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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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2
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Mouro Pinto R, Arning L, Giordano JV, Razghandi P, Andrew MA, Gillis T, Correia K, Mysore JS, Grote Urtubey DM, Parwez CR, von Hein SM, Clark HB, Nguyen HP, Förster E, Beller A, Jayadaev S, Keene CD, Bird TD, Lucente D, Vonsattel JP, Orr H, Saft C, Petrasch-Parwez E, Wheeler VC. Patterns of CAG repeat instability in the central nervous system and periphery in Huntington's disease and in spinocerebellar ataxia type 1. Hum Mol Genet 2021; 29:2551-2567. [PMID: 32761094 PMCID: PMC7471505 DOI: 10.1093/hmg/ddaa139] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/24/2020] [Accepted: 07/01/2020] [Indexed: 12/23/2022] Open
Abstract
The expanded HTT CAG repeat causing Huntington’s disease (HD) exhibits somatic expansion proposed to drive the rate of disease onset by eliciting a pathological process that ultimately claims vulnerable cells. To gain insight into somatic expansion in humans, we performed comprehensive quantitative analyses of CAG expansion in ~50 central nervous system (CNS) and peripheral postmortem tissues from seven adult-onset and one juvenile-onset HD individual. We also assessed ATXN1 CAG repeat expansion in brain regions of an individual with a neurologically and pathologically distinct repeat expansion disorder, spinocerebellar ataxia type 1 (SCA1). Our findings reveal similar profiles of tissue instability in all HD individuals, which, notably, were also apparent in the SCA1 individual. CAG expansion was observed in all tissues, but to different degrees, with multiple cortical regions and neostriatum tending to have the greatest instability in the CNS, and liver in the periphery. These patterns indicate different propensities for CAG expansion contributed by disease locus-independent trans-factors and demonstrate that expansion per se is not sufficient to cause cell type or disease-specific pathology. Rather, pathology may reflect distinct toxic processes triggered by different repeat lengths across cell types and diseases. We also find that the HTT CAG length-dependent expansion propensity of an individual is reflected in all tissues and in cerebrospinal fluid. Our data indicate that peripheral cells may be a useful source to measure CAG expansion in biomarker assays for therapeutic efforts, prompting efforts to dissect underlying mechanisms of expansion that may differ between the brain and periphery.
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Affiliation(s)
- 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
| | - Larissa Arning
- Department of Human Genetics, Ruhr-University Bochum, Bochum 44780, Germany
| | - James V Giordano
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Pedram Razghandi
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Marissa A Andrew
- 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
| | - Kevin Correia
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Jayalakshmi S Mysore
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | | | - Constanze R Parwez
- Department of Neuroanatomy and Molecular Brain Research, Institute of Anatomy, Ruhr-University Bochum, Bochum 44780, Germany
| | - Sarah M von Hein
- Department of Neurology, Huntington Centre NRW, St. Josef-Hospital, Ruhr-University Bochum, Bochum 44791, Germany
| | - H Brent Clark
- Department of Laboratory Medicine and Pathology, Institute of Translational Neuroscience, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Huu Phuc Nguyen
- Department of Human Genetics, Ruhr-University Bochum, Bochum 44780, Germany
| | - Eckart Förster
- Department of Neuroanatomy and Molecular Brain Research, Institute of Anatomy, Ruhr-University Bochum, Bochum 44780, Germany
| | - Allison Beller
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
| | - Suman Jayadaev
- Department of Neurology, University of Washington, Seattle, Washington 98195, USA
| | - C Dirk Keene
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
| | - Thomas D Bird
- Department of Neurology, University of Washington, Seattle, Washington 98195, USA.,Department of Medicine, University of Washington, Seattle, Washington 98195, USA.,Geriatrics Research Education and Clinical Center, VA Puget Sound Medical Center, Seattle, WA 98108, USA
| | - Diane Lucente
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Jean-Paul Vonsattel
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY 10032, USA
| | - Harry Orr
- Department of Laboratory Medicine and Pathology, Institute of Translational Neuroscience, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Carsten Saft
- Department of Neurology, Huntington Centre NRW, St. Josef-Hospital, Ruhr-University Bochum, Bochum 44791, Germany
| | - Elisabeth Petrasch-Parwez
- Department of Neuroanatomy and Molecular Brain Research, Institute of Anatomy, Ruhr-University Bochum, Bochum 44780, Germany
| | - 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
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3
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Kovalenko M, Erdin S, Andrew MA, St Claire J, Shaughnessey M, Hubert L, Neto JL, Stortchevoi A, Fass DM, Mouro Pinto R, Haggarty SJ, Wilson JH, Talkowski ME, Wheeler VC. Histone deacetylase knockouts modify transcription, CAG instability and nuclear pathology in Huntington disease mice. eLife 2020; 9:55911. [PMID: 32990597 PMCID: PMC7581428 DOI: 10.7554/elife.55911] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 09/28/2020] [Indexed: 12/13/2022] Open
Abstract
Somatic expansion of the Huntington’s disease (HD) CAG repeat drives the rate of a pathogenic process ultimately resulting in neuronal cell death. Although mechanisms of toxicity are poorly delineated, transcriptional dysregulation is a likely contributor. To identify modifiers that act at the level of CAG expansion and/or downstream pathogenic processes, we tested the impact of genetic knockout, in HttQ111 mice, of Hdac2 or Hdac3 in medium-spiny striatal neurons that exhibit extensive CAG expansion and exquisite disease vulnerability. Both knockouts moderately attenuated CAG expansion, with Hdac2 knockout decreasing nuclear huntingtin pathology. Hdac2 knockout resulted in a substantial transcriptional response that included modification of transcriptional dysregulation elicited by the HttQ111 allele, likely via mechanisms unrelated to instability suppression. Our results identify novel modifiers of different aspects of HD pathogenesis in medium-spiny neurons and highlight a complex relationship between the expanded Htt allele and Hdac2 with implications for targeting transcriptional dysregulation in HD.
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Affiliation(s)
- Marina Kovalenko
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | - Serkan Erdin
- Center for Genomic Medicine, Harvard Medical School, Boston, United States.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, United States
| | - Marissa A Andrew
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | - Jason St Claire
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | | | - Leroy Hubert
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, United States
| | - João Luís Neto
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | - Alexei Stortchevoi
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | - Daniel M Fass
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | - Ricardo Mouro Pinto
- Center for Genomic Medicine, Harvard Medical School, Boston, United States.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Stephen J Haggarty
- Center for Genomic Medicine, Harvard Medical School, Boston, United States.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - John H Wilson
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, United States
| | - Michael E Talkowski
- Center for Genomic Medicine, Harvard Medical School, Boston, United States.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, United States.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Vanessa C Wheeler
- Center for Genomic Medicine, Harvard Medical School, Boston, United States.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, United States
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4
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Flower M, Lomeikaite V, Holmans P, Jones L, Tabrizi SJ, Monckton DG. Reply: The repeat variant in MSH3 is not a genetic modifier for spinocerebellar ataxia type 3 and Friedreich's ataxia. Brain 2020; 143:e26. [PMID: 32154840 DOI: 10.1093/brain/awaa044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Michael Flower
- Department of Neurodegenerative Disease and Dementia Research Institute, UCL, UK
| | - Vilija Lomeikaite
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
| | - Peter Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, UK
| | - Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, UK
| | - Sarah J Tabrizi
- Department of Neurodegenerative Disease and Dementia Research Institute, UCL, UK
| | - Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
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5
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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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6
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Sproviero W, Shatunov A, Stahl D, Shoai M, van Rheenen W, Jones AR, Al-Sarraj S, Andersen PM, Bonini NM, Conforti FL, Van Damme P, Daoud H, Del Mar Amador M, Fogh I, Forzan M, Gaastra B, Gellera C, Gitler AD, Hardy J, Fratta P, La Bella V, Le Ber I, Van Langenhove T, Lattante S, Lee YC, Malaspina A, Meininger V, Millecamps S, Orrell R, Rademakers R, Robberecht W, Rouleau G, Ross OA, Salachas F, Sidle K, Smith BN, Soong BW, Sorarù G, Stevanin G, Kabashi E, Troakes C, van Broeckhoven C, Veldink JH, van den Berg LH, Shaw CE, Powell JF, Al-Chalabi A. ATXN2 trinucleotide repeat length correlates with risk of ALS. Neurobiol Aging 2017; 51:178.e1-178.e9. [PMID: 28017481 PMCID: PMC5302215 DOI: 10.1016/j.neurobiolaging.2016.11.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/14/2016] [Accepted: 11/16/2016] [Indexed: 12/13/2022]
Abstract
We investigated a CAG trinucleotide repeat expansion in the ATXN2 gene in amyotrophic lateral sclerosis (ALS). Two new case-control studies, a British dataset of 1474 ALS cases and 567 controls, and a Dutch dataset of 1328 ALS cases and 691 controls were analyzed. In addition, to increase power, we systematically searched PubMed for case-control studies published after 1 August 2010 that investigated the association between ATXN2 intermediate repeats and ALS. We conducted a meta-analysis of the new and existing studies for the relative risks of ATXN2 intermediate repeat alleles of between 24 and 34 CAG trinucleotide repeats and ALS. There was an overall increased risk of ALS for those carrying intermediate sized trinucleotide repeat alleles (odds ratio 3.06 [95% confidence interval 2.37-3.94]; p = 6 × 10-18), with an exponential relationship between repeat length and ALS risk for alleles of 29-32 repeats (R2 = 0.91, p = 0.0002). No relationship was seen for repeat length and age of onset or survival. In contrast to trinucleotide repeat diseases, intermediate ATXN2 trinucleotide repeat expansion in ALS does not predict age of onset but does predict disease risk.
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Affiliation(s)
- William Sproviero
- Department of Basic and Clinical Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Aleksey Shatunov
- Department of Basic and Clinical Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Daniel Stahl
- Department of Biostatistics, King's College London, Institute of Psychiatry, Psychology and Neuroscience, London, UK
| | - Maryam Shoai
- Department of Molecular Neuroscience, University College London (UCL) Institute of Neurology, London, UK
| | - Wouter van Rheenen
- Department of Neurology, Brain Center Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, Utrecht, the Netherlands
| | - Ashley R Jones
- Department of Basic and Clinical Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Safa Al-Sarraj
- Department of Clinical Neuropathology, King's College Hospital NHS Foundation Trust, London, UK
| | - Peter M Andersen
- Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå, Sweden
| | - Nancy M Bonini
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Philip Van Damme
- Neurology Department, University Hospitals Leuven, Leuven, Belgium; Vesalius Research Center, VIB, Leuven, Belgium; Disease (LIND), KU Leuven - University of Leuven, Leuven, Belgium
| | - Hussein Daoud
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Maria Del Mar Amador
- Department of Nervous System Diseases, ALS Paris ALS Center for Rare Diseases, Groupe Hospitalier Pitié Salpêtrière, APHP, Paris, France
| | - Isabella Fogh
- Department of Basic and Clinical Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Monica Forzan
- Clinical Genetics Unit, Department of Woman and Child Health, University of Padova, Padova, Italy
| | - Ben Gaastra
- Department of Basic and Clinical Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Cinzia Gellera
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Aaron D Gitler
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - John Hardy
- Department of Molecular Neuroscience, University College London (UCL) Institute of Neurology, London, UK
| | - Pietro Fratta
- Sobell Department of Motor Neuroscience and Movement Disorders, University College London (UCL) Institute of Neurology, London, UK
| | - Vincenzo La Bella
- ALS Clinical Research Center, Bio. Ne. C., University of Palermo, Palermo, Italy
| | - Isabelle Le Ber
- Institut du Cerveau et de la Moelle épinière (ICM), Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMRS1127, Paris, France; AP-HP, Hôpitaux Universitaires La Pitié Salpêtrière-Charles Foix, Centre de Référence des Démences Rares, Departement de Neurologie, Paris, France
| | - Tim Van Langenhove
- Neurodegenerative Brain Diseases Group, Department of Molecular Genetics, VIB, Antwerp, Belgium; Laboratory of Neurogenetics, Insititute Born-Bunge, University of Antwerp, Antwerp, Belgium; Department of Neurology, Antwerp University Hospital, Edegem, Belgium
| | - Serena Lattante
- Institut du Cerveau et de la Moelle épinière (ICM), Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMRS1127, Paris, France
| | - Yi-Chung Lee
- Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Neurology, National Yang-Ming University School of Medicine, Taipei, Taiwan; Brain Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Andrea Malaspina
- North-East London and Essex MND Care Centre - Neuroscience and Trauma Centre, Blizard, Institute of Cell and Molecular Medicine, Barts & the London School of Medicine & Dentistry, Barts Health NHS Trust, London, UK
| | - Vincent Meininger
- Hôpital de la Pitié-Salpêtrière, institut de recherche translationnelle en neurosciences (A-ICM), Paris, France; Hôpital de la Pitié-Salpêtrière, réseau SLA IdF, Paris, France
| | - Stéphanie Millecamps
- Institut du Cerveau et de la Moelle épinière (ICM), Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMRS1127, Paris, France
| | - Richard Orrell
- Department of Clinical Neuroscience, University College London (UCL) Institute of Neurology, London, UK
| | - Rosa Rademakers
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | - Wim Robberecht
- Vesalius Research Center, VIB, Leuven, Belgium; Disease (LIND), KU Leuven - University of Leuven, Leuven, Belgium
| | - Guy Rouleau
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Owen A Ross
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA
| | - Francois Salachas
- Department of Nervous System Diseases, ALS Paris ALS Center for Rare Diseases, Groupe Hospitalier Pitié Salpêtrière, APHP, Paris, France; Institut du Cerveau et de la Moelle épinière (ICM), Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMRS1127, Paris, France
| | - Katie Sidle
- Department of Molecular Neuroscience, University College London (UCL) Institute of Neurology, London, UK
| | - Bradley N Smith
- Department of Basic and Clinical Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Bing-Wen Soong
- Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan; Department of Neurology, National Yang-Ming University School of Medicine, Taipei, Taiwan; Brain Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Gianni Sorarù
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Giovanni Stevanin
- Institut du Cerveau et de la Moelle épinière (ICM), Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMRS1127, Paris, France; Neurogenetics team, Ecole Pratique des Hautes Etudes, Paris, France
| | - Edor Kabashi
- Institut du Cerveau et de la Moelle épinière (ICM), Inserm U1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMRS1127, Paris, France
| | - Claire Troakes
- Department of Basic and Clinical Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Christine van Broeckhoven
- Neurodegenerative Brain Diseases Group, Department of Molecular Genetics, VIB, Antwerp, Belgium; Laboratory of Neurogenetics, Insititute Born-Bunge, University of Antwerp, Antwerp, Belgium
| | - Jan H Veldink
- Department of Neurology, Brain Center Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, Utrecht, the Netherlands
| | - Leonard H van den Berg
- Department of Neurology, Brain Center Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, Utrecht, the Netherlands
| | - Christopher E Shaw
- Department of Basic and Clinical Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - John F Powell
- Department of Basic and Clinical Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Ammar Al-Chalabi
- Department of Basic and Clinical Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK.
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7
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Genetic Contributors to Intergenerational CAG Repeat Instability in Huntington's Disease Knock-In Mice. Genetics 2016; 205:503-516. [PMID: 27913616 PMCID: PMC5289832 DOI: 10.1534/genetics.116.195578] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/12/2016] [Indexed: 12/11/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion of a CAG trinucleotide repeat in exon 1 of the HTT gene. Longer repeat sizes are associated with increased disease penetrance and earlier ages of onset. Intergenerationally unstable transmissions are common in HD families, partly underlying the genetic anticipation seen in this disorder. HD CAG knock-in mouse models also exhibit a propensity for intergenerational repeat size changes. In this work, we examine intergenerational instability of the CAG repeat in over 20,000 transmissions in the largest HD knock-in mouse model breeding datasets reported to date. We confirmed previous observations that parental sex drives the relative ratio of expansions and contractions. The large datasets further allowed us to distinguish effects of paternal CAG repeat length on the magnitude and frequency of expansions and contractions, as well as the identification of large repeat size jumps in the knock-in models. Distinct degrees of intergenerational instability were observed between knock-in mice of six background strains, indicating the occurrence of trans-acting genetic modifiers. We also found that lines harboring a neomycin resistance cassette upstream of Htt showed reduced expansion frequency, indicative of a contributing role for sequences in cis, with the expanded repeat as modifiers of intergenerational instability. These results provide a basis for further understanding of the mechanisms underlying intergenerational repeat instability.
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8
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Age-, tissue- and length-dependent bidirectional somatic CAG•CTG repeat instability in an allelic series of R6/2 Huntington disease mice. Neurobiol Dis 2015; 76:98-111. [PMID: 25662336 DOI: 10.1016/j.nbd.2015.01.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 11/30/2014] [Accepted: 01/25/2015] [Indexed: 12/11/2022] Open
Abstract
The expansion of simple sequence CAG•CTG repeats is associated with a number of inherited disorders including Huntington disease (HD), myotonic dystrophy type 1 and several of the spinocerebellar ataxias. Inherited disease-associated alleles usually exceed 40 repeats and may be in excess of 1,000 repeats in some disorders. Inherited allele length is inversely proportional to age at onset, and frequent germline expansions account for the striking anticipation observed in affected families. Expanded disease associated alleles are also somatically unstable via a pathway that is age dependent and tissue specific, and also appears to be expansion biased. Somatic expansions are thought to contribute toward both tissue specificity and disease progression. Here we have examined the somatic mutational dynamics in brain and peripheral tissues from an allelic series of R6/2 HD transgenic mice inheriting from 52 to >700 CAG repeats. We found age-dependent, tissue-specific somatic instability, with particularly large expansions observed in the striatum and cortex. We also found a positive increase in somatic instability with increasing allele length. Surprisingly, however, the degree of somatic variation did not increase in a linear fashion, but leveled off with increasing allele length. Most unexpectedly, the almost exclusive bias toward the accumulation of expansions observed in mice inheriting smaller alleles was lost, and a high frequency of large somatic contractions was observed in mice inheriting very large alleles (>500 repeats). These data highlight the bidirectional nature of CAG•CTG repeat instability and the subtle balance that exists between expansion and contraction in vivo. Defining the dynamics and tissue specificity of expansion and contraction is important for understanding the role of genetic instability in pathophysiology and in particular the development of novel therapies based on suppressing expansions and/or promoting contractions.
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Usdin K, House NCM, Freudenreich CH. Repeat instability during DNA repair: Insights from model systems. Crit Rev Biochem Mol Biol 2015; 50:142-67. [PMID: 25608779 DOI: 10.3109/10409238.2014.999192] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The expansion of repeated sequences is the cause of over 30 inherited genetic diseases, including Huntington disease, myotonic dystrophy (types 1 and 2), fragile X syndrome, many spinocerebellar ataxias, and some cases of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Repeat expansions are dynamic, and disease inheritance and progression are influenced by the size and the rate of expansion. Thus, an understanding of the various cellular mechanisms that cooperate to control or promote repeat expansions is of interest to human health. In addition, the study of repeat expansion and contraction mechanisms has provided insight into how repair pathways operate in the context of structure-forming DNA, as well as insights into non-canonical roles for repair proteins. Here we review the mechanisms of repeat instability, with a special emphasis on the knowledge gained from the various model systems that have been developed to study this topic. We cover the repair pathways and proteins that operate to maintain genome stability, or in some cases cause instability, and the cross-talk and interactions between them.
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Affiliation(s)
- Karen Usdin
- Laboratory of Cell and Molecular Biology, NIDDK, NIH , Bethesda, MD , USA
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10
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Kumari A, Singh HR, Jha A, Swarnkar MK, Shankar R, Kumar S. Transcriptome sequencing of rhizome tissue of Sinopodophyllum hexandrum at two temperatures. BMC Genomics 2014; 15:871. [PMID: 25287271 PMCID: PMC4200142 DOI: 10.1186/1471-2164-15-871] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Accepted: 09/17/2014] [Indexed: 11/10/2022] Open
Abstract
Background Sinopodophyllum hexandrum is an endangered medicinal herb, which is commonly present in elevations ranging between 2,400–4,500 m and is sensitive to temperature. Medicinal property of the species is attributed to the presence of podophyllotoxin in the rhizome tissue. The present work analyzed transcriptome of rhizome tissue of S. hexandrum exposed to 15°C and 25°C to understand the temperature mediated molecular responses including those associated with podophyllotoxin biosynthesis. Results Deep sequencing of transcriptome with an average coverage of 88.34X yielded 60,089 assembled transcript sequences representing 20,387 unique genes having homology to known genes. Fragments per kilobase of exon per million fragments mapped (FPKM) based expression analysis revealed genes related to growth and development were over-expressed at 15°C, whereas genes involved in stress response were over-expressed at 25°C. There was a decreasing trend of podophyllotoxin accumulation at 25°C; data was well supported by the expression of corresponding genes of the pathway. FPKM data was validated by quantitative real-time polymerase chain reaction data using a total of thirty four genes and a positive correlation between the two platforms of gene expression was obtained. Also, detailed analyses yielded cytochrome P450s, methyltransferases and glycosyltransferases which could be the potential candidate hitherto unidentified genes of podophyllotoxin biosynthesis pathway. Conclusions The present work revealed temperature responsive transcriptome of S. hexandrum on Illumina platform. Data suggested expression of genes for growth and development and podophyllotoxin biosynthesis at 15°C, and prevalence of those associated with stress response at 25°C. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-871) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | - Ravi Shankar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, PO Box No, 6, Palampur 176 061, Himachal Pradesh, India.
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Saleh AA, Bhadra AK, Roy I. Cytotoxicity of mutant huntingtin fragment in yeast can be modulated by the expression level of wild type huntingtin fragment. ACS Chem Neurosci 2014; 5:205-15. [PMID: 24377263 PMCID: PMC3963126 DOI: 10.1021/cn400171d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 12/26/2013] [Indexed: 12/23/2022] Open
Abstract
Conflicting reports exist in the literature regarding the role of wild-type huntingtin in determining the toxicity of the aggregated, mutant huntingtin in Huntington's disease (HD). Some studies report the amelioration of toxicity of the mutant protein in the presence of the wild-type protein, while others indicate sequestration of the wild-type protein by mutant huntingtin. Over the years, yeast has been established as a valid model organism to study molecular changes associated with HD, especially at the protein level. We have used an inducible system to express human huntingtin fragments harboring normal (25Q) and pathogenic (103Q) polyglutamine lengths under the control of a galactose promoter in a yeast model of HD. We show that the relative expression level of each allele (wild-type/mutant) decides the cellular phenotype. When the expression level of wild-type huntingtin is high, an increase in the solubility of the mutant protein is observed. Fluorescence-recovery-after-photobleaching (FRAP) studies show that solubility reaches ∼94% in these cells. This leads to reduction in oxidative stress and cytotoxicity, and increases cell viability. In-cell FRET studies show that interaction between these proteins does not require the presence of a mediator. When the expression of wild-type huntingtin is low, it is sequestered into aggregates by the mutant protein. Even under these conditions, cytotoxicity is attenuated. Our findings indicate that the presence of wild-type huntingtin has a beneficial role even when its relative expression level is lower than that of the mutant protein.
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Affiliation(s)
- Aliabbas Ahmedbhai Saleh
- Department of Biotechnology, National Institute
of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India
| | - Ankan Kumar Bhadra
- Department of Biotechnology, National Institute
of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India
| | - Ipsita Roy
- Department of Biotechnology, National Institute
of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India
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12
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Deciphering the roles of trehalose and Hsp104 in the inhibition of aggregation of mutant huntingtin in a yeast model of Huntington's disease. Neuromolecular Med 2013; 16:280-91. [PMID: 24248470 DOI: 10.1007/s12017-013-8275-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 11/06/2013] [Indexed: 10/26/2022]
Abstract
Despite the significant amount of experimental data available on trehalose, the molecular mechanism responsible for its intracellular stabilising properties has not emerged yet. The repair of cellular homeostasis in many protein-misfolding diseases by trehalose is credited to the disaccharide being an inducer of autophagy, a mechanism by which aggregates of misfolded proteins are cleared by the cell. In this work, we expressed the pathogenic N-terminal fragment of huntingtin in Δnth1 mutant (unable to degrade trehalose) of Saccharomyces cerevisiae BY4742 strain. We show that the presence of trehalose resulted in the partitioning of the mutant huntingtin in the soluble fraction of the cell. This led to reduced oxidative stress and improved cell survival. The beneficial effect was independent of the expression of the major cellular antioxidant enzyme, superoxide dismutase. Additionally, trehalose led to the overexpression of the heat shock protein, Hsp104p, in mutant huntingtin-expressing cells, and resulted in rescue of the endocytotic defect in the yeast cell. We propose that at least in the initial stages of aggregation, trehalose functions as a stabiliser, increasing the level of monomeric mutant huntingtin protein, with its concomitant beneficial effects, in addition to its role as an inducer of autophagy.
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Higham CF, Monckton DG. Modelling and inference reveal nonlinear length-dependent suppression of somatic instability for small disease associated alleles in myotonic dystrophy type 1 and Huntington disease. J R Soc Interface 2013; 10:20130605. [PMID: 24047873 DOI: 10.1098/rsif.2013.0605] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
More than 20 human genetic diseases are associated with inheriting an unstable expanded DNA simple sequence tandem repeat, for example, CTG (cytosine-thymine-guanine) repeats in myotonic dystrophy type 1 (DM1) and CAG (cytosine-adenine-guanine) repeats in Huntington disease (HD). These sequences mutate by changing the number of repeats not just between generations, but also during the lifetime of affected individuals. Levels of somatic instability contribute to disease onset and progression but as changes are tissue-specific, age- and repeat length-dependent, interpretation of the level of somatic instability in an individual is confounded by these considerations. Mathematical models, fitted to CTG repeat length distributions derived from blood DNA, from a large cohort of DM1-affected or at risk individuals, have recently been used to quantify inherited repeat lengths and mutation rates. Taking into account age, the estimated mutation rates are lower than predicted among individuals with small alleles (inherited repeat lengths less than 100 CTGs), suggesting that these rates may be suppressed at the lower end of the disease-causing range. In this study, we propose that a length-specific effect operates within this range and tested this hypothesis using a model comparison approach. To calibrate the extended model, we used data derived from blood DNA from DM1 individuals and, for the first time, buccal DNA from HD individuals. In a novel application of this extended model, we identified individuals whose effective repeat length, with regards to somatic instability, is less than their actual repeat length. A plausible explanation for this distinction is that the expanded repeat tract is compromised by interruptions or other unusual features. We quantified effective length for a large cohort of DM1 individuals and showed that effective length better predicts age of onset than inherited repeat length, thus improving the genotype-phenotype correlation. Under the extended model, we removed some of the bias in mutation rates making them less length-dependent. Consequently, rates adjusted in this way will be better suited as quantitative traits to investigate cis- or trans-acting modifiers of somatic mosaicism, disease onset and progression.
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Affiliation(s)
- Catherine F Higham
- School of Mathematics and Statistics, College of Science and Engineering, University of Glasgow, Glasgow G12 8QQ, UK.
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Fiszer A, Krzyzosiak WJ. RNA toxicity in polyglutamine disorders: concepts, models, and progress of research. J Mol Med (Berl) 2013; 91:683-91. [PMID: 23512265 PMCID: PMC3659269 DOI: 10.1007/s00109-013-1016-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 02/19/2013] [Accepted: 02/25/2013] [Indexed: 01/13/2023]
Abstract
In Huntington's disease and other polyglutamine (polyQ) disorders, mutant proteins containing a long polyQ stretch are well documented as the trigger of numerous aberrant cellular processes that primarily lead to degeneration and, ultimately, the death of neuronal cells. However, mutant transcripts containing expanded CAG repeats may also be toxic and contribute to cellular dysfunction. The exact nature and importance of RNA toxicity in polyQ diseases are only beginning to be recognized, and the first insights have mainly resulted from studies using simple model systems. In this review, we briefly present the basic mechanisms of protein toxicity in polyQ disorders and RNA toxicity in myotonic dystrophy type 1 and discuss recent results suggesting that the pathogenesis of polyQ diseases may also be mediated by mutant transcripts. This review is focused on the experimental systems used thus far to demonstrate RNA toxicity in polyQ disorders and the design of new systems that will be more relevant to the human disease situation and capable of separating RNA toxicity from protein toxicity.
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Affiliation(s)
- Agnieszka Fiszer
- Laboratory of Molecular Biomedicine, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
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15
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Tomé S, Manley K, Simard JP, Clark GW, Slean MM, Swami M, Shelbourne PF, Tillier ERM, Monckton DG, Messer A, Pearson CE. MSH3 polymorphisms and protein levels affect CAG repeat instability in Huntington's disease mice. PLoS Genet 2013; 9:e1003280. [PMID: 23468640 PMCID: PMC3585117 DOI: 10.1371/journal.pgen.1003280] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 12/12/2012] [Indexed: 01/21/2023] Open
Abstract
Expansions of trinucleotide CAG/CTG repeats in somatic tissues are thought to contribute to ongoing disease progression through an affected individual's life with Huntington's disease or myotonic dystrophy. Broad ranges of repeat instability arise between individuals with expanded repeats, suggesting the existence of modifiers of repeat instability. Mice with expanded CAG/CTG repeats show variable levels of instability depending upon mouse strain. However, to date the genetic modifiers underlying these differences have not been identified. We show that in liver and striatum the R6/1 Huntington's disease (HD) (CAG)∼100 transgene, when present in a congenic C57BL/6J (B6) background, incurred expansion-biased repeat mutations, whereas the repeat was stable in a congenic BALB/cByJ (CBy) background. Reciprocal congenic mice revealed the Msh3 gene as the determinant for the differences in repeat instability. Expansion bias was observed in congenic mice homozygous for the B6 Msh3 gene on a CBy background, while the CAG tract was stabilized in congenics homozygous for the CBy Msh3 gene on a B6 background. The CAG stabilization was as dramatic as genetic deficiency of Msh2. The B6 and CBy Msh3 genes had identical promoters but differed in coding regions and showed strikingly different protein levels. B6 MSH3 variant protein is highly expressed and associated with CAG expansions, while the CBy MSH3 variant protein is expressed at barely detectable levels, associating with CAG stability. The DHFR protein, which is divergently transcribed from a promoter shared by the Msh3 gene, did not show varied levels between mouse strains. Thus, naturally occurring MSH3 protein polymorphisms are modifiers of CAG repeat instability, likely through variable MSH3 protein stability. Since evidence supports that somatic CAG instability is a modifier and predictor of disease, our data are consistent with the hypothesis that variable levels of CAG instability associated with polymorphisms of DNA repair genes may have prognostic implications for various repeat-associated diseases. The genetic instability of repetitive DNA sequences in particular genes can lead to numerous neurodegenerative, neurological, and neuromuscular diseases. These diseases show progressively increasing severity of symptoms through the life of the affected individual, a phenomenon that is linked with increasing instability of the repeated sequences as the person ages. There is variability in the levels of this instability between individuals—the source of this variability is unknown. We have shown in a mouse model of repeat instability that small differences in a certain DNA repair gene, MSH3, whose protein is known to fix broken DNA, can lead to variable levels of repeat instability. These DNA repair variants lead to different repair protein levels, where lower levels lead to reduced repeat instability. Our findings reveal that such naturally occurring variations in DNA repair genes in affected humans may serve as a predictor of disease progression. Moreover, our findings support the concept that pharmacological reduction of MSH3 protein should reduce repeat instability and disease progression.
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Affiliation(s)
- Stéphanie Tomé
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Kevin Manley
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, University at Albany, SUNY, Albany, New York, United States of America
| | - Jodie P. Simard
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Greg W. Clark
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Campbell Family Institute for Cancer Research, Ontario Cancer Institute, University Health Network, Toronto, Ontario, Canada
| | - Meghan M. Slean
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Meera Swami
- Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Peggy F. Shelbourne
- Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Elisabeth R. M. Tillier
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Campbell Family Institute for Cancer Research, Ontario Cancer Institute, University Health Network, Toronto, Ontario, Canada
| | - Darren G. Monckton
- Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Anne Messer
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, University at Albany, SUNY, Albany, New York, United States of America
| | - Christopher E. Pearson
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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16
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van der Zee J, Gijselinck I, Dillen L, Van Langenhove T, Theuns J, Engelborghs S, Philtjens S, Vandenbulcke M, Sleegers K, Sieben A, Bäumer V, Maes G, Corsmit E, Borroni B, Padovani A, Archetti S, Perneczky R, Diehl-Schmid J, de Mendonça A, Miltenberger-Miltenyi G, Pereira S, Pimentel J, Nacmias B, Bagnoli S, Sorbi S, Graff C, Chiang HH, Westerlund M, Sanchez-Valle R, Llado A, Gelpi E, Santana I, Almeida MR, Santiago B, Frisoni G, Zanetti O, Bonvicini C, Synofzik M, Maetzler W, Vom Hagen JM, Schöls L, Heneka MT, Jessen F, Matej R, Parobkova E, Kovacs GG, Ströbel T, Sarafov S, Tournev I, Jordanova A, Danek A, Arzberger T, Fabrizi GM, Testi S, Salmon E, Santens P, Martin JJ, Cras P, Vandenberghe R, De Deyn PP, Cruts M, Van Broeckhoven C, van der Zee J, Gijselinck I, Dillen L, Van Langenhove T, Theuns J, Philtjens S, Sleegers K, Bäumer V, Maes G, Corsmit E, Cruts M, Van Broeckhoven C, van der Zee J, Gijselinck I, Dillen L, Van Langenhove T, Philtjens S, Theuns J, Sleegers K, Bäumer V, Maes G, Cruts M, Van Broeckhoven C, Engelborghs S, De Deyn PP, Cras P, Engelborghs S, De Deyn PP, Vandenbulcke M, Vandenbulcke M, Borroni B, Padovani A, Archetti S, Perneczky R, Diehl-Schmid J, Synofzik M, Maetzler W, Müller Vom Hagen J, Schöls L, Synofzik M, Maetzler W, Müller Vom Hagen J, Schöls L, Heneka MT, Jessen F, Ramirez A, Kurzwelly D, Sachtleben C, Mairer W, de Mendonça A, Miltenberger-Miltenyi G, Pereira S, Firmo C, Pimentel J, Sanchez-Valle R, Llado A, Antonell A, Molinuevo J, Gelpi E, Graff C, Chiang HH, Westerlund M, Graff C, Kinhult Ståhlbom A, Thonberg H, Nennesmo I, Börjesson-Hanson A, Nacmias B, Bagnoli S, Sorbi S, Bessi V, Piaceri I, Santana I, Santiago B, Santana I, Helena Ribeiro M, Rosário Almeida M, Oliveira C, Massano J, Garret C, Pires P, Frisoni G, Zanetti O, Bonvicini C, Sarafov S, Tournev I, Jordanova A, Tournev I, Kovacs GG, Ströbel T, Heneka MT, Jessen F, Ramirez A, Kurzwelly D, Sachtleben C, Mairer W, Jessen F, Matej R, Parobkova E, Danel A, Arzberger T, Maria Fabrizi G, Testi S, Ferrari S, Cavallaro T, Salmon E, Santens P, Cras P. A pan-European study of the C9orf72 repeat associated with FTLD: geographic prevalence, genomic instability, and intermediate repeats. Hum Mutat 2013; 34:363-73. [PMID: 23111906 PMCID: PMC3638346 DOI: 10.1002/humu.22244] [Citation(s) in RCA: 206] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 10/09/2012] [Indexed: 12/12/2022]
Abstract
We assessed the geographical distribution of C9orf72 G(4) C(2) expansions in a pan-European frontotemporal lobar degeneration (FTLD) cohort (n = 1,205), ascertained by the European Early-Onset Dementia (EOD) consortium. Next, we performed a meta-analysis of our data and that of other European studies, together 2,668 patients from 15 Western European countries. The frequency of the C9orf72 expansions in Western Europe was 9.98% in overall FTLD, with 18.52% in familial, and 6.26% in sporadic FTLD patients. Outliers were Finland and Sweden with overall frequencies of respectively 29.33% and 20.73%, but also Spain with 25.49%. In contrast, prevalence in Germany was limited to 4.82%. In addition, we studied the role of intermediate repeats (7-24 repeat units), which are strongly correlated with the risk haplotype, on disease and C9orf72 expression. In vitro reporter gene expression studies demonstrated significantly decreased transcriptional activity of C9orf72 with increasing number of normal repeat units, indicating that intermediate repeats might act as predisposing alleles and in favor of the loss-of-function disease mechanism. Further, we observed a significantly increased frequency of short indels in the GC-rich low complexity sequence adjacent to the G(4) C(2) repeat in C9orf72 expansion carriers (P < 0.001) with the most common indel creating one long contiguous imperfect G(4) C(2) repeat, which is likely more prone to replication slippage and pathological expansion.
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