1
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Cadden G, Wilken S, Magennis S. A single CAA interrupt in a DNA three-way junction containing a CAG repeat hairpin results in parity-dependent trapping. Nucleic Acids Res 2024; 52:9317-9327. [PMID: 39041420 PMCID: PMC11347167 DOI: 10.1093/nar/gkae644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 07/04/2024] [Accepted: 07/14/2024] [Indexed: 07/24/2024] Open
Abstract
An increasing number of human disorders are attributed to genomic expansions of short tandem repeats (STRs). Secondary DNA structures formed by STRs are believed to play an important role in expansion, while the presence of nucleotide interruptions within the pure repeat sequence is known to delay the onset and progression of disease. We have used two single-molecule fluorescence techniques to analyse the structure and dynamics of DNA three-way junctions (3WJs) containing CAG repeat hairpin slipouts, with and without a single CAA interrupt. For a 3WJ with a (CAG)10 slipout, the CAA interrupt is preferentially located in the hairpin loop, and the branch migration dynamics are 4-fold slower than for the 3WJ with a pure (CAG)10, and 3-fold slower than a 3WJ with a pure (CAG)40 repeat. The (CAG)11 3WJ with CAA interrupt adopts a conformation that places the interrupt in or near the hairpin loop, with similar dynamics to the pure (CAG)10 and (CAG)11 3WJs. We have shown that changing a single nucleotide (G to A) in a pure repeat can have a large impact on 3WJ structure and dynamics, which may be important for the protective role of interrupts in repeat expansion diseases.
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Affiliation(s)
- Gillian M Cadden
- School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow G12 8QQ, UK
| | - Svea J Wilken
- School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow G12 8QQ, UK
| | - Steven W Magennis
- School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow G12 8QQ, UK
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2
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Yao YM, Miodownik I, O'Hagan MP, Jbara M, Afek A. Deciphering the dynamic code: DNA recognition by transcription factors in the ever-changing genome. Transcription 2024:1-25. [PMID: 39033307 DOI: 10.1080/21541264.2024.2379161] [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: 03/15/2024] [Accepted: 07/03/2024] [Indexed: 07/23/2024] Open
Abstract
Transcription factors (TFs) intricately navigate the vast genomic landscape to locate and bind specific DNA sequences for the regulation of gene expression programs. These interactions occur within a dynamic cellular environment, where both DNA and TF proteins experience continual chemical and structural perturbations, including epigenetic modifications, DNA damage, mechanical stress, and post-translational modifications (PTMs). While many of these factors impact TF-DNA binding interactions, understanding their effects remains challenging and incomplete. This review explores the existing literature on these dynamic changes and their potential impact on TF-DNA interactions.
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Affiliation(s)
- Yumi Minyi Yao
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Irina Miodownik
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Michael P O'Hagan
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Muhammad Jbara
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ariel Afek
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
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3
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Wang N, Zhang S, Langfelder P, Ramanathan L, Plascencia M, Gao F, Vaca R, Gu X, Deng L, Dionisio LE, Prasad BC, Vogt T, Horvath S, Aaronson JS, Rosinski J, Yang XW. Msh3 and Pms1 Set Neuronal CAG-repeat Migration Rate to Drive Selective Striatal and Cortical Pathogenesis in HD Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.09.602815. [PMID: 39026894 PMCID: PMC11257559 DOI: 10.1101/2024.07.09.602815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Modifiers of Huntington's disease (HD) include mismatch repair (MMR) genes; however, their underlying disease-altering mechanisms remain unresolved. Knockout (KO) alleles for 9 HD GWAS modifiers/MMR genes were crossed to the Q140 Huntingtin (mHtt) knock-in mice to probe such mechanisms. Four KO mice strongly ( Msh3 and Pms1 ) or moderately ( Msh2 and Mlh1 ) rescue a triad of adult-onset, striatal medium-spiny-neuron (MSN)-selective phenotypes: somatic Htt DNA CAG-repeat expansion, transcriptionopathy, and mHtt protein aggregation. Comparatively, Q140 cortex also exhibits an analogous, but later-onset, pathogenic triad that is Msh3 -dependent. Remarkably, Q140/homozygous Msh3-KO lacks visible mHtt aggregates in the brain, even at advanced ages (20-months). Moreover, Msh3 -deficiency prevents striatal synaptic marker loss, astrogliosis, and locomotor impairment in HD mice. Purified Q140 MSN nuclei exhibit highly linear age-dependent mHtt DNA repeat expansion (i.e. repeat migration), with modal-CAG increasing at +8.8 repeats/month (R 2 =0.98). This linear rate is reduced to 2.3 and 0.3 repeats/month in Q140 with Msh3 heterozygous and homozygous alleles, respectively. Our study defines somatic Htt CAG-repeat thresholds below which there are no detectable mHtt nuclear or neuropil aggregates. Mild transcriptionopathy can still occur in Q140 mice with stabilized Htt 140-CAG repeats, but the majority of transcriptomic changes are due to somatic repeat expansion. Our analysis reveals 479 genes with expression levels highly correlated with modal-CAG length in MSNs. Thus, our study mechanistically connects HD GWAS genes to selective neuronal vulnerability in HD, in which Msh3 and Pms1 set the linear rate of neuronal mHtt CAG-repeat migration to drive repeat-length dependent pathogenesis; and provides a preclinical platform for targeting these genes for HD suppression across brain regions. One Sentence Summary Msh3 and Pms1 are genetic drivers of sequential striatal and cortical pathogenesis in Q140 mice by mediating selective CAG-repeat migration in HD vulnerable neurons.
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4
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Stanisławska-Sachadyn A, Krzemiński M, Zielonka D, Krygier M, Ziętkiewicz E, Sławek J, Limon J. Sex contribution to average age at onset of Huntington's disease depends on the number of (CAG) n repeats. Sci Rep 2024; 14:15729. [PMID: 38977715 PMCID: PMC11231309 DOI: 10.1038/s41598-024-64105-5] [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: 12/22/2023] [Accepted: 06/05/2024] [Indexed: 07/10/2024] Open
Abstract
Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by the extension of the CAG repeats in exon 1 of the HTT gene and is transmitted in a dominant manner. The present study aimed to assess whether patients' sex, in the context of mutated and normal allele length, contributes to age on onset (AO) of HD. The study population comprised a large cohort of 3723 HD patients from the European Huntington's Disease Network's REGISTRY database collected at 160 sites across 17 European countries and in one location outside Europe. The data were analyzed using regression models and factorial analysis of variance (ANOVA) considering both mutated allele length and sex as predictors of patients' AO. AO, as described by the rater's estimate, was found to be later in affected women than in men across the whole population. This difference was most pronounced in a subgroup of 1273 patients with relatively short variants of the mutated allele (40-45 CAG repeats) and normal alleles in a higher half of length distribution-namely, more than 17 CAG repeats; however, it was also observed in each group. Our results presented in this observational study point to sex-related differences in AO, most pronounced in the presence of the short mutated and long normal allele, which may add to understanding the dynamics of AO in Huntington's Disease.Trial registration: ClinicalTrials.gov identifier NCT01590589.
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Affiliation(s)
- Anna Stanisławska-Sachadyn
- Department of Biotechnology and Microbiology, Gdańsk University of Technology, 80-233, Gdańsk, Poland.
- Department of Biology and Medical Genetics, Medical University of Gdańsk, 80-211, Gdańsk, Poland.
- BioTechMed Center, Gdańsk University of Technology, Narutowicza 11/12, 80-233, Gdańsk, Poland.
| | - Michał Krzemiński
- Institute of Applied Mathematics , Gdańsk University of Technology, 80-233, Gdańsk, Poland
| | - Daniel Zielonka
- Department of Public Health, Poznań University of Medical Sciences, 60-812, Poznan, Poland
| | - Magdalena Krygier
- Department of Developmental Neurology, Medical University of Gdansk, 80-952, Gdańsk, Poland
| | - Ewa Ziętkiewicz
- Institute of Human Genetics, Polish Academy of Sciences, 60-479, Poznan, Poland
| | - Jarosław Sławek
- Department of Neurology, St. Adalbert Hospital, Copernicus PL, 80-462,, Gdańsk, Poland
- Department of Neurological and Psychiatric Nursing, Faculty of Health Sciences, Medical University of Gdańsk, 80-211, Gdańsk, Poland
| | - Janusz Limon
- Department of Medical Ethics, Medical University of Gdańsk, 80-211, Gdańsk, Poland
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5
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Pengo M, Squitieri F. Beyond CAG Repeats: The Multifaceted Role of Genetics in Huntington Disease. Genes (Basel) 2024; 15:807. [PMID: 38927742 PMCID: PMC11203031 DOI: 10.3390/genes15060807] [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: 05/01/2024] [Revised: 06/11/2024] [Accepted: 06/18/2024] [Indexed: 06/28/2024] Open
Abstract
Huntington disease (HD) is a dominantly inherited neurodegenerative disorder caused by a CAG expansion on the huntingtin (HTT) gene and is characterized by progressive motor, cognitive, and neuropsychiatric decline. Recently, new genetic factors besides CAG repeats have been implicated in the disease pathogenesis. Most genetic modifiers are involved in DNA repair pathways and, as the cause of the loss of CAA interruption in the HTT gene, they exert their main influence through somatic expansion. However, this mechanism might not be the only driver of HD pathogenesis, and future studies are warranted in this field. The aim of the present review is to dissect the many faces of genetics in HD pathogenesis, from cis- and trans-acting genetic modifiers to RNA toxicity, mitochondrial DNA mutations, and epigenetics factors. Exploring genetic modifiers of HD onset and progression appears crucial to elucidate not only disease pathogenesis, but also to improve disease prediction and prevention, develop biomarkers of disease progression and response to therapies, and recognize new therapeutic opportunities. Since the same genetic mechanisms are also described in other repeat expansion diseases, their implications might encompass the whole spectrum of these disorders.
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Affiliation(s)
- Marta Pengo
- Department of Molecular and Translational Medicine, University of Brescia, 25121 Brescia, Italy;
| | - Ferdinando Squitieri
- Centre for Neurological Rare Diseases (CMNR), Fondazione Lega Italiana Ricerca Huntington (LIRH), 00161 Rome, Italy
- Huntington and Rare Diseases Unit, IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy
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6
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Hayward B, Kumari D, Santra S, van Karnebeek CDM, van Kuilenburg ABP, Usdin K. All three MutL complexes are required for repeat expansion in a human stem cell model of CAG-repeat expansion mediated glutaminase deficiency. Sci Rep 2024; 14:13772. [PMID: 38877099 PMCID: PMC11178883 DOI: 10.1038/s41598-024-64480-z] [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: 01/09/2024] [Accepted: 06/10/2024] [Indexed: 06/16/2024] Open
Abstract
The Repeat Expansion Diseases (REDs) arise from the expansion of a disease-specific short tandem repeat (STR). Different REDs differ with respect to the repeat involved, the cells that are most expansion prone and the extent of expansion. Furthermore, whether these diseases share a common expansion mechanism is unclear. To date, expansion has only been studied in a limited number of REDs. Here we report the first studies of the expansion mechanism in induced pluripotent stem cells derived from a patient with a form of the glutaminase deficiency disorder known as Global Developmental Delay, Progressive Ataxia, And Elevated Glutamine (GDPAG; OMIM# 618412) caused by the expansion of a CAG-STR in the 5' UTR of the glutaminase (GLS) gene. We show that alleles with as few as ~ 120 repeats show detectable expansions in culture despite relatively low levels of R-loops formed at this locus. Additionally, using a CRISPR-Cas9 knockout approach we show that PMS2 and MLH3, the constituents of MutLα and MutLγ, the 2 mammalian MutL complexes known to be involved in mismatch repair (MMR), are essential for expansion. Furthermore, PMS1, a component of a less well understood MutL complex, MutLβ, is also important, if not essential, for repeat expansion in these cells. Our results provide insights into the factors important for expansion and lend weight to the idea that, despite some differences, the same mechanism is responsible for expansion in many, if not all, REDs.
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Affiliation(s)
- Bruce Hayward
- Section On Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Daman Kumari
- Section On Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Saikat Santra
- Birmingham Women's and Children's NHS Foundation Trust, Birmingham, B15 2TG, UK
| | - Clara D M van Karnebeek
- Emma Center for Personalized Medicine, Departments of Pediatrics and Human Genetics, Amsterdam Gastro-Enterology Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
- United for Metabolic Diseases, Amsterdam, The Netherlands
| | - André B P van Kuilenburg
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam, The Netherlands
| | - Karen Usdin
- Section On Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA.
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7
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Ferguson R, Goold R, Coupland L, Flower M, Tabrizi SJ. Therapeutic validation of MMR-associated genetic modifiers in a human ex vivo model of Huntington disease. Am J Hum Genet 2024; 111:1165-1183. [PMID: 38749429 PMCID: PMC11179424 DOI: 10.1016/j.ajhg.2024.04.015] [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: 11/30/2023] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 06/09/2024] Open
Abstract
The pathological huntingtin (HTT) trinucleotide repeat underlying Huntington disease (HD) continues to expand throughout life. Repeat length correlates both with earlier age at onset (AaO) and faster progression, making slowing its expansion an attractive therapeutic approach. Genome-wide association studies have identified candidate variants associated with altered AaO and progression, with many found in DNA mismatch repair (MMR)-associated genes. We examine whether lowering expression of these genes affects the rate of repeat expansion in human ex vivo models using HD iPSCs and HD iPSC-derived striatal medium spiny neuron-enriched cultures. We have generated a stable CRISPR interference HD iPSC line in which we can specifically and efficiently lower gene expression from a donor carrying over 125 CAG repeats. Lowering expression of each member of the MMR complexes MutS (MSH2, MSH3, and MSH6), MutL (MLH1, PMS1, PMS2, and MLH3), and LIG1 resulted in characteristic MMR deficiencies. Reduced MSH2, MSH3, and MLH1 slowed repeat expansion to the largest degree, while lowering either PMS1, PMS2, or MLH3 slowed it to a lesser degree. These effects were recapitulated in iPSC-derived striatal cultures where MutL factor expression was lowered. CRISPRi-mediated lowering of key MMR factor expression to levels feasibly achievable by current therapeutic approaches was able to effectively slow the expansion of the HTT CAG tract. We highlight members of the MutL family as potential targets to slow pathogenic repeat expansion with the aim to delay onset and progression of HD and potentially other repeat expansion disorders exhibiting somatic instability.
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Affiliation(s)
- Ross Ferguson
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Dementia Research Institute at UCL, London WC1N 3BG, UK
| | - Robert Goold
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Dementia Research Institute at UCL, London WC1N 3BG, UK
| | - Lucy Coupland
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Dementia Research Institute at UCL, London WC1N 3BG, UK
| | - Michael Flower
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Dementia Research Institute at UCL, London WC1N 3BG, UK
| | - Sarah J Tabrizi
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Dementia Research Institute at UCL, London WC1N 3BG, UK.
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8
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Zhang Y, Liu X, Li Z, Li H, Miao Z, Wan B, Xu X. Advances on the Mechanisms and Therapeutic Strategies in Non-coding CGG Repeat Expansion Diseases. Mol Neurobiol 2024:10.1007/s12035-024-04239-9. [PMID: 38780719 DOI: 10.1007/s12035-024-04239-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 05/02/2024] [Indexed: 05/25/2024]
Abstract
Non-coding CGG repeat expansions within the 5' untranslated region are implicated in a range of neurological disorders, including fragile X-associated tremor/ataxia syndrome, oculopharyngeal myopathy with leukodystrophy, and oculopharyngodistal myopathy. This review outlined the general characteristics of diseases associated with non-coding CGG repeat expansions, detailing their clinical manifestations and neuroimaging patterns, which often overlap and indicate shared pathophysiological traits. We summarized the underlying molecular mechanisms of these disorders, providing new insights into the roles that DNA, RNA, and toxic proteins play. Understanding these mechanisms is crucial for the development of targeted therapeutic strategies. These strategies include a range of approaches, such as antisense oligonucleotides, RNA interference, genomic DNA editing, small molecule interventions, and other treatments aimed at correcting the dysregulated processes inherent in these disorders. A deeper understanding of the shared mechanisms among non-coding CGG repeat expansion disorders may hold the potential to catalyze the development of innovative therapies, ultimately offering relief to individuals grappling with these debilitating neurological conditions.
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Affiliation(s)
- Yutong Zhang
- Departments of Neurology, The First Affiliated Hospital of Soochow University, Suzhou City, China
| | - Xuan Liu
- Departments of Neurology, The First Affiliated Hospital of Soochow University, Suzhou City, China
| | - Zeheng Li
- Departments of Neurology, The First Affiliated Hospital of Soochow University, Suzhou City, China
| | - Hao Li
- Departments of Neurology, The First Affiliated Hospital of Soochow University, Suzhou City, China
- Department of Neurology, The Fourth Affiliated Hospital of Soochow University, Suzhou, 215124, China
| | - Zhigang Miao
- The Institute of Neuroscience, Soochow University, Suzhou City, China
| | - Bo Wan
- The Institute of Neuroscience, Soochow University, Suzhou City, China
| | - Xingshun Xu
- Departments of Neurology, The First Affiliated Hospital of Soochow University, Suzhou City, China.
- The Institute of Neuroscience, Soochow University, Suzhou City, China.
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou, 215000, China.
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9
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Provasek VE, Bacolla A, Rangaswamy S, Mitra J, Kodavati M, Yusuf IO, Malojirao VH, Vasquez V, Britz GW, Li GM, Xu Z, Mitra S, Garruto RM, Tainer JA, Hegde ML. RNA/DNA Binding Protein TDP43 Regulates DNA Mismatch Repair Genes with Implications for Genome Stability. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.16.594552. [PMID: 38798341 PMCID: PMC11118483 DOI: 10.1101/2024.05.16.594552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
TDP43 is an RNA/DNA binding protein increasingly recognized for its role in neurodegenerative conditions including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). As characterized by its aberrant nuclear export and cytoplasmic aggregation, TDP43 proteinopathy is a hallmark feature in over 95% of ALS/FTD cases, leading to the formation of detrimental cytosolic aggregates and a reduction in nuclear functionality within neurons. Building on our prior work linking TDP43 proteinopathy to the accumulation of DNA double-strand breaks (DSBs) in neurons, the present investigation uncovers a novel regulatory relationship between TDP43 and DNA mismatch repair (MMR) gene expressions. Here, we show that TDP43 depletion or overexpression directly affects the expression of key MMR genes. Alterations include MLH1, MSH2, MSH3, MSH6, and PMS2 levels across various primary cell lines, independent of their proliferative status. Our results specifically establish that TDP43 selectively influences the expression of MLH1 and MSH6 by influencing their alternative transcript splicing patterns and stability. We furthermore find aberrant MMR gene expression is linked to TDP43 proteinopathy in two distinct ALS mouse models and post-mortem brain and spinal cord tissues of ALS patients. Notably, MMR depletion resulted in the partial rescue of TDP43 proteinopathy-induced DNA damage and signaling. Moreover, bioinformatics analysis of the TCGA cancer database reveals significant associations between TDP43 expression, MMR gene expression, and mutational burden across multiple cancers. Collectively, our findings implicate TDP43 as a critical regulator of the MMR pathway and unveil its broad impact on the etiology of both neurodegenerative and neoplastic pathologies.
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Affiliation(s)
- Vincent E Provasek
- Division of DNA Repair Research within the Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, USA
- School of Medicine, Texas A&M University, College Station, TX 77843, USA
| | - Albino Bacolla
- Department of Molecular and Cellular Oncology, Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Suganya Rangaswamy
- Division of DNA Repair Research within the Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Joy Mitra
- Division of DNA Repair Research within the Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Manohar Kodavati
- Division of DNA Repair Research within the Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Issa O Yusuf
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, 01655, USA
| | - Vikas H Malojirao
- Division of DNA Repair Research within the Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Velmarini Vasquez
- Division of DNA Repair Research within the Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Gavin W Britz
- Division of DNA Repair Research within the Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Neurosurgery and Department of Neuroscience, Weill Cornell Medical College, New York, NY 10065, USA
| | - Guo-Min Li
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Zuoshang Xu
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, 01655, USA
| | - Sankar Mitra
- Division of DNA Repair Research within the Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, USA
| | - Ralph M Garruto
- Department of Biological Sciences, Binghamton University, State University of New York, Binghamton, NY 13902
| | - John A Tainer
- Department of Molecular and Cellular Oncology, Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Muralidhar L Hegde
- Division of DNA Repair Research within the Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Neuroscience, Weill Cornell Medical College, New York, NY 10065, USA
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10
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Aldous SG, Smith EJ, Landles C, Osborne GF, Cañibano-Pico M, Nita IM, Phillips J, Zhang Y, Jin B, Hirst MB, Benn CL, Bond BC, Edelmann W, Greene JR, Bates GP. A CAG repeat threshold for therapeutics targeting somatic instability in Huntington's disease. Brain 2024; 147:1784-1798. [PMID: 38387080 PMCID: PMC11068328 DOI: 10.1093/brain/awae063] [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: 12/01/2023] [Accepted: 02/07/2024] [Indexed: 02/24/2024] Open
Abstract
The Huntington's disease mutation is a CAG repeat expansion in the huntingtin gene that results in an expanded polyglutamine tract in the huntingtin protein. The CAG repeat is unstable and expansions of hundreds of CAGs have been detected in Huntington's disease post-mortem brains. The age of disease onset can be predicted partially from the length of the CAG repeat as measured in blood. Onset age is also determined by genetic modifiers, which in six cases involve variation in DNA mismatch repair pathways genes. Knocking-out specific mismatch repair genes in mouse models of Huntington's disease prevents somatic CAG repeat expansion. Taken together, these results have led to the hypothesis that somatic CAG repeat expansion in Huntington's disease brains is required for pathogenesis. Therefore, the pathogenic repeat threshold in brain is longer than (CAG)40, as measured in blood, and is currently unknown. The mismatch repair gene MSH3 has become a major focus for therapeutic development, as unlike other mismatch repair genes, nullizygosity for MSH3 does not cause malignancies associated with mismatch repair deficiency. Potential treatments targeting MSH3 currently under development include gene therapy, biologics and small molecules, which will be assessed for efficacy in mouse models of Huntington's disease. The zQ175 knock-in model carries a mutation of approximately (CAG)185 and develops early molecular and pathological phenotypes that have been extensively characterized. Therefore, we crossed the mutant huntingtin allele onto heterozygous and homozygous Msh3 knockout backgrounds to determine the maximum benefit of targeting Msh3 in this model. Ablation of Msh3 prevented somatic expansion throughout the brain and periphery, and reduction of Msh3 by 50% decreased the rate of expansion. This had no effect on the deposition of huntingtin aggregation in the nuclei of striatal neurons, nor on the dysregulated striatal transcriptional profile. This contrasts with ablating Msh3 in knock-in models with shorter CAG repeat expansions. Therefore, further expansion of a (CAG)185 repeat in striatal neurons does not accelerate the onset of molecular and neuropathological phenotypes. It is striking that highly expanded CAG repeats of a similar size in humans cause disease onset before 2 years of age, indicating that somatic CAG repeat expansion in the brain is not required for pathogenesis. Given that the trajectory for somatic CAG expansion in the brains of Huntington's disease mutation carriers is unknown, our study underlines the importance of administering treatments targeting somatic instability as early as possible.
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Affiliation(s)
- Sarah G Aldous
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Edward J Smith
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Christian Landles
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Georgina F Osborne
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Maria Cañibano-Pico
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Iulia M Nita
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Jemima Phillips
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Yongwei Zhang
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Bo Jin
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY 10461, USA
| | | | - Caroline L Benn
- LoQus23 Therapeutics, Riverside, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - Brian C Bond
- Prism Training and Consultancy Limited, St John's Innovation Centre, Cambridge, CB4 0WS, UK
| | - Winfried Edelmann
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY 10461, USA
| | | | - Gillian P Bates
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
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11
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Kacher R, Lejeune FX, David I, Boluda S, Coarelli G, Leclere-Turbant S, Heinzmann A, Marelli C, Charles P, Goizet C, Kabir N, Hilab R, Jornea L, Six J, Dommergues M, Fauret AL, Brice A, Humbert S, Durr A. CAG repeat mosaicism is gene specific in spinocerebellar ataxias. Am J Hum Genet 2024; 111:913-926. [PMID: 38626762 PMCID: PMC11080609 DOI: 10.1016/j.ajhg.2024.03.015] [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: 09/28/2023] [Revised: 03/25/2024] [Accepted: 03/25/2024] [Indexed: 04/18/2024] Open
Abstract
Expanded CAG repeats in coding regions of different genes are the most common cause of dominantly inherited spinocerebellar ataxias (SCAs). These repeats are unstable through the germline, and larger repeats lead to earlier onset. We measured somatic expansion in blood samples collected from 30 SCA1, 50 SCA2, 74 SCA3, and 30 SCA7 individuals over a mean interval of 8.5 years, along with postmortem tissues and fetal tissues from SCA1, SCA3, and SCA7 individuals to examine somatic expansion at different stages of life. We showed that somatic mosaicism in the blood increases over time. Expansion levels are significantly different among SCAs and correlate with CAG repeat lengths. The level of expansion is greater in individuals with SCA7 who manifest disease compared to that of those who do not yet display symptoms. Brain tissues from SCA individuals have larger expansions compared to the blood. The cerebellum has the lowest mosaicism among the studied brain regions, along with a high expression of ATXNs and DNA repair genes. This was the opposite in cortices, with the highest mosaicism and lower expression of ATXNs and DNA repair genes. Fetal cortices did not show repeat instability. This study shows that CAG repeats are increasingly unstable during life in the blood and the brain of SCA individuals, with gene- and tissue-specific patterns.
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Affiliation(s)
- Radhia Kacher
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - François-Xavier Lejeune
- Sorbonne Université, Paris Brain Institute's Data Analysis Core Facility, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Isabelle David
- Sorbonne Université, Department of Genetics, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Susana Boluda
- Sorbonne Université, Department of Neuropathology Raymond Escourolle, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Giulia Coarelli
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Sabrina Leclere-Turbant
- Sorbonne Université, Biobank Neuro-CEB Biological Resource Platform, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Anna Heinzmann
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Cecilia Marelli
- MMDN, Université Montpellier, EPHE, INSERM, Montpellier, France; Expert Center for Neurogenetic Diseases, CHU, Montpellier, France
| | - Perrine Charles
- Sorbonne Université, Department of Genetics, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Cyril Goizet
- Université Bordeaux, Equipe « Neurogénétique Translationnelle - NRGEN », INCIA CNRS UMR5287 Université Bordeaux and Centre de Reference Maladies Rares « Neurogénétique », Service de Génétique Médicale, Bordeaux University Hospital (CHU Bordeaux), Bordeaux, France
| | - Nisha Kabir
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Rania Hilab
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Ludmila Jornea
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Julie Six
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Marc Dommergues
- Sorbonne Université, Service de Gynécologie Obstetrique, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Anne-Laure Fauret
- Sorbonne Université, Department of Genetics, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Alexis Brice
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Sandrine Humbert
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France
| | - Alexandra Durr
- Sorbonne Université, Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hopital de la Pitié-Salpêtrière, Paris, France.
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12
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McLean ZL, Gao D, Correia K, Roy JCL, Shibata S, Farnum IN, Valdepenas-Mellor Z, Kovalenko M, Rapuru M, Morini E, Ruliera J, Gillis T, Lucente D, Kleinstiver BP, Lee JM, MacDonald ME, Wheeler VC, Mouro Pinto R, Gusella JF. Splice modulators target PMS1 to reduce somatic expansion of the Huntington's disease-associated CAG repeat. Nat Commun 2024; 15:3182. [PMID: 38609352 PMCID: PMC11015039 DOI: 10.1038/s41467-024-47485-0] [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: 07/24/2023] [Accepted: 03/30/2024] [Indexed: 04/14/2024] Open
Abstract
Huntington's disease (HD) is a dominant neurological disorder caused by an expanded HTT exon 1 CAG repeat that lengthens huntingtin's polyglutamine tract. Lowering mutant huntingtin has been proposed for treating HD, but genetic modifiers implicate somatic CAG repeat expansion as the driver of onset. We find that branaplam and risdiplam, small molecule splice modulators that lower huntingtin by promoting HTT pseudoexon inclusion, also decrease expansion of an unstable HTT exon 1 CAG repeat in an engineered cell model. Targeted CRISPR-Cas9 editing shows this effect is not due to huntingtin lowering, pointing instead to pseudoexon inclusion in PMS1. Homozygous but not heterozygous inactivation of PMS1 also reduces CAG repeat expansion, supporting PMS1 as a genetic modifier of HD and a potential target for therapeutic intervention. Although splice modulation provides one strategy, genome-wide transcriptomics also emphasize consideration of cell-type specific effects and polymorphic variation at both target and off-target sites.
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Affiliation(s)
- Zachariah L McLean
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Dadi Gao
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Kevin Correia
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Jennie C L Roy
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
| | - Shota Shibata
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Iris N Farnum
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Zoe Valdepenas-Mellor
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Marina Kovalenko
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Manasa Rapuru
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Elisabetta Morini
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
| | - Jayla Ruliera
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Tammy Gillis
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Diane Lucente
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Benjamin P Kleinstiver
- Center for Genomic Medicine and Department of Pathology, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Pathology, Harvard Medical School, Boston, MA, 02115, USA
| | - Jong-Min Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Marcy E MacDonald
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Vanessa C Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - Ricardo Mouro Pinto
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA, 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - James F Gusella
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA.
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA.
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
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13
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Skeens A, Siriwardhana C, Massinople SE, Wunder MM, Ellis ZL, Keith KM, Girman T, Frey SL, Legleiter J. The polyglutamine domain is the primary driver of seeding in huntingtin aggregation. PLoS One 2024; 19:e0298323. [PMID: 38483973 PMCID: PMC10939245 DOI: 10.1371/journal.pone.0298323] [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: 04/27/2023] [Accepted: 01/22/2024] [Indexed: 03/17/2024] Open
Abstract
Huntington's Disease (HD) is a fatal, neurodegenerative disease caused by aggregation of the huntingtin protein (htt) with an expanded polyglutamine (polyQ) domain into amyloid fibrils. Htt aggregation is modified by flanking sequences surrounding the polyQ domain as well as the binding of htt to lipid membranes. Upon fibrillization, htt fibrils are able to template the aggregation of monomers into fibrils in a phenomenon known as seeding, and this process appears to play a critical role in cell-to-cell spread of HD. Here, exposure of C. elegans expressing a nonpathogenic N-terminal htt fragment (15-repeat glutamine residues) to preformed htt-exon1 fibrils induced inclusion formation and resulted in decreased viability in a dose dependent manner, demonstrating that seeding can induce toxic aggregation of nonpathogenic forms of htt. To better understand this seeding process, the impact of flanking sequences adjacent to the polyQ stretch, polyQ length, and the presence of model lipid membranes on htt seeding was investigated. Htt seeding readily occurred across polyQ lengths and was independent of flanking sequence, suggesting that the structured polyQ domain within fibrils is the key contributor to the seeding phenomenon. However, the addition of lipid vesicles modified seeding efficiency in a manner suggesting that seeding primarily occurs in bulk solution and not at the membrane interface. In addition, fibrils formed in the presence of lipid membranes displayed similar seeding efficiencies. Collectively, this suggests that the polyQ domain that forms the amyloid fibril core is the main driver of seeding in htt aggregation.
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Affiliation(s)
- Adam Skeens
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
| | - Chathuranga Siriwardhana
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
| | - Sophia E. Massinople
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
| | - Michelle M. Wunder
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
| | - Zachary L. Ellis
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
| | - Kaitlyn M. Keith
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
| | - Tyler Girman
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
| | - Shelli L. Frey
- The Department of Chemistry, Gettysburg College, Gettysburg, Pennsylvania, United States of America
| | - Justin Legleiter
- The C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia, United States of America
- Rockefeller Neurosciences Institutes, West Virginia University, Morgantown, West Virginia, United States of America
- Department of Neuroscience, West Virginia University, Morgantown, West Virginia, United States of America
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14
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Dalene Skarping K, Arning L, Petersén Å, Nguyen HP, Gebre-Medhin S. Attenuated huntingtin gene CAG nucleotide repeat size in individuals with Lynch syndrome. Sci Rep 2024; 14:4300. [PMID: 38383663 PMCID: PMC10881568 DOI: 10.1038/s41598-024-54277-5] [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: 09/14/2023] [Accepted: 02/10/2024] [Indexed: 02/23/2024] Open
Abstract
DNA mismatch repair (MMR) is thought to contribute to the onset and progression of Huntington disease (HD) by promoting somatic expansion of the pathogenic CAG nucleotide repeat in the huntingtin gene (HTT). Here we have studied constitutional HTT CAG repeat size in two cohorts of individuals with Lynch syndrome (LS) carrying heterozygous loss-of-function variants in the MMR genes MLH1 (n = 12/60; Lund cohort/Bochum cohort, respectively), MSH2 (n = 15/88), MSH6 (n = 21/23), and controls (n = 19/559). The sum of CAG repeats for both HTT alleles in each individual was calculated due to unknown segregation with the LS allele. In the larger Bochum cohort, the sum of CAG repeats was lower in the MLH1 subgroup compared to controls (MLH1 35.40 CAG repeats ± 3.6 vs. controls 36.89 CAG repeats ± 4.5; p = 0.014). All LS genetic subgroups in the Bochum cohort displayed lower frequencies of unstable HTT intermediate alleles and lower HTT somatic CAG repeat expansion index values compared to controls. Collectively, our results indicate that MMR gene haploinsufficiency could have a restraining impact on constitutional HTT CAG repeat size and support the notion that the MMR pathway is a driver of nucleotide repeat expansion diseases.
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Affiliation(s)
- Karin Dalene Skarping
- Division of Clinical Genetics, Department of Laboratory Medicine, Lund University, Lund, Sweden
- Department of Clinical Genetics and Pathology, Office for Medical Service, 221 85, Lund, Sweden
- Translational Neuroendocrine Research Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Larissa Arning
- Department of Human Genetics, Faculty of Medicine, Ruhr University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Åsa Petersén
- Translational Neuroendocrine Research Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Huu Phuc Nguyen
- Department of Human Genetics, Faculty of Medicine, Ruhr University Bochum, Universitätsstr. 150, 44801, Bochum, Germany.
| | - Samuel Gebre-Medhin
- Division of Clinical Genetics, Department of Laboratory Medicine, Lund University, Lund, Sweden.
- Department of Clinical Genetics and Pathology, Office for Medical Service, 221 85, Lund, Sweden.
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15
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Waters KL, Spratt DE. New Discoveries on Protein Recruitment and Regulation during the Early Stages of the DNA Damage Response Pathways. Int J Mol Sci 2024; 25:1676. [PMID: 38338953 PMCID: PMC10855619 DOI: 10.3390/ijms25031676] [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: 12/19/2023] [Revised: 01/26/2024] [Accepted: 01/28/2024] [Indexed: 02/12/2024] Open
Abstract
Maintaining genomic stability and properly repairing damaged DNA is essential to staying healthy and preserving cellular homeostasis. The five major pathways involved in repairing eukaryotic DNA include base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), non-homologous end joining (NHEJ), and homologous recombination (HR). When these pathways do not properly repair damaged DNA, genomic stability is compromised and can contribute to diseases such as cancer. It is essential that the causes of DNA damage and the consequent repair pathways are fully understood, yet the initial recruitment and regulation of DNA damage response proteins remains unclear. In this review, the causes of DNA damage, the various mechanisms of DNA damage repair, and the current research regarding the early steps of each major pathway were investigated.
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Affiliation(s)
| | - Donald E. Spratt
- Gustaf H. Carlson School of Chemistry and Biochemistry, Clark University, 950 Main St., Worcester, MA 01610, USA;
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16
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Driscoll R, Hampton L, Abraham NA, Larigan JD, Joseph NF, Hernandez-Vega JC, Geisler S, Yang FC, Deninger M, Tran DT, Khatri N, Godinho BMDC, Kinberger GA, Montagna DR, Hirst WD, Guardado CL, Glajch KE, Arnold HM, Gallant-Behm CL, Weihofen A. Dose-dependent reduction of somatic expansions but not Htt aggregates by di-valent siRNA-mediated silencing of MSH3 in HdhQ111 mice. Sci Rep 2024; 14:2061. [PMID: 38267530 PMCID: PMC10808119 DOI: 10.1038/s41598-024-52667-3] [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: 11/16/2023] [Accepted: 01/22/2024] [Indexed: 01/26/2024] Open
Abstract
Huntington's disease (HD) is a progressive neurodegenerative disorder caused by CAG trinucleotide repeat expansions in exon 1 of the HTT gene. In addition to germline CAG expansions, somatic repeat expansions in neurons also contribute to HD pathogenesis. The DNA mismatch repair gene, MSH3, identified as a genetic modifier of HD onset and progression, promotes somatic CAG expansions, and thus presents a potential therapeutic target. However, what extent of MSH3 protein reduction is needed to attenuate somatic CAG expansions and elicit therapeutic benefits in HD disease models is less clear. In our study, we employed potent di-siRNAs to silence mouse Msh3 mRNA expression in a dose-dependent manner in HdhQ111/+ mice and correlated somatic Htt CAG instability with MSH3 protein levels from simultaneously isolated DNA and protein after siRNA treatment. Our results reveal a linear correlation with a proportionality constant of ~ 1 between the prevention of somatic Htt CAG expansions and MSH3 protein expression in vivo, supporting MSH3 as a rate-limiting step in somatic expansions. Intriguingly, despite a 75% reduction in MSH3 protein levels, striatal nuclear HTT aggregates remained unchanged. We also note that evidence for nuclear Msh3 mRNA that is inaccessible to RNA interference was found, and that MSH6 protein in the striatum was upregulated following MSH3 knockdown in HdhQ111/+ mice. These results provide important clues to address critical questions for the development of therapeutic molecules targeting MSH3 as a potential therapeutic target for HD.
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Affiliation(s)
- Rachelle Driscoll
- Translational Sciences, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - Lucas Hampton
- Neurodegenerative Diseases Research Unit, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - Neeta A Abraham
- Neurodegenerative Diseases Research Unit, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - J Douglas Larigan
- Biotherapeutics and Medicinal Sciences, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - Nadine F Joseph
- Neurodegenerative Diseases Research Unit, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - Juan C Hernandez-Vega
- Neurodegenerative Diseases Research Unit, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - Sarah Geisler
- Translational Sciences, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - Fu-Chia Yang
- Translational Sciences, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - Matthew Deninger
- Atalanta Therapeutics, 51 Sleeper Street, Boston, MA, 02210, USA
| | - David T Tran
- Atalanta Therapeutics, 51 Sleeper Street, Boston, MA, 02210, USA
| | - Natasha Khatri
- Atalanta Therapeutics, 51 Sleeper Street, Boston, MA, 02210, USA
| | | | | | - Daniel R Montagna
- Neurodegenerative Diseases Research Unit, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - Warren D Hirst
- Neurodegenerative Diseases Research Unit, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - Catherine L Guardado
- Neurodegenerative Diseases Research Unit, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - Kelly E Glajch
- Neurodegenerative Diseases Research Unit, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | - H Moore Arnold
- Translational Sciences, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA
| | | | - Andreas Weihofen
- Neurodegenerative Diseases Research Unit, Biogen, 225 Binney Street, Cambridge, MA, 02142, USA.
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17
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Lin Y, Jin X. Effect of ubiquitin protease system on DNA damage response in prostate cancer (Review). Exp Ther Med 2024; 27:33. [PMID: 38125344 PMCID: PMC10731405 DOI: 10.3892/etm.2023.12321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/26/2023] [Indexed: 12/23/2023] Open
Abstract
Genomic instability is an essential hallmark of cancer, and cellular DNA damage response (DDR) defects drive tumorigenesis by disrupting genomic stability. Several studies have identified abnormalities in DDR-associated genes, and a dysfunctional ubiquitin-proteasome system (UPS) is the most common molecular event in metastatic castration-resistant prostate cancer (PCa). For example, mutations in Speckle-type BTB/POZ protein-Ser119 result in DDR downstream target activation deficiency. Skp2 excessive upregulation inhibits homologous recombination repair and promotes cell growth and migration. Abnormally high expression of a deubiquitination enzyme, ubiquitin-specific protease 12, stabilizes E3 ligase MDM2, which further leads to p53 degradation, causing DDR interruption and genomic instability. In the present review, the basic pathways of DDR, UPS dysfunction, and its induced DDR alterations mediated by genomic instability, and especially the potential application of UPS and DDR alterations as biomarkers and therapeutic targets in PCa treatment, were described.
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Affiliation(s)
- Yan Lin
- Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathophysiology, Health Science Center, Ningbo University, Ningbo, Zhejiang 315211, P.R. China
- Department of Oncology, The First Hospital of Ningbo University, Ningbo, Zhejiang 315010, P.R. China
| | - Xiaofeng Jin
- Department of Biochemistry and Molecular Biology, Zhejiang Key Laboratory of Pathophysiology, Health Science Center, Ningbo University, Ningbo, Zhejiang 315211, P.R. China
- Department of Oncology, The First Hospital of Ningbo University, Ningbo, Zhejiang 315010, P.R. China
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18
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Krause A, Anderson DG, Ferreira-Correia A, Dawson J, Baine-Savanhu F, Li PP, Margolis RL. Huntington disease-like 2: insight into neurodegeneration from an African disease. Nat Rev Neurol 2024; 20:36-49. [PMID: 38114648 DOI: 10.1038/s41582-023-00906-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2023] [Indexed: 12/21/2023]
Abstract
Huntington disease (HD)-like 2 (HDL2) is a rare genetic disease caused by an expanded trinucleotide repeat in the JPH3 gene (encoding junctophilin 3) that shows remarkable clinical similarity to HD. To date, HDL2 has been reported only in patients with definite or probable African ancestry. A single haplotype background is shared by patients with HDL2 from different populations, supporting a common African origin for the expansion mutation. Nevertheless, outside South Africa, reports of patients with HDL2 in Africa are scarce, probably owing to limited clinical services across the continent. Systematic comparisons of HDL2 and HD have revealed closely overlapping motor, cognitive and psychiatric features and similar patterns of cerebral and striatal atrophy. The pathogenesis of HDL2 remains unclear but it is proposed to occur through several mechanisms, including loss of protein function and RNA and/or protein toxicity. This Review summarizes our current knowledge of this African-specific HD phenocopy and highlights key areas of overlap between HDL2 and HD. Given the aforementioned similarities in clinical phenotype and pathology, an improved understanding of HDL2 could provide novel insights into HD and other neurodegenerative and/or trinucleotide repeat expansion disorders.
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Affiliation(s)
- Amanda Krause
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - David G Anderson
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- University of Glasgow, Department of Neurology, Institute of Neurological Sciences, Queen Elizabeth University Hospital, Glasgow, UK
| | - Aline Ferreira-Correia
- Department of Psychology, School of Human and Community Development, Faculty of Humanities, University of the Witwatersrand, Johannesburg, South Africa
| | - Jessica Dawson
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Fiona Baine-Savanhu
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Pan P Li
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Russell L Margolis
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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19
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Belgrad J, Tang Q, Hildebrand S, Summers A, Sapp E, Echeverria D, O’Reilly D, Luu E, Bramato B, Allen S, Cooper D, Alterman J, Yamada K, Aronin N, DiFiglia M, Khvorova A. A programmable dual-targeting di-valent siRNA scaffold supports potent multi-gene modulation in the central nervous system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.19.572404. [PMID: 38187561 PMCID: PMC10769306 DOI: 10.1101/2023.12.19.572404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Di-valent short interfering RNA (siRNA) is a promising therapeutic modality that enables sequence-specific modulation of a single target gene in the central nervous system (CNS). To treat complex neurodegenerative disorders, where pathogenesis is driven by multiple genes or pathways, di-valent siRNA must be able to silence multiple target genes simultaneously. Here we present a framework for designing unimolecular "dual-targeting" di-valent siRNAs capable of co-silencing two genes in the CNS. We reconfigured di-valent siRNA - in which two identical, linked siRNAs are made concurrently - to create linear di-valent siRNA - where two siRNAs are made sequentially attached by a covalent linker. This linear configuration, synthesized using commercially available reagents, enables incorporation of two different siRNAs to silence two different targets. We demonstrate that this dual-targeting di-valent siRNA is fully functional in the CNS of mice, supporting at least two months of maximal target silencing. Dual-targeting di-valent siRNA is highly programmable, enabling simultaneous modulation of two different disease-relevant gene pairs (e.g., Huntington's disease: MSH3 and HTT; Alzheimer's disease: APOE and JAK1) with similar potency to a mixture of single-targeting di-valent siRNAs against each gene. This work potentiates CNS modulation of virtually any pair of disease-related targets using a simple unimolecular siRNA.
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Affiliation(s)
- Jillian Belgrad
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Qi Tang
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Sam Hildebrand
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Ashley Summers
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Ellen Sapp
- Department of Neurology, Massachusetts General Hospital; Boston, Massachusetts, USA
| | - Dimas Echeverria
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Dan O’Reilly
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Eric Luu
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Brianna Bramato
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Sarah Allen
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - David Cooper
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Julia Alterman
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Ken Yamada
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Neil Aronin
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
- Department of Medicine, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
| | - Marian DiFiglia
- Department of Neurology, Massachusetts General Hospital; Boston, Massachusetts, USA
| | - Anastasia Khvorova
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
- Program in Molecular Medicine, University of Massachusetts Chan Medical School; Worcester, Massachusetts, USA
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20
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Rajagopal S, Donaldson J, Flower M, Hensman Moss DJ, Tabrizi SJ. Genetic modifiers of repeat expansion disorders. Emerg Top Life Sci 2023; 7:325-337. [PMID: 37861103 PMCID: PMC10754329 DOI: 10.1042/etls20230015] [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: 05/19/2023] [Revised: 09/20/2023] [Accepted: 10/09/2023] [Indexed: 10/21/2023]
Abstract
Repeat expansion disorders (REDs) are monogenic diseases caused by a sequence of repetitive DNA expanding above a pathogenic threshold. A common feature of the REDs is a strong genotype-phenotype correlation in which a major determinant of age at onset (AAO) and disease progression is the length of the inherited repeat tract. Over a disease-gene carrier's life, the length of the repeat can expand in somatic cells, through the process of somatic expansion which is hypothesised to drive disease progression. Despite being monogenic, individual REDs are phenotypically variable, and exploring what genetic modifying factors drive this phenotypic variability has illuminated key pathogenic mechanisms that are common to this group of diseases. Disease phenotypes are affected by the cognate gene in which the expansion is found, the location of the repeat sequence in coding or non-coding regions and by the presence of repeat sequence interruptions. Human genetic data, mouse models and in vitro models have implicated the disease-modifying effect of DNA repair pathways via the mechanisms of somatic mutation of the repeat tract. As such, developing an understanding of these pathways in the context of expanded repeats could lead to future disease-modifying therapies for REDs.
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Affiliation(s)
- Sangeerthana Rajagopal
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, U.K
- UK Dementia Research Institute, University College London, London WCC1N 3BG, U.K
| | - Jasmine Donaldson
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, U.K
- UK Dementia Research Institute, University College London, London WCC1N 3BG, U.K
| | - Michael Flower
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, U.K
- UK Dementia Research Institute, University College London, London WCC1N 3BG, U.K
| | - Davina J Hensman Moss
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, U.K
- UK Dementia Research Institute, University College London, London WCC1N 3BG, U.K
- St George's University of London, London SW17 0RE, U.K
| | - Sarah J Tabrizi
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, Queen Square, London WC1N 3BG, U.K
- UK Dementia Research Institute, University College London, London WCC1N 3BG, U.K
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21
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Völker J, Breslauer KJ. How sequence alterations enhance the stability and delay expansion of DNA triplet repeat domains. QRB DISCOVERY 2023; 4:e8. [PMID: 37965436 PMCID: PMC10641665 DOI: 10.1017/qrd.2023.6] [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: 06/19/2023] [Revised: 08/14/2023] [Accepted: 08/17/2023] [Indexed: 11/16/2023] Open
Abstract
DNA sequence alterations within DNA repeat domains inexplicably enhance the stability and delay the expansion of interrupted repeat domains. Here we propose mechanisms that rationalise such unanticipated outcomes. Specifically, we describe how interruption of a DNA repeat domain restricts the ensemble space available to dynamic, slip out, repeat bulge loops by introducing energetic barriers to loop migration. We explain how such barriers arise because some possible loop isomers result in energetically costly mismatches in the duplex portion of the repeat domain. We propose that the reduced ensemble space is the causative feature for the observed delay in repeat DNA expansion. We further posit that the observed loss of the interrupting repeat in some expanded DNAs reflects the transient occupation of loop isomer positions that result in a mismatch in the duplex stem due to 'leakiness' in the energy barrier. We propose that if the lifetime of such a low probability event allows for recognition by the mismatch repair system, then 'repair' of the repeat interruption can occur; thereby rationalising the absence of the interruption in the final expanded DNA 'product.' Our proposed mechanistic pathways provide reasoned explanations for what have been described as 'puzzling' observations, while also yielding insights into a biomedically important set of coupled genotypic phenomena that map the linkage between DNA origami thermodynamics and phenotypic disease states.
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Affiliation(s)
- Jens Völker
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, USA
| | - Kenneth J. Breslauer
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ, USA
- The Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, USA
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22
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Phadte AS, Bhatia M, Ebert H, Abdullah H, Elrazaq EA, Komolov KE, Pluciennik A. FAN1 removes triplet repeat extrusions via a PCNA- and RFC-dependent mechanism. Proc Natl Acad Sci U S A 2023; 120:e2302103120. [PMID: 37549289 PMCID: PMC10438374 DOI: 10.1073/pnas.2302103120] [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: 02/06/2023] [Accepted: 06/22/2023] [Indexed: 08/09/2023] Open
Abstract
Human genome-wide association studies have identified FAN1 and several DNA mismatch repair (MMR) genes as modifiers of Huntington's disease age of onset. In animal models, FAN1 prevents somatic expansion of CAG triplet repeats, whereas MMR proteins promote this process. To understand the molecular basis of these opposing effects, we evaluated FAN1 nuclease function on DNA extrahelical extrusions that represent key intermediates in triplet repeat expansion. Here, we describe a strand-directed, extrusion-provoked nuclease function of FAN1 that is activated by RFC, PCNA, and ATP at physiological ionic strength. Activation of FAN1 in this manner results in DNA cleavage in the vicinity of triplet repeat extrahelical extrusions thereby leading to their removal in human cell extracts. The role of PCNA and RFC is to confer strand directionality to the FAN1 nuclease, and this reaction requires a physical interaction between PCNA and FAN1. Using cell extracts, we show that FAN1-dependent CAG extrusion removal relies on a very short patch excision-repair mechanism that competes with MutSβ-dependent MMR which is characterized by longer excision tracts. These results provide a mechanistic basis for the role of FAN1 in preventing repeat expansion and could explain the antagonistic effects of MMR and FAN1 in disease onset/progression.
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Affiliation(s)
- Ashutosh S. Phadte
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Mayuri Bhatia
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Hope Ebert
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Haaris Abdullah
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Essam Abed Elrazaq
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Konstantin E. Komolov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
| | - Anna Pluciennik
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA19107
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23
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McLean ZL, Gao D, Correia K, Roy JCL, Shibata S, Farnum IN, Valdepenas-Mellor Z, Rapuru M, Morini E, Ruliera J, Gillis T, Lucente D, Kleinstiver BP, Lee JM, MacDonald ME, Wheeler VC, Pinto RM, Gusella JF. PMS1 as a target for splice modulation to prevent somatic CAG repeat expansion in Huntington's disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.25.550489. [PMID: 37547003 PMCID: PMC10402039 DOI: 10.1101/2023.07.25.550489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder whose motor, cognitive, and behavioral manifestations are caused by an expanded, somatically unstable CAG repeat in the first exon of HTT that lengthens a polyglutamine tract in huntingtin. Genome-wide association studies (GWAS) have revealed DNA repair genes that influence the age-at-onset of HD and implicate somatic CAG repeat expansion as the primary driver of disease timing. To prevent the consequent neuronal damage, small molecule splice modulators (e.g., branaplam) that target HTT to reduce the levels of huntingtin are being investigated as potential HD therapeutics. We found that the effectiveness of the splice modulators can be influenced by genetic variants, both at HTT and other genes where they promote pseudoexon inclusion. Surprisingly, in a novel hTERT-immortalized retinal pigment epithelial cell (RPE1) model for assessing CAG repeat instability, these drugs also reduced the rate of HTT CAG expansion. We determined that the splice modulators also affect the expression of the mismatch repair gene PMS1, a known modifier of HD age-at-onset. Genome editing at specific HTT and PMS1 sequences using CRISPR-Cas9 nuclease confirmed that branaplam suppresses CAG expansion by promoting the inclusion of a pseudoexon in PMS1, making splice modulation of PMS1 a potential strategy for delaying HD onset. Comparison with another splice modulator, risdiplam, suggests that other genes affected by these splice modulators also influence CAG instability and might provide additional therapeutic targets.
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Affiliation(s)
- Zachariah L. McLean
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Dadi Gao
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Kevin Correia
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Jennie C. L. Roy
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Shota Shibata
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Iris N. Farnum
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Zoe Valdepenas-Mellor
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Manasa Rapuru
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Elisabetta Morini
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Jayla Ruliera
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Tammy Gillis
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Diane Lucente
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Benjamin P. Kleinstiver
- Center for Genomic Medicine and Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
| | - Jong-Min Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Marcy E. MacDonald
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - Vanessa C. Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Ricardo Mouro Pinto
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
| | - James F. Gusella
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Medical and Population Genetics Program, the Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
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24
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Yakushina V, Kavun A, Veselovsky E, Grigoreva T, Belova E, Lebedeva A, Mileyko V, Ivanov M. Microsatellite Instability Detection: The Current Standards, Limitations, and Misinterpretations. JCO Precis Oncol 2023; 7:e2300010. [PMID: 37315263 DOI: 10.1200/po.23.00010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 04/06/2023] [Accepted: 04/26/2023] [Indexed: 06/16/2023] Open
Affiliation(s)
- Valentina Yakushina
- OncoAtlas LLC, Moscow, Russian Federation
- Laboratory of Epigenetics, Research Centre for Medical Genetics, Moscow, Russian Federation
| | | | - Egor Veselovsky
- OncoAtlas LLC, Moscow, Russian Federation
- Department of Evolutionary Genetics of Development, Koltzov Institute of Developmental Biology of the Russian Academy of Sciences, Moscow, Russian Federation
| | - Tatiana Grigoreva
- OncoAtlas LLC, Moscow, Russian Federation
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Ekaterina Belova
- OncoAtlas LLC, Moscow, Russian Federation
- Lomonosov Moscow State University, Moscow, Russian Federation
| | | | | | - Maxim Ivanov
- OncoAtlas LLC, Moscow, Russian Federation
- Moscow Institute of Physics and Technology, Moscow, Russian Federation
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25
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Xu P, Zhang J, Pan F, Mahn C, Roland C, Sagui C, Weninger K. Frustration Between Preferred States of Complementary Trinucleotide Repeat DNA Hairpins Anticorrelates with Expansion Disease Propensity. J Mol Biol 2023; 435:168086. [PMID: 37024008 PMCID: PMC10191799 DOI: 10.1016/j.jmb.2023.168086] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 03/21/2023] [Accepted: 03/30/2023] [Indexed: 04/08/2023]
Abstract
DNA trinucleotide repeat (TRs) expansion beyond a threshold often results in human neurodegenerative diseases. The mechanisms causing expansions remain unknown, although the tendency of TR ssDNA to self-associate into hairpins that slip along their length is widely presumed related. Here we apply single molecule FRET (smFRET) experiments and molecular dynamics simulations to determine conformational stabilities and slipping dynamics for CAG, CTG, GAC and GTC hairpins. Tetraloops are favored in CAG (89%), CTG (89%) and GTC (69%) while GAC favors triloops. We also determined that TTG interrupts near the loop in the CTG hairpin stabilize the hairpin against slipping. The different loop stabilities have implications for intermediate structures that may form when TR-containing duplex DNA opens. Opposing hairpins in the (CAG) ∙ (CTG) duplex would have matched stability whereas opposing hairpins in a (GAC) ∙ (GTC) duplex would have unmatched stability, introducing frustration in the (GAC) ∙ (GTC) opposing hairpins that could encourage their resolution to duplex DNA more rapidly than in (CAG) ∙ (CTG) structures. Given that the CAG and CTG TR can undergo large, disease-related expansion whereas the GAC and GTC sequences do not, these stability differences can inform and constrain models of expansion mechanisms of TR regions.
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Affiliation(s)
- Pengning Xu
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA. https://twitter.com/@XPengning
| | - Jiahui Zhang
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Feng Pan
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Chelsea Mahn
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Christopher Roland
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Celeste Sagui
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA.
| | - Keith Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA.
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26
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Kavun A, Veselovsky E, Lebedeva A, Belova E, Kuznetsova O, Yakushina V, Grigoreva T, Mileyko V, Fedyanin M, Ivanov M. Microsatellite Instability: A Review of Molecular Epidemiology and Implications for Immune Checkpoint Inhibitor Therapy. Cancers (Basel) 2023; 15:cancers15082288. [PMID: 37190216 DOI: 10.3390/cancers15082288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/10/2023] [Accepted: 04/11/2023] [Indexed: 05/17/2023] Open
Abstract
Microsatellite instability (MSI) is one of the most important molecular characteristics of a tumor, which occurs among various tumor types. In this review article, we examine the molecular characteristics of MSI tumors, both sporadic and Lynch-associated. We also overview the risks of developing hereditary forms of cancer and potential mechanisms of tumor development in patients with Lynch syndrome. Additionally, we summarize the results of major clinical studies on the efficacy of immune checkpoint inhibitors for MSI tumors and discuss the predictive role of MSI in the context of chemotherapy and checkpoint inhibitors. Finally, we briefly discuss some of the underlying mechanisms causing therapy resistance in patients treated with immune checkpoint inhibitors.
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Affiliation(s)
| | - Egor Veselovsky
- OncoAtlas LLC, 119049 Moscow, Russia
- Department of Evolutionary Genetics of Development, Koltzov Institute of Developmental Biology of the Russian Academy of Sciences, 119334 Moscow, Russia
| | | | - Ekaterina Belova
- OncoAtlas LLC, 119049 Moscow, Russia
- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Olesya Kuznetsova
- OncoAtlas LLC, 119049 Moscow, Russia
- N.N. Blokhin Russian Cancer Research Center, 115478 Moscow, Russia
| | - Valentina Yakushina
- OncoAtlas LLC, 119049 Moscow, Russia
- Laboratory of Epigenetics, Research Centre for Medical Genetics, 115522 Moscow, Russia
| | - Tatiana Grigoreva
- OncoAtlas LLC, 119049 Moscow, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 117997 Moscow, Russia
| | | | - Mikhail Fedyanin
- N.N. Blokhin Russian Cancer Research Center, 115478 Moscow, Russia
- State Budgetary Institution of Health Care of the City of Moscow "Moscow Multidisciplinary Clinical Center" "Kommunarka" of the Department of Health of the City of Moscow, 142770 Moscow, Russia
- Federal State Budgetary Institution "National Medical and Surgical Center named after N.I. Pirogov" of the Ministry of Health of the Russian Federation, 105203 Moscow, Russia
| | - Maxim Ivanov
- OncoAtlas LLC, 119049 Moscow, Russia
- Moscow Institute of Physics and Technology, 141701 Dolgoprudny, Russia
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27
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Torigoe H, Kondo J, Arakawa F. Specific binding of Hg 2+ to mismatched base pairs involving 5-hydroxyuracil in duplex DNA. J Inorg Biochem 2023; 241:112125. [PMID: 36716510 DOI: 10.1016/j.jinorgbio.2023.112125] [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: 08/28/2022] [Revised: 01/07/2023] [Accepted: 01/08/2023] [Indexed: 01/13/2023]
Abstract
Metal ion-nucleic acid interactions contribute significantly to nucleic acid structure and biological activity and have potential applications in nanotechnology. Hg2+ specifically binds to the natural T-T mismatched base pair in duplex DNA to form a T-Hg-T base pair. Metal ions may enhance DNA damage induced by DNA-damaging agents, such as oxidative agents. The interactions between metal ions and damaged DNAs, such as mismatched oxidized bases, have not been well characterized. Here, we examined the possibility of Hg2+ binding to an asymmetric mismatched base pair involving thymine and 5-hydroxyuracil (OHdU), an oxidized base produced by the oxidative deamination of cytosine. UV melting analyses showed that only the melting temperature of the single T-OHdU mismatched duplex DNA increased upon Hg2+ addition. CD spectra indicated no significant change in the higher-order structure of the single T-OHdU mismatched duplex DNA upon Hg2+ addition. X-ray crystallographic structure with two consecutive T-OHdU mismatched base pairs and isothermal titration calorimetric analyses with the single T-OHdU mismatched base pair showed that Hg2+ specifically binds to the N3 positions of both T and OHdU in T-OHdU at 1:1 molar ratio, with a 5×105 M-1 binding constant of to form the T-Hg-OHdU base pair. The Hg2+-bound structure and the Hg2+-binding affinity for T-OHdU was similar to those for T-T. This study on T-Hg-OHdU metal-mediated base pair could aid in studying the molecular mechanism of metal ion-mediated DNA damage and their potential applications in nanotechnology.
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Affiliation(s)
- Hidetaka Torigoe
- Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan.
| | - Jiro Kondo
- Department of Materials and Life Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan
| | - Fumihiro Arakawa
- Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
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28
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Lange J, Gillham O, Flower M, Ging H, Eaton S, Kapadia S, Neueder A, Duchen MR, Ferretti P, Tabrizi SJ. PolyQ length-dependent metabolic alterations and DNA damage drive human astrocyte dysfunction in Huntington’s disease. Prog Neurobiol 2023; 225:102448. [PMID: 37023937 DOI: 10.1016/j.pneurobio.2023.102448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 02/03/2023] [Accepted: 03/24/2023] [Indexed: 04/07/2023]
Abstract
Huntington's Disease (HD) is a neurodegenerative disease caused by a polyglutamine (polyQ) expansion in the Huntingtin gene. Astrocyte dysfunction is known to contribute to HD pathology, however our understanding of the molecular pathways involved is limited. Transcriptomic analysis of patient-derived PSC (pluripotent stem cells) astrocyte lines revealed that astrocytes with similar polyQ lengths shared a large number of differentially expressed genes (DEGs). Notably, weighted correlation network analysis (WGCNA) modules from iPSC derived astrocytes showed significant overlap with WGCNA modules from two post-mortem HD cohorts. Further experiments revealed two key elements of astrocyte dysfunction. Firstly, expression of genes linked to astrocyte reactivity, as well as metabolic changes were polyQ length-dependent. Hypermetabolism was observed in shorter polyQ length astrocytes compared to controls, whereas metabolic activity and release of metabolites were significantly reduced in astrocytes with increasing polyQ lengths. Secondly, all HD astrocytes showed increased DNA damage, DNA damage response and upregulation of mismatch repair genes and proteins. Together our study shows for the first time polyQ-dependent phenotypes and functional changes in HD astrocytes providing evidence that increased DNA damage and DNA damage response could contribute to HD astrocyte dysfunction.
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29
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Modulation of Synaptic Plasticity Genes Associated to DNA Damage in a Model of Huntington's Disease. Neurochem Res 2023; 48:2093-2103. [PMID: 36790580 DOI: 10.1007/s11064-023-03889-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/16/2023]
Abstract
Huntington's disease (HD) is a disease characterized by the progressive degeneration of nerve cells in the brain. DNA damage has been implicated in many neurological disorders; however, the association between this damage and the impaired signaling related to neurodegeneration is still unclear. The transcription factor c-AMP-responsive element binding protein (CREB) has a relevant role in the neuronal plasticity process regulating the expression of several genes, including brain-derived neurotrophic factor (BDNF). Here we analyzed the direct link between DNA damage and the expression of genes involved in neuronal plasticity. The study was performed in model cell lines STHdhQ7 (wild type) and STHdhQ111 (HD model). Treatment with Etoposide (Eto) was used to induce double-strand breaks (DSBs) to evaluate the DNA damage response (DDR) and the expression of synaptic plasticity genes. Eto treatment induced phosphorylation of ATM (p-ATM) and H2AX (γH2AX), markers of DDR, in both cell lines. Interestingly, upon DNA damage, STHdhQ7 cells showed increased expression of activity-regulated cytoskeleton associated protein (Arc) and BDNF when compared to the HD cell line model. Additionally, Eto induced CREB activation with a differential localization of its co-activators in the cell types analyzed. These results suggest that DSBs impact differentially the gene expression patterns of plasticity genes in the normal cell line versus the HD model. This effect is mediated by the impaired localization of CREB-binding protein (CBP) and histone acetylation in the HD model. Our results highlight the role of epigenetics and DNA repair on HD and therefore we suggest that future studies should explore in depth the epigenetic landscape on neuronal pathologies with the goal to further understand molecular mechanisms and pinpoint therapeutic targets.
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Mengoli V, Ceppi I, Sanchez A, Cannavo E, Halder S, Scaglione S, Gaillard P, McHugh PJ, Riesen N, Pettazzoni P, Cejka P. WRN helicase and mismatch repair complexes independently and synergistically disrupt cruciform DNA structures. EMBO J 2023; 42:e111998. [PMID: 36541070 PMCID: PMC9890227 DOI: 10.15252/embj.2022111998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 11/07/2022] [Accepted: 12/06/2022] [Indexed: 12/24/2022] Open
Abstract
The Werner Syndrome helicase, WRN, is a promising therapeutic target in cancers with microsatellite instability (MSI). Long-term MSI leads to the expansion of TA nucleotide repeats proposed to form cruciform DNA structures, which in turn cause DNA breaks and cell lethality upon WRN downregulation. Here we employed biochemical assays to show that WRN helicase can efficiently and directly unfold cruciform structures, thereby preventing their cleavage by the SLX1-SLX4 structure-specific endonuclease. TA repeats are particularly prone to form cruciform structures, explaining why these DNA sequences are preferentially broken in MSI cells upon WRN downregulation. We further demonstrate that the activity of the DNA mismatch repair (MMR) complexes MutSα (MSH2-MSH6), MutSβ (MSH2-MSH3), and MutLα (MLH1-PMS2) similarly decreases the level of DNA cruciforms, although the mechanism is different from that employed by WRN. When combined, WRN and MutLα exhibited higher than additive effects in in vitro cruciform processing, suggesting that WRN and the MMR proteins may cooperate. Our data explain how WRN and MMR defects cause genome instability in MSI cells with expanded TA repeats, and provide a mechanistic basis for their recently discovered synthetic-lethal interaction with promising applications in precision cancer therapy.
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Affiliation(s)
- Valentina Mengoli
- Faculty of Biomedical Sciences, Institute for Research in BiomedicineUniversità della Svizzera italiana (USI)BellinzonaSwitzerland
| | - Ilaria Ceppi
- Faculty of Biomedical Sciences, Institute for Research in BiomedicineUniversità della Svizzera italiana (USI)BellinzonaSwitzerland
| | - Aurore Sanchez
- Faculty of Biomedical Sciences, Institute for Research in BiomedicineUniversità della Svizzera italiana (USI)BellinzonaSwitzerland
| | - Elda Cannavo
- Faculty of Biomedical Sciences, Institute for Research in BiomedicineUniversità della Svizzera italiana (USI)BellinzonaSwitzerland
| | - Swagata Halder
- Faculty of Biomedical Sciences, Institute for Research in BiomedicineUniversità della Svizzera italiana (USI)BellinzonaSwitzerland
| | - Sarah Scaglione
- Centre de Recherche en Cancérologie de Marseille, CRCM, Inserm, CNRS, Aix‐Marseille Université, Institut Paoli‐CalmettesMarseilleFrance
| | - Pierre‐Henri Gaillard
- Centre de Recherche en Cancérologie de Marseille, CRCM, Inserm, CNRS, Aix‐Marseille Université, Institut Paoli‐CalmettesMarseilleFrance
| | - Peter J McHugh
- Department of Oncology, MRC Weatherall Institute of Molecular Medicine, John Radcliffe HospitalUniversity of OxfordOxfordUK
| | - Nathalie Riesen
- Roche Pharma Research & Early Development pREDRoche Innovation CenterBaselSwitzerland
| | | | - Petr Cejka
- Faculty of Biomedical Sciences, Institute for Research in BiomedicineUniversità della Svizzera italiana (USI)BellinzonaSwitzerland
- Department of Biology, Institute of BiochemistryEidgenössische Technische Hochschule (ETH)ZürichSwitzerland
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31
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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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van der Bent ML, Evers MM, Vallès A. Emerging Therapies for Huntington's Disease - Focus on N-Terminal Huntingtin and Huntingtin Exon 1. Biologics 2022; 16:141-160. [PMID: 36213816 PMCID: PMC9532260 DOI: 10.2147/btt.s270657] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 09/14/2022] [Indexed: 11/12/2022]
Abstract
Huntington's disease is a devastating heritable neurodegenerative disorder that is caused by the presence of a trinucleotide CAG repeat expansion in the Huntingtin gene, leading to a polyglutamine tract in the protein. Various mechanisms lead to the production of N-terminal Huntingtin protein fragments, which are reportedly more toxic than the full-length protein. In this review, we summarize the current knowledge on the production and toxicity of N-terminal Huntingtin protein fragments. Further, we expand on various therapeutic strategies targeting N-terminal Huntingtin on the protein, RNA and DNA level. Finally, we compare the therapeutic approaches that are clinically most advanced, including those that do not target N-terminal Huntingtin, discussing differences in mode of action and translational applicability.
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Affiliation(s)
| | - Melvin M Evers
- uniQure biopharma B.V., Department of Research and Development, Amsterdam, the Netherlands
| | - Astrid Vallès
- uniQure biopharma B.V., Department of Research and Development, Amsterdam, the Netherlands
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Heterogeneous migration routes of DNA triplet repeat slip-outs. BIOPHYSICAL REPORTS 2022; 2:None. [PMID: 36299495 PMCID: PMC9586884 DOI: 10.1016/j.bpr.2022.100070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 08/08/2022] [Indexed: 12/02/2022]
Abstract
It is unclear how the length of a repetitive DNA tract determines the onset and progression of repeat expansion diseases, but the dynamics of secondary DNA structures formed by repeat sequences are believed to play an important role. It was recently shown that three-way DNA junctions containing slip-out hairpins of CAG or CTG repeats and contiguous triplet repeats in the adjacent duplex displayed single-molecule FRET (smFRET) dynamics that were ascribed to both local conformational motions and longer-range branch migration. Here we explore these so-called "mobile" slip-out structures through a detailed kinetic analysis of smFRET trajectories and coarse-grained modeling. Despite the apparent structural simplicity, with six FRET states resolvable, most smFRET states displayed biexponential dwell-time distributions, attributed to structural heterogeneity and overlapping FRET states. Coarse-grained modeling for a (GAC)10 repeat slip-out included trajectories that corresponded to a complete round of branch migration; the structured free energy landscape between slippage events supports the dynamical complexity observed by smFRET. A hairpin slip-out with 40 CAG repeats, which is above the repeat length required for disease in several triplet repeat disorders, displayed smFRET dwell times that were on average double those of 3WJs with 10 repeats. The rate of secondary-structure rearrangement via branch migration, relative to particular DNA processing pathways, may be an important factor in the expansion of triplet repeat expansion diseases.
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34
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Seefelder M, Klein FAC, Landwehrmeyer B, Fernández-Busnadiego R, Kochanek S. Huntingtin and Its Partner Huntingtin-Associated Protein 40: Structural and Functional Considerations in Health and Disease. J Huntingtons Dis 2022; 11:227-242. [PMID: 35871360 PMCID: PMC9484127 DOI: 10.3233/jhd-220543] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Since the discovery of the mutation causing Huntington’s disease (HD) in 1993, it has been debated whether an expanded polyglutamine (polyQ) stretch affects the properties of the huntingtin (HTT) protein and thus contributes to the pathological mechanisms responsible for HD. Here we review the current knowledge about the structure of HTT, alone (apo-HTT) or in a complex with Huntingtin-Associated Protein 40 (HAP40), the influence of polyQ-length variation on apo-HTT and the HTT-HAP40 complex, and the biology of HAP40. Phylogenetic analyses suggest that HAP40 performs essential functions. Highlighting the relevance of its interaction with HTT, HAP40 is one of the most abundant partners copurifying with HTT and is rapidly degraded, when HTT levels are reduced. As the levels of both proteins decrease during disease progression, HAP40 could also be a biomarker for HD. Whether declining HAP40 levels contribute to disease etiology is an open question. Structural studies have shown that the conformation of apo-HTT is less constrained but resembles that adopted in the HTT-HAP40 complex, which is exceptionally stable because of extensive interactions between HAP40 and the three domains of HTT. The complex— and to some extent apo-HTT— resists fragmentation after limited proteolysis. Unresolved regions of apo-HTT, constituting about 25% of the protein, are the main sites of post-translational modifications and likely have major regulatory functions. PolyQ elongation does not substantially alter the structure of HTT, alone or when associated with HAP40. Particularly, polyQ above the disease length threshold does not induce drastic conformational changes in full-length HTT. Therefore, models of HD pathogenesis stating that polyQ expansion drastically alters HTT properties should be reconsidered.
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Affiliation(s)
| | | | | | - Rubén Fernández-Busnadiego
- Institute of Neuropathology, University Medical Center Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
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35
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Tabrizi SJ, Estevez-Fraga C, van Roon-Mom WMC, Flower MD, Scahill RI, Wild EJ, Muñoz-Sanjuan I, Sampaio C, Rosser AE, Leavitt BR. Potential disease-modifying therapies for Huntington's disease: lessons learned and future opportunities. Lancet Neurol 2022; 21:645-658. [PMID: 35716694 PMCID: PMC7613206 DOI: 10.1016/s1474-4422(22)00121-1] [Citation(s) in RCA: 101] [Impact Index Per Article: 50.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 02/18/2022] [Accepted: 03/04/2022] [Indexed: 01/03/2023]
Abstract
Huntington's disease is the most frequent autosomal dominant neurodegenerative disorder; however, no disease-modifying interventions are available for patients with this disease. The molecular pathogenesis of Huntington's disease is complex, with toxicity that arises from full-length expanded huntingtin and N-terminal fragments of huntingtin, which are both prone to misfolding due to proteolysis; aberrant intron-1 splicing of the HTT gene; and somatic expansion of the CAG repeat in the HTT gene. Potential interventions for Huntington's disease include therapies targeting huntingtin DNA and RNA, clearance of huntingtin protein, DNA repair pathways, and other treatment strategies targeting inflammation and cell replacement. The early termination of trials of the antisense oligonucleotide tominersen suggest that it is time to reflect on lessons learned, where the field stands now, and the challenges and opportunities for the future.
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Affiliation(s)
- Sarah J Tabrizi
- Huntington's Disease Centre, UCL Queen Square Institute of Neurology, University College London, London, UK.
| | - Carlos Estevez-Fraga
- Huntington's Disease Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | | | - Michael D Flower
- Huntington's Disease Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Rachael I Scahill
- Huntington's Disease Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Edward J Wild
- Huntington's Disease Centre, UCL Queen Square Institute of Neurology, University College London, London, UK
| | | | - Cristina Sampaio
- CHDI Management, CHDI Foundation Los Angeles, CA, USA; Laboratory of Clinical Pharmacology, Faculdade de Medicina de Lisboa, Lisbon, Portugal
| | - Anne E Rosser
- BRAIN unit, Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University, Cardiff, UK
| | - Blair R Leavitt
- Centre for Huntington's disease, University of British Columbia, Vancouver, BC, Canada
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Konopka A, Atkin JD. The Role of DNA Damage in Neural Plasticity in Physiology and Neurodegeneration. Front Cell Neurosci 2022; 16:836885. [PMID: 35813507 PMCID: PMC9259845 DOI: 10.3389/fncel.2022.836885] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 05/09/2022] [Indexed: 12/15/2022] Open
Abstract
Damage to DNA is generally considered to be a harmful process associated with aging and aging-related disorders such as neurodegenerative diseases that involve the selective death of specific groups of neurons. However, recent studies have provided evidence that DNA damage and its subsequent repair are important processes in the physiology and normal function of neurons. Neurons are unique cells that form new neural connections throughout life by growth and re-organisation in response to various stimuli. This “plasticity” is essential for cognitive processes such as learning and memory as well as brain development, sensorial training, and recovery from brain lesions. Interestingly, recent evidence has suggested that the formation of double strand breaks (DSBs) in DNA, the most toxic form of damage, is a physiological process that modifies gene expression during normal brain activity. Together with subsequent DNA repair, this is thought to underlie neural plasticity and thus control neuronal function. Interestingly, neurodegenerative diseases such as Alzheimer’s disease, amyotrophic lateral sclerosis, frontotemporal dementia, and Huntington’s disease, manifest by a decline in cognitive functions, which are governed by plasticity. This suggests that DNA damage and DNA repair processes that normally function in neural plasticity may contribute to neurodegeneration. In this review, we summarize current understanding about the relationship between DNA damage and neural plasticity in physiological conditions, as well as in the pathophysiology of neurodegenerative diseases.
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Affiliation(s)
- Anna Konopka
- Centre for Motor Neuron Disease Research, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia
- *Correspondence: Anna Konopka
| | - Julie D. Atkin
- Centre for Motor Neuron Disease Research, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
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37
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Genome Integrity and Neurological Disease. Int J Mol Sci 2022; 23:ijms23084142. [PMID: 35456958 PMCID: PMC9025063 DOI: 10.3390/ijms23084142] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 04/02/2022] [Accepted: 04/05/2022] [Indexed: 02/06/2023] Open
Abstract
Neurological complications directly impact the lives of hundreds of millions of people worldwide. While the precise molecular mechanisms that underlie neuronal cell loss remain under debate, evidence indicates that the accumulation of genomic DNA damage and consequent cellular responses can promote apoptosis and neurodegenerative disease. This idea is supported by the fact that individuals who harbor pathogenic mutations in DNA damage response genes experience profound neuropathological manifestations. The review article here provides a general overview of the nervous system, the threats to DNA stability, and the mechanisms that protect genomic integrity while highlighting the connections of DNA repair defects to neurological disease. The information presented should serve as a prelude to the Special Issue “Genome Stability and Neurological Disease”, where experts discuss the role of DNA repair in preserving central nervous system function in greater depth.
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Chen X, Zhang G, Li P, Yu J, Kang L, Qin B, Wang Y, Wu J, Wang Y, Zhang J, Qin M, Guan H. SYVN1-mediated ubiquitination and degradation of MSH3 promotes the apoptosis of lens epithelial cells. FEBS J 2022; 289:5682-5696. [PMID: 35334159 DOI: 10.1111/febs.16447] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 11/24/2021] [Accepted: 03/24/2022] [Indexed: 12/29/2022]
Abstract
The pathology of age-related cataract (ARC) mainly involves the misfolding and aggregation of proteins, especially oxidative damage repair proteins, in the lens, induced by ultraviolet-B (UVB). MSH3, as a key member of the mismatch repair family, primarily maintains genome stability. However, the function of MSH3 and the mechanism by which cells maintain MSH3 proteostasis during cataractogenesis remains unknown. In the present study, the protein expression levels of MSH3 were found to be attenuated in ARC specimens and SRA01/04 cells under UVB exposure. The ectopic expression of MSH3 notably impeded UVB-induced apoptosis, whereas the knockdown of MSH3 promoted apoptosis. Protein half-life assay revealed that UVB irradiation accelerated the decline of MSH3 by ubiquitination and degradation. Subsequently, we found that E3 ubiquitin ligase synoviolin (SYVN1) interacted with MSH3 and promoted its ubiquitination and degradation. Of note, the expression and function of SYVN1 were contrary to those of MSH3 and SYVN1 regulated MSH3 protein degradation via the ubiquitin-proteasome pathway and the autophagy-lysosome pathway. Based on these findings, we propose a mechanism for ARC pathogenesis that involves SYVN1-mediated degradation of MSH3 via the ubiquitin-proteasome pathway and the autophagy-lysosome pathway, and suggest that interventions targeting SYVN1 might be a potential therapeutic strategy for ARC.
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Affiliation(s)
- Xiaojuan Chen
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Guowei Zhang
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Pengfei Li
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Jianfeng Yu
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Lihua Kang
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Bai Qin
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Ying Wang
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Jian Wu
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Yong Wang
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Junfang Zhang
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Miaomiao Qin
- Eye Institute, Affiliated Hospital of Nantong University, China
| | - Huaijin Guan
- Eye Institute, Affiliated Hospital of Nantong University, China
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Ghanekar SD, Kuo SH, Staffetti JS, Zesiewicz TA. Current and Emerging Treatment Modalities for Spinocerebellar Ataxias. Expert Rev Neurother 2022; 22:101-114. [PMID: 35081319 DOI: 10.1080/14737175.2022.2029703] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Spinocerebellar ataxias (SCA) are a group of rare neurodegenerative diseases that dramatically affect the lives of affected individuals and their families. Despite having a clear understanding of SCA's etiology, there are no current symptomatic or neuroprotective treatments approved by the FDA. AREAS COVERED Research efforts have greatly expanded the possibilities for potential treatments, including both pharmacological and non-pharmacological interventions. Great attention is also being given to novel therapeutics based in gene therapy, neurostimulation, and molecular targeting. This review article will address the current advances in the treatment of SCA and what potential interventions are on the horizon. EXPERT OPINION SCA is a highly complex and multifaceted disease family with the majority of research emphasizing symptomatic pharmacologic therapies. As pre-clinical trials for SCA and clinical trials for other neurodegenerative conditions illuminate the efficacy of disease modifying therapies such as AAV-mediated gene therapy and ASOs, the potential for addressing SCA at the pre-symptomatic stage is increasingly promising.
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Affiliation(s)
- Shaila D Ghanekar
- University of South Florida (USF) Department of Neurology, USF Ataxia Research Center, Tampa, Florida, USA.,James A Haley Veteran's Hospital, Tampa, Florida, USA
| | - Sheng-Han Kuo
- Department of Neurology, Columbia University, New York, New York, USA.,Initiative for Columbia Ataxia and Tremor, New York, New York, USA
| | - Joseph S Staffetti
- University of South Florida (USF) Department of Neurology, USF Ataxia Research Center, Tampa, Florida, USA.,James A Haley Veteran's Hospital, Tampa, Florida, USA
| | - Theresa A Zesiewicz
- University of South Florida (USF) Department of Neurology, USF Ataxia Research Center, Tampa, Florida, USA.,James A Haley Veteran's Hospital, Tampa, Florida, USA
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40
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Wipf P, Polyzos AA, McMurray CT. A Double-Pronged Sword: XJB-5-131 Is a Suppressor of Somatic Instability and Toxicity in Huntington's Disease. J Huntingtons Dis 2022; 11:3-15. [PMID: 34924397 PMCID: PMC9028625 DOI: 10.3233/jhd-210510] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Due to large increases in the elderly populations across the world, age-related diseases are expected to expand dramatically in the coming years. Among these, neurodegenerative diseases will be among the most devastating in terms of their emotional and economic impact on patients, their families, and associated subsidized health costs. There is no currently available cure or rescue for dying brain cells. Viable therapeutics for any of these disorders would be a breakthrough and provide relief for the large number of affected patients and their families. Neurodegeneration is accompanied by elevated oxidative damage and inflammation. While natural antioxidants have largely failed in clinical trials, preclinical phenotyping of the unnatural, mitochondrial targeted nitroxide, XJB-5-131, bodes well for further translational development in advanced animal models or in humans. Here we consider the usefulness of synthetic antioxidants for the treatment of Huntington's disease. The mitochondrial targeting properties of XJB-5-131 have great promise. It is both an electron scavenger and an antioxidant, reducing both somatic expansion and toxicity simultaneously through the same redox mechanism. By quenching reactive oxygen species, XJB-5-131 breaks the cycle between the rise in oxidative damage during disease progression and the somatic growth of the CAG repeat which depends on oxidation.
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Affiliation(s)
- Pater Wipf
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Aris A. Polyzos
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Cynthia T. McMurray
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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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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42
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Gold MA, Whalen JM, Freon K, Hong Z, Iraqui I, Lambert SAE, Freudenreich CH. Restarted replication forks are error-prone and cause CAG repeat expansions and contractions. PLoS Genet 2021; 17:e1009863. [PMID: 34673780 PMCID: PMC8562783 DOI: 10.1371/journal.pgen.1009863] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 11/02/2021] [Accepted: 10/06/2021] [Indexed: 12/16/2022] Open
Abstract
Disease-associated trinucleotide repeats form secondary DNA structures that interfere with replication and repair. Replication has been implicated as a mechanism that can cause repeat expansions and contractions. However, because structure-forming repeats are also replication barriers, it has been unclear whether the instability occurs due to slippage during normal replication progression through the repeat, slippage or misalignment at a replication stall caused by the repeat, or during subsequent replication of the repeat by a restarted fork that has altered properties. In this study, we have specifically addressed the fidelity of a restarted fork as it replicates through a CAG/CTG repeat tract and its effect on repeat instability. To do this, we used a well-characterized site-specific replication fork barrier (RFB) system in fission yeast that creates an inducible and highly efficient stall that is known to restart by recombination-dependent replication (RDR), in combination with long CAG repeat tracts inserted at various distances and orientations with respect to the RFB. We find that replication by the restarted fork exhibits low fidelity through repeat sequences placed 2-7 kb from the RFB, exhibiting elevated levels of Rad52- and Rad8ScRad5/HsHLTF-dependent instability. CAG expansions and contractions are not elevated to the same degree when the tract is just in front or behind the barrier, suggesting that the long-traveling Polδ-Polδ restarted fork, rather than fork reversal or initial D-loop synthesis through the repeat during stalling and restart, is the greatest source of repeat instability. The switch in replication direction that occurs due to replication from a converging fork while the stalled fork is held at the barrier is also a significant contributor to the repeat instability profile. Our results shed light on a long-standing question of how fork stalling and RDR contribute to expansions and contractions of structure-forming trinucleotide repeats, and reveal that tolerance to replication stress by fork restart comes at the cost of increased instability of repetitive sequences.
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Affiliation(s)
- Michaela A. Gold
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Jenna M. Whalen
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Karine Freon
- Institut Curie, Université PSL, Orsay, France
- Université Paris-Saclay, Orsay, France
| | - Zixin Hong
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Ismail Iraqui
- Institut Curie, Université PSL, Orsay, France
- Université Paris-Saclay, Orsay, France
| | - Sarah A. E. Lambert
- Institut Curie, Université PSL, Orsay, France
- Université Paris-Saclay, Orsay, France
- Equipes Labélisées Ligue Nationale Contre Le Cancer, Orsay, France
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43
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Paul BD. Signaling Overlap between the Golgi Stress Response and Cysteine Metabolism in Huntington's Disease. Antioxidants (Basel) 2021; 10:antiox10091468. [PMID: 34573100 PMCID: PMC8465517 DOI: 10.3390/antiox10091468] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/01/2021] [Accepted: 09/10/2021] [Indexed: 11/29/2022] Open
Abstract
Huntington's disease (HD) is caused by expansion of polyglutamine repeats in the protein huntingtin, which affects the corpus striatum of the brain. The polyglutamine repeats in mutant huntingtin cause its aggregation and elicit toxicity by affecting several cellular processes, which include dysregulated organellar stress responses. The Golgi apparatus not only plays key roles in the transport, processing, and targeting of proteins, but also functions as a sensor of stress, signaling through the Golgi stress response. Unlike the endoplasmic reticulum (ER) stress response, the Golgi stress response is relatively unexplored. This review focuses on the molecular mechanisms underlying the Golgi stress response and its intersection with cysteine metabolism in HD.
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Affiliation(s)
- Bindu D. Paul
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA;
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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44
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Kacher R, Lejeune FX, Noël S, Cazeneuve C, Brice A, Humbert S, Durr A. Propensity for somatic expansion increases over the course of life in Huntington disease. eLife 2021; 10:64674. [PMID: 33983118 PMCID: PMC8118653 DOI: 10.7554/elife.64674] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 04/27/2021] [Indexed: 12/03/2022] Open
Abstract
Recent work on Huntington disease (HD) suggests that somatic instability of CAG repeat tracts, which can expand into the hundreds in neurons, explains clinical outcomes better than the length of the inherited allele. Here, we measured somatic expansion in blood samples collected from the same 50 HD mutation carriers over a twenty-year period, along with post-mortem tissue from 15 adults and 7 fetal mutation carriers, to examine somatic expansions at different stages of life. Post-mortem brains, as previously reported, had the greatest expansions, but fetal cortex had virtually none. Somatic instability in blood increased with age, despite blood cells being short-lived compared to neurons, and was driven mostly by CAG repeat length, then by age at sampling and by interaction between these two variables. Expansion rates were higher in symptomatic subjects. These data lend support to a previously proposed computational model of somatic instability-driven disease.
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Affiliation(s)
- Radhia Kacher
- Sorbonne Université, Paris Brain Institute (ICM Institut du Cerveau), AP-HP, INSERM, CNRS, University Hospital Pitié-Salpêtrière, Paris, France.,Univ. Grenoble Alpes, INSERM, U 1216, Grenoble Institut Neurosciences, Grenoble, France
| | - François-Xavier Lejeune
- Sorbonne Université, Paris Brain Institute (ICM Institut du Cerveau), AP-HP, INSERM, CNRS, University Hospital Pitié-Salpêtrière, Paris, France.,Paris Brain Institute's Data and Analysis Core, University Hospital Pitié-Salpêtrière, Paris, France
| | - Sandrine Noël
- Neurogenetics Laboratory, Department of Genetics, Assistance Publique-Hôpitaux de Paris, University Hospital Pitié-Salpêtrière, Paris, France
| | - Cécile Cazeneuve
- Neurogenetics Laboratory, Department of Genetics, Assistance Publique-Hôpitaux de Paris, University Hospital Pitié-Salpêtrière, Paris, France
| | - Alexis Brice
- Sorbonne Université, Paris Brain Institute (ICM Institut du Cerveau), AP-HP, INSERM, CNRS, University Hospital Pitié-Salpêtrière, Paris, France
| | - Sandrine Humbert
- Univ. Grenoble Alpes, INSERM, U 1216, Grenoble Institut Neurosciences, Grenoble, France
| | - Alexandra Durr
- Sorbonne Université, Paris Brain Institute (ICM Institut du Cerveau), AP-HP, INSERM, CNRS, University Hospital Pitié-Salpêtrière, Paris, France.,Neurogenetics Laboratory, Department of Genetics, Assistance Publique-Hôpitaux de Paris, University Hospital Pitié-Salpêtrière, Paris, France
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45
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Benn CL, Gibson KR, Reynolds DS. Drugging DNA Damage Repair Pathways for Trinucleotide Repeat Expansion Diseases. J Huntingtons Dis 2021; 10:203-220. [PMID: 32925081 PMCID: PMC7990437 DOI: 10.3233/jhd-200421] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
DNA damage repair (DDR) mechanisms have been implicated in a number of neurodegenerative diseases (both genetically determined and sporadic). Consistent with this, recent genome-wide association studies in Huntington’s disease (HD) and other trinucleotide repeat expansion diseases have highlighted genes involved in DDR mechanisms as modifiers for age of onset, rate of progression and somatic instability. At least some clinical genetic modifiers have been shown to have a role in modulating trinucleotide repeat expansion biology and could therefore provide new disease-modifying therapeutic targets. In this review, we focus on key considerations with respect to drug discovery and development using DDR mechanisms as a target for trinucleotide repeat expansion diseases. Six areas are covered with specific reference to DDR and HD: 1) Target identification and validation; 2) Candidate selection including therapeutic modality and delivery; 3) Target drug exposure with particular focus on blood-brain barrier penetration, engagement and expression of pharmacology; 4) Safety; 5) Preclinical models as predictors of therapeutic efficacy; 6) Clinical outcome measures including biomarkers.
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Affiliation(s)
- Caroline L Benn
- LoQus23 Therapeutics, Riverside, Babraham Research Campus, Cambridge, UK
| | - Karl R Gibson
- Sandexis Medicinal Chemistry Ltd, Innovation House, Discovery Park, Sandwich, Kent, UK
| | - David S Reynolds
- LoQus23 Therapeutics, Riverside, Babraham Research Campus, Cambridge, UK
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46
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Jones L, Wheeler VC, Pearson CE. Special Issue: DNA Repair and Somatic Repeat Expansion in Huntington's Disease. J Huntingtons Dis 2021; 10:3-5. [PMID: 33554921 PMCID: PMC7990429 DOI: 10.3233/jhd-219001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Lesley Jones
- Division of Psychological Medicine and Clinical Neurosciences, MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - 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
| | - Christopher E Pearson
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada.,University of Toronto, Program of Molecular Genetics
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47
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Monckton DG. The Contribution of Somatic Expansion of the CAG Repeat to Symptomatic Development in Huntington's Disease: A Historical Perspective. J Huntingtons Dis 2021; 10:7-33. [PMID: 33579863 PMCID: PMC7990401 DOI: 10.3233/jhd-200429] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The discovery in the early 1990s of the expansion of unstable simple sequence repeats as the causative mutation for a number of inherited human disorders, including Huntington's disease (HD), opened up a new era of human genetics and provided explanations for some old problems. In particular, an inverse association between the number of repeats inherited and age at onset, and unprecedented levels of germline instability, biased toward further expansion, provided an explanation for the wide symptomatic variability and anticipation observed in HD and many of these disorders. The repeats were also revealed to be somatically unstable in a process that is expansion-biased, age-dependent and tissue-specific, features that are now increasingly recognised as contributory to the age-dependence, progressive nature and tissue specificity of the symptoms of HD, and at least some related disorders. With much of the data deriving from affected individuals, and model systems, somatic expansions have been revealed to arise in a cell division-independent manner in critical target tissues via a mechanism involving key components of the DNA mismatch repair pathway. These insights have opened new approaches to thinking about how the disease could be treated by suppressing somatic expansion and revealed novel protein targets for intervention. Exciting times lie ahead in turning these insights into novel therapies for HD and related disorders.
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Affiliation(s)
- Darren G. Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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48
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Ciosi M, Cumming SA, Chatzi A, Larson E, Tottey W, Lomeikaite V, Hamilton G, Wheeler VC, Pinto RM, Kwak S, Morton AJ, Monckton DG. Approaches to Sequence the HTT CAG Repeat Expansion and Quantify Repeat Length Variation. J Huntingtons Dis 2021; 10:53-74. [PMID: 33579864 PMCID: PMC7990409 DOI: 10.3233/jhd-200433] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the expansion of the HTT CAG repeat. Affected individuals inherit ≥36 repeats and longer alleles cause earlier onset, greater disease severity and faster disease progression. The HTT CAG repeat is genetically unstable in the soma in a process that preferentially generates somatic expansions, the proportion of which is associated with disease onset, severity and progression. Somatic mosaicism of the HTT CAG repeat has traditionally been assessed by semi-quantitative PCR-electrophoresis approaches that have limitations (e.g., no information about sequence variants). Genotyping-by-sequencing could allow for some of these limitations to be overcome. OBJECTIVE To investigate the utility of PCR sequencing to genotype large (>50 CAGs) HD alleles and to quantify the associated somatic mosaicism. METHODS We have applied MiSeq and PacBio sequencing to PCR products of the HTT CAG repeat in transgenic R6/2 mice carrying ∼55, ∼110, ∼255 and ∼470 CAGs. For each of these alleles, we compared the repeat length distributions generated for different tissues at two ages. RESULTS We were able to sequence the CAG repeat full length in all samples. However, the repeat length distributions for samples with ∼470 CAGs were biased towards shorter repeat lengths. CONCLUSION PCR sequencing can be used to sequence all the HD alleles considered, but this approach cannot be used to estimate modal allele size or quantify somatic expansions for alleles ⪢250 CAGs. We review the limitations of PCR sequencing and alternative approaches that may allow the quantification of somatic contractions and very large somatic expansions.
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Affiliation(s)
- Marc Ciosi
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Sarah A. Cumming
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Afroditi Chatzi
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Eloise Larson
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - William Tottey
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Vilija Lomeikaite
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Graham Hamilton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- Glasgow Polyomics, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - 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
| | - Ricardo Mouro Pinto
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Seung Kwak
- CHDI Management/CHDI Foundation, Princeton, NJ, USA
| | - A. Jennifer Morton
- Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge, UK
| | - Darren G. Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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Deshmukh AL, Porro A, Mohiuddin M, Lanni S, Panigrahi GB, Caron MC, Masson JY, Sartori AA, Pearson CE. FAN1, a DNA Repair Nuclease, as a Modifier of Repeat Expansion Disorders. J Huntingtons Dis 2021; 10:95-122. [PMID: 33579867 PMCID: PMC7990447 DOI: 10.3233/jhd-200448] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
FAN1 encodes a DNA repair nuclease. Genetic deficiencies, copy number variants, and single nucleotide variants of FAN1 have been linked to karyomegalic interstitial nephritis, 15q13.3 microdeletion/microduplication syndrome (autism, schizophrenia, and epilepsy), cancer, and most recently repeat expansion diseases. For seven CAG repeat expansion diseases (Huntington's disease (HD) and certain spinocerebellar ataxias), modification of age of onset is linked to variants of specific DNA repair proteins. FAN1 variants are the strongest modifiers. Non-coding disease-delaying FAN1 variants and coding disease-hastening variants (p.R507H and p.R377W) are known, where the former may lead to increased FAN1 levels and the latter have unknown effects upon FAN1 functions. Current thoughts are that ongoing repeat expansions in disease-vulnerable tissues, as individuals age, promote disease onset. Fan1 is required to suppress against high levels of ongoing somatic CAG and CGG repeat expansions in tissues of HD and FMR1 transgenic mice respectively, in addition to participating in DNA interstrand crosslink repair. FAN1 is also a modifier of autism, schizophrenia, and epilepsy. Coupled with the association of these diseases with repeat expansions, this suggests a common mechanism, by which FAN1 modifies repeat diseases. Yet how any of the FAN1 variants modify disease is unknown. Here, we review FAN1 variants, associated clinical effects, protein structure, and the enzyme's attributed functional roles. We highlight how variants may alter its activities in DNA damage response and/or repeat instability. A thorough awareness of the FAN1 gene and FAN1 protein functions will reveal if and how it may be targeted for clinical benefit.
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Affiliation(s)
- Amit L. Deshmukh
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
| | - Antonio Porro
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Mohiuddin Mohiuddin
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
| | - Stella Lanni
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
| | - Gagan B. Panigrahi
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
| | - Marie-Christine Caron
- Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, Québec City, Quebec, Canada
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, Québec City, Quebec, Canada
| | - Jean-Yves Masson
- Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, Québec City, Quebec, Canada
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, Québec City, Quebec, Canada
| | | | - Christopher E. Pearson
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada
- University of Toronto, Program of Molecular Genetics, Toronto, Ontario, Canada
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