room 219, Loma Linda, CA, 92354, USA
| | - Umut Ocak
- Department of Physiology and Pharmacology, Basic Sciences, School of Medicine, Loma Linda University, 11041 Campus St, Risley Hall, Room 219, Loma Linda, CA, 92354, USA
- Department of Emergency Medicine, Bursa Yuksek Ihtisas Training and Research Hospital, University of Health Sciences, 16310, Bursa, Turkey
| | - Yujie Luo
- Department of Physiology and Pharmacology, Basic Sciences, School of Medicine, Loma Linda University, 11041 Campus St, Risley Hall, Room 219, Loma Linda, CA, 92354, USA
| | - Jiping Tang
- Department of Physiology and Pharmacology, Basic Sciences, School of Medicine, Loma Linda University, 11041 Campus St, Risley Hall, Room 219, Loma Linda, CA, 92354, USA
| | - John H Zhang
- Department of Physiology and Pharmacology, Basic Sciences, School of Medicine, Loma Linda University, 11041 Campus St, Risley Hall, Room 219, Loma Linda, CA, 92354, USA.
- Department of Anesthesiology, Neurosurgery and Neurology, Loma Linda University School of Medicine, 11041 Campus St, Risley Hall, Room 219, Loma Linda, CA, 92354, USA.
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10
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Romero MA, Mumford PW, Roberson PA, Osburn SC, Parry HA, Kavazis AN, Gladden LB, Schwartz TS, Baker BA, Toedebusch RG, Childs TE, Booth FW, Roberts MD. Five months of voluntary wheel running downregulates skeletal muscle LINE-1 gene expression in rats. Am J Physiol Cell Physiol 2019; 317:C1313-C1323. [PMID: 31618076 DOI: 10.1152/ajpcell.00301.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Transposable elements (TEs) are mobile DNA and constitute approximately half of the human genome. LINE-1 (L1) is the only active autonomous TE in the mammalian genome and has been implicated in a number of diseases as well as aging. We have previously reported that skeletal muscle L1 expression is lower following acute and chronic exercise training in humans. Herein, we used a rodent model of voluntary wheel running to determine whether long-term exercise training affects markers of skeletal muscle L1 regulation. Selectively bred high-running female Wistar rats (n = 11 per group) were either given access to a running wheel (EX) or not (SED) at 5 wk of age, and these conditions were maintained until 27 wk of age. Thereafter, mixed gastrocnemius tissue was harvested and analyzed for L1 mRNA expression and DNA content along with other L1 regulation markers. We observed significantly (P < 0.05) lower L1 mRNA expression, higher L1 DNA methylation, and less L1 DNA in accessible chromatin regions in EX versus SED rats. We followed these experiments with 3-h in vitro drug treatments in L6 myotubes to mimic transient exercise-specific signaling events. The AMP-activated protein kinase (AMPK) agonist 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR; 4 mM) significantly decreased L1 mRNA expression in L6 myotubes. However, this effect was not facilitated through increased L1 DNA methylation. Collectively, these data suggest that long-term voluntary wheel running downregulates skeletal muscle L1 mRNA, and this may occur through chromatin modifications. Enhanced AMPK signaling with repetitive exercise bouts may also decrease L1 mRNA expression, although the mechanism of action remains unknown.
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Affiliation(s)
| | | | | | | | - Hailey A Parry
- School of Kinesiology, Auburn University, Auburn, Alabama
| | | | | | - Tonia S Schwartz
- Department of Biological Sciences, Auburn University, Auburn, Alabama
| | - Brent A Baker
- National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia
| | - Ryan G Toedebusch
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Thomas E Childs
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Frank W Booth
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama.,Edward Via College of Osteopathic Medicine-Auburn Campus, Auburn, Alabama
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11
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Mumford PW, Romero MA, Osburn SC, Roberson PA, Vann CG, Mobley CB, Brown MD, Kavazis AN, Young KC, Roberts MD. Skeletal muscle LINE-1 retrotransposon activity is upregulated in older versus younger rats. Am J Physiol Regul Integr Comp Physiol 2019; 317:R397-R406. [PMID: 31188650 DOI: 10.1152/ajpregu.00110.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Long interspersed element-1 (LINE-1) is a retrotransposon capable of replicating and inserting LINE-1 copies into the genome. Others have reported skeletal muscle LINE-1 markers are higher in older versus younger mice, but data are lacking in other species. Herein, gastrocnemius muscle from male Fischer 344 rats that were 3, 12, and 24 mo old (n = 9 per group) were analyzed for LINE-1 mRNA, DNA, promoter methylation and DNA accessibility. qPCR primers were designed for active (L1.3) and inactive (L1.Tot) LINE-1 elements as well as part of the ORF1 sequence. L1.3, L1.Tot, and ORF1 mRNAs were higher (P < 0.05) in 12/24 versus 3-mo-old rats. L1.3 DNA was higher in the 24-mo-old rats versus other groups, and ORF1 DNA was greater in 12/24 versus 3-mo-old rats. ORF1 protein was higher in 12/24 versus 3-mo-old rats. RNA-sequencing indicated mRNAs related to DNA methylation (Tet1) and histone acetylation (Hdac2) were lower in 24 versus 3-mo-old rats. L1.3 DNA accessibility was higher in 24-mo-old versus 3-mo-old rats. No age-related differences in nuclear histone deacetylase (HDAC) activity existed, although nuclear DNA methyltransferase (DNMT) activity was lower in 12/24 versus 3-mo-old rats (P < 0.05). In summary, markers of skeletal muscle LINE-1 activity increase across the age spectrum of rats, and this may be related to deficits in DNMT activity and/or increased LINE-1 DNA accessibility.
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Affiliation(s)
| | | | | | | | | | - Christopher B Mobley
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky
| | | | - Andreas N Kavazis
- School of Kinesiology, Auburn University, Auburn, Alabama.,Edward Via College of Osteopathic Medicine, Auburn, Alabama
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, Alabama.,Edward Via College of Osteopathic Medicine, Auburn, Alabama
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama.,Edward Via College of Osteopathic Medicine, Auburn, Alabama
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12
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Freeman BT, Sokolowski M, Roy-Engel AM, Smither ME, Belancio VP. Identification of charged amino acids required for nuclear localization of human L1 ORF1 protein. Mob DNA 2019; 10:20. [PMID: 31080522 PMCID: PMC6501352 DOI: 10.1186/s13100-019-0159-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 04/10/2019] [Indexed: 01/10/2023] Open
Abstract
Background Long Interspersed Element 1 (LINE-1) is a retrotransposon that is present in 500,000 copies in the human genome. Along with Alu and SVA elements, these three retrotransposons account for more than a third of the human genome sequence. These mobile elements are able to copy themselves within the genome via an RNA intermediate, a process that can promote genome instability. LINE-1 encodes two proteins, ORF1p and ORF2p. Association of ORF1p, ORF2p and a full-length L1 mRNA in a ribonucleoprotein (RNP) particle, L1 RNP, is required for L1 retrotransposition. Previous studies have suggested that fusion of a tag to L1 proteins can interfere with L1 retrotransposition. Results Using antibodies detecting untagged human ORF1p, western blot analysis and manipulation of ORF1 sequence and length, we have identified a set of charged amino acids in the C-terminal region of ORF1p that are important in determining its subcellular localization. Mutation of 7 non-identical lysine residues is sufficient to make the resulting ORF1p to be predominantly cytoplasmic, demonstrating intrinsic redundancy of this requirement. These residues are also necessary for ORF1p to retain its association with KPNA2 nuclear pore protein. We demonstrate that this interaction is significantly reduced by RNase treatment. Using co-IP, we have also determined that human ORF1p associates with all members of the KPNA subfamily. Conclusions The prediction of NLS sequences suggested that specific sequences within ORF1p could be responsible for its subcellular localization by interacting with nuclear binding proteins. We have found that multiple charged amino acids in the C-terminus of ORF1p are involved in ORF1 subcellular localization and interaction with KPNA2 nuclear pore protein. Our data demonstrate that different amino acids can be mutated to have the same phenotypic effect on ORF1p subcellular localization, demonstrating that the net number of charged residues or protein structure, rather than their specific location, is important for the ORF1p nuclear localization. We also identified that human ORF1p interacts with all members of the KPNA family of proteins and that multiple KPNA family genes are expressed in human cell lines. Electronic supplementary material The online version of this article (10.1186/s13100-019-0159-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- B T Freeman
- 1Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, Tulane Center for Aging, New Orleans, LA 70112 USA
| | - M Sokolowski
- 1Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, Tulane Center for Aging, New Orleans, LA 70112 USA
| | - A M Roy-Engel
- 2Department of Epidemiology, School of Public Health and Tropical Medicine, Tulane Cancer Center, Tulane University, New Orleans, Louisiana 70112 USA
| | - M E Smither
- 1Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, Tulane Center for Aging, New Orleans, LA 70112 USA
| | - V P Belancio
- 1Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, Tulane Center for Aging, New Orleans, LA 70112 USA
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13
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Pereira GC, Sanchez L, Schaughency PM, Rubio-Roldán A, Choi JA, Planet E, Batra R, Turelli P, Trono D, Ostrow LW, Ravits J, Kazazian HH, Wheelan SJ, Heras SR, Mayer J, García-Pérez JL, Goodier JL. Properties of LINE-1 proteins and repeat element expression in the context of amyotrophic lateral sclerosis. Mob DNA 2018; 9:35. [PMID: 30564290 PMCID: PMC6295051 DOI: 10.1186/s13100-018-0138-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 11/15/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease involving loss of motor neurons and having no known cure and uncertain etiology. Several studies have drawn connections between altered retrotransposon expression and ALS. Certain features of the LINE-1 (L1) retrotransposon-encoded ORF1 protein (ORF1p) are analogous to those of neurodegeneration-associated RNA-binding proteins, including formation of cytoplasmic aggregates. In this study we explore these features and consider possible links between L1 expression and ALS. RESULTS We first considered factors that modulate aggregation and subcellular distribution of LINE-1 ORF1p, including nuclear localization. Changes to some ORF1p amino acid residues alter both retrotransposition efficiency and protein aggregation dynamics, and we found that one such polymorphism is present in endogenous L1s abundant in the human genome. We failed, however, to identify CRM1-mediated nuclear export signals in ORF1p nor strict involvement of cell cycle in endogenous ORF1p nuclear localization in human 2102Ep germline teratocarcinoma cells. Some proteins linked with ALS bind and colocalize with L1 ORF1p ribonucleoprotein particles in cytoplasmic RNA granules. Increased expression of several ALS-associated proteins, including TAR DNA Binding Protein (TDP-43), strongly limits cell culture retrotransposition, while some disease-related mutations modify these effects. Using quantitative reverse transcription PCR (RT-qPCR) of ALS tissues and reanalysis of publicly available RNA-Seq datasets, we asked if changes in expression of retrotransposons are associated with ALS. We found minimal altered expression in sporadic ALS tissues but confirmed a previous report of differential expression of many repeat subfamilies in C9orf72 gene-mutated ALS patients. CONCLUSIONS Here we extended understanding of the subcellular localization dynamics of the aggregation-prone LINE-1 ORF1p RNA-binding protein. However, we failed to find compelling evidence for misregulation of LINE-1 retrotransposons in sporadic ALS nor a clear effect of ALS-associated TDP-43 protein on L1 expression. In sum, our study reveals that the interplay of active retrotransposons and the molecular features of ALS are more complex than anticipated. Thus, the potential consequences of altered retrotransposon activity for ALS and other neurodegenerative disorders are worthy of continued investigation.
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Affiliation(s)
- Gavin C. Pereira
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Laura Sanchez
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
| | - Paul M. Schaughency
- Oncology Center-Cancer Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Alejandro Rubio-Roldán
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
| | - Jungbin A. Choi
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Evarist Planet
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Ranjan Batra
- Department of Neurosciences, School of Medicine, University of California at San Diego, San Diego, California USA
| | - Priscilla Turelli
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Didier Trono
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Lyle W. Ostrow
- Neuromuscular Division, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - John Ravits
- Department of Neurosciences, School of Medicine, University of California at San Diego, San Diego, California USA
| | - Haig H. Kazazian
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Sarah J. Wheelan
- Oncology Center-Cancer Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Sara R. Heras
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
- Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - Jens Mayer
- Department of Human Genetics, Medical Faculty, University of Saarland, Homburg/Saar, Germany
| | - Jose Luis García-Pérez
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - John L. Goodier
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
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14
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Giorgi G, Virgili M, Monti B, Del Re B. Long INterspersed nuclear Elements (LINEs) in brain and non-brain tissues of the rat. Cell Tissue Res 2018; 374:17-24. [PMID: 29725769 DOI: 10.1007/s00441-018-2843-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 04/11/2018] [Indexed: 10/17/2022]
Abstract
Long INterspersed Element-1 (L1) is a transposable element that can insert copies of itself in new genomic locations causing genomic instability. In somatic cells, L1 retrotransposition activity is usually repressed but somatic L1 retrotransposition has recently been observed during neuronal differentiation. In this study, we evaluate whether L1 elements are differentially active in rat tissues during postnatal development. To this purpose, we quantified L1 in genomic DNA extracted from the olfactory bulb (OB), cerebellum (CE), cortex (CO) and heart (H). Each analysis was repeated on rats aged 7, 21 and 60 days. We found that L1 content in OB and CE tissue was significantly higher than H tissue, in rats of all three ages studied, suggesting that L1 activity could be modulated in postnatal development and neurogenesis.
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Affiliation(s)
- Gianfranco Giorgi
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Marco Virgili
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Barbara Monti
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Brunella Del Re
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, via Selmi 3, 40126, Bologna, Italy.
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15
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Rytömaa T, Grip-Rytömaa K. Spontaneous death of rat chloroleukaemia cells induced by an endogenous growth inhibitor. Cell Prolif 2018; 51. [PMID: 29226462 PMCID: PMC6528872 DOI: 10.1111/cpr.12421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/28/2017] [Indexed: 01/31/2023] Open
Abstract
OBJECTIVES When rat chloroleukaemia (CHL) cells are grown undisturbed in a confined space, a genomic long interspersed nuclear element (LINE) is transcriptionally activated at a relatively low population density, followed by the retrotransposition of LINE and population death. This death programme is fundamentally different from conventional cell death pathways. MATERIALS AND METHODS This work is essentially based on the re-analysis of relevant, old experimental data. Elemental analysis of a highly purified, long-stored inhibitor sample was performed. Genomic sequence searches were performed using the basic local alignment search tool (BLAST). RESULTS This death programme is initiated by an endogenous inhibitor secreted by CHL cells. The inhibitor is almost certainly identical to the pentapeptide pyroGlu-Glu-Asp-Cys-Lys, shown to be a cell line-specific inhibitor of normal granulocytic cells. The inhibitor is derived from a highly conserved short open reading frame in mammalian genomes. CONCLUSIONS Although spontaneous population death may be a biological oddity restricted to rat CHL cells, we suggest that this death programme is responsible for the eradication of cancer cells following treatment with an inhibitor administered exogenously.
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Affiliation(s)
- T Rytömaa
- Finnish Medical Society Duodecim, Helsinki, Finland
- Finnish Society of Radiobiology, Helsinki, Finland
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16
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Romero MA, Mobley CB, Mumford PW, Roberson PA, Haun CT, Kephart WC, Healy JC, Beck DT, Young KC, Martin JS, Lockwood CM, Roberts MD. Acute and chronic resistance training downregulates select LINE-1 retrotransposon activity markers in human skeletal muscle. Am J Physiol Cell Physiol 2017; 314:C379-C388. [PMID: 29351416 DOI: 10.1152/ajpcell.00192.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Herein, we examined if acute or chronic resistance exercise affected markers of skeletal muscle long interspersed nuclear element-1 (LINE-1) retrotransposon activity. In study 1, 10 resistance-trained college-aged men performed three consecutive daily back squat sessions, and vastus lateralis biopsies were taken before (Pre), 2 h following session 1 (Post1), and 3 days following session 3 (Post2). In study 2, 13 untrained college-aged men performed a full-body resistance training program (3 days/wk), and vastus lateralis biopsies were taken before ( week 0) and ~72 h following training cessation ( week 12). In study 1, LINE-1 mRNA decreased 42-48% at Post1 and 2 ( P < 0.05), and reverse transcriptase (RT) activity trended downward at Post2 (-37%, P = 0.067). In study 2, LINE-1 mRNA trended downward at week 12 (-17%, P = 0.056) while LINE-1 promoter methylation increased (+142%, P = 0.041). Open reading frame (ORF)2p protein expression (-24%, P = 0.059) and RT activity (-26%, P = 0.063) also trended downward by week 12. Additionally, changes in RT activity versus satellite cell number were inversely associated ( r = -0.725, P = 0.008). Follow-up in vitro experiments demonstrated that 48-h treatments with lower doses (1 μM and 10 μM) of efavirenz and nevirapine (non-nucleoside RT inhibitors) increased myoblast proliferation ( P < 0.05). However, we observed a paradoxical decrease in myoblast proliferation with higher doses (50 μM) of efavirenz and delavirdine. This is the first report suggesting that resistance exercise downregulates markers of skeletal muscle LINE-1 activity. Given our discordant in vitro findings, future research is needed to thoroughly assess whether LINE-1-mediated RT activity enhances or blunts myoblast, or primary satellite cell, proliferative capacity.
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Affiliation(s)
| | | | | | | | - Cody T Haun
- School of Kinesiology, Auburn University , Auburn, Alabama
| | | | - James C Healy
- School of Kinesiology, Auburn University , Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus , Auburn, Alabama
| | - Darren T Beck
- School of Kinesiology, Auburn University , Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus , Auburn, Alabama
| | - Kaelin C Young
- School of Kinesiology, Auburn University , Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus , Auburn, Alabama
| | - Jeffrey S Martin
- School of Kinesiology, Auburn University , Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus , Auburn, Alabama
| | | | - Michael D Roberts
- School of Kinesiology, Auburn University , Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus , Auburn, Alabama
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17
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Sur D, Kustwar RK, Budania S, Mahadevan A, Hancks DC, Yadav V, Shankar SK, Mandal PK. Detection of the LINE-1 retrotransposon RNA-binding protein ORF1p in different anatomical regions of the human brain. Mob DNA 2017; 8:17. [PMID: 29201157 PMCID: PMC5700708 DOI: 10.1186/s13100-017-0101-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 11/14/2017] [Indexed: 12/27/2022] Open
Abstract
Background Recent reports indicate that retrotransposons – a type of mobile DNA – can contribute to neuronal genetic diversity in mammals. Retrotransposons are genetic elements that mobilize via an RNA intermediate by a “copy-and-paste” mechanism termed retrotransposition. Long Interspersed Element-1 (LINE-1 or L1) is the only active autonomous retrotransposon in humans and its activity is responsible for ~ 30% of genomic mass. Historically, L1 retrotransposition was thought to be restricted to the germline; however, new data indicate L1 s are active in somatic tissue with certain regions of the brain being highly permissive. The functional implications of L1 insertional activity in the brain and how host cells regulate it are incomplete. While deep sequencing and qPCR analysis have shown that L1 copy number is much higher in certain parts of the human brain, direct in vivo studies regarding detection of L1-encoded proteins is lacking due to ineffective reagents. Results Using a polyclonal antibody we generated against the RNA-binding (RRM) domain of L1 ORF1p, we observe widespread ORF1p expression in post-mortem human brain samples including the hippocampus which has known elevated rates of retrotransposition. In addition, we find that two brains from different individuals of different ages display very different expression of ORF1p, especially in the frontal cortex. Conclusions We hypothesize that discordance of ORF1p expression in parts of the brain reported to display elevated levels of retrotransposition may suggest the existence of factors mediating post-translational regulation of L1 activity in the human brain. Furthermore, this antibody reagent will be useful as a complementary means to confirm findings related to retrotransposon biology and activity in the brain and other tissues in vivo. Electronic supplementary material The online version of this article (10.1186/s13100-017-0101-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Debpali Sur
- Department of Biotechnology, IIT Roorkee, Roorkee, Uttarakhand India
| | | | - Savita Budania
- Department of Biotechnology, IIT Roorkee, Roorkee, Uttarakhand India
| | - Anita Mahadevan
- Human Brain Tissue Repository (HBTR), Neurobiology Research Centre, NIMHANS, Bangalore, 560 029 India
| | - Dustin C Hancks
- Department of Human Genetics, University of Utah, Salt Lake City, UT USA.,Present address: Department of Immunology, UT South-western Medical Centre, Dallas, TX USA
| | - Vijay Yadav
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
| | - S K Shankar
- Human Brain Tissue Repository (HBTR), Neurobiology Research Centre, NIMHANS, Bangalore, 560 029 India
| | - Prabhat K Mandal
- Department of Biotechnology, IIT Roorkee, Roorkee, Uttarakhand India
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18
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Dong Y, Huang Z, Kuang Q, Wen Z, Liu Z, Li Y, Yang Y, Li M. Expression dynamics and relations with nearby genes of rat transposable elements across 11 organs, 4 developmental stages and both sexes. BMC Genomics 2017; 18:666. [PMID: 28851270 PMCID: PMC5576108 DOI: 10.1186/s12864-017-4078-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 08/21/2017] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND TEs pervade mammalian genomes. However, compared with mice, fewer studies have focused on the TE expression patterns in rat, particularly the comparisons across different organs, developmental stages and sexes. In addition, TEs can influence the expression of nearby genes. The temporal and spatial influences of TEs remain unclear yet. RESULTS To evaluate the TEs transcription patterns, we profiled their transcript levels in 11 organs for both sexes across four developmental stages of rat. The results show that most short interspersed elements (SINEs) are commonly expressed in all conditions, which are also the major TE types with commonly expression patterns. In contrast, long terminal repeats (LTRs) are more likely to exhibit specific expression patterns. The expression tendency of TEs and genes are similar in most cases. For example, few specific genes and TEs are in the liver, muscle and heart. However, TEs perform superior over genes on classing organ, which imply their higher organ specificity than genes. By associating the TEs with the closest genes in genome, we find their expression levels are correlated, independent of their distance in some cases. CONCLUSIONS TEs sex-dependently associate with nearest genes. A gene would be associated with more than one TE. Our works can help to functionally annotate the genome and further understand the role of TEs in gene regulation.
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Affiliation(s)
- Yongcheng Dong
- College of Life Science, Sichuan University, Chengdu, 610064, China
| | - Ziyan Huang
- College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Qifan Kuang
- College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Zhining Wen
- College of Chemistry, Sichuan University, Chengdu, 610064, China
| | - Zhibin Liu
- College of Life Science, Sichuan University, Chengdu, 610064, China
| | - Yizhou Li
- College of Chemistry, Sichuan University, Chengdu, 610064, China.
| | - Yi Yang
- College of Life Science, Sichuan University, Chengdu, 610064, China.
| | - Menglong Li
- College of Chemistry, Sichuan University, Chengdu, 610064, China
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19
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Vieira-da-Silva A, Adega F, Guedes-Pinto H, Chaves R. LINE-1 distribution in six rodent genomes follow a species-specific pattern. J Genet 2016; 95:21-33. [PMID: 27019429 DOI: 10.1007/s12041-015-0595-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
L1 distribution in mammal's genomes is yet a huge riddle. However, these repetitive sequences were already found in all chromosomic regions, and in general, they seem to be nonrandomly distributed in the genome. It also seems that after insertion and when they are not deleterious, they are always involved in dynamic processes occurring on that particular chromosomic region. Furthermore, it seems that large-scale genome rearrangements and L1 activity and accumulation are somehow interconnected. In the present study, we analysed L1 genomic distribution in Tatera gambiana (Muridae, Gerbillinae), Acomys sp. (Muridae, Deomyinae), Cricetomys sp. (Nesomyidae, Cricetomyinae), Microtus arvalis (Cricetidae, Arvicolinae), Phodopus roborovskii and P. sungorus (Cricetidae, Cricetinae). All the species studied here seems to exhibit a species-specific pattern.Possible mechanisms, and processes involved in L1 distribution and preferential accumulation in certain regions are di scussed.
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Affiliation(s)
- A Vieira-da-Silva
- Department of Genetics and Biotechnology (DGB), Laboratory of Cytogenomics and Animal Genomics (CAG), University of Trάs-os-Montes and Alto Douro (UTAD), 5001, 801 Vila Real,
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20
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De Luca C, Guadagni F, Sinibaldi-Vallebona P, Sentinelli S, Gallucci M, Hoffmann A, Schumann GG, Spadafora C, Sciamanna I. Enhanced expression of LINE-1-encoded ORF2 protein in early stages of colon and prostate transformation. Oncotarget 2016; 7:4048-61. [PMID: 26716650 PMCID: PMC4826189 DOI: 10.18632/oncotarget.6767] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 11/30/2015] [Indexed: 12/11/2022] Open
Abstract
LINE-1 (L1) retrotransposons are a source of endogenous reverse transcriptase (RT) activity, which is expressed as part of the L1-encoded ORF2 protein (L1-ORF2p). L1 elements are highly expressed in many cancer types, while being silenced in most differentiated somatic tissues. We previously found that RT inhibition reduces cell proliferation and promotes differentiation in neoplastic cells, indicating that high endogenous RT activity promotes cancer growth. Here we investigate the expression of L1-ORF2p in several human types of cancer. We have developed a highly specific monoclonal antibody (mAb chA1-L1) to study ORF2p expression and localization in human cancer cells and tissues. We uncover new evidence for high levels of L1-ORF2p in transformed cell lines and staged epithelial cancer tissues (colon, prostate, lung and breast) while no or only basal ORF2p expression was detected in non-transformed cells. An in-depth analysis of colon and prostate tissues shows ORF2p expression in preneoplastic stages, namely transitional mucosa and prostate intraepithelial neoplasia (PIN), respectively. Our results show that L1-ORF2p is overexpressed in tumor and in preneoplastic colon and prostate tissues; this latter finding suggests that ORF2p could be considered as a potential early diagnostic biomarker.
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Affiliation(s)
| | - Fiorella Guadagni
- Laboratory BioDAT SR Research, IRCCS San Raffaele Pisana, Rome, Italy
| | - Paola Sinibaldi-Vallebona
- Department of Experimental Medicine and Surgery, University "Tor Vergata", Rome, Italy.,Institute of Translational Pharmacology, CNR, Rome, Italy
| | - Steno Sentinelli
- I.F.O. Regina Elena, UOC Pathological Anatomy/Urology, Rome, Italy
| | - Michele Gallucci
- I.F.O. Regina Elena, UOC Pathological Anatomy/Urology, Rome, Italy
| | - Andreas Hoffmann
- Department of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
| | - Gerald G Schumann
- Department of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
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21
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Meyer TJ, Held U, Nevonen KA, Klawitter S, Pirzer T, Carbone L, Schumann GG. The Flow of the Gibbon LAVA Element Is Facilitated by the LINE-1 Retrotransposition Machinery. Genome Biol Evol 2016; 8:3209-3225. [PMID: 27635049 PMCID: PMC5174737 DOI: 10.1093/gbe/evw224] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
LINE-Alu-VNTR-Alu-like (LAVA) elements comprise a family of non-autonomous, composite, non-LTR retrotransposons specific to gibbons and may have played a role in the evolution of this lineage. A full-length LAVA element consists of portions of repeats found in most primate genomes: CT-rich, Alu-like, and VNTR regions from the SVA retrotransposon, and portions of the AluSz and L1ME5 elements. To evaluate whether the gibbon genome currently harbors functional LAVA elements capable of mobilization by the endogenous LINE-1 (L1) protein machinery and which LAVA components are important for retrotransposition, we established a trans-mobilization assay in HeLa cells. Specifically, we tested if a full-length member of the older LAVA subfamily C that was isolated from the gibbon genome and named LAVAC, or its components, can be mobilized in the presence of the human L1 protein machinery. We show that L1 proteins mobilize the LAVAC element at frequencies exceeding processed pseudogene formation and human SVAE retrotransposition by > 100-fold and ≥3-fold, respectively. We find that only the SVA-derived portions confer activity, and truncation of the 3′ L1ME5 portion increases retrotransposition rates by at least 100%. Tagged de novo insertions integrated into intronic regions in cell culture, recapitulating findings in the gibbon genome. Finally, we present alternative models for the rise of the LAVA retrotransposon in the gibbon lineage.
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Affiliation(s)
- Thomas J Meyer
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon
- Division of Bioinformatics and Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Oregon Health & Science University, Portland, Oregon
| | - Ulrike Held
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
| | - Kimberly A Nevonen
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon
| | - Sabine Klawitter
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
- Present address: Division of Inborn Metabolic Diseases, University Children's Hospital, Heidelberg, Germany
| | - Thomas Pirzer
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
| | - Lucia Carbone
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, Oregon
- Division of Bioinformatics and Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Oregon Health & Science University, Portland, Oregon
- Department of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Gerald G Schumann
- Division of Medical Biotechnology, Paul-Ehrlich-Institut, Langen, Germany
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22
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Kemp JR, Longworth MS. Crossing the LINE Toward Genomic Instability: LINE-1 Retrotransposition in Cancer. Front Chem 2015; 3:68. [PMID: 26734601 PMCID: PMC4679865 DOI: 10.3389/fchem.2015.00068] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/27/2015] [Indexed: 12/17/2022] Open
Abstract
Retrotransposons are repetitive DNA sequences that are positioned throughout the human genome. Retrotransposons are capable of copying themselves and mobilizing new copies to novel genomic locations in a process called retrotransposition. While most retrotransposon sequences in the human genome are incomplete and incapable of mobilization, the LINE-1 retrotransposon, which comprises~17% of the human genome, remains active. The disruption of cellular mechanisms that suppress retrotransposon activity is linked to the generation of aneuploidy, a potential driver of tumor development. When retrotransposons insert into a novel genomic region, they have the potential to disrupt the coding sequence of endogenous genes and alter gene expression, which can lead to deleterious consequences for the organism. Additionally, increased LINE-1 copy numbers provide more chances for recombination events to occur between retrotransposons, which can lead to chromosomal breaks and rearrangements. LINE-1 activity is increased in various cancer cell lines and in patient tissues resected from primary tumors. LINE-1 activity also correlates with increased cancer metastasis. This review aims to give a brief overview of the connections between LINE-1 retrotransposition and the loss of genome stability. We will also discuss the mechanisms that repress retrotransposition in human cells and their links to cancer.
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Affiliation(s)
- Jacqueline R Kemp
- Department of Cellular and Molecular Medicine, Lerner Research Institute of Cleveland Clinic Cleveland, OH, USA
| | - Michelle S Longworth
- Department of Cellular and Molecular Medicine, Lerner Research Institute of Cleveland Clinic Cleveland, OH, USA
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23
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Luo YB, Zhang L, Lin ZL, Ma JY, Jia J, Namgoong S, Sun QY. Distinct subcellular localization and potential role of LINE1-ORF1P in meiotic oocytes. Histochem Cell Biol 2015; 145:93-104. [PMID: 26464247 DOI: 10.1007/s00418-015-1369-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2015] [Indexed: 02/06/2023]
Abstract
LINE-1 is an autonomous non-LTR retrotransposon in mammalian genomes and encodes ORF1P and ORF2P. ORF2P has been clearly identified as the enzyme supplier needed in LINE-1 retrotransposition. However, the role of ORF1P is not well explored. In this study, we employed loss/gain-of-function approach to investigate the role of LINE1-ORF1P in mouse oocyte meiotic maturation. During mouse oocyte development, ORF1P was observed in cytoplasm as well as in nucleus at germinal vesicle (GV) stage while was localized on the spindle after germinal vesicle breakdown (GVBD). Depletion of ORF1P caused oocyte arrest at the GV stage as well as down-regulation of CDC2 and CYCLIN B1, components of the maturation-promoting factor (MPF). Further analysis demonstrated ORF1P depletion triggered DNA damage response and most of the oocytes presented altered chromatin configuration. In addition, SMAD4 showed nuclear foci signal after Orf1p dsRNA injection. ORF1P overexpression held the oocyte development at MI stage and the chromosome alignment and spindle organization were severely affected. We also found that ORF1P could form DCP1A body-like foci structure in both cytoplasm and nucleus after heat shock. Taken together, accurate regulation of ORF1P plays an essential role in mouse oocyte meiotic maturation.
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Affiliation(s)
- Yi-Bo Luo
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Beijing, China.,Department of Animal Science, Chungbuk National University, Cheongju, Korea
| | - Li Zhang
- Hebei Key Laboratory of Animal Science, Hebei Medical University, Shijiazhuang, China
| | - Zi-Li Lin
- Department of Animal Science, Chungbuk National University, Cheongju, Korea
| | - Jun-Yu Ma
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Beijing, China
| | - Jialin Jia
- Department of Animal Science, Chungbuk National University, Cheongju, Korea
| | - Suk Namgoong
- Department of Animal Science, Chungbuk National University, Cheongju, Korea
| | - Qing-Yuan Sun
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Beijing, China.
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24
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Mobilization of LINE-1 in irradiated mammary gland tissue may potentially contribute to low dose radiation-induced genomic instability. Genes Cancer 2015; 6:71-81. [PMID: 25821563 PMCID: PMC4362486 DOI: 10.18632/genesandcancer.50] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 02/13/2015] [Indexed: 12/15/2022] Open
Abstract
It is known that cellular stresses such as ionizing radiation activate LINE-1 (long interspersed nuclear element type 1, L1), but the molecular mechanisms of LINE-1 activation have not been fully elucidated. There is a possibility that DNA methylation changes induced by genotoxic stresses might contribute to LINE-1 activation in mammalian cells. L1 insertions usually cause major genomic rearrangements, such as deletions, transductions, the intrachromosomal homologous recombination between L1s, and the generation of pseudogenes, which could lead to genomic instability. The purpose of this study was to evaluate the effects of low and high doses of ionizing radiation on the DNA methylation status of LINE-1 transposable elements in rat mammary glands. Here we describe radiation-induced hypomethylation and activation of LINE-1 ORF1 in rat mammary gland tissues. We show that radiation exposure has also led to the translation of the LINE-1 element, whereby the 148 kDa LINE-1 protein level was increased 96 hours after treatment with a low dose and low energy level radiation and remained elevated for 24 weeks after treatment. The mobilization of LINE-1 in irradiated tissue may potentially contribute to genomic instability. The observed activation of mobile elements in response to radiation exposure is consistently discussed as a plausible mechanism of cancer etiology and development.
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25
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Ianc B, Ochis C, Persch R, Popescu O, Damert A. Hominoid composite non-LTR retrotransposons-variety, assembly, evolution, and structural determinants of mobilization. Mol Biol Evol 2014; 31:2847-64. [PMID: 25216663 DOI: 10.1093/molbev/mst256] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
SVA (SINE-R-VNTR-Alu) elements constitute the youngest family of composite non-LTR retrotransposons in hominoid primates. The sequence of their assembly, however, remains unclear. Recently, a second family of VNTR-containing composites, LAVA (L1-Alu-VNTR-Alu), has been identified in gibbons. We now report the existence of two additional VNTR composite families, PVA (PTGR2-VNTR-Alu) and FVA (FRAM-VNTR-Alu), in the genome of Nomascus leucogenys. Like LAVA, they share the 5'-Alu-like region and VNTR with SVA, but differ at their 3'-ends. The 3'-end of PVA comprises part of the PTGR2 gene, whereas FVA is characterized by the presence of a partial FRAM element in its 3'-domain. Splicing could be identified as the mechanism of acquisition of the variant 3'-ends in all four families of VNTR composites. SVAs have been shown to be mobilized by the L1 protein machinery in trans. A critical role in this process has been ascribed to their 5'-hexameric repeat/ Alu-like region. The Alu-like region displays specific features in each of the VNTR composite families/subfamilies with characteristic deletions found in the evolutionary younger subfamilies. Using reciprocal exchanges between SVA_E and PVA/FVA elements, we demonstrate that the structure, not the presence of the (CCCTCT)n/ Alu-like region determines mobilization capacity. Combination of LAVA and SVA_E domains does not yield any active elements-suggesting the use of different combinations of host factors for the two major groups of VNTR composites. Finally, we demonstrate that the LAVA 3'-L1ME5 fragment attenuates mobilization capacity.
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Affiliation(s)
- Bianca Ianc
- Institute for Interdisciplinary Research in Bio-Nano-Sciences, Molecular Biology Center, Babes-Bolyai-University, Cluj-Napoca, Romania
| | - Cornelia Ochis
- Institute for Interdisciplinary Research in Bio-Nano-Sciences, Molecular Biology Center, Babes-Bolyai-University, Cluj-Napoca, Romania
| | | | - Octavian Popescu
- Institute for Interdisciplinary Research in Bio-Nano-Sciences, Molecular Biology Center, Babes-Bolyai-University, Cluj-Napoca, Romania Institute of Biology, Romanian Academy, Bucharest, Romania
| | - Annette Damert
- Institute for Interdisciplinary Research in Bio-Nano-Sciences, Molecular Biology Center, Babes-Bolyai-University, Cluj-Napoca, Romania
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26
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Dai L, LaCava J, Taylor MS, Boeke JD. Expression and detection of LINE-1 ORF-encoded proteins. Mob Genet Elements 2014; 4:e29319. [PMID: 25054082 PMCID: PMC4091050 DOI: 10.4161/mge.29319] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/19/2014] [Accepted: 05/22/2014] [Indexed: 11/30/2022] Open
Abstract
LINE-1 (L1) elements are endogenous retrotransposons active in mammalian genomes. The L1 RNA is bicistronic, encoding two non-overlapping open reading frames, ORF1 and ORF2, whose protein products (ORF1p and ORF2p) bind the L1 RNA to form a ribonucleoprotein (RNP) complex that is presumed to be a critical retrotransposition intermediate. However, ORF2p is expressed at a significantly lower level than ORF1p; these differences are thought to be controlled at the level of translation, due to a low frequency ribosome reinitiation mechanism controlling ORF2 expression. As a result, while ORF1p is readily detectable, ORF2p has previously been very challenging to detect in vitro and in vivo. To address this, we recently tested several epitope tags fused to the N- or C-termini of the ORF proteins in an effort to enable robust detection and affinity purification from native (L1RP) and synthetic (ORFeus-Hs) L1 constructs. An analysis of tagged RNPs from both L1RP and ORFeus-Hs showed similar host-cell-derived protein interactors. Our observations also revealed that the tag sequences affected the retrotransposition competency of native and synthetic L1s differently although they encode identical ORF proteins. Unexpectedly, we observed apparently stochastic expression of ORF2p within seemingly homogenous L1-expressing cell populations.
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Affiliation(s)
- Lixin Dai
- High Throughput Biology Center and Department of Molecular Biology and Genetics; Johns Hopkins University School of Medicine; Baltimore, MD USA
| | - John LaCava
- Laboratory of Cellular and Structural Biology; The Rockefeller University; New York, NY USA
| | - Martin S Taylor
- High Throughput Biology Center and Department of Pharmacology and Molecular Sciences; Johns Hopkins University School of Medicine; Baltimore, MD USA
| | - Jef D Boeke
- Institute for Systems Genetics; New York University School of Medicine; New York, NY USA
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27
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Belan E. LINEs of evidence: noncanonical DNA replication as an epigenetic determinant. Biol Direct 2013; 8:22. [PMID: 24034780 PMCID: PMC3868326 DOI: 10.1186/1745-6150-8-22] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 09/06/2013] [Indexed: 12/17/2022] Open
Abstract
LINE-1 (L1) retrotransposons are repetitive elements in mammalian genomes. They are
capable of synthesizing DNA on their own RNA templates by harnessing reverse
transcriptase (RT) that they encode. Abundantly expressed full-length L1s and their
RT are found to globally influence gene expression profiles, differentiation state,
and proliferation capacity of early embryos and many types of cancer, albeit by yet
unknown mechanisms. They are essential for the progression of early development and
the establishment of a cancer-related undifferentiated state. This raises important
questions regarding the functional significance of L1 RT in these cell systems.
Massive nuclear L1-linked reverse transcription has been shown to occur in mouse
zygotes and two-cell embryos, and this phenomenon is purported to be DNA replication
independent. This review argues against this claim with the goal of understanding the
nature of this phenomenon and the role of L1 RT in early embryos and cancers.
Available L1 data are revisited and integrated with relevant findings accumulated in
the fields of replication timing, chromatin organization, and epigenetics, bringing
together evidence that strongly supports two new concepts. First, noncanonical
replication of a portion of genomic full-length L1s by means of L1 RNP-driven reverse
transcription is proposed to co-exist with DNA polymerase-dependent replication of
the rest of the genome during the same round of DNA replication in embryonic and
cancer cell systems. Second, the role of this mechanism is thought to be epigenetic;
it might promote transcriptional competence of neighboring genes linked to
undifferentiated states through the prevention of tethering of involved L1s to the
nuclear periphery. From the standpoint of these concepts, several hitherto
inexplicable phenomena can be explained. Testing methods for the model are
proposed.
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Affiliation(s)
- Ekaterina Belan
- Genetics Laboratory, Royal University Hospital, Saskatoon, SK S7N 0W8, Canada.
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28
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Singh DK, Rath PC. Long interspersed nuclear elements (LINEs) show tissue-specific, mosaic genome and methylation-unrestricted, widespread expression of noncoding RNAs in somatic tissues of the rat. RNA Biol 2012; 9:1380-96. [PMID: 23064113 DOI: 10.4161/rna.22402] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We report strong somatic and germ line expression of LINE RNAs in eight different tissues of rat by using a novel ~2.8 kb genomic PstI-LINE DNA (P1-LINE) isolated from the rat brain. P1-LINE is present in a 93 kb LINE-SINE-cluster in sub-telomeric region of chromosome 12 (12p12) and as multiple truncated copies interspersed in all rat chromosomes. P1-LINEs occur as inverted repeats at multiple genomic loci in tissue-specific and mosaic patterns. P1-LINE RNAs are strongly expressed in brain, liver, lungs, heart, kidney, testes, spleen and thymus into large to small heterogeneous RNAs (~5.0 to 0.2 kb) in tissue-specific and dynamic patterns in individual rats. P1-LINE DNA is strongly methylated at CpG-dinucleotides in most genomic copies in all the tissues and weakly hypomethylated in few copies in some tissues. Small (700-75 nt) P1-LINE RNAs expressed in all tissues may be possible precursors for small regulatory RNAs (PIWI-interacting/piRNAs) bioinformatically derived from P1-LINE. The strong and dynamic expression of LINE RNAs from multiple chromosomal loci and the putative piRNAs in somatic tissues of rat under normal physiological conditions may define functional chromosomal domains marked by LINE RNAs as long noncoding RNAs (lncRNAs) unrestricted by DNA methylation. The tissue-specific, dynamic RNA expression and mosaic genomic distribution of LINEs representing a steady-state genomic flux of retrotransposon RNAs suggest for biological role of LINE RNAs as long ncRNAs and small piRNAs in mammalian tissues independent of their cellular fate for translation, reverse-transcription and retrotransposition. This may provide evolutionary advantages to LINEs and mammalian genomes.
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Affiliation(s)
- Deepak K Singh
- Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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29
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Banaz-Yaşar F, Gedik N, Karahan S, Diaz-Carballo D, Bongartz BM, Ergün S. LINE-1 retrotransposition events regulate gene expression after X-ray irradiation. DNA Cell Biol 2012; 31:1458-67. [PMID: 22845795 DOI: 10.1089/dna.2012.1676] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Long interspersed nuclear element-1 (LINE-1) retrotransposons are mobile elements that insert into new genomic locations via reverse transcription of an RNA intermediate. The mechanism of retrotransposition is not entirely understood. The integration of these elements occurs by target-primed reverse transcription (TPRT), which initiates double-strand breaks (DSBs) during the LINE-1 integration. Also, X-ray is known to induce DNA damage. The aim of this study was to evaluate the potential effects of LINE-1 de novo retrotransposition on the expression of different genes after X-ray irradiation in human endothelial cells. After stable transfection of the human hybrid endothelial cell line EA.hy926 with the human LINE-1 element, we analyzed the expression of different genes after irradiation with 5 Gy X-rays by reverse transcription-polymerase chain reaction (RT-PCR). We determine the expression level of phosphorylated p53 and γ-histone H2AX protein levels upon X-ray irradiation with 5 Gy for 24 h. Our results showed that EA.hy926 LINE-1 cell clones react with a strong upregulation of phosphorylated p53 protein, already 15 min after irradiation compared to the wild type (WT) cells. Also, the expression of γ-histone H2AX protein was elevated in the cell clones with retrotransposition events 15 min after irradiation, whereas the WT cells have a delayed expression of phosphorylated histone H2AX protein. Taken together, our findings provide that LINE-1 retrotransposition events regulate different gene expression after irradiation in the EA.hy926 cell line.
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Abstract
Transposons are DNA sequences capable of moving in genomes. Early evidence showed their accumulation in many species and suggested their continued activity in at least isolated organisms. In the past decade, with the development of various genomic technologies, it has become abundantly clear that ongoing activity is the rule rather than the exception. Active transposons of various classes are observed throughout plants and animals, including humans. They continue to create new insertions, have an enormous variety of structural and functional impact on genes and genomes, and play important roles in genome evolution. Transposon activities have been identified and measured by employing various strategies. Here, we summarize evidence of current transposon activity in various plant and animal genomes.
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Affiliation(s)
- Cheng Ran Lisa Huang
- Institute of Genetic Medicine and High Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Kathleen H. Burns
- Department of Pathology, Department of Oncology, and High Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Jef D. Boeke
- Molecular Biology and Genetics, Institute of Genetic Medicine, and High Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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31
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Rosser JM, An W. L1 expression and regulation in humans and rodents. Front Biosci (Elite Ed) 2012; 4:2203-25. [PMID: 22202032 DOI: 10.2741/537] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Long interspersed elements type 1 (LINE-1s, or L1s) have impacted mammalian genomes at multiple levels. L1 transcription is mainly controlled by its 5' untranslated region (5'UTR), which differs significantly among active human and rodent L1 families. In this review, L1 expression and its regulation are examined in the context of human and rodent development. First, endogenous L1 expression patterns in three different species-human, rat, and mouse-are compared and contrasted. A detailed account of relevant experimental evidence is presented according to the source material, such as cell lines, tumors, and normal somatic and germline tissues from different developmental stages. Second, factors involved in the regulation of L1 expression at both transcriptional and posttranscriptional levels are discussed. These include transcription factors, DNA methylation, PIWI-interacting RNAs (piRNAs), RNA interference (RNAi), and posttranscriptional host factors. Similarities and differences between human and rodent L1s are highlighted. Third, recent findings from transgenic mouse models of L1 are summarized and contrasted with those from endogenous L1 studies. Finally, the challenges and opportunities for L1 mouse models are discussed.
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Affiliation(s)
- James M Rosser
- School of Molecular Biosciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
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32
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Raiz J, Damert A, Chira S, Held U, Klawitter S, Hamdorf M, Löwer J, Strätling WH, Löwer R, Schumann GG. The non-autonomous retrotransposon SVA is trans-mobilized by the human LINE-1 protein machinery. Nucleic Acids Res 2011; 40:1666-83. [PMID: 22053090 PMCID: PMC3287187 DOI: 10.1093/nar/gkr863] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
SINE-VNTR-Alu (SVA) elements are non-autonomous, hominid-specific non-LTR retrotransposons and distinguished by their organization as composite mobile elements. They represent the evolutionarily youngest, currently active family of human non-LTR retrotransposons, and sporadically generate disease-causing insertions. Since preexisting, genomic SVA sequences are characterized by structural hallmarks of Long Interspersed Elements 1 (LINE-1, L1)-mediated retrotransposition, it has been hypothesized for several years that SVA elements are mobilized by the L1 protein machinery in trans. To test this hypothesis, we developed an SVA retrotransposition reporter assay in cell culture using three different human-specific SVA reporter elements. We demonstrate that SVA elements are mobilized in HeLa cells only in the presence of both L1-encoded proteins, ORF1p and ORF2p. SVA trans-mobilization rates exceeded pseudogene formation frequencies by 12- to 300-fold in HeLa-HA cells, indicating that SVA elements represent a preferred substrate for L1 proteins. Acquisition of an AluSp element increased the trans-mobilization frequency of the SVA reporter element by ~25-fold. Deletion of (CCCTCT)n repeats and Alu-like region of a canonical SVA reporter element caused significant attenuation of the SVA trans-mobilization rate. SVA de novo insertions were predominantly full-length, occurred preferentially in G+C-rich regions, and displayed all features of L1-mediated retrotransposition which are also observed in preexisting genomic SVA insertions.
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Affiliation(s)
- Julija Raiz
- Section PR2/Retroelements, Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany
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33
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Banaz-Yaşar F, Steffen G, Hauschild J, Bongartz BM, Schumann GG, Ergün S. LINE-1 retrotransposition events affect endothelial proliferation and migration. Histochem Cell Biol 2010; 134:581-9. [PMID: 21069374 DOI: 10.1007/s00418-010-0758-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2010] [Indexed: 10/18/2022]
Abstract
Long interspersed nuclear element-1 (LINE-1, L1) is a retrotransposon which affects the human genome by a variety of mechanisms. While LINE-1 expression is suppressed in the most somatic human cells, LINE-1 elements are activated in human cancer. Recently, high accumulation of LINE-1-encoded ORF1p and ORF2p in endothelial cells of mature human blood vessels was described. Here, we demonstrate that LINE-1 de novo retrotransposition events lead to a reduction of endothelial cell proliferation and migration in a porcine aortic endothelial (PAE) cell model. Cell cycle studies show a G0/G1 arrest in PAE cells harboring LINE-1 de novo retrotransposition events. Remarkably, in in situ analysis LINE-1-encoded ORF2p was not detectable in tumor blood vessels of different human organs while vascular endothelial cells of corresponding normal organs strongly expressed LINE-1 ORF2p. Quantitative RT-PCR analysis revealed that LINE-1 de novo retrotransposition influences selectively the expression of some angiogenic factors such as VEGF and Tie-2. Thus, our data suggest that LINE-1 de novo retrotransposition events might suppress angiogenesis and tumor vascularisation by reducing the angiogenic capacity of vascular endothelial cells.
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34
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Han JS. Non-long terminal repeat (non-LTR) retrotransposons: mechanisms, recent developments, and unanswered questions. Mob DNA 2010; 1:15. [PMID: 20462415 PMCID: PMC2881922 DOI: 10.1186/1759-8753-1-15] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 05/12/2010] [Indexed: 12/22/2022] Open
Abstract
Non-long terminal repeat (non-LTR) retrotransposons are present in most eukaryotic genomes. In some species, such as humans, these elements are the most abundant genome sequence and continue to replicate to this day, creating a source of endogenous mutations and potential genotoxic stress. This review will provide a general outline of the replicative cycle of non-LTR retrotransposons. Recent findings regarding the host regulation of non-LTR retrotransposons will be summarized. Finally, future directions of interest will be discussed.
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Affiliation(s)
- Jeffrey S Han
- Department of Embryology, Carnegie Institution of Washington, Baltimore, MD, USA.
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35
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Belancio VP, Roy-Engel AM, Pochampally RR, Deininger P. Somatic expression of LINE-1 elements in human tissues. Nucleic Acids Res 2010; 38:3909-22. [PMID: 20215437 PMCID: PMC2896524 DOI: 10.1093/nar/gkq132] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
LINE-1 expression damages host DNA via insertions and endonuclease-dependent DNA double-strand breaks (DSBs) that are highly toxic and mutagenic. The predominant tissue of LINE-1 expression has been considered to be the germ line. We show that both full-length and processed L1 transcripts are widespread in human somatic tissues and transformed cells, with significant variation in both L1 expression and L1 mRNA processing. This is the first demonstration that RNA processing is a major regulator of L1 activity. Many tissues also produce translatable spliced transcript (SpORF2). An Alu retrotransposition assay, COMET assays and 53BP1 foci staining show that the SpORF2 product can support functional ORF2 protein expression and can induce DNA damage in normal cells. Tests of the senescence-associated beta-galactosidase expression suggest that expression of exogenous full-length L1, or the SpORF2 mRNA alone in human fibroblasts and adult stem cells triggers a senescence-like phenotype, which is one of the reported responses to DNA damage. In contrast to previous assumptions that L1 expression is germ line specific, the increased spectrum of tissues exposed to L1-associated damage suggests a role for L1 as an endogenous mutagen in somatic tissues. These findings have potential consequences for the whole organism in the form of cancer and mammalian aging.
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Affiliation(s)
- Victoria P Belancio
- Department of Structural and Cellular Biology, Tulane School of Medicine and Tulane Center for Aging, Tulane University, New Orleans, LA 70112, USA
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36
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Unique functions of repetitive transcriptomes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 285:115-88. [PMID: 21035099 DOI: 10.1016/b978-0-12-381047-2.00003-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Repetitive sequences occupy a huge fraction of essentially every eukaryotic genome. Repetitive sequences cover more than 50% of mammalian genomic DNAs, whereas gene exons and protein-coding sequences occupy only ~3% and 1%, respectively. Numerous genomic repeats include genes themselves. They generally encode "selfish" proteins necessary for the proliferation of transposable elements (TEs) in the host genome. The major part of evolutionary "older" TEs accumulated mutations over time and fails to encode functional proteins. However, repeats have important functions also on the RNA level. Repetitive transcripts may serve as multifunctional RNAs by participating in the antisense regulation of gene activity and by competing with the host-encoded transcripts for cellular factors. In addition, genomic repeats include regulatory sequences like promoters, enhancers, splice sites, polyadenylation signals, and insulators, which actively reshape cellular transcriptomes. TE expression is tightly controlled by the host cells, and some mechanisms of this regulation were recently decoded. Finally, capacity of TEs to proliferate in the host genome led to the development of multiple biotechnological applications.
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37
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Wang Y, Liska F, Gosele C, Sedová L, Kren V, Krenová D, Ivics Z, Hubner N, Izsvák Z. A novel active endogenous retrovirus family contributes to genome variability in rat inbred strains. Genome Res 2009; 20:19-27. [PMID: 19887576 DOI: 10.1101/gr.100073.109] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Endogenous retroviruses (ERVs) contribute to a range of germline, as well as somatic mutations in mammals. However, autonomous retrotransposition of potentially active elements has not been demonstrated in the rat genome. We cloned an insertion that disrupted the normal splicing of the Cntrob gene that was subsequently identified as a nonautonomous, novel endogenous retrovirus of the RnERV-K8e family. The RnERV-K8e family is closely related to the recently reported MmERV-K10c elements, but differs from the autonomous mouse MusD or IAP families. In addition, we identified a novel, unexpectedly close relative of RnERV-K8e in the mouse, suggesting ERV-K cross-species transmission between mice and rats. We cloned a potentially autonomous RnERV-K8e element identified by in silico analysis and, using an in vitro retrotransposition assay, demonstrated that it is capable of retrotransposition. This particular element (named Rat-rho, pronounced "retro") encodes a retroviral envelope gene (env); however, env is not required for de novo retrotransposition events. Significant levels of RnERV-K8e-associated genetic polymorphisms were detected among inbred rat strains, suggesting ongoing retrotransposition in the rat genome. This study identifies an ERV-K-type family in rats that shows obvious signs of recent activity. Ongoing retrotranspositional activity may significantly add to genomic variability among inbred rat strains.
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Affiliation(s)
- Yongming Wang
- Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
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38
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Schneider AM, Duffield AS, Symer DE, Burns KH. Roles of retrotransposons in benign and malignant hematologic disease. CELLSCIENCE 2009; 6:121-145. [PMID: 20200603 PMCID: PMC2830787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Nearly half of our genomes are repetitive sequences derived from retrotransposons. These repeats have accumulated by a 'copy-and-paste' mechanism whereby: (i.) a genomic template sequence is transcribed to RNA, (ii.) the RNA is reverse-transcribed, and (iii.) the DNA copy is inserted at a new location in the host genome. As we remain susceptible to new retrotransposition events, many of these insertions are highly polymorphic. Transposons are of interest since insertions into both coding and non-coding gene regions have been associated with a wide variety of functional sequelae and because transposable elements can be involved in genomic rearrangements in transformed cells. In this review, we highlight how expression of retrotransposons, de novo and polymorphic transposon insertions, and genomic rearrangements that these repeats potentiate contribute to both benign and neoplastic hematopoietic diseases.
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Affiliation(s)
- Anna M Schneider
- Dept. of Molecular Biology & Genetics, Johns Hopkins University School of Medicine
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39
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An W, Davis ES, Thompson TL, O'Donnell KA, Lee CY, Boeke JD. Plug and play modular strategies for synthetic retrotransposons. Methods 2009; 49:227-35. [PMID: 19481606 DOI: 10.1016/j.ymeth.2009.05.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 05/08/2009] [Accepted: 05/22/2009] [Indexed: 01/17/2023] Open
Abstract
Recent progress in L1 biology highlights its role as a major driving force in the evolution of mammalian genome structure and function. This coincides with direct confirmation of the preponderance of long interspersed elements in mammalian genomes at the nucleotide level by large scale sequencing efforts. Two assay systems have been prominently featured in L1 studies over the past decade, which are used to assess L1 activities in cultured cells and transgenic mice respectively. However, constructing retrotransposon assay vectors and subsequent mapping of integration sites remain technically challenging aspects of the field. Synthetic biology approaches have changed the playing field with regard to the strategic design of retrotransposons. To streamline the construction and optimization of synthetic retrotransposons, we have implemented a highly efficient modular design for L1 vectors allowing "plug and play" swapping of individual modules as new knowledge is gained and optimization of constructs proceeds. Seven functional modules are divided by strategically placed unique restriction sites. These are utilized to facilitate module exchange and construction of L1 vectors for gene targeting, transgenesis and cell culture assays. A "double SfiI" strategy utilizing two non-complementary overhangs allows insert swapping to be carried out with a single, robust restriction/ligation cycle. The double-SfiI strategy is generic and can be applied to many other problems in synthetic biology or genetic engineering. To facilitate genomic mapping of L1 insertions, we have developed an optimized inverse PCR protocol using 4-base cutters and step-down cycling conditions. Using this protocol, de novo L1 insertions can be efficiently recovered after a single round of PCR. The proposed modular design also incorporates features allowing streamlined insertion mapping without repeated optimization. Furthermore, we have presented evidence that efficient L1 retrotransposition is not dependent on pCEP4 conferred autonomous replication capabilities when a shortened puromycin selection protocol is used, providing a great opportunity for further optimization of L1 cell culture assay vectors by using alternative vector backbones.
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Affiliation(s)
- Wenfeng An
- School of Molecular Biosciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA.
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40
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The L1 retrotransposition assay: a retrospective and toolkit. Methods 2009; 49:219-26. [PMID: 19398011 DOI: 10.1016/j.ymeth.2009.04.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 03/18/2009] [Accepted: 04/10/2009] [Indexed: 11/23/2022] Open
Abstract
LINE1s (L1s) are a class of mammalian non-LTR (long terminal repeat) retroelements that make up nearly 20% of the human genome. Because of the difficulty of studying the mobilization of endogenous L1s, an exogenous cell culture retrotransposition assay has become integral to research in L1 biology. This assay has allowed for investigation of the mechanism and consequences of mobilization of this retroelement, both in cell lines and in whole animal models. In this paper, we outline the genesis of in vitro retrotransposition systems which led to the development of the L1 retrotransposition assay in the mid-1990s. We then provide a retrospective, describing the many uses and variations of this assay, ending with caveats and predictions for future developments. Finally, we provide detailed protocols on the application of the retrotransposition assay, including lists of constructs available in the L1 research community and cell lines in which this assay has been applied.
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41
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Non-LTR retrotransposons encode noncanonical RRM domains in their first open reading frame. Proc Natl Acad Sci U S A 2009; 106:731-6. [PMID: 19139409 DOI: 10.1073/pnas.0809964106] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Non-LTR retrotransposons (NLRs) are a unique class of mobile genetic elements that have significant impact on the evolution of eukaryotic genomes. However, the molecular details and functions of their encoded proteins, in particular of the accessory ORF1p proteins, are poorly understood. Here, we identify noncanonical RNA-recognition-motifs (RRMs) in several phylogenetically unrelated NLR ORF1p proteins. This provides an explanation for their RNA-binding properties and clearly shows that they are not related to the retroviral nucleocapsid protein Gag, despite the frequent presence of CCHC zinc knuckles. In particular, we characterize the ORF1p protein of the human long interspersed nuclear element 1 (LINE-1 or L1). We show that L1ORF1p is a multidomain protein, consisting of a coiled coil (cc), RRM, and C-terminal domain (CTD). Most importantly, we solved the crystal structure of the RRM domain, which is characterized by extended loops stabilized by unique salt bridges. Furthermore, we demonstrate that L1ORF1p trimerizes via its N-terminal cc domain, and we suggest that this property is functionally important for all homologues. The formation of distinct complexes with single-stranded nucleic acids requires the presence of the RRM and CTD domains on the same polypeptide chain as well as their close cooperation. Finally, the phylogenetic analysis of mammalian L1ORF1p shows an ancient origin of the RRM domain and supports a modular evolution of NLRs.
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