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Bhat A, Ghatage T, Bhan S, Lahane GP, Dhar A, Kumar R, Pandita RK, Bhat KM, Ramos KS, Pandita TK. Role of Transposable Elements in Genome Stability: Implications for Health and Disease. Int J Mol Sci 2022; 23:7802. [PMID: 35887150 PMCID: PMC9319628 DOI: 10.3390/ijms23147802] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/07/2022] [Accepted: 07/12/2022] [Indexed: 12/11/2022] Open
Abstract
Most living organisms have in their genome a sizable proportion of DNA sequences capable of mobilization; these sequences are commonly referred to as transposons, transposable elements (TEs), or jumping genes. Although long thought to have no biological significance, advances in DNA sequencing and analytical technologies have enabled precise characterization of TEs and confirmed their ubiquitous presence across all forms of life. These findings have ignited intense debates over their biological significance. The available evidence now supports the notion that TEs exert major influence over many biological aspects of organismal life. Transposable elements contribute significantly to the evolution of the genome by giving rise to genetic variations in both active and passive modes. Due to their intrinsic nature of mobility within the genome, TEs primarily cause gene disruption and large-scale genomic alterations including inversions, deletions, and duplications. Besides genomic instability, growing evidence also points to many physiologically important functions of TEs, such as gene regulation through cis-acting control elements and modulation of the transcriptome through epigenetic control. In this review, we discuss the latest evidence demonstrating the impact of TEs on genome stability and the underling mechanisms, including those developed to mitigate the deleterious impact of TEs on genomic stability and human health. We have also highlighted the potential therapeutic application of TEs.
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Affiliation(s)
- Audesh Bhat
- Centre for Molecular Biology, Central University of Jammu, Jammu 181143, India;
| | - Trupti Ghatage
- Department of Pharmacy, BITS-Pilani Hyderabad Campus, Hyderabad 500078, India; (T.G.); (G.P.L.); (A.D.)
| | - Sonali Bhan
- Centre for Molecular Biology, Central University of Jammu, Jammu 181143, India;
| | - Ganesh P. Lahane
- Department of Pharmacy, BITS-Pilani Hyderabad Campus, Hyderabad 500078, India; (T.G.); (G.P.L.); (A.D.)
| | - Arti Dhar
- Department of Pharmacy, BITS-Pilani Hyderabad Campus, Hyderabad 500078, India; (T.G.); (G.P.L.); (A.D.)
| | - Rakesh Kumar
- Department of Biotechnology, Shri Mata Vaishnav Devi University, Katra 182320, India;
| | - Raj K. Pandita
- Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA;
| | - Krishna M. Bhat
- Department of Molecular Medicine, University of South Florida, Tampa, FL 33612, USA;
| | - Kenneth S. Ramos
- Center for Genomics and Precision Medicine, Texas A&M College of Medicine, Houston, TX 77030, USA;
| | - Tej K. Pandita
- Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA;
- Center for Genomics and Precision Medicine, Texas A&M College of Medicine, Houston, TX 77030, USA;
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Pinter TB, Ervin CS, Deb A, Penner-Hahn JE, Pecoraro VL. Cu(I) Binding to Designed Proteins Reveals a Putative Copper Binding Site of the Human Line1 Retrotransposon Protein ORF1p. Inorg Chem 2022; 61:5084-5091. [PMID: 35286080 PMCID: PMC10754372 DOI: 10.1021/acs.inorgchem.2c00057] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Long interspersed nuclear elements-1 (L1) are autonomous retrotransposons that encode two proteins in different open reading frames (ORF1 and ORF2). The ORF1p, which may be an RNA binding and chaperone protein, contains a three-stranded coiled coil (3SCC) domain that facilitates the formation of the biologically active homotrimer. This 3SCC domain is composed of seven amino acid (heptad) repeats as found in native and designed peptides and a stammer that modifies the helical structure. Cysteine residues occur at three hydrophobic positions (2 a and 1 d sites) within this domain. We recently showed that the cysteine layers in ORF1p and model de novo designed peptides bind the toxic metalloid lead(II) with high affinities, a feature that had not been previously recognized. However, there is little understanding of how essential metal ions might interact with this metal binding domain. We have, therefore, investigated the copper(I) binding properties of analogous de novo designed 3SCCs that contain cysteine layers within the hydrophobic core. The results from UV-visible and X-ray absorption spectroscopy show that these designed peptides bind Cu(I) with high affinity in a pH-dependent manner. At pH 9, monomeric trigonal planar Cu(I)S3 centers are formed with 1 equiv of metal, while dinuclear centers form with a second equivalent of metal. At physiologic pH conditions, the dinuclear center forms cooperatively. These data suggest that ORF1p is capable of binding two copper ions to its tris(cysteine) layers. This has major implications for ORF1p coiled coil domain stability and dynamics, ultimately potentially impacting the resulting biological activity.
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Affiliation(s)
- Tyler B.J. Pinter
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- These authors contributed equally to this work
| | - Catherine S. Ervin
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- These authors contributed equally to this work
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - James E. Penner-Hahn
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Pappalardo AM, Ferrito V, Biscotti MA, Canapa A, Capriglione T. Transposable Elements and Stress in Vertebrates: An Overview. Int J Mol Sci 2021; 22:1970. [PMID: 33671215 PMCID: PMC7922186 DOI: 10.3390/ijms22041970] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/13/2021] [Accepted: 02/14/2021] [Indexed: 12/17/2022] Open
Abstract
Since their identification as genomic regulatory elements, Transposable Elements (TEs) were considered, at first, molecular parasites and later as an important source of genetic diversity and regulatory innovations. In vertebrates in particular, TEs have been recognized as playing an important role in major evolutionary transitions and biodiversity. Moreover, in the last decade, a significant number of papers has been published highlighting a correlation between TE activity and exposition to environmental stresses and dietary factors. In this review we present an overview of the impact of TEs in vertebrate genomes, report the silencing mechanisms adopted by host genomes to regulate TE activity, and finally we explore the effects of environmental and dietary factor exposures on TE activity in mammals, which is the most studied group among vertebrates. The studies here reported evidence that several factors can induce changes in the epigenetic status of TEs and silencing mechanisms leading to their activation with consequent effects on the host genome. The study of TE can represent a future challenge for research for developing effective markers able to detect precocious epigenetic changes and prevent human diseases.
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Affiliation(s)
- Anna Maria Pappalardo
- Department of Biological, Geological and Environmental Sciences-Section of Animal Biology "M. La Greca", University of Catania, Via Androne 81, 95124 Catania, Italy
| | - Venera Ferrito
- Department of Biological, Geological and Environmental Sciences-Section of Animal Biology "M. La Greca", University of Catania, Via Androne 81, 95124 Catania, Italy
| | - Maria Assunta Biscotti
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Adriana Canapa
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Teresa Capriglione
- Department of Biology, University of Naples "Federico II", Via Cinthia 21-Ed7, 80126 Naples, Italy
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Del Re B, Giorgi G. Long INterspersed element-1 mobility as a sensor of environmental stresses. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:465-493. [PMID: 32144842 DOI: 10.1002/em.22366] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 03/03/2020] [Accepted: 03/04/2020] [Indexed: 06/10/2023]
Abstract
Long INterspersed element (LINE-1, L1) retrotransposons are the most abundant transposable elements in the human genome, constituting approximately 17%. They move by a "copy-paste" mechanism, involving reverse transcription of an RNA intermediate and insertion of its cDNA copy at a new site in the genome. L1 retrotransposition (L1-RTP) can cause insertional mutations, alter gene expression, transduce exons, and induce epigenetic dysregulation. L1-RTP is generally repressed; however, a number of observations collected over about 15 years revealed that it can occur in response to environmental stresses. Moreover, emerging evidence indicates that L1-RTP can play a role in the onset of several neurological and oncological diseases in humans. In recent years, great attention has been paid to the exposome paradigm, which proposes that health effects of an environmental factor should be evaluated considering both cumulative environmental exposures and the endogenous processes resulting from the biological response. L1-RTP could be an endogenous process considered for this application. Here, we summarize the current understanding of environmental factors that can affect the retrotransposition of human L1 elements. Evidence indicates that L1-RTP alteration is triggered by numerous and various environmental stressors, such as chemical agents (heavy metals, carcinogens, oxidants, and drugs), physical agents (ionizing and non-ionizing radiations), and experiential factors (voluntary exercise, social isolation, maternal care, and environmental light/dark cycles). These data come from in vitro studies on cell lines and in vivo studies on transgenic animals: future investigations should be focused on physiologically relevant models to gain a better understanding of this topic.
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Affiliation(s)
- Brunella Del Re
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, Bologna, Italy
| | - Gianfranco Giorgi
- Department of Biological, Geological and Environmental Sciences, Alma Mater Studiorum University of Bologna, Bologna, Italy
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Abstract
Transposable elements (TEs) are low-complexity elements (e.g., LINEs, SINEs, SVAs, and HERVs) that make up to two-thirds of the human genome. There is mounting evidence that TEs play an essential role in molecular functions that influence genomic plasticity and gene expression regulation. With the advent of next-generation sequencing approaches, our understanding of the relationship between TEs and psychiatric disorders will greatly improve. In this chapter, the Authors comprehensively summarize the state-of the-art of TE research in animal models and humans supporting a framework in which TEs play a functional role in mechanisms affecting a variety of behaviors, including neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Finally, the Authors discuss recent therapeutic applications raised from the increasing experimental evidence on TE functional mechanisms.
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Affiliation(s)
- G Guffanti
- McLean Hospital - Harvard Medical School, Belmont, MA, USA.
| | - A Bartlett
- Department of Psychology, University of Massachusetts, Boston, Boston, MA, USA
| | - P DeCrescenzo
- McLean Hospital - Harvard Medical School, Belmont, MA, USA
| | - F Macciardi
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - R Hunter
- Department of Psychology, University of Massachusetts, Boston, Boston, MA, USA
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Alexandrov PN, Pogue AI, Lukiw WJ. Synergism in aluminum and mercury neurotoxicity. INTEGRATIVE FOOD, NUTRITION AND METABOLISM 2018; 5:10.15761/IFNM.1000214. [PMID: 29938114 PMCID: PMC6013271 DOI: 10.15761/ifnm.1000214] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Aluminum and mercury are common neurotoxic contaminants in our environment - from the air we breathe to the water that we drink to the foods that we eat. It is remarkable that to date neither of these two well-established environmental neurotoxins (i.e. those having a general toxicity towards brain cells) and genotoxins (those agents which exhibit directed toxicity toward the genetic apparatus) have been critically studied, nor have their neurotoxicities been evaluated in human neurobiology or in cells of the human central nervous system (CNS). In this paper we report the effects of added aluminum [sulfate; Al₂(SO₄)₃] and/or mercury [sulfate; HgSO4] to human neuronal-glial (HNG) cells in primary co-culture using the evolution of the pro-inflammatory transcription factor NF-kB (p50/p65) complex as a critical indicator for the onset of inflammatory neurodegeneration and pathogenic inflammatory signaling. As indexed by significant induction of the NF-kB (p50/p65) complex the results indicate: (i) a notable increase in pro-inflammatory signaling imparted by each of these two environmental neurotoxins toward HNG cells in the ambient 20-200 nM range; and (ii) a significant synergism in the neurotoxicity when aluminum (sulfate) and mercury (sulfate) were added together. This is the first report on the neurotoxic effects of aluminum sulfate and/or mercury sulfate on the initiation of inflammatory signaling in human brain cells in primary culture. The effects aluminum+mercury together on other neurologically important signaling molecules or the effects of other combinations of common environmental metallic neurotoxins to human neurobiology currently remain not well understood but certainly warrant additional investigation and further study in laboratory animals, in human primary tissue cultures of CNS cells, and in other neurobiologically realistic experimental test systems.
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Affiliation(s)
| | | | - Walter J Lukiw
- Russian Academy of Medical Sciences, Moscow 113152, Russia
- Alchem Biotek Research, Toronto ON M5S 1A8, Canada
- LSU Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112, USA
- Department of Neurology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112, USA
- Department of Ophthalmology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite 904, New Orleans LA 70112, USA
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Cook PR, Tabor GT. Deciphering fact from artifact when using reporter assays to investigate the roles of host factors on L1 retrotransposition. Mob DNA 2016; 7:23. [PMID: 27895722 PMCID: PMC5120415 DOI: 10.1186/s13100-016-0079-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 11/04/2016] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND The Long INterspersed Element-1 (L1, LINE-1) is the only autonomous mobile DNA element in humans and has generated as much as half of the genome. Due to increasing clinical interest in the roles of L1 in cancer, embryogenesis and neuronal development, it has become a priority to understand L1-host interactions and identify host factors required for its activity. Apropos to this, we recently reported that L1 retrotransposition in HeLa cells requires phosphorylation of the L1 protein ORF1p at motifs targeted by host cell proline-directed protein kinases (PDPKs), which include the family of mitogen-activated protein kinases (MAPKs). Using two engineered L1 reporter assays, we continued our investigation into the roles of MAPKs in L1 activity. RESULTS We found that the MAPK p38δ phosphorylated ORF1p on three of its four PDPK motifs required for L1 activity. In addition, we found that a constitutively active p38δ mutant appeared to promote L1 retrotransposition in HeLa cells. However, despite the consistency of these findings with our earlier work, we identified some technical concerns regarding the experimental methodology. Specifically, we found that exogenous expression of p38δ appeared to affect at least one heterologous promoter in an engineered L1 reporter, as well as generate opposing effects on two different reporters. We also show that two commercially available non-targeting control (NTC) siRNAs elicit drastically different effects on the apparent retrotransposition reported by both L1 assays, which raises concerns about the use of NTCs as normalizing controls. CONCLUSIONS Engineered L1 reporter assays have been invaluable for determining the functions and critical residues of L1 open reading frames, as well as elucidating many aspects of L1 replication. However, our results suggest that caution is required when interpreting data obtained from L1 reporters used in conjunction with exogenous gene expression or siRNA.
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Affiliation(s)
- Pamela R. Cook
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 8 Center Drive, Bethesda, MD 20892 USA
| | - G. Travis Tabor
- National Institute of Child Health and Human Development, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892 USA
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Habibi L, Pedram M, AmirPhirozy A, Bonyadi K. Mobile DNA Elements: The Seeds of Organic Complexity on Earth. DNA Cell Biol 2015. [DOI: 10.1089/dna.2015.2938] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Laleh Habibi
- Department of Pharmaceutics, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
- Cellular and Molecular Nutrition Department, School of Nutritional Science and Dietetics, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehrdad Pedram
- Department of Genetics and Molecular Medicine, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Akbar AmirPhirozy
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Khadijeh Bonyadi
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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Morales ME, Servant G, Ade C, Roy-Enge AM. Altering Genomic Integrity: Heavy Metal Exposure Promotes Transposable Element-Mediated Damage. Biol Trace Elem Res 2015; 166:24-33. [PMID: 25774044 PMCID: PMC4696754 DOI: 10.1007/s12011-015-0298-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 03/03/2015] [Indexed: 12/13/2022]
Abstract
Maintenance of genomic integrity is critical for cellular homeostasis and survival. The active transposable elements (TEs) composed primarily of three mobile element lineages LINE-1, Alu, and SVA comprise approximately 30% of the mass of the human genome. For the past 2 decades, studies have shown that TEs significantly contribute to genetic instability and that TE-caused damages are associated with genetic diseases and cancer. Different environmental exposures, including several heavy metals, influence how TEs interact with its host genome increasing their negative impact. This mini-review provides some basic knowledge on TEs, their contribution to disease, and an overview of the current knowledge on how heavy metals influence TE-mediated damage.
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Affiliation(s)
- Maria E. Morales
- Department of Epidemiology and Tulane Cancer Center, SL-66, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112
| | - Geraldine Servant
- Department of Epidemiology and Tulane Cancer Center, SL-66, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112
| | - Catherine Ade
- Department of Cellular and Molecular Biology, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112
| | - Astrid M. Roy-Enge
- Department of Epidemiology and Tulane Cancer Center, SL-66, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112
- Corresponding author: Astrid M. Roy-Engel, Ph.D., Department of Epidemiology, Tulane Cancer Center, SL66, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112. , Phone: (504) 988-6316, Fax: (504) 988-5516
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Miousse IR, Chalbot MCG, Lumen A, Ferguson A, Kavouras IG, Koturbash I. Response of transposable elements to environmental stressors. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2015; 765:19-39. [PMID: 26281766 PMCID: PMC4544780 DOI: 10.1016/j.mrrev.2015.05.003] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 05/27/2015] [Accepted: 05/28/2015] [Indexed: 12/21/2022]
Abstract
Transposable elements (TEs) comprise a group of repetitive sequences that bring positive, negative, as well as neutral effects to the host organism. Earlier considered as "junk DNA," TEs are now well-accepted driving forces of evolution and critical regulators of the expression of genetic information. Their activity is regulated by epigenetic mechanisms, including methylation of DNA and histone modifications. The loss of epigenetic control over TEs, exhibited as loss of DNA methylation and decondensation of the chromatin structure, may result in TEs reactivation, initiation of their insertional mutagenesis (retrotransposition) and has been reported in numerous human diseases, including cancer. Accumulating evidence suggests that these alterations are not the simple consequences of the disease, but often may drive the pathogenesis, as they can be detected early during disease development. Knowledge derived from the in vitro, in vivo, and epidemiological studies, clearly demonstrates that exposure to ubiquitous environmental stressors, many of which are carcinogens or suspected carcinogens, are capable of causing alterations in methylation and expression of TEs and initiate retrotransposition events. Evidence summarized in this review suggests that TEs are the sensitive endpoints for detection of effects caused by such environmental stressors, as ionizing radiation (terrestrial, space, and UV-radiation), air pollution (including particulate matter [PM]-derived and gaseous), persistent organic pollutants, and metals. Furthermore, the significance of these effects is characterized by their early appearance, persistence and presence in both, target organs and peripheral blood. Altogether, these findings suggest that TEs may potentially be introduced into safety and risk assessment and serve as biomarkers of exposure to environmental stressors. Furthermore, TEs also show significant potential to become invaluable surrogate biomarkers in clinic and possible targets for therapeutic modalities for disease treatment and prevention.
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Affiliation(s)
- Isabelle R Miousse
- Department of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
| | - Marie-Cecile G Chalbot
- Department of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
| | - Annie Lumen
- Division of Biochemical Toxicology, National Center for Toxicological Research, US Food and Drug Administration, Jefferson, AR 72079, USA.
| | - Alesia Ferguson
- Department of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
| | - Ilias G Kavouras
- Department of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
| | - Igor Koturbash
- Department of Environmental and Occupational Health, Fay W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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Karimi A, Madjd Z, Habibi L, Akrami SM. Exposure of hepatocellular carcinoma cells to low-level As₂O₃ causes an extra toxicity pathway via L1 retrotransposition induction. Toxicol Lett 2014; 229:111-7. [PMID: 24960058 DOI: 10.1016/j.toxlet.2014.05.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 05/29/2014] [Accepted: 05/30/2014] [Indexed: 11/17/2022]
Abstract
Various mechanisms have been proposed for toxicity and carcinogenesis pattern of arsenic, a naturally occurring metalloid. The extent to which the long interspersed element-1 (LINE-1) retrotransposon, an ubiquitous retroelement with autonomous mobility, can be influenced upon exposure to low-level arsenic remains to be elucidated. The aim of this study was to evaluate the possible effect of low-level As2O3 on L1 retrotransposition alteration in human hepatocellular carcinoma cells (HepG2). L1 retrotransposition in HepG2 cells was performed by the in vitro retrotransposition assay using an EGFP-tagged L1RP. Following determination of non-cytotoxic concentrations of arsenic by a MTT assay, the cells were transfected with pL1RP-EGFP and then exposed to 0.25, 0.50 and 0.75 μM of As2O3. The amount of EGFP and its copy number in retrotransposed cells were evaluated by FACS and qPCR analysis in treated vs. control cells, respectively. Significant increase in retrotransposition frequency was found after 12 days exposure to 0.50 and 0.75 μM of As2O3 by FACS analysis (P<0.05). Obtained results were further confirmed by real time PCR, which showed significant induction of retrotransposition in all mentioned concentrations. Our findings indicate that low-level long-term As2O3 exposure may pave activation of L1 retrotransposon.
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Affiliation(s)
- Abbas Karimi
- Department of Molecular Medicine, Faculty of Advanced Technologies in Medicine (FATiM), Iran University of Medical Sciences, Tehran, Iran; Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Zahra Madjd
- Department of Molecular Medicine, Faculty of Advanced Technologies in Medicine (FATiM), Iran University of Medical Sciences, Tehran, Iran; Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran; Oncopathology Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Laleh Habibi
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed Mohammad Akrami
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
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