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Eisel MLS, Burns M, Ashizawa T, Byrne B, Corti M, Subramony SH. Emerging therapies in hereditary ataxias. Trends Mol Med 2024:S1471-4914(24)00194-1. [PMID: 39153956 DOI: 10.1016/j.molmed.2024.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 07/15/2024] [Accepted: 07/22/2024] [Indexed: 08/19/2024]
Abstract
Recent investigations have defined the pathophysiological basis of many hereditary ataxias (HAs), including loss-of-function as well as gain-of-function mechanisms at either the RNA or protein level. Preclinical studies have assessed gene editing, gene and protein replacement, gene enhancement, and gene knockdown strategies. Methodologies include viral vector delivery of genes, oligonucleotide therapies, cell-penetrating peptides, synthetic transcription factors, and technologies to deliver therapies to defined targets. In this review, we focus on Friedreich ataxia (FRDA) and the polyglutamine ataxias in which translational research is active. However, much remains to be done to identify safe and effective molecules, create ideal delivery methods, and perform innovative clinical trials to prove the safety and efficacy of treatments for these rare but devastating diseases.
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Affiliation(s)
- Mallory L S Eisel
- Department of Neurology and the Fixel Institute for Neurological Disorders, University of Florida College of Medicine, Gainesville, FL, USA
| | - Matthew Burns
- Department of Neurology and the Fixel Institute for Neurological Disorders, University of Florida College of Medicine, Gainesville, FL, USA
| | - Tetsuo Ashizawa
- Stanley H. Appel Department of Neurology, Weill Cornell Medicine at Houston Methodist Hospital, Houston, TX, USA
| | - Barry Byrne
- Department of Pediatrics and the Powell Gene Therapy Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Manuela Corti
- Department of Pediatrics and the Powell Gene Therapy Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Sub H Subramony
- Department of Neurology and the Fixel Institute for Neurological Disorders, University of Florida College of Medicine, Gainesville, FL, USA.
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2
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Leckie J, Yokota T. Potential of Cell-Penetrating Peptide-Conjugated Antisense Oligonucleotides for the Treatment of SMA. Molecules 2024; 29:2658. [PMID: 38893532 PMCID: PMC11173757 DOI: 10.3390/molecules29112658] [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: 05/06/2024] [Revised: 05/28/2024] [Accepted: 05/29/2024] [Indexed: 06/21/2024] Open
Abstract
Spinal muscular atrophy (SMA) is a severe neuromuscular disorder that is caused by mutations in the survival motor neuron 1 (SMN1) gene, hindering the production of functional survival motor neuron (SMN) proteins. Antisense oligonucleotides (ASOs), a versatile DNA-like drug, are adept at binding to target RNA to prevent translation or promote alternative splicing. Nusinersen is an FDA-approved ASO for the treatment of SMA. It effectively promotes alternative splicing in pre-mRNA transcribed from the SMN2 gene, an analog of the SMN1 gene, to produce a greater amount of full-length SMN protein, to compensate for the loss of functional protein translated from SMN1. Despite its efficacy in ameliorating SMA symptoms, the cellular uptake of these ASOs is suboptimal, and their inability to penetrate the CNS necessitates invasive lumbar punctures. Cell-penetrating peptides (CPPs), which can be conjugated to ASOs, represent a promising approach to improve the efficiency of these treatments for SMA and have the potential to transverse the blood-brain barrier to circumvent the need for intrusive intrathecal injections and their associated adverse effects. This review provides a comprehensive analysis of ASO therapies, their application for the treatment of SMA, and the encouraging potential of CPPs as delivery systems to improve ASO uptake and overall efficiency.
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Affiliation(s)
- Jamie Leckie
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Toshifumi Yokota
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
- The Friends of Garrett Cumming Research & Muscular Dystrophy Canada HM Toupin Neurological Sciences Research, Edmonton, AB T6G 2H7, Canada
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3
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Gullulu O, Ozcelik E, Tuzlakoglu Ozturk M, Karagoz MS, Tazebay UH. A multi-faceted approach to unravel coding and non-coding gene fusions and target chimeric proteins in ataxia. J Biomol Struct Dyn 2024:1-21. [PMID: 38411012 DOI: 10.1080/07391102.2024.2321510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 02/15/2024] [Indexed: 02/28/2024]
Abstract
Ataxia represents a heterogeneous group of neurodegenerative disorders characterized by a loss of balance and coordination, often resulting from mutations in genes vital for cerebellar function and maintenance. Recent advances in genomics have identified gene fusion events as critical contributors to various cancers and neurodegenerative diseases. However, their role in ataxia pathogenesis remains largely unexplored. Our study Hdelved into this possibility by analyzing RNA sequencing data from 1443 diverse samples, including cell and mouse models, patient samples, and healthy controls. We identified 7067 novel gene fusions, potentially pivotal in disease onset. These fusions, notably in-frame, could produce chimeric proteins, disrupt gene regulation, or introduce new functions. We observed conservation of specific amino acids at fusion breakpoints and identified potential aggregate formations in fusion proteins, known to contribute to ataxia. Through AI-based protein structure prediction, we identified topological changes in three high-confidence fusion proteins-TEN1-ACOX1, PEX14-NMNAT1, and ITPR1-GRID2-which could potentially alter their functions. Subsequent virtual drug screening identified several molecules and peptides with high-affinity binding to fusion sites. Molecular dynamics simulations confirmed the stability of these protein-ligand complexes at fusion breakpoints. Additionally, we explored the role of non-coding RNA fusions as miRNA sponges. One such fusion, RP11-547P4-FLJ33910, showed strong interaction with hsa-miR-504-5p, potentially acting as its sponge. This interaction correlated with the upregulation of hsa-miR-504-5p target genes, some previously linked to ataxia. In conclusion, our study unveils new aspects of gene fusions in ataxia, suggesting their significant role in pathogenesis and opening avenues for targeted therapeutic interventions.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Omer Gullulu
- Department of Structural Biology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Emrah Ozcelik
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze, Kocaeli, Turkey
- Central Research Laboratory (GTU-MAR), Gebze Technical University, Gebze, Kocaeli, Turkey
| | - Merve Tuzlakoglu Ozturk
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze, Kocaeli, Turkey
- Central Research Laboratory (GTU-MAR), Gebze Technical University, Gebze, Kocaeli, Turkey
| | - Mustafa Safa Karagoz
- Institut für Mikrobiologie, Technische Universität Braunschweig, Braunschweig, Germany
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Uygar Halis Tazebay
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze, Kocaeli, Turkey
- Central Research Laboratory (GTU-MAR), Gebze Technical University, Gebze, Kocaeli, Turkey
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4
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Doni D, Cavion F, Bortolus M, Baschiera E, Muccioli S, Tombesi G, d'Ettorre F, Ottaviani D, Marchesan E, Leanza L, Greggio E, Ziviani E, Russo A, Bellin M, Sartori G, Carbonera D, Salviati L, Costantini P. Human frataxin, the Friedreich ataxia deficient protein, interacts with mitochondrial respiratory chain. Cell Death Dis 2023; 14:805. [PMID: 38062036 PMCID: PMC10703789 DOI: 10.1038/s41419-023-06320-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 11/14/2023] [Accepted: 11/16/2023] [Indexed: 12/18/2023]
Abstract
Friedreich ataxia (FRDA) is a rare, inherited neurodegenerative disease caused by an expanded GAA repeat in the first intron of the FXN gene, leading to transcriptional silencing and reduced expression of frataxin. Frataxin participates in the mitochondrial assembly of FeS clusters, redox cofactors of the respiratory complexes I, II and III. To date it is still unclear how frataxin deficiency culminates in the decrease of bioenergetics efficiency in FRDA patients' cells. We previously demonstrated that in healthy cells frataxin is closely attached to the mitochondrial cristae, which contain both the FeS cluster assembly machinery and the respiratory chain complexes, whereas in FRDA patients' cells with impaired respiration the residual frataxin is largely displaced in the matrix. To gain novel insights into the function of frataxin in the mitochondrial pathophysiology, and in the upstream metabolic defects leading to FRDA disease onset and progression, here we explored the potential interaction of frataxin with the FeS cluster-containing respiratory complexes I, II and III. Using healthy cells and different FRDA cellular models we found that frataxin interacts with these three respiratory complexes. Furthermore, by EPR spectroscopy, we observed that in mitochondria from FRDA patients' cells the decreased level of frataxin specifically affects the FeS cluster content of complex I. Remarkably, we also found that the frataxin-like protein Nqo15 from T. thermophilus complex I ameliorates the mitochondrial respiratory phenotype when expressed in FRDA patient's cells. Our data point to a structural and functional interaction of frataxin with complex I and open a perspective to explore therapeutic rationales for FRDA targeted to this respiratory complex.
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Affiliation(s)
- Davide Doni
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Federica Cavion
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, 35131, Padova, Italy
| | - Elisa Baschiera
- Clinical Genetics Unit, Department of Women's and Children Health, University of Padova, 35128, Padova, Italy
- Istituto di Ricerca Pediatrica (IRP) Città della Speranza, 35127, Padova, Italy
| | - Silvia Muccioli
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Giulia Tombesi
- Department of Biology, University of Padova, 35121, Padova, Italy
| | | | | | - Elena Marchesan
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Luigi Leanza
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Elisa Greggio
- Department of Biology, University of Padova, 35121, Padova, Italy
- Centro Studi per la Neurodegenerazione (CESNE), University of Padova, Padova, Italy
| | - Elena Ziviani
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Antonella Russo
- Department of Molecular Medicine, University of Padova, 35121, Padova, Italy
| | - Milena Bellin
- Department of Biology, University of Padova, 35121, Padova, Italy
- Veneto Institute of Molecular Medicine, 35129, Padova, Italy
- Department of Anatomy and Embryology, Leiden University Medical Center, 2333, ZA, Leiden, The Netherlands
| | - Geppo Sartori
- Department of Biomedical Sciences, University of Padova, 35121, Padova, Italy
| | | | - Leonardo Salviati
- Clinical Genetics Unit, Department of Women's and Children Health, University of Padova, 35128, Padova, Italy.
- Istituto di Ricerca Pediatrica (IRP) Città della Speranza, 35127, Padova, Italy.
| | - Paola Costantini
- Department of Biology, University of Padova, 35121, Padova, Italy.
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Maheshwari S, Vilema-Enríquez G, Wade-Martins R. Patient-derived iPSC models of Friedreich ataxia: a new frontier for understanding disease mechanisms and therapeutic application. Transl Neurodegener 2023; 12:45. [PMID: 37726850 PMCID: PMC10510273 DOI: 10.1186/s40035-023-00376-8] [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: 05/11/2023] [Accepted: 08/28/2023] [Indexed: 09/21/2023] Open
Abstract
Friedreich ataxia (FRDA) is a rare genetic multisystem disorder caused by a pathological GAA trinucleotide repeat expansion in the FXN gene. The numerous drawbacks of historical cellular and rodent models of FRDA have caused difficulty in performing effective mechanistic and translational studies to investigate the disease. The recent discovery and subsequent development of induced pluripotent stem cell (iPSC) technology provides an exciting platform to enable enhanced disease modelling for studies of rare genetic diseases. Utilising iPSCs, researchers have created phenotypically relevant and previously inaccessible cellular models of FRDA. These models enable studies of the molecular mechanisms underlying GAA-induced pathology, as well as providing an exciting tool for the screening and testing of novel disease-modifying therapies. This review explores how the use of iPSCs to study FRDA has developed over the past decade, as well as discussing the enormous therapeutic potentials of iPSC-derived models, their current limitations and their future direction within the field of FRDA research.
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Affiliation(s)
- Saumya Maheshwari
- Department of Physiology, Anatomy and Genetics, Kavli Institute for Nanoscience Discovery, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Gabriela Vilema-Enríquez
- Department of Physiology, Anatomy and Genetics, Kavli Institute for Nanoscience Discovery, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Richard Wade-Martins
- Department of Physiology, Anatomy and Genetics, Kavli Institute for Nanoscience Discovery, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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Khorkova O, Stahl J, Joji A, Volmar CH, Wahlestedt C. Amplifying gene expression with RNA-targeted therapeutics. Nat Rev Drug Discov 2023; 22:539-561. [PMID: 37253858 PMCID: PMC10227815 DOI: 10.1038/s41573-023-00704-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/13/2023] [Indexed: 06/01/2023]
Abstract
Many diseases are caused by insufficient expression of mutated genes and would benefit from increased expression of the corresponding protein. However, in drug development, it has been historically easier to develop drugs with inhibitory or antagonistic effects. Protein replacement and gene therapy can achieve the goal of increased protein expression but have limitations. Recent discoveries of the extensive regulatory networks formed by non-coding RNAs offer alternative targets and strategies to amplify the production of a specific protein. In addition to RNA-targeting small molecules, new nucleic acid-based therapeutic modalities that allow highly specific modulation of RNA-based regulatory networks are being developed. Such approaches can directly target the stability of mRNAs or modulate non-coding RNA-mediated regulation of transcription and translation. This Review highlights emerging RNA-targeted therapeutics for gene activation, focusing on opportunities and challenges for translation to the clinic.
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Affiliation(s)
- Olga Khorkova
- OPKO Health, Miami, FL, USA
- Center for Therapeutic Innovation, University of Miami, Miami, FL, USA
| | - Jack Stahl
- Center for Therapeutic Innovation, University of Miami, Miami, FL, USA
- Department of Psychiatry and Behavioral Sciences, University of Miami, Miami, FL, USA
| | - Aswathy Joji
- Center for Therapeutic Innovation, University of Miami, Miami, FL, USA
- Department of Chemistry, University of Miami, Miami, FL, USA
| | - Claude-Henry Volmar
- Center for Therapeutic Innovation, University of Miami, Miami, FL, USA
- Department of Psychiatry and Behavioral Sciences, University of Miami, Miami, FL, USA
| | - Claes Wahlestedt
- Center for Therapeutic Innovation, University of Miami, Miami, FL, USA.
- Department of Psychiatry and Behavioral Sciences, University of Miami, Miami, FL, USA.
- Department of Chemistry, University of Miami, Miami, FL, USA.
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Effects of combinations of gapmer antisense oligonucleotides on the target reduction. Mol Biol Rep 2023; 50:3539-3546. [PMID: 36787053 PMCID: PMC9925919 DOI: 10.1007/s11033-022-08224-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 12/20/2022] [Indexed: 02/15/2023]
Abstract
BACKGROUND The co-administration of several therapeutic oligonucleotides targeting the same transcript is a beneficial approach. It broadens the target sites for diseases associated with various mutations or splice variants. However, little is known how a combination of antisense oligonucleotides (ASOs), which is one of the major modalities of therapeutic oligonucleotides, affects the potency. In this study, we aimed to elucidate the combination-effects of ASOs and the relationship between the target sites and potency of different combinations. METHOD AND RESULTS We designed 113 ASOs targeting human superoxide dismutase 1 pre-mRNA and found 13 ASOs that had comparable silencing activity in vitro. An analysis of combination-effects on the silencing potency of 37 pairs of two ASOs on HeLa cells revealed that 29 pairs had comparable potency to that of two ASOs; on the other hand, eight pairs had reduced potency, indicating a negative impact on the activity. A reduced potency was seen in pairs targeting the same intron, exon-intron combination, or two different introns. The sequence distance of target sites was not the major determinant factor of combination-effects. In addition, a combination of three ASOs preserving the potency could be designed by avoiding two-ASO pairs, which had a reduced potency. CONCLUSIONS This study revealed that more than half of the combinations retain their potency by paring two ASOs; in contrast, some pairs had a reduced potency. This could not be predicted only by the distance between the target sites.
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Stirmlinger N, Delling JP, Pfänder S, Boeckers TM. Elevation of SHANK3 Levels by Antisense Oligonucleotides Directed Against the 3'-UTR of the Human SHANK3 mRNA. Nucleic Acid Ther 2023; 33:58-71. [PMID: 36355061 PMCID: PMC9940809 DOI: 10.1089/nat.2022.0048] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
SHANK3 is a member of the SHANK family of scaffolding proteins that localize to the postsynaptic density of excitatory synapses. Mutations within the SHANK3 gene or SHANK3 haploinsufficiency is thought to be one of the major causes for Phelan-McDermid Syndrome (PMDS) that is characterized by a broad spectrum of autism-related behavioral alterations. Several approaches have already been proposed to elevate SHANK3 protein levels in PMDS patients like transcriptional activation or inhibition of SHANK3 degradation. We undertook a systematic screening approach and tested whether defined antisense oligonucleotides (ASOs) directed against the 3' untranslated region (3'-UTR) of the human SHANK3 mRNA are suitable to elevate SHANK3 protein levels. Using human induced pluripotent stem cells (hiPSCs) and hiPSCs-derived motoneurons from controls and PMDS patients we eventually identified two 18 nucleotide ASOs (ASO 4-5.2-4 and 4-5.2-6) that were able to increase SHANK3 protein levels in vitro by about 1.3- to 1.6-fold. These findings were confirmed by co-transfection of the identified ASOs with a GFP-SHANK3-3'-UTR construct in HEK293T cells using GFP protein expression as read-out. Based on these results we propose a novel approach to elevate SHANK3 protein concentrations by 3'-UTR specific ASOs. Further research is needed to test the suitability of SHANK3-specific ASOs as pharmacological compounds also in vivo.
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Affiliation(s)
- Nadine Stirmlinger
- Institute of Anatomy and Cell Biology and Ulm University, Ulm, Germany.,International Graduate School for Molecular Medicine, Ulm University, Ulm, Germany
| | | | - Stefanie Pfänder
- Institute of Anatomy and Cell Biology and Ulm University, Ulm, Germany
| | - Tobias M. Boeckers
- Institute of Anatomy and Cell Biology and Ulm University, Ulm, Germany.,DZNE, Ulm Site, Ulm, Germany.,Address correspondence to: Tobias Boeckers, MD, Institute of Anatomy and Cell Biology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
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9
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Wang F, Calvo-Roitberg E, Rembetsy-Brown JM, Fang M, Sousa J, Kartje Z, Krishnamurthy PM, Lee J, Green M, Pai A, Watts J. G-rich motifs within phosphorothioate-based antisense oligonucleotides (ASOs) drive activation of FXN expression through indirect effects. Nucleic Acids Res 2022; 50:12657-12673. [PMID: 36511872 PMCID: PMC9825156 DOI: 10.1093/nar/gkac1108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 10/11/2022] [Accepted: 11/29/2022] [Indexed: 12/15/2022] Open
Abstract
Friedreich's ataxia is an incurable disease caused by frataxin (FXN) protein deficiency, which is mostly induced by GAA repeat expansion in intron 1 of the FXN gene. Here, we identified antisense oligonucleotides (ASOs), complementary to two regions within the first intron of FXN pre-mRNA, which could increase FXN mRNA by ∼2-fold in patient fibroblasts. The increase in FXN mRNA was confirmed by the identification of multiple overlapping FXN-activating ASOs at each region, two independent RNA quantification assays, and normalization by multiple housekeeping genes. Experiments on cells with the ASO-binding sites deleted indicate that the ASO-induced FXN activation was driven by indirect effects. RNA sequencing analyses showed that the two ASOs induced similar transcriptome-wide changes, which did not resemble the transcriptome of wild-type cells. This RNA-seq analysis did not identify directly base-paired off-target genes shared across ASOs. Mismatch studies identified two guanosine-rich motifs (CCGG and G4) within the ASOs that were required for FXN activation. The phosphorodiamidate morpholino oligomer analogs of our ASOs did not activate FXN, pointing to a PS-backbone-mediated effect. Our study demonstrates the importance of multiple, detailed control experiments and target validation in oligonucleotide studies employing novel mechanisms such as gene activation.
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Affiliation(s)
- Feng Wang
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Ezequiel Calvo-Roitberg
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Julia M Rembetsy-Brown
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Minggang Fang
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Jacquelyn Sousa
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Zachary J Kartje
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | | | - Jonathan Lee
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Michael R Green
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Athma A Pai
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Jonathan K Watts
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
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10
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Masnovo C, Lobo AF, Mirkin SM. Replication dependent and independent mechanisms of GAA repeat instability. DNA Repair (Amst) 2022; 118:103385. [PMID: 35952488 PMCID: PMC9675320 DOI: 10.1016/j.dnarep.2022.103385] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/28/2022] [Accepted: 07/30/2022] [Indexed: 11/20/2022]
Abstract
Trinucleotide repeat instability is a driver of human disease. Large expansions of (GAA)n repeats in the first intron of the FXN gene are the cause Friedreich's ataxia (FRDA), a progressive degenerative disorder which cannot yet be prevented or treated. (GAA)n repeat instability arises during both replication-dependent processes, such as cell division and intergenerational transmission, as well as in terminally differentiated somatic tissues. Here, we provide a brief historical overview on the discovery of (GAA)n repeat expansions and their association to FRDA, followed by recent advances in the identification of triplex H-DNA formation and replication fork stalling. The main body of this review focuses on the last decade of progress in understanding the mechanism of (GAA)n repeat instability during DNA replication and/or DNA repair. We propose that the discovery of additional mechanisms of (GAA)n repeat instability can be achieved via both comparative approaches to other repeat expansion diseases and genome-wide association studies. Finally, we discuss the advances towards FRDA prevention or amelioration that specifically target (GAA)n repeat expansions.
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Affiliation(s)
- Chiara Masnovo
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Ayesha F Lobo
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02155, USA.
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