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Meisl G, Xu CK, Taylor JD, Michaels TCT, Levin A, Otzen D, Klenerman D, Matthews S, Linse S, Andreasen M, Knowles TPJ. Uncovering the universality of self-replication in protein aggregation and its link to disease. SCIENCE ADVANCES 2022; 8:eabn6831. [PMID: 35960802 PMCID: PMC9374340 DOI: 10.1126/sciadv.abn6831] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Fibrillar protein aggregates are a hallmark of a range of human disorders, from prion diseases to dementias, but are also encountered in several functional contexts. Yet, the fundamental links between protein assembly mechanisms and their functional or pathological roles have remained elusive. Here, we analyze the aggregation kinetics of a large set of proteins that self-assemble by a nucleated-growth mechanism, from those associated with disease, over those whose aggregates fulfill functional roles in biology, to those that aggregate only under artificial conditions. We find that, essentially, all such systems, regardless of their biological role, are capable of self-replication. However, for aggregates that have evolved to fulfill a structural role, the rate of self-replication is too low to be significant on the biologically relevant time scale. By contrast, all disease-related proteins are able to self-replicate quickly compared to the time scale of the associated disease. Our findings establish the ubiquity of self-replication and point to its potential importance across aggregation-related disorders.
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Affiliation(s)
- Georg Meisl
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Catherine K. Xu
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Jonathan D. Taylor
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Thomas C. T. Michaels
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Aviad Levin
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Daniel Otzen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, Aarhus DK-8000, Denmark
| | - David Klenerman
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
- U.K. Dementia Research Institute, University of Cambridge, Cambridge CB2 0XY, UK
| | - Steve Matthews
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Sara Linse
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
- Corresponding author. (S.L.); (M.A.); (T.P.J.K.)
| | - Maria Andreasen
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, Aarhus DK-8000, Denmark
- Corresponding author. (S.L.); (M.A.); (T.P.J.K.)
| | - Tuomas P. J. Knowles
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
- Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK
- Corresponding author. (S.L.); (M.A.); (T.P.J.K.)
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Huntingtin Co-Isolates with Small Extracellular Vesicles from Blood Plasma of TgHD and KI-HD Pig Models of Huntington's Disease and Human Blood Plasma. Int J Mol Sci 2022; 23:ijms23105598. [PMID: 35628406 PMCID: PMC9147436 DOI: 10.3390/ijms23105598] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/12/2022] [Accepted: 05/15/2022] [Indexed: 12/16/2022] Open
Abstract
(1) Background: Huntington’s disease (HD) is rare incurable hereditary neurodegenerative disorder caused by CAG repeat expansion in the gene coding for the protein huntingtin (HTT). Mutated huntingtin (mHTT) undergoes fragmentation and accumulation, affecting cellular functions and leading to neuronal cell death. Porcine models of HD are used in preclinical testing of currently emerging disease modifying therapies. Such therapies are aimed at reducing mHTT expression, postpone the disease onset, slow down the progression, and point out the need of biomarkers to monitor disease development and therapy efficacy. Recently, extracellular vesicles (EVs), particularly exosomes, gained attention as possible carriers of disease biomarkers. We aimed to characterize HTT and mHTT forms/fragments in blood plasma derived EVs in transgenic (TgHD) and knock-in (KI-HD) porcine models, as well as in HD patients’ plasma. (2) Methods: Small EVs were isolated by ultracentrifugation and HTT forms were visualized by western blotting. (3) Results: The full length 360 kDa HTT co-isolated with EVs from both the pig model and HD patient plasma. In addition, a ~70 kDa mutant HTT fragment was specific for TgHD pigs. Elevated total huntingtin levels in EVs from plasma of HD groups compared to controls were observed in both pig models and HD patients, however only in TgHD were they significant (p = 0.02). (4) Conclusions: Our study represents a valuable initial step towards the characterization of EV content in the search for HD biomarkers.
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Caron NS, Anderson C, Black HF, Sanders SS, Lemarié FL, Doty CN, Hayden MR. Reliable Resolution of Full-Length Huntingtin Alleles by Quantitative Immunoblotting. J Huntingtons Dis 2021; 10:355-365. [PMID: 34092649 DOI: 10.3233/jhd-200463] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Therapeutics that lower mutant huntingtin (mHTT) have shown promise in preclinical studies and are in clinical development for the treatment of Huntington's disease (HD). Multiple assays have been developed that either quantify mHTT or total HTT but may not accurately measure levels of wild type HTT (wtHTT) in biological samples. OBJECTIVE To optimize a method that can be used to resolve, quantify and directly compare levels of full length wtHTT and mHTT in HD samples. METHODS We provide a detailed quantitative immunoblotting protocol to reproducibly resolve full length wtHTT and mHTT in multiple HD mouse and patient samples. RESULTS We show that this assay can be modified, depending on the sample, to resolve wtHTT and mHTT with a wide range of polyglutamine differences (ΔQs 22-179). We also demonstrate that this method can be used to quantify allele-selective lowering of mHTT using an antisense oligonucleotide in HD patient-derived cells. CONCLUSION This quantitative immunoblotting method can be used to reliably resolve full length HTT alleles with ΔQs≥22 and allows for direct comparison of wtHTT and mHTT levels in HD samples.
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Affiliation(s)
- Nicholas S Caron
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | | | - Hailey Findlay Black
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Shaun S Sanders
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.,Current address: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Fanny L Lemarié
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Crystal N Doty
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
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Cheong RY, Baldo B, Sajjad MU, Kirik D, Petersén Å. Effects of mutant huntingtin inactivation on Huntington disease-related behaviours in the BACHD mouse model. Neuropathol Appl Neurobiol 2021; 47:564-578. [PMID: 33330988 PMCID: PMC8247873 DOI: 10.1111/nan.12682] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/27/2020] [Accepted: 12/14/2020] [Indexed: 01/02/2023]
Abstract
AIMS Huntington disease (HD) is a fatal neurodegenerative disorder with no disease-modifying treatments approved so far. Ongoing clinical trials are attempting to reduce huntingtin (HTT) expression in the central nervous system (CNS) using different strategies. Yet, the distribution and timing of HTT-lowering therapies required for a beneficial clinical effect is less clear. Here, we investigated whether HD-related behaviours could be prevented by inactivating mutant HTT at different disease stages and to varying degrees in an experimental model. METHODS We generated mutant BACHD mice with either a widespread or circuit-specific inactivation of mutant HTT by using Cre recombinase (Cre) under the nestin promoter or the adenosine A2A receptor promoter respectively. We also simulated a clinical gene therapy scenario with allele-specific HTT targeting by injections of recombinant adeno-associated viral (rAAV) vectors expressing Cre into the striatum of adult BACHD mice. All mice were assessed using behavioural tests to investigate motor, metabolic and psychiatric outcome measures at 4-6 months of age. RESULTS While motor deficits, body weight changes, anxiety and depressive-like behaviours are present in BACHD mice, early widespread CNS inactivation during development significantly improves rotarod performance, body weight changes and depressive-like behaviour. However, conditional circuit-wide mutant HTT deletion from the indirect striatal pathway during development and focal striatal-specific deletion in adulthood failed to rescue any of the HD-related behaviours. CONCLUSIONS Our results indicate that widespread targeting and the timing of interventions aimed at reducing mutant HTT are important factors to consider when developing disease-modifying therapies for HD.
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Affiliation(s)
- Rachel Y. Cheong
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Barbara Baldo
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
- Present address:
Evotec SEHD Research and Translational SciencesHamburgGermany
| | - Muhammad U. Sajjad
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Deniz Kirik
- Brain Repair and Imaging in Neural Systems UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Åsa Petersén
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
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5
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Zhu D, Schieferecke AJ, Lopez PA, Schaffer DV. Adeno-Associated Virus Vector for Central Nervous System Gene Therapy. Trends Mol Med 2021; 27:524-537. [PMID: 33895085 DOI: 10.1016/j.molmed.2021.03.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 03/15/2021] [Accepted: 03/22/2021] [Indexed: 12/14/2022]
Abstract
The past several years have witnessed significant advances in the development of therapeutic gene delivery for neurological disorders of the central nervous system (CNS). In particular, genome-wide sequencing analysis has deepened our understanding of mutations that underlie many monogenic disorders, which in turn has contributed to clinical advances involving adeno-associated virus (AAV) vector delivery of replacement genes to treat recessive disorders. Moreover, gene therapy has been further bolstered with advances in genome editing tools that allow researchers to silence, repair, and amend endogenous genes. However, despite strong preclinical and clinical progress, challenges remain, including delivery and safety. Here, we discuss advances in AAV engineering, recent developments in cargo design, and translation of these technologies towards clinical progress.
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Affiliation(s)
- Danqing Zhu
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA
| | - Adam J Schieferecke
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | - Paola A Lopez
- Department of Bioengineering, University of California, Berkeley, CA, 94720, USA
| | - David V Schaffer
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA; Department of Bioengineering, University of California, Berkeley, CA, 94720, USA; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720, USA.
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6
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Przybyl L, Wozna-Wysocka M, Kozlowska E, Fiszer A. What, When and How to Measure-Peripheral Biomarkers in Therapy of Huntington's Disease. Int J Mol Sci 2021; 22:ijms22041561. [PMID: 33557131 PMCID: PMC7913877 DOI: 10.3390/ijms22041561] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 01/29/2021] [Accepted: 01/29/2021] [Indexed: 12/11/2022] Open
Abstract
Among the main challenges in further advancing therapeutic strategies for Huntington’s disease (HD) is the development of biomarkers which must be applied to assess the efficiency of the treatment. HD is a dreadful neurodegenerative disorder which has its source of pathogenesis in the central nervous system (CNS) but is reflected by symptoms in the periphery. Visible symptoms include motor deficits and slight changes in peripheral tissues, which can be used as hallmarks for prognosis of the course of HD, e.g., the onset of the disease symptoms. Knowing how the pathology develops in the context of whole organisms is crucial for the development of therapy which would be the most beneficial for patients, as well as for proposing appropriate biomarkers to monitor disease progression and/or efficiency of treatment. We focus here on molecular peripheral biomarkers which could be used as a measurable outcome of potential therapy. We present and discuss a list of wet biomarkers which have been proposed in recent years to measure pre- and postsymptomatic HD. Interestingly, investigation of peripheral biomarkers in HD can unravel new aspects of the disease pathogenesis. This especially refers to inflammatory proteins or specific immune cells which attract scientific attention in neurodegenerative disorders.
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Affiliation(s)
- Lukasz Przybyl
- Laboratory of Mammalian Model Organisms, Institute of Bioorganic Chemistry Polish Academy of Sciences, 61-704 Poznan, Poland
- Correspondence: (L.P.); (A.F.)
| | - Magdalena Wozna-Wysocka
- Department of Medical Biotechnology, Institute of Bioorganic Chemistry Polish Academy of Sciences, 61-704 Poznan, Poland; (M.W.-W.); (E.K.)
| | - Emilia Kozlowska
- Department of Medical Biotechnology, Institute of Bioorganic Chemistry Polish Academy of Sciences, 61-704 Poznan, Poland; (M.W.-W.); (E.K.)
| | - Agnieszka Fiszer
- Department of Medical Biotechnology, Institute of Bioorganic Chemistry Polish Academy of Sciences, 61-704 Poznan, Poland; (M.W.-W.); (E.K.)
- Correspondence: (L.P.); (A.F.)
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Landles C, Milton RE, Jean A, McLarnon S, McAteer SJ, Taxy BA, Osborne GF, Zhang C, Duan W, Howland D, Bates GP. Development of novel bioassays to detect soluble and aggregated Huntingtin proteins on three technology platforms. Brain Commun 2021; 3:fcaa231. [PMID: 33604571 PMCID: PMC7878250 DOI: 10.1093/braincomms/fcaa231] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/27/2020] [Accepted: 12/01/2020] [Indexed: 01/29/2023] Open
Abstract
Huntington's disease is caused by a CAG / polyglutamine repeat expansion. Mutated CAG repeats undergo somatic instability, resulting in tracts of several hundred CAGs in the brain; and genetic modifiers of Huntington's disease have indicated that somatic instability is a major driver of age of onset and disease progression. As the CAG repeat expands, the likelihood that exon 1 does not splice to exon 2 increases, resulting in two transcripts that encode full-length huntingtin protein, as well as the highly pathogenic and aggregation-prone exon 1 huntingtin protein. Strategies that target the huntingtin gene or transcripts are a major focus of therapeutic development. It is essential that the levels of all isoforms of huntingtin protein can be tracked, to better understand the molecular pathogenesis, and to assess the impact of huntingtin protein-lowering approaches in preclinical studies and clinical trials. Huntingtin protein bioassays for soluble and aggregated forms of huntingtin protein are in widespread use on the homogeneous time-resolved fluorescence and Meso Scale Discovery platforms, but these do not distinguish between exon 1 huntingtin protein and full-length huntingtin protein. In addition, they are frequently used to quantify huntingtin protein levels in the context of highly expanded polyglutamine tracts, for which appropriate protein standards do not currently exist. Here, we set out to develop novel huntingtin protein bioassays to ensure that all soluble huntingtin protein isoforms could be distinguished. We utilized the zQ175 Huntington's disease mouse model that has ∼190 CAGs, a CAG repeat size for which protein standards are not available. Initially, 30 combinations of six antibodies were tested on three technology platforms: homogeneous time-resolved fluorescence, amplified luminescent proximity homogeneous assay and Meso Scale Discovery, and a triage strategy was employed to select the best assays. We found that, without a polyglutamine-length-matched standard, the vast majority of soluble mutant huntingtin protein assays cannot be used for quantitative purposes, as the highly expanded polyglutamine tract decreased assay performance. The combination of our novel assays, with those already in existence, provides a tool-kit to track: total soluble mutant huntingtin protein, soluble exon 1 huntingtin protein, soluble mutant huntingtin protein (excluding the exon 1 huntingtin protein) and total soluble full-length huntingtin protein (mutant and wild type). Several novel aggregation assays were also developed that track with disease progression. These selected assays can be used to compare the levels of huntingtin protein isoforms in a wide variety of mouse models of Huntington's disease and to determine how these change in response to genetic or therapeutic manipulations.
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Affiliation(s)
- Christian Landles
- Department of Neurodegenerative Disease, Huntington’s Disease Centre, UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London, UK
| | - Rebecca E Milton
- Department of Neurodegenerative Disease, Huntington’s Disease Centre, UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London, UK
| | | | | | - Sean J McAteer
- Department of Neurodegenerative Disease, Huntington’s Disease Centre, UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London, UK
| | - Bridget A Taxy
- Department of Neurodegenerative Disease, Huntington’s Disease Centre, UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London, UK
| | - Georgina F Osborne
- Department of Neurodegenerative Disease, Huntington’s Disease Centre, UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London, UK
| | - Chuangchuang Zhang
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Wenzhen Duan
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David Howland
- CHDI Management/CHDI Foundation Inc., New York, NY, USA
| | - Gillian P Bates
- Department of Neurodegenerative Disease, Huntington’s Disease Centre, UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London, UK
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Gosset P, Maxan A, Alpaugh M, Breger L, Dehay B, Tao Z, Ling Z, Qin C, Cisbani G, Fortin N, Vonsattel JPG, Lacroix S, Oueslati A, Bezard E, Cicchetti F. Evidence for the spread of human-derived mutant huntingtin protein in mice and non-human primates. Neurobiol Dis 2020; 141:104941. [PMID: 32422281 DOI: 10.1016/j.nbd.2020.104941] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/15/2020] [Accepted: 05/05/2020] [Indexed: 02/05/2023] Open
Abstract
In recent years, substantial evidence has emerged to suggest that spreading of pathological proteins contributes to disease pathology in numerous neurodegenerative disorders. Work from our laboratory and others have shown that, despite its strictly genetic nature, Huntington's disease (HD) may be another condition in which this mechanism contributes to pathology. In this study, we set out to determine if the mutant huntingtin protein (mHTT) present in post-mortem brain tissue derived from HD patients can induce pathology in mice and/or non-human primates. For this, we performed three distinct sets of experiments where homogenates were injected into the brains of adult a) Wild-type (WT) and b) BACHD mice or c) non-human primates. Neuropathological assessments revealed that, while changes in the endogenous huntingtin were not apparent, mHTT could spread between cellular elements and brain structures. Furthermore, behavioural differences only occurred in the animal model of HD which already overexpressed mHTT. Taken together, our results indicate that mHTT derived from human brains has only a limited capacity to propagate between cells and does not depict prion-like characteristics. This contrasts with recent work demonstrating that other forms of mHTT - such as fibrils of a pathological polyQ length or fibroblasts and induced pluripotent stem cells derived from HD cases - can indeed disseminate disease throughout the brain in a prion-like fashion.
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Affiliation(s)
- Philippe Gosset
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada
| | - Alexander Maxan
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada
| | - Melanie Alpaugh
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada
| | - Ludivine Breger
- Université de Bordeaux, Institut des maladies neurodégénératives, UMR 5293, Bordeaux CNRS UMR 5293, France
| | - Benjamin Dehay
- Université de Bordeaux, Institut des maladies neurodégénératives, UMR 5293, Bordeaux CNRS UMR 5293, France
| | - Zhu Tao
- Institute of Laboratory Animal Sciences, China Academy of Medical Sciences, Beijing, China
| | - Zhang Ling
- Institute of Laboratory Animal Sciences, China Academy of Medical Sciences, Beijing, China
| | - Chuan Qin
- Institute of Laboratory Animal Sciences, China Academy of Medical Sciences, Beijing, China.
| | - Giulia Cisbani
- University of Toronto, Department of Nutritional Sciences, Toronto, ON M5S 1A8, Canada
| | - Nadia Fortin
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada
| | | | - Steve Lacroix
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada; Département de Médicine Moléculaire, Université Laval, Québec, QC G1K 0A6, Canada
| | - Abid Oueslati
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada; Département de Médicine Moléculaire, Université Laval, Québec, QC G1K 0A6, Canada
| | - Erwan Bezard
- Université de Bordeaux, Institut des maladies neurodégénératives, UMR 5293, Bordeaux CNRS UMR 5293, France
| | - Francesca Cicchetti
- Centre de Recherche du CHU de Québec - Université Laval, Axe Neurosciences, Québec, QC G1V 4G2, Canada; Département de Psychiatrie & Neurosciences, Université Laval, Québec, QC G1K 0A6, Canada.
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9
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Assessing average somatic CAG repeat instability at the protein level. Sci Rep 2019; 9:19152. [PMID: 31844074 PMCID: PMC6915696 DOI: 10.1038/s41598-019-55202-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 11/18/2019] [Indexed: 12/25/2022] Open
Abstract
Sandwich ELISA-based methods use Abs that target the expanded polyglutamine (polyQ) tract to quantify mutant huntingtin (mHTT). Using Meso Scale Discovery (MSD) assay, the mHTT signal detected with MW1 Ab correlated with polyQ length and doubled with a difference of only 7 glutamine residues between equivalent amounts of purified mHTTexon1 proteins. Similar polyQ length-dependent effects on MSD signals were confirmed using endogenous full length mHTT from brains of Huntington’s disease (HD) knock-in (KI) mice. We used this avidity bias to devise a method to assess average CAG repeat instability at the protein level in a mixed population of HTT proteins present in tissues. Signal detected for average polyQ length quantification at the protein level by our method exhibited a strong correlation with average CAG repeat length at the genomic DNA level determined by PCR method in striatal tissue homogenates from HdhQ140 KI mice and in human HD postmortem cortex. This work establishes that CAG repeat instability in mutant HTT is reflected at the protein level.
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