1
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Stoebner ZA, Hett K, Lyu I, Johnson H, Paulsen JS, Long JD, Oguz I. Comprehensive shape analysis of the cortex in Huntington's disease. Hum Brain Mapp 2023; 44:1417-1431. [PMID: 36409662 PMCID: PMC9921229 DOI: 10.1002/hbm.26125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 09/15/2022] [Accepted: 09/28/2022] [Indexed: 11/22/2022] Open
Abstract
The striatum has traditionally been the focus of Huntington's disease research due to the primary insult to this region and its central role in motor symptoms. Beyond the striatum, evidence of cortical alterations caused by Huntington's disease has surfaced. However, findings are not coherent between studies which have used cortical thickness for Huntington's disease since it is the well-established cortical metric of interest in other diseases. In this study, we propose a more comprehensive approach to cortical morphology in Huntington's disease using cortical thickness, sulcal depth, and local gyrification index. Our results show consistency with prior findings in cortical thickness, including its limitations. Our comparison between cortical thickness and local gyrification index underscores the complementary nature of these two measures-cortical thickness detects changes in the sensorimotor and posterior areas while local gyrification index identifies insular differences. Since local gyrification index and cortical thickness measures detect changes in different regions, the two used in tandem could provide a clinically relevant measure of disease progression. Our findings suggest that differences in insular regions may correspond to earlier neurodegeneration and may provide a complementary cortical measure for detection of subtle early cortical changes due to Huntington's disease.
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Affiliation(s)
- Zachary A Stoebner
- Department of Computer Science, Vanderbilt University, Nashville, Tennessee, USA.,University of Texas at Austin, Austin, Texas, USA
| | - Kilian Hett
- Department of Computer Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Ilwoo Lyu
- Department of Computer Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Computer Science and Engineering, UNIST, Ulsan, South Korea
| | - Hans Johnson
- Department of Electrical and Computer Engineering, University of Iowa, Iowa City, Iowa, USA
| | - Jane S Paulsen
- Department of Neurology, University of Wisconsin, Madison, Wisconsin, USA
| | - Jeffrey D Long
- Department of Psychiatry, University of Iowa, Iowa City, Iowa, USA.,Department of Biostatistics, University of Iowa, Iowa City, Iowa, USA
| | - Ipek Oguz
- Department of Computer Science, Vanderbilt University, Nashville, Tennessee, USA
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2
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Papoutsi M, Flower M, Hensman Moss DJ, Holmans P, Estevez-Fraga C, Johnson EB, Scahill RI, Rees G, Langbehn D, Tabrizi SJ. Intellectual enrichment and genetic modifiers of cognition and brain volume in Huntington's disease. Brain Commun 2022; 4:fcac279. [PMID: 36519153 PMCID: PMC9732861 DOI: 10.1093/braincomms/fcac279] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 08/22/2022] [Accepted: 10/27/2022] [Indexed: 12/14/2022] Open
Abstract
An important step towards the development of treatments for cognitive impairment in ageing and neurodegenerative diseases is to identify genetic and environmental modifiers of cognitive function and understand the mechanism by which they exert an effect. In Huntington's disease, the most common autosomal dominant dementia, a small number of studies have identified intellectual enrichment, i.e. a cognitively stimulating lifestyle and genetic polymorphisms as potential modifiers of cognitive function. The aim of our study was to further investigate the relationship and interaction between genetic factors and intellectual enrichment on cognitive function and brain atrophy in Huntington's disease. For this purpose, we analysed data from Track-HD, a multi-centre longitudinal study in Huntington's disease gene carriers and focused on the role of intellectual enrichment (estimated at baseline) and the genes FAN1, MSH3, BDNF, COMT and MAPT in predicting cognitive decline and brain atrophy. We found that carrying the 3a allele in the MSH3 gene had a positive effect on global cognitive function and brain atrophy in multiple cortical regions, such that 3a allele carriers had a slower rate of cognitive decline and atrophy compared with non-carriers, in agreement with its role in somatic instability. No other genetic predictor had a significant effect on cognitive function and the effect of MSH3 was independent of intellectual enrichment. Intellectual enrichment also had a positive effect on cognitive function; participants with higher intellectual enrichment, i.e. those who were better educated, had higher verbal intelligence and performed an occupation that was intellectually engaging, had better cognitive function overall, in agreement with previous studies in Huntington's disease and other dementias. We also found that intellectual enrichment interacted with the BDNF gene, such that the positive effect of intellectual enrichment was greater in Met66 allele carriers than non-carriers. A similar relationship was also identified for changes in whole brain and caudate volume; the positive effect of intellectual enrichment was greater for Met66 allele carriers, rather than for non-carriers. In summary, our study provides additional evidence for the beneficial role of intellectual enrichment and carrying the 3a allele in MSH3 in cognitive function in Huntington's disease and their effect on brain structure.
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Affiliation(s)
- Marina Papoutsi
- UCL Huntington’s Disease Centre, Queen Square Institute of Neurology, University College London, London, UK
- Ixico plc, London, UK
| | - Michael Flower
- UCL Huntington’s Disease Centre, Queen Square Institute of Neurology, University College London, London, UK
| | - Davina J Hensman Moss
- UCL Huntington’s Disease Centre, Queen Square Institute of Neurology, University College London, London, UK
| | - Peter Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Cardiff, UK
| | - Carlos Estevez-Fraga
- UCL Huntington’s Disease Centre, Queen Square Institute of Neurology, University College London, London, UK
| | - Eileanoir B Johnson
- UCL Huntington’s Disease Centre, Queen Square Institute of Neurology, University College London, London, UK
| | - Rachael I Scahill
- UCL Huntington’s Disease Centre, Queen Square Institute of Neurology, University College London, London, UK
| | - Geraint Rees
- Wellcome Centre for Human Neuroimaging, Queen Square Institute of Neurology, University College London, London, UK
- Institute of Cognitive Neuroscience, University College London, London, UK
| | - Douglas Langbehn
- Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Sarah J Tabrizi
- UCL Huntington’s Disease Centre, Queen Square Institute of Neurology, University College London, London, UK
- UK Dementia Research Institute at University College London, London, UK
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3
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CAG repeat-binding small molecule improves motor coordination impairment in a mouse model of Dentatorubral-pallidoluysian atrophy. Neurobiol Dis 2021; 163:105604. [PMID: 34968706 DOI: 10.1016/j.nbd.2021.105604] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 12/06/2021] [Accepted: 12/26/2021] [Indexed: 11/22/2022] Open
Abstract
Dentatorubral-pallidoluysian atrophy (DRPLA) is a devastating genetic disease presenting myoclonus, epilepsy, ataxia, and dementia. DRPLA is caused by the expansion of a CAG repeat in the ATN1 gene. Aggregation of the polyglutamine-expanded ATN1 protein causes neuro-degeneration of the dentatorubral and pallidoluysian systems. The expanded CAG repeats are unstable, and ongoing repeat expansions contribute to disease onset, progression, and severity. Inducing contractions of expanded repeats can be a means to treat DRPLA, for which no disease-modifying or curative therapies exist at present. Previously, we characterized a small molecule, naphthyridine-azaquinolone (NA), which binds to CAG slip-out structures and induces repeat contraction in Huntington's disease mice. Here, we demonstrate that long-term intracerebroventricular infusion of NA leads to repeat contraction, reductions in mutant ATN1 aggregation, and improved motor phenotype in a murine model of DRPLA. Furthermore, NA-induced contraction resulted in the modification of repeat-length-dependent dysregulation of gene expression profiles in DRPLA mice. Our study reveals the therapeutic potential of repeat contracting small molecules for repeat expansion disorders, such as DRPLA.
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4
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Gusella JF, Lee JM, MacDonald ME. Huntington's disease: nearly four decades of human molecular genetics. Hum Mol Genet 2021; 30:R254-R263. [PMID: 34169318 PMCID: PMC8490011 DOI: 10.1093/hmg/ddab170] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 11/13/2022] Open
Abstract
Huntington's disease (HD) is a devastating neurogenetic disorder whose familial nature and progressive course were first described in the 19th century but for which no disease-modifying treatment is yet available. Through the active participation of HD families, this disorder has acted as a flagship for the application of human molecular genetic strategies to identify disease genes, understand pathogenesis and identify rational targets for development of therapies.
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Affiliation(s)
- James F Gusella
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Jong-Min Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Marcy E MacDonald
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA 02142, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
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5
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Wright GEB, Caron NS, Ng B, Casal L, Casazza W, Xu X, Ooi J, Pouladi MA, Mostafavi S, Ross CJD, Hayden MR. Gene expression profiles complement the analysis of genomic modifiers of the clinical onset of Huntington disease. Hum Mol Genet 2021; 29:2788-2802. [PMID: 32898862 PMCID: PMC7530525 DOI: 10.1093/hmg/ddaa184] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/25/2020] [Accepted: 08/10/2020] [Indexed: 12/13/2022] Open
Abstract
Huntington disease (HD) is a neurodegenerative disorder that is caused by a CAG repeat expansion in HTT. The length of this repeat, however, only explains a proportion of the variability in age of onset in patients. Genome-wide association studies have identified modifiers that contribute toward a proportion of the observed variance. By incorporating tissue-specific transcriptomic information with these results, additional modifiers can be identified. We performed a transcriptome-wide association study assessing heritable differences in genetically determined expression in diverse tissues, with genome-wide data from over 4000 patients. Functional validation of prioritized genes was undertaken in isogenic HD stem cells and patient brains. Enrichment analyses were performed with biologically relevant gene sets to identify the core pathways. HD-associated gene coexpression modules were assessed for associations with neurological phenotypes in an independent cohort and to guide drug repurposing analyses. Transcriptomic analyses identified genes that were associated with age of HD onset and displayed colocalization with gene expression signals in brain tissue (FAN1, GPR161, PMS2, SUMF2), with supporting evidence from functional experiments. This included genes involved in DNA repair, as well as novel-candidate modifier genes that have been associated with other neurological conditions. Further, cortical coexpression modules were also associated with cognitive decline and HD-related traits in a longitudinal cohort. In summary, the combination of population-scale gene expression information with HD patient genomic data identified novel modifier genes for the disorder. Further, these analyses expanded the pathways potentially involved in modifying HD onset and prioritized candidate therapeutics for future study.
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Affiliation(s)
- Galen E B Wright
- Centre for Molecular Medicine and Therapeutics, Vancouver, British Columbia V5Z 4H4, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6H 3N1, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada
| | - Nicholas S Caron
- Centre for Molecular Medicine and Therapeutics, Vancouver, British Columbia V5Z 4H4, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6H 3N1, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada
| | - Bernard Ng
- Centre for Molecular Medicine and Therapeutics, Vancouver, British Columbia V5Z 4H4, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6H 3N1, Canada.,Department of Statistics, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Lorenzo Casal
- Centre for Molecular Medicine and Therapeutics, Vancouver, British Columbia V5Z 4H4, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6H 3N1, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada
| | - William Casazza
- Centre for Molecular Medicine and Therapeutics, Vancouver, British Columbia V5Z 4H4, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6H 3N1, Canada.,Department of Statistics, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Xiaohong Xu
- Translational Laboratory in Genetic Medicine (TLGM), Agency for Science, Technology and Research (A*STAR), Singapore 138648, Singapore
| | - Jolene Ooi
- Translational Laboratory in Genetic Medicine (TLGM), Agency for Science, Technology and Research (A*STAR), Singapore 138648, Singapore
| | - Mahmoud A Pouladi
- Translational Laboratory in Genetic Medicine (TLGM), Agency for Science, Technology and Research (A*STAR), Singapore 138648, Singapore.,Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Sara Mostafavi
- Centre for Molecular Medicine and Therapeutics, Vancouver, British Columbia V5Z 4H4, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6H 3N1, Canada.,Department of Statistics, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Colin J D Ross
- BC Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada.,Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.,Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, Vancouver, British Columbia V5Z 4H4, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6H 3N1, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada
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6
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Barazesh M, Mohammadi S, Bahrami Y, Mokarram P, Morowvat MH, Saidijam M, Karimipoor M, Kavousipour S, Vosoughi AR, Khanaki K. CRISPR/Cas9 Technology as a Modern Genetic Manipulation Tool for Recapitulating of Neurodegenerative Disorders in Large Animal Models. Curr Gene Ther 2021; 21:130-148. [PMID: 33319680 DOI: 10.2174/1566523220666201214115024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/12/2020] [Accepted: 11/23/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Neurodegenerative diseases are often the consequence of alterations in structures and functions of the Central Nervous System (CNS) in patients. Despite obtaining massive genomic information concerning the molecular basis of these diseases and since the neurological disorders are multifactorial, causal connections between pathological pathways at the molecular level and CNS disorders development have remained obscure and need to be elucidated to a great extent. OBJECTIVE Animal models serve as accessible and valuable tools for understanding and discovering the roles of causative factors in the development of neurodegenerative disorders and finding appropriate treatments. Contrary to rodents and other small animals, large animals, especially non-human primates (NHPs), are remarkably similar to humans; hence, they establish suitable models for recapitulating the main human's neuropathological manifestations that may not be seen in rodent models. In addition, they serve as useful models to discover effective therapeutic targets for neurodegenerative disorders due to their similarity to humans in terms of physiology, evolutionary distance, anatomy, and behavior. METHODS In this review, we recommend different strategies based on the CRISPR-Cas9 system for generating animal models of human neurodegenerative disorders and explaining in vivo CRISPR-Cas9 delivery procedures that are applied to disease models for therapeutic purposes. RESULTS With the emergence of CRISPR/Cas9 as a modern specific gene-editing technology in the field of genetic engineering, genetic modification procedures such as gene knock-in and knock-out have become increasingly easier compared to traditional gene targeting techniques. Unlike the old techniques, this versatile technology can efficiently generate transgenic large animal models without the need to complicate lab instruments. Hence, these animals can accurately replicate the signs of neurodegenerative disorders. CONCLUSION Preclinical applications of CRISPR/Cas9 gene-editing technology supply a unique opportunity to establish animal models of neurodegenerative disorders with high accuracy and facilitate perspectives for breakthroughs in the research on the nervous system disease therapy and drug discovery. Furthermore, the useful outcomes of CRISPR applications in various clinical phases are hopeful for their translation to the clinic in a short time.
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Affiliation(s)
- Mahdi Barazesh
- School of Paramedical, Gerash University of Medical Sciences, Gerash, Iran
| | - Shiva Mohammadi
- Department of Medical Biotechnology, School of Medicine, Lorestan University of Medical Sciences, Khoram Abad, Iran
| | - Yadollah Bahrami
- Molecular Biology Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Pooneh Mokarram
- Autophagy Research center, Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | | | - Massoud Saidijam
- Department of Molecular Medicine and Genetics, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Morteza Karimipoor
- Molecular Medicine Department, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Soudabeh Kavousipour
- Molecular Medicine Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Amir Reza Vosoughi
- Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, Max Rady College of Medicine, University of Manitoba, Winnipeg, Canada
| | - Korosh Khanaki
- Medical Biotechnology Research Center, Paramedicine Faculty, Guilan University of Medical Sciences, Rasht, Iran
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7
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Jung R, Lee Y, Barker D, Correia K, Shin B, Loupe J, Collins RL, Lucente D, Ruliera J, Gillis T, Mysore JS, Rodan L, Picker J, Lee JM, Howland D, Lee R, Kwak S, MacDonald ME, Gusella JF, Seong IS. Mutations causing Lopes-Maciel-Rodan syndrome are huntingtin hypomorphs. Hum Mol Genet 2021; 30:135-148. [PMID: 33432339 DOI: 10.1093/hmg/ddaa283] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 11/18/2020] [Accepted: 12/24/2020] [Indexed: 12/31/2022] Open
Abstract
Huntington's disease pathogenesis involves a genetic gain-of-function toxicity mechanism triggered by the expanded HTT CAG repeat. Current therapeutic efforts aim to suppress expression of total or mutant huntingtin, though the relationship of huntingtin's normal activities to the gain-of-function mechanism and what the effects of huntingtin-lowering might be are unclear. Here, we have re-investigated a rare family segregating two presumed HTT loss-of-function (LoF) variants associated with the developmental disorder, Lopes-Maciel-Rodan syndrome (LOMARS), using whole-genome sequencing of DNA from cell lines, in conjunction with analysis of mRNA and protein expression. Our findings correct the muddled annotation of these HTT variants, reaffirm they are the genetic cause of the LOMARS phenotype and demonstrate that each variant is a huntingtin hypomorphic mutation. The NM_002111.8: c.4469+1G>A splice donor variant results in aberrant (exon 34) splicing and severely reduced mRNA, whereas, surprisingly, the NM_002111.8: c.8157T>A NP_002102.4: Phe2719Leu missense variant results in abnormally rapid turnover of the Leu2719 huntingtin protein. Thus, although rare and subject to an as yet unknown LoF intolerance at the population level, bona fide HTT LoF variants can be transmitted by normal individuals leading to severe consequences in compound heterozygotes due to huntingtin deficiency.
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Affiliation(s)
- Roy Jung
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Yejin Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Douglas Barker
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Kevin Correia
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Baehyun Shin
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Jacob Loupe
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Ryan L Collins
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA.,Program in Bioinformatics and Integrative Genomics, Division of Medical Sciences, Harvard Medical School, Boston, MA 02114, USA
| | - Diane Lucente
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Jayla Ruliera
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Tammy Gillis
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Jayalakshmi S Mysore
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - Lance Rodan
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Neurology, Boston Children's Hospital, Harvard Medical School, MA 02115, USA
| | - Jonathan Picker
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Child and Adolescent Psychiatry, Boston Children's Hospital, Harvard Medical School, MA 02115, USA
| | - Jong-Min Lee
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
| | - David Howland
- CHDI Management/CHDI Foundation Inc., Princeton, NJ 08540, USA
| | - Ramee Lee
- CHDI Management/CHDI Foundation Inc., Princeton, NJ 08540, USA
| | - Seung Kwak
- CHDI Management/CHDI Foundation Inc., Princeton, NJ 08540, USA
| | - Marcy E MacDonald
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA.,Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA
| | - James F Gusella
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Medical and Population Genetics Program, The Broad Institute of M.I.T. and Harvard, Cambridge, MA, 02142, USA.,Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA
| | - Ihn Sik Seong
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02114, USA
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8
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Nakamori M, Mochizuki H. Targeting Expanded Repeats by Small Molecules in Repeat Expansion Disorders. Mov Disord 2020; 36:298-305. [DOI: 10.1002/mds.28397] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/20/2020] [Accepted: 10/26/2020] [Indexed: 12/14/2022] Open
Affiliation(s)
- Masayuki Nakamori
- Department of Neurology Osaka University Graduate School of Medicine Osaka Japan
| | - Hideki Mochizuki
- Department of Neurology Osaka University Graduate School of Medicine Osaka Japan
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9
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New developments in Huntington's disease and other triplet repeat diseases: DNA repair turns to the dark side. Neuronal Signal 2020; 4:NS20200010. [PMID: 33224521 PMCID: PMC7672267 DOI: 10.1042/ns20200010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 02/08/2023] Open
Abstract
Huntington’s disease (HD) is a fatal, inherited neurodegenerative disease that causes neuronal death, particularly in medium spiny neurons. HD leads to serious and progressive motor, cognitive and psychiatric symptoms. Its genetic basis is an expansion of the CAG triplet repeat in the HTT gene, leading to extra glutamines in the huntingtin protein. HD is one of nine genetic diseases in this polyglutamine (polyQ) category, that also includes a number of inherited spinocerebellar ataxias (SCAs). Traditionally it has been assumed that HD age of onset and disease progression were solely the outcome of age-dependent exposure of neurons to toxic effects of the inherited mutant huntingtin protein. However, recent genome-wide association studies (GWAS) have revealed significant effects of genetic variants outside of HTT. Surprisingly, these variants turn out to be mostly in genes encoding DNA repair factors, suggesting that at least some disease modulation occurs at the level of the HTT DNA itself. These DNA repair proteins are known from model systems to promote ongoing somatic CAG repeat expansions in tissues affected by HD. Thus, for triplet repeats, some DNA repair proteins seem to abandon their normal genoprotective roles and, instead, drive expansions and accelerate disease. One attractive hypothesis—still to be proven rigorously—is that somatic HTT expansions augment the disease burden of the inherited allele. If so, therapeutic approaches that lower levels of huntingtin protein may need blending with additional therapies that reduce levels of somatic CAG repeat expansions to achieve maximal effect.
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10
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Wright GEB, Black HF, Collins JA, Gall-Duncan T, Caron NS, Pearson CE, Hayden MR. Interrupting sequence variants and age of onset in Huntington's disease: clinical implications and emerging therapies. Lancet Neurol 2020; 19:930-939. [PMID: 33098802 DOI: 10.1016/s1474-4422(20)30343-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/23/2020] [Accepted: 08/25/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Huntington's disease is a fatal neurodegenerative disorder that is caused by CAG-CAA repeat expansion, encoding polyglutamine, in the huntingtin (HTT) gene. Current age-of-clinical-onset prediction models for Huntington's disease are based on polyglutamine length and explain only a proportion of the variability in age of onset observed between patients. These length-based assays do not interrogate the underlying genetic variation, because known genetic variants in this region do not alter the protein coding sequence. Given that individuals with identical repeat lengths can present with Huntington's disease decades apart, the search for genetic modifiers of clinical age of onset has become an active area of research. RECENT DEVELOPMENTS Results from three independent genetic studies of Huntington's disease have shown that glutamine-encoding CAA variants that interrupt DNA CAG repeat tracts, but do not alter polyglutamine length or polyglutamine homogeneity, are associated with substantial differences in age of onset of Huntington's disease in carriers. A variant that results in the loss of CAA interruption is associated with early onset and is particularly relevant to individuals that carry alleles in the reduced penetrance range (ie, CAG 36-39). Approximately a third of clinically manifesting carriers of reduced penetrance alleles, defined by current diagnostics, carry this variant. Somatic repeat instability, modified by interrupted CAG tracts, is the most probable cause mediating this effect. This relationship is supported by genome-wide screens for disease modifiers, which have revealed the importance of DNA-repair genes in Huntington's disease (ie, FAN1, LIG1, MLH1, MSH3, PMS1, and PMS2). WHERE NEXT?: Focus needs to be placed on refining our understanding of the effect of the loss-of-interruption and duplication-of-interruption variants and other interrupting sequence variants on age of onset, and assessing their effect in disease-relevant brain tissues, as well as in diverse population groups, such as individuals from Africa and Asia. Diagnostic tests should be augmented or updated, since current tests do not assess the underlying DNA sequence variation, especially when assessing individuals that carry alleles in the reduced penetrance range. Future studies should explore somatic repeat instability and DNA repair as new therapeutic targets to modify age of onset in Huntington's disease and in other repeat-mediated disorders. Disease-modifying therapies could potentially be developed by therapeutically targeting these processes. Promising approaches include therapeutically targeting the expanded repeat or directly perturbing key DNA-repair genes (eg, with antisense oligonucleotides or small molecules). Targeting the CAG repeat directly with naphthyridine-azaquinolone, a compound that induces contractions, and altering the expression of MSH3, represent two viable therapeutic strategies. However, as a first step, the capability of such novel therapeutic approaches to delay clinical onset in animal models should be assessed.
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Affiliation(s)
- Galen E B Wright
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada; Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | - Hailey Findlay Black
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada
| | - Jennifer A Collins
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada
| | - Terence Gall-Duncan
- Program of Genetics and Genome Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Nicholas S Caron
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada
| | - Christopher E Pearson
- Program of Genetics and Genome Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, ON, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada.
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Feasibility and initial validation of 'HD-Mobile', a smartphone application for remote self-administration of performance-based cognitive measures in Huntington's disease. J Neurol 2020; 268:590-601. [PMID: 32880724 DOI: 10.1007/s00415-020-10169-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 07/29/2020] [Accepted: 08/13/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Smartphone-based cognitive assessment measures allow efficient, rapid, and convenient collection of cognitive datasets. Establishment of feasibility and validity is essential for the widespread use of this approach. We describe a novel smartphone application (HD-Mobile) that includes three performance-based cognitive tasks with four key outcome measures, for use with Huntington's disease (HD) samples. We describe known groups and concurrent validity, test-retest reliability, sensitivity, and feasibility properties of the tasks. METHODS Forty-two HD CAG-expanded participants (20 manifest, 22 premanifest) and 28 healthy controls completed HD-Mobile cognitive tasks three times across an 8-day period, on days 1, 4, and 8. A subsample of participants had pen-and-paper cognitive task data available from their most recent assessment from their participation in a separate observational longitudinal study, Enroll-HD. RESULTS Manifest-HD participants performed worse than healthy controls for three of four HD-Mobile cognitive measures, and worse than premanifest-HD participants for two of four measures. We found robust test-retest reliability for manifest-HD participants (ICC = 0.71-0.96) and with some exceptions, in premanifest-HD (ICC = 0.52-0.96) and healthy controls (0.54-0.96). Correlations between HD-Mobile and selected Enroll-HD cognitive tasks were mostly medium to strong (r = 0.36-0.68) as were correlations between HD-Mobile cognitive tasks and measures of expected disease progression and motor symptoms for the HD CAG-expanded participants (r = - 0.34 to - 0.54). CONCLUSIONS Results indicated robust known-groups, test-retest, concurrent validity, and sensitivity of HD-Mobile cognitive tasks. The study demonstrates the feasibility and utility of HD-Mobile for conducting convenient, frequent, and potentially ongoing assessment of HD samples without the need for in-person assessment.
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12
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Sisodiya SM. Precision medicine and therapies of the future. Epilepsia 2020; 62 Suppl 2:S90-S105. [PMID: 32776321 PMCID: PMC8432144 DOI: 10.1111/epi.16539] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/20/2020] [Accepted: 04/21/2020] [Indexed: 12/24/2022]
Abstract
Precision medicine in the epilepsies has gathered much attention, especially with gene discovery pushing forward new understanding of disease biology. Several targeted treatments are emerging, some with considerable sophistication and individual‐level tailoring. There have been rare achievements in improving short‐term outcomes in a few very select patients with epilepsy. The prospects for further targeted, repurposed, or novel treatments seem promising. Along with much‐needed success, difficulties are also arising. Precision treatments do not always work, and sometimes are inaccessible or do not yet exist. Failures of precision medicine may not find their way to broader scrutiny. Precision medicine is not a new concept: It has been boosted by genetics and is often focused on genetically determined epilepsies, typically considered to be driven in an individual by a single genetic variant. Often the mechanisms generating the full clinical phenotype from such a perceived single cause are incompletely understood. The impact of additional genetic variation and other factors that might influence the clinical presentation represent complexities that are not usually considered. Precision success and precision failure are usually equally incompletely explained. There is a need for more comprehensive evaluation and a more rigorous framework, bringing together information that is both necessary and sufficient to explain clinical presentation and clinical responses to precision treatment in a precision approach that considers the full picture not only of the effects of a single variant, but also of its genomic and other measurable environment, within the context of the whole person. As we may be on the brink of a treatment revolution, progress must be considered and reasoned: One possible framework is proposed for the evaluation of precision treatments.
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Affiliation(s)
- Sanjay M Sisodiya
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK.,Chalfont Centre for Epilepsy, Bucks, UK
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13
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Kim KH, Hong EP, Shin JW, Chao MJ, Loupe J, Gillis T, Mysore JS, Holmans P, Jones L, Orth M, Monckton DG, Long JD, Kwak S, Lee R, Gusella JF, MacDonald ME, Lee JM. Genetic and Functional Analyses Point to FAN1 as the Source of Multiple Huntington Disease Modifier Effects. Am J Hum Genet 2020; 107:96-110. [PMID: 32589923 DOI: 10.1016/j.ajhg.2020.05.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/18/2020] [Indexed: 01/04/2023] Open
Abstract
A recent genome-wide association study of Huntington disease (HD) implicated genes involved in DNA maintenance processes as modifiers of onset, including multiple genome-wide significant signals in a chr15 region containing the DNA repair gene Fanconi-Associated Nuclease 1 (FAN1). Here, we have carried out detailed genetic, molecular, and cellular investigation of the modifiers at this locus. We find that missense changes within or near the DNA-binding domain (p.Arg507His and p.Arg377Trp) reduce FAN1's DNA-binding activity and its capacity to rescue mitomycin C-induced cytotoxicity, accounting for two infrequent onset-hastening modifier signals. We also idenified a third onset-hastening modifier signal whose mechanism of action remains uncertain but does not involve an amino acid change in FAN1. We present additional evidence that a frequent onset-delaying modifier signal does not alter FAN1 coding sequence but is associated with increased FAN1 mRNA expression in the cerebral cortex. Consistent with these findings and other cellular overexpression and/or suppression studies, knockout of FAN1 increased CAG repeat expansion in HD-induced pluripotent stem cells. Together, these studies support the process of somatic CAG repeat expansion as a therapeutic target in HD, and they clearly indicate that multiple genetic variations act by different means through FAN1 to influence HD onset in a manner that is largely additive, except in the rare circumstance that two onset-hastening alleles are present. Thus, an individual's particular combination of FAN1 haplotypes may influence their suitability for HD clinical trials, particularly if the therapeutic agent aims to reduce CAG repeat instability.
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Khristich AN, Mirkin SM. On the wrong DNA track: Molecular mechanisms of repeat-mediated genome instability. J Biol Chem 2020; 295:4134-4170. [PMID: 32060097 PMCID: PMC7105313 DOI: 10.1074/jbc.rev119.007678] [Citation(s) in RCA: 161] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Expansions of simple tandem repeats are responsible for almost 50 human diseases, the majority of which are severe, degenerative, and not currently treatable or preventable. In this review, we first describe the molecular mechanisms of repeat-induced toxicity, which is the connecting link between repeat expansions and pathology. We then survey alternative DNA structures that are formed by expandable repeats and review the evidence that formation of these structures is at the core of repeat instability. Next, we describe the consequences of the presence of long structure-forming repeats at the molecular level: somatic and intergenerational instability, fragility, and repeat-induced mutagenesis. We discuss the reasons for gender bias in intergenerational repeat instability and the tissue specificity of somatic repeat instability. We also review the known pathways in which DNA replication, transcription, DNA repair, and chromatin state interact and thereby promote repeat instability. We then discuss possible reasons for the persistence of disease-causing DNA repeats in the genome. We describe evidence suggesting that these repeats are a payoff for the advantages of having abundant simple-sequence repeats for eukaryotic genome function and evolvability. Finally, we discuss two unresolved fundamental questions: (i) why does repeat behavior differ between model systems and human pedigrees, and (ii) can we use current knowledge on repeat instability mechanisms to cure repeat expansion diseases?
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Affiliation(s)
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, Massachusetts 02155.
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15
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Alexander-Floyd J, Haroon S, Ying M, Entezari AA, Jaeger C, Vermulst M, Gidalevitz T. Unexpected cell type-dependent effects of autophagy on polyglutamine aggregation revealed by natural genetic variation in C. elegans. BMC Biol 2020; 18:18. [PMID: 32093691 PMCID: PMC7038566 DOI: 10.1186/s12915-020-0750-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 02/13/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Monogenic protein aggregation diseases, in addition to cell selectivity, exhibit clinical variation in the age of onset and progression, driven in part by inter-individual genetic variation. While natural genetic variants may pinpoint plastic networks amenable to intervention, the mechanisms by which they impact individual susceptibility to proteotoxicity are still largely unknown. RESULTS We have previously shown that natural variation modifies polyglutamine (polyQ) aggregation phenotypes in C. elegans muscle cells. Here, we find that a genomic locus from C. elegans wild isolate DR1350 causes two genetically separable aggregation phenotypes, without changing the basal activity of muscle proteostasis pathways known to affect polyQ aggregation. We find that the increased aggregation phenotype was due to regulatory variants in the gene encoding a conserved autophagy protein ATG-5. The atg-5 gene itself conferred dosage-dependent enhancement of aggregation, with the DR1350-derived allele behaving as hypermorph. Surprisingly, increased aggregation in animals carrying the modifier locus was accompanied by enhanced autophagy activation in response to activating treatment. Because autophagy is expected to clear, not increase, protein aggregates, we activated autophagy in three different polyQ models and found a striking tissue-dependent effect: activation of autophagy decreased polyQ aggregation in neurons and intestine, but increased it in the muscle cells. CONCLUSIONS Our data show that cryptic natural variants in genes encoding proteostasis components, although not causing detectable phenotypes in wild-type individuals, can have profound effects on aggregation-prone proteins. Clinical applications of autophagy activators for aggregation diseases may need to consider the unexpected divergent effects of autophagy in different cell types.
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Affiliation(s)
- J Alexander-Floyd
- Biology Department, Drexel University, Philadelphia, PA, 19104, USA
- Present Address: Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - S Haroon
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - M Ying
- Biology Department, Drexel University, Philadelphia, PA, 19104, USA
| | - A A Entezari
- Biology Department, Drexel University, Philadelphia, PA, 19104, USA
- Current Address: Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - C Jaeger
- Biology Department, Drexel University, Philadelphia, PA, 19104, USA
- Current Address: Department of Neuroradiology, Technical University of Munich, Munich, Germany
| | - M Vermulst
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Current Address: Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, 90089, USA
| | - T Gidalevitz
- Biology Department, Drexel University, Philadelphia, PA, 19104, USA.
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Williams GM, Petrides AK, Balakrishnan L, Surtees JA. Tracking Expansions of Stable and Threshold Length Trinucleotide Repeat Tracts In Vivo and In Vitro Using Saccharomyces cerevisiae. Methods Mol Biol 2020; 2056:25-68. [PMID: 31586340 DOI: 10.1007/978-1-4939-9784-8_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Trinucleotide repeat (TNR) tracts are inherently unstable during DNA replication, leading to repeat expansions and/or contractions. Expanded tracts are the cause of over 40 neurodegenerative and neuromuscular diseases. In this chapter, we focus on the (CAG)n and (CTG)n repeat sequences that, when expanded, lead to Huntington's disease (HD) and myotonic dystrophy type 1 (DM1), respectively, as well as a number of other neurodegenerative diseases. TNR tracts in most individuals are relatively small and stable in terms of length. However, TNR tracts become increasingly prone to expansion as tract length increases, eventually leading to very long tracts that disrupt coding (e.g. HD) or noncoding (e.g., DM1) regions of the genome. It is important to understand the early stages in TNR expansions, that is, the transition from small, stable lengths to susceptible threshold lengths. We describe PCR-based in vivo assays, using the model system Saccharomyces cerevisiae, to determine and characterize the dynamic behavior of TNR tracts in the stable and threshold ranges. We also describe a simple in vitro system to assess tract dynamics during 5' single-stranded DNA (ssDNA) flap processing and to assess the role of different DNA metabolism proteins in these dynamics. These assays can ultimately be used to determine factors that influence the early stages of TNR tract expansion.
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Affiliation(s)
- Gregory M Williams
- Centre for Chromosome Biology, National University of Ireland, Galway, Galway, Ireland
- Galway Neuroscience Centre, National Universityof Ireland, Galway, Galway, Ireland
| | | | - Lata Balakrishnan
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, USA
| | - Jennifer A Surtees
- Department of Biochemistry, JacobsSchool of Medicine and BiomedicalSciences, State University of New York atBuffalo, Buffalo, NY, USA.
- Genetics, Genomics and Bioinformatics Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, USA.
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17
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Lee JM, Correia K, Loupe J, Kim KH, Barker D, Hong EP, Chao MJ, Long JD, Lucente D, Vonsattel JPG, Pinto RM, Abu Elneel K, Ramos EM, Mysore JS, Gillis T, Wheeler VC, MacDonald ME, Gusella JF, McAllister B, Massey T, Medway C, Stone TC, Hall L, Jones L, Holmans P, Kwak S, Ehrhardt AG, Sampaio C, Ciosi M, Maxwell A, Chatzi A, Monckton DG, Orth M, Landwehrmeyer GB, Paulsen JS, Dorsey ER, Shoulson I, Myers RH. CAG Repeat Not Polyglutamine Length Determines Timing of Huntington's Disease Onset. Cell 2019; 178:887-900.e14. [PMID: 31398342 PMCID: PMC6700281 DOI: 10.1016/j.cell.2019.06.036] [Citation(s) in RCA: 291] [Impact Index Per Article: 58.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 04/08/2019] [Accepted: 06/27/2019] [Indexed: 01/27/2023]
Abstract
Variable, glutamine-encoding, CAA interruptions indicate that a property of the uninterrupted HTT CAG repeat sequence, distinct from the length of huntingtin's polyglutamine segment, dictates the rate at which Huntington's disease (HD) develops. The timing of onset shows no significant association with HTT cis-eQTLs but is influenced, sometimes in a sex-specific manner, by polymorphic variation at multiple DNA maintenance genes, suggesting that the special onset-determining property of the uninterrupted CAG repeat is a propensity for length instability that leads to its somatic expansion. Additional naturally occurring genetic modifier loci, defined by GWAS, may influence HD pathogenesis through other mechanisms. These findings have profound implications for the pathogenesis of HD and other repeat diseases and question the fundamental premise that polyglutamine length determines the rate of pathogenesis in the "polyglutamine disorders."
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18
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Nair RR, Corrochano S, Gasco S, Tibbit C, Thompson D, Maduro C, Ali Z, Fratta P, Arozena AA, Cunningham TJ, Fisher EMC. Uses for humanised mouse models in precision medicine for neurodegenerative disease. Mamm Genome 2019; 30:173-191. [PMID: 31203387 PMCID: PMC6759662 DOI: 10.1007/s00335-019-09807-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 05/11/2019] [Indexed: 12/11/2022]
Abstract
Neurodegenerative disease encompasses a wide range of disorders afflicting the central and peripheral nervous systems and is a major unmet biomedical need of our time. There are very limited treatments, and no cures, for most of these diseases, including Alzheimer's Disease, Parkinson's Disease, Huntington Disease, and Motor Neuron Diseases. Mouse and other animal models provide hope by analysing them to understand pathogenic mechanisms, to identify drug targets, and to develop gene therapies and stem cell therapies. However, despite many decades of research, virtually no new treatments have reached the clinic. Increasingly, it is apparent that human heterogeneity within clinically defined neurodegenerative disorders, and between patients with the same genetic mutations, significantly impacts disease presentation and, potentially, therapeutic efficacy. Therefore, stratifying patients according to genetics, lifestyle, disease presentation, ethnicity, and other parameters may hold the key to bringing effective therapies from the bench to the clinic. Here, we discuss genetic and cellular humanised mouse models, and how they help in defining the genetic and environmental parameters associated with neurodegenerative disease, and so help in developing effective precision medicine strategies for future healthcare.
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Affiliation(s)
- Remya R Nair
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK
| | - Silvia Corrochano
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK
| | - Samanta Gasco
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK
| | - Charlotte Tibbit
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK
| | - David Thompson
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK
| | - Cheryl Maduro
- Department of Neuromuscular Diseases, Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Zeinab Ali
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK
| | - Pietro Fratta
- Department of Neuromuscular Diseases, Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Abraham Acevedo Arozena
- Unidad de Investigación Hospital Universitario de Canarias, FUNCANIS, Instituto de Tecnologías Biomédicas ULL, and CIBERNED, La Laguna, 38320, Tenerife, Spain
| | | | - Elizabeth M C Fisher
- Mammalian Genetics Unit, MRC Harwell Institute, Oxfordshire, OX11 0RD, UK.
- Department of Neuromuscular Diseases, Institute of Neurology, University College London, London, WC1N 3BG, UK.
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19
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Rudenko O, Springer C, Skov LJ, Madsen AN, Hasholt L, Nørremølle A, Holst B. Ghrelin-mediated improvements in the metabolic phenotype in the R6/2 mouse model of Huntington's disease. J Neuroendocrinol 2019; 31:e12699. [PMID: 30776164 DOI: 10.1111/jne.12699] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/17/2019] [Accepted: 02/14/2019] [Indexed: 12/18/2022]
Abstract
Huntington's disease (HD) is a heritable neurodegenerative disorder, characterised by metabolic disturbances, along with cognitive and psychiatric impairments. Targeting metabolic HD dysfunction via the maintenance of body weight and fat mass and restoration of peripheral energy metabolism can improve the progression of neurological symptoms. In this respect, we focused on the therapeutic potential of the orexigenic peptide hormone ghrelin, which plays an important role in promoting a positive energy balance. In the present study, we found a significant disruption of circadian metabolic regulation in a R6/2 mouse HD model in the late stage of disease. Daily circadian rhythms of activity, energy expenditure, respiratory exchange ratio and feeding were strongly attenuated in R6/2 mice. During the rest phase, R6/2 mice had a higher total activity, elevated energy expenditure and excessive water consumption compared to control mice. We also found that, in the late stage of disease, R6/2 mice had ghrelin axis deficiency as a result of low circulating ghrelin levels, in addition to down-regulation of the ghrelin receptor and several key signalling molecules in the hypothalamus, as well as a reduced responsiveness to exogenous peripheral ghrelin. We demonstrated that, in pre-symptomatic mice, responsiveness to ghrelin is preserved. Chronic ghrelin treatment efficiently increased lean body mass and decreased the energy expenditure and fat utilisation of R6/2 mice in the early stage of disease. In addition, ghrelin treatment was also effective in the normalisation of drinking behaviour and the rest activity of these mice. Ghrelin treatment could provide a novel therapeutic possibility for delaying disease progression; however, deficiency in ghrelin receptor expression could limit its therapeutic potential in the late stage of disease.
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Affiliation(s)
- Olga Rudenko
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Cecilie Springer
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Louisa J Skov
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Andreas N Madsen
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Lis Hasholt
- Medical Genetics Program, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anne Nørremølle
- Medical Genetics Program, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Birgitte Holst
- Laboratory for Molecular Pharmacology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
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Kaemmerer WF, Grondin RC. The effects of huntingtin-lowering: what do we know so far? Degener Neurol Neuromuscul Dis 2019; 9:3-17. [PMID: 30881191 PMCID: PMC6413743 DOI: 10.2147/dnnd.s163808] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Therapies targeting mutant huntingtin DNA, mRNA, and protein have a chance at becoming the first disease-modifying treatments for Huntington’s disease, a fatal inherited neurodegenerative disorder for which only symptom management treatments are available today. This review focuses on evidence addressing several key questions pertinent to huntingtin-lowering, ranging from the functions of wild-type huntingtin (wtHTT) that may be disrupted by huntingtin-lowering treatments through the various ways huntingtin can be lowered, the tolerability of wtHTT-lowering in mice and primates, what has been found in the Ionis Pharmaceutical safety trial of a huntingtin-lowering therapy, and to the question of how much mutant huntingtin may need to be lowered for a therapy to be clinically effective. We conclude that adverse consequences of lowering wtHTT in animals appear to be brain region-specific, and/or dependent upon the animal’s stage of development and the amount by which huntingtin is lowered. Therefore, safe approaches to huntingtin-lowering in patients may be to lower huntingtin only moderately, or lower huntingtin only in the most affected brain regions, or lower huntingtin allele-selectively, or all of the above. Many additional questions about huntingtin-lowering remain open, and will only be answered by upcoming clinical trials, such as whether the delivery approaches currently planned will be adequate to get the treatment to the necessary brain regions, and whether non-allele-selective huntingtin-lowering will be safe in the long run. Meantime, there is a role for preclinical research to address key knowledge gaps, including the effects of non-allele-selective huntingtin-lowering on protein trafficking and viability at the cellular level, the tolerability of wtHTT-lowering in the corticostriatal connections of the primate brain, and the effects of this lowering on the functioning of neurotransmitter systems and the transport of neurotrophic factors to the striatum.
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Affiliation(s)
| | - Richard C Grondin
- Department of Neuroscience, University of Kentucky Medical Center, Lexington, KY, USA,
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21
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Long JD, Mills JA. Joint modeling of multivariate longitudinal data and survival data in several observational studies of Huntington's disease. BMC Med Res Methodol 2018; 18:138. [PMID: 30445915 PMCID: PMC6240282 DOI: 10.1186/s12874-018-0592-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 10/29/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Joint modeling is appropriate when one wants to predict the time to an event with covariates that are measured longitudinally and are related to the event. An underlying random effects structure links the survival and longitudinal submodels and allows for individual-specific predictions. Multiple time-varying and time-invariant covariates can be included to potentially increase prediction accuracy. The goal of this study was to estimate a multivariate joint model on several longitudinal observational studies of Huntington's disease, examine external validity performance, and compute individual-specific predictions for characterizing disease progression. Emphasis was on the survival submodel for predicting the hazard of motor diagnosis. METHODS Data from four observational studies was analyzed: Enroll-HD, PREDICT-HD, REGISTRY, and Track-HD. A Bayesian approach to estimation was adopted, and external validation was performed using a time-varying AUC measure. Individual-specific cumulative hazard predictions were computed based on a simulation approach. The cumulative hazard was used for computing predicted age of motor onset and also for a deviance residual indicating the discrepancy between observed diagnosis status and model-based status. RESULTS The joint model trained in a single study had very good performance in discriminating among diagnosed and pre-diagnosed participants in the remaining test studies, with the 5-year mean AUC = .83 (range .77-.90), and the 10-year mean AUC = .86 (range .82-.92). Graphical analysis of the predicted age of motor diagnosis showed an expected strong relationship with the trinucleotide expansion that causes Huntington's disease. Graphical analysis of the deviance-type residual revealed there were individuals who converted to a diagnosis despite having relatively low model-based risk, others who had not yet converted despite having relatively high risk, and the majority falling between the two extremes. CONCLUSIONS Joint modeling is an improvement over traditional survival modeling because it considers all the longitudinal observations of covariates that are predictive of an event. Predictions from joint models can have greater accuracy because they are tailored to account for individual variability. These predictions can provide relatively accurate characterizations of individual disease progression, which might be important in the timing of interventions, determining the qualification for appropriate clinical trials, and general genotypic analysis.
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Affiliation(s)
- Jeffrey D. Long
- Department of Psychiatry, Carver College of Medicine, University of Iowa, 500 Newton Road, Iowa City, IA 52242-1000 USA
- Department of Biostatistics, Department of Public Health, University of Iowa, 145 N. Riverside Drive, Iowa City, IA 52242-1000 USA
| | - James A. Mills
- Department of Psychiatry, Carver College of Medicine, University of Iowa, 500 Newton Road, Iowa City, IA 52242-1000 USA
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