1
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Maggioni E, Colli C, Bizzotto C, Finaurini S, Fagnani C, Medda E, Bonivento C, Rosi E, Mauri M, Nobile M, Brambilla P. Investigating the impact of L1 retrotransposons on behavior: A pilot study on young twins. Schizophr Res 2024; 271:353-354. [PMID: 39098302 DOI: 10.1016/j.schres.2024.07.052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 07/09/2024] [Accepted: 07/26/2024] [Indexed: 08/06/2024]
Affiliation(s)
- Eleonora Maggioni
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Chiara Colli
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Cristina Bizzotto
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Sara Finaurini
- Neuroscience Area, SISSA, International School for Advanced Studies, Trieste, Italy
| | - Corrado Fagnani
- Italian Twin Registry, Centre for Behavioural Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
| | - Emanuela Medda
- Italian Twin Registry, Centre for Behavioural Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
| | | | - Eleonora Rosi
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini (LC), Italy
| | - Maddalena Mauri
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini (LC), Italy
| | - Maria Nobile
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini (LC), Italy
| | - Paolo Brambilla
- Department of Neurosciences and Mental Health, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
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2
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McClellan JM, Zoghbi AW, Buxbaum JD, Cappi C, Crowley JJ, Flint J, Grice DE, Gulsuner S, Iyegbe C, Jain S, Kuo PH, Lattig MC, Passos-Bueno MR, Purushottam M, Stein DJ, Sunshine AB, Susser ES, Walsh CA, Wootton O, King MC. An evolutionary perspective on complex neuropsychiatric disease. Neuron 2024; 112:7-24. [PMID: 38016473 PMCID: PMC10842497 DOI: 10.1016/j.neuron.2023.10.037] [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: 08/02/2022] [Revised: 08/09/2023] [Accepted: 10/26/2023] [Indexed: 11/30/2023]
Abstract
The forces of evolution-mutation, selection, migration, and genetic drift-shape the genetic architecture of human traits, including the genetic architecture of complex neuropsychiatric illnesses. Studying these illnesses in populations that are diverse in genetic ancestry, historical demography, and cultural history can reveal how evolutionary forces have guided adaptation over time and place. A fundamental truth of shared human biology is that an allele responsible for a disease in anyone, anywhere, reveals a gene critical to the normal biology underlying that condition in everyone, everywhere. Understanding the genetic causes of neuropsychiatric disease in the widest possible range of human populations thus yields the greatest possible range of insight into genes critical to human brain development. In this perspective, we explore some of the relationships between genes, adaptation, and history that can be illuminated by an evolutionary perspective on studies of complex neuropsychiatric disease in diverse populations.
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Affiliation(s)
- Jon M McClellan
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98195, USA
| | - Anthony W Zoghbi
- Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX 77030, USA
| | - Joseph D Buxbaum
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Carolina Cappi
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - James J Crowley
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jonathan Flint
- Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Dorothy E Grice
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Suleyman Gulsuner
- Department of Medicine and Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Conrad Iyegbe
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Sanjeev Jain
- Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bengaluru 560029, India
| | - Po-Hsiu Kuo
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei 100, Taiwan
| | | | | | - Meera Purushottam
- Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bengaluru 560029, India
| | - Dan J Stein
- SAMRC Unit on Risk and Resilience in Mental Disorders, Department of Psychiatry, University of Cape Town, Cape Town, South Africa
| | - Anna B Sunshine
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98195, USA; Department of Medicine and Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Ezra S Susser
- Department of Epidemiology, Mailman School of Public Health, and New York State Psychiatric Institute, Columbia University, New York, NY 10032, USA
| | - Christopher A Walsh
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Division of Genetics and Genomics and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA 02115, USA; Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Olivia Wootton
- SAMRC Unit on Risk and Resilience in Mental Disorders, Department of Psychiatry, University of Cape Town, Cape Town, South Africa
| | - Mary-Claire King
- Department of Medicine and Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.
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3
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Tam PLF, Leung D. The Molecular Impacts of Retrotransposons in Development and Diseases. Int J Mol Sci 2023; 24:16418. [PMID: 38003607 PMCID: PMC10671454 DOI: 10.3390/ijms242216418] [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: 10/07/2023] [Revised: 11/11/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Retrotransposons are invasive genetic elements that constitute substantial portions of mammalian genomes. They have the potential to influence nearby gene expression through their cis-regulatory sequences, reverse transcription machinery, and the ability to mold higher-order chromatin structures. Due to their multifaceted functions, it is crucial for host fitness to maintain strict regulation of these parasitic sequences to ensure proper growth and development. This review explores how subsets of retrotransposons have undergone evolutionary exaptation to enhance the complexity of mammalian genomes. It also highlights the significance of regulating these elements, drawing on recent studies conducted in human and murine systems.
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Affiliation(s)
- Phoebe Lut Fei Tam
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China;
| | - Danny Leung
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China;
- Center for Epigenomics Research, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China
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4
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Devine SE. Emerging Opportunities to Study Mobile Element Insertions and Their Source Elements in an Expanding Universe of Sequenced Human Genomes. Genes (Basel) 2023; 14:1923. [PMID: 37895272 PMCID: PMC10606232 DOI: 10.3390/genes14101923] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 09/29/2023] [Accepted: 09/30/2023] [Indexed: 10/29/2023] Open
Abstract
Three mobile element classes, namely Alu, LINE-1 (L1), and SVA elements, remain actively mobile in human genomes and continue to produce new mobile element insertions (MEIs). Historically, MEIs have been discovered and studied using several methods, including: (1) Southern blots, (2) PCR (including PCR display), and (3) the detection of MEI copies from young subfamilies. We are now entering a new phase of MEI discovery where these methods are being replaced by whole genome sequencing and bioinformatics analysis to discover novel MEIs. We expect that the universe of sequenced human genomes will continue to expand rapidly over the next several years, both with short-read and long-read technologies. These resources will provide unprecedented opportunities to discover MEIs and study their impact on human traits and diseases. They also will allow the MEI community to discover and study the source elements that produce these new MEIs, which will facilitate our ability to study source element regulation in various tissue contexts and disease states. This, in turn, will allow us to better understand MEI mutagenesis in humans and the impact of this mutagenesis on human biology.
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Affiliation(s)
- Scott E Devine
- Institute for Genome Sciences, Department of Medicine, and Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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5
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Gooding DC, Auger AP. Polygenic risk scores cannot make their mark on psychiatry without considering epigenetics. Behav Brain Sci 2023; 46:e216. [PMID: 37695011 DOI: 10.1017/s0140525x22002412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
We generally agree with Burt's thesis. However, we note that the author did not discuss epigenetics, the study of how the environment can alter gene structure and function. Given epigenetic mechanisms, the utility of polygenic risk scores (PRS) is limited in studies of development and mental illness. Finally, in this commentary we expand upon the risks of reliance upon PRSs.
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Affiliation(s)
- Diane C Gooding
- Department of Psychology, University of Wisconsin-Madison, Madison, WI, USA ; https://drdianecgooding.com ; https://augerlab.labs.wisc.edu
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI, USA
| | - Anthony P Auger
- Department of Psychology, University of Wisconsin-Madison, Madison, WI, USA ; https://drdianecgooding.com ; https://augerlab.labs.wisc.edu
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, USA
- Department of Endocrinology and Reproductive, University of Wisconsin-Madison, Madison, WI, USA
- Physiology, and Department of Cellular and Molecular Pharmacology, University of Wisconsin-Madison, Madison, WI, USA
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6
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Gebrie A. Transposable elements as essential elements in the control of gene expression. Mob DNA 2023; 14:9. [PMID: 37596675 PMCID: PMC10439571 DOI: 10.1186/s13100-023-00297-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 08/08/2023] [Indexed: 08/20/2023] Open
Abstract
Interspersed repetitions called transposable elements (TEs), commonly referred to as mobile elements, make up a significant portion of the genomes of higher animals. TEs contribute in controlling the expression of genes locally and even far away at the transcriptional and post-transcriptional levels, which is one of their significant functional effects on gene function and genome evolution. There are different mechanisms through which TEs control the expression of genes. First, TEs offer cis-regulatory regions in the genome with their inherent regulatory features for their own expression, making them potential factors for controlling the expression of the host genes. Promoter and enhancer elements contain cis-regulatory sites generated from TE, which function as binding sites for a variety of trans-acting factors. Second, a significant portion of miRNAs and long non-coding RNAs (lncRNAs) have been shown to have TEs that encode for regulatory RNAs, revealing the TE origin of these RNAs. Furthermore, it was shown that TE sequences are essential for these RNAs' regulatory actions, which include binding to the target mRNA. By being a member of cis-regulatory and regulatory RNA sequences, TEs therefore play essential regulatory roles. Additionally, it has been suggested that TE-derived regulatory RNAs and cis-regulatory regions both contribute to the evolutionary novelty of gene regulation. Additionally, these regulatory systems arising from TE frequently have tissue-specific functions. The objective of this review is to discuss TE-mediated gene regulation, with a particular emphasis on the processes, contributions of various TE types, differential roles of various tissue types, based mostly on recent studies on humans.
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Affiliation(s)
- Alemu Gebrie
- Department of Biomedical Sciences, School of Medicine, Debre Markos University, Debre Markos, Ethiopia.
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7
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Modenini G, Abondio P, Guffanti G, Boattini A, Macciardi F. Evolutionarily recent retrotransposons contribute to schizophrenia. Transl Psychiatry 2023; 13:181. [PMID: 37244930 DOI: 10.1038/s41398-023-02472-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 05/02/2023] [Accepted: 05/12/2023] [Indexed: 05/29/2023] Open
Abstract
Transposable elements (TEs) are mobile genetic elements that constitute half of the human genome. Recent studies suggest that polymorphic non-reference TEs (nrTEs) may contribute to cognitive diseases, such as schizophrenia, through a cis-regulatory effect. The aim of this work is to identify sets of nrTEs putatively linked to an increased risk of developing schizophrenia. To do so, we inspected the nrTE content of genomes from the dorsolateral prefrontal cortex of schizophrenic and control individuals and identified 38 nrTEs that possibly contribute to the emergence of this psychiatric disorder, two of them further confirmed with haplotype-based methods. We then performed in silico functional inferences and found that 9 of the 38 nrTEs act as expression/alternative splicing quantitative trait loci (eQTLs/sQTLs) in the brain, suggesting a possible role in shaping the human cognitive genome structure. To our knowledge, this is the first attempt at identifying polymorphic nrTEs that can contribute to the functionality of the brain. Finally, we suggest that a neurodevelopmental genetic mechanism, which involves evolutionarily young nrTEs, can be key to understanding the ethio-pathogenesis of this complex disorder.
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Affiliation(s)
| | - Paolo Abondio
- BiGeA Department, University of Bologna, Bologna, Italy
- Department of Cultural Heritage, University of Bologna, Ravenna, Italy
| | - Guia Guffanti
- Department of Psychiatry, McLean Hospital-Harvard Medical School, Belmont, MA, USA
| | | | - Fabio Macciardi
- Department of Medical Education (Neuroscience), CUSM, Colton, CA, USA.
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8
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Gasparotto E, Burattin FV, Di Gioia V, Panepuccia M, Ranzani V, Marasca F, Bodega B. Transposable Elements Co-Option in Genome Evolution and Gene Regulation. Int J Mol Sci 2023; 24:ijms24032610. [PMID: 36768929 PMCID: PMC9917352 DOI: 10.3390/ijms24032610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/26/2023] [Accepted: 01/28/2023] [Indexed: 01/31/2023] Open
Abstract
The genome is no longer deemed as a fixed and inert item but rather as a moldable matter that is continuously evolving and adapting. Within this frame, Transposable Elements (TEs), ubiquitous, mobile, repetitive elements, are considered an alive portion of the genomes to date, whose functions, although long considered "dark", are now coming to light. Here we will review that, besides the detrimental effects that TE mobilization can induce, TEs have shaped genomes in their current form, promoting genome sizing, genomic rearrangements and shuffling of DNA sequences. Although TEs are mostly represented in the genomes by evolutionarily old, short, degenerated, and sedentary fossils, they have been thoroughly co-opted by the hosts as a prolific and original source of regulatory instruments for the control of gene transcription and genome organization in the nuclear space. For these reasons, the deregulation of TE expression and/or activity is implicated in the onset and progression of several diseases. It is likely that we have just revealed the outermost layers of TE functions. Further studies on this portion of the genome are required to unlock novel regulatory functions that could also be exploited for diagnostic and therapeutic approaches.
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Affiliation(s)
- Erica Gasparotto
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy
- SEMM, European School of Molecular Medicine, 20139 Milan, Italy
| | - Filippo Vittorio Burattin
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy
- Department of Biosciences, University of Milan, 20133 Milan, Italy
| | - Valeria Di Gioia
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy
- SEMM, European School of Molecular Medicine, 20139 Milan, Italy
| | - Michele Panepuccia
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy
| | - Valeria Ranzani
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy
| | - Federica Marasca
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, 20122 Milan, Italy
| | - Beatrice Bodega
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy
- Department of Biosciences, University of Milan, 20133 Milan, Italy
- Correspondence:
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9
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Modenini G, Abondio P, Guffanti G, Boattini A, Macciardi F. Evolutionarily recent retrotransposons contribute to schizophrenia. RESEARCH SQUARE 2023:rs.3.rs-2474682. [PMID: 36747630 PMCID: PMC9900980 DOI: 10.21203/rs.3.rs-2474682/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Transposable Elements (TEs) are mobile genetic elements that constitute half of the human genome. Recent studies suggest that polymorphic non-reference TEs (nrTEs) may contribute to cognitive diseases, such as schizophrenia, through a cis-regulatory effect. The aim of this work is to identify sets of nrTEs putatively linked to an increased risk of developing schizophrenia. To do so, we inspected the nrTE content of genomes from the Dorsolateral Prefrontal Cortex of schizophrenic and control individuals, and identified 38 nrTEs which possibly contribute to the emergence of this psychiatric disorder. Furthermore, we performed in silico functional inferences and found, for instance, that 9 of the 38 nrTEs act as expression/alternative splicing quantitative trait loci (eQTLs/sQTLs) in the brain, suggesting a possible role in shaping the human cognitive genome structure. Therefore, to our knowledge, this is the first attempt at identifying polymorphic nrTEs that can contribute to the functionality of the brain. Finally, we suggest that a neurodevelopmental genetic mechanism, which involves evolutionarily young nrTEs, can be the key to understanding the ethiopathogenesis of this complex disorder.
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10
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Choudhary A, Peles D, Nayak R, Mizrahi L, Stern S. Current progress in understanding schizophrenia using genomics and pluripotent stem cells: A meta-analytical overview. Schizophr Res 2022:S0920-9964(22)00406-6. [PMID: 36443183 DOI: 10.1016/j.schres.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 10/16/2022] [Accepted: 11/01/2022] [Indexed: 11/27/2022]
Abstract
Schizophrenia (SCZ) is a complex, heritable and polygenic neuropsychiatric disease, which disables the patients as well as decreases their life expectancy and quality of life. Common and rare variants studies on SCZ subjects have provided >100 genomic loci that hold importance in the context of SCZ pathophysiology. Transcriptomic studies from clinical samples have informed about the differentially expressed genes (DEGs) and non-coding RNAs in SCZ patients. Despite these advancements, no causative genes for SCZ were found and hence SCZ is difficult to recapitulate in animal models. In the last decade, induced Pluripotent Stem Cells (iPSCs)-based models have helped in understanding the neural phenotypes of SCZ by studying patient iPSC-derived 2D neuronal cultures and 3D brain organoids. Here, we have aimed to provide a simplistic overview of the current progress and advancements after synthesizing the enormous literature on SCZ genetics and SCZ iPSC-based models. Although further understanding of SCZ genetics and pathophysiological mechanisms using these technological advancements is required, the recent approaches have allowed to delineate important cellular mechanisms and biological pathways affected in SCZ.
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Affiliation(s)
- Ashwani Choudhary
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - David Peles
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Ritu Nayak
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Liron Mizrahi
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Shani Stern
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel.
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11
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Wang J, Weatheritt R, Voineagu I. Alu-minating the Mechanisms Underlying Primate Cortex Evolution. Biol Psychiatry 2022; 92:760-771. [PMID: 35981906 DOI: 10.1016/j.biopsych.2022.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 04/04/2022] [Accepted: 04/28/2022] [Indexed: 11/02/2022]
Abstract
The higher-order cognitive functions observed in primates correlate with the evolutionary enhancement of cortical volume and folding, which in turn are driven by the primate-specific expansion of cellular diversity in the developing cortex. Underlying these changes is the diversification of molecular features including the creation of human and/or primate-specific genes, the activation of specific molecular pathways, and the interplay of diverse layers of gene regulation. We review and discuss evidence for connections between Alu elements and primate brain evolution, the evolutionary milestones of which are known to coincide along primate lineages. Alus are repetitive elements that contribute extensively to the acquisition of novel genes and the expansion of diverse gene regulatory layers, including enhancers, alternative splicing, RNA editing, and microRNA pathways. By reviewing the impact of Alus on molecular features linked to cortical expansions or gyrification or implications in cognitive deficits, we suggest that future research focusing on the role of Alu-derived molecular events in the context of brain development may greatly advance our understanding of higher-order cognitive functions and neurologic disorders.
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Affiliation(s)
- Juli Wang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia.
| | - Robert Weatheritt
- St Vincent Clinical School, University of New South Wales, Sydney, Australia; Garvan Institute of Medical Research, EMBL Australia, Sydney, New South Wales, Australia
| | - Irina Voineagu
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia; Cellular Genomics Futures Institute, University of New South Wales, Sydney, Australia.
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12
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Iourov IY, Vorsanova SG, Kurinnaia OS, Kutsev SI, Yurov YB. Somatic mosaicism in the diseased brain. Mol Cytogenet 2022; 15:45. [PMID: 36266706 PMCID: PMC9585840 DOI: 10.1186/s13039-022-00624-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 11/10/2022] Open
Abstract
It is hard to believe that all the cells of a human brain share identical genomes. Indeed, single cell genetic studies have demonstrated intercellular genomic variability in the normal and diseased brain. Moreover, there is a growing amount of evidence on the contribution of somatic mosaicism (the presence of genetically different cell populations in the same individual/tissue) to the etiology of brain diseases. However, brain-specific genomic variations are generally overlooked during the research of genetic defects associated with a brain disease. Accordingly, a review of brain-specific somatic mosaicism in disease context seems to be required. Here, we overview gene mutations, copy number variations and chromosome abnormalities (aneuploidy, deletions, duplications and supernumerary rearranged chromosomes) detected in the neural/neuronal cells of the diseased brain. Additionally, chromosome instability in non-cancerous brain diseases is addressed. Finally, theoretical analysis of possible mechanisms for neurodevelopmental and neurodegenerative disorders indicates that a genetic background for formation of somatic (chromosomal) mosaicism in the brain is likely to exist. In total, somatic mosaicism affecting the central nervous system seems to be a mechanism of brain diseases.
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Affiliation(s)
- Ivan Y Iourov
- Yurov's Laboratory of Molecular Genetics and Cytogenomics of the Brain, Mental Health Research Center, Moscow, Russia. .,Vorsanova's Laboratory of Molecular Cytogenetics of Neuropsychiatric Diseases, Veltischev Research and Clinical Institute for Pediatrics and Pediatric Surgery of the Pirogov Russian National Research Medical University of the Russian Ministry of Health, Moscow, Russia. .,Department of Medical Biological Disciplines, Belgorod State University, Belgorod, Russia.
| | - Svetlana G Vorsanova
- Yurov's Laboratory of Molecular Genetics and Cytogenomics of the Brain, Mental Health Research Center, Moscow, Russia.,Vorsanova's Laboratory of Molecular Cytogenetics of Neuropsychiatric Diseases, Veltischev Research and Clinical Institute for Pediatrics and Pediatric Surgery of the Pirogov Russian National Research Medical University of the Russian Ministry of Health, Moscow, Russia
| | - Oxana S Kurinnaia
- Yurov's Laboratory of Molecular Genetics and Cytogenomics of the Brain, Mental Health Research Center, Moscow, Russia.,Vorsanova's Laboratory of Molecular Cytogenetics of Neuropsychiatric Diseases, Veltischev Research and Clinical Institute for Pediatrics and Pediatric Surgery of the Pirogov Russian National Research Medical University of the Russian Ministry of Health, Moscow, Russia
| | | | - Yuri B Yurov
- Yurov's Laboratory of Molecular Genetics and Cytogenomics of the Brain, Mental Health Research Center, Moscow, Russia.,Vorsanova's Laboratory of Molecular Cytogenetics of Neuropsychiatric Diseases, Veltischev Research and Clinical Institute for Pediatrics and Pediatric Surgery of the Pirogov Russian National Research Medical University of the Russian Ministry of Health, Moscow, Russia
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13
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Son JH, Do H, Han J. Intragenic L1 Insertion: One Possibility of Brain Disorder. Life (Basel) 2022; 12:life12091425. [PMID: 36143463 PMCID: PMC9505610 DOI: 10.3390/life12091425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 08/29/2022] [Accepted: 09/08/2022] [Indexed: 11/17/2022] Open
Abstract
Long interspersed nuclear element 1 (LINE1, L1) is a retrotransposon comprising ~17% of the human genome. A subset of L1s maintains the potential to mobilize and alter the genomic landscape, consequently contributing to the change in genome integrity and gene expression. L1 retrotransposition occurs in the human brain regardless of disease status. However, in the brain of patients with various brain diseases, the expression level and copy number of L1 are significantly increased. In this review, we briefly introduce the methodologies applied to measure L1 mobility and identify genomic loci where new insertion of L1 occurs in the brain. Then, we present a list of genes disrupted by L1 transposition in the genome of patients with brain disorders. Finally, we discuss the association between genes disrupted by L1 and relative brain disorders.
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Affiliation(s)
- Ji-Hoon Son
- Graduate School of Medical Science and Engineering, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 34141, Korea
| | - Hyunsu Do
- Graduate School of Medical Science and Engineering, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 34141, Korea
| | - Jinju Han
- Graduate School of Medical Science and Engineering, Korea Advanced Institute for Science and Technology (KAIST), Daejeon 34141, Korea
- BioMedical Research Center, KAIST, Daejeon 34141, Korea
- Correspondence:
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14
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Sfera A, Hazan S, Anton JJ, Sfera DO, Andronescu CV, Sasannia S, Rahman L, Kozlakidis Z. Psychotropic drugs interaction with the lipid nanoparticle of COVID-19 mRNA therapeutics. Front Pharmacol 2022; 13:995481. [PMID: 36160443 PMCID: PMC9503827 DOI: 10.3389/fphar.2022.995481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/09/2022] [Indexed: 11/18/2022] Open
Abstract
The messenger RNA (mRNA) vaccines for COVID-19, Pfizer-BioNTech and Moderna, were authorized in the US on an emergency basis in December of 2020. The rapid distribution of these therapeutics around the country and the world led to millions of people being vaccinated in a short time span, an action that decreased hospitalization and death but also heightened the concerns about adverse effects and drug-vaccine interactions. The COVID-19 mRNA vaccines are of particular interest as they form the vanguard of a range of other mRNA therapeutics that are currently in the development pipeline, focusing both on infectious diseases as well as oncological applications. The Vaccine Adverse Event Reporting System (VAERS) has gained additional attention during the COVID-19 pandemic, specifically regarding the rollout of mRNA therapeutics. However, for VAERS, absence of a reporting platform for drug-vaccine interactions left these events poorly defined. For example, chemotherapy, anticonvulsants, and antimalarials were documented to interfere with the mRNA vaccines, but much less is known about the other drugs that could interact with these therapeutics, causing adverse events or decreased efficacy. In addition, SARS-CoV-2 exploitation of host cytochrome P450 enzymes, reported in COVID-19 critical illness, highlights viral interference with drug metabolism. For example, patients with severe psychiatric illness (SPI) in treatment with clozapine often displayed elevated drug levels, emphasizing drug-vaccine interaction.
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Affiliation(s)
- Adonis Sfera
- Patton State Hospital, San Bernardino, CA, United States
- Department of Psychiatry, University of California, Riverside, Riverside, CA, United States
| | - Sabine Hazan
- Department of Psychiatry, University of California, Riverside, Riverside, CA, United States
| | - Jonathan J. Anton
- Patton State Hospital, San Bernardino, CA, United States
- Department of Biology, California Baptist University, Riverside, CA, United States
| | - Dan O. Sfera
- Patton State Hospital, San Bernardino, CA, United States
| | | | | | - Leah Rahman
- Department of Medicine, University of Oregon, Eugene, OR, United States
| | - Zisis Kozlakidis
- International Agency For Research On Cancer (IARC), Lyon, France
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15
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Jahangir M, Li L, Zhou JS, Lang B, Wang XP. L1 Retrotransposons: A Potential Endogenous Regulator for Schizophrenia. Front Genet 2022; 13:878508. [PMID: 35832186 PMCID: PMC9271560 DOI: 10.3389/fgene.2022.878508] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 05/31/2022] [Indexed: 11/13/2022] Open
Abstract
The long interspersed nuclear elements 1 (LINE-1/L1s) are the only active autonomous retrotransposons found in humans which can integrate anywhere in the human genome. They can expand the genome and thus bring good or bad effects to the host cells which really depends on their integration site and associated polymorphism. LINE-1 retrotransposition has been found participating in various neurological disorders such as autism spectrum disorder, Alzheimer’s disease, major depression disorder, post-traumatic stress disorder and schizophrenia. Despite the recent progress, the roles and pathological mechanism of LINE-1 retrotransposition in schizophrenia and its heritable risks, particularly, contribution to “missing heritability” are yet to be determined. Therefore, this review focuses on the potentially etiological roles of L1s in the development of schizophrenia, possible therapeutic choices and unaddressed questions in order to shed lights on the future research.
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Affiliation(s)
| | | | | | - Bing Lang
- *Correspondence: Bing Lang, ; Xiao-Ping Wang,
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16
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DeRosa H, Richter T, Wilkinson C, Hunter RG. Bridging the Gap Between Environmental Adversity and Neuropsychiatric Disorders: The Role of Transposable Elements. Front Genet 2022; 13:813510. [PMID: 35711940 PMCID: PMC9196244 DOI: 10.3389/fgene.2022.813510] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 04/13/2022] [Indexed: 12/21/2022] Open
Abstract
Long regarded as “junk DNA,” transposable elements (TEs) have recently garnered much attention for their role in promoting genetic diversity and plasticity. While many processes involved in mammalian development require TE activity, deleterious TE insertions are a hallmark of several psychiatric disorders. Moreover, stressful events including exposure to gestational infection and trauma, are major risk factors for developing psychiatric illnesses. Here, we will provide evidence demonstrating the intersection of stressful events, atypical TE expression, and their epigenetic regulation, which may explain how neuropsychiatric phenotypes manifest. In this way, TEs may be the “bridge” between environmental perturbations and psychopathology.
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Affiliation(s)
- Holly DeRosa
- Psychology Department, Developmental Brain Sciences Program, College of Liberal Arts, University of Massachusetts Boston, Boston, MA, United States
| | - Troy Richter
- Psychology Department, Developmental Brain Sciences Program, College of Liberal Arts, University of Massachusetts Boston, Boston, MA, United States
| | - Cooper Wilkinson
- Psychology Department, Developmental Brain Sciences Program, College of Liberal Arts, University of Massachusetts Boston, Boston, MA, United States
| | - Richard G Hunter
- Psychology Department, Developmental Brain Sciences Program, College of Liberal Arts, University of Massachusetts Boston, Boston, MA, United States
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17
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Chesnokova E, Beletskiy A, Kolosov P. The Role of Transposable Elements of the Human Genome in Neuronal Function and Pathology. Int J Mol Sci 2022; 23:5847. [PMID: 35628657 PMCID: PMC9148063 DOI: 10.3390/ijms23105847] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 12/13/2022] Open
Abstract
Transposable elements (TEs) have been extensively studied for decades. In recent years, the introduction of whole-genome and whole-transcriptome approaches, as well as single-cell resolution techniques, provided a breakthrough that uncovered TE involvement in host gene expression regulation underlying multiple normal and pathological processes. Of particular interest is increased TE activity in neuronal tissue, and specifically in the hippocampus, that was repeatedly demonstrated in multiple experiments. On the other hand, numerous neuropathologies are associated with TE dysregulation. Here, we provide a comprehensive review of literature about the role of TEs in neurons published over the last three decades. The first chapter of the present review describes known mechanisms of TE interaction with host genomes in general, with the focus on mammalian and human TEs; the second chapter provides examples of TE exaptation in normal neuronal tissue, including TE involvement in neuronal differentiation and plasticity; and the last chapter lists TE-related neuropathologies. We sought to provide specific molecular mechanisms of TE involvement in neuron-specific processes whenever possible; however, in many cases, only phenomenological reports were available. This underscores the importance of further studies in this area.
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Affiliation(s)
- Ekaterina Chesnokova
- Laboratory of Cellular Neurobiology of Learning, Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences, 117485 Moscow, Russia; (A.B.); (P.K.)
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18
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Lee S, Lee JH. Brain somatic mutations as RNA therapeutic targets in neurological disorders. Ann N Y Acad Sci 2022; 1514:11-20. [PMID: 35527236 DOI: 10.1111/nyas.14786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Research into the genetic etiology of a neurological disorder can provide directions for genetic diagnosis and targeted therapy. In the past, germline mutations, which are transmitted from parents or newly arise from parental germ cells, were considered as major genetic causes of neurological disorders. However, recent evidence has shown that somatic mutations in the brain, which can arise from neural stem cells during development or over aging, account for a significant number of brain disorders, ranging from neurodevelopmental, neurodegenerative, and neuropsychiatric to neoplastic disease. Moreover, the identification of disease-causing somatic mutations or mutated genes has provided new insights into molecular pathogenesis and unveiled potential therapeutic targets for treating neurological disorders that have few, or no, therapeutic options. RNA therapeutics, including antisense oligonucleotide (ASO) and small interfering RNA (siRNA), are emerging as promising therapeutic tools for treating genetic neurological disorders. As the number of approved and investigational ASO and siRNA drugs for neurological disorders associated with germline mutations increases, they may also prove to be attractive modalities for treating neurologic disorders resulting from somatic mutations. In this perspective, we highlight several neurological diseases caused by brain somatic mutations and discuss the potential role of RNA therapeutics in these conditions.
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Affiliation(s)
- Sungyul Lee
- SoVarGen Co., Ltd., Daejeon, Republic of Korea
| | - Jeong Ho Lee
- SoVarGen Co., Ltd., Daejeon, Republic of Korea.,Graduate School of Medical Science and Engineering, Korea Advanced Institute Science and Technology (KAIST), KAIST BioMedical Research Center, Daejeon, Republic of Korea
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19
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Transposable Elements and Human Diseases: Mechanisms and Implication in the Response to Environmental Pollutants. Int J Mol Sci 2022; 23:ijms23052551. [PMID: 35269693 PMCID: PMC8910135 DOI: 10.3390/ijms23052551] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/21/2022] [Accepted: 02/22/2022] [Indexed: 02/06/2023] Open
Abstract
Transposable elements (TEs) are recognized as major players in genome plasticity and evolution. The high abundance of TEs in the human genome, especially the Alu and Long Interspersed Nuclear Element-1 (LINE-1) repeats, makes them responsible for the molecular origin of several diseases. This involves several molecular mechanisms that are presented in this review: insertional mutation, DNA recombination and chromosomal rearrangements, modification of gene expression, as well as alteration of epigenetic regulations. This literature review also presents some of the more recent and/or more classical examples of human diseases in which TEs are involved. Whether through insertion of LINE-1 or Alu elements that cause chromosomal rearrangements, or through epigenetic modifications, TEs are widely implicated in the origin of human cancers. Many other human diseases can have a molecular origin in TE-mediated chromosomal recombination or alteration of gene structure and/or expression. These diseases are very diverse and include hemoglobinopathies, metabolic and neurological diseases, and common diseases. Moreover, TEs can also have an impact on aging. Finally, the exposure of individuals to stresses and environmental contaminants seems to have a non-negligible impact on the epigenetic derepression and mobility of TEs, which can lead to the development of diseases. Thus, improving our knowledge of TEs may lead to new potential diagnostic markers of diseases.
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20
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Savino A, Nichols CD. Lysergic acid diethylamide induces increased signalling entropy in rats' prefrontal cortex. J Neurochem 2021; 162:9-23. [PMID: 34729786 PMCID: PMC9298798 DOI: 10.1111/jnc.15534] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 10/20/2021] [Accepted: 10/27/2021] [Indexed: 12/11/2022]
Abstract
Psychedelic drugs are gaining attention from the scientific community as potential new compounds for the treatment of psychiatric diseases such as mood and substance use disorders. The 5‐HT2A receptor has been identified as the main molecular target, and early studies pointed to an effect on the expression of neuroplasticity genes. Analysing RNA‐seq data from the prefrontal cortex of rats chronically treated with lysergic acid diethylamide (LSD), we describe the psychedelic‐induced rewiring of gene co‐expression networks, which become less centralised but more complex, with an overall increase in signalling entropy typical of highly plastic systems. Intriguingly, signalling entropy mirrors, at the molecular level, the increased brain entropy reported through neuroimaging studies in human, suggesting the underlying mechanisms of higher‐order phenomena. Moreover, from the analysis of network topology, we identify potential transcriptional regulators and propose the involvement of different cell types in psychedelics’ activity.
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Affiliation(s)
- Aurora Savino
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin, Italy
| | - Charles D Nichols
- Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
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21
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Saxena S, Choudhury S, Maroju PA, Anne A, Kumar L, Mohan KN. Dysregulation of schizophrenia-associated genes and genome-wide hypomethylation in neurons overexpressing DNMT1. Epigenomics 2021; 13:1539-1555. [PMID: 34647491 DOI: 10.2217/epi-2021-0133] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: To study the effects of DNMT1 overexpression on transcript levels of genes dysregulated in schizophrenia and on genome-wide methylation patterns. Materials & methods: Transcriptome and DNA methylome comparisons were made between R1 (wild-type) and Dnmt1tet/tet mouse embryonic stem cells and neurons overexpressing DNMT1. Genes dysregulated in both Dnmt1tet/tet cells and schizophrenia patients were studied further. Results & conclusions: About 50% of dysregulated genes in patients also showed altered transcript levels in Tet/Tet neurons in a DNA methylation-independent manner. These neurons unexpectedly showed genome-wide hypomethylation, increased transcript levels of Tet1 and Apobec 1-3 genes and increased activity and copy number of LINE-1 elements. The observed similarities between Tet/Tet neurons and schizophrenia brain samples reinforce DNMT1 overexpression as a risk factor.
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Affiliation(s)
- Sonal Saxena
- Department of Biological Sciences, Birla Institute of Technology & Science, Pilani, Hyderabad, 500078, India
| | - Sumana Choudhury
- Department of Biological Sciences, Birla Institute of Technology & Science, Pilani, Hyderabad, 500078, India.,Centre for Human Disease Research, Birla Institute of Technology & Science, Pilani, Hyderabad, 500078, India
| | - Pranay Amruth Maroju
- Department of Biological Sciences, Birla Institute of Technology & Science, Pilani, Hyderabad, 500078, India
| | - Anuhya Anne
- Department of Biological Sciences, Birla Institute of Technology & Science, Pilani, Hyderabad, 500078, India.,Centre for Human Disease Research, Birla Institute of Technology & Science, Pilani, Hyderabad, 500078, India
| | - Lov Kumar
- Computer Science & Information Systems, Birla Institute of Technology & Science, Pilani, Hyderabad, 500078, India
| | - Kommu Naga Mohan
- Department of Biological Sciences, Birla Institute of Technology & Science, Pilani, Hyderabad, 500078, India.,Centre for Human Disease Research, Birla Institute of Technology & Science, Pilani, Hyderabad, 500078, India
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22
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Ravel-Godreuil C, Znaidi R, Bonnifet T, Joshi RL, Fuchs J. Transposable elements as new players in neurodegenerative diseases. FEBS Lett 2021; 595:2733-2755. [PMID: 34626428 DOI: 10.1002/1873-3468.14205] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 09/23/2021] [Accepted: 10/03/2021] [Indexed: 01/02/2023]
Abstract
Neurodegenerative diseases (NDs), including the most prevalent Alzheimer's disease and Parkinson disease, share common pathological features. Despite decades of gene-centric approaches, the molecular mechanisms underlying these diseases remain widely elusive. In recent years, transposable elements (TEs), long considered 'junk' DNA, have gained growing interest as pathogenic players in NDs. Age is the major risk factor for most NDs, and several repressive mechanisms of TEs, such as heterochromatinization, fail with age. Indeed, heterochromatin relaxation leading to TE derepression has been reported in various models of neurodegeneration and NDs. There is also evidence that certain pathogenic proteins involved in NDs (e.g., tau, TDP-43) may control the expression of TEs. The deleterious consequences of TE activation are not well known but they could include DNA damage and genomic instability, altered host gene expression, and/or neuroinflammation, which are common hallmarks of neurodegeneration and aging. TEs might thus represent an overlooked pathogenic culprit for both brain aging and neurodegeneration. Certain pathological effects of TEs might be prevented by inhibiting their activity, pointing to TEs as novel targets for neuroprotection.
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Affiliation(s)
- Camille Ravel-Godreuil
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Rania Znaidi
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Tom Bonnifet
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Rajiv L Joshi
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Julia Fuchs
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
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23
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Factors Regulating the Activity of LINE1 Retrotransposons. Genes (Basel) 2021; 12:genes12101562. [PMID: 34680956 PMCID: PMC8535693 DOI: 10.3390/genes12101562] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/21/2021] [Accepted: 09/22/2021] [Indexed: 12/15/2022] Open
Abstract
LINE-1 (L1) is a class of autonomous mobile genetic elements that form somatic mosaicisms in various tissues of the organism. The activity of L1 retrotransposons is strictly controlled by many factors in somatic and germ cells at all stages of ontogenesis. Alteration of L1 activity was noted in a number of diseases: in neuropsychiatric and autoimmune diseases, as well as in various forms of cancer. Altered activity of L1 retrotransposons for some pathologies is associated with epigenetic changes and defects in the genes involved in their repression. This review discusses the molecular genetic mechanisms of the retrotransposition and regulation of the activity of L1 elements. The contribution of various factors controlling the expression and distribution of L1 elements in the genome occurs at all stages of the retrotransposition. The regulation of L1 elements at the transcriptional, post-transcriptional and integration into the genome stages is described in detail. Finally, this review also focuses on the evolutionary aspects of L1 accumulation and their interplay with the host regulation system.
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24
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Nomura J, Mardo M, Takumi T. Molecular signatures from multi-omics of autism spectrum disorders and schizophrenia. J Neurochem 2021; 159:647-659. [PMID: 34537986 DOI: 10.1111/jnc.15514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 08/11/2021] [Accepted: 09/07/2021] [Indexed: 01/25/2023]
Abstract
The genetic and phenotypic heterogeneity of autism spectrum disorder (ASD) impedes the unification of multiple biological hypotheses in an attempt to explain the complex features of ASD, such as impaired social communication, social interaction deficits, and restricted and repetitive patterns of behavior. However, recent psychiatric genetic studies have identified numerous risk genes and chromosome loci (copy number variation: CNV) which enable us to analyze at the single gene level and utilize system-level approaches. In this review, we focus on ASD as a major neurodevelopmental disorder and review recent findings mainly from the bioinformatics of omics studies. Additionally, by comparing these data with other major psychiatric disorders, including schizophrenia (SCZ), we identify unique characteristics of both diseases from multiple enrichment, pathway, and protein-protein interaction networks (PPIs) analyses using susceptible genes found in recent large-scale genetic studies. These unified, systematic approaches highlight unique characteristics of both disorders from multiple aspects and demonstrate how convergent pathways can contribute to an understanding of the complex etiology of such neurodevelopmental and neuropsychiatric disorders.
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Affiliation(s)
- Jun Nomura
- Department of Physiology and Cell Biology, Kobe University School of Medicine, Kobe, Japan
| | - Matthew Mardo
- Neuroscience concentration, Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Toru Takumi
- Department of Physiology and Cell Biology, Kobe University School of Medicine, Kobe, Japan
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25
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Pappalardo XG, Barra V. Losing DNA methylation at repetitive elements and breaking bad. Epigenetics Chromatin 2021; 14:25. [PMID: 34082816 PMCID: PMC8173753 DOI: 10.1186/s13072-021-00400-z] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 05/21/2021] [Indexed: 02/08/2023] Open
Abstract
Background DNA methylation is an epigenetic chromatin mark that allows heterochromatin formation and gene silencing. It has a fundamental role in preserving genome stability (including chromosome stability) by controlling both gene expression and chromatin structure. Therefore, the onset of an incorrect pattern of DNA methylation is potentially dangerous for the cells. This is particularly important with respect to repetitive elements, which constitute the third of the human genome. Main body Repetitive sequences are involved in several cell processes, however, due to their intrinsic nature, they can be a source of genome instability. Thus, most repetitive elements are usually methylated to maintain a heterochromatic, repressed state. Notably, there is increasing evidence showing that repetitive elements (satellites, long interspersed nuclear elements (LINEs), Alus) are frequently hypomethylated in various of human pathologies, from cancer to psychiatric disorders. Repetitive sequences’ hypomethylation correlates with chromatin relaxation and unscheduled transcription. If these alterations are directly involved in human diseases aetiology and how, is still under investigation. Conclusions Hypomethylation of different families of repetitive sequences is recurrent in many different human diseases, suggesting that the methylation status of these elements can be involved in preservation of human health. This provides a promising point of view towards the research of therapeutic strategies focused on specifically tuning DNA methylation of DNA repeats.
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Affiliation(s)
- Xena Giada Pappalardo
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), University of Catania, 95125, Catania, Italy.,National Council of Research, Institute for Biomedical Research and Innovation (IRIB), Unit of Catania, 95125, Catania, Italy
| | - Viviana Barra
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, 90128, Palermo, Italy.
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26
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Fernandes SB, Grova N, Roth S, Duca RC, Godderis L, Guebels P, Mériaux SB, Lumley AI, Bouillaud-Kremarik P, Ernens I, Devaux Y, Schroeder H, Turner JD. N 6-Methyladenine in Eukaryotic DNA: Tissue Distribution, Early Embryo Development, and Neuronal Toxicity. Front Genet 2021; 12:657171. [PMID: 34108991 PMCID: PMC8181416 DOI: 10.3389/fgene.2021.657171] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/12/2021] [Indexed: 01/09/2023] Open
Abstract
DNA methylation is one of the most important epigenetic modifications and is closely related with several biological processes such as regulation of gene transcription and the development of non-malignant diseases. The prevailing dogma states that DNA methylation in eukaryotes occurs essentially through 5-methylcytosine (5mC) but recently adenine methylation was also found to be present in eukaryotes. In mouse embryonic stem cells, 6-methyladenine (6mA) was associated with the repression and silencing of genes, particularly in the X-chromosome, known to play an important role in cell fate determination. Here, we have demonstrated that 6mA is a ubiquitous eukaryotic epigenetic modification that is put in place during epigenetically sensitive periods such as embryogenesis and fetal development. In somatic cells there are clear tissue specificity in 6mA levels, with the highest 6mA levels being observed in the brain. In zebrafish, during the first 120 h of embryo development, from a single pluripotent cell to an almost fully formed individual, 6mA levels steadily increase. An identical pattern was observed over embryonic days 7–21 in the mouse. Furthermore, exposure to a neurotoxic environmental pollutant during the same early life period may led to a decrease in the levels of this modification in female rats. The identification of the periods during which 6mA epigenetic marks are put in place increases our understanding of this mammalian epigenetic modification, and raises the possibility that it may be associated with developmental processes.
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Affiliation(s)
- Sara B Fernandes
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Esch-sur-Alzette, Luxembourg.,Faculty of Science, Technology and Medicine, University of Luxembourg, Belval, Luxembourg
| | - Nathalie Grova
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Esch-sur-Alzette, Luxembourg.,Calbinotox, EA7488, Faculty of Science and Technology, University of Lorraine, Vandoeuvre-lès-Nancy, France
| | - Sarah Roth
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Esch-sur-Alzette, Luxembourg
| | - Radu Corneliu Duca
- Unit Environmental Hygiene and Human Biological Monitoring, Department of Health Protection, National Health Laboratory (LNS), Dudelange, Luxembourg.,Centre for Environment and Health, Department of Public Health and Primary Care, KU Leuven, Leuven, Belgium
| | - Lode Godderis
- Centre for Environment and Health, Department of Public Health and Primary Care, KU Leuven, Leuven, Belgium.,IDEWE, External Service for Prevention and Protection at Work, Heverlee, Belgium
| | - Pauline Guebels
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Esch-sur-Alzette, Luxembourg
| | - Sophie B Mériaux
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Esch-sur-Alzette, Luxembourg
| | - Andrew I Lumley
- Cardiovascular Research Unit, Department of Public Health, Luxembourg Institute of Health, Strassen, Luxembourg
| | | | - Isabelle Ernens
- Cardiovascular Research Unit, Department of Public Health, Luxembourg Institute of Health, Strassen, Luxembourg
| | - Yvan Devaux
- Cardiovascular Research Unit, Department of Public Health, Luxembourg Institute of Health, Strassen, Luxembourg
| | - Henri Schroeder
- Calbinotox, EA7488, Faculty of Science and Technology, University of Lorraine, Vandoeuvre-lès-Nancy, France
| | - Jonathan D Turner
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Esch-sur-Alzette, Luxembourg
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27
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The "missing heritability"-Problem in psychiatry: Is the interaction of genetics, epigenetics and transposable elements a potential solution? Neurosci Biobehav Rev 2021; 126:23-42. [PMID: 33757815 DOI: 10.1016/j.neubiorev.2021.03.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 03/15/2021] [Accepted: 03/17/2021] [Indexed: 02/07/2023]
Abstract
Psychiatric disorders exhibit an enormous burden on the health care systems worldwide accounting for around one-third of years lost due to disability among adults. Their etiology is largely unknown and diagnostic classification is based on symptomatology and course of illness and not on objective biomarkers. Most psychiatric disorders are moderately to highly heritable. However, it is still unknown what mechanisms may explain the discrepancy between heritability estimates and the present data from genetic analysis. In addition to genetic differences also epigenetic modifications are considered as potentially relevant in the transfer of susceptibility to psychiatric diseases. Though, whether or not epigenetic alterations can be inherited for many generations is highly controversial. In the present article, we will critically summarize both the genetic findings and the results from epigenetic analyses, including also those of noncoding RNAs. We will argue that one possible solution to the "missing heritability" problem in psychiatry is a potential role of retrotransposons, the exploration of which is presently only in its beginnings.
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28
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Reiner BC, Doyle GA, Weller AE, Levinson RN, Rao AM, Davila Perea E, Namoglu E, Pigeon A, Arauco-Shapiro G, Weickert CS, Turecki G, Crist RC, Berrettini WH. Inherited L1 Retrotransposon Insertions Associated With Risk for Schizophrenia and Bipolar Disorder. SCHIZOPHRENIA BULLETIN OPEN 2021; 2:sgab031. [PMID: 34901866 PMCID: PMC8650070 DOI: 10.1093/schizbullopen/sgab031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Studies of the genetic heritability of schizophrenia and bipolar disorder examining single nucleotide polymorphisms (SNPs) and copy number variations have failed to explain a large portion of the genetic liability, resulting in substantial missing heritability. Long interspersed element 1 (L1) retrotransposons are a type of inherited polymorphic variant that may be associated with risk for schizophrenia and bipolar disorder. We performed REBELseq, a genome wide assay for L1 sequences, on DNA from male and female persons with schizophrenia and controls (n = 63 each) to identify inherited L1 insertions and validated priority insertions. L1 insertions of interest were genotyped in DNA from a replication cohort of persons with schizophrenia, bipolar disorder, and controls (n = 2268 each) to examine differences in carrier frequencies. We identified an inherited L1 insertion in ARHGAP24 and a quadallelic SNP (rs74169643) inside an L1 insertion in SNTG2 that are associated with risk for developing schizophrenia and bipolar disorder (all odds ratios ~1.2). Pathway analysis identified 15 gene ontologies that were differentially affected by L1 burden, including multiple ontologies related to glutamatergic signaling and immune function, which have been previously associated with schizophrenia. These findings provide further evidence supporting the role of inherited repetitive genetic elements in the heritability of psychiatric disorders.
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Affiliation(s)
- Benjamin C Reiner
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Glenn A Doyle
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Andrew E Weller
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Rachel N Levinson
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Aditya M Rao
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Emilie Davila Perea
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Esin Namoglu
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alicia Pigeon
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Gabriella Arauco-Shapiro
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Cyndi Shannon Weickert
- Schizophrenia Research Laboratory, Neuroscience Research Australia & School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
- Department of Neuroscience & Physiology, Upstate Medical University, Syracuse, NY, USA
| | - Gustavo Turecki
- McGill Group for Suicide Studies, Douglas Mental Health University Institute, McGill University, Montreal, Canada
| | - Richard C Crist
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Wade H Berrettini
- Molecular and Neural Basis of Psychiatric Disease Section, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Ahmadi A, De Toma I, Vilor-Tejedor N, Eftekhariyan Ghamsari MR, Sadeghi I. Transposable elements in brain health and disease. Ageing Res Rev 2020; 64:101153. [PMID: 32977057 DOI: 10.1016/j.arr.2020.101153] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 07/22/2020] [Accepted: 08/19/2020] [Indexed: 12/17/2022]
Abstract
Transposable elements (TEs) occupy a large fraction of the human genome but only a small proportion of these elements are still active today. Recent works have suggested that TEs are expressed and active in the brain, challenging the dogma that neuronal genomes are static and revealing that they are susceptible to somatic genomic alterations. These new findings have major implications for understanding the neuroplasticity of the brain, which could hypothetically have a role in behavior and cognition, and contribute to vulnerability to disease. As active TEs could induce genetic diversity and mutagenesis, their influences on human brain development and diseases are of great interest. In this review, we will focus on the active TEs in the human genome and discuss in detail their impacts on human brain development. Furthermore, the association between TEs and brain-related diseases is discussed.
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Konzman D, Abramowitz LK, Steenackers A, Mukherjee MM, Na HJ, Hanover JA. O-GlcNAc: Regulator of Signaling and Epigenetics Linked to X-linked Intellectual Disability. Front Genet 2020; 11:605263. [PMID: 33329753 PMCID: PMC7719714 DOI: 10.3389/fgene.2020.605263] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 10/20/2020] [Indexed: 12/13/2022] Open
Abstract
Cellular identity in multicellular organisms is maintained by characteristic transcriptional networks, nutrient consumption, energy production and metabolite utilization. Integrating these cell-specific programs are epigenetic modifiers, whose activity is often dependent on nutrients and their metabolites to function as substrates and co-factors. Emerging data has highlighted the role of the nutrient-sensing enzyme O-GlcNAc transferase (OGT) as an epigenetic modifier essential in coordinating cellular transcriptional programs and metabolic homeostasis. OGT utilizes the end-product of the hexosamine biosynthetic pathway to modify proteins with O-linked β-D-N-acetylglucosamine (O-GlcNAc). The levels of the modification are held in check by the O-GlcNAcase (OGA). Studies from model organisms and human disease underscore the conserved function these two enzymes of O-GlcNAc cycling play in transcriptional regulation, cellular plasticity and mitochondrial reprogramming. Here, we review these findings and present an integrated view of how O-GlcNAc cycling may contribute to cellular memory and transgenerational inheritance of responses to parental stress. We focus on a rare human genetic disorder where mutant forms of OGT are inherited or acquired de novo. Ongoing analysis of this disorder, OGT- X-linked intellectual disability (OGT-XLID), provides a window into how epigenetic factors linked to O-GlcNAc cycling may influence neurodevelopment.
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Affiliation(s)
| | | | | | | | | | - John A. Hanover
- Laboratory of Cellular and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
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31
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Evans TA, Erwin JA. Retroelement-derived RNA and its role in the brain. Semin Cell Dev Biol 2020; 114:68-80. [PMID: 33229216 DOI: 10.1016/j.semcdb.2020.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 10/20/2020] [Accepted: 11/04/2020] [Indexed: 12/17/2022]
Abstract
Comprising ~40% of the human genome, retroelements are mobile genetic elements which are transcribed into RNA, then reverse-transcribed into DNA and inserted into a new site in the genome. Retroelements are referred to as "genetic parasites", residing among host genes and relying on host machinery for transcription and evolutionary propagation. The healthy brain has the highest expression of retroelement-derived sequences compared to other somatic tissue, which leads to the question: how does retroelement-derived RNA influence human traits and cellular states? While the functional importance of upregulating retroelement expression in the brain is an active area of research, RNA species derived from retroelements influence both self- and host gene expression by contributing to chromatin remodeling, alternative splicing, somatic mosaicism and translational repression. Here, we review the emerging evidence that the functional importance of RNA derived from retroelements is multifaceted. Retroelements can influence organismal states through the seeding of epigenetic states in chromatin, the production of structured RNA and even catalytically active ribozymes, the generation of cytoplasmic ssDNA and RNA/DNA hybrids, the production of viral-like proteins, and the generation of somatic mutations. Comparative sequencing suggests that retroelements can contribute to intraspecies variation through these mechanisms to alter transcript identity and abundance. In humans, an increasing number of neurodevelopmental and neurodegenerative conditions are associated with dysregulated retroelements, including Aicardi-Goutieres syndrome (AGS), Rett syndrome (RTT), Amyotrophic Lateral Sclerosis (ALS), Alzheimer's disease (AD), multiple sclerosis (MS), schizophrenia (SZ), and aging. Taken together, these concepts suggest a larger functional role for RNA derived from retroelements. This review aims to define retroelement-derived RNA, discuss how it impacts the mammalian genome, as well as summarize data supporting phenotypic consequences of this unique RNA subset in the brain.
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Affiliation(s)
- Taylor A Evans
- Lieber Institute for Brain Development, Baltimore, MD, USA; Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Jennifer Ann Erwin
- Lieber Institute for Brain Development, Baltimore, MD, USA; Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD, USA; Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, USA.
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Singh SM, Castellani CA, Hill KA. Postzygotic Somatic Mutations in the Human Brain Expand the Threshold-Liability Model of Schizophrenia. Front Psychiatry 2020; 11:587162. [PMID: 33192734 PMCID: PMC7642466 DOI: 10.3389/fpsyt.2020.587162] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 09/22/2020] [Indexed: 12/11/2022] Open
Abstract
The search for what causes schizophrenia has been onerous. This research has included extensive assessment of a variety of genetic and environmental factors using ever emerging high-resolution technologies and traditional understanding of the biology of the brain. These efforts have identified a large number of schizophrenia-associated genes, some of which are altered by mutational and epi-mutational mechanisms in a threshold liability model of schizophrenia development. The results, however, have limited predictability and the actual cause of the disease remains unknown. This current state asks for conceptualizing the problem differently in light of novel insights into the nature of mutations, the biology of the brain and the fine precision and resolution of emerging technologies. There is mounting evidence that mutations acquired during postzygotic development are more common than germline mutations. Also, the postzygotic somatic mutations including epimutations (PZMs), which often lead to somatic mosaicism, are relatively common in the mammalian brain in comparison to most other tissues and PZMs are more common in patients with neurodevelopmental mental disorders, including schizophrenia. Further, previously inaccessible, detection of PZMs is becoming feasible with the advent of novel technologies that include single-cell genomics and epigenomics and the use of exquisite experimental designs including use of monozygotic twins discordant for the disease. These developments allow us to propose a working hypothesis and expand the threshold liability model of schizophrenia that already encompasses familial genetic, epigenetic and environmental factors to include somatic de novo PZMs. Further, we offer a test for this expanded model using currently available genome sequences and methylome data on monozygotic twins discordant for schizophrenia (MZD) and their parents. The results of this analysis argue that PZMs play a significant role in the development of schizophrenia and explain extensive heterogeneity seen across patients. It also offers the potential to convincingly link PZMs to both nervous system health and disease, an area that has remained challenging to study and relatively under explored.
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Affiliation(s)
- Shiva M. Singh
- Molecular Genetics Unit, Department of Biology, The University of Western Ontario, London, ON, Canada
| | | | - Kathleen A. Hill
- Molecular Genetics Unit, Department of Biology, The University of Western Ontario, London, ON, Canada
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Lathe R, St Clair D. From conifers to cognition: Microbes, brain and behavior. GENES BRAIN AND BEHAVIOR 2020; 19:e12680. [PMID: 32515128 DOI: 10.1111/gbb.12680] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 05/12/2020] [Accepted: 05/29/2020] [Indexed: 12/25/2022]
Abstract
A diversity of bacteria, protozoans and viruses ("endozoites") were recently uncovered within healthy tissues including the human brain. By contrast, it was already recognized a century ago that healthy plants tissues contain abundant endogenous microbes ("endophytes"). Taking endophytes as an informative precedent, we overview the nature, prevalence, and role of endozoites in mammalian tissues, centrally focusing on the brain, concluding that endozoites are ubiquitous in diverse tissues. These passengers often remain subclinical, but they are not silent. We address their routes of entry, mechanisms of persistence, tissue specificity, and potential to cause long-term behavioral changes and/or immunosuppression in mammals, where rabies virus is the exemplar. We extend the discussion to Herpesviridae, Coronaviridae, and Toxoplasma, as well as to diverse bacteria and yeasts, and debate the advantages and disadvantages that endozoite infection might afford to the host and to the ecosystem. We provide a clinical perspective in which endozoites are implicated in neurodegenerative disease, anxiety/depression, and schizophrenia. We conclude that endozoites are instrumental in the delicate balance between health and disease, including age-related brain disease, and that endozoites have played an important role in the evolution of brain function and human behavior.
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Affiliation(s)
- Richard Lathe
- Division of Infection Medicine, University of Edinburgh Medical School, Edinburgh, UK
| | - David St Clair
- Institute of Medical Sciences, School of Medicine, University of Aberdeen, Aberdeen, UK
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Jourdon A, Fasching L, Scuderi S, Abyzov A, Vaccarino FM. The role of somatic mosaicism in brain disease. Curr Opin Genet Dev 2020; 65:84-90. [PMID: 32622340 DOI: 10.1016/j.gde.2020.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 04/26/2020] [Accepted: 05/03/2020] [Indexed: 12/25/2022]
Abstract
In this review we discuss the importance of genetic somatic mosaicism and its impact on brain diseases. We start from introducing the different types of somatic mutations, their frequencies and abundances across development and lifespan. We then describe how weakness in DNA repair mechanisms influences their prevalence. Finally, we address their functional consequences in the brain and review recent research showing their unsuspected importance in several neurodevelopmental, psychiatric, and neurodegenerative diseases.
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Affiliation(s)
| | - Liana Fasching
- Child Study Center, Yale University, New Haven, CT 06520, USA
| | - Soraya Scuderi
- Child Study Center, Yale University, New Haven, CT 06520, USA
| | - Alexej Abyzov
- Department of Health Sciences Research, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Flora M Vaccarino
- Child Study Center, Yale University, New Haven, CT 06520, USA; Department of Neuroscience, Yale University, New Haven, CT 06520, USA.
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Jönsson ME, Garza R, Johansson PA, Jakobsson J. Transposable Elements: A Common Feature of Neurodevelopmental and Neurodegenerative Disorders. Trends Genet 2020; 36:610-623. [PMID: 32499105 DOI: 10.1016/j.tig.2020.05.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 05/11/2020] [Accepted: 05/13/2020] [Indexed: 12/30/2022]
Abstract
The etiology of most neurological disorders is poorly understood and current treatments are largely ineffective. New ideas and concepts are therefore vitally important for future research in this area. This review explores the concept that dysregulation of transposable elements (TEs) contributes to the appearance and pathology of neurodevelopmental and neurodegenerative disorders. Despite TEs making up at least half of the human genome, they are vastly understudied in relation to brain disorders. However, recent advances in sequencing technologies and gene editing approaches are now starting to unravel the pathological role of TEs. Aberrant activation of TEs has been found in many neurological disorders; the resulting pathogenic effects, which include alterations of gene expression, neuroinflammation, and direct neurotoxicity, are starting to be resolved. An increased understanding of the relationship between TEs and pathological processes in the brain improves the potential for novel diagnostics and interventions for brain disorders.
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Affiliation(s)
- Marie E Jönsson
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, BMC A11, Lund University, 221 84 Lund, Sweden
| | - Raquel Garza
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, BMC A11, Lund University, 221 84 Lund, Sweden
| | - Pia A Johansson
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, BMC A11, Lund University, 221 84 Lund, Sweden
| | - Johan Jakobsson
- Laboratory of Molecular Neurogenetics, Department of Experimental Medical Science, Wallenberg Neuroscience Center and Lund Stem Cell Center, BMC A11, Lund University, 221 84 Lund, Sweden.
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36
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Terry DM, Devine SE. Aberrantly High Levels of Somatic LINE-1 Expression and Retrotransposition in Human Neurological Disorders. Front Genet 2020; 10:1244. [PMID: 31969897 PMCID: PMC6960195 DOI: 10.3389/fgene.2019.01244] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 11/11/2019] [Indexed: 12/31/2022] Open
Abstract
Retrotransposable elements (RTEs) have actively multiplied over the past 80 million years of primate evolution, and as a consequence, such elements collectively occupy ∼ 40% of the human genome. As RTE activity can have detrimental effects on the human genome and transcriptome, silencing mechanisms have evolved to restrict retrotransposition. The brain is the only known somatic tissue where RTEs are de-repressed throughout the life of a healthy human and each neuron in specific brain regions accumulates up to ∼13.7 new somatic L1 insertions (and perhaps more). However, even higher levels of somatic RTE expression and retrotransposition have been found in a number of human neurological disorders. This review is focused on how RTE expression and retrotransposition in neuronal tissues might contribute to the initiation and progression of these disorders. These disorders are discussed in three broad and sometimes overlapping categories: 1) disorders such as Rett syndrome, Aicardi-Goutières syndrome, and ataxia–telangiectasia, where expression/retrotransposition is increased due to mutations in genes that play a role in regulating RTEs in healthy cells, 2) disorders such as autism spectrum disorder, schizophrenia, and substance abuse disorders, which are thought to be caused by a combination of genetic and environmental stress factors, and 3) disorders associated with age, such as frontotemporal lobar degeneration (FTLD), amyotrophic lateral sclerosis (ALS), and normal aging, where there is a time-dependent accumulation of neurological degeneration, RTE copy number, and phenotypes. Research has revealed increased levels of RTE activity in many neurological disorders, but in most cases, a clear causal link between RTE activity and these disorders has not been well established. At the same time, even if increased RTE activity is a passenger and not a driver of disease, a detrimental effect is more likely than a beneficial one. Thus, a better understanding of the role of RTEs in neuronal tissues likely is an important part of understanding, preventing, and treating these disorders.
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Affiliation(s)
- Diane M Terry
- Molecular Medicine Graduate Program, University of Maryland School of Medicine, Baltimore, MD, United States.,Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Scott E Devine
- Molecular Medicine Graduate Program, University of Maryland School of Medicine, Baltimore, MD, United States.,Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States.,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States.,Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, Baltimore, MD, United States
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Drongitis D, Aniello F, Fucci L, Donizetti A. Roles of Transposable Elements in the Different Layers of Gene Expression Regulation. Int J Mol Sci 2019; 20:ijms20225755. [PMID: 31731828 PMCID: PMC6888579 DOI: 10.3390/ijms20225755] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/12/2019] [Accepted: 11/14/2019] [Indexed: 02/03/2023] Open
Abstract
The biology of transposable elements (TEs) is a fascinating and complex field of investigation. TEs represent a substantial fraction of many eukaryotic genomes and can influence many aspects of DNA function that range from the evolution of genetic information to duplication, stability, and gene expression. Their ability to move inside the genome has been largely recognized as a double-edged sword, as both useful and deleterious effects can result. A fundamental role has been played by the evolution of the molecular processes needed to properly control the expression of TEs. Today, we are far removed from the original reductive vision of TEs as “junk DNA”, and are more convinced that TEs represent an essential element in the regulation of gene expression. In this review, we summarize some of the more recent findings, mainly in the animal kingdom, concerning the active roles that TEs play at every level of gene expression regulation, including chromatin modification, splicing, and protein translation.
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Affiliation(s)
- Denise Drongitis
- Institute of Genetics and Biophysics “Adriano Buzzati Traverso”, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy;
| | - Francesco Aniello
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy; (F.A.); (L.F.)
| | - Laura Fucci
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy; (F.A.); (L.F.)
| | - Aldo Donizetti
- Department of Biology, University of Naples Federico II, 80126 Naples, Italy; (F.A.); (L.F.)
- Correspondence:
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39
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Kato T. Current understanding of bipolar disorder: Toward integration of biological basis and treatment strategies. Psychiatry Clin Neurosci 2019; 73:526-540. [PMID: 31021488 DOI: 10.1111/pcn.12852] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 04/19/2019] [Accepted: 04/22/2019] [Indexed: 12/18/2022]
Abstract
Biological studies of bipolar disorder initially focused on the mechanism of action for antidepressants and antipsychotic drugs, and the roles of monoamines (e.g., serotonin, dopamine) have been extensively studied. Thereafter, based on the mechanism of action of lithium, intracellular signal transduction systems, including inositol metabolism and intracellular calcium signaling, have drawn attention. Involvement of intracellular calcium signaling has been supported by genetics and cellular studies. Elucidation of the neural circuits affected by calcium signaling abnormalities is critical, and our previous study suggested a role of the paraventricular thalamic nucleus. The genetic vulnerability of mitochondria causes calcium dysregulation and results in the hyperexcitability of serotonergic neurons, which are suggested to be susceptible to oxidative stress. Efficacy of anticonvulsants, animal studies of candidate genes, and studies using induced pluripotent stem cell-derived neurons have suggested a relation between bipolar disorder and the hyperexcitability of neurons. Recent genetic findings suggest the roles of polyunsaturated acids. At the systems level, social rhythm therapy targets circadian rhythm abnormalities, and cognitive behavioral therapy may target emotion/cognition (E/C) imbalance. In the future, pharmacological and psychosocial treatments may be combined and optimized based on the biological basis of each patient, which will realize individualized treatment.
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Affiliation(s)
- Tadafumi Kato
- Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Center for Brain Science, Wako, Japan
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40
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Rylaarsdam L, Guemez-Gamboa A. Genetic Causes and Modifiers of Autism Spectrum Disorder. Front Cell Neurosci 2019; 13:385. [PMID: 31481879 PMCID: PMC6710438 DOI: 10.3389/fncel.2019.00385] [Citation(s) in RCA: 246] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/06/2019] [Indexed: 12/18/2022] Open
Abstract
Autism Spectrum Disorder (ASD) is one of the most prevalent neurodevelopmental disorders, affecting an estimated 1 in 59 children. ASD is highly genetically heterogeneous and may be caused by both inheritable and de novo gene variations. In the past decade, hundreds of genes have been identified that contribute to the serious deficits in communication, social cognition, and behavior that patients often experience. However, these only account for 10-20% of ASD cases, and patients with similar pathogenic variants may be diagnosed on very different levels of the spectrum. In this review, we will describe the genetic landscape of ASD and discuss how genetic modifiers such as copy number variation, single nucleotide polymorphisms, and epigenetic alterations likely play a key role in modulating the phenotypic spectrum of ASD patients. We also consider how genetic modifiers can alter convergent signaling pathways and lead to impaired neural circuitry formation. Lastly, we review sex-linked modifiers and clinical implications. Further understanding of these mechanisms is crucial for both comprehending ASD and for developing novel therapies.
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Affiliation(s)
| | - Alicia Guemez-Gamboa
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
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41
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Misiak B, Ricceri L, Sąsiadek MM. Transposable Elements and Their Epigenetic Regulation in Mental Disorders: Current Evidence in the Field. Front Genet 2019; 10:580. [PMID: 31293617 PMCID: PMC6603224 DOI: 10.3389/fgene.2019.00580] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/04/2019] [Indexed: 12/30/2022] Open
Abstract
Transposable elements (TEs) are highly repetitive DNA sequences in the human genome that are the relics of previous retrotransposition events. Although the majority of TEs are transcriptionally inactive due to acquired mutations or epigenetic processes, around 8% of TEs exert transcriptional activity. It has been found that TEs contribute to somatic mosaicism that accounts for functional specification of various brain cells. Indeed, autonomous retrotransposition of long interspersed element-1 (LINE-1) sequences has been reported in the neural rat progenitor cells from the hippocampus, the human fetal brain and the human embryonic stem cells. Moreover, expression of TEs has been found to regulate immune-inflammatory responses, conditioning immunity against exogenous infections. Therefore, aberrant epigenetic regulation and expression of TEs emerged as a potential mechanism underlying the development of various mental disorders, including autism spectrum disorders (ASD), schizophrenia, bipolar disorder, major depression, and Alzheimer's disease (AD). Consequently, some studies revealed that expression of some sequences of human endogenous retroviruses (HERVs) appears only in a certain group of patients with mental disorders (especially those with schizophrenia, bipolar disorder, and ASD) but not in healthy controls. In addition, it has been found that expression of HERVs might be related to subclinical inflammation observed in mental disorders. In this article, we provide an overview of detrimental effects of transposition on the brain development and immune mechanisms with relevance to mental disorders. We show that transposition is not the only mechanism, explaining the way TEs might shape the phenotype of mental disorders. Other mechanisms include the regulation of gene expression and the impact on genomic stability. Next, we review current evidence from studies investigating expression and epigenetic regulation of specific TEs in various mental disorders. Most consistently, these studies indicate altered expression of HERVs and methylation of LINE-1 sequences in patients with ASD, schizophrenia, and mood disorders. However, the contribution of TEs to the etiology of AD is poorly documented. Future studies should further investigate the mechanisms linking epigenetic processes, specific TEs and the phenotype of mental disorders to disentangle causal associations.
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Affiliation(s)
- Błażej Misiak
- Department of Genetics, Wrocław Medical University, Wrocław, Poland
| | - Laura Ricceri
- Centre for Behavioural Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
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Guffanti G, Bartlett A, Klengel T, Klengel C, Hunter R, Glinsky G, Macciardi F. Novel Bioinformatics Approach Identifies Transcriptional Profiles of Lineage-Specific Transposable Elements at Distinct Loci in the Human Dorsolateral Prefrontal Cortex. Mol Biol Evol 2019; 35:2435-2453. [PMID: 30053206 PMCID: PMC6188555 DOI: 10.1093/molbev/msy143] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Expression of transposable elements (TE) is transiently activated during human preimplantation embryogenesis in a developmental stage- and cell type-specific manner and TE-mediated epigenetic regulation is intrinsically wired in developmental genetic networks in human embryos and embryonic stem cells. However, there are no systematic studies devoted to a comprehensive analysis of the TE transcriptome in human adult organs and tissues, including human neural tissues. To investigate TE expression in the human Dorsolateral Prefrontal Cortex (DLPFC), we developed and validated a straightforward analytical approach to chart quantitative genome-wide expression profiles of all annotated TE loci based on unambiguous mapping of discrete TE-encoded transcripts using a de novo assembly strategy. To initially evaluate the potential regulatory impact of DLPFC-expressed TE, we adopted a comparative evolutionary genomics approach across humans, primates, and rodents to document conservation patterns, lineage-specificity, and colocalizations with transcription factor binding sites mapped within primate- and human-specific TE. We identified 654,665 transcripts expressed from 477,507 distinct loci of different TE classes and families, the majority of which appear to have originated from primate-specific sequences. We discovered 4,687 human-specific and transcriptionally active TEs in DLPFC, of which the prominent majority (80.2%) appears spliced. Our analyses revealed significant associations of DLPFC-expressed TE with primate- and human-specific transcription factor binding sites, suggesting potential cross-talks of concordant regulatory functions. We identified 1,689 TEs differentially expressed in the DLPFC of Schizophrenia patients, a majority of which is located within introns of 1,137 protein-coding genes. Our findings imply that identified DLPFC-expressed TEs may affect human brain structures and functions following different evolutionary trajectories. On one side, hundreds of thousands of TEs maintained a remarkably high conservation for ∼8 My of primates’ evolution, suggesting that they are likely conveying evolutionary-constrained primate-specific regulatory functions. In parallel, thousands of transcriptionally active human-specific TE loci emerged more recently, suggesting that they could be relevant for human-specific behavioral or cognitive functions.
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Affiliation(s)
- Guia Guffanti
- Department of Psychiatry, Harvard Medical School, Cambridge, MA.,Division of Depression and Anxiety, McLean Hospital, Belmont, MA
| | - Andrew Bartlett
- Department of Psychology, University of Massachusetts, Boston, MA
| | - Torsten Klengel
- Department of Psychiatry, Harvard Medical School, Cambridge, MA.,Division of Depression and Anxiety, McLean Hospital, Belmont, MA.,Department of Psychiatry and Psychotherapy, University Medical Center Göttingen, Georg-August-University, Goettingen, Germany
| | - Claudia Klengel
- Department of Psychiatry, Harvard Medical School, Cambridge, MA.,Division of Depression and Anxiety, McLean Hospital, Belmont, MA
| | - Richard Hunter
- Department of Psychology, University of Massachusetts, Boston, MA
| | - Gennadi Glinsky
- Translational & Functional Genomics, Institute of Engineering in Medicine, University of California San Diego, La Jolla, CA
| | - Fabio Macciardi
- Department of Psychiatry and Human Behavior, University of California Irvine, Irvine, CA
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43
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Lapp HE, Hunter RG. Early life exposures, neurodevelopmental disorders, and transposable elements. Neurobiol Stress 2019; 11:100174. [PMID: 31193573 PMCID: PMC6536887 DOI: 10.1016/j.ynstr.2019.100174] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 03/27/2019] [Accepted: 05/21/2019] [Indexed: 12/26/2022] Open
Abstract
Transposable elements make up a much larger portion of the genome than protein-coding genes, yet we know relatively little about their function in the human genome. However, we are beginning to more fully understand their role in brain development, neuroinflammation, and adaptation to environmental insults such as stress. For instance, glucocorticoid receptor activation regulates transposable elements in the brain following acute stress. Early life is a period of substantial brain development during which transposable elements play a role. Environmental exposures and experiences during early life that promote abnormal regulation of transposable elements may lead to a cascade of events that ultimately increase susceptibility to disorders later in life. Recent attention to transposable elements in psychiatric illness has begun to clarify associations indicative of dysregulation of different classes of transposable elements in stress-related and neurodevelopmental illness. Though individual susceptibility or resiliency to psychiatric illness has not been explained by traditional genetic studies, the wide inter-individual variability in transposable element composition in the human genome make TEs attractive candidates to elucidate this differential susceptibility. In this review, we discuss evidence that regulation of transposable elements in the brain are stage-specific, sensitive to environmental factors, and may be impacted by early life perturbations. We further present evidence of associations with stress-related and neurodevelopmental psychiatric illness from a developmental perspective.
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Affiliation(s)
- Hannah E Lapp
- University of Massachusetts Boston, 100 Morrissey Blvd Boston, MA, 02125, USA
| | - Richard G Hunter
- University of Massachusetts Boston, 100 Morrissey Blvd Boston, MA, 02125, USA
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44
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Bodea GO, McKelvey EGZ, Faulkner GJ. Retrotransposon-induced mosaicism in the neural genome. Open Biol 2019; 8:rsob.180074. [PMID: 30021882 PMCID: PMC6070720 DOI: 10.1098/rsob.180074] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 06/21/2018] [Indexed: 12/18/2022] Open
Abstract
Over the past decade, major discoveries in retrotransposon biology have depicted the neural genome as a dynamic structure during life. In particular, the retrotransposon LINE-1 (L1) has been shown to be transcribed and mobilized in the brain. Retrotransposition in the developing brain, as well as during adult neurogenesis, provides a milieu in which neural diversity can arise. Dysregulation of retrotransposon activity may also contribute to neurological disease. Here, we review recent reports of retrotransposon activity in the brain, and discuss the temporal nature of retrotransposition and its regulation in neural cells in response to stimuli. We also put forward hypotheses regarding the significance of retrotransposons for brain development and neurological function, and consider the potential implications of this phenomenon for neuropsychiatric and neurodegenerative conditions.
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Affiliation(s)
- Gabriela O Bodea
- Mater Research Institute-University of Queensland, TRI Building, Brisbane, Queensland 4102, Australia .,Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Eleanor G Z McKelvey
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Geoffrey J Faulkner
- Mater Research Institute-University of Queensland, TRI Building, Brisbane, Queensland 4102, Australia .,Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
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45
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Fullard JF, Charney AW, Voloudakis G, Uzilov AV, Haroutunian V, Roussos P. Assessment of somatic single-nucleotide variation in brain tissue of cases with schizophrenia. Transl Psychiatry 2019; 9:21. [PMID: 30655504 PMCID: PMC6336839 DOI: 10.1038/s41398-018-0342-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/15/2018] [Accepted: 11/13/2018] [Indexed: 12/20/2022] Open
Abstract
The genetic architecture of schizophrenia (SCZ) includes numerous risk loci across a range of frequencies and sizes, including common and rare single-nucleotide variants and insertions/deletions (indels), as well as rare copy number variants (CNVs). Despite the clear heritability of the disease, monozygotic twins are discordant for SCZ at a significant rate. Somatic variants-genetic changes that arise after fertilization rather than through germline inheritance-are widespread in the human brain and known to contribute to risk for both rare and common neuropsychiatric conditions. The contribution of somatic variants in the brain to risk of SCZ remains to be determined. In this study, we surveyed somatic single-nucleotide variants (sSNVs) in the brains of controls and individuals with SCZ (n = 10 and n = 9, respectively). From each individual, whole-exome sequencing (WES) was performed on DNA from neuronal and non-neuronal nuclei isolated by fluorescence activated nuclear sorting (FANS) from frozen postmortem prefrontal cortex (PFC) samples, as well as DNA extracted from temporal muscle as a reference. We identified an increased burden of sSNVs in cases compared to controls (SCZ rate = 2.78, control rate = 0.70; P = 0.0092, linear mixed effects model), that included a higher rate of non-synonymous and loss-of-function variants (SCZ rate = 1.33, control rate = 0.50; P = 0.047, linear mixed effects model). Our findings suggest sSNVs in the brain may constitute an additional component of the complex genetic architecture of SCZ. This perspective argues for the need to further investigate somatic variation in the brain as an explanation of the discordance in monozygotic twins and a potential guide to the identification of novel therapeutic targets.
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Affiliation(s)
- John F. Fullard
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029 USA ,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, Institute for Genomics and Multiscale Biology, One Gustave L. Levy Place, New York, NY 10029 USA
| | - Alexander W. Charney
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029 USA ,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, Institute for Genomics and Multiscale Biology, One Gustave L. Levy Place, New York, NY 10029 USA
| | - Georgios Voloudakis
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029 USA
| | - Andrew V. Uzilov
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, Institute for Genomics and Multiscale Biology, One Gustave L. Levy Place, New York, NY 10029 USA ,Sema4, 333 Ludlow Street, Stamford, CT 06902 USA
| | - Vahram Haroutunian
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029 USA ,0000 0004 0420 1184grid.274295.fMental Illness Research, Education, and Clinical Center (VISN 2 South), James J. Peters VA Medical Center, Bronx, NY 10468 USA
| | - Panos Roussos
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029, USA. .,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, Institute for Genomics and Multiscale Biology, One Gustave L. Levy Place, New York, NY, 10029, USA. .,Mental Illness Research, Education, and Clinical Center (VISN 2 South), James J. Peters VA Medical Center, Bronx, NY, 10468, USA.
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46
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Nishioka M, Bundo M, Iwamoto K, Kato T. Somatic mutations in the human brain: implications for psychiatric research. Mol Psychiatry 2019; 24:839-856. [PMID: 30087451 PMCID: PMC6756205 DOI: 10.1038/s41380-018-0129-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 03/27/2018] [Accepted: 05/25/2018] [Indexed: 01/18/2023]
Abstract
Psychiatric disorders such as schizophrenia and bipolar disorder are caused by complex gene-environment interactions. While recent advances in genomic technologies have enabled the identification of several risk variants for psychiatric conditions, including single-nucleotide variants and copy-number variations, these factors can explain only a portion of the liability to these disorders. Although non-inherited factors had previously been attributed to environmental causes, recent genomic analyses have demonstrated that de novo mutations are among the main non-inherited risk factors for several psychiatric conditions. Somatic mutations in the brain may also explain how stochastic developmental events and environmental insults confer risk for a psychiatric disorder following fertilization. Here, we review evidence regarding somatic mutations in the brains of individuals with and without neuropsychiatric diseases. We further discuss the potential biological mechanisms underlying somatic mutations in the brain as well as the technical issues associated with the detection of somatic mutations in psychiatric research.
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Affiliation(s)
- Masaki Nishioka
- 0000 0001 2151 536Xgrid.26999.3dDivision for Counseling and Support, The University of Tokyo, Tokyo, Japan
| | - Miki Bundo
- 0000 0001 0660 6749grid.274841.cDepartment of Molecular Brain Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan ,0000 0004 1754 9200grid.419082.6PRESTO, Japan Science and Technology Agency, Saitama, Japan
| | - Kazuya Iwamoto
- Department of Molecular Brain Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
| | - Tadafumi Kato
- Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Brain Science Institute, Saitama, Japan.
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47
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Abstract
Transposable elements (TEs) are low-complexity elements (e.g., LINEs, SINEs, SVAs, and HERVs) that make up to two-thirds of the human genome. There is mounting evidence that TEs play an essential role in molecular functions that influence genomic plasticity and gene expression regulation. With the advent of next-generation sequencing approaches, our understanding of the relationship between TEs and psychiatric disorders will greatly improve. In this chapter, the Authors comprehensively summarize the state-of the-art of TE research in animal models and humans supporting a framework in which TEs play a functional role in mechanisms affecting a variety of behaviors, including neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. Finally, the Authors discuss recent therapeutic applications raised from the increasing experimental evidence on TE functional mechanisms.
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Affiliation(s)
- G Guffanti
- McLean Hospital - Harvard Medical School, Belmont, MA, USA.
| | - A Bartlett
- Department of Psychology, University of Massachusetts, Boston, Boston, MA, USA
| | - P DeCrescenzo
- McLean Hospital - Harvard Medical School, Belmont, MA, USA
| | - F Macciardi
- Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA
| | - R Hunter
- Department of Psychology, University of Massachusetts, Boston, Boston, MA, USA
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48
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Pereira GC, Sanchez L, Schaughency PM, Rubio-Roldán A, Choi JA, Planet E, Batra R, Turelli P, Trono D, Ostrow LW, Ravits J, Kazazian HH, Wheelan SJ, Heras SR, Mayer J, García-Pérez JL, Goodier JL. Properties of LINE-1 proteins and repeat element expression in the context of amyotrophic lateral sclerosis. Mob DNA 2018; 9:35. [PMID: 30564290 PMCID: PMC6295051 DOI: 10.1186/s13100-018-0138-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 11/15/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease involving loss of motor neurons and having no known cure and uncertain etiology. Several studies have drawn connections between altered retrotransposon expression and ALS. Certain features of the LINE-1 (L1) retrotransposon-encoded ORF1 protein (ORF1p) are analogous to those of neurodegeneration-associated RNA-binding proteins, including formation of cytoplasmic aggregates. In this study we explore these features and consider possible links between L1 expression and ALS. RESULTS We first considered factors that modulate aggregation and subcellular distribution of LINE-1 ORF1p, including nuclear localization. Changes to some ORF1p amino acid residues alter both retrotransposition efficiency and protein aggregation dynamics, and we found that one such polymorphism is present in endogenous L1s abundant in the human genome. We failed, however, to identify CRM1-mediated nuclear export signals in ORF1p nor strict involvement of cell cycle in endogenous ORF1p nuclear localization in human 2102Ep germline teratocarcinoma cells. Some proteins linked with ALS bind and colocalize with L1 ORF1p ribonucleoprotein particles in cytoplasmic RNA granules. Increased expression of several ALS-associated proteins, including TAR DNA Binding Protein (TDP-43), strongly limits cell culture retrotransposition, while some disease-related mutations modify these effects. Using quantitative reverse transcription PCR (RT-qPCR) of ALS tissues and reanalysis of publicly available RNA-Seq datasets, we asked if changes in expression of retrotransposons are associated with ALS. We found minimal altered expression in sporadic ALS tissues but confirmed a previous report of differential expression of many repeat subfamilies in C9orf72 gene-mutated ALS patients. CONCLUSIONS Here we extended understanding of the subcellular localization dynamics of the aggregation-prone LINE-1 ORF1p RNA-binding protein. However, we failed to find compelling evidence for misregulation of LINE-1 retrotransposons in sporadic ALS nor a clear effect of ALS-associated TDP-43 protein on L1 expression. In sum, our study reveals that the interplay of active retrotransposons and the molecular features of ALS are more complex than anticipated. Thus, the potential consequences of altered retrotransposon activity for ALS and other neurodegenerative disorders are worthy of continued investigation.
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Affiliation(s)
- Gavin C. Pereira
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Laura Sanchez
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
| | - Paul M. Schaughency
- Oncology Center-Cancer Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Alejandro Rubio-Roldán
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
| | - Jungbin A. Choi
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Evarist Planet
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Ranjan Batra
- Department of Neurosciences, School of Medicine, University of California at San Diego, San Diego, California USA
| | - Priscilla Turelli
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Didier Trono
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Lyle W. Ostrow
- Neuromuscular Division, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - John Ravits
- Department of Neurosciences, School of Medicine, University of California at San Diego, San Diego, California USA
| | - Haig H. Kazazian
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Sarah J. Wheelan
- Oncology Center-Cancer Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
| | - Sara R. Heras
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
- Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - Jens Mayer
- Department of Human Genetics, Medical Faculty, University of Saarland, Homburg/Saar, Germany
| | - Jose Luis García-Pérez
- GENYO. Centre for Genomics and Oncological Research: Pfizer, University of Granada, Andalusian Regional Government, Granada, Spain
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - John L. Goodier
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland USA
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Li S, Yang Q, Hou Y, Jiang T, Zong L, Wang Z, Luo X, Liang W, Zhao H, Ning Y, Zhao C. Hypomethylation of LINE-1 elements in schizophrenia and bipolar disorder. J Psychiatr Res 2018; 107:68-72. [PMID: 30326341 DOI: 10.1016/j.jpsychires.2018.10.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/01/2018] [Accepted: 10/08/2018] [Indexed: 01/08/2023]
Abstract
Schizophrenia (SCZ) and bipolar disorder (BPD) are severe mental illnesses with evidence of significant genetic and environmental etiological elements in their complex etiologies. 5'-Methylcytosine is the main epigenetic DNA modification that mediates the interplay between genetic and environmental components. In humans, most 5'-methylcytosine modifications are observed in CpG-rich regions within the long interspersed nuclear element (LINE-1). LINE-1 is a mobile retrotransposon that comprises ∼17% of the human genome, and its methylation levels are highly correlated with global DNA methylation levels. LINE-1 insertions are also reported to be mental illnesses-associated genomic risk factors. To examine the LINE-1 methylation levels in SCZ and BPD, this study employed a bisulfite conversion-specific one-label extension (BS-OLE) method to detect the methylation levels at three CpG sites (S1, S2 and S3) of LINE-1 in peripheral blood DNA from a Han Chinese cohort composed of 92 SCZ patients, 99 BPD patients and 92 controls (CON). The results showed a decreased S1 methylation level in SCZ, decreased S2 methylation level in BPD and decreased S3 methylation levels in both SCZ and BPD relative to those of the CON. A female-dependent positive correlation of the S3 methylation level with age in CON became non-significant in both SCZ and BPD. These findings demonstrated that LINE-1 methylation varied with development and disease status. The roles of LINE-1 methylation in the pathogenesis of SCZ and BPD remain to be elucidated.
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Affiliation(s)
- Shufen Li
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Qiong Yang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China; Department of Psychiatry, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong, China
| | - Yu Hou
- Department of Pediatric Neurology, Affiliated BaYi Children's Hospital, PLA Army General Hospital, Beijing, China
| | - Tingyun Jiang
- The Third People's Hospital of Zhongshan, Zhongshan, Guangdong, China
| | - Lu Zong
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Zhongju Wang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Xia Luo
- Faculty of Forensic Medicine, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Wenquan Liang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Hu Zhao
- Faculty of Forensic Medicine, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
| | - Yuping Ning
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China; Department of Psychiatry, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, Guangdong, China.
| | - Cunyou Zhao
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China; Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, Guangdong, China.
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50
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Somatic mosaicism and neurodevelopmental disease. Nat Neurosci 2018; 21:1504-1514. [PMID: 30349109 DOI: 10.1038/s41593-018-0257-3] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 09/21/2018] [Indexed: 12/19/2022]
Abstract
Traditionally, we have considered genetic mutations that cause neurodevelopmental diseases to be inherited or de novo germline mutations. Recently, we have come to appreciate the importance of de novo somatic mutations, which occur postzygotically and are thus present in only a subset of the cells of an affected individual. The advent of next-generation sequencing and single-cell sequencing technologies has shown that somatic mutations contribute to normal and abnormal human brain development. Somatic mutations are one important cause of neuronal migration and brain overgrowth disorders, as suggested by visible focal lesions. In addition, somatic mutations contribute to neurodevelopmental diseases without visible lesions, including epileptic encephalopathies, intellectual disability, and autism spectrum disorder, and may contribute to a broad range of neuropsychiatric diseases. Studying somatic mutations provides insight into the mechanisms underlying human brain development and neurodevelopmental diseases and has important implications for diagnosis and treatment.
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