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Klonarakis M, De Vos M, Woo E, Ralph L, Thacker JS, Gil-Mohapel J. The three sisters of fate: Genetics, pathophysiology and outcomes of animal models of neurodegenerative diseases. Neurosci Biobehav Rev 2022; 135:104541. [DOI: 10.1016/j.neubiorev.2022.104541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 11/28/2021] [Accepted: 01/13/2022] [Indexed: 02/07/2023]
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Kim A, Lalonde K, Truesdell A, Gomes Welter P, Brocardo PS, Rosenstock TR, Gil-Mohapel J. New Avenues for the Treatment of Huntington's Disease. Int J Mol Sci 2021; 22:ijms22168363. [PMID: 34445070 PMCID: PMC8394361 DOI: 10.3390/ijms22168363] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/11/2022] Open
Abstract
Huntington’s disease (HD) is a neurodegenerative disorder caused by a CAG expansion in the HD gene. The disease is characterized by neurodegeneration, particularly in the striatum and cortex. The first symptoms usually appear in mid-life and include cognitive deficits and motor disturbances that progress over time. Despite being a genetic disorder with a known cause, several mechanisms are thought to contribute to neurodegeneration in HD, and numerous pre-clinical and clinical studies have been conducted and are currently underway to test the efficacy of therapeutic approaches targeting some of these mechanisms with varying degrees of success. Although current clinical trials may lead to the identification or refinement of treatments that are likely to improve the quality of life of those living with HD, major efforts continue to be invested at the pre-clinical level, with numerous studies testing novel approaches that show promise as disease-modifying strategies. This review offers a detailed overview of the currently approved treatment options for HD and the clinical trials for this neurodegenerative disorder that are underway and concludes by discussing potential disease-modifying treatments that have shown promise in pre-clinical studies, including increasing neurotropic support, modulating autophagy, epigenetic and genetic manipulations, and the use of nanocarriers and stem cells.
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Affiliation(s)
- Amy Kim
- Island Medical Program and Faculty of Medicine, University of British Columbia, Victoria, BC V8P 5C2, Canada; (A.K.); (K.L.)
| | - Kathryn Lalonde
- Island Medical Program and Faculty of Medicine, University of British Columbia, Victoria, BC V8P 5C2, Canada; (A.K.); (K.L.)
| | - Aaron Truesdell
- Division of Medical Sciences, University of Victoria, Victoria, BC V8P 5C2, Canada;
- Schulich School of Medicine and Dentistry, Western University, London, ON N6A 5C1, Canada
| | - Priscilla Gomes Welter
- Neuroscience Graduate Program, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil; (P.G.W.); (P.S.B.)
| | - Patricia S. Brocardo
- Neuroscience Graduate Program, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil; (P.G.W.); (P.S.B.)
| | - Tatiana R. Rosenstock
- Institute of Cancer and Genomic Science, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK;
- Department of Pharmacology, University of São Paulo, São Paulo 05508-000, Brazil
| | - Joana Gil-Mohapel
- Island Medical Program and Faculty of Medicine, University of British Columbia, Victoria, BC V8P 5C2, Canada; (A.K.); (K.L.)
- Division of Medical Sciences, University of Victoria, Victoria, BC V8P 5C2, Canada;
- Correspondence: ; Tel.: +1-250-472-4597; Fax: +1-250-472-5505
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Bozzi M, Sciandra F. Molecular Mechanisms Underlying Muscle Wasting in Huntington's Disease. Int J Mol Sci 2020; 21:ijms21218314. [PMID: 33167595 PMCID: PMC7664236 DOI: 10.3390/ijms21218314] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/03/2020] [Accepted: 11/03/2020] [Indexed: 12/13/2022] Open
Abstract
Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder caused by pathogenic expansions of the triplet cytosine-adenosine-guanosine (CAG) within the Huntingtin gene. These expansions lead to a prolongation of the poly-glutamine stretch at the N-terminus of Huntingtin causing protein misfolding and aggregation. Huntingtin and its pathological variants are widely expressed, but the central nervous system is mainly affected, as proved by the wide spectrum of neurological symptoms, including behavioral anomalies, cognitive decline and motor disorders. Other hallmarks of HD are loss of body weight and muscle atrophy. This review highlights some key elements that likely provide a major contribution to muscle atrophy, namely, alteration of the transcriptional processes, mitochondrial dysfunction, which is strictly correlated to loss of energy homeostasis, inflammation, apoptosis and defects in the processes responsible for the protein quality control. The improvement of muscular symptoms has proven to slow the disease progression and extend the life span of animal models of HD, underlining the importance of a deep comprehension of the molecular mechanisms driving deterioration of muscular tissue.
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Affiliation(s)
- Manuela Bozzi
- Dipartimento Universitario di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Sezione di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore di Roma, Largo F. Vito 1, 00168 Roma, Italy
- Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”– SCITEC Sede di Roma, Largo F. Vito 1, 00168 Roma, Italy;
- Correspondence:
| | - Francesca Sciandra
- Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”– SCITEC Sede di Roma, Largo F. Vito 1, 00168 Roma, Italy;
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Kedaigle AJ, Reidling JC, Lim RG, Adam M, Wu J, Wassie B, Stocksdale JT, Casale MS, Fraenkel E, Thompson LM. Treatment with JQ1, a BET bromodomain inhibitor, is selectively detrimental to R6/2 Huntington's disease mice. Hum Mol Genet 2020; 29:202-215. [PMID: 31696228 DOI: 10.1093/hmg/ddz264] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 09/20/2019] [Accepted: 10/23/2019] [Indexed: 12/22/2022] Open
Abstract
Transcriptional and epigenetic alterations occur early in Huntington's disease (HD), and treatment with epigenetic modulators is beneficial in several HD animal models. The drug JQ1, which inhibits histone acetyl-lysine reader bromodomains, has shown promise for multiple cancers and neurodegenerative disease. We tested whether JQ1 could improve behavioral phenotypes in the R6/2 mouse model of HD and modulate HD-associated changes in transcription and epigenomics. R6/2 and non-transgenic (NT) mice were treated with JQ1 daily from 5 to 11 weeks of age and behavioral phenotypes evaluated over this period. Following the trial, cortex and striatum were isolated and subjected to mRNA-seq and ChIP-seq for the histone marks H3K4me3 and H3K27ac. Initially, JQ1 enhanced motor performance in NT mice. In R6/2 mice, however, JQ1 had no effect on rotarod or grip strength but exacerbated weight loss and worsened performance on the pole test. JQ1-induced gene expression changes in NT mice were distinct from those in R6/2 and primarily involved protein translation and bioenergetics pathways. Dysregulation of HD-related pathways in striatum was exacerbated by JQ1 in R6/2 mice, but not in NTs, and JQ1 caused a corresponding increase in the formation of a mutant huntingtin protein-dependent high molecular weight species associated with pathogenesis. This study suggests that drugs predicted to be beneficial based on their mode of action and effects in wild-type or in other neurodegenerative disease models may have an altered impact in the HD context. These observations have important implications in the development of epigenetic modulators as therapies for HD.
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Affiliation(s)
| | | | - Ryan G Lim
- Memory Impairment and Neurological Disorders Research Unit
| | - Miriam Adam
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Jie Wu
- Memory Impairment and Neurological Disorders Research Unit
| | - Brook Wassie
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | | | | | - Ernest Fraenkel
- Computational and Systems Biology Program.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Leslie M Thompson
- Memory Impairment and Neurological Disorders Research Unit.,Departments of Psychiatry and Human Behavior and Neurobiology and Behavior, University of California Irvine, Irvine, CA 92697, USA
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Lamirault C, Nguyen HP, Doyère V, El Massioui N. Age-related alteration of emotional regulation in the BACHD rat model of Huntington disease. GENES, BRAIN, AND BEHAVIOR 2020; 19:e12633. [PMID: 31883197 DOI: 10.1111/gbb.12633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 10/29/2019] [Accepted: 12/23/2019] [Indexed: 06/10/2023]
Abstract
Huntington's disease (HD) is a genetic neurodegenerative disorder, caused by an expanded CAG repeat in the gene encoding the huntingtin protein. At the premanifest phase, before motor symptoms occur, psychiatric and emotional disorders are observed with high prevalence in HD patients. Agitation, anxiety and irritability are often described but also depression and/or apathy, associated with a lack of emotional control. The aim of the present study was to better circumscribe and understand the emotional symptoms and assess their evolution according to the progression of the disease using a transgenic HD model, BACHD rats, at the age of 4, 12 and 18 months. To achieve this goal, we confronted animals to two types of tests: first, tests assessing anxiety like the light/dark box and the conflict test, which are situations that did not involve an obvious threat and tests assessing the reactivity to a present threat using confrontation with an unknown conspecific (social behavior test) or with an aversive stimulus (fear conditioning test). In all animals, results show an age-dependent anxiety-like behavior, particularly marked in situation requiring passive responses (light/dark box and fear conditioning tests). BACHD rats exhibited a more profound alteration than WT animals in these tests from an early stage of the disease whereas, in tasks requiring some kind of motivation (for food or for social contacts), only old BACHD rats showed high anxiety-like behavior compared to WT, may be partly due to the other symptoms' occurrence at this stage: locomotor difficulties and/or apathy.
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Affiliation(s)
- Charlotte Lamirault
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris-Saclay, Gif-sur-Yvette, France
| | - Huu Phuc Nguyen
- Department of Human Genetics, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany
| | - Valérie Doyère
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris-Saclay, Gif-sur-Yvette, France
| | - Nicole El Massioui
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris-Saclay, Gif-sur-Yvette, France
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Rebec GV. Corticostriatal network dysfunction in Huntington's disease: Deficits in neural processing, glutamate transport, and ascorbate release. CNS Neurosci Ther 2018; 24:281-291. [PMID: 29464896 PMCID: PMC6489880 DOI: 10.1111/cns.12828] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/10/2018] [Accepted: 01/27/2018] [Indexed: 12/25/2022] Open
Abstract
AIMS This review summarizes evidence for dysfunctional connectivity between cortical and striatal neurons in Huntington's disease (HD), a fatal neurodegenerative condition caused by a single gene mutation. The focus is on data derived from recording of electrophysiological signals in behaving transgenic mouse models. DISCUSSIONS Firing patterns of individual neurons and the frequency oscillations of local field potentials indicate a disruption in corticostriatal processing driven, in large part, by interactions between cells that contain the mutant gene rather than the mutant gene alone. Dysregulation of glutamate, an excitatory amino acid released by cortical afferents, plays a key role in the breakdown of corticostriatal communication, a process modulated by ascorbate, an antioxidant vitamin found in high concentration in striatum. Up-regulation of glutamate transport by drug administration or viral-vector delivery improves ascorbate homeostasis and neurobehavioral processing in HD mice. Further analysis of electrophysiological data, including the use of sophisticated computational strategies, is required to discern how behavioral demands modulate the flow of corticostriatal information and its disruption by HD. CONCLUSIONS Long before massive cell loss occurs, HD impairs the mechanisms by which cortical and striatal neurons communicate. A key problem identified in transgenic animal models is dysregulation of the dynamic changes in extracellular glutamate and ascorbate. Improved understanding of how these neurochemical systems impact corticostriatal communication is necessary before an effective therapeutic strategy can emerge.
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Affiliation(s)
- George V. Rebec
- Program in NeuroscienceDepartment of Psychological and Brain SciencesIndiana UniversityBloomingtonINUSA
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Reidling JC, Relaño-Ginés A, Holley SM, Ochaba J, Moore C, Fury B, Lau A, Tran AH, Yeung S, Salamati D, Zhu C, Hatami A, Cepeda C, Barry JA, Kamdjou T, King A, Coleal-Bergum D, Franich NR, LaFerla FM, Steffan JS, Blurton-Jones M, Meshul CK, Bauer G, Levine MS, Chesselet MF, Thompson LM. Human Neural Stem Cell Transplantation Rescues Functional Deficits in R6/2 and Q140 Huntington's Disease Mice. Stem Cell Reports 2017; 10:58-72. [PMID: 29233555 PMCID: PMC5768890 DOI: 10.1016/j.stemcr.2017.11.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 11/03/2017] [Accepted: 11/03/2017] [Indexed: 01/01/2023] Open
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disorder with no disease-modifying treatment. Expansion of the glutamine-encoding repeat in the Huntingtin (HTT) gene causes broad effects that are a challenge for single treatment strategies. Strategies based on human stem cells offer a promising option. We evaluated efficacy of transplanting a good manufacturing practice (GMP)-grade human embryonic stem cell-derived neural stem cell (hNSC) line into striatum of HD modeled mice. In HD fragment model R6/2 mice, transplants improve motor deficits, rescue synaptic alterations, and are contacted by nerve terminals from mouse cells. Furthermore, implanted hNSCs are electrophysiologically active. hNSCs also improved motor and late-stage cognitive impairment in a second HD model, Q140 knockin mice. Disease-modifying activity is suggested by the reduction of aberrant accumulation of mutant HTT protein and expression of brain-derived neurotrophic factor (BDNF) in both models. These findings hold promise for future development of stem cell-based therapies.
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Affiliation(s)
- Jack C Reidling
- Institute for Memory Impairment and Neurological Disorders, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA
| | - Aroa Relaño-Ginés
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 710 Westwood Plaza, Los Angeles, CA 90095-1769, USA
| | - Sandra M Holley
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, 760 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Joseph Ochaba
- Department of Neurobiology & Behavior, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA
| | - Cindy Moore
- Portland VA Medical Center, 3710 SW US Veterans Hospital Road, Portland, OR 97239, USA
| | - Brian Fury
- Institute for Regenerative Cures, University of California, Davis, 2921 Stockton Boulevard, Sacramento, CA 95817, USA
| | - Alice Lau
- Department of Psychiatry & Human Behavior, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA
| | - Andrew H Tran
- Institute for Memory Impairment and Neurological Disorders, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA
| | - Sylvia Yeung
- Institute for Memory Impairment and Neurological Disorders, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA
| | - Delaram Salamati
- Institute for Memory Impairment and Neurological Disorders, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA
| | - Chunni Zhu
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 710 Westwood Plaza, Los Angeles, CA 90095-1769, USA
| | - Asa Hatami
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 710 Westwood Plaza, Los Angeles, CA 90095-1769, USA
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, 760 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Joshua A Barry
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, 760 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Talia Kamdjou
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, 760 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Alvin King
- Department of Neurobiology & Behavior, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA
| | - Dane Coleal-Bergum
- Institute for Regenerative Cures, University of California, Davis, 2921 Stockton Boulevard, Sacramento, CA 95817, USA
| | - Nicholas R Franich
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 710 Westwood Plaza, Los Angeles, CA 90095-1769, USA
| | - Frank M LaFerla
- Institute for Memory Impairment and Neurological Disorders, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA; Department of Neurobiology & Behavior, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA
| | - Joan S Steffan
- Institute for Memory Impairment and Neurological Disorders, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA; Department of Psychiatry & Human Behavior, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA
| | - Mathew Blurton-Jones
- Institute for Memory Impairment and Neurological Disorders, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA; Department of Neurobiology & Behavior, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA; Sue and Bill Gross Stem Cell Center, University of California, Irvine, Gross Hall, Room 3219, 845 Health Sciences Road, Irvine, CA 92697, USA
| | - Charles K Meshul
- Portland VA Medical Center, 3710 SW US Veterans Hospital Road, Portland, OR 97239, USA; Oregon Health & Science University, Department of Behavioral Neuroscience, 3181 SW Sam Jackson Park Road, L470, Portland, OR 97239, USA
| | - Gerhard Bauer
- Institute for Regenerative Cures, University of California, Davis, 2921 Stockton Boulevard, Sacramento, CA 95817, USA
| | - Michael S Levine
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, 760 Westwood Plaza, Los Angeles, CA 90095, USA; Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, 760 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Marie-Francoise Chesselet
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 710 Westwood Plaza, Los Angeles, CA 90095-1769, USA
| | - Leslie M Thompson
- Institute for Memory Impairment and Neurological Disorders, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA; Department of Neurobiology & Behavior, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA; Department of Psychiatry & Human Behavior, University of California, Irvine, 3400 Biological Sciences III, Irvine, CA 92697-4545, USA; Sue and Bill Gross Stem Cell Center, University of California, Irvine, Gross Hall, Room 3219, 845 Health Sciences Road, Irvine, CA 92697, USA.
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Ramaswamy S, Shannon KM, Kordower JH. Huntington's Disease: Pathological Mechanisms and Therapeutic Strategies. Cell Transplant 2017; 16:301-12. [PMID: 17503740 DOI: 10.3727/000000007783464687] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Huntington's disease (HD) is a devastating neurodegenerative disorder that occurs in patients with a mutation in the huntingtin or IT15 gene. Patients are plagued by early cognitive signs, motor deficits, and psychiatric disturbances. Symptoms are attributed to cell death in the striatum and disruption of cortical–striatal circuitry. Mechanisms of cell death are unclear, but processes involving mitochondrial abnormalities, excitotoxicity, and abnormal protein degradation have been implicated. Many factors likely contribute to neuron death and dysfunction, and this has made it difficult to systematically address the pathology in HD. Pharmaceutical therapies are commonly used in patients to treat disease symptoms. These have limited benefit and do not address the inexorable disease progression. Several neuroprotective therapies are being evaluated in animal models of HD as well as in clinical trials. Similarly, cell replacement strategies such as fetal transplantation have been used in the clinic with minimal success, making future cell replacement strategies such as stem cell therapy uncertain. This review describes the disease pathology in HD and addresses many of the past and emerging therapeutic strategies.
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Affiliation(s)
- Shilpa Ramaswamy
- Department of Neuroscience, Rush University Medical Center, Chicago, IL 60612, USA
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Yhnell E, Dunnett SB, Brooks SP. The utilisation of operant delayed matching and non-matching to position for probing cognitive flexibility and working memory in mouse models of Huntington's disease. J Neurosci Methods 2016; 265:72-80. [PMID: 26321735 PMCID: PMC4863528 DOI: 10.1016/j.jneumeth.2015.08.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 08/18/2015] [Accepted: 08/19/2015] [Indexed: 11/29/2022]
Abstract
BACKGROUND Operant behavioural testing provides a highly sensitive and automated method of exploring the behavioural deficits seen in rodent models of neurodegenerative diseases, including Huntington's disease (HD). The delayed matching to position (DMTP) and delayed non-matching to position (DNMTP) tasks probe spatial learning and working memory and when applied serially they can be used to measure reversal learning, which has been shown to be an early symptom of executive dysfunction in HD. NEW METHOD The DMTP and DNMTP tasks were conducted in two configurations of operant apparatus; the conventional 9-hole operant apparatus, and a Skinner-like operant apparatus, to compare, contrast and optimise the DMTP and DNMTP operant protocols for use in mice. The optimised tasks were then tested in the Hdh(Q111) mouse model of HD. RESULTS Optimisation of the operant apparatus demonstrated that the mice learned the DMTP and DNMTP tasks more rapidly and effectively in the Skinner-like apparatus configuration in comparison to the conventional 9-hole apparatus configuration. When tested in the Hdh(Q111) mouse model of HD, the DMTP and DNMTP tasks revealed significant deficits in reversal learning. COMPARISON WITH EXISTING METHOD We found that mice were capable of performing the DMTP and DNMTP tasks in both apparatus configurations, but in comparison to the 9-hole configuration, the Skinner-like configuration produced more efficient, robust and reliable results. CONCLUSIONS The results presented here suggest that DMTP and DNMTP tasks, incorporating a reversal learning manipulation, are valid and robust methods for probing selected cognitive deficits in mouse models of neurodegenerative diseases.
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Affiliation(s)
- Emma Yhnell
- The Brain Repair Group, Cardiff University School of Biosciences, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, South Glamorgan, United Kingdom.
| | - Stephen B Dunnett
- The Brain Repair Group, Cardiff University School of Biosciences, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, South Glamorgan, United Kingdom
| | - Simon P Brooks
- The Brain Repair Group, Cardiff University School of Biosciences, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, South Glamorgan, United Kingdom
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Wolf RC, Klöppel S. Clinical significance of frontal cortex abnormalities in Huntington's disease. Exp Neurol 2013; 247:39-44. [PMID: 23562669 DOI: 10.1016/j.expneurol.2013.03.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/03/2013] [Accepted: 03/25/2013] [Indexed: 01/28/2023]
Affiliation(s)
- Robert Christian Wolf
- Center of Psychosocial Medicine, Department of General Psychiatry, University of Heidelberg, Germany
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11
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Comprehensive behavioral and molecular characterization of a new knock-in mouse model of Huntington's disease: zQ175. PLoS One 2012; 7:e49838. [PMID: 23284626 PMCID: PMC3527464 DOI: 10.1371/journal.pone.0049838] [Citation(s) in RCA: 301] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 10/12/2012] [Indexed: 11/19/2022] Open
Abstract
Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder characterized by motor, cognitive and psychiatric manifestations. Since the mutation responsible for the disease was identified as an unstable expansion of CAG repeats in the gene encoding the huntingtin protein in 1993, numerous mouse models of HD have been generated to study disease pathogenesis and evaluate potential therapeutic approaches. Of these, knock-in models best mimic the human condition from a genetic perspective since they express the mutation in the appropriate genetic and protein context. Behaviorally, however, while some abnormal phenotypes have been detected in knock-in mouse models, a model with an earlier and more robust phenotype than the existing models is required. We describe here for the first time a new mouse line, the zQ175 knock-in mouse, derived from a spontaneous expansion of the CAG copy number in our CAG 140 knock-in colony [1]. Given the inverse relationship typically observed between age of HD onset and length of CAG repeat, since this new mouse line carries a significantly higher CAG repeat length it was expected to be more significantly impaired than the parent line. Using a battery of behavioral tests we evaluated both heterozygous and homozygous zQ175 mice. Homozygous mice showed motor and grip strength abnormalities with an early onset (8 and 4 weeks of age, respectively), which were followed by deficits in rotarod and climbing activity at 30 weeks of age and by cognitive deficits at around 1 year of age. Of particular interest for translational work, we also found clear behavioral deficits in heterozygous mice from around 4.5 months of age, especially in the dark phase of the diurnal cycle. Decreased body weight was observed in both heterozygotes and homozygotes, along with significantly reduced survival in the homozygotes. In addition, we detected an early and significant decrease of striatal gene markers from 12 weeks of age. These data suggest that the zQ175 knock-in line could be a suitable model for the evaluation of therapeutic approaches and early events in the pathogenesis of HD.
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12
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Gil-Mohapel JM. Screening of therapeutic strategies for Huntington's disease in YAC128 transgenic mice. CNS Neurosci Ther 2012; 18:77-86. [PMID: 21501423 DOI: 10.1111/j.1755-5949.2011.00246.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Huntington’s disease (HD) is a hereditary neurodegenerative disorder caused by an unstable expansion of cytosine-adenine-guanine (CAG) repeats in the HD gene. The symptoms include cognitive dysfunction and severe motor impairment with loss of voluntary movement coordination that is later replaced by bradykinesia and rigidity. The neuropathology is characterized by neuronal loss mainly in the striatum and cortex, and the appearance of neuronal intranuclear inclusions of mutant huntingtin. The mechanisms responsible for neurodegeneration are still not fully understood although excitotoxicity and a consequent increase in intracellular calcium concentration as well as the activation of caspases and calapins are known to play a key role. There is currently no satisfactory treatment or cure for this disease. The YAC128 transgenic mice express the full-length human HD gene with 128 CAG repeats and constitute a unique model for the study of HD as they replicate the slow and biphasic progression of behavioral deficits characteristic of the human condition and show striatal neuronal loss. As such, these transgenic mice have been an invaluable model not only for the elucidation of the neurodegenerative pathways in HD, but also for the screening and development of new therapeutic approaches. Here, I will review the unique characteristics of this transgenic HD model and will provide a summary of the therapies that have been tested in these mice, namely: potentiation of the protective roles of wild-type huntingtin and mutant huntingtin aggregation, transglutaminase inhibition, inhibition of glutamate- and dopamine-induced toxicity, apoptosis inhibition, use of essential fatty acids, and the novel approach of intrabody gene therapy. The insights obtained from these and future studies will help identify potential candidates for clinical trials and will ultimately contribute to the discovery of a successful treatment for this devastating neurodegenerative disorder.
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Affiliation(s)
- Joana M Gil-Mohapel
- Division of Medical Sciences, Island Medical Program, University of Victoria, British Columbia, Canada.
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13
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Murphy-Nakhnikian A, Dorner JL, Fischer BI, Bower-Bir ND, Rebec GV. Abnormal burst patterns of single neurons recorded in the substantia nigra reticulata of behaving 140 CAG Huntington's disease mice. Neurosci Lett 2012; 512:1-5. [PMID: 22327034 DOI: 10.1016/j.neulet.2011.12.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 12/01/2011] [Accepted: 12/22/2011] [Indexed: 11/19/2022]
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disorder that causes neurological pathology in the basal ganglia and related circuitry. A key site of HD pathology is striatum, the principal basal ganglia input structure; striatal pathology likely changes basal ganglia output but no existing studies address this issue. In this report, we characterize single-neuron activity in the substantia nigra reticulata (SNr) of awake, freely behaving 140 CAG knock-in (KI) mice at 16-40 weeks. KI mice are a well characterized model of adult HD and are mildly symptomatic in this age range. As the primary basal ganglia output nucleus in rodents, the SNr receives direct innervation from striatum, as well as indirect influence via polysynaptic inputs. We analyzed 32 single neurons recorded from KI animals and 44 from wild-type (WT) controls. We found increased burst rates, without a concordant change in spike discharge rate, in KI animals relative to WTs. Furthermore, although metrics of burst structure, such as the inter-spike interval in bursts, do not differ between groups, burst rate increases with age in KI, but not WT, animals. Our findings suggest that altered basal ganglia output is a physiological feature of early HD pathology.
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14
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Gil-Mohapel J, Simpson JM, Ghilan M, Christie BR. Neurogenesis in Huntington's disease: Can studying adult neurogenesis lead to the development of new therapeutic strategies? Brain Res 2011; 1406:84-105. [DOI: 10.1016/j.brainres.2011.06.040] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 06/14/2011] [Accepted: 06/15/2011] [Indexed: 01/01/2023]
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15
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Anitha M, Nandhu MS, Anju TR, Jes P, Paulose CS. Targeting glutamate mediated excitotoxicity in Huntington's disease: neural progenitors and partial glutamate antagonist--memantine. Med Hypotheses 2010; 76:138-40. [PMID: 20943326 DOI: 10.1016/j.mehy.2010.09.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 08/30/2010] [Accepted: 09/05/2010] [Indexed: 11/25/2022]
Abstract
Huntington's disease (HD) is a fatal progressive neurodegenerative disorder with autosomal dominant inheritance. In humans mutated huntingtin (htt) induces a preferential loss of medium spiny neurons (MSN) of the striatum and causes motor, cognitive and emotional deficits. One of the proposed cellular mechanism underlying medium spiny neurons degeneration is excitotoxic pathways mediated by glutamate receptors. The hypothesis proposed is restoration of medium spiny neurons in Huntington's disease using neural progenitor cell implantation and attenuation of glutamate mediated excitotoxicity using a partial glutamate antagonist - Memantine. Memantine can block the NMDA receptors and will prevent excess calcium influx into the neurons decreases the vulnerability of medium spiny neurons to glutamate mediated excitotoxicity. Neural progenitor cell implantation can enhance endogenous neurogenesis process replacing the degenerated medium spiny neurons in the striatum. This has immense significance in the management of Huntington's disease.
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Affiliation(s)
- M Anitha
- Molecular Neurobiology and Cell Biology Unit, Center for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin 682 022, Kerala, India
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16
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Hernández-Echeagaray E, González N, Ruelas A, Mendoza E, Rodríguez-Martínez E, Antuna-Bizarro R. Low doses of 3-nitropropionic acid in vivo induce damage in mouse skeletal muscle. Neurol Sci 2010; 32:241-54. [PMID: 20734097 DOI: 10.1007/s10072-010-0394-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 07/23/2010] [Indexed: 02/07/2023]
Abstract
Mitochondrial alterations are believed to play a critical role in the pathophysiology of neurodegenerative diseases and in some well-described myopathies. In the present study, we evaluated muscle changes in vivo after blocking the mitochondrial complex II of the respiratory chain by using 3-nitropropionic acid (3-NP). This neurotoxin has been used as a pharmacological tool in animal models to address some of the metabolic modifications that might underlie central neurodegeneration; however, changes in peripheral musculature have not been documented. We believe that skeletal muscles must be affected because their integrity highly depends on oxidative metabolism. Therefore, histochemical, ultrastructural, and biochemical changes were studied in the muscles of mice treated with low doses of 3-NP (15 mg/kg, i.p., for 5 days). 3-NP-treated mice displayed changes in alkaline phosphatase (APase), succinic dehydrogenase (SDH), and cytochrome c oxidase (COX) levels in the gracilis and gastrocnemius muscles. These changes were statistically significant for APase and SDH in both muscles and for COX only in the gastrocnemius. No significant alterations in acetylcholinesterase (AChE) expression were observed in either muscle. Analysis of the muscle ultrastructure revealed mitochondrial atrophy as well as sarcomere and nuclei disorganization. At the biochemical level, nitric oxide (NO) and lipid peroxidation (LPO) changed in the muscles of 3-NP-treated mice, suggesting metabolic alterations due to oxidative stress. Early damage in the striatal tissue and behavioral modifications are also documented.
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Affiliation(s)
- Elizabeth Hernández-Echeagaray
- Laboratorio de Neurofisiología del Desarrollo y la Neurodegeneración, Unidad de Biomedicina, FES-I, Universidad Nacional Autónoma de México, Av. De Los Barrios # 1, Los Reyes Iztacala, C. P. 54090, Tlalnepantla, Mexico.
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17
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Alterations in striatal synaptic transmission are consistent across genetic mouse models of Huntington's disease. ASN Neuro 2010; 2:e00036. [PMID: 20585470 PMCID: PMC2888168 DOI: 10.1042/an20100007] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 04/23/2010] [Accepted: 05/05/2010] [Indexed: 11/28/2022] Open
Abstract
Since the identification of the gene responsible for HD (Huntington's
disease), many genetic mouse models have been generated. Each employs a unique
approach for delivery of the mutated gene and has a different CAG repeat length
and background strain. The resultant diversity in the genetic context and
phenotypes of these models has led to extensive debate regarding the relevance
of each model to the human disorder. Here, we compare and contrast the striatal
synaptic phenotypes of two models of HD, namely the YAC128 mouse, which carries
the full-length huntingtin gene on a yeast artificial chromosome, and the CAG140
KI (knock-in) mouse, which carries a human/mouse chimaeric gene that is
expressed in the context of the mouse genome, with our previously published data
obtained from the R6/2 mouse, which is transgenic for exon 1 mutant huntingtin.
We show that striatal MSNs (medium-sized spiny neurons) in YAC128 and CAG140 KI
mice have similar electrophysiological phenotypes to that of the R6/2 mouse.
These include a progressive increase in membrane input resistance, a reduction
in membrane capacitance, a lower frequency of spontaneous excitatory
postsynaptic currents and a greater frequency of spontaneous inhibitory
postsynaptic currents in a subpopulation of striatal neurons. Thus, despite
differences in the context of the inserted gene between these three models of
HD, the primary electrophysiological changes observed in striatal MSNs are
consistent. The outcomes suggest that the changes are due to the expression of
mutant huntingtin and such alterations can be extended to the human
condition.
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Key Words
- ACSF, artificial cerebrospinal fluid
- AP5, dl-2-amino-5-phosphonovaleric acid
- BIC, bicuculline methobromide
- CAG 140 knock-in mouse model
- CNQX, 6-cyano-7-nitroquinoxaline-2,3-dione
- EPSC, excitatory postsynaptic current
- GABAA, γ-aminobutyric acid type A
- HD, Huntington's disease
- HF, high frequency
- Huntington's disease
- IPSC, inhibitory postsynaptic current
- KI, knock-in
- LF, low frequency
- MSN, medium-sized spiny neuron
- WT, wild-type
- YAC128 mouse model
- electrophysiology
- striatum
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18
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Savas JN, Ma B, Deinhardt K, Culver BP, Restituito S, Wu L, Belasco JG, Chao MV, Tanese N. A role for huntington disease protein in dendritic RNA granules. J Biol Chem 2010; 285:13142-53. [PMID: 20185826 DOI: 10.1074/jbc.m110.114561] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Regulated transport and local translation of mRNA in neurons are critical for modulating synaptic strength, maintaining proper neural circuitry, and establishing long term memory. Neuronal RNA granules are ribonucleoprotein particles that serve to transport mRNA along microtubules and control local protein synthesis in response to synaptic activity. Studies suggest that neuronal RNA granules share similar structures and functions with somatic P-bodies. We recently reported that the Huntington disease protein huntingtin (Htt) associates with Argonaute (Ago) and localizes to cytoplasmic P-bodies, which serve as sites of mRNA storage, degradation, and small RNA-mediated gene silencing. Here we report that wild-type Htt associates with Ago2 and components of neuronal granules and co-traffics with mRNA in dendrites. Htt was found to co-localize with RNA containing the 3'-untranslated region sequence of known dendritically targeted mRNAs. Knockdown of Htt in neurons caused altered localization of mRNA. When tethered to a reporter construct, Htt down-regulated reporter gene expression in a manner dependent on Ago2, suggesting that Htt may function to repress translation of mRNAs during transport in neuronal granules.
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Affiliation(s)
- Jeffrey N Savas
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
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19
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Paulsen JS. Functional imaging in Huntington's disease. Exp Neurol 2009; 216:272-7. [PMID: 19171138 DOI: 10.1016/j.expneurol.2008.12.015] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Revised: 12/10/2008] [Accepted: 12/21/2008] [Indexed: 01/26/2023]
Abstract
Huntington's disease (HD) is a genetic brain disease characterized by loss of capacity in movement control, cognition, and emotional regulation over a period of about 30 years. Since it is well established that clinical impairments and brain atrophy can be detected decades prior to receiving a clinical diagnosis, functional neuroimaging efforts have gained momentum in HD research. In most brain disorders, there is accumulating evidence that the clinical manifestations of disease do not simply depend on the extent of tissue loss, but represent a complex balance among neuronal dysfunction, tissue repair, and circuitry reorganization. Based upon this premise, functional neuroimaging modalities may be more sensitive to the earliest changes in HD than are structural imaging approaches. For this review, PET and fMRI studies conducted in HD samples were summarized. Strengths and limitations of the utilization of functional imaging in HD are discussed and recommendations are offered to facilitate future research endeavors.
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Affiliation(s)
- Jane S Paulsen
- Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA.
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20
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Altered information processing in the prefrontal cortex of Huntington's disease mouse models. J Neurosci 2008; 28:8973-82. [PMID: 18768691 DOI: 10.1523/jneurosci.2804-08.2008] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Understanding cortical information processing in Huntington's disease (HD), a genetic neurological disorder characterized by prominent motor and cognitive abnormalities, is key to understanding the mechanisms underlying the HD behavioral phenotype. We recorded extracellular spike activity in two symptomatic, freely behaving mouse models: R6/2 transgenics, which are based on a CBA x C57BL/6 background and show robust behavioral symptoms, and HD knock-in (KI) mice, which have a 129sv background and express relatively mild behavioral signs. We focused on prefrontal cortex and assessed firing patterns of individually recorded neurons as well as the amount of synchrony between simultaneously recorded neuronal pairs. At the single-unit level, spike trains in R6/2 transgenics were less variable and had a faster rate than their corresponding wild-type (WT) littermates but showed significantly less bursting. In contrast, KI and WT firing patterns were closely matched. An assessment of both WTs revealed that the R6/2 and KI difference could not be explained by a difference in WT electrophysiology. Thus, the altered pattern of individual spike trains in R6/2 mice appears to parallel their aggressive form of symptom expression. Both WT lines, however, showed a high proportion of synchrony between neuronal pairs (>85%) that was significantly attenuated in both corresponding HD models (decreases of approximately 20% and approximately 30% in R6/2s and knock-ins, respectively). The loss of spike synchrony, regardless of symptom severity, suggests a population-level deficit in cortical information processing that underlies HD progression.
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Hickey MA, Kosmalska A, Enayati J, Cohen R, Zeitlin S, Levine MS, Chesselet MF. Extensive early motor and non-motor behavioral deficits are followed by striatal neuronal loss in knock-in Huntington's disease mice. Neuroscience 2008; 157:280-95. [PMID: 18805465 DOI: 10.1016/j.neuroscience.2008.08.041] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2008] [Revised: 08/20/2008] [Accepted: 08/21/2008] [Indexed: 01/06/2023]
Abstract
Huntington's disease is a neurodegenerative disorder, caused by an elongation of CAG repeats in the huntingtin gene. Mice with an insertion of an expanded polyglutamine repeat in the mouse huntingtin gene (knock-in mice) most closely model the disease because the mutation is expressed in the proper genomic and protein context. However, few knock-in mouse lines have been extensively characterized and available data suggest marked differences in the extent and time course of their behavioral and pathological phenotype. We have previously described behavioral anomalies in the open field as early as 1 month of age, followed by the appearance at 2 months of progressive huntingtin neuropathology, in a mouse carrying a portion of human exon 1 with approximately 140 CAG repeats inserted into the mouse huntingtin gene. Here we extend these observations by showing that early behavioral anomalies exist in a wide range of motor (climbing, vertical pole, rotarod, and running wheel performance) and non-motor functions (fear conditioning and anxiety) starting at 1-4 months of age, and are followed by progressive gliosis and decrease in dopamine and cyclic AMP-regulated phosphoprotein with molecular weight 32 kDa (DARPP32) (12 months) and a loss of striatal neurons at 2 years. At this age, mice also present striking spontaneous behavioral deficits in their home cage. The data show that this line of knock-in mice reproduces canonical characteristics of Huntington's disease, preceded by deficits which may correspond to the protracted pre-manifest phase of the disease in humans. Accordingly, they provide a useful model to elucidate early mechanisms of pathophysiology and the progression to overt neurodegeneration.
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Affiliation(s)
- M A Hickey
- Department of Neurology, University of California, Los Angeles, David Geffen School of Medicine, Reed Neurological Research Center B114, 710 Westwood Plaza, Los Angeles, CA 90095, USA
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22
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Wolf RC, Sambataro F, Vasic N, Schönfeldt-Lecuona C, Ecker D, Landwehrmeyer B. Aberrant connectivity of lateral prefrontal networks in presymptomatic Huntington's disease. Exp Neurol 2008; 213:137-44. [PMID: 18588876 DOI: 10.1016/j.expneurol.2008.05.017] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2008] [Revised: 05/09/2008] [Accepted: 05/16/2008] [Indexed: 01/28/2023]
Abstract
In clinically presymptomatic individuals with the Huntington's disease (HD) gene mutation, functional neuroimaging data have suggested a dysfunction of multiple cortical and subcortical regions including the prefrontal and parietal cortex, as well as the striatum. Although it has been hypothesized that these activation differences most likely reflect aberrant corticostriatal circuits, the functional coupling of neural networks associated with cognitive performance has not been investigated so far. In this study, we used functional magnetic resonance imaging (fMRI) and multivariate analytic techniques to investigate memory-related patterns of functional connectivity in healthy controls (n=16) and pre-HD individuals (n=16). Independent component analyses (ICA) revealed distinct bilateral frontostriatal and frontoparietal networks that were activated during a verbal working memory paradigm in both healthy controls and pre-HD subjects. Compared with healthy controls, pre-HD individuals exhibited lower functional connectivity in left lateral prefrontal and parietal regions as well as in the bilateral putamen. Functional connectivity indices in the left putamen were negatively correlated with the CAG repeat size and the UHDRS behavioral score, and positively correlated with the predicted years to manifest symptom onset. The connectivity of the right putamen was negatively correlated with the UHDRS motor score. In pre-HD individuals, these results suggest an early frontostriatal and frontoparietal deficit of dissociable functional networks associated with executive processing.
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Affiliation(s)
- Robert Christian Wolf
- Department of Psychiatry and Psychotherapy III, University of Ulm, Leimgrubenweg 12-14 89075 Ulm, Germany.
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23
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24
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Romero E, Cha GH, Verstreken P, Ly CV, Hughes RE, Bellen HJ, Botas J. Suppression of neurodegeneration and increased neurotransmission caused by expanded full-length huntingtin accumulating in the cytoplasm. Neuron 2008; 57:27-40. [PMID: 18184562 DOI: 10.1016/j.neuron.2007.11.025] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Revised: 06/21/2007] [Accepted: 11/06/2007] [Indexed: 11/26/2022]
Abstract
Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder caused by expansion of a translated CAG repeat in the N terminus of the huntingtin (htt) protein. Here we describe the generation and characterization of a full-length HD Drosophila model to reveal a previously unknown disease mechanism that occurs early in the course of pathogenesis, before expanded htt is imported into the nucleus in detectable amounts. We find that expanded full-length htt (128Qhtt(FL)) leads to behavioral, neurodegenerative, and electrophysiological phenotypes. These phenotypes are caused by a Ca2+-dependent increase in neurotransmitter release efficiency in 128Qhtt(FL) animals. Partial loss of function in synaptic transmission (syntaxin, Snap, Rop) and voltage-gated Ca2+ channel genes suppresses both the electrophysiological and the neurodegenerative phenotypes. Thus, our data indicate that increased neurotransmission is at the root of neuronal degeneration caused by expanded full-length htt during early stages of pathogenesis.
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Affiliation(s)
- Eliana Romero
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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25
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Kaltenbach LS, Romero E, Becklin RR, Chettier R, Bell R, Phansalkar A, Strand A, Torcassi C, Savage J, Hurlburt A, Cha GH, Ukani L, Chepanoske CL, Zhen Y, Sahasrabudhe S, Olson J, Kurschner C, Ellerby LM, Peltier JM, Botas J, Hughes RE. Huntingtin interacting proteins are genetic modifiers of neurodegeneration. PLoS Genet 2007; 3:e82. [PMID: 17500595 PMCID: PMC1866352 DOI: 10.1371/journal.pgen.0030082] [Citation(s) in RCA: 299] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Accepted: 04/06/2007] [Indexed: 12/25/2022] Open
Abstract
Huntington's disease (HD) is a fatal neurodegenerative condition caused by expansion of the polyglutamine tract in the huntingtin (Htt) protein. Neuronal toxicity in HD is thought to be, at least in part, a consequence of protein interactions involving mutant Htt. We therefore hypothesized that genetic modifiers of HD neurodegeneration should be enriched among Htt protein interactors. To test this idea, we identified a comprehensive set of Htt interactors using two complementary approaches: high-throughput yeast two-hybrid screening and affinity pull down followed by mass spectrometry. This effort led to the identification of 234 high-confidence Htt-associated proteins, 104 of which were found with the yeast method and 130 with the pull downs. We then tested an arbitrary set of 60 genes encoding interacting proteins for their ability to behave as genetic modifiers of neurodegeneration in a Drosophila model of HD. This high-content validation assay showed that 27 of 60 orthologs tested were high-confidence genetic modifiers, as modification was observed with more than one allele. The 45% hit rate for genetic modifiers seen among the interactors is an order of magnitude higher than the 1%–4% typically observed in unbiased genetic screens. Genetic modifiers were similarly represented among proteins discovered using yeast two-hybrid and pull-down/mass spectrometry methods, supporting the notion that these complementary technologies are equally useful in identifying biologically relevant proteins. Interacting proteins confirmed as modifiers of the neurodegeneration phenotype represent a diverse array of biological functions, including synaptic transmission, cytoskeletal organization, signal transduction, and transcription. Among the modifiers were 17 loss-of-function suppressors of neurodegeneration, which can be considered potential targets for therapeutic intervention. Finally, we show that seven interacting proteins from among 11 tested were able to co-immunoprecipitate with full-length Htt from mouse brain. These studies demonstrate that high-throughput screening for protein interactions combined with genetic validation in a model organism is a powerful approach for identifying novel candidate modifiers of polyglutamine toxicity. Huntington's Disease (HD) is a fatal inherited neurodegenerative disease, which typically begins in middle age and progresses with symptoms of severe uncontrolled movements and cognitive dysfunction. HD is uniformly fatal with death occurring ten to 15 years after onset of symptoms. There is currently no effective treatment for HD. The genetic mutation underlying HD causes a protein called huntingtin (Htt) to contain an abnormally long tract of the amino acid glutamine. This extended span of glutamines changes the shape of the Htt protein, which can cause it to interact in abnormal ways with other cellular proteins. In this study, we have identified a large number of new proteins that bind to normal and mutant forms of the Htt protein. To establish a potential role for these interacting proteins in HD, we show that changing the expression of many of these proteins can modulate the pathological effects of mutant Htt on fly neurons that deteriorate when they express mutant Htt. Identifying cellular proteins that bind to Htt and modulate its pathological activity may facilitate the discovery of an effective treatment for HD.
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Affiliation(s)
- Linda S Kaltenbach
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
| | - Eliana Romero
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Robert R Becklin
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
| | - Rakesh Chettier
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
| | - Russell Bell
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
| | - Amit Phansalkar
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
| | - Andrew Strand
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Cameron Torcassi
- Buck Institute for Age Research, Novato, California, United States of America
| | - Justin Savage
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
| | - Anthony Hurlburt
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
| | - Guang-Ho Cha
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lubna Ukani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | | | - Yuejun Zhen
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
| | | | - James Olson
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Cornelia Kurschner
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
| | - Lisa M Ellerby
- Buck Institute for Age Research, Novato, California, United States of America
| | - John M Peltier
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
| | - Juan Botas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- * To whom correspondence should be addressed. E-mail: (JB); (REH)
| | - Robert E Hughes
- Prolexys Pharmaceuticals, Salt Lake City, Utah, United States of America
- Buck Institute for Age Research, Novato, California, United States of America
- * To whom correspondence should be addressed. E-mail: (JB); (REH)
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26
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Oliveira JMA, Jekabsons MB, Chen S, Lin A, Rego AC, Gonçalves J, Ellerby LM, Nicholls DG. Mitochondrial dysfunction in Huntington's disease: the bioenergetics of isolated and in situ mitochondria from transgenic mice. J Neurochem 2007; 101:241-9. [PMID: 17394466 DOI: 10.1111/j.1471-4159.2006.04361.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Mitochondrial dysfunction is believed to participate in Huntington's disease (HD) pathogenesis. Here we compare the bioenergetic behavior of forebrain mitochondria isolated from different transgenic HD mice (R6/2, YAC128 and Hdh150 knock-in) and wild-type littermates with the first determination of in situ respiratory parameters in intact HD striatal neurons. We assess the Ca2+-loading capacity of isolated mitochondria by steady Ca2+-infusion. Mitochondria from R6/2 mice (12-13 weeks) and 12 months YAC128, but not homozygous or heterozygous Hdh150 knock-in mice (15-17 weeks), exhibit increased Ca2+-loading capacity when compared with respective wild-type littermates. In situ mitochondria in intact striatal neurons show high respiratory control. Moreover, moderate expression of full-length mutant huntingtin (in Hdh150 knock-in heterozygotes) does not significantly impair mitochondrial respiration in unstimulated neurons. However, when challenged with energy-demanding stimuli (NMDA-receptor activation in pyruvate-based media to accentuate the mitochondria role in Ca2+-handling), Hdh150 neurons are more vulnerable to Ca2+-deregulation than neurons from their wild-type littermates. These results stress the importance of assessing HD mitochondrial function in the cellular context.
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27
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Cepeda C, Wu N, André VM, Cummings DM, Levine MS. The corticostriatal pathway in Huntington's disease. Prog Neurobiol 2006; 81:253-71. [PMID: 17169479 PMCID: PMC1913635 DOI: 10.1016/j.pneurobio.2006.11.001] [Citation(s) in RCA: 233] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 10/08/2006] [Accepted: 11/03/2006] [Indexed: 11/21/2022]
Abstract
The corticostriatal pathway provides most of the excitatory glutamatergic input into the striatum and it plays an important role in the development of the phenotype of Huntington's disease (HD). This review summarizes results obtained from genetic HD mouse models concerning various alterations in this pathway. Evidence indicates that dysfunctions of striatal circuits and cortical neurons that make up the corticostriatal pathway occur during the development of the HD phenotype, well before there is significant neuronal cell loss. Morphological changes in the striatum are probably primed initially by alterations in the intrinsic functional properties of striatal medium-sized spiny neurons. Some of these alterations, including increased sensitivity of N-methyl-D-aspartate receptors in subpopulations of neurons, might be constitutively present but ultimately require abnormalities in the corticostriatal inputs for the phenotype to be expressed. Dysfunctions of the corticostriatal pathway are complex and there are multiple changes as demonstrated by significant age-related transient and more chronic interactions with the disease state. There also is growing evidence for changes in cortical microcircuits that interact to induce dysfunctions of the corticostriatal pathway. The conclusions of this review emphasize, first, the general role of neuronal circuits in the expression of the HD phenotype and, second, that both cortical and striatal circuits must be included in attempts to establish a framework for more rational therapeutic strategies in HD. Finally, as changes in cortical and striatal circuitry are complex and in some cases biphasic, therapeutic interventions should be regionally specific and take into account the temporal progression of the phenotype.
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Affiliation(s)
- Carlos Cepeda
- Mental Retardation Research Center, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA
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28
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Abstract
Huntington's disease (HD) is a devastating neurodegenerative disorder characterized by the progressive development of involuntary choreiform movements, cognitive impairment, neuropsychiatric symptoms, and premature death. These phenotypes reflect neuronal dysfunction and ultimately death in selected brain regions, the striatum and cerebral cortex being principal targets. The genetic mutation responsible for the HD phenotype is known, and its protein product, mutant huntingtin (mhtt), identified. HD is one of several "triplet repeat" diseases, in which abnormal expansions in trinucleotide repeat domains lead to elongated polyglutamine stretches in the affected gene's protein product. Mutant htt-mediated toxicity in the brain disrupts a number of vital cellular processes in the course of disease progression, including energy metabolism, gene transcription, clathrin-dependent endocytosis, intraneuronal trafficking, and postsynaptic signaling, but the crucial initiation mechanism induced by mhtt is still unclear. A large body of evidence, however, supports an early and critical involvement of defects in mitochondrial function and CNS energy metabolism in the disease trigger. Thus, downstream death-effector mechanisms, including excitotoxicity, apoptosis, and oxidative damage, have been implicated in the mechanism of selective neuronal damage in HD. Here we review the current evidence supporting a role for oxidative damage in the etiology of neuronal damage and degeneration in HD.
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Affiliation(s)
- Susan E Browne
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, New York, USA.
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Wang LH, Qin ZH. Animal models of Huntington's disease: implications in uncovering pathogenic mechanisms and developing therapies. Acta Pharmacol Sin 2006; 27:1287-302. [PMID: 17007735 DOI: 10.1111/j.1745-7254.2006.00410.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder, which is caused by an abnormal expansion of Cytosine Adenine Guanine (CAG) trinucleotide repeat in the gene making huntingtin (Htt). Despite intensive research efforts devoted to investigate molecular mechanisms of pathogenesis, effective therapy for this devastating disease is still not available at present. The development of various animal models of HD has offered alternative approaches in the study of HD molecular pathology. Many HD models, including chemical-induced models and genetic models, mimic some aspects of HD symptoms and pathology. To date, however, there is no ideal model which replicates all of the essential features of neuropathology and progressive motor and cognitive impairments of human HD. As a result, our understanding of molecular mechanisms of pathogenesis in HD is still limited. A new model is needed in order to uncover the pathogenesis and to develop novel therapies for HD. In this review we discussed usefulness and limitations of various animal and cellular models of HD in uncovering molecular mechanisms of pathogenesis and developing novel therapies for HD.
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Affiliation(s)
- Lin-hui Wang
- Department of Physiology, Soochow University School of Medicine, Suzhou 215123, China
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Abstract
Huntington's disease (HD) is a devastating neurodegenerative disease causing progressive movement disorders, cognitive dysfunction, and behavioral changes. Since the causative mutation of an expanded polyglutamine repeat in the huntingtin gene was identified, significant progress has been achieved in elucidating pathogenic mechanisms. This review summarizes recent developments in evaluating the role of abnormal protein aggregation, transcriptional dysregulation, mitochondrial and bioenergetic dysfunction, excitotoxicity, and abnormal cellular trafficking in the pathogenesis of HD. In addition, although therapeutic options in HD have been limited, progress in developing targeted therapies continues, and these advancements and future directions are reviewed.
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Wang W, Duan W, Igarashi S, Morita H, Nakamura M, Ross CA. Compounds blocking mutant huntingtin toxicity identified using a Huntington's disease neuronal cell model. Neurobiol Dis 2006; 20:500-8. [PMID: 15908226 DOI: 10.1016/j.nbd.2005.03.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2005] [Revised: 03/27/2005] [Accepted: 03/31/2005] [Indexed: 10/25/2022] Open
Abstract
Neuronal cell death in HD is believed to be largely a dominant cell-autonomous effect of the mutant huntingtin protein. We previously developed an inducible PC12 cell model which expresses an N-terminal huntingtin fragment with an expanded poly Q repeat (N63-148Q) under the control of the tet-off system. In order to evaluate the ability of compounds to protect against mutant huntingtin toxicity in our model, we measured LDH released by dead cells into the medium. We have now screened the library of 1040 compounds from the NINDS Custom Collection as part of a National Institute of Neurological Disorders and Stroke (NINDS) collaborative project. Each positive compound was tested at 3-8 concentrations. Five compounds significantly attenuated mutant huntingtin (htt)-induced LDH release without affecting the expression level of huntingtin and independent of effect on aggregates. We also tested a broad spectrum caspase inhibitor Z-VAD-fmk and previously proposed candidate compounds. This cell model can provide a method to screen potential therapeutic compounds for treating Huntington's disease.
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Affiliation(s)
- Wenfei Wang
- Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2109, USA
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32
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Abstract
Huntington's disease is an autosomal dominant neurodegenerative disorder that is characterized by motor, cognitive, and psychiatric alterations. The mutation responsible for this fatal disease is an abnormally expanded and unstable CAG repeat within the coding region of the gene encoding huntingtin. Numerous mouse models have been generated that constitute invaluable tools to examine the pathogenesis of the disease and to develop and evaluate novel therapies. Among those models, knock-in mice provide a genetically precise reproduction of the human condition. The slow progression and early development of behavioral, pathological, cellular, and molecular abnormalities in knock-in mice make these animals valuable to understand the early pathological events triggered by the mutation. This review describes the different knock-in models generated, the insight gained from them, and their value in the development and testing of prospective treatments of the disease.
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Oliveira AMM, Abel T, Brindle PK, Wood MA. Differential role for CBP and p300 CREB-binding domain in motor skill learning. Behav Neurosci 2006; 120:724-9. [PMID: 16768624 DOI: 10.1037/0735-7044.120.3.724] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cyclic adenosine monophosphate response element binding protein (CREB) binding protein (CBP) and E1A binding protein (p300) are highly homologous transcriptional coactivators with histone acetyltransferase activity. Although CBP and p300 have unique functions in vivo during embryogenesis and hematopoiesis, their functions within the nervous system remain poorly understood. The authors demonstrate that these coactivators have differential roles in motor skill learning. Mice with a mutation in the CREB-binding (KIX) domain of CBP exhibited motor learning deficits. However, mice with the analogous mutation in the KIX domain of p300 showed normal motor learning. Further, CREB knock-out mice exhibited a motor learning deficit similar to that of CBP-KIX mutant mice. These results suggest that the CREB-CBP interaction is more limiting or critical than the CREB-p300 interaction for motor skill learning. Thus, CBP and p300 are genetically distinct at the behavioral level.
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Affiliation(s)
- Ana M M Oliveira
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
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Jeong SJ, Kim M, Chang KA, Kim HS, Park CH, Suh YH. Huntingtin is localized in the nucleus during preimplanatation embryo development in mice. Int J Dev Neurosci 2005; 24:81-5. [PMID: 16289942 DOI: 10.1016/j.ijdevneu.2005.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 09/16/2005] [Accepted: 10/03/2005] [Indexed: 11/25/2022] Open
Abstract
Huntington's disease (HD) is a dominant neurodegenerative disorder caused by the expansion of a CAG repeat in the gene encoding huntingtin. Moreover, the nuclear targeting of mutant huntingtin increases cellular toxicity, whereas normal huntingtin resides mainly in the cytoplasm, and is associated with membranes or microtubules. Huntingtin is enriched in neurons and its expression is increased during neural development. The inactivation of the HD gene results in embryonic lethality before nervous system development. Thus, huntingtin is critical during early embryonic development. Nevertheless, the function of huntingtin at this stage is unknown, even the distribution of the protein has not been described. The present study was undertaken to elucidate the distribution of huntingtin during the early developmental period in the mouse embryo. At the preimplantation stage, huntingtin was detected in nuclei up to 2.5 days post coitum (dpc), but disappeared from nuclei during the blastocyst stage (3.5 dpc). Following this stage, huntingtin was mainly localized in the cytoplasm and co-localized with mitotic spindles. These data suggest that the nuclear targeting of normal huntingtin is required during early embryo development in mice.
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Affiliation(s)
- Sung-Jin Jeong
- Department of Pharmacology, College of Medicine, Seoul National University, Neuroscience Research Institute of SNUMRC, 28 Yongon-Dong, Chongro-Gu, Seoul 110-744, South Korea
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Abstract
The Huntington disease gene was mapped to human chromosome 4p in 1983 and 10 years later the pathogenic mutation was identified as a CAG-repeat expansion. Our current understanding of the molecular pathogenesis of Huntington disease could never have been achieved without the recent progress in the field of molecular genetics. We are now equipped with powerful genetic models that continue to uncover new aspects of the pathogenesis of Huntington disease and will be instrumental for the development of therapeutic approaches for this disease.
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Affiliation(s)
- Gillian P Bates
- Department of Medical and Molecular Genetics, GKT School of Medicine, King's College London, 8th Floor Guy's Tower, Guy's Hospital, London SE1 9RT, United Kingdom.
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Canals JM, Pineda JR, Torres-Peraza JF, Bosch M, Martín-Ibañez R, Muñoz MT, Mengod G, Ernfors P, Alberch J. Brain-derived neurotrophic factor regulates the onset and severity of motor dysfunction associated with enkephalinergic neuronal degeneration in Huntington's disease. J Neurosci 2005; 24:7727-39. [PMID: 15342740 PMCID: PMC6729627 DOI: 10.1523/jneurosci.1197-04.2004] [Citation(s) in RCA: 265] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The mechanism that controls the selective vulnerability of striatal neurons in Huntington's disease is unclear. Brain-derived neurotrophic factor (BDNF) protects striatal neurons and is regulated by Huntingtin through the interaction with the neuron-restrictive silencer factor. Here, we demonstrate that the downregulation of BDNF by mutant Huntingtin depends on the length and levels of expression of the CAG repeats in cell cultures. To analyze the functional effects of these changes in BDNF in Huntington's disease, we disrupted the expression of bdnf in a transgenic mouse model by cross-mating bdnf(+/ -) mice with R6/1 mice. Thus, we compared transgenic mice for mutant Huntingtin with different levels of BDNF. Using this double mutant mouse line, we show that the deficit of endogenous BDNF modulates the pathology of Huntington's disease. The decreased levels of this neurotrophin advance the onset of motor dysfunctions and produce more severe uncoordinated movements. This behavioral pathology correlates with the loss of striatal dopamine and cAMP-regulated phosphoprotein-32-positive projection neurons. In particular, the insufficient levels of BDNF cause specific degeneration of the enkephalinergic striatal projection neurons, which are the most affected cells in Huntington's disease. This neuronal dysfunction can specifically be restored by administration of exogenous BDNF. Therefore, the decrease in BDNF levels plays a key role in the specific pathology observed in Huntington's disease by inducing dysfunction of striatal enkephalinergic neurons that produce severe motor dysfunctions. Hence, administration of exogenous BDNF may delay or stop illness progression.
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Affiliation(s)
- Josep M Canals
- Departament de Biologia Cel.lular i Anatomia Patològica, Facultat de Medicina, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Universitat de Barcelona, Spain
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Ribchester RR, Thomson D, Wood NI, Hinks T, Gillingwater TH, Wishart TM, Court FA, Morton AJ. Progressive abnormalities in skeletal muscle and neuromuscular junctions of transgenic mice expressing the Huntington's disease mutation. Eur J Neurosci 2004; 20:3092-114. [PMID: 15579164 DOI: 10.1111/j.1460-9568.2004.03783.x] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Huntington's disease (HD) is a neurodegenerative disorder with complex symptoms dominated by progressive motor dysfunction. Skeletal muscle atrophy is common in HD patients. Because the HD mutation is expressed in skeletal muscle as well as brain, we wondered whether the muscle changes arise from primary pathology. We used R6/2 transgenic mice for our studies. Unlike denervation atrophy, skeletal muscle atrophy in R6/2 mice occurs uniformly. Paradoxically however, skeletal muscles show age-dependent denervation-like abnormalities, including supersensitivity to acetylcholine, decreased sensitivity to mu-conotoxin, and anode-break action potentials. Morphological abnormalities of neuromuscular junctions are also present, particularly in older R6/2 mice. Severely affected R6/2 mice show a progressive increase in the number of motor endplates that fail to respond to nerve stimulation. Surprisingly, there was no constitutive sprouting of motor neurons in R6/2 muscles, even in severely atrophic muscles that showed other denervation-like characteristics. In fact, there was an age-dependent loss of regenerative capacity of motor neurons in R6/2 mice. Because muscle fibers appear to be released from the activity-dependent cues that regulate membrane properties and muscle size, and motor axons and nerve terminals become impaired in their capacity to release neurotransmitter and to respond to stimuli that normally evoke sprouting and adaptive reinnervation, we speculate that in these mice there is a progressive dissociation of trophic signalling between motor neurons and skeletal muscle. However, irrespective of the cause, the abnormalities at neuromuscular junctions we report here are likely to contribute to the pathological phenotype in R6/2 mice, particularly in late stages of the disease.
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Affiliation(s)
- Richard R Ribchester
- Division of Neuroscience, University of Edinburgh, George Square, Edinburgh EH8 9JZ, UK
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Levine MS, Cepeda C, Hickey MA, Fleming SM, Chesselet MF. Genetic mouse models of Huntington's and Parkinson's diseases: illuminating but imperfect. Trends Neurosci 2004; 27:691-7. [PMID: 15474170 DOI: 10.1016/j.tins.2004.08.008] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Genetic mouse models based on identification of genes that cause Huntington's and Parkinson's diseases have revolutionized understanding of the mechanistic pathophysiological progression of these disorders. These models allow the earliest manifestations of the diseases to be identified, and they display behavioral, neuropathological and electrophysiological deficits that can be followed over time in mechanistic and drug studies. An intriguing feature is that they do not reproduce the relatively selective and massive cell loss characterizing the human diseases. There is more information on Huntington's disease models because the disorder involves a single gene that was identified over ten years ago; genetic mutations causing Parkinson's disease are rare and were discovered more recently, and models of the disease have been generated only within the past few years.
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Affiliation(s)
- Michael S Levine
- Mental Retardation Research Center, The David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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Affiliation(s)
- Francis O Walker
- Department of Neurology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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