1
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Vukic M, Chouaref J, Della Chiara V, Dogan S, Ratner F, Hogenboom JZM, Epp TA, Chawengsaksophak K, Vonk KKD, Breukel C, Ariyurek Y, San Leon Granado D, Kloet SL, Daxinger L. CDCA7-associated global aberrant DNA hypomethylation translates to localized, tissue-specific transcriptional responses. SCIENCE ADVANCES 2024; 10:eadk3384. [PMID: 38335290 PMCID: PMC10857554 DOI: 10.1126/sciadv.adk3384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 01/09/2024] [Indexed: 02/12/2024]
Abstract
Disruption of cell division cycle associated 7 (CDCA7) has been linked to aberrant DNA hypomethylation, but the impact of DNA methylation loss on transcription has not been investigated. Here, we show that CDCA7 is critical for maintaining global DNA methylation levels across multiple tissues in vivo. A pathogenic Cdca7 missense variant leads to the formation of large, aberrantly hypomethylated domains overlapping with the B genomic compartment but without affecting the deposition of H3K9 trimethylation (H3K9me3). CDCA7-associated aberrant DNA hypomethylation translated to localized, tissue-specific transcriptional dysregulation that affected large gene clusters. In the brain, we identify CDCA7 as a transcriptional repressor and epigenetic regulator of clustered protocadherin isoform choice. Increased protocadherin isoform expression frequency is accompanied by DNA methylation loss, gain of H3K4 trimethylation (H3K4me3), and increased binding of the transcriptional regulator CCCTC-binding factor (CTCF). Overall, our in vivo work identifies a key role for CDCA7 in safeguarding tissue-specific expression of gene clusters via the DNA methylation pathway.
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Affiliation(s)
- Maja Vukic
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | - Jihed Chouaref
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | | | - Serkan Dogan
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | - Fallon Ratner
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | | | - Trevor A. Epp
- Laboratory of Cell Differentiation, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
- CZ-OPENSCREEN, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Kallayanee Chawengsaksophak
- Laboratory of Cell Differentiation, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Kelly K. D. Vonk
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | - Cor Breukel
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | - Yavuz Ariyurek
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
- Leiden Genome Technology Center, Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | | | - Susan L. Kloet
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
- Leiden Genome Technology Center, Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
| | - Lucia Daxinger
- Department of Human Genetics, Leiden University Medical Center, Leiden, Netherlands
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2
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Derakhshan M, Kessler NJ, Hellenthal G, Silver MJ. Metastable epialleles in humans. Trends Genet 2024; 40:52-68. [PMID: 38000919 DOI: 10.1016/j.tig.2023.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 09/20/2023] [Accepted: 09/21/2023] [Indexed: 11/26/2023]
Abstract
First identified in isogenic mice, metastable epialleles (MEs) are loci where the extent of DNA methylation (DNAm) is variable between individuals but correlates across tissues derived from different germ layers within a given individual. This property, termed systemic interindividual variation (SIV), is attributed to stochastic methylation establishment before germ layer differentiation. Evidence suggests that some putative human MEs are sensitive to environmental exposures in early development. In this review we introduce key concepts pertaining to human MEs, describe methods used to identify MEs in humans, and review their genomic features. We also highlight studies linking DNAm at putative human MEs to early environmental exposures and postnatal (including disease) phenotypes.
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Affiliation(s)
- Maria Derakhshan
- London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Noah J Kessler
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | | | - Matt J Silver
- London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK; Medical Research Council (MRC) Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, Banjul, The Gambia.
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3
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Gerdes P, Chan D, Lundberg M, Sanchez-Luque FJ, Bodea GO, Ewing AD, Faulkner GJ, Richardson SR. Locus-resolution analysis of L1 regulation and retrotransposition potential in mouse embryonic development. Genome Res 2023; 33:1465-1481. [PMID: 37798118 PMCID: PMC10620060 DOI: 10.1101/gr.278003.123] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 08/21/2023] [Indexed: 10/07/2023]
Abstract
Mice harbor ∼2800 intact copies of the retrotransposon Long Interspersed Element 1 (L1). The in vivo retrotransposition capacity of an L1 copy is defined by both its sequence integrity and epigenetic status, including DNA methylation of the monomeric units constituting young mouse L1 promoters. Locus-specific L1 methylation dynamics during development may therefore elucidate and explain spatiotemporal niches of endogenous retrotransposition but remain unresolved. Here, we interrogate the retrotransposition efficiency and epigenetic fate of source (donor) L1s, identified as mobile in vivo. We show that promoter monomer loss consistently attenuates the relative retrotransposition potential of their offspring (daughter) L1 insertions. We also observe that most donor/daughter L1 pairs are efficiently methylated upon differentiation in vivo and in vitro. We use Oxford Nanopore Technologies (ONT) long-read sequencing to resolve L1 methylation genome-wide and at individual L1 loci, revealing a distinctive "smile" pattern in methylation levels across the L1 promoter region. Using Pacific Biosciences (PacBio) SMRT sequencing of L1 5' RACE products, we then examine DNA methylation dynamics at the mouse L1 promoter in parallel with transcription start site (TSS) distribution at locus-specific resolution. Together, our results offer a novel perspective on the interplay between epigenetic repression, L1 evolution, and genome stability.
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Affiliation(s)
- Patricia Gerdes
- Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, Queensland 4102, Australia
| | - Dorothy Chan
- Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, Queensland 4102, Australia
| | - Mischa Lundberg
- Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, Queensland 4102, Australia
- The University of Queensland Diamantina Institute, The University of Queensland, Woolloongabba, Queensland 4102, Australia
- Translational Bioinformatics, Commonwealth Scientific and Industrial Research Organisation, Sydney, New South Wales 2113, Australia
| | - Francisco J Sanchez-Luque
- Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, Queensland 4102, Australia
- GENYO. Centre for Genomics and Oncological Research (Pfizer-University of Granada-Andalusian Regional Government), PTS Granada, 18016, Spain
- MRC Human Genetics Unit, Institute of Genetics and Cancer (IGC), University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
| | - Gabriela O Bodea
- Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, Queensland 4102, Australia
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Adam D Ewing
- Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, Queensland 4102, Australia
| | - Geoffrey J Faulkner
- Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, Queensland 4102, Australia;
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Sandra R Richardson
- Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, Queensland 4102, Australia;
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4
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Crane-Smith Z, De Castro SCP, Nikolopoulou E, Wolujewicz P, Smedley D, Lei Y, Mather E, Santos C, Hopkinson M, Pitsillides AA, Finnell RH, Ross ME, Copp AJ, Greene NDE. A non-coding insertional mutation of Grhl2 causes gene over-expression and multiple structural anomalies including cleft palate, spina bifida and encephalocele. Hum Mol Genet 2023; 32:2681-2692. [PMID: 37364051 PMCID: PMC10460492 DOI: 10.1093/hmg/ddad094] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/19/2023] [Accepted: 06/15/2023] [Indexed: 06/28/2023] Open
Abstract
Orofacial clefts, including cleft lip and palate (CL/P) and neural tube defects (NTDs) are among the most common congenital anomalies, but knowledge of the genetic basis of these conditions remains incomplete. The extent to which genetic risk factors are shared between CL/P, NTDs and related anomalies is also unclear. While identification of causative genes has largely focused on coding and loss of function mutations, it is hypothesized that regulatory mutations account for a portion of the unidentified heritability. We found that excess expression of Grainyhead-like 2 (Grhl2) causes not only spinal NTDs in Axial defects (Axd) mice but also multiple additional defects affecting the cranial region. These include orofacial clefts comprising midline cleft lip and palate and abnormalities of the craniofacial bones and frontal and/or basal encephalocele, in which brain tissue herniates through the cranium or into the nasal cavity. To investigate the causative mutation in the Grhl2Axd strain, whole genome sequencing identified an approximately 4 kb LTR retrotransposon insertion that disrupts the non-coding regulatory region, lying approximately 300 base pairs upstream of the 5' UTR. This insertion also lies within a predicted long non-coding RNA, oriented on the reverse strand, which like Grhl2 is over-expressed in Axd (Grhl2Axd) homozygous mutant embryos. Initial analysis of the GRHL2 upstream region in individuals with NTDs or cleft palate revealed rare or novel variants in a small number of cases. We hypothesize that mutations affecting the regulation of GRHL2 may contribute to craniofacial anomalies and NTDs in humans.
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Affiliation(s)
- Zoe Crane-Smith
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Sandra C P De Castro
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Evanthia Nikolopoulou
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Paul Wolujewicz
- Center for Neurogenetics, Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York 10065, USA
| | - Damian Smedley
- William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
| | - Yunping Lei
- Center for Precision Environmental Health, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Emma Mather
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Chloe Santos
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Mark Hopkinson
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London NW1 0TU, UK
| | - Andrew A Pitsillides
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London NW1 0TU, UK
| | | | - Richard H Finnell
- Center for Precision Environmental Health, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - M Elisabeth Ross
- Center for Neurogenetics, Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York 10065, USA
| | - Andrew J Copp
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Nicholas D E Greene
- Developmental Biology and Cancer Department, Great Ormond Street Institute of Child Health, University College London, London WC1N 1EH, UK
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5
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Gunasekara CJ, MacKay H, Scott CA, Li S, Laritsky E, Baker MS, Grimm SL, Jun G, Li Y, Chen R, Wiemels JL, Coarfa C, Waterland RA. Systemic interindividual epigenetic variation in humans is associated with transposable elements and under strong genetic control. Genome Biol 2023; 24:2. [PMID: 36631879 PMCID: PMC9835319 DOI: 10.1186/s13059-022-02827-3] [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: 08/04/2022] [Accepted: 12/01/2022] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Genetic variants can modulate phenotypic outcomes via epigenetic intermediates, for example at methylation quantitative trait loci (mQTL). We present the first large-scale assessment of mQTL at human genomic regions selected for interindividual variation in CpG methylation, which we call correlated regions of systemic interindividual variation (CoRSIVs). These can be assayed in blood DNA and do not reflect interindividual variation in cellular composition. RESULTS We use target-capture bisulfite sequencing to assess DNA methylation at 4086 CoRSIVs in multiple tissues from each of 188 donors in the NIH Gene-Tissue Expression (GTEx) program. At CoRSIVs, DNA methylation in peripheral blood correlates with methylation and gene expression in internal organs. We also discover unprecedented mQTL at these regions. Genetic influences on CoRSIV methylation are extremely strong (median R2=0.76), cumulatively comprising over 70-fold more human mQTL than detected in the most powerful previous study. Moreover, mQTL beta coefficients at CoRSIVs are highly skewed (i.e., the major allele predicts higher methylation). Both surprising findings are independently validated in a cohort of 47 non-GTEx individuals. Genomic regions flanking CoRSIVs show long-range enrichments for LINE-1 and LTR transposable elements; the skewed beta coefficients may therefore reflect evolutionary selection of genetic variants that promote their methylation and silencing. Analyses of GWAS summary statistics show that mQTL polymorphisms at CoRSIVs are associated with metabolic and other classes of disease. CONCLUSIONS A focus on systemic interindividual epigenetic variants, clearly enhanced in mQTL content, should likewise benefit studies attempting to link human epigenetic variation to the risk of disease.
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Affiliation(s)
- Chathura J. Gunasekara
- grid.508989.50000 0004 6410 7501USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX USA
| | - Harry MacKay
- grid.508989.50000 0004 6410 7501USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX USA
| | - C. Anthony Scott
- grid.508989.50000 0004 6410 7501USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX USA
| | - Shaobo Li
- grid.42505.360000 0001 2156 6853Keck School of Medicine, University of Southern California, Los Angeles, CA USA
| | - Eleonora Laritsky
- grid.508989.50000 0004 6410 7501USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX USA
| | - Maria S. Baker
- grid.508989.50000 0004 6410 7501USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX USA
| | - Sandra L. Grimm
- grid.39382.330000 0001 2160 926XDepartment of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX USA
| | - Goo Jun
- grid.267308.80000 0000 9206 2401Human Genetics Center, University of Texas Health Science Center at Houston, Houston, TX USA
| | - Yumei Li
- grid.39382.330000 0001 2160 926XDepartment of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX USA
| | - Rui Chen
- grid.39382.330000 0001 2160 926XDepartment of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX USA
| | - Joseph L. Wiemels
- grid.42505.360000 0001 2156 6853Keck School of Medicine, University of Southern California, Los Angeles, CA USA
| | - Cristian Coarfa
- grid.39382.330000 0001 2160 926XDepartment of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX USA ,grid.39382.330000 0001 2160 926XDan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX USA
| | - Robert A. Waterland
- grid.508989.50000 0004 6410 7501USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX USA ,grid.39382.330000 0001 2160 926XDepartment of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX USA
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6
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Derakhshan M, Kessler NJ, Ishida M, Demetriou C, Brucato N, Moore G, Fall CHD, Chandak GR, Ricaut FX, Prentice A, Hellenthal G, Silver M. Tissue- and ethnicity-independent hypervariable DNA methylation states show evidence of establishment in the early human embryo. Nucleic Acids Res 2022; 50:6735-6752. [PMID: 35713545 PMCID: PMC9749461 DOI: 10.1093/nar/gkac503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 05/06/2022] [Accepted: 05/27/2022] [Indexed: 12/24/2022] Open
Abstract
We analysed DNA methylation data from 30 datasets comprising 3474 individuals, 19 tissues and 8 ethnicities at CpGs covered by the Illumina450K array. We identified 4143 hypervariable CpGs ('hvCpGs') with methylation in the top 5% most variable sites across multiple tissues and ethnicities. hvCpG methylation was influenced but not determined by genetic variation, and was not linked to probe reliability, epigenetic drift, age, sex or cell heterogeneity effects. hvCpG methylation tended to covary across tissues derived from different germ-layers and hvCpGs were enriched for proximity to ERV1 and ERVK retrovirus elements. hvCpGs were also enriched for loci previously associated with periconceptional environment, parent-of-origin-specific methylation, and distinctive methylation signatures in monozygotic twins. Together, these properties position hvCpGs as strong candidates for studying how stochastic and/or environmentally influenced DNA methylation states which are established in the early embryo and maintained stably thereafter can influence life-long health and disease.
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Affiliation(s)
| | - Noah J Kessler
- Department of Genetics, University of Cambridge,
Cambridge CB2 3EH, UK
| | - Miho Ishida
- UCL Great Ormond Street Institute of Child Health, UK
| | | | - Nicolas Brucato
- Laboratoire Évolution and Diversité Biologique (EDB UMR 5174), Université
de Toulouse Midi-Pyrénées, CNRS, IRD, UPS,Toulouse, France
| | | | - Caroline H D Fall
- MRC Lifecourse Epidemiology Unit, University of Southampton,
Southampton, UK
| | - Giriraj R Chandak
- Genomic Research on Complex Diseases (GRC Group), CSIR-Centre for Cellular
and Molecular Biology,Hyderabad, India
| | - Francois-Xavier Ricaut
- Laboratoire Évolution and Diversité Biologique (EDB UMR 5174), Université
de Toulouse Midi-Pyrénées, CNRS, IRD, UPS,Toulouse, France
| | - Andrew M Prentice
- Medical Research Council Unit The Gambia at the London School of Hygiene
and Tropical Medicine, The Gambia
| | - Garrett Hellenthal
- UCL Genetics Institute, University College London,
Gower Street, London WC1E 6BT, UK
| | - Matt J Silver
- London School of Hygiene and Tropical Medicine, UK
- Medical Research Council Unit The Gambia at the London School of Hygiene
and Tropical Medicine, The Gambia
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7
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Di Giorgio E, Xodo LE. Endogenous Retroviruses (ERVs): Does RLR (RIG-I-Like Receptors)-MAVS Pathway Directly Control Senescence and Aging as a Consequence of ERV De-Repression? Front Immunol 2022; 13:917998. [PMID: 35757716 PMCID: PMC9218063 DOI: 10.3389/fimmu.2022.917998] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
Bi-directional transcription of Human Endogenous Retroviruses (hERVs) is a common feature of autoimmunity, neurodegeneration and cancer. Higher rates of cancer incidence, neurodegeneration and autoimmunity but a lower prevalence of autoimmune diseases characterize elderly people. Although the re-expression of hERVs is commonly observed in different cellular models of senescence as a result of the loss of their epigenetic transcriptional silencing, the hERVs modulation during aging is more complex, with a peak of activation in the sixties and a decline in the nineties. What is clearly accepted, instead, is the impact of the re-activation of dormant hERV on the maintenance of stemness and tissue self-renewing properties. An innate cellular immunity system, based on the RLR-MAVS circuit, controls the degradation of dsRNAs arising from the transcription of hERV elements, similarly to what happens for the accumulation of cytoplasmic DNA leading to the activation of cGAS/STING pathway. While agonists and inhibitors of the cGAS-STING pathway are considered promising immunomodulatory molecules, the effect of the RLR-MAVS pathway on innate immunity is still largely based on correlations and not on causality. Here we review the most recent evidence regarding the activation of MDA5-RIG1-MAVS pathway as a result of hERV de-repression during aging, immunosenescence, cancer and autoimmunity. We will also deal with the epigenetic mechanisms controlling hERV repression and with the strategies that can be adopted to modulate hERV expression in a therapeutic perspective. Finally, we will discuss if the RLR-MAVS signalling pathway actively modulates physiological and pathological conditions or if it is passively activated by them.
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Affiliation(s)
- Eros Di Giorgio
- Laboratory of Biochemistry, Department of Medicine, University of Udine, Udine, Italy
| | - Luigi E Xodo
- Laboratory of Biochemistry, Department of Medicine, University of Udine, Udine, Italy
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8
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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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9
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Buttler CA, Chuong EB. Emerging roles for endogenous retroviruses in immune epigenetic regulation. Immunol Rev 2022; 305:165-178. [PMID: 34816452 PMCID: PMC8766910 DOI: 10.1111/imr.13042] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/21/2021] [Accepted: 11/12/2021] [Indexed: 01/03/2023]
Abstract
In recent years, there has been significant progress toward understanding the transcriptional networks underlying mammalian immune responses, fueled by advances in regulatory genomic technologies. Epigenomic studies profiling immune cells have generated detailed genome-wide maps of regulatory elements that will be key to deciphering the regulatory networks underlying cellular immune responses and autoimmune disorders. Unbiased analyses of these genomic maps have uncovered endogenous retroviruses as an unexpected ally in the regulation of human immune systems. Despite their parasitic origins, studies are finding an increasing number of examples of retroviral sequences having been co-opted for beneficial immune function and regulation by the host cell. Here, we review how endogenous retroviruses have given rise to numerous regulatory elements that shape the epigenetic landscape of host immune responses. We will discuss the implications of these elements on the function, dysfunction, and evolution of innate immunity.
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10
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Costello KR, Leung A, Trac C, Lee M, Basam M, Pospisilik JA, Schones DE. Sequence features of retrotransposons allow for epigenetic variability. eLife 2021; 10:71104. [PMID: 34668484 PMCID: PMC8555987 DOI: 10.7554/elife.71104] [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: 06/09/2021] [Accepted: 10/20/2021] [Indexed: 12/12/2022] Open
Abstract
Transposable elements (TEs) are mobile genetic elements that make up a large fraction of mammalian genomes. While select TEs have been co-opted in host genomes to have function, the majority of these elements are epigenetically silenced by DNA methylation in somatic cells. However, some TEs in mice, including the Intracisternal A-particle (IAP) subfamily of retrotransposons, have been shown to display interindividual variation in DNA methylation. Recent work has revealed that IAP sequence differences and strain-specific KRAB zinc finger proteins (KZFPs) may influence the methylation state of these IAPs. However, the mechanisms underlying the establishment and maintenance of interindividual variability in DNA methylation still remain unclear. Here, we report that sequence content and genomic context influence the likelihood that IAPs become variably methylated. IAPs that differ from consensus IAP sequences have altered KZFP recruitment that can lead to decreased KAP1 recruitment when in proximity of constitutively expressed genes. These variably methylated loci have a high CpG density, similar to CpG islands, and can be bound by ZF-CxxC proteins, providing a potential mechanism to maintain this permissive chromatin environment and protect from DNA methylation. These observations indicate that variably methylated IAPs escape silencing through both attenuation of KZFP binding and recognition by ZF-CxxC proteins to maintain a hypomethylated state.
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Affiliation(s)
- Kevin R Costello
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, Duarte, United States.,Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, United States
| | - Amy Leung
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, Duarte, United States
| | - Candi Trac
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, Duarte, United States
| | - Michael Lee
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, Duarte, United States.,Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, United States
| | - Mudaser Basam
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, Duarte, United States
| | | | - Dustin E Schones
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, Duarte, United States.,Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, United States
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11
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Bioinformatics and Machine Learning Approaches to Understand the Regulation of Mobile Genetic Elements. BIOLOGY 2021; 10:biology10090896. [PMID: 34571773 PMCID: PMC8465862 DOI: 10.3390/biology10090896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/06/2021] [Accepted: 09/07/2021] [Indexed: 11/22/2022]
Abstract
Simple Summary Transposable elements (TEs) are DNA sequences that are, or were, able to move (transpose) within the genome of a single cell. They were first discovered by Barbara McClintock while working on maize, and they make up a large fraction of the genome. Transpositions can result in mutations and they can alter the genome size. Cells regulate the activity of TEs using a variety of mechanisms, such as chemical modifications of DNA and small RNAs. Machine learning (ML) is an interdisciplinary subject that studies computer algorithms that can improve through experience and by the use of data. ML has been successfully applied to a variety of problems in bioinformatics and has exhibited favorable precision and speed. Here, we provide a systematic and guided review on the ML and bioinformatic methods and tools that are used for the analysis of the regulation of TEs. Abstract Transposable elements (TEs, or mobile genetic elements, MGEs) are ubiquitous genetic elements that make up a substantial proportion of the genome of many species. The recent growing interest in understanding the evolution and function of TEs has revealed that TEs play a dual role in genome evolution, development, disease, and drug resistance. Cells regulate TE expression against uncontrolled activity that can lead to developmental defects and disease, using multiple strategies, such as DNA chemical modification, small RNA (sRNA) silencing, chromatin modification, as well as sequence-specific repressors. Advancements in bioinformatics and machine learning approaches are increasingly contributing to the analysis of the regulation mechanisms. A plethora of tools and machine learning approaches have been developed for prediction, annotation, and expression profiling of sRNAs, for methylation analysis of TEs, as well as for genome-wide methylation analysis through bisulfite sequencing data. In this review, we provide a guided overview of the bioinformatic and machine learning state of the art of fields closely associated with TE regulation and function.
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Bertozzi TM, Becker JL, Blake GET, Bansal A, Nguyen DK, Fernandez-Twinn DS, Ozanne SE, Bartolomei MS, Simmons RA, Watson ED, Ferguson-Smith AC. Variably methylated retrotransposons are refractory to a range of environmental perturbations. Nat Genet 2021; 53:1233-1242. [PMID: 34326545 PMCID: PMC7611517 DOI: 10.1038/s41588-021-00898-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 06/18/2021] [Indexed: 12/27/2022]
Abstract
The agouti viable yellow (Avy) allele is an insertional mutation in the mouse genome caused by a variably methylated intracisternal A particle (VM-IAP) retrotransposon. Avy expressivity is sensitive to a range of early-life chemical exposures and nutritional interventions, suggesting that environmental perturbations can have long-lasting effects on the methylome. However, the extent to which VM-IAP elements are environmentally labile with phenotypic implications is unknown. Using a recently identified repertoire of VM-IAPs, we assessed the epigenetic effects of different environmental contexts. A longitudinal aging analysis indicated that VM-IAPs are stable across the murine lifespan, with only small increases in DNA methylation detected for a subset of loci. No significant effects were observed after maternal exposure to the endocrine disruptor bisphenol A, an obesogenic diet or methyl donor supplementation. A genetic mouse model of abnormal folate metabolism exhibited shifted VM-IAP methylation levels and altered VM-IAP-associated gene expression, yet these effects are likely largely driven by differential targeting by polymorphic KRAB zinc finger proteins. We conclude that epigenetic variability at retrotransposons is not predictive of environmental susceptibility.
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Affiliation(s)
| | | | - Georgina E T Blake
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
- Centre for Trophoblast Research, University of Cambridge, Cambridge, UK
| | - Amita Bansal
- Center for Research on Reproduction and Women's Health, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Australian National University Medical School, John Curtin School of Medical Research, College of Health and Medicine, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Duy K Nguyen
- Department of Cell and Developmental Biology, Perelman School of Medicine, Epigenetics Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Denise S Fernandez-Twinn
- University of Cambridge Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust Medical Research Council Institute of Metabolic Science, Cambridge, UK
| | - Susan E Ozanne
- University of Cambridge Metabolic Research Laboratories and Medical Research Council Metabolic Diseases Unit, Wellcome Trust Medical Research Council Institute of Metabolic Science, Cambridge, UK
| | - Marisa S Bartolomei
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Cell and Developmental Biology, Perelman School of Medicine, Epigenetics Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Rebecca A Simmons
- Center for Research on Reproduction and Women's Health, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Center of Excellence in Environmental Toxicology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Division of Neonatology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Erica D Watson
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
- Centre for Trophoblast Research, University of Cambridge, Cambridge, UK
| | - Anne C Ferguson-Smith
- Department of Genetics, University of Cambridge, Cambridge, UK.
- Centre for Trophoblast Research, University of Cambridge, Cambridge, UK.
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Bertozzi TM, Takahashi N, Hanin G, Kazachenka A, Ferguson-Smith AC. A spontaneous genetically induced epiallele at a retrotransposon shapes host genome function. eLife 2021; 10:e65233. [PMID: 33755012 PMCID: PMC8084528 DOI: 10.7554/elife.65233] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 03/22/2021] [Indexed: 12/14/2022] Open
Abstract
Intracisternal A-particles (IAPs) are endogenous retroviruses (ERVs) responsible for most insertional mutations in the mouse. Full-length IAPs harbour genes flanked by long terminal repeats (LTRs). Here, we identify a solo LTR IAP variant (Iap5-1solo) recently formed in the inbred C57BL/6J mouse strain. In contrast to the C57BL/6J full-length IAP at this locus (Iap5-1full), Iap5-1solo lacks DNA methylation and H3K9 trimethylation. The distinct DNA methylation levels between the two alleles are established during preimplantation development, likely due to loss of KRAB zinc finger protein binding at the Iap5-1solo variant. Iap5-1solo methylation increases and becomes more variable in a hybrid genetic background yet is unresponsive to maternal dietary methyl supplementation. Differential epigenetic modification of the two variants is associated with metabolic differences and tissue-specific changes in adjacent gene expression. Our characterisation of Iap5-1 as a genetically induced epiallele with functional consequences establishes a new model to study transposable element repression and host-element co-evolution.
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Affiliation(s)
- Tessa M Bertozzi
- Department of Genetics, University of CambridgeCambridgeUnited Kingdom
| | - Nozomi Takahashi
- Department of Genetics, University of CambridgeCambridgeUnited Kingdom
| | - Geula Hanin
- Department of Genetics, University of CambridgeCambridgeUnited Kingdom
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