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Wang Y, Ramandi D, Sepers MD, Mackay JP, Raymond LA. Age- and region-dependent cortical excitability in the zQ175 Huntington disease mouse model. Hum Mol Genet 2024; 33:387-399. [PMID: 37947186 PMCID: PMC10877458 DOI: 10.1093/hmg/ddad191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 09/29/2023] [Accepted: 11/02/2023] [Indexed: 11/12/2023] Open
Abstract
The neurodegenerative disorder, Huntington disease (HD), manifests as disorders of movement, cognition and mood. Although studies report abnormal corticostriatal synaptic function early in HD mouse models, less is known about cortical-cortical activity across brain regions and disease stages. Recently, we reported enhanced mesoscale spread of cortical responses to sensory stimulation in vivo at early-manifest stages of two HD mouse models. Here, we investigated cortical excitability of zQ175 HD-model mice compared to their wild-type littermates across different cell types, ages and/or cortical regions using ex vivo electrophysiology. Cortical pyramidal neurons (CPNs) in somatosensory cortex of zQ175 mice showed intrinsic hyper-excitability at 3-4 months, but hypo-excitability at early-manifest stage (8-9 months); reduced frequency of spontaneous excitatory postsynaptic currents (sEPSCs) was seen at both ages. In contrast, motor cortex CPNs in early-manifest zQ175 mice showed increased intrinsic excitability and sEPSC frequency. Large-amplitude excitatory discharges recorded from CPNs in early-manifest zQ175 mice showed increased frequency only in somatosensory cortex, suggesting the intrinsic hypo-excitability of these CPNs may be compensatory against cortical network hyper-excitability. Similarly, in early-manifest zQ175 mice, region-dependent differences were seen in fast-spiking interneurons (FSIs): somatosensory but not motor FSIs from early-manifest zQ175 mice had reduced intrinsic excitability. Moreover, CPNs showed decreased frequency of spontaneous inhibitory postsynaptic currents and increased excitatory-inhibitory (E-I) balance of evoked synaptic currents in somatosensory cortex. Aberrant large-amplitude discharges and reduced inhibitory drive may therefore underlie E-I imbalances that result in circuit changes and synaptic dysfunction in early-manifest HD.
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Affiliation(s)
- Yundi Wang
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
| | - Daniel Ramandi
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
- Graduate Program in Cell and Developmental Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 2A1, Canada
| | - Marja D Sepers
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
| | - James P Mackay
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
| | - Lynn A Raymond
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
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McColgan P, Gregory S, Zeun P, Zarkali A, Johnson EB, Parker C, Fayer K, Lowe J, Nair A, Estevez-Fraga C, Papoutsi M, Zhang H, Scahill RI, Tabrizi SJ, Rees G. Neurofilament light-associated connectivity in young-adult Huntington's disease is related to neuronal genes. Brain 2022; 145:3953-3967. [PMID: 35758263 PMCID: PMC9679168 DOI: 10.1093/brain/awac227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 05/27/2022] [Accepted: 06/03/2022] [Indexed: 11/13/2022] Open
Abstract
Upregulation of functional network connectivity in the presence of structural degeneration is seen in the premanifest stages of Huntington's disease (preHD) 10-15 years from clinical diagnosis. However, whether widespread network connectivity changes are seen in gene carriers much further from onset has yet to be explored. We characterized functional network connectivity throughout the brain and related it to a measure of disease pathology burden (CSF neurofilament light, NfL) and measures of structural connectivity in asymptomatic gene carriers, on average 24 years from onset. We related these measurements to estimates of cortical and subcortical gene expression. We found no overall differences in functional (or structural) connectivity anywhere in the brain comparing control and preHD participants. However, increased functional connectivity, particularly between posterior cortical areas, correlated with increasing CSF NfL level in preHD participants. Using the Allen Human Brain Atlas and expression-weighted cell-type enrichment analysis, we demonstrated that this functional connectivity upregulation occurred in cortical regions associated with regional expression of genes specific to neuronal cells. This relationship was validated using single-nucleus RNAseq data from post-mortem Huntington's disease and control brains showing enrichment of neuronal-specific genes that are differentially expressed in Huntington's disease. Functional brain networks in asymptomatic preHD gene carriers very far from disease onset show evidence of upregulated connectivity correlating with increased disease burden. These changes occur among brain areas that show regional expression of genes specific to neuronal GABAergic and glutamatergic cells.
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Affiliation(s)
- Peter McColgan
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Sarah Gregory
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Paul Zeun
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Angeliki Zarkali
- Dementia Research Centre, University College London, London WC1N 3AR, UK
| | - Eileanoir B Johnson
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Christopher Parker
- Department of Computer Science and Centre for Medical Image Computing, University College London, London WC1V 6LJ, UK
| | - Kate Fayer
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Jessica Lowe
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Akshay Nair
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- Max Planck University College London Centre for Computational Psychiatry and Ageing Research, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Carlos Estevez-Fraga
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Marina Papoutsi
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Hui Zhang
- Dementia Research Centre, University College London, London WC1N 3AR, UK
| | - Rachael I Scahill
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Sarah J Tabrizi
- Huntington’s Disease Centre, Department of Neurodegenerative disease, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- Dementia Research Centre, University College London, London WC1N 3AR, UK
| | - Geraint Rees
- University College London Institute of Cognitive Neuroscience, University College London, London WC1N 3AZ, UK
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3
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Voelkl K, Schulz-Trieglaff EK, Klein R, Dudanova I. Distinct histological alterations of cortical interneuron types in mouse models of Huntington’s disease. Front Neurosci 2022; 16:1022251. [PMID: 36225731 PMCID: PMC9549412 DOI: 10.3389/fnins.2022.1022251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 09/07/2022] [Indexed: 11/25/2022] Open
Abstract
Huntington’s disease (HD) is a debilitating hereditary motor disorder caused by an expansion of the CAG triplet repeat in the Huntingtin gene. HD causes neurodegeneration particularly in the basal ganglia and neocortex. In the cortex, glutamatergic pyramidal neurons are known to be severely affected by the disease, but the involvement of GABAergic interneurons remains unclear. Here, we use a combination of immunostaining and genetic tracing to investigate histological changes in three major cortical interneuron types — parvalbumin (PV), somatostatin (SST), and vasoactive intestinal peptide (VIP) interneurons — in the R6/2 and zQ175DN mouse models of HD. In R6/2 mice, we find a selective reduction in SST and VIP, but not PV-positive cells. However, genetic labeling reveals unchanged cell numbers for all the interneuron types, pointing to molecular marker loss in the absence of cell death. We also observe a reduction in cell body size for all three interneuron populations. Furthermore, we demonstrate progressive accumulation of mutant Huntingtin (mHTT) inclusion bodies in interneurons, which occurs faster in SST and VIP compared to PV cells. In contrast to the R6/2 model, heterozygous zQ175DN knock-in HD mice do not show any significant histological changes in cortical cell types at the age of 12 months, apart from the presence of mHTT inclusions, which are abundant in pyramidal neurons and rare in interneurons. Taken together, our findings point to differential molecular changes in cortical interneuron types of HD mice.
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Affiliation(s)
- Kerstin Voelkl
- Department of Molecules–Signaling–Development, Max Planck Institute for Biological Intelligence, Martinsried, Germany
- Molecular Neurodegeneration Group, Max Planck Institute for Biological Intelligence, Martinsried, Germany
| | | | - Rüdiger Klein
- Department of Molecules–Signaling–Development, Max Planck Institute for Biological Intelligence, Martinsried, Germany
| | - Irina Dudanova
- Department of Molecules–Signaling–Development, Max Planck Institute for Biological Intelligence, Martinsried, Germany
- Molecular Neurodegeneration Group, Max Planck Institute for Biological Intelligence, Martinsried, Germany
- Center for Anatomy, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
- *Correspondence: Irina Dudanova,
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4
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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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5
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Kaye J, Reisine T, Finkbeiner S. Huntington's disease mouse models: unraveling the pathology caused by CAG repeat expansion. Fac Rev 2021; 10:77. [PMID: 34746930 PMCID: PMC8546598 DOI: 10.12703/r/10-77] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disease that results in motor and cognitive dysfunction, leading to early death. HD is caused by an expansion of CAG repeats in the huntingtin gene (HTT). Here, we review the mouse models of HD. They have been used extensively to better understand the molecular and cellular basis of disease pathogenesis as well as to provide non-human subjects to test the efficacy of potential therapeutics. The first and best-studied in vivo rodent model of HD is the R6/2 mouse, in which a transgene containing the promoter and exon 1 fragment of human HTT with 150 CAG repeats was inserted into the mouse genome. R6/2 mice express rapid, robust behavioral pathologies and display a number of degenerative abnormalities in neuronal populations most vulnerable in HD. The first conditional full-length mutant huntingtin (mHTT) mouse model of HD was the bacterial artificial chromosome (BAC) transgenic mouse model of HD (BACHD), which expresses human full-length mHTT with a mixture of 97 CAG-CAA repeats under the control of endogenous HTT regulatory machinery. It has been useful in identifying the role of mHTT in specific neuronal populations in degenerative processes. In the knock-in (KI) model of HD, the expanded human CAG repeats and human exon 1 are inserted into the mouse Htt locus, so a chimera of the full-length mouse protein with the N-terminal human portion is expressed. Many of aspects of the pathology and behavioral deficits in the KI model better mimic disease characteristics found in HD patients than other models. Accordingly, some have proposed that these mice may be preferable models of the disease over others. Indeed, as our understanding of HD advances, so will the design of animal models to test and develop HD therapies.
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Affiliation(s)
- Julia Kaye
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
| | - Terry Reisine
- Independent Scientific Consultant, Santa Cruz, CA, USA
| | - Steve Finkbeiner
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
- Taube/Koret Center for Neurodegenerative Disease Research, Gladstone Institutes, San Francisco, CA, USA
- Department of Neurology and Physiology, University of California, San Francisco, CA, USA
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6
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Shobe JL, Donzis EJ, Lee K, Chopra S, Masmanidis SC, Cepeda C, Levine MS. Early impairment of thalamocortical circuit activity and coherence in a mouse model of Huntington's disease. Neurobiol Dis 2021; 157:105447. [PMID: 34274461 PMCID: PMC8591983 DOI: 10.1016/j.nbd.2021.105447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 06/22/2021] [Accepted: 07/13/2021] [Indexed: 10/20/2022] Open
Abstract
Huntington's disease (HD) is a progressive, fatal neurodegenerative disorder characterized by motor, cognitive, and psychiatric disturbances. There is no known cure for HD, but its progressive nature allows for early therapeutic intervention. Currently, much of the research has focused on the striatum, however, there is evidence suggesting that disruption of thalamocortical circuits could underlie some of the early symptoms of HD. Loss of both cortical pyramidal neurons (CPNs) and thalamic neurons occurs in HD patients, and cognitive, somatosensory, and attention deficits precede motor abnormalities. However, the role of thalamocortical pathways in HD progression has been understudied. Here, we measured single unit activity and local field potentials (LFPs) from electrode arrays implanted in the thalamus and primary motor cortex of 4-5 month-old male and female Q175 mice. We assessed neuronal activity under baseline conditions as well as during presentation of rewards delivered via actuation of an audible solenoid valve. HD mice showed a significantly delayed licking response to the reward stimulus. At the same time, neuronal activation to the reward was delayed in thalamic neurons, CPNs and fast-spiking cortical interneurons (FSIs) of HD mice. In addition, thalamocortical coherence increased at lower frequencies in HD relative to wildtype mice. Together, these data provide evidence that impaired cortical and thalamic responses to reward stimuli, and impaired thalamocortical coherence, may play an important early role in motor, cognitive, and learning deficits in HD patients.
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Affiliation(s)
- Justin L Shobe
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA
| | - Elissa J Donzis
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, CA, USA
| | - Kwang Lee
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, South Korea
| | - Samiksha Chopra
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, CA, USA
| | - Sotiris C Masmanidis
- Department of Neurobiology, University of California Los Angeles, Los Angeles, CA, USA
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, CA, USA
| | - Michael S Levine
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, CA, USA.
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7
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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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8
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Cheong RY, Baldo B, Sajjad MU, Kirik D, Petersén Å. Effects of mutant huntingtin inactivation on Huntington disease-related behaviours in the BACHD mouse model. Neuropathol Appl Neurobiol 2021; 47:564-578. [PMID: 33330988 PMCID: PMC8247873 DOI: 10.1111/nan.12682] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/27/2020] [Accepted: 12/14/2020] [Indexed: 01/02/2023]
Abstract
AIMS Huntington disease (HD) is a fatal neurodegenerative disorder with no disease-modifying treatments approved so far. Ongoing clinical trials are attempting to reduce huntingtin (HTT) expression in the central nervous system (CNS) using different strategies. Yet, the distribution and timing of HTT-lowering therapies required for a beneficial clinical effect is less clear. Here, we investigated whether HD-related behaviours could be prevented by inactivating mutant HTT at different disease stages and to varying degrees in an experimental model. METHODS We generated mutant BACHD mice with either a widespread or circuit-specific inactivation of mutant HTT by using Cre recombinase (Cre) under the nestin promoter or the adenosine A2A receptor promoter respectively. We also simulated a clinical gene therapy scenario with allele-specific HTT targeting by injections of recombinant adeno-associated viral (rAAV) vectors expressing Cre into the striatum of adult BACHD mice. All mice were assessed using behavioural tests to investigate motor, metabolic and psychiatric outcome measures at 4-6 months of age. RESULTS While motor deficits, body weight changes, anxiety and depressive-like behaviours are present in BACHD mice, early widespread CNS inactivation during development significantly improves rotarod performance, body weight changes and depressive-like behaviour. However, conditional circuit-wide mutant HTT deletion from the indirect striatal pathway during development and focal striatal-specific deletion in adulthood failed to rescue any of the HD-related behaviours. CONCLUSIONS Our results indicate that widespread targeting and the timing of interventions aimed at reducing mutant HTT are important factors to consider when developing disease-modifying therapies for HD.
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Affiliation(s)
- Rachel Y. Cheong
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Barbara Baldo
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
- Present address:
Evotec SEHD Research and Translational SciencesHamburgGermany
| | - Muhammad U. Sajjad
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Deniz Kirik
- Brain Repair and Imaging in Neural Systems UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Åsa Petersén
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
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9
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Cepeda C, Levine MS. Synaptic Dysfunction in Huntington's Disease: Lessons from Genetic Animal Models. Neuroscientist 2020; 28:20-40. [PMID: 33198566 DOI: 10.1177/1073858420972662] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The understanding of the functional and structural changes occurring in the cerebral cortex and basal ganglia in Huntington's disease (HD) has benefited considerably from the generation of genetic animal models. Most studies of synaptic alterations in HD models have focused on the striatum, but a more complete picture of synaptic dysfunction in the cortico-basal ganglia-cortical loop is emerging. Here, we provide a review and analysis of current developments in the study of synaptic alterations in these areas using HD rodent models. Recent evidence indicates that cortical maldevelopment plays a role in synaptic dysfunction along the corticostriatal pathway that may have its roots in the way mutant huntingtin interacts with synaptic proteins. Furthermore, a progressive disconnection in the corticostriatal pathway leads to abnormal function engaging extrasynaptic N-methyl-D-aspartate glutamate receptors that contribute to eventual cell degeneration. In addition, biphasic increases followed by decreases in glutamate and dopamine release in the striatum could explain contrasting symptomatology in early and late stages of the disease. Changes in striatal output regions also are beginning to be examined. Finally, we highlight some therapeutic avenues aimed at rescuing synaptic dysfunction.
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Affiliation(s)
- Carlos Cepeda
- IDDRC, Jane and Terry Semel Institute for Neuroscience & Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Michael S Levine
- IDDRC, Jane and Terry Semel Institute for Neuroscience & Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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10
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McColgan P, Joubert J, Tabrizi SJ, Rees G. The human motor cortex microcircuit: insights for neurodegenerative disease. Nat Rev Neurosci 2020; 21:401-415. [PMID: 32555340 DOI: 10.1038/s41583-020-0315-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2020] [Indexed: 12/22/2022]
Abstract
The human motor cortex comprises a microcircuit of five interconnected layers with different cell types. In this Review, we use a layer-specific and cell-specific approach to integrate physiological accounts of this motor cortex microcircuit with the pathophysiology of neurodegenerative diseases affecting motor functions. In doing so we can begin to link motor microcircuit pathology to specific disease stages and clinical phenotypes. Based on microcircuit physiology, we can make future predictions of axonal loss and microcircuit dysfunction. With recent advances in high-resolution neuroimaging we can then test these predictions in humans in vivo, providing mechanistic insights into neurodegenerative disease.
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Affiliation(s)
- Peter McColgan
- Huntington's Disease Research Centre, UCL Institute of Neurology, University College London, London, UK.
| | - Julie Joubert
- Huntington's Disease Research Centre, UCL Institute of Neurology, University College London, London, UK
| | - Sarah J Tabrizi
- Huntington's Disease Research Centre, UCL Institute of Neurology, University College London, London, UK.,Dementia Research Institute at UCL, London, UK
| | - Geraint Rees
- Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, University College London, London, UK.,UCL Institute of Cognitive Neuroscience, University College London, London, UK
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11
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Blumenstock S, Dudanova I. Cortical and Striatal Circuits in Huntington's Disease. Front Neurosci 2020; 14:82. [PMID: 32116525 PMCID: PMC7025546 DOI: 10.3389/fnins.2020.00082] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/21/2020] [Indexed: 12/28/2022] Open
Abstract
Huntington's disease (HD) is a hereditary neurodegenerative disorder that typically manifests in midlife with motor, cognitive, and/or psychiatric symptoms. The disease is caused by a CAG triplet expansion in exon 1 of the huntingtin gene and leads to a severe neurodegeneration in the striatum and cortex. Classical electrophysiological studies in genetic HD mouse models provided important insights into the disbalance of excitatory, inhibitory and neuromodulatory inputs, as well as progressive disconnection between the cortex and striatum. However, the involvement of local cortical and striatal microcircuits still remains largely unexplored. Here we review the progress in understanding HD-related impairments in the cortical and basal ganglia circuits, and outline new opportunities that have opened with the development of modern circuit analysis methods. In particular, in vivo imaging studies in mouse HD models have demonstrated early structural and functional disturbances within the cortical network, and optogenetic manipulations of striatal cell types have started uncovering the causal roles of certain neuronal populations in disease pathogenesis. In addition, the important contribution of astrocytes to HD-related circuit defects has recently been recognized. In parallel, unbiased systems biology studies are providing insights into the possible molecular underpinnings of these functional defects at the level of synaptic signaling and neurotransmitter metabolism. With these approaches, we can now reach a deeper understanding of circuit-based HD mechanisms, which will be crucial for the development of effective and targeted therapeutic strategies.
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Affiliation(s)
- Sonja Blumenstock
- Department of Molecules – Signaling – Development, Max Planck Institute of Neurobiology, Martinsried, Germany
- Molecular Neurodegeneration Group, Max Planck Institute of Neurobiology, Martinsried, Germany
| | - Irina Dudanova
- Molecular Neurodegeneration Group, Max Planck Institute of Neurobiology, Martinsried, Germany
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12
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Cepeda C, Oikonomou KD, Cummings D, Barry J, Yazon VW, Chen DT, Asai J, Williams CK, Vinters HV. Developmental origins of cortical hyperexcitability in Huntington's disease: Review and new observations. J Neurosci Res 2019; 97:1624-1635. [PMID: 31353533 PMCID: PMC6801077 DOI: 10.1002/jnr.24503] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 12/13/2022]
Abstract
Huntington's disease (HD), an inherited neurodegenerative disorder that principally affects striatum and cerebral cortex, is generally thought to have an adult onset. However, a small percentage of cases develop symptoms before 20 years of age. This juvenile variant suggests that brain development may be altered in HD. Indeed, recent evidence supports an important role of normal huntingtin during embryonic brain development and mutations in this protein cause cortical abnormalities. Functional studies also demonstrated that the cerebral cortex becomes hyperexcitable with disease progression. In this review, we examine clinical and experimental evidence that cortical development is altered in HD. We also provide preliminary evidence that cortical pyramidal neurons from R6/2 mice, a model of juvenile HD, are hyperexcitable and display dysmorphic processes as early as postnatal day 7. Further, some symptomatic mice present with anatomical abnormalities reminiscent of human focal cortical dysplasia, which could explain the occurrence of epileptic seizures in this genetic mouse model and in children with juvenile HD. Finally, we discuss recent treatments aimed at correcting abnormal brain development.
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Affiliation(s)
- Carlos Cepeda
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Katerina D. Oikonomou
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Damian Cummings
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Joshua Barry
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Vannah-Wila Yazon
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Dickson T. Chen
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Janelle Asai
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Christopher K. Williams
- Section of Neuropathology, Department of Pathology and Laboratory Medicine and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Harry V. Vinters
- Section of Neuropathology, Department of Pathology and Laboratory Medicine and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
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13
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Γ-Aminobutyric acid in adult brain: an update. Behav Brain Res 2019; 376:112224. [DOI: 10.1016/j.bbr.2019.112224] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 09/09/2019] [Accepted: 09/09/2019] [Indexed: 01/21/2023]
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14
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Estrada-Sánchez AM, Blake CL, Barton SJ, Howe AG, Rebec GV. Lack of mutant huntingtin in cortical efferents improves behavioral inflexibility and corticostriatal dynamics in Huntington's disease mice. J Neurophysiol 2019; 122:2621-2629. [PMID: 31693428 DOI: 10.1152/jn.00777.2018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Abnormal communication between cerebral cortex and striatum plays a major role in the motor symptoms of Huntington's disease (HD), a neurodegenerative disorder caused by a mutation of the huntingtin gene (mHTT). Because cortex is the main driver of striatal processing, we recorded local field potential (LFP) activity simultaneously in primary motor cortex (M1) and dorsal striatum (DS) in BACHD mice, a full-length HD gene model, and in a conditional BACHD/Emx-1 Cre (BE) model in which mHTT is suppressed in cortical efferents, while mice freely explored a plus-shaped maze beginning at 20 wk of age. Relative to wild-type (WT) controls, BACHD mice were just as active across >40 wk of testing but became progressively less likely to turn into a perpendicular arm as they approached the choice point of the maze, a sign of HD motor inflexibility. BE mice, in contrast, turned as freely as WT throughout testing. Although BE mice did not exactly match WT in LFP activity, the reduction in alpha (8-13 Hz), beta (13-30 Hz), and low-gamma (30-50 Hz) power that occurred in M1 of turning-impaired BACHD mice was reversed. No reversal occurred in DS. In fact, BE mice showed further reductions in DS theta (4-8 Hz), beta, and low-gamma power relative to the BACHD model. Coherence analysis indicated a dysregulation of corticostriatal information flow in both BACHD and BE mice. Collectively, our results suggest that mHTT in cortical outputs drives the dysregulation of select cortical frequencies that accompany the loss of behavioral flexibility in HD.NEW & NOTEWORTHY BACHD mice, a full-length genetic model of Huntington's disease (HD), express aberrant local field potential (LFP) activity in primary motor cortex (M1) along with decreased probability of turning into a perpendicular arm of a plus-shaped maze, a motor inflexibility phenotype. Suppression of the mutant huntingtin gene in cortical output neurons prevents decline in turning and improves alpha, beta, and low-gamma activity in M1. Our results implicate cortical networks in the search for therapeutic strategies to alleviate HD motor signs.
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Affiliation(s)
- Ana María Estrada-Sánchez
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana.,Departmento de Biología Molecular, Instituto Potosino De Investigación Científica y Tecnológica, San Luis Potosí, Mexico
| | - Courtney L Blake
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana
| | - Scott J Barton
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana
| | - Andrew G Howe
- Neuroscience Interdepartmental Program, University of California, Los Angeles, California.,Department of Psychology, University of California, Los Angeles, California
| | - George V Rebec
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana
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15
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Sex-dependent impaired locomotion and motor coordination in the HdhQ200/200 mouse model of Huntington's Disease. Neurobiol Dis 2019; 132:104607. [PMID: 31499139 DOI: 10.1016/j.nbd.2019.104607] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 08/02/2019] [Accepted: 09/04/2019] [Indexed: 01/08/2023] Open
Abstract
Huntington's Disease (HD) is a fatal neurodegenerative disease characterized by severe loss of medium spiny neuron (MSN) function and striatal-dependent behaviors. We report that female HdhQ200/200 mice display an earlier onset and more robust deterioration in spontaneous locomotion and motor coordination measured at 8 months of age compared to male HdhQ200/200 mice. Remarkably, HdhQ200/200 mice of both sexes exhibit comparable impaired spontaneous locomotion and motor coordination at 10 months of age and reach moribund stage by 12 months of age, demonstrating reduced life span in this model system. Histopathological analysis revealed enhanced mutant huntingtin protein aggregation in male HdhQ200/200 striatal tissue at 8 months of age compared to female HdhQ200/200. Functional analysis of calcium dynamics in MSNs of female HdhQ200/200 mice using GCaMP6m imaging revealed elevated responses to excitatory cortical-striatal stimulation suggesting increased MSN excitability. Although there was no down-regulation of the expression of common HD biomarkers (DARPP-32, enkephalin and CB1R), we measured a sex-dependent reduction of the astrocytic glutamate transporter, GLT-1, in female HdhQ200/200 mice that was not detected in male HdhQ200/200 mice when compared to respective wild-type littermates. Our study outlines a sex-dependent rapid deterioration of striatal-dependent behaviors occurring in the HdhQ200/200 mouse line that does not involve alterations in the expression of common HD biomarkers and yet includes impaired MSN function.
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16
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Marottoli FM, Priego M, Flores-Barrera E, Pisharody R, Zaldua S, Fan KD, Ekkurthi GK, Brady ST, Morfini GA, Tseng KY, Tai LM. EGF Treatment Improves Motor Behavior and Cortical GABAergic Function in the R6/2 Mouse Model of Huntington's Disease. Mol Neurobiol 2019; 56:7708-7718. [PMID: 31104296 DOI: 10.1007/s12035-019-1634-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 04/24/2019] [Indexed: 01/13/2023]
Abstract
Recent evidence indicates that disruption of epidermal growth factor (EGF) signaling by mutant huntingtin (polyQ-htt) may contribute to the onset of behavioral deficits observed in Huntington's disease (HD) through a variety of mechanisms, including cerebrovascular dysfunction. Yet, whether EGF signaling modulates the development of HD pathology and the associated behavioral impairments remain unclear. To gain insight on this issue, we used the R6/2 mouse model of HD to assess the impact of chronic EGF treatment on behavior, and cerebrovascular and cortical neuronal functions. We found that bi-weekly treatment with a low dose of EGF (300 µg/kg, i.p.) for 6 weeks was sufficient to effectively improve motor behavior in R6/2 mice and diminish mortality, compared to vehicle-treated littermates. These beneficial effects of EGF treatment were dissociated from changes in cerebrovascular leakiness, a result that was surprising given that EGF ameliorates this deficit in other neurodegenerative diseases. Rather, the beneficial effect of EGF on R6/2 mice behavior was concomitant with a marked amelioration of cortical GABAergic function. As GABAergic transmission in cortical circuits is disrupted in HD, these novel data suggest a potential mechanistic link between deficits in EGF signaling and GABAergic dysfunction in the progression of HD.
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Affiliation(s)
- Felecia M Marottoli
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Mercedes Priego
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Eden Flores-Barrera
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Rohan Pisharody
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Steve Zaldua
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Kelly D Fan
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Giri K Ekkurthi
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Scott T Brady
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Gerardo A Morfini
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Kuei Y Tseng
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Leon M Tai
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois at Chicago, Chicago, IL, 60612, USA.
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17
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Burgold J, Schulz-Trieglaff EK, Voelkl K, Gutiérrez-Ángel S, Bader JM, Hosp F, Mann M, Arzberger T, Klein R, Liebscher S, Dudanova I. Cortical circuit alterations precede motor impairments in Huntington's disease mice. Sci Rep 2019; 9:6634. [PMID: 31036840 PMCID: PMC6488584 DOI: 10.1038/s41598-019-43024-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/12/2019] [Indexed: 12/15/2022] Open
Abstract
Huntington's disease (HD) is a devastating hereditary movement disorder, characterized by degeneration of neurons in the striatum and cortex. Studies in human patients and mouse HD models suggest that disturbances of neuronal function in the neocortex play an important role in disease onset and progression. However, the precise nature and time course of cortical alterations in HD have remained elusive. Here, we use chronic in vivo two-photon calcium imaging to longitudinally monitor the activity of identified single neurons in layer 2/3 of the primary motor cortex in awake, behaving R6/2 transgenic HD mice and wildtype littermates. R6/2 mice show age-dependent changes in cortical network function, with an increase in activity that affects a large fraction of cells and occurs rather abruptly within one week, preceeding the onset of motor defects. Furthermore, quantitative proteomics demonstrate a pronounced downregulation of synaptic proteins in the cortex, and histological analyses in R6/2 mice and human HD autopsy cases reveal a reduction in perisomatic inhibitory synaptic contacts on layer 2/3 pyramidal cells. Taken together, our study provides a time-resolved description of cortical network dysfunction in behaving HD mice and points to disturbed excitation/inhibition balance as an important pathomechanism in HD.
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Affiliation(s)
- Johanna Burgold
- Department of Molecules - Signaling - Development, Max Planck Institute of Neurobiology, 82152, Martinsried, Germany
| | | | - Kerstin Voelkl
- Department of Molecules - Signaling - Development, Max Planck Institute of Neurobiology, 82152, Martinsried, Germany
| | - Sara Gutiérrez-Ángel
- Department of Molecules - Signaling - Development, Max Planck Institute of Neurobiology, 82152, Martinsried, Germany
| | - Jakob Maximilian Bader
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Fabian Hosp
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Thomas Arzberger
- German Center for Neurodegenerative Diseases (DZNE), 81377, Munich, Germany
- Center for Neuropathology and Prion Research, Ludwig-Maximilians University Munich, 81377, Munich, Germany
- Department of Psychiatry and Psychotherapy, Ludwig-Maximilians University Munich, 81377, Munich, Germany
| | - Rüdiger Klein
- Department of Molecules - Signaling - Development, Max Planck Institute of Neurobiology, 82152, Martinsried, Germany.
- Munich Cluster for Systems Neurology (SyNergy), 81377, Munich, Germany.
| | - Sabine Liebscher
- Munich Cluster for Systems Neurology (SyNergy), 81377, Munich, Germany.
- Institute of Clinical Neuroimmunology, Klinikum der Universität München, Ludwig-Maximilians University Munich, 82152, Martinsried, Germany.
- Biomedical Center, Medical Faculty, Ludwig-Maximilians University Munich, 82152, Martinsried, Germany.
| | - Irina Dudanova
- Department of Molecules - Signaling - Development, Max Planck Institute of Neurobiology, 82152, Martinsried, Germany.
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18
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Hsu YT, Chang YG, Chern Y. Insights into GABA Aergic system alteration in Huntington's disease. Open Biol 2018; 8:rsob.180165. [PMID: 30518638 PMCID: PMC6303784 DOI: 10.1098/rsob.180165] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 10/30/2018] [Indexed: 12/15/2022] Open
Abstract
Huntington's disease (HD) is an autosomal dominant progressive neurodegenerative disease that is characterized by a triad of motor, psychiatric and cognitive impairments. There is still no effective therapy to delay or halt the disease progress. The striatum and cortex are two particularly affected brain regions that exhibit dense reciprocal excitatory glutamate and inhibitory gamma-amino butyric acid (GABA) connections. Imbalance between excitatory and inhibitory signalling is known to greatly affect motor and cognitive processes. Emerging evidence supports the hypothesis that disrupted GABAergic circuits underlie HD pathogenesis. In the present review, we focused on the multiple defects recently found in the GABAergic inhibitory system, including altered GABA level and synthesis, abnormal subunit composition and distribution of GABAA receptors and aberrant GABAA receptor-mediated signalling. In particular, the important role of cation–chloride cotransporters (i.e. NKCC1 and KCC2) is discussed. Recent studies also suggest that neuroinflammation contributes significantly to the abnormal GABAergic inhibition in HD. Thus, GABAA receptors and cation–chloride cotransporters are potential therapeutic targets for HD. Given the limited availability of therapeutic treatments for HD, a better understanding of GABAergic dysfunction in HD could provide novel therapeutic opportunities.
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Affiliation(s)
- Yi-Ting Hsu
- PhD Program for Translational Medicine, China Medical University and Academia Sinica, Taiwan, Republic of China.,Department of Neurology, China Medical University Hospital, Taichung, Taiwan, Republic of China
| | - Ya-Gin Chang
- Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan, Republic of China.,Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Yang-Ming University and Academia Sinica, Taipei, Taiwan, Republic of China
| | - Yijuang Chern
- PhD Program for Translational Medicine, China Medical University and Academia Sinica, Taiwan, Republic of China .,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, Republic of China
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19
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Estrada-Sánchez AM, Castro D, Portillo-Ortiz K, Jang K, Nedjat-Haiem M, Levine MS, Cepeda C. Complete but not partial inhibition of glutamate transporters exacerbates cortical excitability in the R6/2 mouse model of Huntington's disease. CNS Neurosci Ther 2018; 25:509-518. [PMID: 30311425 DOI: 10.1111/cns.13070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/05/2018] [Accepted: 09/07/2018] [Indexed: 01/05/2023] Open
Abstract
AIM Deficient glutamate reuptake occurs in the cerebral cortex of Huntington's disease (HD) patients and murine models. Here, we examine the effects of partial or complete blockade of glutamate transporters on excitatory postsynaptic currents (EPSCs) of cortical pyramidal neurons (CPNs). METHODS Whole-cell patch clamp recordings of CPNs in slices from symptomatic R6/2 mice and wild-type (WT) littermates were used to examine the effects of selective or concurrent inhibition of glutamate reuptake transporters. RESULTS Selective inhibition of the glial glutamate transporter 1 (GLT-1) or the glutamate aspartate transporter (GLAST) produced slight decreases in decay time of evoked EPSCs in CPNs from WT and R6/2 mice with no significant differences between genotypes. In contrast, concurrent inhibition of both transporters with DL-TBOA induced a significant increase in area and decay time and this effect was significantly greater in R6/2 CPNs. Furthermore, full blockade also reduced spontaneous EPSC frequency and exacerbated epileptiform activity in CPNs from symptomatic R6/2 mice. CONCLUSIONS R6/2 CPNs are more sensitive to glutamate accumulation during full inhibition of both glutamate transporters, and these neurons have homeostatic mechanisms to cope with inhibition of GLT-1 or GLAST by a mechanism that involves upregulation of either transporter when the other is deficient.
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Affiliation(s)
- Ana María Estrada-Sánchez
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Daniel Castro
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Kenia Portillo-Ortiz
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Katrina Jang
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Michael Nedjat-Haiem
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Michael S Levine
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
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20
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Alpaugh M, Galleguillos D, Forero J, Morales LC, Lackey SW, Kar P, Di Pardo A, Holt A, Kerr BJ, Todd KG, Baker GB, Fouad K, Sipione S. Disease-modifying effects of ganglioside GM1 in Huntington's disease models. EMBO Mol Med 2018; 9:1537-1557. [PMID: 28993428 PMCID: PMC5666311 DOI: 10.15252/emmm.201707763] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Huntington's disease (HD) is a progressive neurodegenerative disorder characterized by motor, cognitive and psychiatric problems. Previous studies indicated that levels of brain gangliosides are lower than normal in HD models and that administration of exogenous ganglioside GM1 corrects motor dysfunction in the YAC128 mouse model of HD In this study, we provide evidence that intraventricular administration of GM1 has profound disease-modifying effects across HD mouse models with different genetic background. GM1 administration results in decreased levels of mutant huntingtin, the protein that causes HD, and in a wide array of beneficial effects that include changes in levels of DARPP32, ferritin, Iba1 and GFAP, modulation of dopamine and serotonin metabolism, and restoration of normal levels of glutamate, GABA, L-Ser and D-Ser. Treatment with GM1 slows down neurodegeneration, white matter atrophy and body weight loss in R6/2 mice. Motor functions are significantly improved in R6/2 mice and restored to normal in Q140 mice, including gait abnormalities that are often resistant to treatments. Psychiatric-like and cognitive dysfunctions are also ameliorated by GM1 administration in Q140 and YAC128 mice. The widespread benefits of GM1 administration, at molecular, cellular and behavioural levels, indicate that this ganglioside has strong therapeutic and disease-modifying potential in HD.
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Affiliation(s)
- Melanie Alpaugh
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Danny Galleguillos
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada.,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Juan Forero
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | | | | | - Preeti Kar
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Alba Di Pardo
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Andrew Holt
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Bradley J Kerr
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, AB, Canada
| | - Kathryn G Todd
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Glen B Baker
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Karim Fouad
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Simonetta Sipione
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada .,Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
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21
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Puigdellívol M, Saavedra A, Pérez-Navarro E. Cognitive dysfunction in Huntington's disease: mechanisms and therapeutic strategies beyond BDNF. Brain Pathol 2018; 26:752-771. [PMID: 27529673 DOI: 10.1111/bpa.12432] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 07/08/2016] [Indexed: 12/15/2022] Open
Abstract
One of the main focuses in Huntington's disease (HD) research, as well as in most neurodegenerative diseases, is the development of new therapeutic strategies, as currently there is no treatment to delay or prevent the progression of the disease. Neuronal dysfunction and neuronal death in HD are caused by a combination of interrelated pathogenic processes that lead to motor, cognitive and psychiatric symptoms. Understanding how mutant huntingtin impacts on a plethora of cellular functions could help to identify new molecular targets. Although HD has been classically classified as a neurodegenerative disease affecting voluntary movement, lately cognitive dysfunction is receiving increased attention as it is very invalidating for patients. Thus, an ambitious goal in HD research is to find altered molecular mechanisms that contribute to cognitive decline. In this review, we have focused on those findings related to corticostriatal and hippocampal cognitive dysfunction in HD, as well as on the underlying molecular mechanisms, which constitute potential therapeutic targets. These include alterations in synaptic plasticity, transcriptional machinery and neurotrophic and neurotransmitter signaling.
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Affiliation(s)
- Mar Puigdellívol
- Departament de Biomedicina, Facultat de Medicina, Universitat de Barcelona, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED), Spain
| | - Ana Saavedra
- Departament de Biomedicina, Facultat de Medicina, Universitat de Barcelona, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED), Spain.,Institut de Neurociències, Universitat de Barcelona, Catalonia, Spain
| | - Esther Pérez-Navarro
- Departament de Biomedicina, Facultat de Medicina, Universitat de Barcelona, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED), Spain.,Institut de Neurociències, Universitat de Barcelona, Catalonia, Spain
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22
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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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23
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Rangel-Barajas C, Rebec GV. Dysregulation of Corticostriatal Connectivity in Huntington's Disease: A Role for Dopamine Modulation. J Huntingtons Dis 2017; 5:303-331. [PMID: 27983564 PMCID: PMC5181679 DOI: 10.3233/jhd-160221] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Aberrant communication between striatum, the main information processing unit of the basal ganglia, and cerebral cortex plays a critical role in the emergence of Huntington’s disease (HD), a fatal monogenetic condition that typically strikes in the prime of life. Although both striatum and cortex undergo substantial cell loss over the course of HD, corticostriatal circuits become dysfunctional long before neurons die. Understanding the dysfunction is key to developing effective strategies for treating a progressively worsening triad of motor, cognitive, and psychiatric symptoms. Cortical output neurons drive striatal activity through the release of glutamate, an excitatory amino acid. Striatal outputs, in turn, release γ-amino butyric acid (GABA) and exert inhibitory control over downstream basal ganglia targets. Ample evidence from transgenic rodent models points to dysregulation of corticostriatal glutamate transmission along with corresponding changes in striatal GABA release as underlying factors in the HD behavioral phenotype. Another contributor is dysregulation of dopamine (DA), a modulator of both glutamate and GABA transmission. In fact, pharmacological manipulation of DA is the only currently available treatment for HD symptoms. Here, we review data from animal models and human patients to evaluate the role of DA in HD, including DA interactions with glutamate and GABA within the context of dysfunctional corticostriatal circuitry.
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Affiliation(s)
| | - George V. Rebec
- Correspondence to: George V. Rebec, PhD, Department of Psychological and Brain Sciences, Program in
Neuroscience, Indiana University, 1101 E. 10th Street, Bloomington, IN 47405-7007, USA. Tel.: +1 812 855 4832;
Fax: +1 812 855 4520; E-mail:
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24
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Tyebji S, Hannan AJ. Synaptopathic mechanisms of neurodegeneration and dementia: Insights from Huntington's disease. Prog Neurobiol 2017; 153:18-45. [PMID: 28377290 DOI: 10.1016/j.pneurobio.2017.03.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 03/19/2017] [Accepted: 03/30/2017] [Indexed: 12/20/2022]
Abstract
Dementia encapsulates a set of symptoms that include loss of mental abilities such as memory, problem solving or language, and reduces a person's ability to perform daily activities. Alzheimer's disease is the most common form of dementia, however dementia can also occur in other neurological disorders such as Huntington's disease (HD). Many studies have demonstrated that loss of neuronal cell function manifests pre-symptomatically and thus is a relevant therapeutic target to alleviate symptoms. Synaptopathy, the physiological dysfunction of synapses, is now being approached as the target for many neurological and psychiatric disorders, including HD. HD is an autosomal dominant and progressive degenerative disorder, with clinical manifestations that encompass movement, cognition, mood and behaviour. HD is one of the most common tandem repeat disorders and is caused by a trinucleotide (CAG) repeat expansion, encoding an extended polyglutamine tract in the huntingtin protein. Animal models as well as human studies have provided detailed, although not exhaustive, evidence of synaptic dysfunction in HD. In this review, we discuss the neuropathology of HD and how the changes in synaptic signalling in the diseased brain lead to its symptoms, which include dementia. Here, we review and discuss the mechanisms by which the 'molecular orchestras' and their 'synaptic symphonies' are disrupted in neurodegeneration and dementia, focusing on HD as a model disease. We also explore the therapeutic strategies currently in pre-clinical and clinical testing that are targeted towards improving synaptic function in HD.
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Affiliation(s)
- Shiraz Tyebji
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Anthony J Hannan
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia; Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia.
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Mehrabi NF, Waldvogel HJ, Tippett LJ, Hogg VM, Synek BJ, Faull RLM. Symptom heterogeneity in Huntington's disease correlates with neuronal degeneration in the cerebral cortex. Neurobiol Dis 2016; 96:67-74. [PMID: 27569581 DOI: 10.1016/j.nbd.2016.08.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 08/19/2016] [Accepted: 08/24/2016] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Huntington's disease (HD) is characterised by variable symptoms and neuropathology of the basal ganglia and cortex. Previously, we have shown that the pattern of pyramidal cell loss in 8 different cortical regions correlates with the phenotypic variability in HD. In the primary motor and anterior cingulate cortices, the pattern of interneuron degeneration correlates with pyramidal cell death and variable HD symptom profiles. OBJECTIVES This study aimed to examine the pattern of interneuron degeneration in 3 further regions of the HD cortex (primary sensory, superior frontal, superior parietal cortices) to determine whether HD neuropathogenesis was characterised by a general fundamental pattern of cortical interneuron loss, and explore the relationship between cortical interneuron loss with previously determined pyramidal cell loss and clinical heterogeneity. METHODS Stereological counting was used to quantify 3 sub-populations of calcium-binding protein containing interneurons in 3 cortical human brain regions of 14 HD and 13 control cases as used in our previous studies (Nana et al., 2014; Kim et al., 2014). The HD cases were grouped according to their predominant symptom profile ("motor", "mood", "mixed"). RESULTS The present results demonstrated a heterogeneous loss of interneurons across the 3 cortical regions which, when compared with our previous studies, mirrored the pattern of pyramidal cell loss in the same cortical areas. Most interestingly, the pattern of neuronal loss in these regions correlated with the variable HD symptom profiles. CONCLUSION The overall findings in our present and previous cortical studies establish a clear correlative pattern of variable cortical neuronal degeneration in HD pathogenesis, which mirrors the heterogeneity of HD symptom phenotypes.
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Affiliation(s)
- Nasim F Mehrabi
- Centre for Brain Research, University of Auckland, Auckland, New Zealand; Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
| | - Henry J Waldvogel
- Centre for Brain Research, University of Auckland, Auckland, New Zealand; Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
| | - Lynette J Tippett
- Centre for Brain Research, University of Auckland, Auckland, New Zealand; Department of Psychology, University of Auckland, Auckland, New Zealand
| | - Virginia M Hogg
- Centre for Brain Research, University of Auckland, Auckland, New Zealand; Department of Psychology, University of Auckland, Auckland, New Zealand
| | - Beth J Synek
- Centre for Brain Research, University of Auckland, Auckland, New Zealand; Forensic Pathology, Auckland City Hospital, Auckland, New Zealand
| | - Richard L M Faull
- Centre for Brain Research, University of Auckland, Auckland, New Zealand; Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand.
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Mantovani S, Gordon R, Li R, Christie DC, Kumar V, Woodruff TM. Motor deficits associated with Huntington's disease occur in the absence of striatal degeneration in BACHD transgenic mice. Hum Mol Genet 2016; 25:1780-91. [PMID: 26908618 DOI: 10.1093/hmg/ddw050] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 02/15/2016] [Indexed: 11/12/2022] Open
Abstract
Huntington's disease (HD) is an incurable neurodegenerative condition characterized by progressive motor and cognitive dysfunction, and depletion of neurons in the striatum. Recently, BACHD transgenic mice expressing the full-length human huntingtin gene have been generated, which recapitulate some of the motor and cognitive deficits seen in HD. In this study, we carried out a series of extensive behavioural and neuropathological tests on BACHD mice, to validate this mouse for preclinical research. Transgenic C57BL/6J BACHD and litter-matched wild-type mice were examined in a battery of motor and cognitive function tests at regular intervals up to 12 months of age. Brains from these mice were also analysed for signs of neurodegeneration and striatal and cortical volume sizes compared using anatomic 16.4T magnetic resonance imaging (MRI) brain scans. BACHD mice showed progressive motor impairments on rotarod and balance beam tests starting from 3 months of age, were hypoactive in the open field tests starting from 6 months of age, however, showed no alterations in gait and grip strength at any age. Surprisingly, despite these distinct motor deficits, no signs of neuronal loss, gliosis or blood-brain barrier degeneration were observed in the striatum of 12-month-old mice. MRI brain scans confirmed no reduction in striatal or cortical volumes at 12 months of age, and BACHD mice had a normal lifespan. These results demonstrate that classical Huntington's-like motor impairments seen in this transgenic model, do not occur due to degeneration of the striatum, and thus caution against the use of this model for preclinical studies into HD.
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Affiliation(s)
- Susanna Mantovani
- School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD, Australia and Wesley Medical Research, Auchenflower, Brisbane, QLD, Australia
| | - Richard Gordon
- School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD, Australia and
| | - Rui Li
- School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD, Australia and
| | - Daniel C Christie
- School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD, Australia and
| | - Vinod Kumar
- School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD, Australia and
| | - Trent M Woodruff
- School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD, Australia and
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Cortical efferents lacking mutant huntingtin improve striatal neuronal activity and behavior in a conditional mouse model of Huntington's disease. J Neurosci 2015; 35:4440-51. [PMID: 25762686 DOI: 10.1523/jneurosci.2812-14.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Abnormal electrophysiological activity in the striatum, which receives dense innervation from the cerebral cortex, is believed to set the stage for the behavioral phenotype observed in Huntington's disease (HD), a neurodegenerative condition caused by mutation of the huntingtin (mhtt) protein. However, cortical involvement is far from clear. To determine whether abnormal striatal processing can be explained by mhtt alone (cell-autonomous model) or by mhtt in the corticostriatal projection cell-cell interaction model, we used BACHD/Emx1-Cre (BE) mice, a conditional HD model in which full-length mhtt is genetically reduced in cortical output neurons, including those that project to the striatum. Animals were assessed beginning at 20 weeks of age for at least the next 40 weeks, a range over which presymptomatic BACHD mice become symptomatic. Both open-field and nest-building behavior deteriorated progressively in BACHD mice relative to both BE and wild-type (WT) mice. Neuronal activity patterns in the dorsal striatum, which receives input from the primary motor cortex (M1), followed a similar age progression because BACHD activity changed more rapidly than either BE or WT mice. However, in the M1, BE neuronal activity differed significantly from both WT and BACHD. Although abnormal cortical activity in BE mice likely reflects input from mhtt-expressing afferents, including cortical interneurons, improvements in BE striatal activity and behavior suggest a critical role for mhtt in cortical output neurons in shaping the onset and progression of striatal dysfunction.
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Roselli F, Caroni P. From Intrinsic Firing Properties to Selective Neuronal Vulnerability in Neurodegenerative Diseases. Neuron 2015; 85:901-10. [DOI: 10.1016/j.neuron.2014.12.063] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Indersmitten T, Tran CH, Cepeda C, Levine MS. Altered excitatory and inhibitory inputs to striatal medium-sized spiny neurons and cortical pyramidal neurons in the Q175 mouse model of Huntington's disease. J Neurophysiol 2015; 113:2953-66. [PMID: 25673747 DOI: 10.1152/jn.01056.2014] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 02/10/2015] [Indexed: 11/22/2022] Open
Abstract
The Q175 knockin mouse model of Huntington's disease (HD) carries a CAG trinucleotide expansion of the human mutant huntingtin allele in its native mouse genomic context and recapitulates the genotype more closely than transgenic models. In this study we examined the progression of changes in intrinsic membrane properties and excitatory and inhibitory synaptic transmission, using whole cell patch-clamp recordings of medium-sized spiny neurons (MSNs) in the dorsolateral striatum and cortical pyramidal neurons (CPNs) in layers 2/3 of the primary motor cortex in brain slices from heterozygous (Q175(+/-)) and homozygous (Q175(+/+)) mice. Input resistance in MSNs from Q175(+/+) and Q175(+/-) mice was significantly increased compared with wild-type (WT) littermates beginning at 2 mo. Furthermore, the frequency of spontaneous and miniature excitatory postsynaptic currents (EPSCs) was significantly reduced in MSNs from Q175(+/+) and Q175(+/-) mice compared with WTs beginning at 7 mo. In contrast, the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) and IPSC-to-EPSC ratios were increased in MSNs from Q175(+/+) mice beginning at 2 mo. Morphologically, significant decreases in spine density of MSNs from Q175(+/-) and Q175(+/+) mice occurred at 7 and 12 mo. In CPNs, sIPSC frequencies and IPSC-to-EPSC ratios were significantly increased in Q175(+/-) mice compared with WTs at 12 mo. There were no changes in intrinsic membrane properties or morphology. In summary, we show a number of alterations in electrophysiological and morphological properties of MSNs in Q175 mice that are similar to other HD mouse models. However, unlike other models, CPN inhibitory activity is increased in Q175(+/-) mice, indicating reduced cortical excitability.
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Affiliation(s)
- Tim Indersmitten
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, California
| | - Conny H Tran
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, California
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, California
| | - Michael S Levine
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, California
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30
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Abstract
In this review, we explore the similarities and differences in the behavioural neurobiology found in the mouse models of Huntington's disease (HD) and the human disease state. The review is organised with a comparative focus on the functional domains of motor control, cognition and behavioural disturbance (akin to psychiatric disturbance in people) and how our knowledge of the underlying physiological changes that are manifest in the HD mouse lines correspond to those seen in the HD clinical population. The review is framed in terms of functional circuitry and neurotransmitter systems and how abnormalities in these systems impact on the behavioural readouts across the mouse lines and how these may correspond to the deficits observed in people. In addition, interpretational issues associated with the data from animal studies are discussed.
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Affiliation(s)
- Simon P Brooks
- Brain Repair Group, Division of Neuroscience, Cardiff University School of Bioscience, Museum Avenue, Cardiff, Wales, UK,
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Waldvogel HJ, Kim EH, Tippett LJ, Vonsattel JPG, Faull RLM. The Neuropathology of Huntington's Disease. Curr Top Behav Neurosci 2015; 22:33-80. [PMID: 25300927 DOI: 10.1007/7854_2014_354] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The basal ganglia are a highly interconnected set of subcortical nuclei and major atrophy in one or more regions may have major effects on other regions of the brain. Therefore, the striatum which is preferentially degenerated and receives projections from the entire cortex also affects the regions to which it targets, especially the globus pallidus and substantia nigra pars reticulata. Additionally, the cerebral cortex is itself severely affected as are many other regions of the brain, especially in more advanced cases. The cell loss in the basal ganglia and the cerebral cortex is extensive. The most important new findings in Huntington's disease pathology is the highly variable nature of the degeneration in the brain. Most interestingly, this variable pattern of pathology appears to reflect the highly variable symptomatology of cases with Huntington's disease even among cases possessing the same number of CAG repeats.
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Affiliation(s)
- Henry J Waldvogel
- Centre for Brain Research, Department of Anatomy with Radiology, University of Auckland, Auckland, New Zealand,
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Waldvogel H, Faull R. The Diversity of GABAA Receptor Subunit Distribution in the Normal and Huntington's Disease Human Brain1. DIVERSITY AND FUNCTIONS OF GABA RECEPTORS: A TRIBUTE TO HANNS MÖHLER, PART B 2015; 73:223-64. [DOI: 10.1016/bs.apha.2014.11.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Ponomareva N, Klyushnikov S, Abramycheva N, Malina D, Scheglova N, Fokin V, Ivanova-Smolenskaia I, Illarioshkin S. Alpha-theta border EEG abnormalities in preclinical Huntington's disease. J Neurol Sci 2014; 344:114-20. [PMID: 25015843 DOI: 10.1016/j.jns.2014.06.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Revised: 05/23/2014] [Accepted: 06/17/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Brain dysfunction precedes clinical manifestation of Huntington's disease (HD) by decades. This study was aimed to determine whether resting EEG is altered in preclinical HD mutations carriers (pre-HD). METHODS We examined relative power of broad traditional EEG bands as well as 1-Hz sub-bands of theta and alpha from the resting-state EEG of 29 pre-HD individuals and of 29 age-matched normal controls. RESULTS The relative power of the narrow sub-band in the border of theta-alpha (7-8 Hz) was significantly reduced in pre-HD subjects as compared to normal controls, while the alterations in relative power of the broad frequency bands were not significant. In pre-HD subjects, the number of CAG repeats in the huntingtin (HTT) gene as well as the disease burden score (DBS) showed a positive correlation with relative power of the delta and theta frequency bands and their sub-bands and a negative correlation with alpha band relative power and the differences of relative power of the 7-8 Hz and 4-5 Hz frequency sub-bands. CONCLUSION The obtained results suggest that EEG alterations in pre-HD individuals may be related to the course of the pathological process and to HD endophenotype. Analysis of the narrow EEG bands was found to be more useful for assessing EEG alterations in pre-HD individuals than a more traditional approach using broad bandwidths.
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Affiliation(s)
- Natalya Ponomareva
- Department for Brain Research, Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia.
| | - Sergey Klyushnikov
- Department of Neurogenetics, Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Natalya Abramycheva
- Department of Neurogenetics, Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Daria Malina
- Department for Brain Research, Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Nadejda Scheglova
- Department for Brain Research, Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Vitaly Fokin
- Department for Brain Research, Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Irina Ivanova-Smolenskaia
- Department of Neurogenetics, Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Sergey Illarioshkin
- Department for Brain Research, Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia; Department of Neurogenetics, Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
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Kim EH, Thu DCV, Tippett LJ, Oorschot DE, Hogg VM, Roxburgh R, Synek BJ, Waldvogel HJ, Faull RLM. Cortical interneuron loss and symptom heterogeneity in Huntington disease. Ann Neurol 2014; 75:717-27. [DOI: 10.1002/ana.24162] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 04/22/2014] [Accepted: 04/23/2014] [Indexed: 12/21/2022]
Affiliation(s)
- Eric H. Kim
- Department of Anatomy with Radiology; University of Auckland; Auckland New Zealand
- Centre for Brain Research; University of Auckland; Auckland New Zealand
| | - Doris C. V. Thu
- Centre for Brain Research; University of Auckland; Auckland New Zealand
- Brain Mind Institute, Lausanne Federal Polytechnic School; Lausanne Switzerland
| | - Lynette J. Tippett
- Centre for Brain Research; University of Auckland; Auckland New Zealand
- Department of Psychology; University of Auckland; Auckland New Zealand
| | - Dorothy E. Oorschot
- Department of Anatomy; University of Otago; Dunedin New Zealand
- Brain Health Research Centre; University of Otago; Dunedin New Zealand
| | - Virginia M. Hogg
- Centre for Brain Research; University of Auckland; Auckland New Zealand
- Department of Psychology; University of Auckland; Auckland New Zealand
| | - Richard Roxburgh
- Centre for Brain Research; University of Auckland; Auckland New Zealand
- Neurology; Auckland City Hospital; Auckland New Zealand
| | - Beth J. Synek
- Centre for Brain Research; University of Auckland; Auckland New Zealand
- Forensic Pathology; Auckland City Hospital; Auckland New Zealand
| | - Henry J. Waldvogel
- Department of Anatomy with Radiology; University of Auckland; Auckland New Zealand
- Centre for Brain Research; University of Auckland; Auckland New Zealand
| | - Richard L. M. Faull
- Department of Anatomy with Radiology; University of Auckland; Auckland New Zealand
- Centre for Brain Research; University of Auckland; Auckland New Zealand
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Scheff SW, Neltner JH, Nelson PT. Is synaptic loss a unique hallmark of Alzheimer's disease? Biochem Pharmacol 2014; 88:517-28. [PMID: 24412275 DOI: 10.1016/j.bcp.2013.12.028] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 12/29/2013] [Accepted: 12/30/2013] [Indexed: 12/13/2022]
Abstract
Synapses may represent a key nidus for dementia including Alzheimer's disease (AD) pathogenesis. Here we review published studies and present new ideas related to the question of the specificity of synapse loss in AD. Currently, AD is defined by the regional presence of neuritic plaques and neurofibrillary tangles in the brain. The severity of involvement by those pathological hallmarks tends to correlate both with antemortem cognitive status, and also with synapse loss in multiple brain areas. Recent studies from large autopsy series have led to a new standard of excellence with regard to clinical-pathological correlation and to improved comprehension of the numerous brain diseases of the elderly. These studies have provided evidence that it is the rule rather than the exception for brains of aged individuals to demonstrate pathologies (often multiple) other than AD plaques and tangles. For many of these comorbid pathologies, the extent of synapse loss is imperfectly understood but could be substantial. These findings indicate that synapse loss is probably not a hallmark specific to AD but rather a change common to many diseases associated with dementia.
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Affiliation(s)
- Stephen W Scheff
- Department of Anatomy and Neurobiology, University of Kentucky Medical Center, University of Kentucky, Lexington, KY 40536, United States; Sanders-Brown Center on Aging and Alzheimer's Disease Center, University of Kentucky Medical Center, University of Kentucky, Lexington, KY 40536, United States.
| | - Janna H Neltner
- Department of Pathology and Division of Neuropathology, University of Kentucky Medical Center, University of Kentucky, Lexington, KY 40536, United States
| | - Peter T Nelson
- Sanders-Brown Center on Aging and Alzheimer's Disease Center, University of Kentucky Medical Center, University of Kentucky, Lexington, KY 40536, United States; Department of Pathology and Division of Neuropathology, University of Kentucky Medical Center, University of Kentucky, Lexington, KY 40536, United States.
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Rebec GV. Dysregulation of corticostriatal ascorbate release and glutamate uptake in transgenic models of Huntington's disease. Antioxid Redox Signal 2013; 19:2115-28. [PMID: 23642110 PMCID: PMC3869431 DOI: 10.1089/ars.2013.5387] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 05/05/2013] [Indexed: 11/13/2022]
Abstract
SIGNIFICANCE Dysregulation of cortical and striatal neuronal processing plays a critical role in Huntington's disease (HD), a dominantly inherited condition that includes a progressive deterioration of cognitive and motor control. Growing evidence indicates that ascorbate (AA), an antioxidant vitamin, is released into striatal extracellular fluid when glutamate is cleared after its release from cortical afferents. Both AA release and glutamate uptake are impaired in the striatum of transgenic mouse models of HD owing to a downregulation of glutamate transporter 1 (GLT1), the protein primarily found on astrocytes and responsible for removing most extracellular glutamate. Improved understanding of an AA-glutamate interaction could lead to new therapeutic strategies for HD. RECENT ADVANCES Increased expression of GLT1 following treatment with ceftriaxone, a beta-lactam antibiotic, increases striatal glutamate uptake and AA release and also improves the HD behavioral phenotype. In fact, treatment with AA alone restores striatal extracellular AA to wild-type levels in HD mice and not only improves behavior but also improves the firing pattern of neurons in HD striatum. CRITICAL ISSUES Although evidence is growing for an AA-glutamate interaction, several key issues require clarification: the site of action of AA on striatal neurons; the precise role of GLT1 in striatal AA release; and the mechanism by which HD interferes with this role. FUTURE DIRECTIONS Further assessment of how the HD mutation alters corticostriatal signaling is an important next step. A critical focus is the role of astrocytes, which express GLT1 and may be the primary source of extracellular AA.
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Affiliation(s)
- George V Rebec
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University , Bloomington, Indiana
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Simmons DA, Belichenko NP, Yang T, Condon C, Monbureau M, Shamloo M, Jing D, Massa SM, Longo FM. A small molecule TrkB ligand reduces motor impairment and neuropathology in R6/2 and BACHD mouse models of Huntington's disease. J Neurosci 2013; 33:18712-27. [PMID: 24285878 PMCID: PMC3841443 DOI: 10.1523/jneurosci.1310-13.2013] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 09/09/2013] [Accepted: 10/12/2013] [Indexed: 02/08/2023] Open
Abstract
Loss of neurotrophic support in the striatum caused by reduced brain-derived neurotrophic factor (BDNF) levels plays a critical role in Huntington's disease (HD) pathogenesis. BDNF acts via TrkB and p75 neurotrophin receptors (NTR), and restoring its signaling is a prime target for HD therapeutics. Here we sought to determine whether a small molecule ligand, LM22A-4, specific for TrkB and without effects on p75(NTR), could alleviate HD-related pathology in R6/2 and BACHD mouse models of HD. LM22A-4 was administered to R6/2 mice once daily (5-6 d/week) from 4 to 11 weeks of age via intraperitoneal and intranasal routes simultaneously to maximize brain levels. The ligand reached levels in the R6/2 forebrain greater than the maximal neuroprotective dose in vitro and corrected deficits in activation of striatal TrkB and its key signaling intermediates AKT, PLCγ, and CREB. Ligand-induced TrkB activation was associated with a reduction in HD pathologies in the striatum including decreased DARPP-32 levels, neurite degeneration of parvalbumin-containing interneurons, inflammation, and intranuclear huntingtin aggregates. Aggregates were also reduced in the cortex. Notably, LM22A-4 prevented deficits in dendritic spine density of medium spiny neurons. Moreover, R6/2 mice given LM22A-4 demonstrated improved downward climbing and grip strength compared with those given vehicle, though these groups had comparable rotarod performances and survival times. In BACHD mice, long-term LM22A-4 treatment (6 months) produced similar ameliorative effects. These results support the hypothesis that targeted activation of TrkB inhibits HD-related degenerative mechanisms, including spine loss, and may provide a disease mechanism-directed therapy for HD and other neurodegenerative conditions.
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Affiliation(s)
| | | | - Tao Yang
- Department of Neurology and Neurological Sciences and
| | | | - Marie Monbureau
- Behavioral and Functional Neuroscience Laboratory, Institute for Neuro-Innovation and Translational Neurosciences, Stanford University School of Medicine, Stanford, California 94305
| | - Mehrdad Shamloo
- Behavioral and Functional Neuroscience Laboratory, Institute for Neuro-Innovation and Translational Neurosciences, Stanford University School of Medicine, Stanford, California 94305
| | - Deqiang Jing
- Department of Psychiatry, Weill Cornell Medical College, New York, New York 10021, and
| | - Stephen M. Massa
- Department of Neurology and Laboratory for Computational Neurochemistry and Drug Discovery, Department of Veterans Affairs Medical Center and Department of Neurology, University of California, San Francisco, San Francisco, California 94121
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Dougherty SE, Hollimon JJ, McMeekin LJ, Bohannon AS, West AB, Lesort M, Hablitz JJ, Cowell RM. Hyperactivity and cortical disinhibition in mice with restricted expression of mutant huntingtin to parvalbumin-positive cells. Neurobiol Dis 2013; 62:160-71. [PMID: 24121117 DOI: 10.1016/j.nbd.2013.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 09/20/2013] [Accepted: 10/02/2013] [Indexed: 11/18/2022] Open
Abstract
Recent evidence suggests that interneurons are involved in the pathophysiology of Huntington Disease (HD). Abnormalities in the function of interneurons expressing the calcium buffer parvalbumin (PV) have been observed in multiple mouse models of HD, although it is not clear how PV-positive interneuron dysfunction contributes to behavioral and synaptic deficits. Here, we use the cre-lox system to drive expression of mutant huntingtin (mthtt) in parvalbumin (PV)-positive neurons and find that mutant mice exhibit diffuse mthtt immunoreactivity in PV-rich areas at 10months of age and mthtt aggregates in PV-positive processes at 24months of age. At midlife, mutant mice are hyperactive and display impaired GABA release in the motor cortex, characterized by reduced miniature inhibitory events and severely blunted responses to gamma frequency stimulation, without a loss of PV-positive interneurons. In contrast, 24month-old mutant mice show normalized behavior and responses to gamma frequency stimulation, possibly due to compensatory changes in pyramidal neurons or the formation of inclusions with age. These data indicate that mthtt expression in PV-positive neurons is sufficient to drive a hyperactive phenotype and suggest that mthtt-mediated dysfunction in PV-positive neuronal populations could be a key factor in the hyperkinetic behavior observed in HD. Further clarification of the roles for specific PV-positive populations in this phenotype is warranted to definitively identify cellular targets for intervention.
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Affiliation(s)
- S E Dougherty
- Neuroscience Graduate Program, University of Alabama at Birmingham, 35294, USA; Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA
| | - J J Hollimon
- Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA
| | - L J McMeekin
- Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA
| | - A S Bohannon
- Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA
| | - A B West
- Department of Neurology, University of Alabama at Birmingham, 35294, USA
| | - M Lesort
- Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA
| | - J J Hablitz
- Department of Neurobiology, University of Alabama at Birmingham, 35294, USA
| | - R M Cowell
- Department of Psychiatry & Behavioral Neurobiology, University of Alabama at Birmingham, 35294, USA.
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Chen JY, Wang EA, Cepeda C, Levine MS. Dopamine imbalance in Huntington's disease: a mechanism for the lack of behavioral flexibility. Front Neurosci 2013; 7:114. [PMID: 23847463 PMCID: PMC3701870 DOI: 10.3389/fnins.2013.00114] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/13/2013] [Indexed: 01/10/2023] Open
Abstract
Dopamine (DA) plays an essential role in the control of coordinated movements. Alterations in DA balance in the striatum lead to pathological conditions such as Parkinson's and Huntington's diseases (HD). HD is a progressive, invariably fatal neurodegenerative disease caused by a genetic mutation producing an expansion of glutamine repeats and is characterized by abnormal dance-like movements (chorea). The principal pathology is the loss of striatal and cortical projection neurons. Changes in brain DA content and receptor number contribute to abnormal movements and cognitive deficits in HD. In particular, during the early hyperkinetic stage of HD, DA levels are increased whereas expression of DA receptors is reduced. In contrast, in the late akinetic stage, DA levels are significantly decreased and resemble those of a Parkinsonian state. Time-dependent changes in DA transmission parallel biphasic changes in glutamate synaptic transmission and may enhance alterations in glutamate receptor-mediated synaptic activity. In this review, we focus on neuronal electrophysiological mechanisms that may lead to some of the motor and cognitive symptoms of HD and how they relate to dysfunction in DA neurotransmission. Based on clinical and experimental findings, we propose that some of the behavioral alterations in HD, including reduced behavioral flexibility, may be caused by altered DA modulatory function. Thus, restoring DA balance alone or in conjunction with glutamate receptor antagonists could be a viable therapeutic approach.
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Affiliation(s)
- Jane Y Chen
- 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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Wootz H, Fitzsimons-Kantamneni E, Larhammar M, Rotterman TM, Enjin A, Patra K, André E, Van Zundert B, Kullander K, Alvarez FJ. Alterations in the motor neuron-renshaw cell circuit in the Sod1(G93A) mouse model. J Comp Neurol 2013; 521:1449-69. [PMID: 23172249 DOI: 10.1002/cne.23266] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 09/14/2012] [Accepted: 11/06/2012] [Indexed: 12/12/2022]
Abstract
Motor neurons become hyperexcitable during progression of amyotrophic lateral sclerosis (ALS). This abnormal firing behavior has been explained by changes in their membrane properties, but more recently it has been suggested that changes in premotor circuits may also contribute to this abnormal activity. The specific circuits that may be altered during development of ALS have not been investigated. Here we examined the Renshaw cell recurrent circuit that exerts inhibitory feedback control on motor neuron firing. Using two markers for Renshaw cells (calbindin and cholinergic nicotinic receptor subunit alpha2 [Chrna2]), two general markers for motor neurons (NeuN and vesicular acethylcholine transporter [VAChT]), and two markers for fast motor neurons (Chondrolectin and calcitonin-related polypeptide alpha [Calca]), we analyzed the survival and connectivity of these cells during disease progression in the Sod1(G93A) mouse model. Most calbindin-immunoreactive (IR) Renshaw cells survive to end stage but downregulate postsynaptic Chrna2 in presymptomatic animals. In motor neurons, some markers are downregulated early (NeuN, VAChT, Chondrolectin) and others at end stage (Calca). Early downregulation of presynaptic VAChT and Chrna2 was correlated with disconnection from Renshaw cells as well as major structural abnormalities of motor axon synapses inside the spinal cord. Renshaw cell synapses on motor neurons underwent more complex changes, including transitional sprouting preferentially over remaining NeuN-IR motor neurons. We conclude that the loss of presynaptic motor axon input on Renshaw cells occurs at early stages of ALS and disconnects the recurrent inhibitory circuit, presumably resulting in diminished control of motor neuron firing. J. Comp. Neurol. 521:1449-1469, 2013. © 2012 Wiley Periodicals, Inc.
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Affiliation(s)
- Hanna Wootz
- Department of Neuroscience, Uppsala University, 75124 Uppsala, Sweden
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Estrada-Sánchez AM, Rebec GV. Role of cerebral cortex in the neuropathology of Huntington's disease. Front Neural Circuits 2013; 7:19. [PMID: 23423362 PMCID: PMC3575072 DOI: 10.3389/fncir.2013.00019] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 01/28/2013] [Indexed: 11/13/2022] Open
Abstract
An expansion of glutamine repeats in the N-terminal domain of the huntingtin protein leads to Huntington's disease (HD), a neurodegenerative condition characterized by the presence of involuntary movements, dementia, and psychiatric disturbances. Evaluation of postmortem HD tissue indicates that the most prominent cell loss occurs in cerebral cortex and striatum, forebrain regions in which cortical pyramidal neurons (CPNs) and striatal medium spiny neurons (MSNs) are the most affected. Subsequent evidence obtained from HD patients and especially from transgenic mouse models of HD indicates that long before neuronal death, patterns of communication between CPNs and MSNs become dysfunctional. In fact, electrophysiological signaling in transgenic HD mice is altered even before the appearance of the HD behavioral phenotype, suggesting that dysfunctional cortical input to the striatum sets the stage for the emergence of HD neurological signs. Striatal MSNs, moreover, project back to cortex via multi-synaptic connections, allowing for even further disruptions in cortical processing. An effective therapeutic strategy for HD, therefore, may lie in understanding the synaptic mechanisms by which it dysregulates the corticostriatal system. Here, we review literature evaluating the molecular, morphological, and physiological alterations in the cerebral cortex, a key component of brain circuitry controlling motor behavior, as they occur in both patients and transgenic HD models.
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Affiliation(s)
- Ana M Estrada-Sánchez
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University Bloomington, IN, USA
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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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Corticostriatal dysfunction and glutamate transporter 1 (GLT1) in Huntington's disease: interactions between neurons and astrocytes. ACTA ACUST UNITED AC 2012; 2:57-66. [PMID: 22905336 DOI: 10.1016/j.baga.2012.04.029] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Huntington's Disease (HD) is a fatally inherited neurodegenerative disorder caused by an expanded glutamine repeat in the N-terminal region of the huntingtin (HTT) protein. The result is a progressively worsening triad of cognitive, emotional, and motor alterations that typically begin in adulthood and end in death 10-20 years later. Autopsy of HD patients indicates massive cell loss in the striatum and its main source of input, the cerebral cortex. Further studies of HD patients and transgenic animal models of HD indicate that corticostriatal neuronal processing is altered long before neuronal death takes place. In fact, altered neuronal function appears to be the primary driver of the HD behavioral phenotype, and dysregulation of glutamate, the excitatory amino acid released by corticostriatal afferents, is believed to play a critical role. Although mutant HTT interferes with the operation of multiple proteins related to glutamate transmission, consistent evidence links the expression of mutant HTT with reduced activity of glutamate transporter 1 (rodent GLT1 or human EAAT2), the astrocytic protein responsible for the bulk of glutamate uptake. Here, we review corticostriatal dysfunction in HD and focus on GLT1 and its expression in astrocytes as a possible therapeutic target.
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Ghiglieri V, Bagetta V, Calabresi P, Picconi B. Functional interactions within striatal microcircuit in animal models of Huntington's disease. Neuroscience 2012; 211:165-84. [DOI: 10.1016/j.neuroscience.2011.06.075] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 06/25/2011] [Accepted: 06/28/2011] [Indexed: 11/17/2022]
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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: 16] [Impact Index Per Article: 1.3] [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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Reduced activity of AMP-activated protein kinase protects against genetic models of motor neuron disease. J Neurosci 2012; 32:1123-41. [PMID: 22262909 DOI: 10.1523/jneurosci.6554-10.2012] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A growing body of research indicates that amyotrophic lateral sclerosis (ALS) patients and mouse models of ALS exhibit metabolic dysfunction. A subpopulation of ALS patients possesses higher levels of resting energy expenditure and lower fat-free mass compared to healthy controls. Similarly, two mutant copper zinc superoxide dismutase 1 (mSOD1) mouse models of familial ALS possess a hypermetabolic phenotype. The pathophysiological relevance of the bioenergetic defects observed in ALS remains largely elusive. AMP-activated protein kinase (AMPK) is a key sensor of cellular energy status and thus might be activated in various models of ALS. Here, we report that AMPK activity is increased in spinal cord cultures expressing mSOD1, as well as in spinal cord lysates from mSOD1 mice. Reducing AMPK activity either pharmacologically or genetically prevents mSOD1-induced motor neuron death in vitro. To investigate the role of AMPK in vivo, we used Caenorhabditis elegans models of motor neuron disease. C. elegans engineered to express human mSOD1 (G85R) in neurons develops locomotor dysfunction and severe fecundity defects when compared to transgenic worms expressing human wild-type SOD1. Genetic reduction of aak-2, the ortholog of the AMPK α2 catalytic subunit in nematodes, improved locomotor behavior and fecundity in G85R animals. Similar observations were made with nematodes engineered to express mutant tat-activating regulatory (TAR) DNA-binding protein of 43 kDa molecular weight. Altogether, these data suggest that bioenergetic abnormalities are likely to be pathophysiologically relevant to motor neuron disease.
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Yuen EY, Wei J, Zhong P, Yan Z. Disrupted GABAAR trafficking and synaptic inhibition in a mouse model of Huntington's disease. Neurobiol Dis 2012; 46:497-502. [PMID: 22402331 DOI: 10.1016/j.nbd.2012.02.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 01/24/2012] [Accepted: 02/20/2012] [Indexed: 01/20/2023] Open
Abstract
Growing evidence suggests that Huntington's disease (HD), a neurodegenerative movement disorder caused by the mutant huntingtin (htt) with an expanded polyglutamine (polyQ) repeat, is associated with the altered intracellular trafficking and synaptic function. GABA(A) receptors, the key determinant of the strength of synaptic inhibition, have been found to bind to the huntingtin associated protein 1 (HAP1). HAP1 serves as an adaptor linking GABA(A) receptors to the kinesin family motor protein 5 (KIF5), controlling the transport of GABA(A) receptors along microtubules in dendrites. In this study, we found that GABA(A)R-mediated synaptic transmission is significantly impaired in a transgenic mouse model of HD expressing polyQ-htt, which is accompanied by the diminished surface expression of GABA(A) receptors. Moreover, the GABA(A)R/HAP1/KIF5 complex is disrupted and dissociated from microtubules in the HD mouse model. These results suggest that GABA(A)R trafficking and function is impaired in HD, presumably due to the interference of KIF5-mediated microtubule-based transport of GABA(A) receptors. The diminished inhibitory synaptic efficacy could contribute to the loss of the excitatory/inhibitory balance, leading to increased neuronal excitotoxicity in HD.
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Affiliation(s)
- Eunice Y Yuen
- Department of Physiology and Biophysics, State University of New York at Buffalo, School of Medicine and Biomedical Sciences, Buffalo, NY 14214, USA
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Zhang Y, Friedlander RM. Using non-coding small RNAs to develop therapies for Huntington's disease. Gene Ther 2012; 18:1139-49. [PMID: 22158031 DOI: 10.1038/gt.2011.170] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Huntington's disease (HD) is caused by an expansion of CAG triplets at the 5' end of the HD gene, which encodes a pathologically elongated polyglutamine stretch near the N-terminus of huntingtin. HD is an incurable autosomal-dominant neurodegenerative disease characterized by movement disorder, as well as emotional distress and dementia. The newly discovered roles of the non-coding small RNAs in specific degradation or translational suppression of the targeted mRNAs suggest a potential therapeutic approach of post-transcriptional gene silencing that targets the underlying disease etiology rather than the downstream pathological consequences. From pre-clinical trials in different HD animal models to cells from HD patients, small RNA interference has been applied to 'allele-non-specifically or allele-specifically' silence the mutant HD transgene or endogenous mutant HD allele. Silencing the mutant HD transgene significantly inhibits neurodegeneration, improves motor control, and extends survival of HD mice. With future improvement of mutant allele selectivity (preserving the expression of the neuroprotective wild-type allele), target specificity, efficacy and safety, as well as optimization of delivery methods, small non-coding RNA-based therapeutic applications will be a promising approach to treat HD.
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Affiliation(s)
- Y Zhang
- Department of Neurological Surgery, UPMC Presbyterian Hospital, University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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Abstract
Background Wig-1 is a transcription factor regulated by p53 that can interact with hnRNP A2/B1, RNA Helicase A, and dsRNAs, which plays an important role in RNA and protein stabilization. in vitro studies have shown that wig-1 binds p53 mRNA and stabilizes it by protecting it from deadenylation. Furthermore, p53 has been implicated as a causal factor in neurodegenerative diseases based in part on its selective regulatory function on gene expression, including genes which, in turn, also possess regulatory functions on gene expression. In this study we focused on the wig-1 transcription factor as a downstream p53 regulated gene and characterized the effects of wig-1 down regulation on gene expression in mouse liver and brain. Methods and Results Antisense oligonucleotides (ASOs) were identified that specifically target mouse wig-1 mRNA and produce a dose-dependent reduction in wig-1 mRNA levels in cell culture. These wig-1 ASOs produced marked reductions in wig-1 levels in liver following intraperitoneal administration and in brain tissue following ASO administration through a single striatal bolus injection in FVB and BACHD mice. Wig-1 suppression was well tolerated and resulted in the reduction of mutant Htt protein levels in BACHD mouse brain but had no effect on normal Htt protein levels nor p53 mRNA or protein levels. Expression microarray analysis was employed to determine the effects of wig-1 suppression on genome-wide expression in mouse liver and brain. Reduction of wig-1 caused both down regulation and up regulation of several genes, and a number of wig-1 regulated genes were identified that potentially links wig-1 various signaling pathways and diseases. Conclusion Antisense oligonucleotides can effectively reduce wig-1 levels in mouse liver and brain, which results in specific changes in gene expression for pathways relevant to both the nervous system and cancer.
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Waldvogel HJ, Thu D, Hogg V, Tippett L, Faull RLM. Selective Neurodegeneration, Neuropathology and Symptom Profiles in Huntington’s Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 769:141-52. [DOI: 10.1007/978-1-4614-5434-2_9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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