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Kohlrausch FB, Wang F, McKerrow W, Grivainis M, Fenyo D, Keefe DL. Mapping of long interspersed element-1 (L1) insertions by TIPseq provides information about sub chromosomal genetic variation in human embryos. J Assist Reprod Genet 2024; 41:2257-2269. [PMID: 38951360 PMCID: PMC11405744 DOI: 10.1007/s10815-024-03176-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 06/12/2024] [Indexed: 07/03/2024] Open
Abstract
PURPOSE Retrotransposons play important roles during early development when they are transiently de-repressed during epigenetic reprogramming. Long interspersed element-1 (L1), the only autonomous retrotransposon in humans, comprises 17% of the human genome. We applied the Single Cell Transposon Insertion Profiling by Sequencing (scTIPseq) to characterize and map L1 insertions in human embryos. METHODS Sixteen cryopreserved, genetically tested, human blastocysts, were accessed from consenting couples undergoing IVF at NYU Langone Fertility Center. Additionally, four trios (father, mother, and embryos) were also evaluated. scTIPseq was applied to map L1 insertions in all samples, using L1 locations reported in the 1000 Genomes as controls. RESULTS Twenty-nine unknown and unique insertions were observed in the sixteen embryos. Most were intergenic; no insertions were located in exons or immediately upstream of genes. The location or number of unknown insertions did not differ between euploid and aneuploid embryos, suggesting they are not merely markers of aneuploidy. Rather, scTIPseq provides novel information about sub-chromosomal structural variation in human embryos. Trio analyses showed a parental origin of all L1 insertions in embryos. CONCLUSION Several studies have measured L1 expression at different stages of development in mice, but this study for the first time reports unknown insertions in human embryos that were inherited from one parent, confirming no de novo L1 insertions occurred in parental germline or during embryogenesis. Since one-third of euploid embryo transfers fail, future studies would be useful for understanding whether these sub-chromosomal genetic variants or de novo L1 insertions affect embryo developmental potential.
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Affiliation(s)
- Fabiana B Kohlrausch
- Departamento de Biologia Geral, Instituto de Biologia, Universidade Federal Fluminense, Niterói, RJ, 24210-201, Brazil.
- Department of Obstetrics and Gynecology, New York University, New York, NY, 10016, USA.
| | - Fang Wang
- Department of Obstetrics and Gynecology, New York University, New York, NY, 10016, USA
| | - Wilson McKerrow
- Institute for Systems Genetics, New York University, New York, NY, 10016, USA
| | - Mark Grivainis
- Institute for Systems Genetics, New York University, New York, NY, 10016, USA
| | - David Fenyo
- Institute for Systems Genetics, New York University, New York, NY, 10016, USA
| | - David L Keefe
- Department of Obstetrics and Gynecology, New York University, New York, NY, 10016, USA
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2
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Müller GA, Müller TD. Transfer of membrane(s) matter(s)-non-genetic inheritance of (metabolic) phenotypes? Front Mol Biosci 2024; 11:1347397. [PMID: 38516184 PMCID: PMC10955475 DOI: 10.3389/fmolb.2024.1347397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 01/26/2024] [Indexed: 03/23/2024] Open
Abstract
Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are anchored at the outer phospholipid layer of eukaryotic plasma membranes exclusively by a glycolipid. GPI-APs are not only released into extracellular compartments by lipolytic cleavage. In addition, certain GPI-APs with the glycosylphosphatidylinositol anchor including their fatty acids remaining coupled to the carboxy-terminus of their protein components are also detectable in body fluids, in response to certain stimuli, such as oxidative stress, radicals or high-fat diet. As a consequence, the fatty acid moieties of GPI-APs must be shielded from access of the aqueous environment by incorporation into membranes of extracellular vesicles or into micelle-like complexes together with (lyso)phospholipids and cholesterol. The GPI-APs released from somatic cells and tissues are transferred via those complexes or EVs to somatic as well as pluripotent stem cells with metabolic consequences, such as upregulation of glycogen and lipid synthesis. From these and additional findings, the following hypotheses are developed: i) Transfer of GPI-APs via EVs or micelle-like complexes leads to the induction of new phenotypes in the daughter cells or zygotes, which are presumably not restricted to metabolism. ii) The membrane topographies transferred by the concerted action of GPI-APs and interacting components are replicated by self-organization and self-templation and remain accessible to structural changes by environmental factors. iii) Transfer from mother cells and gametes to their daughter cells and zygotes, respectively, is not restricted to DNA and genes, but also encompasses non-genetic matter, such as GPI-APs and specific membrane constituents. iv) The intergenerational transfer of membrane matter between mammalian organisms is understood as an epigenetic mechanism for phenotypic plasticity, which does not rely on modifications of DNA and histones, but is regarded as molecular mechanism for the inheritance of acquired traits, such as complex metabolic diseases. v) The missing interest in research of non-genetic matter of inheritance, which may be interpreted in the sense of Darwin's "Gemmules" or Galton's "Stirps", should be addressed in future investigations of the philosophy of science and sociology of media.
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Affiliation(s)
- Günter A. Müller
- Institute for Diabetes and Obesity (IDO), Helmholtz Diabetes Center (HDC) at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Oberschleissheim, Germany
- German Center for Diabetes Research (DZD), Oberschleissheim, Germany
- Department of Media Studies, Media, Culture and Society, Faculty of Arts and Humanities, University Paderborn, Paderborn, Germany
| | - Timo D. Müller
- Institute for Diabetes and Obesity (IDO), Helmholtz Diabetes Center (HDC) at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Oberschleissheim, Germany
- German Center for Diabetes Research (DZD), Oberschleissheim, Germany
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Li J, Yuan P, Ma G, Liu Y, Zhang Q, Wang W, Guo Y. The composition dynamics of transposable elements in human blastocysts. J Hum Genet 2023; 68:681-688. [PMID: 37308564 DOI: 10.1038/s10038-023-01169-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 05/11/2023] [Accepted: 06/03/2023] [Indexed: 06/14/2023]
Abstract
Transposable elements (TEs) are mobile DNA sequences that can replicate themselves and play significant roles in embryo development and chromosomal structure remodeling. In this study, we investigated the variation of TEs in blastocysts with different parental genetic backgrounds. We analyzed the proportions of 1137 TEs subfamilies from six classes at the DNA level using Bowtie2 and PopoolationTE2 in 196 blastocysts with abnormal parental chromosomal diseases. Our findings revealed that the parental karyotype was the dominant factor influencing TEs frequencies. Out of the 1116 subfamilies, different frequencies were observed in blastocysts with varying parental karyotypes. The development stage of blastocysts was the second most crucial factor influencing TEs proportions. A total of 614 subfamilies exhibited different proportions at distinct blastocyst stages. Notably, subfamily members belonging to the Alu family showed a high proportion at stage 6, while those from the LINE class exhibited a high proportion at stage 3 and a low proportion at stage 6. Moreover, the proportions of some TEs subfamilies also varied depending on blastocyst karyotype, inner cell mass status, and outer trophectoderm status. We found that 48 subfamilies displayed different proportions between balanced and unbalanced blastocysts. Additionally, 19 subfamilies demonstrated varying proportions among different inner cell mass scores, and 43 subfamilies exhibited different proportions among outer trophectoderm scores. This study suggests that the composition of TEs subfamilies may be influenced by various factors and undergoes dynamic modulation during embryo development.
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Affiliation(s)
- Jian Li
- Department of Clinical Laboratory, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Ping Yuan
- IVF Center, Department of Obstetrics and Gynecology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- IVF Center, The First People's Hospital of Kashi Prefecture, Kashi, China
| | - Guangwei Ma
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, China
| | - Ying Liu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Reproductive Medical Center, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Qingxue Zhang
- IVF Center, Department of Obstetrics and Gynecology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Wenjun Wang
- IVF Center, Department of Obstetrics and Gynecology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
| | - Yabin Guo
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
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4
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Grigorash BB, van Essen D, Liang G, Grosse L, Emelyanov A, Kang Z, Korablev A, Kanzler B, Molina C, Lopez E, Demidov ON, Garrido C, Liu F, Saccani S, Bulavin DV. p16 High senescence restricts cellular plasticity during somatic cell reprogramming. Nat Cell Biol 2023; 25:1265-1278. [PMID: 37652981 DOI: 10.1038/s41556-023-01214-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 07/24/2023] [Indexed: 09/02/2023]
Abstract
Despite advances in four-factor (4F)-induced reprogramming (4FR) in vitro and in vivo, how 4FR interconnects with senescence remains largely under investigated. Here, using genetic and chemical approaches to manipulate senescent cells, we show that removal of p16High cells resulted in the 4FR of somatic cells into totipotent-like stem cells. These cells expressed markers of both pluripotency and the two-cell embryonic state, readily formed implantation-competent blastoids and, following morula aggregation, contributed to embryonic and extraembryonic lineages. We identified senescence-dependent regulation of nicotinamide N-methyltransferase as a key mechanism controlling the S-adenosyl-L-methionine levels during 4FR that was required for expression of the two-cell genes and acquisition of an extraembryonic potential. Importantly, a partial 4F epigenetic reprogramming in old mice was able to reverse several markers of liver aging only in conjunction with the depletion of p16High cells. Our results show that the presence of p16High senescent cells limits cell plasticity, whereas their depletion can promote a totipotent-like state and histopathological tissue rejuvenation during 4F reprogramming.
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Affiliation(s)
- Bogdan B Grigorash
- Institute for Research on Cancer and Aging of Nice (IRCAN), Université Côte d'Azur, INSERM, CNRS, Nice, France
- INSERM UMR1231, LipSTIC, University of Burgundy Franche-Comté, Dijon, France
| | - Dominic van Essen
- Institute for Research on Cancer and Aging of Nice (IRCAN), Université Côte d'Azur, INSERM, CNRS, Nice, France
| | - Guixian Liang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Beijing, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
| | - Laurent Grosse
- Institute for Research on Cancer and Aging of Nice (IRCAN), Université Côte d'Azur, INSERM, CNRS, Nice, France
| | - Alexander Emelyanov
- Institute for Research on Cancer and Aging of Nice (IRCAN), Université Côte d'Azur, INSERM, CNRS, Nice, France
| | - Zhixin Kang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Beijing, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
| | - Alexey Korablev
- Institute for Research on Cancer and Aging of Nice (IRCAN), Université Côte d'Azur, INSERM, CNRS, Nice, France
| | - Benoît Kanzler
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Clement Molina
- Institute for Research on Cancer and Aging of Nice (IRCAN), Université Côte d'Azur, INSERM, CNRS, Nice, France
| | - Elsa Lopez
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Oleg N Demidov
- INSERM UMR1231, LipSTIC, University of Burgundy Franche-Comté, Dijon, France
- Institute of Cytology, RAS, St Petersburg, Russia
- Sirius University, Sochi, Russia
| | - Carmen Garrido
- INSERM UMR1231, LipSTIC, University of Burgundy Franche-Comté, Dijon, France
| | - Feng Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Beijing, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
- School of Life Sciences, Shandong University, Qingdao, China
| | - Simona Saccani
- Institute for Research on Cancer and Aging of Nice (IRCAN), Université Côte d'Azur, INSERM, CNRS, Nice, France
| | - Dmitry V Bulavin
- Institute for Research on Cancer and Aging of Nice (IRCAN), Université Côte d'Azur, INSERM, CNRS, Nice, France.
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5
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Berteli TS, Wang F, Navarro PA, Kohlrausch FB, Keefe DL. A pilot study of LINE-1 copy number and telomere length with aging in human sperm. J Assist Reprod Genet 2023; 40:1845-1854. [PMID: 37382785 PMCID: PMC10371944 DOI: 10.1007/s10815-023-02857-1] [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: 03/27/2023] [Accepted: 06/03/2023] [Indexed: 06/30/2023] Open
Abstract
PURPOSE Unlike other cells in the body, in sperm, telomere length (TL) increases with age. TL can regulate nearby genes, and the subtelomeric region is rich in retrotransposons. We hypothesized that age-related telomere lengthening in sperm might suppress Long Interspersed Element 1 (LINE-1/L1), the only competent retrotransposon in humans. METHODS We measured L1 copy number (L1-CN) and sperm telomere length (STL) from young and older men to evaluate the relationship between age, TL and L1-CN. We also evaluated L1-CN and TL in individual sperm to determine whether these variables influence sperm morphology. STL was assayed by Multiplex quantitative polymerase chain reaction method (mmqPCR) and L1-CN by Quantitative polymerase chain reaction (qPCR). RESULTS We found that STL increased, and L1-CN decreased significantly with paternal age. STL in normal single sperm was significantly higher than in abnormal sperm. L1-CN did not differ between normal and abnormal sperm. Furthermore, morphologically normal sperm have longer telomeres than abnormal sperm. CONCLUSIONS Elongation of telomeres in the male germline could repress retrotransposition, which tends to increase with cellular aging. More studies in larger cohorts across a wide age span are needed to confirm our conclusions and explore their biological and clinical significance.
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Affiliation(s)
- Thalita S Berteli
- Department of Obstetrics and Gynecology, Langone Medical Center, New York University, 462, 1st Avenue, New York, NY, 10016, USA.
- Human Reproduction Division, Department of Gynecology and Obstetrics, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil.
| | - Fang Wang
- Department of Obstetrics and Gynecology, Langone Medical Center, New York University, 462, 1st Avenue, New York, NY, 10016, USA
| | - Paula A Navarro
- Human Reproduction Division, Department of Gynecology and Obstetrics, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Fabiana B Kohlrausch
- Department of Obstetrics and Gynecology, Langone Medical Center, New York University, 462, 1st Avenue, New York, NY, 10016, USA
- Human Genetics Laboratory, Fluminense Federal University, Niteroi, RJ, Brazil
| | - David L Keefe
- Department of Obstetrics and Gynecology, Langone Medical Center, New York University, 462, 1st Avenue, New York, NY, 10016, USA
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6
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Lin CW, Ellegood J, Tamada K, Miura I, Konda M, Takeshita K, Atarashi K, Lerch JP, Wakana S, McHugh TJ, Takumi T. An old model with new insights: endogenous retroviruses drive the evolvement toward ASD susceptibility and hijack transcription machinery during development. Mol Psychiatry 2023; 28:1932-1945. [PMID: 36882500 PMCID: PMC10575786 DOI: 10.1038/s41380-023-01999-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 02/08/2023] [Accepted: 02/10/2023] [Indexed: 03/09/2023]
Abstract
The BTBR T+Itpr3tf/J (BTBR/J) strain is one of the most valid models of idiopathic autism, serving as a potent forward genetics tool to dissect the complexity of autism. We found that a sister strain with an intact corpus callosum, BTBR TF/ArtRbrc (BTBR/R), showed more prominent autism core symptoms but moderate ultrasonic communication/normal hippocampus-dependent memory, which may mimic autism in the high functioning spectrum. Intriguingly, disturbed epigenetic silencing mechanism leads to hyperactive endogenous retrovirus (ERV), a mobile genetic element of ancient retroviral infection, which increases de novo copy number variation (CNV) formation in the two BTBR strains. This feature makes the BTBR strain a still evolving multiple-loci model toward higher ASD susceptibility. Furthermore, active ERV, analogous to virus infection, evades the integrated stress response (ISR) of host defense and hijacks the transcriptional machinery during embryonic development in the BTBR strains. These results suggest dual roles of ERV in the pathogenesis of ASD, driving host genome evolution at a long-term scale and managing cellular pathways in response to viral infection, which has immediate effects on embryonic development. The wild-type Draxin expression in BTBR/R also makes this substrain a more precise model to investigate the core etiology of autism without the interference of impaired forebrain bundles as in BTBR/J.
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Affiliation(s)
- Chia-Wen Lin
- Laboratory for Mental Biology, RIKEN Brain Science Institute, Wako, 351-0198, Saitama, Japan
- Laboratory for Circuit and Behavioral Physiology, RIKEN Center for Brain Science, Wako, 351-0198, Saitama, Japan
- Department of Physiology and Cell Biology, Kobe University School of Medicine, Chuo, 650-0017, Kobe, Japan
| | - Jacob Ellegood
- Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, M5T 3H7, Canada
| | - Kota Tamada
- Laboratory for Mental Biology, RIKEN Brain Science Institute, Wako, 351-0198, Saitama, Japan
- Department of Physiology and Cell Biology, Kobe University School of Medicine, Chuo, 650-0017, Kobe, Japan
| | - Ikuo Miura
- Technology and Development Team for Mouse Phenotype Analysis, Japan Mouse Clinic, RIKEN BioResource Research Center, Tsukuba, Ibaraki, 305-0074, Japan
| | - Mikiko Konda
- Department of Microbiology and Immunology, Keio University School of Medicine, Shinjuku, 160-8582, Tokyo, Japan
| | - Kozue Takeshita
- Department of Microbiology and Immunology, Keio University School of Medicine, Shinjuku, 160-8582, Tokyo, Japan
| | - Koji Atarashi
- Department of Microbiology and Immunology, Keio University School of Medicine, Shinjuku, 160-8582, Tokyo, Japan
- RIKEN Center for Integrative Medical Sciences, Tsurumi, 230-0045, Yokohama, Japan
| | - Jason P Lerch
- Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, M5T 3H7, Canada
- Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, Oxfordshire, OX39DU, UK
| | - Shigeharu Wakana
- Technology and Development Team for Mouse Phenotype Analysis, Japan Mouse Clinic, RIKEN BioResource Research Center, Tsukuba, Ibaraki, 305-0074, Japan
| | - Thomas J McHugh
- Laboratory for Circuit and Behavioral Physiology, RIKEN Center for Brain Science, Wako, 351-0198, Saitama, Japan
| | - Toru Takumi
- Laboratory for Mental Biology, RIKEN Brain Science Institute, Wako, 351-0198, Saitama, Japan.
- Department of Physiology and Cell Biology, Kobe University School of Medicine, Chuo, 650-0017, Kobe, Japan.
- RIKEN Center for Biosystems Dynamics Research, Chuo, 650-0047, Kobe, Japan.
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7
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Spadafora C. The epigenetic basis of evolution. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 178:57-69. [PMID: 36720315 DOI: 10.1016/j.pbiomolbio.2023.01.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/17/2022] [Accepted: 01/26/2023] [Indexed: 01/31/2023]
Abstract
An increasing body of data are revealing key roles of epigenetics in evolutionary processes. The scope of this manuscript is to assemble in a coherent frame experimental evidence supporting a role of epigenetic factors and networks, active during embryogenesis, in orchestrating variation-inducing phenomena underlying evolution, seen as a global process. This process unfolds over two crucial levels: i) a flow of RNA-based information - predominantly small regulatory RNAs released from somatic cells exposed to environmental stimuli - taken up by spermatozoa and delivered to oocytes at fertilization and ii) the highly permissive and variation-prone environments offered by zygotes and totipotent early embryos. Totipotent embryos provide a variety of biological tools favouring the emergence of evolutionarily significant phenotypic novelties driven by RNA information. Under this light, neither random genomic mutations, nor the sieving role of natural selection are required, as the sperm-delivered RNA cargo conveys specific information and acts as "phenotypic-inducer" of defined environmentally acquired traits.
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Affiliation(s)
- Corrado Spadafora
- Institute of Translational Pharmacology, National Research Council (CNR), Rome, Italy.
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8
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Bhadsavle SS, Golding MC. Paternal epigenetic influences on placental health and their impacts on offspring development and disease. Front Genet 2022; 13:1068408. [PMID: 36468017 PMCID: PMC9716072 DOI: 10.3389/fgene.2022.1068408] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 11/04/2022] [Indexed: 07/25/2023] Open
Abstract
Our efforts to understand the developmental origins of birth defects and disease have primarily focused on maternal exposures and intrauterine stressors. Recently, research into non-genomic mechanisms of inheritance has led to the recognition that epigenetic factors carried in sperm also significantly impact the health of future generations. However, although researchers have described a range of potential epigenetic signals transmitted through sperm, we have yet to obtain a mechanistic understanding of how these paternally-inherited factors influence offspring development and modify life-long health. In this endeavor, the emerging influence of the paternal epigenetic program on placental development, patterning, and function may help explain how a diverse range of male exposures induce comparable intergenerational effects on offspring health. During pregnancy, the placenta serves as the dynamic interface between mother and fetus, regulating nutrient, oxygen, and waste exchange and coordinating fetal growth and maturation. Studies examining intrauterine maternal stressors routinely describe alterations in placental growth, histological organization, and glycogen content, which correlate with well-described influences on infant health and adult onset of disease. Significantly, the emergence of similar phenotypes in models examining preconception male exposures indicates that paternal stressors transmit an epigenetic memory to their offspring that also negatively impacts placental function. Like maternal models, paternally programmed placental dysfunction exerts life-long consequences on offspring health, particularly metabolic function. Here, focusing primarily on rodent models, we review the literature and discuss the influences of preconception male health and exposure history on placental growth and patterning. We emphasize the emergence of common placental phenotypes shared between models examining preconception male and intrauterine stressors but note that the direction of change frequently differs between maternal and paternal exposures. We posit that alterations in placental growth, histological organization, and glycogen content broadly serve as reliable markers of altered paternal developmental programming, predicting the emergence of structural and metabolic defects in the offspring. Finally, we suggest the existence of an unrecognized developmental axis between the male germline and the extraembryonic lineages that may have evolved to enhance fetal adaptation.
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Affiliation(s)
| | - Michael C. Golding
- Department of Veterinary Physiology and Pharmacology, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
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9
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A hypothesis: Retrotransposons as a relay of epigenetic marks in intergenerational epigenetic inheritance. Gene 2022; 817:146229. [PMID: 35063571 DOI: 10.1016/j.gene.2022.146229] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/13/2021] [Accepted: 01/13/2022] [Indexed: 12/19/2022]
Abstract
Epigenetic marks in gametes, which both respond to the parental environmental factors and shape offspring phenotypes, are usually positioned to mediate intergenerational or transgenerational epigenetic inheritance. Nonetheless, the mechanisms through which gametic epigenetic signatures encode parental acquired phenotypes, and further initiate a cascade of molecular events to affect offspring phenotypes during early embryonic development, remain unclear. Retrotransposons are mobile DNA elements that could resist to genomic epigenetic reprogramming at specific loci and rewire the core regulatory networks of embryogenesis. Increasing evidences show that retrotransposons in the embryonic genome could interact with gametic epigenetic marks, which provides a tentative possibility that retrotransposons may serve as a relay of gametic epigenetic marks to transmit parental acquired traits. Here, we summarize the recent progress in exploring the crosstalk between gametic epigenetic marks and retrotransposons, and the regulation of gene expression and early embryonic development by retrotransposons. Accordingly, deciphering the mystery of interactions between gametic epigenetic marks and retrotransposons during early embryonic development will provide valuable insights into the intergenerational or transgenerational transmission of acquired traits.
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10
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Optimal Treatment of 6-Dimethylaminopurine Enhances the In Vivo Development of Canine Embryos by Rapid Initiation of DNA Synthesis. Int J Mol Sci 2021; 22:ijms22147757. [PMID: 34299380 PMCID: PMC8303139 DOI: 10.3390/ijms22147757] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/16/2021] [Accepted: 07/17/2021] [Indexed: 02/06/2023] Open
Abstract
Artificial activation of oocytes is an important step for successful parthenogenesis and somatic cell nuclear transfer (SCNT). Here, we investigated the initiation of DNA synthesis and in vivo development of canine PA embryos and cloned embryos produced by treatment with 1.9 mM 6-dimethylaminopurine (6-DMAP) for different lengths of time. For experiments, oocytes for parthenogenesis and SCNT oocytes were cultured for 4 min in 10 μM calcium ionophore, and then divided into 2 groups: (1) culture for 2 h in 6-DMAP (DMAP-2h group); (2) culture for 4 h in DMAP (DMAP-4h group). DNA synthesis was clearly detected in all parthenogenetic (PA) embryos and cloned embryos incorporated BrdU 4 h after activation in DMAP-2h and DMAP-4h groups. In vivo development of canine parthenogenetic fetuses was observed after embryo transfer and the implantation rates of PA embryos in DMAP-2h were 34%, which was significantly higher than those in DMAP-4h (6.5%, p < 0.05). However, in SCNT, there was no significant difference in pregnancy rate (DMAP-2h: 41.6% vs. DMAP-4h: 33.3%) and implantation rates (DMAP-2h: 4.94% vs. DMAP-4h: 3.19%) between DMAP-2h and DMAP-4h. In conclusion, the use of DMAP-2h for canine oocyte activation may be ideal for the in vivo development of PA zygotes, but it was not more effective in in vivo development of canine reconstructed SCNT oocytes. The present study demonstrated that DMAP-2h treatment on activation of canine parthenogenesis and SCNT could effectively induce the onset of DNA synthesis during the first cell cycle.
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11
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Mastora E, Christodoulaki A, Papageorgiou K, Zikopoulos A, Georgiou I. Expression of Retroelements in Mammalian Gametes and Embryos. In Vivo 2021; 35:1921-1927. [PMID: 34182464 DOI: 10.21873/invivo.12458] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/18/2021] [Accepted: 05/24/2021] [Indexed: 11/10/2022]
Abstract
Retroelements are genetic mobile elements, expressed during male and female gamete differentiation. Retrotransposons are normally regulated by the methylation machinery, chromatin modifications, non-coding RNAs, and transcription factors, while retrotransposition control is of vital importance in cellular proliferation and differentiation process. Retrotransposition requires a transcription step, by a cellular RNA polymerase, followed by reverse transcription of an RNA intermediate to cDNA and its integration into a new genomic locus. Long interspersed elements (LINEs), human endogenous retroviruses (HERVs), short interspersed elements (SINEs) and SINE-VNTR-Alu elements (SVAs) constitute about half of the human genome, play a crucial role in genome organization, structure and function and interfere with several biological procedures. In this mini review, we discuss recent data regarding retroelement expression (LINE-1, HERVK-10, SVA and VL30) and retrotransposition events in mammalian oocytes and spermatozoa, as well as the importance of their impact on human and mouse preimplantation embryo development.
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Affiliation(s)
- Eirini Mastora
- Laboratory of Medical Genetics, School of Medicine, University of Ioannina and Medical Genetics and Assisted Reproduction Unit, Department of Obstetrics and Gynecology, University Hospital of Ioannina, Ioannina, Greece
| | - Antonia Christodoulaki
- Laboratory of Medical Genetics, School of Medicine, University of Ioannina and Medical Genetics and Assisted Reproduction Unit, Department of Obstetrics and Gynecology, University Hospital of Ioannina, Ioannina, Greece
| | - Kyriaki Papageorgiou
- Department of Biological Applications & Technologies, University of Ioannina and Institute of Molecular Biology and Biotechnology, Division of Biomedical Research, Foundation for Research and Technology, Ioannina, Greece
| | - Athanasios Zikopoulos
- Laboratory of Medical Genetics, School of Medicine, University of Ioannina and Medical Genetics and Assisted Reproduction Unit, Department of Obstetrics and Gynecology, University Hospital of Ioannina, Ioannina, Greece
| | - Ioannis Georgiou
- Laboratory of Medical Genetics, School of Medicine, University of Ioannina and Medical Genetics and Assisted Reproduction Unit, Department of Obstetrics and Gynecology, University Hospital of Ioannina, Ioannina, Greece;
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12
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Fu B, Ma H, Liu D. Functions and Regulation of Endogenous Retrovirus Elements during Zygotic Genome Activation: Implications for Improving Somatic Cell Nuclear Transfer Efficiency. Biomolecules 2021; 11:829. [PMID: 34199637 PMCID: PMC8229993 DOI: 10.3390/biom11060829] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/30/2021] [Accepted: 05/31/2021] [Indexed: 12/28/2022] Open
Abstract
Endogenous retroviruses (ERVs), previously viewed as deleterious relics of ancestral retrovirus infections, are silenced in the vast majority of cells to minimize the risk of retrotransposition. Counterintuitively, bursts of ERV transcription usually occur during maternal-to-zygotic transition (MZT) in preimplantation embryos; this is regarded as a major landmark event in the zygotic genome activation (ZGA) process, indicating that ERVs play an active part in ZGA. Evolutionarily, the interaction between ERVs and hosts is mutually beneficial. The endogenization of retrovirus sequences rewires the gene regulatory network during ZGA, and ERV repression may lower germline fitness. Unfortunately, owing to various limitations of somatic cell nuclear transfer (SCNT) technology, both developmental arrest and ZGA abnormalities occur in a high percentage of cloned embryos, accompanied by ERV silencing, which may be caused by the activation failure of upstream ERV inducers. In this review, we discuss the functions and regulation of ERVs during the ZGA process and the feasibility of temporal control over ERVs in cloned embryos via exogenous double homeobox (DUX). We hypothesize that further accurate characterization of the ERV-rewired gene regulatory network during ZGA may provide a novel perspective on the development of preimplantation embryos.
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Affiliation(s)
- Bo Fu
- Institute of Animal Husbandry, HeiLongJiang Academy of Agricultural Sciences, Harbin 150086, China; (B.F.); (H.M.)
- Key Laboratory of Combining Farming and Animal Husbandry, Ministry of Agriculture and Rural Affairs, Harbin 150086, China
| | - Hong Ma
- Institute of Animal Husbandry, HeiLongJiang Academy of Agricultural Sciences, Harbin 150086, China; (B.F.); (H.M.)
- Key Laboratory of Combining Farming and Animal Husbandry, Ministry of Agriculture and Rural Affairs, Harbin 150086, China
| | - Di Liu
- Institute of Animal Husbandry, HeiLongJiang Academy of Agricultural Sciences, Harbin 150086, China; (B.F.); (H.M.)
- Key Laboratory of Combining Farming and Animal Husbandry, Ministry of Agriculture and Rural Affairs, Harbin 150086, China
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13
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Kohlrausch FB, Berteli TS, Wang F, Navarro PA, Keefe DL. Control of LINE-1 Expression Maintains Genome Integrity in Germline and Early Embryo Development. Reprod Sci 2021; 29:328-340. [PMID: 33481218 DOI: 10.1007/s43032-021-00461-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 01/06/2021] [Indexed: 11/28/2022]
Abstract
Maintenance of genome integrity in the germline and in preimplantation embryos is crucial for mammalian development. Epigenetic remodeling during primordial germ cell (PGC) and preimplantation embryo development may contribute to genomic instability in these cells, since DNA methylation is an important mechanism to silence retrotransposons. Long interspersed elements 1 (LINE-1 or L1) are the most common autonomous retrotransposons in mammals, corresponding to approximately 17% of the human genome. Retrotransposition events are more frequent in germ cells and in early stages of embryo development compared with somatic cells. It has been shown that L1 activation and expression occurs in germline and is essential for preimplantation development. In this review, we focus on the role of L1 retrotransposon in mouse and human germline and early embryo development and discuss the possible relationship between L1 expression and genomic instability during these stages. Although several studies have addressed L1 expression at different stages of development, the developmental consequences of this expression remain poorly understood. Future research is still needed to highlight the relationship between L1 retrotransposition events and genomic instability during germline and early embryo development.
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Affiliation(s)
- Fabiana B Kohlrausch
- Department of Obstetrics and Gynecology, New York University Langone Medical Center, 462 1st Avenue, New York, NY, 10016, USA.,Departamento de Biologia Geral, Instituto de Biologia, Universidade Federal Fluminense, Niterói, RJ, Brazil
| | - Thalita S Berteli
- Department of Obstetrics and Gynecology, New York University Langone Medical Center, 462 1st Avenue, New York, NY, 10016, USA.,Departamento de Ginecologia e Obstetrícia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Fang Wang
- Department of Obstetrics and Gynecology, New York University Langone Medical Center, 462 1st Avenue, New York, NY, 10016, USA
| | - Paula A Navarro
- Departamento de Ginecologia e Obstetrícia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - David L Keefe
- Department of Obstetrics and Gynecology, New York University Langone Medical Center, 462 1st Avenue, New York, NY, 10016, USA.
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Shalini V, Bhaduri U, Ravikkumar AC, Rengarajan A, Satyanarayana RMR. Genome-wide occupancy reveals the localization of H1T2 (H1fnt) to repeat regions and a subset of transcriptionally active chromatin domains in rat spermatids. Epigenetics Chromatin 2021; 14:3. [PMID: 33407810 PMCID: PMC7788777 DOI: 10.1186/s13072-020-00376-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 11/23/2020] [Indexed: 11/10/2022] Open
Abstract
Background H1T2/H1FNT is a germ cell-specific linker histone variant expressed during spermiogenesis specifically in round and elongating spermatids. Infertile phenotype of homozygous H1T2 mutant male mice revealed the essential function of H1T2 for the DNA condensation and histone-to-protamine replacement in spermiogenesis. However, the mechanism by which H1T2 imparts the inherent polarity within spermatid nucleus including the additional protein partners and the genomic domains occupied by this linker histone are unknown. Results Sequence analysis revealed the presence of Walker motif, SR domains and putative coiled-coil domains in the C-terminal domain of rat H1T2 protein. Genome-wide occupancy analysis using highly specific antibody against the CTD of H1T2 demonstrated the binding of H1T2 to the LINE L1 repeat elements and to a significant percentage of the genic regions (promoter-TSS, exons and introns) of the rat spermatid genome. Immunoprecipitation followed by mass spectrometry analysis revealed the open chromatin architecture of H1T2 occupied chromatin encompassing the H4 acetylation and other histone PTMs characteristic of transcriptionally active chromatin. In addition, the present study has identified the interacting protein partners of H1T2-associated chromatin mainly as nucleo-skeleton components, RNA-binding proteins and chaperones. Conclusions Linker histone H1T2 possesses unique domain architecture which can account for the specific functions associated with chromatin remodeling events facilitating the initiation of histone to transition proteins/protamine transition in the polar apical spermatid genome. Our results directly establish the unique function of H1T2 in nuclear shaping associated with spermiogenesis by mediating the interaction between chromatin and nucleo-skeleton, positioning the epigenetically specialized chromatin domains involved in transcription coupled histone replacement initiation towards the apical pole of round/elongating spermatids.
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Affiliation(s)
- Vasantha Shalini
- From the Chromatin Biology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore, 560064, India
| | - Utsa Bhaduri
- From the Chromatin Biology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore, 560064, India.,Department of Life Sciences, University of Trieste, Trieste, Italy.,European Union's H2020 TRIM-NET ITN, Marie Sklodowska-Curie Actions (MSCA), Leiden, The Netherlands
| | - Anjhana C Ravikkumar
- From the Chromatin Biology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore, 560064, India
| | - Anusha Rengarajan
- From the Chromatin Biology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore, 560064, India
| | - Rao M R Satyanarayana
- From the Chromatin Biology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore, 560064, India.
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15
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Wang J, Huang J, Shi G. Retrotransposons in pluripotent stem cells. CELL REGENERATION 2020; 9:4. [PMID: 32588192 PMCID: PMC7306833 DOI: 10.1186/s13619-020-00046-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/19/2019] [Indexed: 12/18/2022]
Abstract
Transposable elements constitute about half of the mammalian genome, and can be divided into two classes: the class I (retrotransposons) and the class II (DNA transposons). A few hundred types of retrotransposons, which are dynamic and stage specific, have been annotated. The copy numbers and genomic locations are significantly varied in species. Retrotransposons are active in germ cells, early embryos and pluripotent stem cells (PSCs) correlated with low levels of DNA methylation in epigenetic regulation. Some key pluripotency transcriptional factors (such as OCT4, SOX2, and NANOG) bind retrotransposons and regulate their activities in PSCs, suggesting a vital role of retrotransposons in pluripotency maintenance and self-renewal. In response to retrotransposons transposition, cells employ a number of silencing mechanisms, such as DNA methylation and histone modification. This review summarizes expression patterns, functions, and regulation of retrotransposons in PSCs and early embryonic development.
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Affiliation(s)
- Jingwen Wang
- School of Life Sciences, SunYat-sen University, Guangzhou, 510275, P. R. China
| | - Junjiu Huang
- School of Life Sciences, SunYat-sen University, Guangzhou, 510275, P. R. China. .,Key Laboratory of Reproductive Medicine of Guangdong Province, School of Life Sciences and the First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510275, China. .,Key Laboratory of Reproductive Medicine of Guangdong Province, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.
| | - Guang Shi
- School of Life Sciences, SunYat-sen University, Guangzhou, 510275, P. R. China.
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16
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Newkirk SJ, Kong L, Jones MM, Habben CE, Dilts VL, Ye P, An W. Subfamily-specific quantification of endogenous mouse L1 retrotransposons by droplet digital PCR. Anal Biochem 2020; 601:113779. [PMID: 32442414 DOI: 10.1016/j.ab.2020.113779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 05/06/2020] [Accepted: 05/14/2020] [Indexed: 11/18/2022]
Abstract
Long interspersed element type 1 (LINE-1; L1) mobilizes during early embryogenesis, neurogenesis, and germ cell development, accounting for 25% of disease-causing heritable insertions and 98% of somatic insertions in cancer. To better understand the regulation and impact of L1 mobilization in the genome, reliable methods for measuring L1 copy number variation (CNV) are needed. Here we present a comprehensive analysis of a droplet digital PCR (ddPCR) based method for quantifying endogenous mouse L1. We provide experimental evidence that ddPCR assays can be designed to target specific L1 subfamilies using diagnostic single nucleotide polymorphisms (SNPs). The target and off-target L1 subfamilies form distinct droplet clusters, which were experimentally verified using both synthetic gene fragments and endogenous L1 derived plasmid clones. We further provide a roadmap for in silico assay design and evaluation of target specificity, ddPCR testing, and optimization for L1 CNV quantification. The assay can achieve a sensitivity of 5% CNV with 8 technical replicates. With 24 technical replicates, it can detect 2% CNV because of the increased precision. The same approach will serve as a guide for the development of ddPCR based assays for quantifying human L1 copy number and any other high copy genomic target sequences.
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Affiliation(s)
- Simon J Newkirk
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD, 57007, United States.
| | - Lingqi Kong
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD, 57007, United States.
| | - Mason M Jones
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD, 57007, United States.
| | - Chase E Habben
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD, 57007, United States.
| | - Victoria L Dilts
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD, 57007, United States.
| | - Ping Ye
- Department of Pharmacy Practice, South Dakota State University, Brookings, SD, 57007, United States; Avera Research Institute, Sioux Falls, SD, 57108, United States.
| | - Wenfeng An
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD, 57007, United States.
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17
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Ueno M, Matsunaga A, Teratake Y, Ishizaka Y. Retrotransposition and senescence in mouse heart tissue by viral protein R of human immunodeficiency virus-1. Exp Mol Pathol 2020; 114:104433. [PMID: 32243892 DOI: 10.1016/j.yexmp.2020.104433] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 03/23/2020] [Accepted: 03/28/2020] [Indexed: 11/25/2022]
Abstract
Combination antiretroviral therapy (cART) has greatly improved the prognosis of patients with human immunodeficiency virus type-1 (HIV-1) infection. However, cardiovascular disease (CVD) remains a serious issue even in the post-cART era. Viral protein R (Vpr), an accessory gene product of HIV-1, exerts pleiotropic activities such as the induction of DNA damage signals, apoptosis by mitochondrial membrane depolarization, G2/M-phase cell cycle abnormalities, and retrotransposition. Importantly, some of these cellular responses are induced by the trans-acting activity of Vpr. Recently, we established an enzyme-linked immunosorbent assay to detect Vpr and reported that about 22% of blood samples from 100 HIV-1-positive patients were positive for Vpr. Here, we investigated the biological effects of recombinant Vpr (rVpr) in vivo. We observed that repeated injections of rVpr increased the copy number of long interspersed element-1 (L1) in the heart genome in mice. rVpr also increased the number of cells positive for senescence-associated β-galactosidase (SA-β-gal) and fibrosis in the heart. Notably, co-administration of a reverse transcriptase inhibitor reduced the number of rVpr-induced SA-β-gal-positive cells and fibrosis concomitantly with the attenuation of L1 retrotransposition. Interestingly, a Vpr mutant defective for mitochondrial dysfunction also induced heart senescence and increased L1 copy number. Together with a recent report that L1 retrotransposition functions as a molecular basis of senescence, our current data suggest that rVpr-induced L1 retrotransposition is linked with senescence in heart tissue. We would propose that Vpr in the bloodstream may be one of risk factors for CVD, and that its monitoring will lead to well understanding of the heterogeneity and multifactorial mechanisms of CVD in HIV-1 patients.
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Affiliation(s)
- Mikako Ueno
- Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan
| | - Akihiro Matsunaga
- Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan
| | - Yoichi Teratake
- Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan
| | - Yukihito Ishizaka
- Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan.
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18
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Spadafora C. Transgenerational epigenetic reprogramming of early embryos: a mechanistic model. ENVIRONMENTAL EPIGENETICS 2020; 6:dvaa009. [PMID: 32704385 PMCID: PMC7368376 DOI: 10.1093/eep/dvaa009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 05/13/2020] [Accepted: 05/15/2020] [Indexed: 05/10/2023]
Abstract
The notion that epigenetic information can be transmitted across generations is supported by mounting waves of data, but the underlying mechanisms remain elusive. Here, a model is proposed which combines different lines of experimental evidence. First, it has been shown that somatic tissues exposed to stressing stimuli release circulating RNA-containing extracellular vesicles; second, epididymal spermatozoa can take up, internalize and deliver the RNA-containing extracellular vesicles to oocytes at fertilization; third, early embryos can process RNA-based information. These elements constitute the building blocks upon which the model is built. The model proposes that a continuous stream of epigenetic information flows from parental somatic tissues to the developing embryos. The flow can cross the Weismann barrier, is mediated by circulating vesicles and epididymal spermatozoa, and has the potential to generate epigenetic traits that are then stably acquired in the offspring. In a broader perspective, it emerges that a natural 'assembly line' operates continuously, aiming at passing the parental epigenetic blueprint in growing embryos.
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Affiliation(s)
- Corrado Spadafora
- Institute of Translational Pharmacology, National Research Council (CNR), 100 Via del Fosso del Cavaliere, 00133 Rome, Italy
- Correspondence address. Institute of Translational Pharmacology, National Research Council (CNR), 100 Via del Fosso del Cavaliere, 00133 Rome, Italy. Tel: +39 0649917536; Fax: +39 064457529; E-mail: ;
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19
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Aschacher T, Wolf B, Aschacher O, Enzmann F, Laszlo V, Messner B, Türkcan A, Weis S, Spiegl-Kreinecker S, Holzmann K, Laufer G, Ehrlich M, Bergmann M. Long interspersed element-1 ribonucleoprotein particles protect telomeric ends in alternative lengthening of telomeres dependent cells. Neoplasia 2019; 22:61-75. [PMID: 31846834 PMCID: PMC6920197 DOI: 10.1016/j.neo.2019.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 12/21/2022] Open
Abstract
Malignant cells ensure telomere maintenance by the alternative lengthening of telomeres (ALT) in the absence of telomerase activity (TA). The retrotransposons "long interspersed nuclear element-1" (LINE-1, L1) are expressed in malignant cells and are primarily known to contribute to complex karyotypes. Here we demonstrate that LINE-1 ribonucleoprotein particles (L1-RNPs) expression is significantly higher in ALT+- versus in TA+-human glioma. Analyzing a role of L1-RNP in ALT, we show that L1-RNPs bind to telomeric repeat containing RNA (TERRA), which is critical for telomere stabilization and which is overexpressed in ALT+ cells. In turn, L1-RNP knockdown (KD) abrogated the nuclear retention of TERRA, resulted in increased telomeric DNA damage, decreased cell growth and reduced expression of ALT characteristics such as c-circles and PML-bodies. L1-RNP KD also decreased the expression of Shelterin- and the ALT-regulating protein Topoisomerase IIIα (TopoIIIα) indicating a more general role of L1-RNPs in supporting telomeric integrity in ALT. Our findings suggest an impact of L1-RNP on telomere stability in ALT+ dependent tumor cells. As L1-RNPs are rarely expressed in normal adult human tissue those elements might serve as a novel target for tumor ablative therapy.
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Affiliation(s)
- Thomas Aschacher
- Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Brigitte Wolf
- Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Olivia Aschacher
- Department of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Florian Enzmann
- Department of Vascular and Endovascular Surgery, Paracelsus Medical University Salzburg, Muellner Hauptstraße 48, 5020 Salzburg, Austria
| | - Viktoria Laszlo
- Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Barbara Messner
- Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Adrian Türkcan
- Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Serge Weis
- Division of Neuropathology, Neuromed Campus, Kepler University Hospital, 4020 Linz, Austria
| | - Sabine Spiegl-Kreinecker
- University Clinic for Neurosurgery, Neuromed Campus, Kepler University Hospital, Johannes Kepler University, Linz, Austria
| | - Klaus Holzmann
- Department of Cancer Research, Borschkegasse 8a, 1090 Vienna, Austria; Comprehensive Cancer Centre, Medical University of Vienna, Austria
| | - Günther Laufer
- Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Marek Ehrlich
- Cardiac Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Michael Bergmann
- Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria; Comprehensive Cancer Centre, Medical University of Vienna, Austria.
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20
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Bedrosian TA, Quayle C, Novaresi N, Gage FH. Early life experience drives structural variation of neural genomes in mice. Science 2018; 359:1395-1399. [DOI: 10.1126/science.aah3378] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Revised: 11/04/2017] [Accepted: 01/25/2018] [Indexed: 12/19/2022]
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21
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The "evolutionary field" hypothesis. Non-Mendelian transgenerational inheritance mediates diversification and evolution. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 134:27-37. [PMID: 29223657 DOI: 10.1016/j.pbiomolbio.2017.12.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 11/17/2017] [Accepted: 12/05/2017] [Indexed: 12/23/2022]
Abstract
Epigenetics is increasingly regarded as a potential contributing factor to evolution. Building on apparently unrelated results, here I propose that RNA-containing nanovesicles, predominantly small regulatory RNAs, are released from somatic tissues in the bloodstream, cross the Weismann barrier, reach the epididymis, and are eventually taken up by spermatozoa; henceforth the information is delivered to oocytes at fertilization. In the model, a LINE-1-encoded reverse transcriptase activity, present in spermatozoa and early embryos, plays a key role in amplifying and propagating these RNAs as extrachromosomal structures. It may be conceived that, over generations, the cumulative effects of sperm-delivered RNAs would cross a critical threshold and overcome the buffering capacity of embryos. As a whole, the process can promote the generation of an information-containing platform that drives the reshaping of the embryonic epigenetic landscape with the potential to generate ontogenic changes and redirect the evolutionary trajectory. Over time, evolutionary significant, stably acquired variations could be generated through the process. The interplay between these elements defines the concept of "evolutionary field", a self-consistent, comprehensive information-containing platform and a source of discontinuous evolutionary novelty.
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22
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Spadafora C. Sperm-Mediated Transgenerational Inheritance. Front Microbiol 2017; 8:2401. [PMID: 29255455 PMCID: PMC5722983 DOI: 10.3389/fmicb.2017.02401] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/20/2017] [Indexed: 11/18/2022] Open
Abstract
Spermatozoa of virtually all species can spontaneously take up exogenous DNA or RNA molecules and internalize them into nuclei. In this article I review evidence for a key role of a reverse transcriptase (RT) activity, encoded by LINE-1 retrotransposons, in the fate of the internalized nucleic acid molecules and their implication in transgenerational inheritance. LINE-1-derived RT, present in sperm heads, can reverse-transcribe the internalized molecules in cDNA copies: exogenous RNA is reverse-transcribed in a one-step reaction, whereas DNA is first transcribed into RNA and subsequently reverse-transcribed. Both RNA and cDNA molecules can be delivered from sperm cells to oocytes at fertilization, further propagated throughout embryogenesis and inherited in a non-Mendelian fashion in tissues of adult animals. The reverse-transcribed sequences are extrachromosomal, low-abundance, and mosaic distributed in tissues of adult individuals, where they are variably expressed. These “retrogenes” are transcriptionally competent and induce novel phenotypic traits in animals. Growing evidence indicate that cancer tissues produce DNA- and RNA-containing exosomes. We recently found that these exosomes are released in the bloodstream and eventually taken up into epididymal spermatozoa, consistent with the emerging view that a transgenerational flow of extrachromosomal RNA connects soma to germline and, further, to next generation embryos. Spermatozoa play a crucial bridging role in this process: they act as collectors of somatic information and as delivering vectors to the next generation. On the whole, this phenomenon is compatible with a Lamarckian-type view and closely resembles Darwinian pangenesis.
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Affiliation(s)
- Corrado Spadafora
- Institute of Translational Pharmacology, National Research Council of Italy, Rome, Italy
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23
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Vasilyev SA, Tolmacheva EN, Lebedev IN. Epigenetic regulation and role of LINE-1 retrotransposon in embryogenesis. RUSS J GENET+ 2016. [DOI: 10.1134/s1022795416120152] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ueno M, Okamura T, Mishina M, Ishizaka Y. Modulation of long interspersed nuclear element-1 in the mouse hippocampus during maturation. Mob Genet Elements 2016; 6:e1211980. [PMID: 27583186 DOI: 10.1080/2159256x.2016.1211980] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 07/06/2016] [Accepted: 07/06/2016] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND Retrotransposition of long interspersed nuclear element-1 (L1-RTP) is proposed to contribute to central nervous system (CNS) plasticity by inducing mosaicism of neuronal cells. Clinical studies have identified increased L1 copy numbers in the brains of patients with psychiatric disorders. These observations implicate that L1-RTP is important for neurogenesis and that its deregulation represents a risk factor for mental disorders. However, no supportive evidence is available for understanding the importance of L1-RTP in CNS function. FINDINGS To explore the physiological role of L1-RTP in CNS, we examined the L1 copy number during maturation. Interestingly, the L1 copy number increased after birth in the mouse hippocampus, but not the frontal lobe, with maximal copy numbers found in 8-week-old mice. This age-dependent L1 increase was abolished by administration of a reverse-transcriptase inhibitor, stavudine (d4T), which showed no toxic effects. Notably, the age-dependent L1 increase was attenuated by post-weaning social isolation (SI) stress, a well-known intervention for inducing psychiatric disorders in mice, or deletion of the NR2A gene that encodes a subunit of the glutamate receptor. Moreover, the negative effects of SI stress on L1-RTP were partially restored by environmental enrichment with voluntary running, but not by fluoxetine, a commonly used anti-psychiatric drug. Finally, behavioral experiments revealed that learning memory was defective in d4T-treated mice, which was similarly observed in mice raised under SI stress. CONCLUSION We detected the modulation of L1-RTP in the hippocampus during maturation of the CNS. In a recent study, we demonstrated that stimulants such as methamphetamine and cocaine were active in the induction of L1-RTP in neuronal cells, and previous studies have shown that NR2A-deficient mice are susceptible to mental abnormality. Herein, our data support the notion that the age-dependent modulation of L1-RTP is involved in genome differentiation in the hippocampus, and that modulation defects are linked to the development of psychiatric disorders.
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Affiliation(s)
- Mikako Ueno
- Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine , Shinjuku-ku, Tokyo Japan
| | - Tadashi Okamura
- Department of Laboratory Animal Medicine, Research Institute, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo, Japan; Section of Animal Models, Department of Infectious Diseases, Research Institute, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo, Japan
| | - Masayoshi Mishina
- Brain Science Laboratory, The Research Organization of Science and Technology, Ritsumeikan University , Kusatsu, Shiga, Japan
| | - Yukihito Ishizaka
- Department of Intractable Diseases, Research Institute, National Center for Global Health and Medicine , Shinjuku-ku, Tokyo Japan
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25
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Spadafora C. Soma to germline inheritance of extrachromosomal genetic information via a LINE-1 reverse transcriptase-based mechanism. Bioessays 2016; 38:726-33. [DOI: 10.1002/bies.201500197] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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26
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Poltronieri P, Sun B, Mallardo M. RNA Viruses: RNA Roles in Pathogenesis, Coreplication and Viral Load. Curr Genomics 2016; 16:327-35. [PMID: 27047253 PMCID: PMC4763971 DOI: 10.2174/1389202916666150707160613] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Revised: 04/10/2015] [Accepted: 04/14/2015] [Indexed: 01/30/2023] Open
Abstract
The review intends to present and recapitulate the current knowledge on the roles and importance of regulatory RNAs, such as microRNAs and small interfering RNAs, RNA binding proteins and enzymes processing RNAs or activated by RNAs, in cells infected by RNA viruses. The review focuses on how non-coding RNAs are involved in RNA virus replication, pathogenesis and host response, especially in retroviruses HIV, with examples of the mechanisms of action, transcriptional regulation, and promotion of increased stability of their targets or their degradation.
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Affiliation(s)
- Palmiro Poltronieri
- CNR-ISPA, Institute of Sciences of Food Productions, National Research Council of Italy, Lecce, Italy
| | - Binlian Sun
- Research Group of HIV Molecular Epidemiology and Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei 430071, PR China
| | - Massimo Mallardo
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II°, Napoli, Italy
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Russell SJ, Stalker L, Gilchrist G, Backx A, Molledo G, Foster RA, LaMarre J. Identification of PIWIL1 Isoforms and Their Expression in Bovine Testes, Oocytes, and Early Embryos. Biol Reprod 2016; 94:75. [PMID: 26911426 DOI: 10.1095/biolreprod.115.136721] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 02/11/2016] [Indexed: 12/21/2022] Open
Abstract
PIWI proteins are members of the larger Argonaute family and bind to specific 24-32 nucleotide RNAs called PIWI-interacting RNAs (piRNAs). PIWI-interacting RNAs direct PIWI-mediated suppression of retrotransposon expression in the male germline in humans and mice, but their roles in bovine reproduction and embryogenesis are unknown. Although the majority of research in mammals has focused on the functions of PIWI proteins during spermatogenesis, this family of proteins and their associated piRNAs have recently been identified in early embryos. The goals of this study were to characterize the expression of PIWIL1 in bovine testis, oocytes, and early embryos. A full-lengthPIWIL1transcript and protein was found in the testis, specifically in the germs cells of mature seminiferous tubules. RNA-immunoprecipitation demonstrated the presence of putative piRNAs with a mean length of 30 nucleotides bound to PIWIL1 in testes. 3'-Rapid amplification of cDNA ends analysis ofPIWIL1transcripts in testes and oocytes revealed two shorter isoforms in addition to the full-length transcript that was only present in testes. TruncatedPIWIL1isoforms in oocytes and testes were confirmed through amplification of their unique intronic fragments. Expression profiling ofPIWIL1through early embryogenesis demonstrated peak mRNA expression at the 2-cell stage with decreasing levels through to the blastocyst. PIWIL1-YFP fusion plasmids were produced for each isoform and expressed in HEK 293 cells, demonstrating nuclear exclusion and size-specific banding of the different isoforms. These data represent the first comprehensive characterization of PIWIL1 in bovine, revealing functional similarities with PIWIL1 in other species and suggest tissue-specific expression of several isoforms.
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Affiliation(s)
- Stewart J Russell
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Leanne Stalker
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Graham Gilchrist
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Alanna Backx
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Gonzalo Molledo
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Robert A Foster
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - Jonathan LaMarre
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
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28
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Sciamanna I, De Luca C, Spadafora C. The Reverse Transcriptase Encoded by LINE-1 Retrotransposons in the Genesis, Progression, and Therapy of Cancer. Front Chem 2016; 4:6. [PMID: 26904537 PMCID: PMC4749692 DOI: 10.3389/fchem.2016.00006] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 01/26/2016] [Indexed: 12/24/2022] Open
Abstract
In higher eukaryotic genomes, Long Interspersed Nuclear Element 1 (LINE-1) retrotransposons represent a large family of repeated genomic elements. They transpose using a reverse transcriptase (RT), which they encode as part of the ORF2p product. RT inhibition in cancer cells, either via RNA interference-dependent silencing of active LINE-1 elements, or using RT inhibitory drugs, reduces cancer cell proliferation, promotes their differentiation and antagonizes tumor progression in animal models. Indeed, the non-nucleoside RT inhibitor efavirenz has recently been tested in a phase II clinical trial with metastatic prostate cancer patients. An in-depth analysis of ORF2p in a mouse model of breast cancer showed ORF2p to be precociously expressed in precancerous lesions and highly abundant in advanced cancer stages, while being barely detectable in normal breast tissue, providing a rationale for the finding that RT-expressing tumors are therapeutically sensitive to RT inhibitors. We summarize mechanistic and gene profiling studies indicating that abundant LINE-1-derived RT can “sequester” RNA substrates for reverse transcription in tumor cells, entailing the formation of RNA:DNA hybrid molecules and impairing the overall production of regulatory miRNAs, with a global impact on the cell transcriptome. Based on these data, LINE-1-ORF2 encoded RT has a tumor-promoting potential that is exerted at an epigenetic level. We propose a model whereby LINE1-RT drives a previously unrecognized global regulatory process, the deregulation of which drives cell transformation and tumorigenesis with possible implications for cancer cell heterogeneity.
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Affiliation(s)
| | | | - Corrado Spadafora
- Institute of Translational Pharmacology, National Resarch Council of Italy Rome, Italy
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29
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A protein domain-based view of the virosphere–host relationship. Biochimie 2015; 119:231-43. [DOI: 10.1016/j.biochi.2015.08.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 08/15/2015] [Indexed: 11/20/2022]
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30
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Yamamoto R, Abe KI, Suzuki Y, Suzuki MG, Aoki F. Characterization of gene expression in mouse embryos at the 1-cell stage. J Reprod Dev 2015; 62:87-92. [PMID: 26599803 PMCID: PMC4768782 DOI: 10.1262/jrd.2015-131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In mice, transcription from the zygotic genome is initiated at the mid-1-cell stage after fertilization.
Although a recent high-throughput sequencing (HTS) analysis revealed that this transcription occurs
promiscuously throughout almost the entire genome in 1-cell stage embryos, a detailed investigation of this
process has yet to be conducted using protein-coding genes. Thus, the present study utilized previous RNA
sequencing (RNAseq) data to determine the characteristics and regulatory regions of genes transcribed at the
1-cell stage. While the expression patterns of protein-coding genes of mouse embryos were very different at
the 1-cell stage than at other stages and in various tissues, an analysis for the upstream and downstream
regions of actively expressed genes did not reveal any elements that were specific to 1-cell stage embryos.
Therefore, the unique gene expression pattern observed at the 1-cell stage in mouse embryos appears to be
governed by mechanisms independent of a specific promoter element.
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Affiliation(s)
- Ryoma Yamamoto
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8562, Japan
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31
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Double strand break repair by capture of retrotransposon sequences and reverse-transcribed spliced mRNA sequences in mouse zygotes. Sci Rep 2015. [PMID: 26216318 PMCID: PMC4516963 DOI: 10.1038/srep12281] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The CRISPR/Cas system efficiently introduces double strand breaks (DSBs) at a genomic locus specified by a single guide RNA (sgRNA). The DSBs are subsequently repaired through non-homologous end joining (NHEJ) or homologous recombination (HR). Here, we demonstrate that DSBs introduced into mouse zygotes by the CRISPR/Cas system are repaired by the capture of DNA sequences deriving from retrotransposons, genomic DNA, mRNA and sgRNA. Among 93 mice analysed, 57 carried mutant alleles and 22 of them had long de novo insertion(s) at DSB-introduced sites; two were spliced mRNAs of Pcnt and Inadl without introns, indicating the involvement of reverse transcription (RT). Fifteen alleles included retrotransposons, mRNAs, and other sequences without evidence of RT. Two others were sgRNAs with one containing T7 promoter-derived sequence suggestive of a PCR product as its origin. In conclusion, RT-product-mediated DSB repair (RMDR) and non-RMDR repair were identified in the mouse zygote. We also confirmed that both RMDR and non-RMDR take place in CRISPR/Cas transfected NIH-3T3 cells. Finally, as two de novo MuERV-L insertions in C57BL/6 mice were shown to have characteristic features of RMDR in natural conditions, we hypothesize that RMDR contributes to the emergence of novel DNA sequences in the course of evolution.
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32
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Sciamanna I, Gualtieri A, Piazza PF, Spadafora C. Regulatory roles of LINE-1-encoded reverse transcriptase in cancer onset and progression. Oncotarget 2015; 5:8039-51. [PMID: 25478632 PMCID: PMC4226666 DOI: 10.18632/oncotarget.2504] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
LINE-1 retrotransposons encode the reverse transcriptase (RT) enzyme, required for their own mobility, the expression of which is inhibited in differentiated tissues while being active in tumors. Experimental evidence indicate that the inhibition of LINE-1-derived RT restores differentiation in cancer cells, inhibits tumor progression and yields globally reprogrammed transcription profiles. Newly emerging data suggest that LINE-1-encoded RT modulates the biogenesis of miRNAs, by governing the balance between the production of regulatory double-stranded RNAs and RNA:DNA hybrid molecules, with a direct impact on global gene expression. Abnormally high RT activity unbalances the transcriptome in cancer cells, while RT inhibition restores ‘normal’ miRNA profiles and their regulatory networks. This RT-dependent mechanism can target the myriad of transcripts - both coding and non-coding, sense and antisense - in eukaryotic transcriptomes, with a profound impact on cell fates. LINE-1-encoded RT emerges therefore as a key regulator of a previously unrecognized mechanism in tumorigenesis
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33
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Aschacher T, Wolf B, Enzmann F, Kienzl P, Messner B, Sampl S, Svoboda M, Mechtcheriakova D, Holzmann K, Bergmann M. LINE-1 induces hTERT and ensures telomere maintenance in tumour cell lines. Oncogene 2015; 35:94-104. [PMID: 25798839 DOI: 10.1038/onc.2015.65] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 01/17/2015] [Accepted: 01/30/2015] [Indexed: 12/28/2022]
Abstract
A hallmark of cancer cells is an activated telomere maintenance mechanism, which allows prolonged survival of the malignant cells. In more than 80% of tumours, telomeres are elongated by the enzyme telomerase, which adds de novo telomere repeats to the ends of chromosomes. Cancer cells are also characterized by expression of active LINE-1 elements (L1s, long interspersed nuclear elements-1). L1 elements are abundant retrotransposons in the eukaryotic genome that are primarily known for facilitating aberrant recombination. Using L1-knockdown (KD), we show for the first time that L1 is critical for telomere maintenance in telomerase-positive tumour cells. The reduced length of telomeres in the L1-KD-treated cells correlated with an increased rate of telomere dysfunction foci, a reduced expression of shelterin proteins and an increased rate of anaphase bridges. The decreased telomere length was associated with a decreased telomerase activity and decreased telomerase mRNA level; the latter was increased upon L1 overexpression. L1-KD also led to a decrease in mRNA and protein expression of cMyc and KLF-4, two main transcription factors of telomerase and altered mRNA levels of other stem-cell-associated proteins such as CD44 and hMyb, as well as a corresponding reduced growth of spheroids. The KD of KLF-4 or cMyc decreased the level of L1-ORF1 mRNA, suggesting a specific reciprocal regulation with L1. Thus, our findings contribute to the understanding of L1 as a pathogenicity factor in cancer cells. As L1 is only expressed in pathophysiological conditions, L1 now appears to be target in the rational treatment of telomerase-positive cancer.
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Affiliation(s)
- T Aschacher
- Cardiac Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - B Wolf
- Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - F Enzmann
- Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - P Kienzl
- Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - B Messner
- Cardiac Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - S Sampl
- Department of Medicine I, Institute of Cancer Research, Vienna, Austria
| | - M Svoboda
- Department of Pathophysiology, Medical University of Vienna, Vienna, Austria
| | - D Mechtcheriakova
- Department of Pathophysiology, Medical University of Vienna, Vienna, Austria.,Comprehensive Cancer Center Vienna, Vienna, Austria
| | - K Holzmann
- Department of Medicine I, Institute of Cancer Research, Vienna, Austria.,Comprehensive Cancer Center Vienna, Vienna, Austria
| | - M Bergmann
- Surgery Research Laboratory, Department of Surgery, Medical University of Vienna, Vienna, Austria.,Comprehensive Cancer Center Vienna, Vienna, Austria
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34
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Spadafora C. A LINE-1-encoded reverse transcriptase-dependent regulatory mechanism is active in embryogenesis and tumorigenesis. Ann N Y Acad Sci 2015; 1341:164-71. [PMID: 25586649 DOI: 10.1111/nyas.12637] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
LINE-1 (long interspersed nuclear elements) retrotransposons constitute a large family of retrotransposable elements, accounting for 17% of the human genome. They encode proteins required for their own mobilization, including a reverse transcriptase (RT) enzyme highly expressed in mouse embryos and mouse and human cancer cells and repressed in somatic differentiated healthy cells. We have found that reverse transcription takes place in early murine embryos, yielding an increase in LINE-1 copy number during preimplantation development, which also occurs in tumor progression. RT inhibition irreversibly arrests embryo development, reduces cancer cell proliferation, promotes differentiation, antagonizes tumor growth, and causes a global reprogramming of transcription profiles. These results strongly suggest that a previously unrecognized RT-dependent regulatory mechanism operates during preimplantation development, is repressed during differentiation to normal tissues, and, when erroneously reactivated in adult life, promotes cell transformation and cancer progression by "resurrecting" embryonic transcriptional pathways. The RT-dependent mechanism emerges as a major source of genetic and epigenetic changes with physiological, pathological, and evolutionary implications.
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Affiliation(s)
- Corrado Spadafora
- Istituto Superiore di Sanità, Rome, Italy; CNR Institute of Translational Pharmacology, Rome, Italy
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35
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Sciamanna I, Gualtieri A, Cossetti C, Osimo EF, Ferracin M, Macchia G, Aricò E, Prosseda G, Vitullo P, Misteli T, Spadafora C. A tumor-promoting mechanism mediated by retrotransposon-encoded reverse transcriptase is active in human transformed cell lines. Oncotarget 2014; 4:2271-87. [PMID: 24345856 PMCID: PMC3926826 DOI: 10.18632/oncotarget.1403] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
LINE-1 elements make up the most abundant retrotransposon family in the human genome. Full-length LINE-1 elements encode a reverse transcriptase (RT) activity required for their own retrotranpsosition as well as that of non-autonomous Alu elements. LINE-1 are poorly expressed in normal cells and abundantly in cancer cells. Decreasing RT activity in cancer cells, by either LINE-1-specific RNA interference, or by RT inhibitory drugs, was previously found to reduce proliferation and promote differentiation and to antagonize tumor growth in animal models. Here we have investigated how RT exerts these global regulatory functions. We report that the RT inhibitor efavirenz (EFV) selectively downregulates proliferation of transformed cell lines, while exerting only mild effects on non-transformed cells; this differential sensitivity matches a differential RT abundance, which is high in the former and undetectable in the latter. Using CsCl density gradients, we selectively identify Alu and LINE-1 containing DNA:RNA hybrid molecules in cancer but not in normal cells. Remarkably, hybrid molecules fail to form in tumor cells treated with EFV under the same conditions that repress proliferation and induce the reprogramming of expression profiles of coding genes, microRNAs (miRNAs) and ultraconserved regions (UCRs). The RT-sensitive miRNAs and UCRs are significantly associated with Alu sequences. The results suggest that LINE-1-encoded RT governs the balance between single-stranded and double-stranded RNA production. In cancer cells the abundant RT reverse-transcribes retroelement-derived mRNAs forming RNA:DNA hybrids. We propose that this impairs the formation of double-stranded RNAs and the ensuing production of small regulatory RNAs, with a direct impact on gene expression. RT inhibition restores the ‘normal’ small RNA profile and the regulatory networks that depend on them. Thus, the retrotransposon-encoded RT drives a previously unrecognized mechanism crucial to the transformed state in tumor cells.
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Affiliation(s)
- Ilaria Sciamanna
- Istituto Superiore di Sanità, Viale Regina Elena 299, Rome, Italy
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36
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Del Re B, Giorgi G. Cell-host, LINE and environment: Three players in search of a balance. Mob Genet Elements 2014; 3:e24040. [PMID: 23734298 PMCID: PMC3655780 DOI: 10.4161/mge.24040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 02/13/2013] [Accepted: 02/18/2013] [Indexed: 12/19/2022] Open
Abstract
Long interspersed nuclear elements -1 (LINEs, L1s) are retroelements occupying almost 17% of the human genome. L1 retrotransposition can cause deleterious effects on the host-cell and it is generally inhibited by suppressive mechanisms, but it can occur in some specific cells during early development as well as in some tumor cells and in the presence of several environmental factors. In a recent publication we reported that extremely low frequency pulsed magnetic field can affect L1 retrotransposition in neuroblastoma cells. In this commentary we discuss the interaction between environment and L1 activity in the light of the new emerging paradigm of host-LINE relationship.
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Affiliation(s)
- Brunella Del Re
- Department of Pharmacy and Biotechnology; University of Bologna; Bologna, Italy
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37
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Increased expression and copy number amplification of LINE-1 and SINE B1 retrotransposable elements in murine mammary carcinoma progression. Oncotarget 2014; 4:1882-93. [PMID: 24231191 PMCID: PMC3875756 DOI: 10.18632/oncotarget.1188] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In higher eukaryotic genomes, Long Interspersed Nuclear Element 1 (LINE-1) retrotransposons and endogenous retroviruses represent large families of repeated elements encoding reverse transcriptase (RT) proteins. Short Interspersed Nuclear Element B1 (SINE B1) retrotrasposons do not encode RT, but use LINE-1-derived RT for their retrotransposition. We previously showed that many cancer types have an abundant endogenous RT activity. Inhibition of that activity, by either RNA interference-dependent silencing of active LINE-1 elements or by RT inhibitory drugs, reduced proliferation and promoted differentiation in cancer cells, indicating that LINE-1-encoded RT is required for tumor progression. Using MMTV-PyVT transgenic mice as a well-defined model of breast cancer progression, we now report that both LINE-1 and SINE B1 retrotransposons are up-regulated at a very early stage of tumorigenesis; LINE-1-encoded RT product and enzymatic activity were detected in tumor tissues as early as stage 1, preceding the widespread appearance of histological alterations and specific cancer markers, and further increased in later progression stages, while neither was present in non-pathological breast tissues. Importantly, both LINE-1 and SINE B1 retrotransposon families undergo copy number amplification during tumor progression. These findings therefore indicate that RT activity is distinctive of breast cancer cells and that, furthermore, LINE-1 and SINE B1 undergo copy number amplification during cancer progression.
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38
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LINE-1 retrotransposons: from 'parasite' sequences to functional elements. J Appl Genet 2014; 56:133-45. [PMID: 25106509 DOI: 10.1007/s13353-014-0241-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 07/24/2014] [Accepted: 07/25/2014] [Indexed: 10/24/2022]
Abstract
Long interspersed nuclear elements-1 (LINE-1) are the most abundant and active retrotransposons in the mammalian genomes. Traditionally, the occurrence of LINE-1 sequences in the genome of mammals has been explained by the selfish DNA hypothesis. Nevertheless, recently, it has also been argued that these sequences could play important roles in these genomes, as in the regulation of gene expression, genome modelling and X-chromosome inactivation. The non-random chromosomal distribution is a striking feature of these retroelements that somehow reflects its functionality. In the present study, we have isolated and analysed a fraction of the open reading frame 2 (ORF2) LINE-1 sequence from three rodent species, Cricetus cricetus, Peromyscus eremicus and Praomys tullbergi. Physical mapping of the isolated sequences revealed an interspersed longitudinal AT pattern of distribution along all the chromosomes of the complement in the three genomes. A detailed analysis shows that these sequences are preferentially located in the euchromatic regions, although some signals could be detected in the heterochromatin. In addition, a coincidence between the location of imprinted gene regions (as Xist and Tsix gene regions) and the LINE-1 retroelements was also observed. According to these results, we propose an involvement of LINE-1 sequences in different genomic events as gene imprinting, X-chromosome inactivation and evolution of repetitive sequences located at the heterochromatic regions (e.g. satellite DNA sequences) of the rodents' genomes analysed.
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39
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Miousse IR, Shao L, Chang J, Feng W, Wang Y, Allen AR, Turner J, Stewart B, Raber J, Zhou D, Koturbash I. Exposure to low-dose (56)Fe-ion radiation induces long-term epigenetic alterations in mouse bone marrow hematopoietic progenitor and stem cells. Radiat Res 2014; 182:92-101. [PMID: 24960414 DOI: 10.1667/rr13580.1] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
There is an increasing need to better understand the long-term health effects of high-linear energy transfer (LET) radiation due to exposure during space missions, as well as its increasing use in clinical treatments. Previous studies have indicated that exposure to (56)Fe heavy ions increases the incidence of acute myeloid leukemia (AML) in mice but the underlying molecular mechanisms remain elusive. Epigenetic alterations play a role in radiation-induced genomic instability and the initiation and progression of AML. In this study, we assessed the effects of low-dose (56)Fe-ion irradiation on epigenetic alterations in bone marrow mononuclear cells (BM-MNCs) and hematopoietic progenitor and stem cells (HPSCs). Exposure to (56)Fe ions (600 MeV, 0.1, 0.2 and 0.4 Gy) resulted in significant epigenetic alterations involving methylation of DNA, the DNA methylation machinery and expression of repetitive elements. Four weeks after irradiation, these changes were primarily confined to HPSCs and were exhibited as dose-dependent hypermethylation of LINE1 and SINE B1 repetitive elements [4.2-fold increase in LINE1 (P < 0.001) and 7.6-fold increase in SINE B1 (P < 0.01) after exposure to 0.4 Gy; n = 5]. Epigenetic alterations were persistent and detectable for at least 22 weeks after exposure, when significant loss of global DNA hypomethylation (1.9-fold, P < 0.05), decreased expression of Dnmt1 (1.9-fold, P < 0.01), and increased expression of LINE1 and SINE B1 repetitive elements (2.8-fold, P < 0.001 for LINE1 and 1.9-fold, P < 0.05 for SINE B1; n = 5) were observed after exposure to 0.4 Gy. In contrast, exposure to (56)Fe ions did not result in accumulation of increased production of reactive oxygen species (ROS) and DNA damage, exhibited as DNA strand breaks. Furthermore, no significant alterations in cellular senescence and apoptosis were detected in HPSCs after exposure to (56)Fe-ion radiation. These findings suggest that epigenetic reprogramming is possibly involved in the development of radiation-induced genomic instability and thus, may have a causative role in the development of AML.
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Affiliation(s)
- Isabelle R Miousse
- Department of Environmental and Occupational Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Lijian Shao
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Jianhui Chang
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Wei Feng
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Yingying Wang
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Antiño R Allen
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas.,Department of Neurological Surgery, University of California San Francisco, San Francisco, California
| | - Jennifer Turner
- Department of Behavioral Neuroscience, ONPRC, Oregon Health and Science University, Portland, Oregon
| | - Blair Stewart
- Department of Behavioral Neuroscience, ONPRC, Oregon Health and Science University, Portland, Oregon
| | - Jacob Raber
- Department of Behavioral Neuroscience, ONPRC, Oregon Health and Science University, Portland, Oregon.,Department of Neurology, ONPRC, Oregon Health and Science University, Portland, Oregon.,Department of Division of Neuroscience, ONPRC, Oregon Health and Science University, Portland, Oregon
| | - Daohong Zhou
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Igor Koturbash
- Department of Environmental and Occupational Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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40
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Srivastava A, Philip VM, Greenstein I, Rowe LB, Barter M, Lutz C, Reinholdt LG. Discovery of transgene insertion sites by high throughput sequencing of mate pair libraries. BMC Genomics 2014; 15:367. [PMID: 24884803 PMCID: PMC4035081 DOI: 10.1186/1471-2164-15-367] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 05/06/2014] [Indexed: 01/31/2023] Open
Abstract
Background Transgenesis by random integration of a transgene into the genome of a zygote has become a reliable and powerful method for the creation of new mouse strains that express exogenous genes, including human disease genes, tissue specific reporter genes or genes that allow for tissue specific recombination. Nearly 6,500 transgenic alleles have been created by random integration in embryos over the last 30 years, but for the vast majority of these strains, the transgene insertion sites remain uncharacterized. Results To obtain a complete understanding of how insertion sites might contribute to phenotypic outcomes, to more cost effectively manage transgenic strains, and to fully understand mechanisms of instability in transgene expression, we’ve developed methodology and a scoring scheme for transgene insertion site discovery using high throughput sequencing data. Conclusions Similar to other molecular approaches to transgene insertion site discovery, high-throughput sequencing of standard paired-end libraries is hindered by low signal to noise ratios. This problem is exacerbated when the transgene consists of sequences that are also present in the host genome. We’ve found that high throughput sequencing data from mate-pair libraries are more informative when compared to data from standard paired end libraries. We also show examples of the genomic regions that harbor transgenes, which have in common a preponderance of repetitive sequences. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-367) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anuj Srivastava
- Computational Sciences, The Jackson Laboratory, Bar Harbor, ME USA.
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Schoorlemmer J, Pérez-Palacios R, Climent M, Guallar D, Muniesa P. Regulation of Mouse Retroelement MuERV-L/MERVL Expression by REX1 and Epigenetic Control of Stem Cell Potency. Front Oncol 2014; 4:14. [PMID: 24567914 PMCID: PMC3915180 DOI: 10.3389/fonc.2014.00014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 01/21/2014] [Indexed: 11/17/2022] Open
Abstract
About half of the mammalian genome is occupied by DNA sequences that originate from transposable elements. Retrotransposons can modulate gene expression in different ways and, particularly retrotransposon-derived long terminal repeats, profoundly shape expression of both surrounding and distant genomic loci. This is especially important in pre-implantation development, during which extensive reprograming of the genome takes place and cells pass through totipotent and pluripotent states. At this stage, the main mechanism responsible for retrotransposon silencing, i.e., DNA methylation, is inoperative. A particular retrotransposon called muERV-L/MERVL is expressed during pre-implantation stages and contributes to the plasticity of mouse embryonic stem cells. This review will focus on the role of MERVL-derived sequences as controlling elements of gene expression specific for pre-implantation development, two-cell stage-specific gene expression, and stem cell pluripotency, the epigenetic mechanisms that control their expression, and the contributions of the pluripotency marker REX1 and the related Yin Yang 1 family of transcription factors to this regulation process.
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Affiliation(s)
- Jon Schoorlemmer
- Regenerative Medicine Program, Instituto Aragonés de Ciencias de la Salud , Zaragoza , Spain ; ARAID Foundation , Zaragoza , Spain
| | - Raquel Pérez-Palacios
- Regenerative Medicine Program, Instituto Aragonés de Ciencias de la Salud , Zaragoza , Spain
| | - María Climent
- Departamento de Anatomía, Embriología y Genética Animal, Facultad de Veterinaria, Universidad de Zaragoza , Zaragoza , Spain
| | - Diana Guallar
- Regenerative Medicine Program, Instituto Aragonés de Ciencias de la Salud , Zaragoza , Spain
| | - Pedro Muniesa
- Departamento de Anatomía, Embriología y Genética Animal, Facultad de Veterinaria, Universidad de Zaragoza , Zaragoza , Spain
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42
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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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43
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Villarreal LP, Witzany G. The DNA Habitat and its RNA Inhabitants: At the Dawn of RNA Sociology. GENOMICS INSIGHTS 2013; 6:1-12. [PMID: 26217106 PMCID: PMC4510605 DOI: 10.4137/gei.s11490] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Most molecular biological concepts derive from physical chemical assumptions about the genetic code that are basically more than 40 years old. Additionally, systems biology, another quantitative approach, investigates the sum of interrelations to obtain a more holistic picture of nucleotide sequence order. Recent empirical data on genetic code compositions and rearrangements by mobile genetic elements and noncoding RNAs, together with results of virus research and their role in evolution, does not really fit into these concepts and compel a reexamination. In this review, we try to find an alternate hypothesis. It seems plausible now that if we look at the abundance of regulatory RNAs and persistent viruses in host genomes, we will find more and more evidence that the key players that edit the genetic codes of host genomes are consortia of RNA agents and viruses that drive evolutionary novelty and regulation of cellular processes in all steps of development. This agent-based approach may lead to a qualitative RNA sociology that investigates and identifies relevant behavioral motifs of cooperative RNA consortia. In addition to molecular biological perspectives, this may lead to a better understanding of genetic code evolution and dynamics.
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Affiliation(s)
- Luis P Villarreal
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, USA
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Long interspersed element-1 is differentially regulated by food-borne carcinogens via the aryl hydrocarbon receptor. Oncogene 2012. [PMID: 23208499 PMCID: PMC3795476 DOI: 10.1038/onc.2012.516] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A single human cell contains more than 5.0 × 10(5) copies of long interspersed element-1 (L1), 80-100 of which are competent for retrotransposition (L1-RTP). Recent observations have revealed the presence of de novo L1 insertions in various tumors, but little is known about its mechanism. Here, we found that 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), food-borne carcinogens that are present in broiled meats, induced L1-RTP. This induction was dependent on a cellular cascade comprising the aryl hydrocarbon receptor (AhR), a mitogen-activated protein kinase, and CCAAT/enhancer-binding protein β. Notably, these compounds exhibited differential induction of L1-RTP. MeIQx-induced L1-RTP was dependent on AhR nuclear translocator 1 (ARNT1), a counterpart of AhR required for gene expression in response to environmental pollutants. By contrast, PhIP-induced L1-RTP did not require ARNT1 but was dependent on estrogen receptor α (ERα) and AhR repressor. In vivo studies using transgenic mice harboring the human L1 gene indicated that PhIP-induced L1-RTP was reproducibly detected in the mammary gland, which is a target organ of PhIP-induced carcinoma. Moreover, picomolar levels of each compound induced L1-RTP, which is comparable to the PhIP concentration detected in human breast milk. Data suggest that somatic cells possess machineries that induce L1-RTP in response to the carcinogenic compounds. Together with data showing that micromolar levels of heterocyclic amines (HCAs) were non-genotoxic, our observations indicate that L1-RTP by environmental compounds is a novel type of genomic instability, further suggesting that analysis of L1-RTP by HCAs is a novel approach to clarification of modes of carcinogenesis.
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Ishizaka Y, Okudaira N, Tamura M, Iijima K, Shimura M, Goto M, Okamura T. Modes of retrotransposition of long interspersed element-1 by environmental factors. Front Microbiol 2012; 3:191. [PMID: 22666219 PMCID: PMC3364524 DOI: 10.3389/fmicb.2012.00191] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 05/10/2012] [Indexed: 11/13/2022] Open
Abstract
Approximately 42% of the human genome is composed of endogenous retroelements, and the major retroelement component, long interspersed element-1 (L1), comprises ∼17% of the total genome. A single human cell has more than 5 × 10(5) copies of L1, 80∼100 copies of which are competent for retrotransposition (RTP). Notably, L1 can induce RTP of other retroelements, such as Alu and SVA, and is believed to function as a driving force of evolution. Although L1-RTP during early embryogenesis has been highlighted in the literature, recent observations revealed that L1-RTP also occurs in somatic cells. However, little is known about how environmental factors induce L1-RTP. Here, we summarize our current understanding of the mechanism of L1-RTP in somatic cells. We have focused on the mode of L1-RTP that is dependent on the basic helix-loop-helix/per-arnt-sim (bHLH/PAS) family of transcription factors. Along with the proposed function of bHLH/PAS proteins in environmental adaptation, we discuss the functional linking of L1-RTP and bHLH/PAS proteins for environmental adaptation and evolution.
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Affiliation(s)
- Yukihito Ishizaka
- Department of Intractable Diseases, National Center for Global Health and Medicine Tokyo, Japan
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