51
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Cyclic GMP-AMP synthase promotes the inflammatory and autophagy responses in Huntington disease. Proc Natl Acad Sci U S A 2020; 117:15989-15999. [PMID: 32581130 PMCID: PMC7354937 DOI: 10.1073/pnas.2002144117] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Huntington disease (HD) is a genetic disorder caused by glutamine-expansion in the huntingtin (mHTT) protein, which affects motor, psychiatric, and cognitive function, but the mechanisms remain unclear. mHTT is known to induce DNA damage and affect autophagy, both associated with inflammatory responses, but what mediates all these were unknown. Here we report that cGAS, a DNA damage sensor, is highly upregulated in the striatum of a mouse model and HD human patient’s tissue. We found ribosomes, which make proteins, are robustly accumulated on the cGAS mRNA in HD cells. cGAS depletion decreases—and cGAS expression increases—both inflammatory and autophagy responses in HD striatal cells. Thus, cGAS is a therapeutic target for HD. Blocking cGAS will prevent/slow down HD symptoms. Huntington disease (HD) is caused by an expansion mutation of the N-terminal polyglutamine of huntingtin (mHTT). mHTT is ubiquitously present, but it induces noticeable damage to the brain’s striatum, thereby affecting motor, psychiatric, and cognitive functions. The striatal damage and progression of HD are associated with the inflammatory response; however, the underlying molecular mechanisms remain unclear. Here, we report that cGMP-AMP synthase (cGAS), a DNA sensor, is a critical regulator of inflammatory and autophagy responses in HD. Ribosome profiling revealed that the cGAS mRNA has high ribosome occupancy at exon 1 and codon-specific pauses at positions 171 (CCG) and 172 (CGT) in HD striatal cells. Moreover, the protein levels and activity of cGAS (based on the phosphorylated STING and phosphorylated TBK1 levels), and the expression and ribosome occupancy of cGAS-dependent inflammatory genes (Ccl5 and Cxcl10) are increased in HD striatum. Depletion of cGAS diminishes cGAS activity and decreases the expression of inflammatory genes while suppressing the up-regulation of autophagy in HD cells. In contrast, reinstating cGAS in cGAS-depleted HD cells activates cGAS activity and promotes inflammatory and autophagy responses. Ribosome profiling also revealed that LC3A and LC3B, the two major autophagy initiators, show altered ribosome occupancy in HD cells. We also detected the presence of numerous micronuclei, which are known to induce cGAS, in the cytoplasm of neurons derived from human HD embryonic stem cells. Collectively, our results indicate that cGAS is up-regulated in HD and mediates inflammatory and autophagy responses. Thus, targeting the cGAS pathway may offer therapeutic benefits in HD.
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52
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Wild EJ, Tabrizi SJ. One decade ago, one decade ahead in huntington's disease. Mov Disord 2020; 34:1434-1439. [PMID: 31769087 DOI: 10.1002/mds.27849] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/13/2019] [Accepted: 08/18/2019] [Indexed: 12/15/2022] Open
Affiliation(s)
- Edward J Wild
- UCL Huntington's Disease Centre, Queen Square Institute of Neurology, London, UK
| | - Sarah J Tabrizi
- UCL Huntington's Disease Centre, Queen Square Institute of Neurology, London, UK
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53
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Lee D, Lee YI, Lee YS, Lee SB. The Mechanisms of Nuclear Proteotoxicity in Polyglutamine Spinocerebellar Ataxias. Front Neurosci 2020; 14:489. [PMID: 32581673 PMCID: PMC7289180 DOI: 10.3389/fnins.2020.00489] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 04/20/2020] [Indexed: 12/29/2022] Open
Abstract
Polyglutamine (polyQ) spinocerebellar ataxias (SCAs) are the most prevalent subset of SCAs and share the aberrant expansion of Q-encoding CAG repeats within the coding sequences of disease-responsible genes as their common genetic cause. These polyQ SCAs (SCA1, SCA2, SCA3, SCA6, SCA7, and SCA17) are inherited neurodegenerative diseases characterized by the progressive atrophy of the cerebellum and connected regions of the nervous system, which leads to loss of fine muscle movement coordination. Upon the expansion of polyQ repeats, the mutated proteins typically accumulate disproportionately in the neuronal nucleus, where they sequester various target molecules, including transcription factors and other nuclear proteins. However, it is not yet clearly understood how CAG repeat expansion takes place or how expanded polyQ proteins accumulate in the nucleus. In this article, we review the current knowledge on the molecular and cellular bases of nuclear proteotoxicity of polyQ proteins in SCAs and present our perspectives on the remaining issues surrounding these diseases.
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Affiliation(s)
- Davin Lee
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, South Korea
| | - Yun-Il Lee
- Well Aging Research Center, Division of Biotechnology, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Young-Sam Lee
- Well Aging Research Center, Division of Biotechnology, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea.,Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Sung Bae Lee
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, South Korea
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54
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Xu P, Pan F, Roland C, Sagui C, Weninger K. Dynamics of strand slippage in DNA hairpins formed by CAG repeats: roles of sequence parity and trinucleotide interrupts. Nucleic Acids Res 2020; 48:2232-2245. [PMID: 31974547 PMCID: PMC7049705 DOI: 10.1093/nar/gkaa036] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 12/11/2019] [Accepted: 01/15/2020] [Indexed: 01/08/2023] Open
Abstract
DNA trinucleotide repeats (TRs) can exhibit dynamic expansions by integer numbers of trinucleotides that lead to neurodegenerative disorders. Strand slipped hairpins during DNA replication, repair and/or recombination may contribute to TR expansion. Here, we combine single-molecule FRET experiments and molecular dynamics studies to elucidate slipping dynamics and conformations of (CAG)n TR hairpins. We directly resolve slipping by predominantly two CAG units. The slipping kinetics depends on the even/odd repeat parity. The populated states suggest greater stability for 5′-AGCA-3′ tetraloops, compared with alternative 5′-CAG-3′ triloops. To accommodate the tetraloop, even(odd)-numbered repeats have an even(odd) number of hanging bases in the hairpin stem. In particular, a paired-end tetraloop (no hanging TR) is stable in (CAG)n = even, but such situation cannot occur in (CAG)n = odd, where the hairpin is “frustrated’’ and slips back and forth between states with one TR hanging at the 5′ or 3′ end. Trinucleotide interrupts in the repeating CAG pattern associated with altered disease phenotypes select for specific conformers with favorable loop sequences. Molecular dynamics provide atomic-level insight into the loop configurations. Reducing strand slipping in TR hairpins by sequence interruptions at the loop suggests disease-associated variations impact expansion mechanisms at the level of slipped hairpins.
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Affiliation(s)
- Pengning Xu
- Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
| | - Feng Pan
- Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
| | - Christopher Roland
- Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
| | - Celeste Sagui
- Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
| | - Keith Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
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55
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McLoughlin HS, Moore LR, Paulson HL. Pathogenesis of SCA3 and implications for other polyglutamine diseases. Neurobiol Dis 2020; 134:104635. [PMID: 31669734 PMCID: PMC6980715 DOI: 10.1016/j.nbd.2019.104635] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 09/30/2019] [Accepted: 10/03/2019] [Indexed: 12/14/2022] Open
Abstract
Tandem repeat diseases include the neurodegenerative disorders known as polyglutamine (polyQ) diseases, caused by CAG repeat expansions in the coding regions of the respective disease genes. The nine known polyQ disease include Huntington's disease (HD), dentatorubral-pallidoluysian atrophy (DRPLA), spinal bulbar muscular atrophy (SBMA), and six spinocerebellar ataxias (SCA1, SCA2, SCA3, SCA6, SCA7, and SCA17). The underlying disease mechanism in the polyQ diseases is thought principally to reflect dominant toxic properties of the disease proteins which, when harboring a polyQ expansion, differentially interact with protein partners and are prone to aggregate. Among the polyQ diseases, SCA3 is the most common SCA, and second to HD in prevalence worldwide. Here we summarize current understanding of SCA3 disease mechanisms within the broader context of the broader polyQ disease field. We emphasize properties of the disease protein, ATXN3, and new discoveries regarding three potential pathogenic mechanisms: 1) altered protein homeostasis; 2) DNA damage and dysfunctional DNA repair; and 3) nonneuronal contributions to disease. We conclude with an overview of the therapeutic implications of recent mechanistic insights.
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Affiliation(s)
| | - Lauren R Moore
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
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56
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Kawaguchi T, Rollins MG, Moinpour M, Morera AA, Ebmeier CC, Old WM, Schwartz JC. Changes to the TDP-43 and FUS Interactomes Induced by DNA Damage. J Proteome Res 2020; 19:360-370. [PMID: 31693373 PMCID: PMC6947635 DOI: 10.1021/acs.jproteome.9b00575] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Indexed: 12/13/2022]
Abstract
The RNA-binding proteins TDP-43 and FUS are tied as the third leading known genetic cause for amyotrophic lateral sclerosis (ALS), and TDP-43 proteopathies are found in nearly all ALS patients. Both the natural function and contribution to pathology for TDP-43 remain unclear. The intersection of functions between TDP-43 and FUS can focus attention for those natural functions mostly likely to be relevant to disease. Here, we compare the role played by TDP-43 and FUS, maintaining chromatin stability for dividing HEK293T cells. We also determine and compare the interactomes of TDP-43 and FUS, quantitating changes in those before and after DNA damage. Finally, selected interactions with known importance to DNA damage repair were validated by co-immunoprecipitation assays. This study uncovered TDP-43 and FUS binding to several factors important to DNA repair mechanisms that can be replication-dependent, -independent, or both. These results provide further evidence that TDP-43 has an important role in DNA stability and provide new ways that TDP-43 can bind to the machinery that guards DNA integrity in cells.
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Affiliation(s)
- Tetsuya Kawaguchi
- Department
of Chemistry and Biochemistry and Department of Molecular and Cellular
Biology, University of Arizona, Tucson, Arizona 85721, United States
| | - Matthew G. Rollins
- Department
of Chemistry and Biochemistry and Department of Molecular and Cellular
Biology, University of Arizona, Tucson, Arizona 85721, United States
| | - Mahta Moinpour
- Department
of Chemistry and Biochemistry and Department of Molecular and Cellular
Biology, University of Arizona, Tucson, Arizona 85721, United States
| | - Andres A. Morera
- Department
of Chemistry and Biochemistry and Department of Molecular and Cellular
Biology, University of Arizona, Tucson, Arizona 85721, United States
| | - Christopher C. Ebmeier
- Department
of Molecular and Cellular Biology, University
of Colorado, Boulder, Colorado 80309, United States
| | - William M. Old
- Department
of Molecular and Cellular Biology, University
of Colorado, Boulder, Colorado 80309, United States
| | - Jacob C. Schwartz
- Department
of Chemistry and Biochemistry and Department of Molecular and Cellular
Biology, University of Arizona, Tucson, Arizona 85721, United States
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57
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Cinesi C, Yang B, Dion V. GFP Reporters to Monitor Instability and Expression of Expanded CAG/CTG Repeats. Methods Mol Biol 2020; 2056:255-268. [PMID: 31586353 DOI: 10.1007/978-1-4939-9784-8_16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Expanded CAG/CTG repeats are genetically unstable and, upon expression, cause neurological and neuromuscular diseases. The molecular mechanisms of repeat instability and expression remain poorly understood despite their importance for the pathogenesis of a family of 14 devastating human diseases. This is in part because conventional assays are tedious and time-consuming. Recently, however, GFP-based reporters have been designed to provide a rapid and reliable means of assessing these parameters. Here we provide protocols for quantifying repeat instability and expression using a GFP-based chromosomal reporter and the newly developed ParB/ANCHOR-mediated Inducible Targeting (PInT) and how to validate the results.
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Affiliation(s)
- Cinzia Cinesi
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Bin Yang
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Vincent Dion
- Dementia Research Institute, Cardiff University, Cardiff, UK.
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58
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Thadathil N, Hori R, Xiao J, Khan MM. DNA double-strand breaks: a potential therapeutic target for neurodegenerative diseases. Chromosome Res 2019; 27:345-364. [PMID: 31707536 PMCID: PMC7934912 DOI: 10.1007/s10577-019-09617-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/08/2019] [Accepted: 09/16/2019] [Indexed: 12/13/2022]
Abstract
The complexity of neurodegeneration restricts the ability to understand and treat the neurological disorders affecting millions of people worldwide. Therefore, there is an unmet need to develop new and more effective therapeutic strategies to combat these devastating conditions and that will only be achieved with a better understanding of the biological mechanism associated with disease conditions. Recent studies highlight the role of DNA damage, particularly, DNA double-strand breaks (DSBs), in the progression of neuronal loss in a broad spectrum of human neurodegenerative diseases. This is not unexpected because neurons are prone to DNA damage due to their non-proliferative nature and high metabolic activity. However, it is not clear if DSBs is a primary driver of neuronal loss in disease conditions or simply occurs concomitant with disease progression. Here, we provide evidence that supports a critical role of DSBs in the pathogenesis of the neurodegenerative diseases. Among different kinds of DNA damages, DSBs are the most harmful and perilous type of DNA damage and can lead to cell death if left unrepaired or repaired with error. In this review, we explore the current state of knowledge regarding the role of DSBs repair mechanisms in preserving neuronal function and survival and describe how DSBs could drive the molecular mechanisms resulting in neuronal death in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. We also discuss the potential implications of DSBs as a novel therapeutic target and prognostic marker in patients with neurodegenerative conditions.
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Affiliation(s)
- Nidheesh Thadathil
- Department of Neurology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38163, USA
| | - Roderick Hori
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jianfeng Xiao
- Department of Neurology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38163, USA
| | - Mohammad Moshahid Khan
- Department of Neurology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38163, USA.
- Division of Rehabilitation Sciences and Department of Physical Therapy, College of Health Professions, University of Tennessee Health Science Center, Memphis, TN, USA.
- Department of Neurology, University of Tennessee Health Science Center, Memphis, TN, 38163, USA.
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59
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Egorova PA, Bezprozvanny IB. Molecular Mechanisms and Therapeutics for Spinocerebellar Ataxia Type 2. Neurotherapeutics 2019; 16:1050-1073. [PMID: 31435879 PMCID: PMC6985344 DOI: 10.1007/s13311-019-00777-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The effective therapeutic treatment and the disease-modifying therapy for spinocerebellar ataxia type 2 (SCA2) (a progressive hereditary disease caused by an expansion of polyglutamine in the ataxin-2 protein) is not available yet. At present, only symptomatic treatment and methods of palliative care are prescribed to the patients. Many attempts were made to study the physiological, molecular, and biochemical changes in SCA2 patients and in a variety of the model systems to find new therapeutic targets for SCA2 treatment. A better understanding of the uncovered molecular mechanisms of the disease allowed the scientific community to develop strategies of potential therapy and helped to create some promising therapeutic approaches for SCA2 treatment. Recent progress in this field will be discussed in this review article.
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Affiliation(s)
- Polina A Egorova
- Laboratory of Molecular Neurodegeneration, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, 195251, Russia
| | - Ilya B Bezprozvanny
- Laboratory of Molecular Neurodegeneration, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, 195251, Russia.
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, ND12.200, Dallas, Texas, 75390, USA.
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60
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Tber Z, Biteau NG, Agrofoglio L, Cros J, Goffinont S, Castaing B, Nicolas C, Roy V. Microwave-Assisted Suzuki-Miyaura and Sonogashira Coupling of 4-Chloro-2-(trifluoromethyl)pyrido[1,2- e
]purine Derivatives. European J Org Chem 2019. [DOI: 10.1002/ejoc.201900921] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Zahira Tber
- Institut de Chimie Organique et Analytique, UMR CNRS 7311; Université d'Orléans; Rue de Chartres - BP 6759, 45067 Orléans cedex 2 France
| | - Nicolas G. Biteau
- Institut de Chimie Organique et Analytique, UMR CNRS 7311; Université d'Orléans; Rue de Chartres - BP 6759, 45067 Orléans cedex 2 France
| | - Luigi Agrofoglio
- Institut de Chimie Organique et Analytique, UMR CNRS 7311; Université d'Orléans; Rue de Chartres - BP 6759, 45067 Orléans cedex 2 France
| | - Julien Cros
- Centre de Biophysique Moléculaire; 45072 Orléans France
| | | | | | - Cyril Nicolas
- Institut de Chimie Organique et Analytique, UMR CNRS 7311; Université d'Orléans; Rue de Chartres - BP 6759, 45067 Orléans cedex 2 France
| | - Vincent Roy
- Institut de Chimie Organique et Analytique, UMR CNRS 7311; Université d'Orléans; Rue de Chartres - BP 6759, 45067 Orléans cedex 2 France
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61
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DNA repair and neurological disease: From molecular understanding to the development of diagnostics and model organisms. DNA Repair (Amst) 2019; 81:102669. [PMID: 31331820 DOI: 10.1016/j.dnarep.2019.102669] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In both replicating and non-replicating cells, the maintenance of genomic stability is of utmost importance. Dividing cells can repair DNA damage during cell division, tolerate the damage by employing potentially mutagenic DNA polymerases or die via apoptosis. However, the options for accurate DNA repair are more limited in non-replicating neuronal cells. If DNA damage is left unresolved, neuronal cells die causing neurodegenerative disorders. A number of pathogenic variants of DNA repair proteins have been linked to multiple neurological diseases. The current challenge is to harness our knowledge of fundamental properties of DNA repair to improve diagnosis, prognosis and treatment of such debilitating disorders. In this perspective, we will focus on recent efforts in identifying novel DNA repair biomarkers for the diagnosis of neurological disorders and their use in monitoring the patient response to therapy. These efforts are greatly facilitated by the development of model organisms such as zebrafish, which will also be summarised.
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62
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Genome-wide investigation of microsatellite polymorphism in coding region of the giant panda (Ailuropoda melanoleuca) genome: a resource for study of phenotype diversity and abnormal traits. MAMMAL RES 2019. [DOI: 10.1007/s13364-019-00418-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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63
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Warmerdam DO, Wolthuis RMF. Keeping ribosomal DNA intact: a repeating challenge. Chromosome Res 2018; 27:57-72. [PMID: 30556094 PMCID: PMC6394564 DOI: 10.1007/s10577-018-9594-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 11/20/2018] [Accepted: 11/29/2018] [Indexed: 02/06/2023]
Abstract
More than half of the human genome consists of repetitive sequences, with the ribosomal DNA (rDNA) representing two of the largest repeats. Repetitive rDNA sequences may form a threat to genomic integrity and cellular homeostasis due to the challenging aspects of their transcription, replication, and repair. Predisposition to cancer, premature aging, and neurological impairment in ataxia-telangiectasia and Bloom syndrome, for instance, coincide with increased cellular rDNA repeat instability. However, the mechanisms by which rDNA instability contributes to these hereditary syndromes and tumorigenesis remain unknown. Here, we review how cells govern rDNA stability and how rDNA break repair influences expansion and contraction of repeat length, a process likely associated with human disease. Recent advancements in CRISPR-based genome engineering may help to explain how cells keep their rDNA intact in the near future.
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Affiliation(s)
- Daniël O Warmerdam
- CRISPR Platform, University of Amsterdam, Cancer Center Amsterdam, Amsterdam UMC, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands.
| | - Rob M F Wolthuis
- Section of Oncogenetics, Department of Clinical Genetics, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam UMC, de Boelelaan 1117, 1081 HV, Amsterdam, the Netherlands
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64
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Maiuri T, Bowie LE, Truant R. DNA Repair Signaling of Huntingtin: The Next Link Between Late-Onset Neurodegenerative Disease and Oxidative DNA Damage. DNA Cell Biol 2018; 38:1-6. [PMID: 30481056 DOI: 10.1089/dna.2018.4476] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
A new hypothesis for the mechanism of Huntington's disease (HD) is driven by a small molecule lead that may connect age-associated reactive oxygen stress, oxidative DNA damage, and mitochondrial dysfunction. These pathways have also recently been defined in genome-wide association studies of cytosine-adenine-guanine-expansion polyglutamine neurodegenerative diseases, including HD and the spinocerebellar ataxias. We discuss how N6-furfuryladenine (N6FFA) nucleotide salvage and role as a kinase neosubstrate may have important mechanistic implications for both HD and familial Parkinson's disease. N6FFA highlights a mechanism of how energy dysregulation and protein misfolding in neurodegeneration may be the effect of age-associated reactive oxygen species damage to DNA and part of a feedback loop augmenting with aging.
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Affiliation(s)
- Tamara Maiuri
- Department of Biochemistry and Biomedical Sciences, McMaster University , Hamilton, Canada
| | - Laura E Bowie
- Department of Biochemistry and Biomedical Sciences, McMaster University , Hamilton, Canada
| | - Ray Truant
- Department of Biochemistry and Biomedical Sciences, McMaster University , Hamilton, Canada
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65
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Yau WY, O'Connor E, Sullivan R, Akijian L, Wood NW. DNA repair in trinucleotide repeat ataxias. FEBS J 2018; 285:3669-3682. [PMID: 30152109 DOI: 10.1111/febs.14644] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/15/2018] [Accepted: 08/23/2018] [Indexed: 12/21/2022]
Abstract
The inherited cerebellar ataxias comprise of a genetic heterogeneous group of disorders. Pathogenic expansions of cytosine-adenine-guanine (CAG) encoding polyglutamine tracts account for the largest proportion of autosomal dominant cerebellar ataxias, while GAA expansion in the first introns of frataxin gene is the commonest cause of autosomal recessive cerebellar ataxias. Currently, there is no available treatment to alter the disease trajectory, with devastating consequences for affected individuals. Inter- and Intrafamily phenotypic variability suggest the existence of genetic modifiers, which may become targets amendable to treatment. Recent studies have demonstrated the importance of DNA repair pathways in modifying spinocerebellar ataxia with CAG repeat expansions. In this review, we discuss the mechanisms in which DNA repair pathways, epigenetics and other genetic factors may act as modifiers in cerebellar ataxias due to trinucleotide repeat expansions.
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Affiliation(s)
- Wai Yan Yau
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK
| | - Emer O'Connor
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK
| | - Roisin Sullivan
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK
| | - Layan Akijian
- Department of Neurology, The National Hospital for Neurology and Neurosurgery, London, UK
| | - Nicholas W Wood
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK.,Neurogenetics laboratory, The National Hospital for Neurology and Neurosurgery, London, UK
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66
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Accumulation of Mitochondrial DNA Common Deletion Since The Preataxic Stage of Machado-Joseph Disease. Mol Neurobiol 2018; 56:119-124. [PMID: 29679261 DOI: 10.1007/s12035-018-1069-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 04/09/2018] [Indexed: 12/27/2022]
Abstract
Molecular alterations reflecting pathophysiologic changes thought to occur many years before the clinical onset of Machado-Joseph disease (MJD)/spinocerebellar ataxia type 3 (SCA3), a late-onset polyglutamine disorder, remain unidentified. The absence of molecular biomarkers hampers clinical trials, which lack sensitive measures of disease progression, preventing the identification of events occurring prior to clinical onset. Our aim was to analyse the mtDNA content and the amount of the common deletion (m.8482_13460del4977) in a cohort of 16 preataxic MJD mutation carriers, 85 MJD patients and 101 apparently healthy age-matched controls. Relative expression levels of RPPH1, MT-ND1 and MT-ND4 genes were assessed by quantitative real-time PCR. The mtDNA content was calculated as the difference between the expression levels of a mitochondrial gene (MT-ND1) and a nuclear gene (RPPH1); the amount of mtDNA common deletion was calculated as the difference between expression levels of a deleted (MT-ND4) and an undeleted (MT-ND1) mitochondrial genes. mtDNA content in MJD carriers was similar to that of healthy age-matched controls, whereas the percentage of the common deletion was significantly increased in MJD subjects, and more pronounced in the preclinical stage (p < 0.05). The BCL2/BAX ratio was decreased in preataxic carriers compared to controls, suggesting that the mitochondrial-mediated apoptotic pathway is altered in MJD. Our findings demonstrate for the first time that accumulation of common deletion starts in the preclinical stage. Such early alterations provide support to the current understanding that any therapeutic intervention in MJD should start before the overt clinical phenotype.
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