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Sujkowski A, Hong L, Wessells RJ, Todi SV. The protective role of exercise against age-related neurodegeneration. Ageing Res Rev 2022; 74:101543. [PMID: 34923167 PMCID: PMC8761166 DOI: 10.1016/j.arr.2021.101543] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/01/2021] [Accepted: 12/14/2021] [Indexed: 02/08/2023]
Abstract
Endurance exercise is a widely accessible, low-cost intervention with a variety of benefits to multiple organ systems. Exercise improves multiple indices of physical performance and stimulates pronounced health benefits reducing a range of pathologies including metabolic, cardiovascular, and neurodegenerative disorders. Endurance exercise delays brain aging, preserves memory and cognition, and improves symptoms of neurodegenerative pathologies like Amyotrophic Lateral Sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, and various ataxias. Potential mechanisms underlying the beneficial effects of exercise include neuronal survival and plasticity, neurogenesis, epigenetic modifications, angiogenesis, autophagy, and the synthesis and release of neurotrophins and cytokines. In this review, we discuss shared benefits and molecular pathways driving the protective effects of endurance exercise on various neurodegenerative diseases in animal models and in humans.
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Affiliation(s)
- Alyson Sujkowski
- Department of Physiology, Wayne State University School of Medicine, USA; Department of Pharmacology, Wayne State University School of Medicine, USA
| | - Luke Hong
- Department of Pharmacology, Wayne State University School of Medicine, USA; Department of Neurology, Wayne State University School of Medicine, USA
| | - R J Wessells
- Department of Physiology, Wayne State University School of Medicine, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, USA; Department of Neurology, Wayne State University School of Medicine, USA.
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2
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Johnson SL, Libohova K, Blount JR, Sujkowski AL, Prifti MV, Tsou WL, Todi SV. Targeting the VCP-binding motif of ataxin-3 improves phenotypes in Drosophila models of Spinocerebellar Ataxia Type 3. Neurobiol Dis 2021; 160:105516. [PMID: 34563642 PMCID: PMC8693084 DOI: 10.1016/j.nbd.2021.105516] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/23/2021] [Accepted: 09/21/2021] [Indexed: 11/28/2022] Open
Abstract
Of the family of polyglutamine (polyQ) neurodegenerative diseases, Spinocerebellar Ataxia Type 3 (SCA3) is the most common. Like other polyQ diseases, SCA3 stems from abnormal expansions in the CAG triplet repeat of its disease gene resulting in elongated polyQ repeats within its protein, ataxin-3. Various ataxin-3 protein domains contribute to its toxicity, including the valosin-containing protein (VCP)-binding motif (VBM). We previously reported that VCP, a homo-hexameric protein, enhances pathogenic ataxin-3 aggregation and exacerbates its toxicity. These findings led us to explore the impact of targeting the SCA3 protein by utilizing a decoy protein comprising the N-terminus of VCP (N-VCP) that binds ataxin-3's VBM. The notion was that N-VCP would reduce binding of ataxin-3 to VCP, decreasing its aggregation and toxicity. We found that expression of N-VCP in Drosophila melanogaster models of SCA3 ameliorated various phenotypes, coincident with reduced ataxin-3 aggregation. This protective effect was specific to pathogenic ataxin-3 and depended on its VBM. Increasing the amount of N-VCP resulted in further phenotype improvement. Our work highlights the protective potential of targeting the VCP-ataxin-3 interaction in SCA3, a key finding in the search for therapeutic opportunities for this incurable disorder.
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Affiliation(s)
- Sean L Johnson
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Jessica R Blount
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Alyson L Sujkowski
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Matthew V Prifti
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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3
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Raj K, Akundi RS. Mutant Ataxin-3-Containing Aggregates (MATAGGs) in Spinocerebellar Ataxia Type 3: Dynamics of the Disorder. Mol Neurobiol 2021; 58:3095-3118. [PMID: 33629274 DOI: 10.1007/s12035-021-02314-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: 10/11/2020] [Accepted: 01/25/2021] [Indexed: 11/25/2022]
Abstract
Spinocerebellar ataxia type 3 (SCA3) is the most common type of SCA worldwide caused by abnormal polyglutamine expansion in the coding region of the ataxin-3 gene. Ataxin-3 is a multi-faceted protein involved in various cellular processes such as deubiquitination, cytoskeletal organisation, and transcriptional regulation. The presence of an expanded poly(Q) stretch leads to altered processing and misfolding of the protein culminating in the production of insoluble protein aggregates in the cell. Various post-translational modifications affect ataxin-3 fibrillation and aggregation. This review provides an exhaustive assessment of the various pathogenic mechanisms undertaken by the mutant ataxin-3-containing aggregates (MATAGGs) for disease induction and neurodegeneration. This includes in-depth discussion on MATAGG dynamics including their formation, role in neuronal pathogenesis, and the debate over the toxic v/s protective nature of the MATAGGs in disease progression. Additionally, the currently available therapeutic strategies against SCA3 have been reviewed. The shift in the focus of such strategies, from targeting the steps that lead to or reduce aggregate formation to targeting the expression of mutant ataxin-3 itself via RNA-based therapeutics, has also been presented. We also discuss the intriguing promise that various growth and neurotrophic factors, especially the insulin pathway, hold in the modulation of SCA3 progression. These emerging areas show the newer directions through which SCA3 can be targeted including various preclinical and clinical trials. All these advances made in the last three decades since the discovery of the ataxin-3 gene have been critically reviewed here.
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Affiliation(s)
- Kritika Raj
- Neuroinflammation Research Lab, Faculty of Life Sciences and Biotechnology, South Asian University, Chanakyapuri, New Delhi, 110021, India
| | - Ravi Shankar Akundi
- Neuroinflammation Research Lab, Faculty of Life Sciences and Biotechnology, South Asian University, Chanakyapuri, New Delhi, 110021, India.
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4
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Sena LS, Dos Santos Pinheiro J, Saraiva-Pereira ML, Jardim LB. Selective forces acting on spinocerebellar ataxia type 3/Machado-Joseph disease recurrency: A systematic review and meta-analysis. Clin Genet 2020; 99:347-358. [PMID: 33219521 DOI: 10.1111/cge.13888] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/25/2020] [Accepted: 11/17/2020] [Indexed: 12/22/2022]
Abstract
Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a dominant neurodegenerative disease caused by the expansion of a CAG repeat tract in ATXN3. Anticipation and worsening of clinical picture in subsequent generations were repeatedly reported, but there is no indication that SCA3/MJD frequency is changing. Thus, we performed a systematic review and meta-analysis on phenomena with potential effect on SCA3/MJD recurrency in populations: instability of CAG repeat transmissions, anticipation, fitness, and segregation of alleles. Transmission of the mutant allele was associated with an increase of 1.23 CAG repeats in the next generation, and the average change in age at onset showed an anticipation of 7.75 years per generation; but biased recruitments cannot be ruled out. Affected SCA3/MJD individuals had 45% more children than related controls. Transmissions from SCA3/MJD carriers showed that the expanded allele was segregated in 64% of their children. In contrast, transmissions from normal subjects showed that the minor allele was segregated in 54%. The present meta-analysis concluded that there is a segregation distortion favoring the expanded allele, among children of carriers. Therefore, further studies on transmissions and anticipation phenomena as well as more observations about fertility are required to clarify these selective forces over SCA3/MJD.
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Affiliation(s)
- Lucas Schenatto Sena
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Centros de Pesquisa Clínica e Experimental, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Jordânia Dos Santos Pinheiro
- Centros de Pesquisa Clínica e Experimental, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Maria Luiza Saraiva-Pereira
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Centros de Pesquisa Clínica e Experimental, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Instituto de Genética Médica Populacional, Porto Alegre, Brazil
| | - Laura Bannach Jardim
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Centros de Pesquisa Clínica e Experimental, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Instituto de Genética Médica Populacional, Porto Alegre, Brazil.,Departamento de Medicina Interna, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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5
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Souza GN, Kersting N, Krum-Santos AC, Santos ASP, Furtado GV, Pacheco D, Gonçalves TA, Saute JA, Schuler-Faccini L, Mattos EP, Saraiva-Pereira ML, Jardim LB. Spinocerebellar ataxia type 3/Machado-Joseph disease: segregation patterns and factors influencing instability of expanded CAG transmissions. Clin Genet 2016; 90:134-40. [PMID: 26693702 DOI: 10.1111/cge.12719] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 11/30/2022]
Abstract
Controversies about Mendelian segregation and CAG expansion (CAGexp) instabilities during meiosis in spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) need clarification. Additional evidence about these issues was obtained from the cohort of all SCA3/MJD individuals living in South Brazil. A survey was carried out to update information registered since 2001. Deaths were checked with the Public Information System, and data was made anonymous. Anticipation and delta-CAGexp from parent-offspring pairs, and delta-CAGexp between siblings were obtained. One hundred and fifty-nine families (94% of the entire registry) were retrieved, comprising 3725 living individuals as of 2015, 625 of these being symptomatic. Minimal prevalence was 6:100,000. Carriers of a CAGexp represented 65.6% of sibs in the genotyped offspring (p < 0.001). Median instability was larger among paternal than maternal transmissions, and instabilities correlated with anticipation (r = 0.38; p = 0.001). Age of the parent correlated to delta-CAGexp among 115 direct parent-offspring CAGexp transmissions (ρ = 0.23, p = 0.014). In 98 additional kindreds, the delta-CAGexp between 269 siblings correlated with their delta-of-age (ρ = 0.27, p < 0.0001). SCA3/MJD was associated with a segregation distortion favoring the expanded allele in our cohort. Instability of expansion during meiosis was weakly influenced by the age of the transmitting parent at the time of conception.
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Affiliation(s)
- G N Souza
- Programa de Pós-Graduação em Ciências Médicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - N Kersting
- Programa de Pós-Graduação em Ciências Médicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - A C Krum-Santos
- Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - A S P Santos
- Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - G V Furtado
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Laboratório de Identificação Genética, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - D Pacheco
- Faculdade de Serviço Social, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - T A Gonçalves
- Escola de Enfermagem, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - J A Saute
- Laboratório de Identificação Genética, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - L Schuler-Faccini
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Departamento de Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Instituto de Genética Médica Populacional (INAGEMP), Porto Alegre, Brazil
| | - E P Mattos
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Laboratório de Identificação Genética, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - M L Saraiva-Pereira
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Laboratório de Identificação Genética, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Instituto de Genética Médica Populacional (INAGEMP), Porto Alegre, Brazil.,Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - L B Jardim
- Programa de Pós-Graduação em Ciências Médicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Laboratório de Identificação Genética, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Instituto de Genética Médica Populacional (INAGEMP), Porto Alegre, Brazil.,Departamento de Medicina Interna, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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6
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Raposo M, Ramos A, Bettencourt C, Lima M. Replicating studies of genetic modifiers in spinocerebellar ataxia type 3: can homogeneous cohorts aid? Brain 2015; 138:e398. [PMID: 26173860 DOI: 10.1093/brain/awv206] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Mafalda Raposo
- 1 Department of Biology, University of the Azores, Ponta Delgada, Portugal 1 Department of Biology, University of the Azores, Ponta Delgada, Portugal 1 Department of Biology, University of the Azores, Ponta Delgada, Portugal
| | - Amanda Ramos
- 1 Department of Biology, University of the Azores, Ponta Delgada, Portugal 1 Department of Biology, University of the Azores, Ponta Delgada, Portugal 1 Department of Biology, University of the Azores, Ponta Delgada, Portugal
| | | | - Manuela Lima
- 1 Department of Biology, University of the Azores, Ponta Delgada, Portugal 1 Department of Biology, University of the Azores, Ponta Delgada, Portugal 1 Department of Biology, University of the Azores, Ponta Delgada, Portugal
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7
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8
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Liu J, Yu D, Aiba Y, Pendergraff H, Swayze EE, Lima WF, Hu J, Prakash TP, Corey DR. ss-siRNAs allele selectively inhibit ataxin-3 expression: multiple mechanisms for an alternative gene silencing strategy. Nucleic Acids Res 2013; 41:9570-83. [PMID: 23935115 PMCID: PMC3814390 DOI: 10.1093/nar/gkt693] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Single-stranded silencing RNAs (ss-siRNAs) provide an alternative approach to gene silencing. ss-siRNAs combine the simplicity and favorable biodistribution of antisense oligonucleotides with robust silencing through RNA interference (RNAi). Previous studies reported potent and allele-selective inhibition of human huntingtin expression by ss-siRNAs that target the expanded CAG repeats within the mutant allele. Mutant ataxin-3, the genetic cause of Machado-Joseph Disease, also contains an expanded CAG repeat. We demonstrate here that ss-siRNAs are allele-selective inhibitors of ataxin-3 expression and then redesign ss-siRNAs to optimize their selectivity. We find that both RNAi-related and non-RNAi-related mechanisms affect gene expression by either blocking translation or affecting alternative splicing. These results have four broad implications: (i) ss-siRNAs will not always behave similarly to analogous RNA duplexes; (ii) the sequences surrounding CAG repeats affect allele-selectivity of anti-CAG oligonucleotides; (iii) ss-siRNAs can function through multiple mechanisms and; and (iv) it is possible to use chemical modification to optimize ss-siRNA properties and improve their potential for drug discovery.
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Affiliation(s)
- Jing Liu
- Departments of Pharmacology and Biochemistry, UT Southwestern Medical Center at Dallas, Dallas, TX 75390, USA and Department of Medicinal Chemistry and Core Antisense Research, ISIS Pharmaceuticals, Carlsbad, CA 92010, USA
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9
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Abstract
Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), may be the most common dominantly inherited ataxia in the world. Here I will review historical, clinical, neuropathological, genetic, and pathogenic features of MJD, and finish with a brief discussion of present, and possible future, treatment for this currently incurable disorder. Like many other dominantly inherited ataxias, MJD/SCA3 shows remarkable clinical heterogeneity, reflecting the underlying genetic defect: an unstable CAG trinucleotide repeat that varies in size among affected persons. This pathogenic repeat in MJD/SCA3 encodes an expanded tract of the amino acid glutamine in the disease protein, which is known as ataxin-3. MJD/SCA3 is one of nine identified polyglutamine neurodegenerative diseases which share features of pathogenesis centered on protein misfolding and accumulation. The specific properties of MJD/SCA3 and its disease protein are discussed in light of what is known about the entire class of polyglutamine diseases.
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Affiliation(s)
- Henry Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA.
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10
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Hu J, Gagnon KT, Liu J, Watts JK, Syeda-Nawaz J, Bennett CF, Swayze EE, Randolph J, Chattopadhyaya J, Corey DR. Allele-selective inhibition of ataxin-3 (ATX3) expression by antisense oligomers and duplex RNAs. Biol Chem 2011; 392:315-25. [PMID: 21294677 DOI: 10.1515/bc.2011.045] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Spinocerebellar ataxia-3 (also known as Machado-Joseph disease) is an incurable neurodegenerative disorder caused by expression of a mutant variant of ataxin-3 (ATX3) protein. Inhibiting expression of ATX3 would provide a therapeutic strategy, but indiscriminant inhibition of both wild-type and mutant ATX3 might lead to undesirable side effects. An ideal silencing agent would block expression of mutant ATX3 while leaving expression of wild-type ATX3 intact. We have previously observed that peptide nucleic acid (PNA) conjugates targeting the expanded CAG repeat within ATX3 mRNA block expression of both alleles. We have now identified additional PNAs capable of inhibiting ATX3 expression that vary in length and in the nature of the conjugated cation chain. We can also achieve potent and selective inhibition using duplex RNAs containing one or more mismatches relative to the CAG repeat. Anti-CAG antisense bridged nucleic acid oligonucleotides that lack a cationic domain are potent inhibitors but are not allele-selective. Allele-selective inhibitors of ATX3 expression provide insights into the mechanism of selectivity and promising lead compounds for further development and in vivo investigation.
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Affiliation(s)
- Jiaxin Hu
- Departments of Pharmacology and Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390-9041, USA
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11
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Matsuura T. [Molecular and genetic analysis of spinocerebellar ataxia type 10 (SCA10)]. Rinsho Shinkeigaku 2008; 48:1-10. [PMID: 18386626 DOI: 10.5692/clinicalneurol.48.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Spinocerebellar ataxia type 10 (SCA10) is a dominantly inherited neurodegenerative disease caused by expansion of the ATTCT pentanucleotide repeat in intron 9 of a novel gene, ATXN10, on chromosome 22q13.3. It is clinically characterized by progressive ataxia, seizures, and anticipation, which can vary within and between families. The length of the expanded ATTCT repeats is highly unstable on paternal transmission and shows a variable degree of somatic and germline instabilty, revealing complex SCA10 genetic mechanisms. Moreover, the purity of the expanded repeat element may be a disease modifier. ATTCT repeats have been recently shown to form unpaired DNA structure and may serve as an aberrant DNA replication origin, potentially contributing to repeat instability and cell death. How this untranslated ATTCT expansion leads to neurodegeneration has been still controversial. We discuss several possible pathogenic mechanisms for SCA10, and growing number of evidence indicates a gain-of-function RNA mechanism, similar to the myotonic dystrophies caused by non-coding CTG or CCTG repeat expansions.
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Affiliation(s)
- Tohru Matsuura
- Division of Neurogenetics and Bioinformatics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine
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12
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Abstract
Trinucleotide repeat expansions are an important cause of inherited neurodegenerative disease. The expanded repeats are unstable, changing in size when transmitted from parents to offspring (intergenerational instability, "meiotic instability") and often showing size variation within the tissues of an affected individual (somatic mosaicism, "mitotic instability"). Repeat instability is a clinically important phenomenon, as increasing repeat lengths correlate with an earlier age of onset and a more severe disease phenotype. The tendency of expanded trinucleotide repeats to increase in length during their transmission from parent to offspring in these diseases provides a molecular explanation for anticipation (increasing disease severity in successive affected generations). In this review, I explore the genetic and molecular basis of trinucleotide repeat instability. Studies of patients and families with trinucleotide repeat disorders have revealed a number of factors that determine the rate and magnitude of trinucleotide repeat change. Analysis of trinucleotide repeat instability in bacteria, yeast, and mice has yielded additional insights. Despite these advances, the pathways and mechanisms underlying trinucleotide repeat instability in humans remain largely unknown. There are many reasons to suspect that this uniquely human phenomenon will significantly impact upon our understanding of development, differentiation and neurobiology.
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Affiliation(s)
- A R La Spada
- Department of Laboratory Medicine and Pharmacology, University of Washington Medical Center, Seattle 98195, USA.
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13
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Semaka A, Creighton S, Warby S, Hayden MR. Predictive testing for Huntington disease: interpretation and significance of intermediate alleles. Clin Genet 2006; 70:283-94. [PMID: 16965319 DOI: 10.1111/j.1399-0004.2006.00668.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Direct mutation analysis for Huntington disease (HD) became possible in 1993 with the identification of an expanded CAG trinucleotide repeat as the mutation underlying the disease. Expansion of CAG length beyond 35 repeats may be associated with the clinical presentation of HD. HD has never been seen in a person with a CAG size of <36 repeats. Intermediate alleles are defined as being below the affected CAG range but have the potential to expand to >35 CAG repeats within one generation. Thus, children of intermediate allele carriers have a low risk of developing HD. Currently, the intermediate allele range for HD is between 27 and 35 CAG repeats. In this study, we review the current knowledge on intermediate alleles for HD including the CAG repeat range, the intermediate allele frequency, and the clinical implications of an intermediate allele predictive test result. The factors influencing CAG repeat expansion, including the CAG size of the intermediate allele, the sex and age of the transmitting parent, the family history, and the HD gene sequence and haplotype, will also be reviewed.
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Affiliation(s)
- A Semaka
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
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14
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Sasaki H, Yabe I, Yamashita I, Tashiro K. Prevalence of triplet repeat expansion in ataxia patients from Hokkaido, the northernmost island of Japan. J Neurol Sci 2000; 175:45-51. [PMID: 10785256 DOI: 10.1016/s0022-510x(00)00313-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Approximately 44% of cases of spinocerebellar ataxia (SCA) in Hokkaido, the northernmost island of Japan, were estimated to be inherited. To determine the prevalence of triplet repeat expansion in hereditary SCA patients, we genotyped seven genetically defined dominant SCAs in 349 patients, including 266 patients from 77 families, 78 probands from unrelated families with hereditary late-onset SCA, and five patients in whom a family history of SCA was not demonstrated. The frequency of each disorder in a total of 155 unrelated families was 23.9% for Machado-Joseph disease (MJD), 29.0% for SCA6, 9.7% for SCA1, 7.7% for SCA2, and 2.6% for dentatorubral-pallidoluysian atrophy. Abnormal expansion of triplet repeats for SCA7 and SCA8 was not detected. A total of 27.1% of the patients had still unknown SCA mutations. In addition, the GAA repeat in the frataxin gene was not abnormally expanded in 13 early-onset SCA patients with clinical features similar to those of Friedreich ataxia. Comparison of our results with those from other centers handling SCA showed that MJD is prevalent throughout Japan, but the frequencies of other dominant SCAs differ considerably even within Japan.
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Affiliation(s)
- H Sasaki
- Department of Neurology, Hokkaido University School of Medicine, N-15 W-7, Kita-ku, Sapporo, Japan.
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15
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Takiyama Y, Shimazaki H, Morita M, Soutome M, Sakoe K, Esumi E, Muramatsu S, Yoshida M, Igarashi S, Tanaka H, Tsuji S, Sasaki H, Wakisaka A, Nakano I, Nishizawa M. Maternal anticipation in Machado-Joseph disease (MJD): some maternal factors independent of the number of CAG repeat units may play a role in genetic anticipation in a Japanese MJD family. J Neurol Sci 1998; 155:141-5. [PMID: 9562258 DOI: 10.1016/s0022-510x(98)00012-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We studied the relationship between the number of CAG repeat units in the MJD1 gene and clinical features of Machado-Joseph disease (MJD) in eight patients from two generations of a Japanese MJD family. Because of lack of characteristic clinical signs of MJD such as dystonia, bulging eyes or facial myokymia, clinical diagnosis of MJD in this family was difficult to make prior to molecular testing for the CAG repeat expansion in the MJD1 gene. All the patients exhibited maternal transmission of MJD, and the intergenerational change in the number of CAG repeat units in the MJD1 gene was very small (+0.5+/-0.3, mean+/-S.E.M., n=4) in spite of marked genetic anticipation (-17.0 years/generation). In the present family, the degree of anticipation per repeat unit in maternal transmissions was much larger than that in maternal transmissions in the other six MJD families. This indicates that some maternal factors other than the increase of the number of CAG repeat units, which is known to be the basis of anticipation, may play a role in genetic anticipation in this MJD family.
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Affiliation(s)
- Y Takiyama
- Department of Neurology, Jichi Medical School, Tochigi, Japan.
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16
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Sasaki H, Fukazawa T, Wakisaka A, Hamada K, Hamada T, Koyama T, Tsuji S, Tashiro K. Central phenotype and related varieties of spinocerebellar ataxia 2 (SCA2): a clinical and genetic study with a pedigree in the Japanese. J Neurol Sci 1996; 144:176-81. [PMID: 8994121 DOI: 10.1016/s0022-510x(96)00225-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The gene for SCA2 has been mapped to chromosome 12q23-q24.1, but the mutant gene remained to be identified. When studying a Japanese family with SCA2, we noted that clinical features and disability varied among patients, with the central feature being progressive ataxia-slow eye movement-hyporeflexia syndrome. Additional symptoms were parkinsonism with minor cerebellar deficits, and severe ataxia with choreoathetosis. Our experience plus related literature documentation indicates that choreoathetosis is not so rare at the advanced stage of the disease, with onset at an early age, and that the variety of SCA2 phenotype depends on age at onset and duration of the disorder.
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Affiliation(s)
- H Sasaki
- Department of Neurology, Hokkaido University School of Medicine, Sapporo, Japan
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17
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Endo K, Sasaki H, Wakisaka A, Tanaka H, Saito M, Igarashi S, Takiyama Y, Sanpei K, Iwabuchi K, Suzuki Y, Onari K, Suzuki T, Weissenbach J, Weber JL, Nomura Y, Segawa M, Nishizawa M, Tsuji S. Strong linkage disequilibrium and haplotype analysis in Japanese pedigrees with Machado-Joseph disease. AMERICAN JOURNAL OF MEDICAL GENETICS 1996; 67:437-44. [PMID: 8886159 DOI: 10.1002/(sici)1096-8628(19960920)67:5<437::aid-ajmg1>3.0.co;2-h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To identify the markers tightly linked to Machado-Joseph disease (MJD) and to investigate whether a limited number of ancestral chromosomes are shared by Japanese MJD pedigrees, a detailed linkage analysis employing D14S55, D14S48, D14S67, D14S291, D14S280, AFM343vf1, D14S81, D14S265, D14S62, and D14S65 was performed. The results of multipoint linkage analysis as well as detection of critical recombination events indicate that the gene for MJD is localized in a 4-cM region between D14S280-D14S81. We found strong linkage disequilibria at AFM343vf1 and D14S81, and association of a few common haplotypes with MJD. These results indicate that there is an obvious founder effect in Japanese MJD and suggest the possibility of the existence of predisposing haplotypes which are prone to expansions of CAG repeats.
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Affiliation(s)
- K Endo
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Japan
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