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Deng Y, Wang H, Joni M, Sekhri R, Reiner A. Progression of basal ganglia pathology in heterozygous Q175 knock-in Huntington's disease mice. J Comp Neurol 2021; 529:1327-1371. [PMID: 32869871 PMCID: PMC8049038 DOI: 10.1002/cne.25023] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 08/07/2020] [Accepted: 08/26/2020] [Indexed: 12/29/2022]
Abstract
We used behavioral testing and morphological methods to detail the progression of basal ganglia neuron type-specific pathology and the deficits stemming from them in male heterozygous Q175 mice, compared to age-matched WT males. A rotarod deficit was not present in Q175 mice until 18 months, but increased open field turn rate (reflecting hyperkinesia) and open field anxiety were evident at 6 months. No loss of striatal neurons was seen out to 18 months, but ENK+ and DARPP32+ striatal perikarya were fewer by 6 months, due to diminished expression, with further decline by 18 months. No reduction in SP+ striatal perikarya or striatal interneurons was seen in Q175 mice at 18 months, but cholinergic interneurons showed dendrite attenuation by 6 months. Despite reduced ENK expression in indirect pathway striatal perikarya, ENK-immunostained terminals in globus pallidus externus (GPe) were more abundant at 6 months and remained so out to 18 months. Similarly, SP-immunostained terminals from striatal direct pathway neurons were more abundant in globus pallidus internus and substantia nigra at 6 months and remained so at 18 months. FoxP2+ arkypallidal GPe neurons and subthalamic nucleus neurons were lost by 18 months but not prototypical PARV+ GPe neurons or dopaminergic nigral neurons. Our results show that striatal projection neuron abnormalities and behavioral abnormalities reflecting them develop between 2 and 6 months of age in Q175 male heterozygotes, indicating early effects of the HD mutation. The striatal pathologies resemble those in human HD, but are less severe at 18 months than even in premanifest HD.
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Affiliation(s)
- Yunping Deng
- Department of Anatomy and NeurobiologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Hongbing Wang
- Department of Anatomy and NeurobiologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Marion Joni
- Department of Anatomy and NeurobiologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Radhika Sekhri
- Department of PathologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Anton Reiner
- Department of Anatomy and NeurobiologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Department of OphthalmologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
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2
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Selective suppression of polyglutamine-expanded protein by lipid nanoparticle-delivered siRNA targeting CAG expansions in the mouse CNS. MOLECULAR THERAPY. NUCLEIC ACIDS 2021; 24:1-10. [PMID: 33738134 PMCID: PMC7937577 DOI: 10.1016/j.omtn.2021.02.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 02/09/2021] [Indexed: 12/11/2022]
Abstract
Polyglutamine (polyQ) diseases are inherited neurodegenerative disorders caused by expansion of cytosine-adenine-guanine (CAG)-trinucleotide repeats in causative genes. These diseases include spinal and bulbar muscular atrophy (SBMA), Huntington’s disease, dentatorubral-pallidoluysian atrophy, and spinocerebellar ataxias. Targeting expanded CAG repeats is a common therapeutic approach to polyQ diseases, but concomitant silencing of genes with normal CAG repeats may lead to toxicity. Previous studies have shown that CAG repeat-targeting small interfering RNA duplexes (CAG-siRNAs) have the potential to selectively suppress mutant proteins in in vitro cell models of polyQ diseases. However, in vivo application of these siRNAs has not yet been investigated. In this study, we demonstrate that an unlocked nucleic acid (UNA)-modified CAG-siRNA shows high selectivity for polyQ-expanded androgen receptor (AR) inhibition in in vitro cell models and that lipid nanoparticle (LNP)-mediated delivery of the CAG-siRNA selectively suppresses mutant AR in the central nervous system of an SBMA mouse model. In addition, a subcutaneous injection of the LNP-delivered CAG-siRNA efficiently suppresses mutant AR in the skeletal muscle of the SBMA mouse model. These results support the therapeutic potential of LNP-delivered UNA-modified CAG-siRNAs for selective suppression of mutant proteins in SBMA and other polyQ diseases.
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3
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Monckton DG. The Contribution of Somatic Expansion of the CAG Repeat to Symptomatic Development in Huntington's Disease: A Historical Perspective. J Huntingtons Dis 2021; 10:7-33. [PMID: 33579863 PMCID: PMC7990401 DOI: 10.3233/jhd-200429] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The discovery in the early 1990s of the expansion of unstable simple sequence repeats as the causative mutation for a number of inherited human disorders, including Huntington's disease (HD), opened up a new era of human genetics and provided explanations for some old problems. In particular, an inverse association between the number of repeats inherited and age at onset, and unprecedented levels of germline instability, biased toward further expansion, provided an explanation for the wide symptomatic variability and anticipation observed in HD and many of these disorders. The repeats were also revealed to be somatically unstable in a process that is expansion-biased, age-dependent and tissue-specific, features that are now increasingly recognised as contributory to the age-dependence, progressive nature and tissue specificity of the symptoms of HD, and at least some related disorders. With much of the data deriving from affected individuals, and model systems, somatic expansions have been revealed to arise in a cell division-independent manner in critical target tissues via a mechanism involving key components of the DNA mismatch repair pathway. These insights have opened new approaches to thinking about how the disease could be treated by suppressing somatic expansion and revealed novel protein targets for intervention. Exciting times lie ahead in turning these insights into novel therapies for HD and related disorders.
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Affiliation(s)
- Darren G. Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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4
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Donaldson J, Powell S, Rickards N, Holmans P, Jones L. What is the Pathogenic CAG Expansion Length in Huntington's Disease? J Huntingtons Dis 2021; 10:175-202. [PMID: 33579866 PMCID: PMC7990448 DOI: 10.3233/jhd-200445] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Huntington's disease (HD) (OMIM 143100) is caused by an expanded CAG repeat tract in the HTT gene. The inherited CAG length is known to expand further in somatic and germline cells in HD subjects. Age at onset of the disease is inversely correlated with the inherited CAG length, but is further modulated by a series of genetic modifiers which are most likely to act on the CAG repeat in HTT that permit it to further expand. Longer repeats are more prone to expansions, and this expansion is age dependent and tissue-specific. Given that the inherited tract expands through life and most subjects develop disease in mid-life, this implies that in cells that degenerate, the CAG length is likely to be longer than the inherited length. These findings suggest two thresholds- the inherited CAG length which permits further expansion, and the intracellular pathogenic threshold, above which cells become dysfunctional and die. This two-step mechanism has been previously proposed and modelled mathematically to give an intracellular pathogenic threshold at a tract length of 115 CAG (95% confidence intervals 70- 165 CAG). Empirically, the intracellular pathogenic threshold is difficult to determine. Clues from studies of people and models of HD, and from other diseases caused by expanded repeat tracts, place this threshold between 60- 100 CAG, most likely towards the upper part of that range. We assess this evidence and discuss how the intracellular pathogenic threshold in manifest disease might be better determined. Knowing the cellular pathogenic threshold would be informative for both understanding the mechanism in HD and deploying treatments.
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Affiliation(s)
- Jasmine Donaldson
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Sophie Powell
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Nadia Rickards
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Peter Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
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5
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Landles C, Milton RE, Ali N, Flomen R, Flower M, Schindler F, Gomez-Paredes C, Bondulich MK, Osborne GF, Goodwin D, Salsbury G, Benn CL, Sathasivam K, Smith EJ, Tabrizi SJ, Wanker EE, Bates GP. Subcellular Localization And Formation Of Huntingtin Aggregates Correlates With Symptom Onset And Progression In A Huntington'S Disease Model. Brain Commun 2020; 2:fcaa066. [PMID: 32954323 PMCID: PMC7425396 DOI: 10.1093/braincomms/fcaa066] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/02/2020] [Accepted: 04/13/2020] [Indexed: 12/12/2022] Open
Abstract
Huntington's disease is caused by the expansion of a CAG repeat within exon 1 of the HTT gene, which is unstable, leading to further expansion, the extent of which is brain region and peripheral tissue specific. The identification of DNA repair genes as genetic modifiers of Huntington's disease, that were known to abrogate somatic instability in Huntington's disease mouse models, demonstrated that somatic CAG expansion is central to disease pathogenesis, and that the CAG repeat threshold for pathogenesis in specific brain cells might not be known. We have previously shown that the HTT gene is incompletely spliced generating a small transcript that encodes the highly pathogenic exon 1 HTT protein. The longer the CAG repeat, the more of this toxic fragment is generated, providing a pathogenic consequence for somatic expansion. Here, we have used the R6/2 mouse model to investigate the molecular and behavioural consequences of expressing exon 1 HTT with 90 CAGs, a mutation that causes juvenile Huntington's disease, compared to R6/2 mice carrying ∼200 CAGs, a repeat expansion of a size rarely found in Huntington's disease patient's blood, but which has been detected in post-mortem brains as a consequence of somatic CAG repeat expansion. We show that nuclear aggregation occurred earlier in R6/2(CAG)90 mice and that this correlated with the onset of transcriptional dysregulation. Whereas in R6/2(CAG)200 mice, cytoplasmic aggregates accumulated rapidly and closely tracked with the progression of behavioural phenotypes and with end-stage disease. We find that aggregate species formed in the R6/2(CAG)90 brains have different properties to those in the R6/2(CAG)200 mice. Within the nucleus, they retain a diffuse punctate appearance throughout the course of the disease, can be partially solubilized by detergents and have a greater seeding potential in young mice. In contrast, aggregates from R6/2(CAG)200 brains polymerize into larger structures that appear as inclusion bodies. These data emphasize that a subcellular analysis, using multiple complementary approaches, must be undertaken in order to draw any conclusions about the relationship between HTT aggregation and the onset and progression of disease phenotypes.
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Affiliation(s)
- Christian Landles
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Rebecca E Milton
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Nadira Ali
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Rachel Flomen
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Michael Flower
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Franziska Schindler
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, 13125 Berlin, Germany and Berlin Institute of Health (BIH), 10178 Berlin, Germany
| | - Casandra Gomez-Paredes
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Marie K Bondulich
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Georgina F Osborne
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Daniel Goodwin
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Grace Salsbury
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Caroline L Benn
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK.,LoQus23 Therapeutics, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - Kirupa Sathasivam
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Edward J Smith
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Sarah J Tabrizi
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
| | - Erich E Wanker
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, 13125 Berlin, Germany and Berlin Institute of Health (BIH), 10178 Berlin, Germany
| | - Gillian P Bates
- Huntington's Disease Centre, Department of Neurodegenerative Disease and UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, UCL, Queen Square, WC1N 3BG, UK
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6
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Kielar C, Morton AJ. Early Neurodegeneration in R6/2 Mice Carrying the Huntington's Disease Mutation with a Super-Expanded CAG Repeat, Despite Normal Lifespan. J Huntingtons Dis 2019; 7:61-76. [PMID: 29480204 DOI: 10.3233/jhd-170265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The threshold of CAG repeat expansion in the HTT gene that causes HD is 36 CAG repeats, although 'superlong' expansions are found in individual neurons in postmortem brains. Previously, we showed that, compared to mice with <250 CAG repeats, onset of disease in R6/2 mice carrying superlong (>440) CAG repeat expansions was delayed, and disease progression was slower. Inclusion pathology also differed from 250 CAG repeat mice, being dominated by a novel kind of extranuclear neuronal inclusion (nENNI) that resembles a class of aggregate seen in patients with the adult onset form of HD. Here, we characterised neuropathology in R6/2 mice with >400 CAG repeats using light and electron microscopy. nENNIs were found with increased frequency and wider distribution with age. Some nENNIs appear to 'mature' as the disease develops, developing a multi-layered cored structure. Mice with superlong CAG repeats do not develop clinical signs until they are around 30-40 weeks of age, and they attain a normal life span (>2 years). Nevertheless, they show brain atrophy and unequivocal neuron loss from the striatum and cortex by 22 weeks of age, an age at which similar pathology is seen in 250 CAG repeat mice. Since this time-point is 'end stage' for a 250 CAG mouse, but very far (at least 18 months) from end stage for a > 440 CAG repeat mouse, our data confirm that the appearance of clinical signs, the formation of inclusions, and neurodegeneration are processes that progress independently. A better understanding of the relationship between CAG repeat length, neurodegenerative pathways, and clinical behavioural signs is essential, if we are to find strategies to delay or reverse the course of this disease.
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Affiliation(s)
- Catherine Kielar
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - A Jennifer Morton
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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7
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Ratna N, Jain S. Huntington's disease pig model: Squealing into the spotlight. Mov Disord 2018; 33:1410-1411. [DOI: 10.1002/mds.96] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 06/06/2018] [Accepted: 06/12/2018] [Indexed: 11/06/2022] Open
Affiliation(s)
- Nikhil Ratna
- Department of Clinical Neurosciences (Molecular Genetics Laboratory); National Institute of Mental Health and Neuro Sciences; Bengaluru India
| | - Sanjeev Jain
- Department of Psychiatry; National Institute of Mental Health and Neuro Sciences; Bengaluru India
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8
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Polyzos AA, Wood NI, Williams P, Wipf P, Morton AJ, McMurray CT. XJB-5-131-mediated improvement in physiology and behaviour of the R6/2 mouse model of Huntington's disease is age- and sex- dependent. PLoS One 2018; 13:e0194580. [PMID: 29630611 PMCID: PMC5890981 DOI: 10.1371/journal.pone.0194580] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 03/06/2018] [Indexed: 11/18/2022] Open
Abstract
We have reported that the radical scavenger XJB-5-131 attenuates or reverses progression of the disease phenotype in the HdhQ(150/150) mouse, a slow onset model of HD. Here, we tested whether XJB-5-131 has beneficial effects in R6/2 mice, a severe early onset model of HD. We found that XJB-5-131 has beneficial effects in R6/2 mice, by delaying features of the motor and histological phenotype. The impact was sex-dependent, with a stronger effect in male mice. XJB-5-131 treatment improved some locomotor deficits in female R6/2 mice, but the effects were, in general, greater in male mice. Chronic treatment of male R6/2 mice with XJB-5-1-131 reduced weight loss, and improved the motor and temperature regulation deficits, especially in male mice. Treatment with XJB-5-131 had no effect on the lifespan of R6/2 mice. Nevertheless, it significantly slowed somatic expansion at 90 days, and reduced the density of inclusions. Our data show that while treatment with XJB-5-131 had complex effects on the phenotype of R6/2 mice, it produced a number of significant improvements in this severe model of HD.
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Affiliation(s)
- Aris A. Polyzos
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
| | - Nigel I. Wood
- Department of Physiology, Development, and Neuroscience, Anatomy Building, University of Cambridge, Cambridge, United Kingdom
| | - Paul Williams
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
| | - Peter Wipf
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - A. Jennifer Morton
- Department of Physiology, Development, and Neuroscience, Anatomy Building, University of Cambridge, Cambridge, United Kingdom
| | - Cynthia T. McMurray
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
- * E-mail:
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9
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Reiner A, Deng Y. Disrupted striatal neuron inputs and outputs in Huntington's disease. CNS Neurosci Ther 2018; 24:250-280. [PMID: 29582587 PMCID: PMC5875736 DOI: 10.1111/cns.12844] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 02/15/2018] [Accepted: 02/16/2018] [Indexed: 12/22/2022] Open
Abstract
Huntington's disease (HD) is a hereditary progressive neurodegenerative disorder caused by a CAG repeat expansion in the gene coding for the protein huntingtin, resulting in a pathogenic expansion of the polyglutamine tract in the N-terminus of this protein. The HD pathology resulting from the mutation is most prominent in the striatal part of the basal ganglia, and progressive differential dysfunction and loss of striatal projection neurons and interneurons account for the progression of motor deficits seen in this disease. The present review summarizes current understanding regarding the progression in striatal neuron dysfunction and loss, based on studies both in human HD victims and in genetic mouse models of HD. We review evidence on early loss of inputs to striatum from cortex and thalamus, which may be the basis of the mild premanifest bradykinesia in HD, as well as on the subsequent loss of indirect pathway striatal projection neurons and their outputs to the external pallidal segment, which appears to be the basis of the chorea seen in early symptomatic HD. Later loss of direct pathway striatal projection neurons and their output to the internal pallidal segment account for the severe akinesia seen late in HD. Loss of parvalbuminergic striatal interneurons may contribute to the late dystonia and rigidity.
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Affiliation(s)
- Anton Reiner
- Department of Anatomy & NeurobiologyThe University of Tennessee Health Science CenterMemphisTNUSA
- Department of OphthalmologyThe University of Tennessee Health Science CenterMemphisTNUSA
| | - Yun‐Ping Deng
- Department of Anatomy & NeurobiologyThe University of Tennessee Health Science CenterMemphisTNUSA
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10
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Increased Levels of Rictor Prevent Mutant Huntingtin-Induced Neuronal Degeneration. Mol Neurobiol 2018; 55:7728-7742. [DOI: 10.1007/s12035-018-0956-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 02/06/2018] [Indexed: 01/21/2023]
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11
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Miniarikova J, Evers MM, Konstantinova P. Translation of MicroRNA-Based Huntingtin-Lowering Therapies from Preclinical Studies to the Clinic. Mol Ther 2018; 26:947-962. [PMID: 29503201 DOI: 10.1016/j.ymthe.2018.02.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 01/30/2018] [Accepted: 02/05/2018] [Indexed: 12/21/2022] Open
Abstract
The single mutation underlying the fatal neuropathology of Huntington's disease (HD) is a CAG triplet expansion in exon 1 of the huntingtin (HTT) gene, which gives rise to a toxic mutant HTT protein. There have been a number of not yet successful therapeutic advances in the treatment of HD. The current excitement in the HD field is due to the recent development of therapies targeting the culprit of HD either at the DNA or RNA level to reduce the overall mutant HTT protein. In this review, we briefly describe short-term and long-term HTT-lowering strategies targeting HTT transcripts. One of the most advanced HTT-lowering strategies is a microRNA (miRNA)-based gene therapy delivered by a single administration of an adeno-associated viral (AAV) vector to the HD patient. We outline the outcome measures for the miRNA-based HTT-lowering therapy in the context of preclinical evaluation in HD animal and cell models. We highlight the strengths and ongoing queries of the HTT-lowering gene therapy as an HD intervention with a potential disease-modifying effect. This review provides a perspective on the fast-developing HTT-lowering therapies for HD and their translation to the clinic based on existing knowledge in preclinical models.
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Affiliation(s)
- Jana Miniarikova
- Department of Research and Development, uniQure, Amsterdam, the Netherlands; Department of Gastroenterology and Hepatology, Leiden University Medical Center, Leiden, the Netherlands
| | - Melvin M Evers
- Department of Research and Development, uniQure, Amsterdam, the Netherlands
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12
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Abstract
The identification of the mutation causing Huntington's disease (HD) has led to the generation of a large number of mouse models. These models are used to further enhance our understanding of the mechanisms underlying the disease, as well as investigating and identifying therapeutic targets for this disorder. Here we review the transgenic, knock-in mice commonly used to model HD, as well those that have been generated to study specific disease mechanisms. We then provide a brief overview of the importance of standardizing the use of HD mice and describe brief protocols used for genotyping the mouse models used within the Bates Laboratory.
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Affiliation(s)
- Pamela P Farshim
- Department of Neurodegenerative Disease, Huntington's Disease Centre and Dementia Research Institute, University College London Institute of Neurology, London, WC1N 3BG, UK
| | - Gillian P Bates
- Department of Neurodegenerative Disease, Huntington's Disease Centre and Dementia Research Institute, University College London Institute of Neurology, London, WC1N 3BG, UK.
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13
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Dragatsis I, Dietrich P, Ren H, Deng YP, Del Mar N, Wang HB, Johnson IM, Jones KR, Reiner A. Effect of early embryonic deletion of huntingtin from pyramidal neurons on the development and long-term survival of neurons in cerebral cortex and striatum. Neurobiol Dis 2017; 111:102-117. [PMID: 29274742 PMCID: PMC5821111 DOI: 10.1016/j.nbd.2017.12.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 11/07/2017] [Accepted: 12/19/2017] [Indexed: 12/12/2022] Open
Abstract
We evaluated the impact of early embryonic deletion of huntingtin (htt) from pyramidal neurons on cortical development, cortical neuron survival and motor behavior, using a cre-loxP strategy to inactivate the mouse htt gene (Hdh) in emx1-expressing cell lineages. Western blot confirmed substantial htt reduction in cerebral cortex of these Emx-httKO mice, with residual cortical htt in all likelihood restricted to cortical interneurons of the subpallial lineage and/or vascular endothelial cells. Despite the loss of htt early in development, cortical lamination was normal, as revealed by layer-specific markers. Cortical volume and neuron abundance were, however, significantly less than normal, and cortical neurons showed reduced brain-derived neurotrophic factor (BDNF) expression and reduced activation of BDNF signaling pathways. Nonetheless, cortical volume and neuron abundance did not show progressive age-related decline in Emx-httKO mice out to 24 months. Although striatal neurochemistry was normal, reductions in striatal volume and neuron abundance were seen in Emx-httKO mice, which were again not progressive. Weight maintenance was normal in Emx-httKO mice, but a slight rotarod deficit and persistent hyperactivity were observed throughout the lifespan. Our results show that embryonic deletion of htt from developing pallium does not substantially alter migration of cortical neurons to their correct laminar destinations, but does yield reduced cortical and striatal size and neuron numbers. The Emx-httKO mice were persistently hyperactive, possibly due to defects in corticostriatal development. Importantly, deletion of htt from cortical pyramidal neurons did not yield age-related progressive cortical or striatal pathology.
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Affiliation(s)
- I Dragatsis
- Department of Physiology, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - P Dietrich
- Department of Physiology, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - H Ren
- Department of Anatomy & Neurobiology, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - Y P Deng
- Department of Anatomy & Neurobiology, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - N Del Mar
- Department of Anatomy & Neurobiology, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - H B Wang
- Department of Anatomy & Neurobiology, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - I M Johnson
- Department of Physiology, The University of Tennessee Health Science Center, Memphis, TN 38163, United States
| | - K R Jones
- Department of Molecular, Cellular, & Developmental Biology, 347 UCB, University of Colorado, Boulder, CO 80309, United States
| | - A Reiner
- Department of Anatomy & Neurobiology, The University of Tennessee Health Science Center, Memphis, TN 38163, United States; Department of Ophthalmology, The University of Tennessee Health Science Center, Memphis, TN 38163, United States.
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14
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Sawiak SJ, Wood NI, Morton AJ. Similar Progression of Morphological and Metabolic Phenotype in R6/2 Mice with Different CAG Repeats Revealed by In Vivo Magnetic Resonance Imaging and Spectroscopy. J Huntingtons Dis 2017; 5:271-283. [PMID: 27662335 DOI: 10.3233/jhd-160208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Huntington's disease (HD) is caused by an unstable polyglutamine (CAG) repeat in the HD gene, whereby a CAG repeat length greater than ∼36 leads to the disease. In HD patients, longer repeats correlate with more severe disease and earlier death. This is also seen in R6/2 mice carrying repeat lengths up to ∼200. Paradoxically, R6/2 mice with repeat lengths >300 have a less aggressive phenotype and longer lifespan than those with shorter repeats. The mechanism underlying this phenomenon is unknown. OBJECTIVE To investigate the consequences of longer repeat lengths on structural changes in the brains of R6/2 mice, especially with regard to progressive atrophy. METHODS We used longitudinal in vivo magnetic resonance imaging (MRI) and spectroscopy (MRS) to compare pathological changes in two strains of R6/2 mice, one with a rapidly progressing disease (250 CAG repeats), and the other with a less aggressive phenotype (350 CAG repeats). RESULTS We found significant progressive brain atrophy in both 250 and 350 CAG repeat mice, as well as changes in metabolites (glutamine/glutamate, choline and aspartate). Although similar in magnitude, atrophy in the brains of 350 CAG R6/2 mice progressed more slowly than that seen in 250 CAG mice, in line with the milder phenotype and longer lifespan. Interestingly, significant atrophy was detectable in 350 CAG mice as early as 8-12 weeks of age, although behavioural abnormalities in these mice are not apparent before 25-30 weeks. This finding fits well with human data from the PREDICT-HD and TRACK-HD project, where reductions in brain volume were found 10 years in advance of the onset of symptoms. CONCLUSIONS The similar brain atrophy with a mismatch between onset of brain atrophy and behavioural phenotype in HD mice with 350 repeats will make this mouse particularly useful for modelling early stages of HD pathology.
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Affiliation(s)
- Stephen J Sawiak
- Wolfson Brain Imaging Centre, University of Cambridge, Box 65 Addenbrooke's Hospital, Cambridge, UK.,Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - Nigel I Wood
- Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - A Jennifer Morton
- Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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15
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Jacobsen JC, Erdin S, Chiang C, Hanscom C, Handley RR, Barker DD, Stortchevoi A, Blumenthal I, Reid SJ, Snell RG, MacDonald ME, Morton AJ, Ernst C, Gusella JF, Talkowski ME. Potential molecular consequences of transgene integration: The R6/2 mouse example. Sci Rep 2017; 7:41120. [PMID: 28120936 PMCID: PMC5264158 DOI: 10.1038/srep41120] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/11/2016] [Indexed: 01/09/2023] Open
Abstract
Integration of exogenous DNA into a host genome represents an important route to generate animal and cellular models for exploration into human disease and therapeutic development. In most models, little is known concerning structural integrity of the transgene, precise site of integration, or its impact on the host genome. We previously used whole-genome and targeted sequencing approaches to reconstruct transgene structure and integration sites in models of Huntington’s disease, revealing complex structural rearrangements that can result from transgenesis. Here, we demonstrate in the R6/2 mouse, a widely used Huntington’s disease model, that integration of a rearranged transgene with coincident deletion of 5,444 bp of host genome within the gene Gm12695 has striking molecular consequences. Gm12695, the function of which is unknown, is normally expressed at negligible levels in mouse brain, but transgene integration has resulted in cortical expression of a partial fragment (exons 8–11) 3’ to the transgene integration site in R6/2. This transcript shows significant expression among the extensive network of differentially expressed genes associated with this model, including synaptic transmission, cell signalling and transcription. These data illustrate the value of sequence-level resolution of transgene insertions and transcription analysis to inform phenotypic characterization of transgenic models utilized in therapeutic research.
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Affiliation(s)
- Jessie C Jacobsen
- Centre for Brain Research, School of Biological Sciences, The University of Auckland 1010, New Zealand
| | - Serkan Erdin
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Program in Medical and Population Genetics, Broad Institute of M.I.T and Harvard, Cambridge, Massachusetts 02143, USA
| | - Colby Chiang
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Carrie Hanscom
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Renee R Handley
- Centre for Brain Research, School of Biological Sciences, The University of Auckland 1010, New Zealand
| | - Douglas D Barker
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Alex Stortchevoi
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Ian Blumenthal
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Suzanne J Reid
- Centre for Brain Research, School of Biological Sciences, The University of Auckland 1010, New Zealand
| | - Russell G Snell
- Centre for Brain Research, School of Biological Sciences, The University of Auckland 1010, New Zealand
| | - Marcy E MacDonald
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Program in Medical and Population Genetics, Broad Institute of M.I.T and Harvard, Cambridge, Massachusetts 02143, USA.,Department of Neurology, Harvard Medical School, Boston, Massachusetts 02115 USA
| | - A Jennifer Morton
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, United Kingdom
| | - Carl Ernst
- Department of Psychiatry, McGill University, Montreal, Quebec ON H4H 1R3, Canada
| | - James F Gusella
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Program in Medical and Population Genetics, Broad Institute of M.I.T and Harvard, Cambridge, Massachusetts 02143, USA.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115 USA
| | - Michael E Talkowski
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Program in Medical and Population Genetics, Broad Institute of M.I.T and Harvard, Cambridge, Massachusetts 02143, USA.,Department of Neurology, Harvard Medical School, Boston, Massachusetts 02115 USA.,Psychiatric and Neurodevelopmental Genetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, 02114 USA
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16
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Rué L, Bañez-Coronel M, Creus-Muncunill J, Giralt A, Alcalá-Vida R, Mentxaka G, Kagerbauer B, Zomeño-Abellán MT, Aranda Z, Venturi V, Pérez-Navarro E, Estivill X, Martí E. Targeting CAG repeat RNAs reduces Huntington's disease phenotype independently of huntingtin levels. J Clin Invest 2016; 126:4319-4330. [PMID: 27721240 DOI: 10.1172/jci83185] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 09/08/2016] [Indexed: 12/11/2022] Open
Abstract
Huntington's disease (HD) is a polyglutamine disorder caused by a CAG expansion in the Huntingtin (HTT) gene exon 1. This expansion encodes a mutant protein whose abnormal function is traditionally associated with HD pathogenesis; however, recent evidence has also linked HD pathogenesis to RNA stable hairpins formed by the mutant HTT expansion. Here, we have shown that a locked nucleic acid-modified antisense oligonucleotide complementary to the CAG repeat (LNA-CTG) preferentially binds to mutant HTT without affecting HTT mRNA or protein levels. LNA-CTGs produced rapid and sustained improvement of motor deficits in an R6/2 mouse HD model that was paralleled by persistent binding of LNA-CTG to the expanded HTT exon 1 transgene. Motor improvement was accompanied by a pronounced recovery in the levels of several striatal neuronal markers severely impaired in R6/2 mice. Furthermore, in R6/2 mice, LNA-CTG blocked several pathogenic mechanisms caused by expanded CAG RNA, including small RNA toxicity and decreased Rn45s expression levels. These results suggest that LNA-CTGs promote neuroprotection by blocking the detrimental activity of CAG repeats within HTT mRNA. The present data emphasize the relevance of expanded CAG RNA to HD pathogenesis, indicate that inhibition of HTT expression is not required to reverse motor deficits, and further suggest a therapeutic potential for LNA-CTG in polyglutamine disorders.
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17
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Large-scale phenome analysis defines a behavioral signature for Huntington's disease genotype in mice. Nat Biotechnol 2016; 34:838-44. [PMID: 27376585 DOI: 10.1038/nbt.3587] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/28/2016] [Indexed: 12/20/2022]
Abstract
Rapid technological advances for the frequent monitoring of health parameters have raised the intriguing possibility that an individual's genotype could be predicted from phenotypic data alone. Here we used a machine learning approach to analyze the phenotypic effects of polymorphic mutations in a mouse model of Huntington's disease that determine disease presentation and age of onset. The resulting model correlated variation across 3,086 behavioral traits with seven different CAG-repeat lengths in the huntingtin gene (Htt). We selected behavioral signatures for age and CAG-repeat length that most robustly distinguished between mouse lines and validated the model by correctly predicting the repeat length of a blinded mouse line. Sufficient discriminatory power to accurately predict genotype required combined analysis of >200 phenotypic features. Our results suggest that autosomal dominant disease-causing mutations could be predicted through the use of subtle behavioral signatures that emerge in large-scale, combinatorial analyses. Our work provides an open data platform that we now share with the research community to aid efforts focused on understanding the pathways that link behavioral consequences to genetic variation in Huntington's disease.
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18
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Glynn D, Skillings EA, Morton AJ. A comparison of discrimination learning in touchscreen and 2-choice swim tank using an allelic series of Huntington's disease mice. J Neurosci Methods 2016. [DOI: 10.1016/j.jneumeth.2015.07.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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19
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Kumar A, Zhang J, Tallaksen-Greene S, Crowley MR, Crossman DK, Morton AJ, Van Groen T, Kadish I, Albin RL, Lesort M, Detloff PJ. Allelic series of Huntington's disease knock-in mice reveals expression discorrelates. Hum Mol Genet 2016; 25:1619-36. [PMID: 26908599 DOI: 10.1093/hmg/ddw040] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 02/08/2016] [Indexed: 11/13/2022] Open
Abstract
Identifying molecular drivers of pathology provides potential therapeutic targets. Differentiating between drivers and coincidental molecular alterations presents a major challenge. Variation unrelated to pathology further complicates transcriptomic, proteomic and metabolomic studies which measure large numbers of individual molecules. To overcome these challenges towards the goal of determining drivers of Huntington's disease (HD), we generated an allelic series of HD knock-in mice with graded levels of phenotypic severity for comparison with molecular alterations. RNA-sequencing analysis of this series reveals high numbers of transcripts with level alterations that do not correlate with phenotypic severity. These discorrelated molecular changes are unlikely to be drivers of pathology allowing an exclusion-based strategy to provide a short list of driver candidates. Further analysis of the data shows that a majority of transcript level changes in HD knock-in mice involve alteration of the rate of mRNA processing and/or degradation rather than solely being due to alteration of transcription rate. The overall strategy described can be applied to assess the influence of any molecular change on pathology for diseases where different mutations cause graded phenotypic severity.
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Affiliation(s)
- Ashish Kumar
- Department of Cell, Developmental and Integrative Biology
| | | | - Sara Tallaksen-Greene
- VAAAHS GRECC, Ann Arbor, MI, USA and Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | | | - A Jennifer Morton
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | | | - Inga Kadish
- Department of Cell, Developmental and Integrative Biology
| | - Roger L Albin
- VAAAHS GRECC, Ann Arbor, MI, USA and Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Mathieu Lesort
- Department of Psychiatry, University of Alabama at Birmingham, Birmingham, AL, USA
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20
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Kantor S, Varga J, Morton AJ. A single dose of hypnotic corrects sleep and EEG abnormalities in symptomatic Huntington's disease mice. Neuropharmacology 2016; 105:298-307. [PMID: 26805423 DOI: 10.1016/j.neuropharm.2016.01.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 12/23/2015] [Accepted: 01/20/2016] [Indexed: 11/24/2022]
Abstract
Sleep and electroencephalogram abnormalities are prominent early features of Huntington's disease (HD) that typically appear before the onset of characteristic motor symptoms. The changes in sleep and electroencephalogram seen in HD patients are largely recapitulated in mouse models of HD such as transgenic R6/2 lines. To test whether or not drugs with hypnotic properties can correct the sleep and electroencephalogram abnormalities seen in HD mice, we treated male wild-type (WT; N = 7) and R6/2 mice (N = 9) acutely with intraperitoneal injections of vehicle, zolpidem (5, 10 or 20 mg/kg) or amitriptyline (5, 10 or 20 mg/kg), and then monitored their sleep-wake behavior. In R6/2 mice, both zolpidem and amitriptyline suppressed the abnormally high REM sleep amount and electroencephalographic gamma (30-46 Hz) oscillations in a dose-dependent manner. Amitriptyline's effect on sleep was similar in both genotypes, whereas zolpidem showed significant genotype differences. Zolpidem exerted a strong hypnotic effect in WT mice by increasing electroencephalographic delta power, doubling the mean bout duration and the total amount of non-rapid eye movement sleep. However, no such effect was seen in R6/2 mice. Our study demonstrates that the pathophysiological changes seen in sleep and electroencephalogram are not 'hard-wired' in HD brain and can be reversed even at late stages of the disease. The diminished hypnotic effect of zolpidem suggests that the GABAergic control of sleep-wake states is impaired in HD mice. A better understanding of the neurochemical basis underlying these abnormalities should lead to more effective and rational therapies for HD.
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Affiliation(s)
- Sandor Kantor
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom
| | - Janos Varga
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom
| | - A Jennifer Morton
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom.
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21
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Sawiak SJ, Morton AJ. The Cambridge MRI database for animal models of Huntington disease. Neuroimage 2016; 124:1260-1262. [PMID: 25941090 DOI: 10.1016/j.neuroimage.2015.04.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/23/2015] [Accepted: 04/26/2015] [Indexed: 12/11/2022] Open
Abstract
We describe the Cambridge animal brain magnetic resonance imaging repository comprising 400 datasets to date from mouse models of Huntington disease. The data include raw images as well as segmented grey and white matter images with maps of cortical thickness. All images and phenotypic data for each subject are freely-available without restriction from (http://www.dspace.cam.ac.uk/handle/1810/243361/). Software and anatomical population templates optimised for animal brain analysis with MRI are also available from this site.
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Affiliation(s)
- Stephen J Sawiak
- Wolfson Brain Imaging Centre, University of Cambridge, Box 65 Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK; Behavioural and Clinical Neuroscience Institute, University of Cambridge, Downing Street, Cambridge, UK; Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, UK.
| | - A Jennifer Morton
- Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, UK
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22
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Age-, tissue- and length-dependent bidirectional somatic CAG•CTG repeat instability in an allelic series of R6/2 Huntington disease mice. Neurobiol Dis 2015; 76:98-111. [PMID: 25662336 DOI: 10.1016/j.nbd.2015.01.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 11/30/2014] [Accepted: 01/25/2015] [Indexed: 12/11/2022] Open
Abstract
The expansion of simple sequence CAG•CTG repeats is associated with a number of inherited disorders including Huntington disease (HD), myotonic dystrophy type 1 and several of the spinocerebellar ataxias. Inherited disease-associated alleles usually exceed 40 repeats and may be in excess of 1,000 repeats in some disorders. Inherited allele length is inversely proportional to age at onset, and frequent germline expansions account for the striking anticipation observed in affected families. Expanded disease associated alleles are also somatically unstable via a pathway that is age dependent and tissue specific, and also appears to be expansion biased. Somatic expansions are thought to contribute toward both tissue specificity and disease progression. Here we have examined the somatic mutational dynamics in brain and peripheral tissues from an allelic series of R6/2 HD transgenic mice inheriting from 52 to >700 CAG repeats. We found age-dependent, tissue-specific somatic instability, with particularly large expansions observed in the striatum and cortex. We also found a positive increase in somatic instability with increasing allele length. Surprisingly, however, the degree of somatic variation did not increase in a linear fashion, but leveled off with increasing allele length. Most unexpectedly, the almost exclusive bias toward the accumulation of expansions observed in mice inheriting smaller alleles was lost, and a high frequency of large somatic contractions was observed in mice inheriting very large alleles (>500 repeats). These data highlight the bidirectional nature of CAG•CTG repeat instability and the subtle balance that exists between expansion and contraction in vivo. Defining the dynamics and tissue specificity of expansion and contraction is important for understanding the role of genetic instability in pathophysiology and in particular the development of novel therapies based on suppressing expansions and/or promoting contractions.
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23
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Hoffner G, Djian P. Polyglutamine Aggregation in Huntington Disease: Does Structure Determine Toxicity? Mol Neurobiol 2014; 52:1297-1314. [PMID: 25336039 DOI: 10.1007/s12035-014-8932-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 10/09/2014] [Indexed: 01/14/2023]
Abstract
Huntington disease is a dominantly inherited disease of the central nervous system. The mutational expansion of polyglutamine beyond a critical length produces a toxic gain of function in huntingtin and results in neuronal death. In the course of the disease, expanded huntingtin is proteolyzed, becomes abnormally folded, and accumulates in oligomers, fibrils, and microscopic inclusions. The aggregated forms of the expanded protein are structurally diverse. Structural heterogeneity may explain why polyglutamine-containing aggregates could paradoxically be either toxic or neuroprotective. When defined, the toxic structures could then specifically be targeted by prophylactic or therapeutic drugs aimed at inhibiting polyglutamine aggregation.
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Affiliation(s)
- Guylaine Hoffner
- Laboratoire de Physiologie Cérébrale, Centre National de la Recherche Scientifique, Université Paris Descartes, 45 rue des Saints Pères, 75006, Paris, France
| | - Philippe Djian
- Laboratoire de Physiologie Cérébrale, Centre National de la Recherche Scientifique, Université Paris Descartes, 45 rue des Saints Pères, 75006, Paris, France.
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24
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Aronin N, DiFiglia M. Huntingtin-lowering strategies in Huntington's disease: antisense oligonucleotides, small RNAs, and gene editing. Mov Disord 2014; 29:1455-61. [PMID: 25164989 DOI: 10.1002/mds.26020] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 08/12/2014] [Accepted: 08/15/2014] [Indexed: 12/21/2022] Open
Abstract
The idea to lower mutant huntingtin is especially appealing in Huntington's disease (HD). It is autosomal dominant, so that expression of the mutant allele causes the disease. Advances in RNA and gene regulation provide foundations for the huntingtin gene (both normal and mutant alleles) and possibly the mutant allele only. There is much preclinical animal work to support the concept of gene and RNA silencing, but, to date, no clinical studies have been attempted in HD. Preventing expression of mutant huntingtin protein is at the cusp for a human trial. Antisense oligonucleotides delivered to patients with amyotrophic lateral sclerosis have been well tolerated; small RNAs administered to rodent and nonhuman primate brain knocked down huntingtin messenger RNA (mRNA); short-hairpin complementary DNA of microRNAs can be expressed in adeno-associated virus to provide long-term silencing of huntingtin mRNA and protein. We expect that these approaches will be ready for clinical studies in the near future, once safety has been validated. Our understanding of gene editing-changing the huntingtin gene itself-is rapidly progressing. Harnessing our knowledge of transcription and translation should push scientific creativity to new and exciting advances that overcome the lethality of the mutant gene in HD.
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Affiliation(s)
- Neil Aronin
- Department of Medicine and RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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25
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Menalled LB, Kudwa AE, Oakeshott S, Farrar A, Paterson N, Filippov I, Miller S, Kwan M, Olsen M, Beltran J, Torello J, Fitzpatrick J, Mushlin R, Cox K, McConnell K, Mazzella M, He D, Osborne GF, Al-Nackkash R, Bates GP, Tuunanen P, Lehtimaki K, Brunner D, Ghavami A, Ramboz S, Park L, Macdonald D, Munoz-Sanjuan I, Howland D. Genetic deletion of transglutaminase 2 does not rescue the phenotypic deficits observed in R6/2 and zQ175 mouse models of Huntington's disease. PLoS One 2014; 9:e99520. [PMID: 24955833 PMCID: PMC4067284 DOI: 10.1371/journal.pone.0099520] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 05/13/2014] [Indexed: 11/18/2022] Open
Abstract
Huntington's disease (HD) is an autosomal dominant, progressive neurodegenerative disorder caused by expansion of CAG repeats in the huntingtin gene. Tissue transglutaminase 2 (TG2), a multi-functional enzyme, was found to be increased both in HD patients and in mouse models of the disease. Furthermore, beneficial effects have been reported from the genetic ablation of TG2 in R6/2 and R6/1 mouse lines. To further evaluate the validity of this target for the treatment of HD, we examined the effects of TG2 deletion in two genetic mouse models of HD: R6/2 CAG 240 and zQ175 knock in (KI). Contrary to previous reports, under rigorous experimental conditions we found that TG2 ablation had no effect on either motor or cognitive deficits, or on the weight loss. In addition, under optimal husbandry conditions, TG2 ablation did not extend R6/2 lifespan. Moreover, TG2 deletion did not change the huntingtin aggregate load in cortex or striatum and did not decrease the brain atrophy observed in either mouse line. Finally, no amelioration of the dysregulation of striatal and cortical gene markers was detected. We conclude that TG2 is not a valid therapeutic target for the treatment of HD.
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Affiliation(s)
| | - Andrea E. Kudwa
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Steve Oakeshott
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Andrew Farrar
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Neil Paterson
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Igor Filippov
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Sam Miller
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Mei Kwan
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Michael Olsen
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Jose Beltran
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Justin Torello
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Jon Fitzpatrick
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Richard Mushlin
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Kimberly Cox
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Kristi McConnell
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Matthew Mazzella
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Dansha He
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Georgina F. Osborne
- Department of Medical and Molecular Genetics, King's College London, London, United Kingdom
| | - Rand Al-Nackkash
- Department of Medical and Molecular Genetics, King's College London, London, United Kingdom
| | - Gill P. Bates
- Department of Medical and Molecular Genetics, King's College London, London, United Kingdom
| | - Pasi Tuunanen
- Charles River Discovery Research Services, Kuopio, Finland
| | | | - Dani Brunner
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Afshin Ghavami
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Sylvie Ramboz
- PsychoGenics Inc., Tarrytown, New York, United States of America
| | - Larry Park
- CHDI Management/CHDI Foundation, Princeton, New Jersey, United States of America
| | - Douglas Macdonald
- CHDI Management/CHDI Foundation, Princeton, New Jersey, United States of America
| | | | - David Howland
- CHDI Management/CHDI Foundation, Princeton, New Jersey, United States of America
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26
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Landrum E, Wetzel R. Biophysical underpinnings of the repeat length dependence of polyglutamine amyloid formation. J Biol Chem 2014; 289:10254-10260. [PMID: 24596088 DOI: 10.1074/jbc.c114.552943] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
There are now 10 expanded CAG repeat diseases in which both disease risk and age of onset are strongly dependent on the repeat length of the polyglutamine (polyQ) sequence in the disease protein. Large, polyQ-rich inclusions in patient brains and in cell and animal models are consistent with the involvement of polyQ aggregation in the disease mechanism. This possibility is reinforced by studies showing strong repeat length dependence to the aggregation process, qualitatively mirroring the repeat length dependence of disease risk. Our understanding of the underlying biophysical principles that mediate the repeat length dependence of aggregation, however, is far from complete. A previous study of simple polyQ peptides showed that N*, the size of the critical nucleus that controls onset of aggregation, decreases from unfavorable tetramer to favorable monomer over the range Q23 to Q26. These data, however, do not explain why, for all peptides exhibiting N* ∼ 1, spontaneous aggregation rates continue to increase with increasing repeat length. Here we describe a novel kinetics analyses that maps out the nonlinear dependence with repeat length of a nucleation efficiency term that is likely related to aspects of nucleus structure. This trend accounts for why nucleus size increases to tetrameric at repeat lengths of Q23 or below. Intriguingly, both aggregation and age of onset trend with repeat length in similar ways, exhibiting large changes per added Gln at low repeat lengths and small changes per added Gln at relatively long repeat lengths. Fibril stability also increases with repeat length in a nonlinear fashion.
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Affiliation(s)
- Elizabeth Landrum
- Department of Structural Biology and the Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260
| | - Ronald Wetzel
- Department of Structural Biology and the Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260.
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27
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Heldt SA, Elberger AJ, Deng Y, Guley NH, Del Mar N, Rogers J, Choi GW, Ferrell J, Rex TS, Honig MG, Reiner A. A novel closed-head model of mild traumatic brain injury caused by primary overpressure blast to the cranium produces sustained emotional deficits in mice. Front Neurol 2014; 5:2. [PMID: 24478749 PMCID: PMC3898331 DOI: 10.3389/fneur.2014.00002] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 01/06/2014] [Indexed: 12/14/2022] Open
Abstract
Emotional disorders are a common outcome from mild traumatic brain injury (TBI) in humans, but their pathophysiological basis is poorly understood. We have developed a mouse model of closed-head blast injury using an air pressure wave delivered to a small area on one side of the cranium, to create mild TBI. We found that 20-psi blasts in 3-month-old C57BL/6 male mice yielded no obvious behavioral or histological evidence of brain injury, while 25-40 psi blasts produced transient anxiety in an open field arena but little histological evidence of brain damage. By contrast, 50-60 psi blasts resulted in anxiety-like behavior in an open field arena that became more evident with time after blast. In additional behavioral tests conducted 2-8 weeks after blast, 50-60 psi mice also demonstrated increased acoustic startle, perseverance of learned fear, and enhanced contextual fear, as well as depression-like behavior and diminished prepulse inhibition. We found no evident cerebral pathology, but did observe scattered axonal degeneration in brain sections from 50 to 60 psi mice 3-8 weeks after blast. Thus, the TBI caused by single 50-60 psi blasts in mice exhibits the minimal neuronal loss coupled to "diffuse" axonal injury characteristic of human mild TBI. A reduction in the abundance of a subpopulation of excitatory projection neurons in basolateral amygdala enriched in Thy1 was, however, observed. The reported link of this neuronal population to fear suppression suggests their damage by mild TBI may contribute to the heightened anxiety and fearfulness observed after blast in our mice. Our overpressure air blast model of concussion in mice will enable further studies of the mechanisms underlying the diverse emotional deficits seen after mild TBI.
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Affiliation(s)
- Scott A. Heldt
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Andrea J. Elberger
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Yunping Deng
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Natalie H. Guley
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Nobel Del Mar
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Joshua Rogers
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Gy Won Choi
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jessica Ferrell
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Tonia S. Rex
- Department of Ophthalmology, The University of Tennessee Health Science Center, Memphis, TN, USA
- Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, TN, USA
| | - Marcia G. Honig
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Anton Reiner
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
- Department of Ophthalmology, The University of Tennessee Health Science Center, Memphis, TN, USA
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Abstract
Changes in the level and activity of brain-derived neurotrophic factor (BDNF) have been described in a number of neurodegenerative disorders since early 1990s. However, only in Huntington disease (HD) gain- and loss-of-function experiments have mechanistically linked these abnormalities with the genetic defect.In this chapter we will describe how huntingtin protein, whose mutation causes HD, is involved in the physiological control of BDNF synthesis and transport in neurons and how both processes are simultaneously disrupted in HD. We will describe the underlying molecular mechanisms and discuss pre-clinical data concerning the impact of the experimental manipulation of BDNF levels on HD progression. These studies have revealed that a major loss of BDNF protein in the brain of HD patients may contribute to the clinical manifestations of the disease. The experimental strategies under investigation to increase brain BDNF levels in animal models of HD will also be described, with a view to ultimately improving the clinical treatment of this condition.
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Affiliation(s)
- Chiara Zuccato
- Department of Biosciences and Centre for Stem cell Research, Università degli Studi di Milano, Via Viotti 3/5, 20133, Milan, Italy,
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30
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Todd TW, Lim J. Aggregation formation in the polyglutamine diseases: protection at a cost? Mol Cells 2013; 36:185-94. [PMID: 23794019 PMCID: PMC3800151 DOI: 10.1007/s10059-013-0167-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 06/02/2013] [Indexed: 12/30/2022] Open
Abstract
Mutant protein aggregation is a hallmark of many neurodegenerative diseases, including the polyglutamine disorders. Although the correlation between aggregation formation and disease pathology originally suggested that the visible inclusions seen in patient tissue might directly contribute to pathology, additional studies failed to confirm this hypothesis. Current opinion in the field of polyglutamine disease research now favors a model in which large inclusions are cytoprotective and smaller oligomers or misfolded monomers underlie pathogenesis. Nonetheless, therapies aimed at reducing or preventing aggregation show promise. This review outlines the debate about the role of aggregation in the polyglutamine diseases as it has unfolded in the literature and concludes with a brief discussion on the manipulation of aggregation formation and clearance mechanisms as a means of therapeutic intervention.
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Affiliation(s)
- Tiffany W. Todd
- Department of Genetics, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Janghoo Lim
- Department of Genetics, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510, USA
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31
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Rué L, Alcalá-Vida R, López-Soop G, Creus-Muncunill J, Alberch J, Pérez-Navarro E. Early down-regulation of PKCδ as a pro-survival mechanism in Huntington's disease. Neuromolecular Med 2013; 16:25-37. [PMID: 23896721 DOI: 10.1007/s12017-013-8248-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Accepted: 07/12/2013] [Indexed: 11/29/2022]
Abstract
A balance between cell survival and apoptosis is crucial to avoid neurodegeneration. Here, we analyzed whether the pro-apoptotic protein PKCδ, and the pro-survival PKCα and βII, were dysregulated in the brain of R6/1 mouse model of Huntington's disease (HD). Protein levels of the three PKCs examined were reduced in all the brain regions analyzed being PKCδ the most affected isoform. Interestingly, PKCδ protein levels were also decreased in the striatum and cortex of R6/2 and Hdh(Q111/Q111) mice, and in the putamen of HD patients. Nuclear PKCδ induces apoptosis, but we detected reduced PKCδ in both cytoplasmic and nuclear enriched fractions from R6/1 mouse striatum, cortex and hippocampus. In addition, we show that phosphorylation and ubiquitination of PKCδ are increased in 30-week-old R6/1 mouse brain. All together these results suggest a pro-survival role of reduced PKCδ levels in response to mutant huntingtin-induced toxicity. In fact, we show that over-expression of PKCδ increases mutant huntingtin-induced cell death in vitro, whereas over-expression of a PKCδ dominant negative form or silencing of endogenous PKCδ partially blocks mutant huntingtin-induced cell death. Finally, we show that the analysis of lamin B protein levels could be a good marker of PKCδ activity, but it is not involved in PKCδ-mediated cell death in mutant huntingtin-expressing cells. In conclusion, our results suggest that neurons increase the degradation of PKCδ as a compensatory pro-survival mechanism in response to mutant huntingtin-induced toxicity that can help to understand why cell death appears late in the disease.
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Affiliation(s)
- Laura Rué
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, Casanova 143, Barcelona, 08036, Spain
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Desmond CR, Maiuri T, Truant R. A multifunctional, multi-pathway intracellular localization signal in Huntingtin. Commun Integr Biol 2013; 6:e23318. [PMID: 23750301 PMCID: PMC3609847 DOI: 10.4161/cib.23318] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Nuclear accumulation of the polyglutamine-expanded mutant huntingtin protein remains one of the most predictive cell biological phenotypes of Huntington's disease (HD) progression in patient brain samples and mouse models of the disease. Yet, the relationship between huntingtin nuclear import, neuronal dysfunction and toxicity is not fully understood and it remains unclear whether nuclear accumulation is required for disease onset. Here, we discuss several studies that have guided current understanding of this subject, and highlight our recent data detailing the discovery of a karyopherin β1/β2-type nuclear localization signal near the N-terminus of huntingtin. This signal can function through multiple pathways of nuclear import, and may also be responsible for huntingtin import into the primary cilium. This work represents a significant step forward in our knowledge of the regulatory pathways that govern huntingtin nuclear accumulation and will allow direct examination of both normal and mutant huntingtin nuclear function. This work also suggests a re-examination of the cell biology of any protein that contains a multi-pathway nuclear localization signal. The possibility of targeting huntingtin nuclear import therapeutically and the potential impacts of such a strategy for the treatment of HD are also discussed.
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Affiliation(s)
- Carly R Desmond
- Department of Biochemistry and Biomedical Sciences; McMaster University; Hamilton, ON Canada
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Rué L, López-Soop G, Gelpi E, Martínez-Vicente M, Alberch J, Pérez-Navarro E. Brain region- and age-dependent dysregulation of p62 and NBR1 in a mouse model of Huntington's disease. Neurobiol Dis 2013; 52:219-28. [PMID: 23295856 DOI: 10.1016/j.nbd.2012.12.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 11/12/2012] [Accepted: 12/21/2012] [Indexed: 10/27/2022] Open
Abstract
Huntington's disease is characterized by the formation of protein aggregates, which can be degraded by macroautophagy. Here, we studied protein levels and intracellular distribution of p62 and NBR1, two macroautophagy cargo receptors, during disease progression. In R6/1 mice, p62 and NBR1 protein levels were decreased in all brain regions analyzed early in the disease, whereas at late stages they accumulated in the striatum and hippocampus, but not in the cortex. The accumulation of p62, but not NBR1, occurred in neuronal nuclei, where it co-localized with mutant huntingtin inclusions, both in R6/1 and Huntington's disease patients. Moreover, exportin-1 was selectively decreased in old R6/1 mice brain, and could worsen p62 nuclear accumulation. In conclusion, p62 interacts with mutant huntingtin and is retained in the nucleus along the progression of the disease, mostly in striatal and hippocampal neurons. Thus, cytoplasmic NBR1 might be important to maintain basal levels of selective macroautophagy in these neurons.
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Affiliation(s)
- Laura Rué
- Departament de Biologia Cel·lular, Immunologia i Neurociències, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
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Ma L, Chen K, Clarke DJ, Nortcliffe CP, Wilson GG, Edwardson JM, Morton AJ, Jones AC, Dryden DTF. Restriction endonuclease TseI cleaves A:A and T:T mismatches in CAG and CTG repeats. Nucleic Acids Res 2013; 41:4999-5009. [PMID: 23525471 PMCID: PMC3643589 DOI: 10.1093/nar/gkt176] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The type II restriction endonuclease TseI recognizes the DNA target sequence 5′-G^CWGC-3′ (where W = A or T) and cleaves after the first G to produce fragments with three-base 5′-overhangs. We have determined that it is a dimeric protein capable of cleaving not only its target sequence but also one containing A:A or T:T mismatches at the central base pair in the target sequence. The cleavage of targets containing these mismatches is as efficient as cleavage of the correct target sequence containing a central A:T base pair. The cleavage mechanism does not apparently use a base flipping mechanism as found for some other type II restriction endonuclease recognizing similarly degenerate target sequences. The ability of TseI to cleave targets with mismatches means that it can cleave the unusual DNA hairpin structures containing A:A or T:T mismatches formed by the repetitive DNA sequences associated with Huntington’s disease (CAG repeats) and myotonic dystrophy type 1 (CTG repeats).
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Affiliation(s)
- Long Ma
- EaStChem School of Chemistry, University of Edinburgh, The King's Buildings, Edinburgh EH9 3JJ, UK
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35
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Chen JY, Wang E, Galvan L, Huynh M, Joshi P, Cepeda C, Levine MS. Effects of the Pimelic Diphenylamide Histone Deacetylase Inhibitor HDACi 4b on the R6/2 and N171-82Q Mouse Models of Huntington's Disease. PLOS CURRENTS 2013; 5. [PMID: 23437422 PMCID: PMC3574864 DOI: 10.1371/currents.hd.ec3547da1c2a520ba959ee7bf8bdd202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This report represents a detailed description of experiments designed to replicate and extend the findings of a published study on the effects of treating the R6/2 Huntington’s disease (HD) mouse model with ~300 CAG repeats using the pimelic diphenylamide histone deacetylase (HDAC) inhibitor, HDACi 4b (Thomas et al., 2008). In addition to testing the R6/2 mice, similar experiments examined the effects of the drug on a second transgenic HD mouse model, the N171-82Q mice. As in the original study, the drug was delivered in the drinking water. In the present study we tested larger groups of mice than in the original study. The results indicated that we were unable to replicate the significant behavioral effects of oral HDACi 4b treatment in the R6/2 mice. There were however, non-significant trends for the treated R6/2 mice to be less affected on some of the measures and there were instances of phenotype progression being delayed in these treated mice. In contrast, we did replicate the protection from striatal atrophy in the R6/2 mice. We also did not observe any beneficial effects of HDACi 4b treatment in the N171-82Q mice. Although the behavioral procedures were replicated and an automated activity assessment was added, there were several unexpected complications in terms of solubility of the drug, CAG repeat length differences and gender differences in progression of the phenotype that could have affected outcomes. Clearly more studies will have to be performed using other methods of delivery as well as assessing effects in more slowly progressing HD models to better evaluate the effects of this HDAC inhibitor.
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Affiliation(s)
- Jane Y Chen
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, Brain Research Institute, The David Geffen School of Medicine, University of California, Los Angeles, California
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36
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Godinho BMDC, Ogier JR, Darcy R, O’Driscoll CM, Cryan JF. Self-assembling Modified β-Cyclodextrin Nanoparticles as Neuronal siRNA Delivery Vectors: Focus on Huntington’s Disease. Mol Pharm 2013; 10:640-9. [DOI: 10.1021/mp3003946] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Bruno M. D. C. Godinho
- Pharmacodelivery Group, School
of Pharmacy, University College Cork, Cork,
Ireland
- Department of Anatomy
and Neuroscience, University College Cork, Cork, Ireland
| | - Julien R. Ogier
- Centre for
Synthesis and Chemical
Biology, University College Dublin, Dublin,
Ireland
| | - Raphael Darcy
- Centre for
Synthesis and Chemical
Biology, University College Dublin, Dublin,
Ireland
| | | | - John F. Cryan
- Department of Anatomy
and Neuroscience, University College Cork, Cork, Ireland
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, Cork, Ireland
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37
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Krauss S, Griesche N, Jastrzebska E, Chen C, Rutschow D, Achmüller C, Dorn S, Boesch SM, Lalowski M, Wanker E, Schneider R, Schweiger S. Translation of HTT mRNA with expanded CAG repeats is regulated by the MID1-PP2A protein complex. Nat Commun 2013; 4:1511. [PMID: 23443539 DOI: 10.1038/ncomms2514] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 01/18/2013] [Indexed: 11/08/2022] Open
Abstract
Expansion of CAG repeats is a common feature of various neurodegenerative disorders, including Huntington's disease. Here we show that expanded CAG repeats bind to a translation regulatory protein complex containing MID1, protein phosphatase 2A and 40S ribosomal S6 kinase. Binding of the MID1-protein phosphatase 2A protein complex increases with CAG repeat size and stimulates translation of the CAG repeat expansion containing messenger RNA in a MID1-, protein phosphatase 2A- and mammalian target of rapamycin-dependent manner. Our data indicate that pathological CAG repeat expansions upregulate protein translation leading to an overproduction of aberrant protein and suggest that the MID1-complex may serve as a therapeutic target for the treatment of CAG repeat expansion disorders.
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Affiliation(s)
- Sybille Krauss
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 25, 53127 Bonn, Germany.
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38
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Sawiak SJ, Wood NI, Carpenter TA, Morton AJ. Huntington's disease mouse models online: high-resolution MRI images with stereotaxic templates for computational neuroanatomy. PLoS One 2012; 7:e53361. [PMID: 23300918 PMCID: PMC3534048 DOI: 10.1371/journal.pone.0053361] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 11/30/2012] [Indexed: 12/14/2022] Open
Abstract
Magnetic resonance imaging (MRI) has proved to be an ideal modality for non-destructive and highly detailed assessment of structural morphology in biological tissues. Here we used MRI to make a dataset of ex vivo brains from two different rodent models of Huntington’s disease (HD), the R6/2 line and the YAC 128 mouse. We are making the whole dataset (399 transgenic HD and wildtype (WT) brains, from mice aged 9–80 weeks) publicly available. These data will be useful, not only to investigators interested in the study of HD, but also to researchers of computational neuroanatomy who may not have access to such large datasets from mouse models. Here we demonstrate a number of uses of such data, for example to produce maps of grey and white matter and cortical thickness. As an example of how the library might provide insights in mouse models of HD, we calculated whole brain grey matter volumes across different age groups with different numbers of cytosine-adenine-guanine (CAG) repeats in a fragment of the gene responsible for HD in humans. (The R6/2 dataset was obtained from an allelic series of R6/2 mice carrying a range of CAG repeat lengths between 109 and 464.) This analysis revealed different trajectories for each fragment length. In particular there was a gradient of decreasing pathology with longer CAG repeat lengths, reflecting our previous findings with behavioural and histological studies. There will be no constraints placed on the use of the datasets included here. The original data will be easily and permanently accessible via the University of Cambridge data repository (http://www.dspace.cam.ac.uk/handle/1810/243361).
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Affiliation(s)
- Stephen J Sawiak
- Wolfson Brain Imaging Centre, Department of Clinical Neuroscience, University of Cambridge, Cambridge, United Kingdom.
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39
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Conforti P, Camnasio S, Mutti C, Valenza M, Thompson M, Fossale E, Zeitlin S, MacDonald ME, Zuccato C, Cattaneo E. Lack of huntingtin promotes neural stem cells differentiation into glial cells while neurons expressing huntingtin with expanded polyglutamine tracts undergo cell death. Neurobiol Dis 2012; 50:160-70. [PMID: 23089356 DOI: 10.1016/j.nbd.2012.10.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/10/2012] [Accepted: 10/13/2012] [Indexed: 10/27/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder that affects muscle coordination and diminishes cognitive abilities. The genetic basis of the disease is an expansion of CAG repeats in the Huntingtin (Htt) gene. Here we aimed to generate a series of mouse neural stem (NS) cell lines that carried varying numbers of CAG repeats in the mouse Htt gene (Hdh CAG knock-in NS cells) or that had Hdh null alleles (Hdh knock-out NS cells). Towards this end, Hdh CAG knock-in mouse ES cell lines that carried an Htt gene with 20, 50, 111, or 140 CAG repeats or that were Htt null were neuralized and converted into self-renewing NS cells. The resulting NS cell lines were immunopositive for the neural stem cell markers NESTIN, SOX2, and BLBP and had similar proliferative rates and cell cycle distributions. After 14 days in vitro, wild-type NS cells gave rise to cultures composed of 70% MAP2(+) neurons and 30% GFAP(+) astrocytes. In contrast, NS cells with expanded CAG repeats underwent neuronal cell death, with only 38%±15% of the MAP2(+) cells remaining at the end of the differentiation period. Cell death was verified by increased caspase 3/7 activity on day 14 of the neuronal differentiation protocol. Interestingly, Hdh knock-out NS cells treated using the same neuronal differentiation protocol showed a dramatic increase in the number of GFAP(+) cells on day 14 (61%±20% versus 24%±10% in controls), and a massive decrease of MAP2(+) neurons (30%±11% versus 64%±17% in controls). Both Hdh CAG knock-in NS cells and Hdh knock-out NS cells showed reduced levels of Bdnf mRNA during neuronal differentiation, in agreement with data obtained previously in HD mouse models and in post-mortem brain samples from HD patients. We concluded that Hdh CAG knock-in and Hdh knock-out NS cells have potential as tools for investigating the roles of normal and mutant HTT in differentiated neurons and glial cells of the brain.
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Affiliation(s)
- Paola Conforti
- Center for Stem Cell Research, Università degli Studi di Milano, Via Balzaretti 9, 20113 Milan, Italy
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40
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Figiel M, Szlachcic WJ, Switonski PM, Gabka A, Krzyzosiak WJ. Mouse models of polyglutamine diseases: review and data table. Part I. Mol Neurobiol 2012; 46:393-429. [PMID: 22956270 PMCID: PMC3461215 DOI: 10.1007/s12035-012-8315-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2012] [Accepted: 07/29/2012] [Indexed: 12/23/2022]
Abstract
Polyglutamine (polyQ) disorders share many similarities, such as a common mutation type in unrelated human causative genes, neurological character, and certain aspects of pathogenesis, including morphological and physiological neuronal alterations. The similarities in pathogenesis have been confirmed by findings that some experimental in vivo therapy approaches are effective in multiple models of polyQ disorders. Additionally, mouse models of polyQ diseases are often highly similar between diseases with respect to behavior and the features of the disease. The common features shared by polyQ mouse models may facilitate the investigation of polyQ disorders and may help researchers explore the mechanisms of these diseases in a broader context. To provide this context and to promote the understanding of polyQ disorders, we have collected and analyzed research data about the characterization and treatment of mouse models of polyQ diseases and organized them into two complementary Excel data tables. The data table that is presented in this review (Part I) covers the behavioral, molecular, cellular, and anatomic characteristics of polyQ mice and contains the most current knowledge about polyQ mouse models. The structure of this data table is designed in such a way that it can be filtered to allow for the immediate retrieval of the data corresponding to a single mouse model or to compare the shared and unique aspects of many polyQ models. The second data table, which is presented in another publication (Part II), covers therapeutic research in mouse models by summarizing all of the therapeutic strategies employed in the treatment of polyQ disorders, phenotypes that are used to examine the effects of the therapy, and therapeutic outcomes.
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Affiliation(s)
- Maciej Figiel
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.
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41
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Parievsky A, Cepeda C, Levine MS. Evidence from the R6/2 Mouse Model of Huntington's Disease for Using Abnormal Brain Metabolism as a Biomarker for Evaluating Therapeutic Approaches for Treatment. FUTURE NEUROLOGY 2012; 7:527-530. [PMID: 25892970 DOI: 10.2217/fnl.12.51] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant genetic disorder characterized by a progression of motor abnormalities as well as cognitive and psychiatric symptoms [1]. Presently, there is no cure for HD and no treatment to reverse its course or prevent its onset. HD has been characterized primarily by significant degeneration of the striatum. In addition, imaging studies have shown alterations in extra-striatal regions including the cortex [2, 3], hippocampus, and hypothalamus [4]. Although previous functional magnetic resonance imaging (fMRI) studies in patients have yielded complex and heterogeneous findings, identifying functional alterations may serve as a useful tool for tracking the progression of HD and assessing the effects of therapeutic interventions. In a recent article Cepeda-Prado et el. use novel and groundbreaking fMRI methods to elucidate functional, structural, and metabolic alterations in the R6/2 mouse model of HD. Based on changes in relative cerebral brain volume (rCBV), neuronal activity, and glucose utilization, the authors suggest that R6/2 mice have impaired neurometabolic coupling. They propose the use of rCBV as a biomarker of HD progression, providing a basis for future research examining functional alterations in animal models.
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Affiliation(s)
- Anna Parievsky
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior and the Brain Research Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior and the Brain Research Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Michael S Levine
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior and the Brain Research Institute, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
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42
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Zheng S, Ghitani N, Blackburn JS, Liu JP, Zeitlin SO. A series of N-terminal epitope tagged Hdh knock-in alleles expressing normal and mutant huntingtin: their application to understanding the effect of increasing the length of normal Huntingtin's polyglutamine stretch on CAG140 mouse model pathogenesis. Mol Brain 2012; 5:28. [PMID: 22892315 PMCID: PMC3499431 DOI: 10.1186/1756-6606-5-28] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 08/09/2012] [Indexed: 12/19/2022] Open
Abstract
Background Huntington’s disease (HD) is an autosomal dominant neurodegenerative disease that is caused by the expansion of a polyglutamine (polyQ) stretch within Huntingtin (htt), the protein product of the HD gene. Although studies in vitro have suggested that the mutant htt can act in a potentially dominant negative fashion by sequestering wild-type htt into insoluble protein aggregates, the role of the length of the normal htt polyQ stretch, and the adjacent proline-rich region (PRR) in modulating HD mouse model pathogenesis is currently unknown. Results We describe the generation and characterization of a series of knock-in HD mouse models that express versions of the mouse HD gene (Hdh) encoding N-terminal hemaglutinin (HA) or 3xFlag epitope tagged full-length htt with different polyQ lengths (HA7Q-, 3xFlag7Q-, 3xFlag20Q-, and 3xFlag140Q-htt) and substitution of the adjacent mouse PRR with the human PRR (3xFlag20Q- and 3xFlag140Q-htt). Using co-immunoprecipitation and immunohistochemistry analyses, we detect no significant interaction between soluble full-length normal 7Q- htt and mutant (140Q) htt, but we do observe N-terminal fragments of epitope-tagged normal htt in mutant htt aggregates. When the sequences encoding normal mouse htt’s polyQ stretch and PRR are replaced with non-pathogenic human sequence in mice also expressing 140Q-htt, aggregation foci within the striatum, and the mean size of htt inclusions are increased, along with an increase in striatal lipofuscin and gliosis. Conclusion In mice, soluble full-length normal and mutant htt are predominantly monomeric. In heterozygous knock-in HD mouse models, substituting the normal mouse polyQ and PRR with normal human sequence can exacerbate some neuropathological phenotypes.
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Affiliation(s)
- Shuqiu Zheng
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA 22908, Box 801392, USA
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Reiner A, Wang HB, Del Mar N, Sakata K, Yoo W, Deng YP. BDNF may play a differential role in the protective effect of the mGluR2/3 agonist LY379268 on striatal projection neurons in R6/2 Huntington's disease mice. Brain Res 2012; 1473:161-72. [PMID: 22820300 DOI: 10.1016/j.brainres.2012.07.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 07/04/2012] [Accepted: 07/12/2012] [Indexed: 10/28/2022]
Abstract
We have found that daily subcutaneous injection with a maximum tolerated dose (MTD) of the mGluR2/3 agonist LY379268 (20mg/kg) beginning at 4 weeks dramatically improves the phenotype in R6/2 mice. For example, we observed normalization of motor function in distance traveled, speed, the infrequency of pauses, and the ability to locomote in a straight line, and a rescue of a 15-20% striatal neuron loss at 10 weeks. As acute LY379268 treatment is known to increase cortical BDNF production, and BDNF is known to be beneficial for striatal neurons, we investigated if the benefit of daily LY379268 in R6/2 mice for striatal projection neurons was associated with increases in corticostriatal BDNF, with assessments done at 10 weeks of age after daily MTD treatment since the fourth week of life. We found that LY379268 increased BDNF expression in layer 5 neurons in motor cortex, which project to striatum, partly rescued a preferential loss of enkephalinergic striatal neurons, and enhanced substance P (SP) expression by SP striatal projection neurons. The enhanced survival of enkephalinergic striatal neurons was correlated with the cortical BDNF increase, but the enhanced SP expression by SP striatal neurons was not. Thus, LY379268 may protect the two main striatal projection neuron types by different mechanisms, enkephalinergic neurons by the trophic benefit of BDNF, and SP neurons by a mechanism not involving BDNF. The SP neuron benefit may perhaps instead involve the anti-excitotoxic action of mGluR2/3 receptor agonists.
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Affiliation(s)
- A Reiner
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, 855 Monroe Ave, Memphis, TN 38163, USA.
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Reiner A, Lafferty DC, Wang HB, Del Mar N, Deng YP. The group 2 metabotropic glutamate receptor agonist LY379268 rescues neuronal, neurochemical and motor abnormalities in R6/2 Huntington's disease mice. Neurobiol Dis 2012; 47:75-91. [PMID: 22472187 DOI: 10.1016/j.nbd.2012.03.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 03/14/2012] [Accepted: 03/17/2012] [Indexed: 12/11/2022] Open
Abstract
Excitotoxic injury to striatum by dysfunctional cortical input or aberrant glutamate uptake may contribute to Huntington's disease (HD) pathogenesis. Since corticostriatal terminals possess mGluR2/3 autoreceptors, whose activation dampens glutamate release, we tested the ability of the mGluR2/3 agonist LY379268 to improve the phenotype in R6/2 HD mice with 120-125 CAG repeats. Daily subcutaneous injection of a maximum tolerated dose (MTD) of LY379268 (20mg/kg) had no evident adverse effects in WT mice, and diverse benefits in R6/2 mice, both in a cohort of mice tested behaviorally until the end of R6/2 lifespan and in a cohort sacrificed at 10weeks of age for blinded histological analysis. MTD LY379268 yielded a significant 11% increase in R6/2 survival, an improvement on rotarod, normalization and/or improvement in locomotor parameters measured in open field (activity, speed, acceleration, endurance, and gait), a rescue of a 15-20% cortical and striatal neuron loss, normalization of SP striatal neuron neurochemistry, and to a lesser extent enkephalinergic striatal neuron neurochemistry. Deficits were greater in male than female R6/2 mice, and drug benefit tended to be greater in males. The improvements in SP striatal neurons, which facilitate movement, are consistent with the improved movement in LY379268-treated R6/2 mice. Our data indicate that mGluR2/3 agonists may be particularly useful for ameliorating the morphological, neurochemical and motor defects observed in HD.
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Affiliation(s)
- A Reiner
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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Cowin RM, Roscic A, Bui N, Graham D, Paganetti P, Jankowsky JL, Weiss A, Paylor R. Neuronal aggregates are associated with phenotypic onset in the R6/2 Huntington's disease transgenic mouse. Behav Brain Res 2012; 229:308-19. [PMID: 22306231 DOI: 10.1016/j.bbr.2011.12.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 12/28/2011] [Accepted: 12/30/2011] [Indexed: 11/13/2022]
Abstract
Huntington's disease (HD) is caused by the expansion of the polyglutamine tract expressed in the huntingtin protein. Data from patients show a strong negative correlation between CAG repeat size and age of disease onset. Recent studies in mixed background C57×CBA R6/2 mice suggest the inverse correlation observed in the human disease may not be replicated in some animal models of HD. To further clarify the relationship between repeat length and age of onset, congenic C57BL6/J R6/2 transgenic mice expressing 110, 260 or 310 CAG were tested in a comprehensive behavioral battery at multiple ages. Data confirmed the findings of earlier studies and indicate that on a pure C57BL6/J genetic background, R6/2 mice with larger repeats exhibit a delay in phenotypic onset with increasing polyglutamine size (6 weeks in 110 CAG and 17 weeks in 310 CAG mice). Further analysis confirmed a decrease in transgene transcript expression in 310 CAG mice as well as differential aggregated protein localization in association with repeat length. Mice expressing 110 CAG developed aggregates that localized almost exclusively to the nucleus of neuronal cells in the striatum and cortex. In contrast, tissue from 310 CAG mice exhibited predominantly extranuclear inclusions. Novel mutant protein analysis obtained using time-resolved fluorescence resonance energy transfer (FRET) revealed that soluble protein levels decreased with disease onset in R6/2 mice while aggregated protein levels increased. We believe that these data suggest a role for aggregation and inclusion localization in HD pathogenesis and propose a mechanism for the age of onset delay observed in R6/2 mice.
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Affiliation(s)
- Randi-Michelle Cowin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
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Cowin RM, Bui N, Graham D, Green JR, Grueninger S, Yuva-Paylor LA, Syed AU, Weiss A, Paylor R. Onset and progression of behavioral and molecular phenotypes in a novel congenic R6/2 line exhibiting intergenerational CAG repeat stability. PLoS One 2011; 6:e28409. [PMID: 22163300 PMCID: PMC3233565 DOI: 10.1371/journal.pone.0028409] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 11/07/2011] [Indexed: 12/20/2022] Open
Abstract
In the present study we report on the use of speed congenics to generate a C57BL/6J congenic line of HD-model R6/2 mice carrying 110 CAG repeats, which uniquely exhibits minimal intergenerational instability. We also report the first identification of the R6/2 transgene insertion site. The relatively stable line of 110 CAG R6/2 mice was characterized for the onset of behavioral impairments in motor, cognitive and psychiatric-related phenotypes as well as the progression of disease-related impairments from 4 to 10 weeks of age. 110Q mice exhibited many of the phenotypes commonly associated with the R6/2 model including reduced activity and impairments in rotarod performance. The onset of many of the phenotypes occurred around 6 weeks and was progressive across age. In addition, some phenotypes were observed in mice as early as 4 weeks of age. The present study also reports the onset and progression of changes in several molecular phenotypes in the novel R6/2 mice and the association of these changes with behavioral symptom onset and progression. Data from TR-FRET suggest an association of mutant protein state changes (soluble versus aggregated) in disease onset and progression.
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Affiliation(s)
- Randi-Michelle Cowin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Nghiem Bui
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Deanna Graham
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jennie R. Green
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Stephan Grueninger
- Novartis Institutes for BioMedical Research, Neuroscience Discovery, Basel, Switzerland
| | - Lisa A. Yuva-Paylor
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Arsalan U. Syed
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Andreas Weiss
- Novartis Institutes for BioMedical Research, Neuroscience Discovery, Basel, Switzerland
| | - Richard Paylor
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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Cummings DM, Alaghband Y, Hickey MA, Joshi PR, Hong SC, Zhu C, Ando TK, André VM, Cepeda C, Watson JB, Levine MS. A critical window of CAG repeat-length correlates with phenotype severity in the R6/2 mouse model of Huntington's disease. J Neurophysiol 2011; 107:677-91. [PMID: 22072510 DOI: 10.1152/jn.00762.2011] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The R6/2 mouse is the most frequently used model for experimental and preclinical drug trials in Huntington's disease (HD). When the R6/2 mouse was first developed, it carried exon 1 of the huntingtin gene with ~150 cytosine-adenine-guanine (CAG) repeats. The model presented with a rapid and aggressive phenotype that shared many features with the human condition and was particularly similar to juvenile HD. However, instability in the CAG repeat length due to different breeding practices has led to both decreases and increases in average CAG repeat lengths among colonies. Given the inverse relationship in human HD between CAG repeat length and age at onset and to a degree, the direct relationship with severity of disease, we have investigated the effect of altered CAG repeat length. Four lines, carrying ~110, ~160, ~210, and ~310 CAG repeats, were examined using a battery of tests designed to assess the basic R6/2 phenotype. These included electrophysiological properties of striatal medium-sized spiny neurons, motor activity, inclusion formation, and protein expression. The results showed an unpredicted, inverted "U-shaped" relationship between CAG repeat length and phenotype; increasing the CAG repeat length from 110 to 160 exacerbated the R6/2 phenotype, whereas further increases to 210 and 310 CAG repeats greatly ameliorated the phenotype. These findings demonstrate that the expected relationship between CAG repeat length and disease severity observed in humans is lost in the R6/2 mouse model and highlight the importance of CAG repeat-length determination in preclinical drug trials that use this model.
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Affiliation(s)
- Damian M Cummings
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, University of California at Los Angeles, California 90095, USA
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Giles P, Elliston L, Higgs GV, Brooks SP, Dunnett SB, Jones L. Longitudinal analysis of gene expression and behaviour in the HdhQ150 mouse model of Huntington's disease. Brain Res Bull 2011; 88:199-209. [PMID: 22001697 DOI: 10.1016/j.brainresbull.2011.10.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 09/28/2011] [Accepted: 10/01/2011] [Indexed: 12/17/2022]
Abstract
Substantial transcriptional changes are seen in Huntington's disease (HD) brain and parallel early changes in gene expression are observed in mouse models of HD. Analysis of behaviour in such models also shows substantial deficits in motor, learning and memory tasks. We examined the changes in the transcriptional profile in the HdhQ150 mouse model of HD at 6, 12 and 18 months and correlated these changes with the behavioural tasks the animals had undertaken. Changes in gene expression over time showed a significant enrichment of RNAs altered in abundance that related to cognition in both HdhQ150 and wild-type animals. The most significantly down-regulated mRNA between genotypes over the whole time-course was Htt itself. Other changes between genotypes identified at 6 months related to chromatin organization and structure, whilst at 18 months changes related mainly to intracellular signalling. Correlation of the changes in gene product abundance with phenotypic changes revealed that weight and detection of the opposite position of the platform in the water maze seemed to correlate with the chromatin alterations whereas changes in the rotarod performance related mainly to intracellular signalling and homeostasis. These results implicate alterations in specific molecular pathways that may underpin changes in different behavioural tasks.
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Affiliation(s)
- Peter Giles
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, UK
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Abstract
Huntington's disease (HD) is a devastating and incurable neurodegenerative disorder characterized by progressive cognitive, psychiatric and motor impairments. Although the disease has been seen as a disorder purely of the brain, there is now emerging evidence that abnormalities outside the central nervous system are commonly seen in HD. Indeed, the mutant huntingtin (mHtt) coded for by the abnormal gene in HD is found in every cell type where its presence has been sought. In particular, there are a number of recent observations in HD patients that mHtt interacts with the immune system with accumulating evidence that changes in the immune system may critically contribute to the pathology of HD. However, the nature of this contribution remains unclear, to the extent that it is not even known whether the immune system has a beneficial or detrimental role in HD patients. In this review, we attempt to bring a novel understanding to the interaction of the immune system to HD pathology, thereby shedding light on its potential pathogenic role. As part of this discussion, we revisit the clinical data on the anti-inflammatory drug trials in HD and propose new experimental approaches to interrogate the role of immunity in this currently incurable disorder.
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Tang B, Seredenina T, Coppola G, Kuhn A, Geschwind DH, Luthi-Carter R, Thomas EA. Gene expression profiling of R6/2 transgenic mice with different CAG repeat lengths reveals genes associated with disease onset and progression in Huntington's disease. Neurobiol Dis 2011; 42:459-67. [PMID: 21334439 DOI: 10.1016/j.nbd.2011.02.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 01/27/2011] [Accepted: 02/07/2011] [Indexed: 10/18/2022] Open
Abstract
R6/2 transgenic mice with expanded CAG repeats (>300) have a surprisingly prolonged disease progression and longer lifespan than prototypical parent R6/2 mice (carrying 150 CAGs); however, the mechanism of this phenotype amelioration is unknown. We compared gene expression profiles in the striatum of R6/2 transgenic mice carrying ~300 CAG repeats (R6/2(Q300) transgenic mice) to those carrying ~150 CAG repeats (R6/2(Q150) transgenic mice) and littermate wildtype controls in order to identify genes that may play determinant roles in the time course of phenotypic expression in these mice. Of the top genes showing concordant expression changes in the striatum of both R6/2 lines, 85% were decreased in expression, while discordant expression changes were observed mostly for genes upregulated in R6/2(Q300) transgenic mice. Upregulated genes in the R6/2(Q300) mice were associated with the ubiquitin ligase complex, cell adhesion, protein folding, and establishment of protein localization. We qPCR-validated increases in expression of genes related to the latter category, including Lrsam1, Erp29, Nasp, Tap1, Rab9b, and Pfdn5 in R6/2(Q300) mice, changes that were not observed in R6/2 mice with shorter CAG repeats, even in late stages (i.e., 12 weeks of age). We further tested Lrsam1 and Erp29, the two genes showing the greatest upregulation in R6/2(Q300) transgenic mice, for potential neuroprotective effects in primary striatal cultures overexpressing a mutated human huntingtin (htt) fragment. Overexpression of Lrsam1 prevented the loss of NeuN-positive cell bodies in htt171-82Q cultures, concomitant with a reduction of nuclear htt aggregates. Erp29 showed no significant effects in this model. This is consistent with the distinct pattern of htt inclusion localization observed in R6/2(Q300) transgenic mice, in which smaller cytoplasmic inclusions represent the major form of insoluble htt in the cell, as opposed to large nuclear inclusions observed in R6/2(Q150) transgenic mice. We suggest that the prolonged onset and disease course observed in R6/2 mice with greatly expanded CAG repeats might result from differential upregulation of genes related to protein localization and clearance. Such genes may represent novel therapeutic avenues to decrease htt aggregate toxicity and cell death in HD patients, with Lrsam1 being a promising, novel candidate disease modifier.
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Affiliation(s)
- Bin Tang
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA, USA
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