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Bayat H, Mirahmadi M, Azarshin Z, Ohadi H, Delbari A, Ohadi M. CRISPR/Cas9-mediated deletion of a GA-repeat in human GPM6B leads to disruption of neural cell differentiation from NT2 cells. Sci Rep 2024; 14:2136. [PMID: 38273037 PMCID: PMC10810867 DOI: 10.1038/s41598-024-52675-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 01/22/2024] [Indexed: 01/27/2024] Open
Abstract
The human neuron-specific gene, GPM6B (Glycoprotein membrane 6B), is considered a key gene in neural cell functionality. This gene contains an exceptionally long and strictly monomorphic short tandem repeat (STR) of 9-repeats, (GA)9. STRs in regulatory regions, may impact on the expression of nearby genes. We used CRISPR-based tool to delete this GA-repeat in NT2 cells, and analyzed the consequence of this deletion on GPM6B expression. Subsequently, the edited cells were induced to differentiate into neural cells, using retinoic acid (RA) treatment. Deletion of the GA-repeat significantly decreased the expression of GPM6B at the RNA (p < 0.05) and protein (40%) levels. Compared to the control cells, the edited cells showed dramatic decrease of the astrocyte and neural cell markers, including GFAP (0.77-fold), TUBB3 (0.57-fold), and MAP2 (0.2-fold). Subsequent sorting of the edited cells showed an increased number of NES (p < 0.01), but a decreased number of GFAP (p < 0.001), TUBB3 (p < 0.05), and MAP2 (p < 0.01), compared to the control cells. In conclusion, CRISPR/Cas9-mediated deletion of a GA-repeat in human GPM6B, led to decreased expression of this gene, which in turn, disrupted differentiation of NT2 cells into neural cells.
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Affiliation(s)
- Hadi Bayat
- Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Postal Code: 1985713834, Iran
- Department of Molecular Genetics, Faculty of Biological Sciences, Tarbiat Modares University, Postal Box: 331-14115, Tehran, Iran
| | - Maryam Mirahmadi
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Postal Box: 331-14115, Tehran, Iran
- Department of Exomine, PardisGene Company, Tehran, Postal Code: 1917635816, Iran
| | - Zohreh Azarshin
- Department of Molecular Genetics, Faculty of Biological Sciences, Tarbiat Modares University, Postal Box: 331-14115, Tehran, Iran
| | - Hamid Ohadi
- School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Ahmad Delbari
- Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Postal Code: 1985713834, Iran
| | - Mina Ohadi
- Iranian Research Center on Aging, University of Social Welfare and Rehabilitation Sciences, Tehran, Postal Code: 1985713834, Iran.
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Medina-Suárez S, Machín F. The CRISPR/Cas9 system forms a condensate in the yeast nucleus. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001039. [PMID: 38287928 PMCID: PMC10823498 DOI: 10.17912/micropub.biology.001039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/13/2023] [Accepted: 01/08/2024] [Indexed: 01/31/2024]
Abstract
CRISPR/Cas9 gene editing technology has revolutionized genetic engineering. However, the nuclear dynamics of Cas9 in eukaryotic cells, particularly in the model organism Saccharomyces cerevisiae , remains poorly understood. Here, we constructed yeast strains expressing fluorescently tagged Cas9 variants, revealing their accumulation in the nucleus over time. Notably, Cas9 was non-uniformly distributed in the nucleoplasm during the initial hours, suggesting the formation of a condensate. This condensate often co-localizes with the nucleolus and associates the target site to its periphery. Our findings provide insights into Cas9 nuclear dynamics in yeast, advancing our understanding of CRISPR/Cas9-based genetic manipulation.
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Affiliation(s)
- Sara Medina-Suárez
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Canary Islands, Spain
- Instituto de Tecnologías Biomédicas, Universidad de La Laguna, San Cristóbal de La Laguna, Canary Islands, Spain
| | - Félix Machín
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Canary Islands, Spain
- Instituto de Tecnologías Biomédicas, Universidad de La Laguna, San Cristóbal de La Laguna, Canary Islands, Spain
- Facultad de Ciencias de la Salud, Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Canary Islands, Spain
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3
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Polleys EJ, Del Priore I, Haber JE, Freudenreich CH. Structure-forming CAG/CTG repeats interfere with gap repair to cause repeat expansions and chromosome breaks. Nat Commun 2023; 14:2469. [PMID: 37120647 PMCID: PMC10148874 DOI: 10.1038/s41467-023-37901-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 04/04/2023] [Indexed: 05/01/2023] Open
Abstract
Expanded CAG/CTG repeats are sites of DNA damage, leading to repeat length changes. Homologous recombination (HR) is one cause of repeat instability and we hypothesized that gap filling was a driver of repeat instability during HR. To test this, we developed an assay such that resection and ssDNA gap fill-in would occur across a (CAG)70 or (CTG)70 repeat tract. When the ssDNA template was a CTG sequence, there were increased repeat contractions and a fragile site was created leading to large-scale deletions. When the CTG sequence was on the resected strand, resection was inhibited, resulting in repeat expansions. Increased nucleolytic processing by deletion of Rad9, the ortholog of 53BP1, rescued repeat instability and chromosome breakage. Loss of Rad51 increased contractions implicating a protective role for Rad51 on ssDNA. Together, our work implicates structure-forming repeats as an impediment to resection and gap-filling which can lead to mutations and large-scale deletions.
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Affiliation(s)
- Erica J Polleys
- Department of Biology, Tufts University, Medford, MA, 02155, USA.
| | | | - James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, 02454, USA
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Antony JS, Hinz JM, Wyrick JJ. Tips, Tricks, and Potential Pitfalls of CRISPR Genome Editing in Saccharomyces cerevisiae. Front Bioeng Biotechnol 2022; 10:924914. [PMID: 35706506 PMCID: PMC9190257 DOI: 10.3389/fbioe.2022.924914] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 05/16/2022] [Indexed: 12/26/2022] Open
Abstract
The versatility of clustered regularly interspaced short palindromic repeat (CRISPR)-associated (Cas) genome editing makes it a popular tool for many research and biotechnology applications. Recent advancements in genome editing in eukaryotic organisms, like fungi, allow for precise manipulation of genetic information and fine-tuned control of gene expression. Here, we provide an overview of CRISPR genome editing technologies in yeast, with a particular focus on Saccharomyces cerevisiae. We describe the tools and methods that have been previously developed for genome editing in Saccharomyces cerevisiae and discuss tips and experimental tricks for promoting efficient, marker-free genome editing in this model organism. These include sgRNA design and expression, multiplexing genome editing, optimizing Cas9 expression, allele-specific editing in diploid cells, and understanding the impact of chromatin on genome editing. Finally, we summarize recent studies describing the potential pitfalls of using CRISPR genome targeting in yeast, including the induction of background mutations.
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Affiliation(s)
- Jacob S. Antony
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States
| | - John M. Hinz
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States
| | - John J. Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States
- Center for Reproductive Biology, Washington State University, Pullman, WA, United States
- *Correspondence: John J. Wyrick,
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5
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Mechanistic and Therapeutic Insights into Ataxic Disorders with Pentanucleotide Expansions. Cells 2022; 11:cells11091567. [PMID: 35563872 PMCID: PMC9099484 DOI: 10.3390/cells11091567] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/02/2022] [Accepted: 05/05/2022] [Indexed: 02/01/2023] Open
Abstract
Pentanucleotide expansion diseases constitute a special class of neurodegeneration. The repeat expansions occur in non-coding regions, have likely arisen from Alu elements, and often result in autosomal dominant or recessive phenotypes with underlying cerebellar neuropathology. When transcribed (potentially bidirectionally), the expanded RNA forms complex secondary and tertiary structures that can give rise to RNA-mediated toxicity, including protein sequestration, pentapeptide synthesis, and mRNA dysregulation. Since several of these diseases have recently been discovered, our understanding of their pathological mechanisms is limited, and their therapeutic interventions underexplored. This review aims to highlight new in vitro and in vivo insights into these incurable diseases.
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Rawal CC, Butova NL, Mitra A, Chiolo I. An Expanding Toolkit for Heterochromatin Repair Studies. Genes (Basel) 2022; 13:genes13030529. [PMID: 35328082 PMCID: PMC8955653 DOI: 10.3390/genes13030529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 12/04/2022] Open
Abstract
Pericentromeric heterochromatin is mostly composed of repetitive DNA sequences prone to aberrant recombination. Cells have developed highly specialized mechanisms to enable ‘safe’ homologous recombination (HR) repair while preventing aberrant recombination in this domain. Understanding heterochromatin repair responses is essential to understanding the critical mechanisms responsible for genome integrity and tumor suppression. Here, we review the tools, approaches, and methods currently available to investigate double-strand break (DSB) repair in pericentromeric regions, and also suggest how technologies recently developed for euchromatin repair studies can be adapted to characterize responses in heterochromatin. With this ever-growing toolkit, we are witnessing exciting progress in our understanding of how the ‘dark matter’ of the genome is repaired, greatly improving our understanding of genome stability mechanisms.
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Cardinali B, Provenzano C, Izzo M, Voellenkle C, Battistini J, Strimpakos G, Golini E, Mandillo S, Scavizzi F, Raspa M, Perfetti A, Baci D, Lazarevic D, Garcia-Manteiga JM, Gourdon G, Martelli F, Falcone G. Time-controlled and muscle-specific CRISPR/Cas9-mediated deletion of CTG-repeat expansion in the DMPK gene. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 27:184-199. [PMID: 34976437 PMCID: PMC8693309 DOI: 10.1016/j.omtn.2021.11.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 11/28/2021] [Indexed: 12/14/2022]
Abstract
CRISPR/Cas9-mediated therapeutic gene editing is a promising technology for durable treatment of incurable monogenic diseases such as myotonic dystrophies. Gene-editing approaches have been recently applied to in vitro and in vivo models of myotonic dystrophy type 1 (DM1) to delete the pathogenic CTG-repeat expansion located in the 3′ untranslated region of the DMPK gene. In DM1-patient-derived cells removal of the expanded repeats induced beneficial effects on major hallmarks of the disease with reduction in DMPK transcript-containing ribonuclear foci and reversal of aberrant splicing patterns. Here, we set out to excise the triplet expansion in a time-restricted and cell-specific fashion to minimize the potential occurrence of unintended events in off-target genomic loci and select for the target cell type. To this aim, we employed either a ubiquitous promoter-driven or a muscle-specific promoter-driven Cas9 nuclease and tetracycline repressor-based guide RNAs. A dual-vector approach was used to deliver the CRISPR/Cas9 components into DM1 patient-derived cells and in skeletal muscle of a DM1 mouse model. In this way, we obtained efficient and inducible gene editing both in proliferating cells and differentiated post-mitotic myocytes in vitro as well as in skeletal muscle tissue in vivo.
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Affiliation(s)
- Beatrice Cardinali
- Institute of Biochemistry and Cell Biology, National Research Council, Monterotondo, 00015 Rome, Italy
| | - Claudia Provenzano
- Institute of Biochemistry and Cell Biology, National Research Council, Monterotondo, 00015 Rome, Italy
| | - Mariapaola Izzo
- Institute of Biochemistry and Cell Biology, National Research Council, Monterotondo, 00015 Rome, Italy
| | - Christine Voellenkle
- Molecular Cardiology Laboratory, IRCCS Policlinico San Donato, San Donato Milanese, 20097 Milan, Italy
| | - Jonathan Battistini
- Institute of Biochemistry and Cell Biology, National Research Council, Monterotondo, 00015 Rome, Italy
| | - Georgios Strimpakos
- Institute of Biochemistry and Cell Biology, National Research Council, Monterotondo, 00015 Rome, Italy
| | - Elisabetta Golini
- Institute of Biochemistry and Cell Biology, National Research Council, Monterotondo, 00015 Rome, Italy
| | - Silvia Mandillo
- Institute of Biochemistry and Cell Biology, National Research Council, Monterotondo, 00015 Rome, Italy
| | - Ferdinando Scavizzi
- Institute of Biochemistry and Cell Biology, National Research Council, Monterotondo, 00015 Rome, Italy
| | - Marcello Raspa
- Institute of Biochemistry and Cell Biology, National Research Council, Monterotondo, 00015 Rome, Italy
| | - Alessandra Perfetti
- Molecular Cardiology Laboratory, IRCCS Policlinico San Donato, San Donato Milanese, 20097 Milan, Italy
| | - Denisa Baci
- Molecular Cardiology Laboratory, IRCCS Policlinico San Donato, San Donato Milanese, 20097 Milan, Italy
| | - Dejan Lazarevic
- Center for Omics Sciences, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | | | - Geneviève Gourdon
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, 75013 Paris, France
| | - Fabio Martelli
- Molecular Cardiology Laboratory, IRCCS Policlinico San Donato, San Donato Milanese, 20097 Milan, Italy
| | - Germana Falcone
- Institute of Biochemistry and Cell Biology, National Research Council, Monterotondo, 00015 Rome, Italy
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Abstract
At fifteen different genomic locations, the expansion of a CAG/CTG repeat causes a neurodegenerative or neuromuscular disease, the most common being Huntington's disease and myotonic dystrophy type 1. These disorders are characterized by germline and somatic instability of the causative CAG/CTG repeat mutations. Repeat lengthening, or expansion, in the germline leads to an earlier age of onset or more severe symptoms in the next generation. In somatic cells, repeat expansion is thought to precipitate the rate of disease. The mechanisms underlying repeat instability are not well understood. Here we review the mammalian model systems that have been used to study CAG/CTG repeat instability, and the modifiers identified in these systems. Mouse models have demonstrated prominent roles for proteins in the mismatch repair pathway as critical drivers of CAG/CTG instability, which is also suggested by recent genome-wide association studies in humans. We draw attention to a network of connections between modifiers identified across several systems that might indicate pathway crosstalk in the context of repeat instability, and which could provide hypotheses for further validation or discovery. Overall, the data indicate that repeat dynamics might be modulated by altering the levels of DNA metabolic proteins, their regulation, their interaction with chromatin, or by direct perturbation of the repeat tract. Applying novel methodologies and technologies to this exciting area of research will be needed to gain deeper mechanistic insight that can be harnessed for therapies aimed at preventing repeat expansion or promoting repeat contraction.
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Affiliation(s)
- Vanessa C. Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA,Department of Neurology, Harvard Medical School, Boston, MA, USA,Correspondence to: Vanessa C. Wheeler, Center for Genomic Medicine, Massachusetts Hospital, Boston MAA 02115, USA. E-mail: . and Vincent Dion, UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ Cardiff, UK. E-mail:
| | - Vincent Dion
- UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, UK,Correspondence to: Vanessa C. Wheeler, Center for Genomic Medicine, Massachusetts Hospital, Boston MAA 02115, USA. E-mail: . and Vincent Dion, UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ Cardiff, UK. E-mail:
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De Serres-Bérard T, Pierre M, Chahine M, Puymirat J. Deciphering the mechanisms underlying brain alterations and cognitive impairment in congenital myotonic dystrophy. Neurobiol Dis 2021; 160:105532. [PMID: 34655747 DOI: 10.1016/j.nbd.2021.105532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/24/2021] [Accepted: 10/11/2021] [Indexed: 12/13/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystemic and heterogeneous disorder caused by the expansion of CTG repeats in the 3' UTR of the myotonic dystrophy protein kinase (DMPK) gene. There is a congenital form (CDM1) of the disease characterized by severe hypotonia, respiratory insufficiency as well as developmental delays and intellectual disabilities. CDM1 infants manifest important brain structure abnormalities present from birth while, in contrast, older patients with adult-onset DM1 often present neurodegenerative features and milder progressive cognitive deficits. Promising therapies targeting central molecular mechanisms contributing to the symptoms of adult-onset DM1 are currently in development, but their relevance for treating cognitive impairment in CDM1, which seems to be a partially distinct neurodevelopmental disorder, remain to be elucidated. Here, we provide an update on the clinical presentation of CDM1 and review recent in vitro and in vivo models that have provided meaningful insights on its consequences in development, with a particular focus on the brain. We discuss how enhanced toxic gain-of-function of the mutated DMPK transcripts with larger CUG repeats and the resulting dysregulation of RNA-binding proteins may affect the developing cortex in utero. Because the methylation of CpG islets flanking the trinucleotide repeats has emerged as a strong biomarker of CDM1, we highlight the need to investigate the tissue-specific impacts of these chromatin modifications in the brain. Finally, we outline promising potential therapeutic treatments for CDM1 and propose future in vitro and in vivo models with great potential to shed light on this disease.
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Affiliation(s)
- Thiéry De Serres-Bérard
- LOEX, CHU de Québec-Université Laval Research Center, Quebec City, Canada; CERVO Brain Research Center, Institut universitaire en santé mentale de Québec, Quebec City, Canada
| | - Marion Pierre
- CERVO Brain Research Center, Institut universitaire en santé mentale de Québec, Quebec City, Canada
| | - Mohamed Chahine
- CERVO Brain Research Center, Institut universitaire en santé mentale de Québec, Quebec City, Canada; Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, Canada.
| | - Jack Puymirat
- LOEX, CHU de Québec-Université Laval Research Center, Quebec City, Canada; Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, Canada
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Polleys EJ, Freudenreich CH. Homologous recombination within repetitive DNA. Curr Opin Genet Dev 2021; 71:143-153. [PMID: 34464817 DOI: 10.1016/j.gde.2021.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 08/06/2021] [Accepted: 08/12/2021] [Indexed: 12/16/2022]
Abstract
Many microsatellite DNA sequences are able to form non-B form DNA secondary structures, such as hairpin loops, cruciforms, triplex DNA or G-quadruplexes. These DNA structures can form a significant impediment to DNA replication and repair, leading to DNA nicks, gaps, and breaks, which can be repaired by homologous recombination (HR). Recent work understanding HR at structure-forming repeats has focused on genetic requirements for replication fork restart, break induced replication (BIR) at broken forks, recombination during and after relocalization of breaks or stalled forks to the nuclear periphery, and how repair pathway choice and kinetics are navigated in the presence of a repeat tract. In this review, we summarize recent developments that illuminate the role of recombination in repairing DNA damage or causing tract length changes within repetitive DNA and its role in maintaining genome stability.
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Affiliation(s)
- Erica J Polleys
- Department of Biology, Tufts University, Medford MA 02155, United States
| | - Catherine H Freudenreich
- Department of Biology, Tufts University, Medford MA 02155, United States; Program in Genetics, Tufts University, Boston MA 02111, United States.
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Unravelling roles of error-prone DNA polymerases in shaping cancer genomes. Oncogene 2021; 40:6549-6565. [PMID: 34663880 PMCID: PMC8639439 DOI: 10.1038/s41388-021-02032-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 09/01/2021] [Accepted: 09/20/2021] [Indexed: 12/12/2022]
Abstract
Mutagenesis is a key hallmark and enabling characteristic of cancer cells, yet the diverse underlying mutagenic mechanisms that shape cancer genomes are not understood. This review will consider the emerging challenge of determining how DNA damage response pathways-both tolerance and repair-act upon specific forms of DNA damage to generate mutations characteristic of tumors. DNA polymerases are typically the ultimate mutagenic effectors of DNA repair pathways. Therefore, understanding the contributions of DNA polymerases is critical to develop a more comprehensive picture of mutagenic mechanisms in tumors. Selection of an appropriate DNA polymerase-whether error-free or error-prone-for a particular DNA template is critical to the maintenance of genome stability. We review different modes of DNA polymerase dysregulation including mutation, polymorphism, and over-expression of the polymerases themselves or their associated activators. Based upon recent findings connecting DNA polymerases with specific mechanisms of mutagenesis, we propose that compensation for DNA repair defects by error-prone polymerases may be a general paradigm molding the mutational landscape of cancer cells. Notably, we demonstrate that correlation of error-prone polymerase expression with mutation burden in a subset of patient tumors from The Cancer Genome Atlas can identify mechanistic hypotheses for further testing. We contrast experimental approaches from broad, genome-wide strategies to approaches with a narrower focus on a few hundred base pairs of DNA. In addition, we consider recent developments in computational annotation of patient tumor data to identify patterns of mutagenesis. Finally, we discuss the innovations and future experiments that will develop a more comprehensive portrait of mutagenic mechanisms in human tumors.
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Brown RE, Freudenreich CH. Structure-forming repeats and their impact on genome stability. Curr Opin Genet Dev 2020; 67:41-51. [PMID: 33279816 DOI: 10.1016/j.gde.2020.10.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/22/2020] [Accepted: 10/24/2020] [Indexed: 12/12/2022]
Abstract
Repetitive sequences throughout the genome are a major source of endogenous DNA damage, due to the propensity of many of them to form alternative non-B DNA structures that can interfere with replication, transcription, and DNA repair. These repetitive sequences are prone to breakage (fragility) and instability (changes in repeat number). Repeat fragility and expansions are linked to several diseases, including many cancers and neurodegenerative diseases, hence the importance of understanding the mechanisms that cause genome instability and contribute to these diseases. This review focuses on recent findings of mechanisms causing repeat fragility and instability, new associations between repeat expansions and genetic diseases, and potential therapeutic options to target repeat expansions.
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Affiliation(s)
- Rebecca E Brown
- Program in Genetics, Tufts University Graduate School of Biomedical Sciences, Boston, MA 02111, USA
| | - Catherine H Freudenreich
- Department of Biology, Tufts University, Medford, MA 02155, USA; Program in Genetics, Tufts University Graduate School of Biomedical Sciences, Boston, MA 02111, USA.
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