51
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Identifying therapeutic targets by combining transcriptional data with ordinal clinical measurements. Nat Commun 2017; 8:623. [PMID: 28931805 PMCID: PMC5606996 DOI: 10.1038/s41467-017-00353-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 06/23/2017] [Indexed: 01/05/2023] Open
Abstract
The immense and growing repositories of transcriptional data may contain critical insights for developing new therapies. Current approaches to mining these data largely rely on binary classifications of disease vs. control, and are not able to incorporate measures of disease severity. We report an analytical approach to integrate ordinal clinical information with transcriptomics. We apply this method to public data for a large cohort of Huntington’s disease patients and controls, identifying and prioritizing phenotype-associated genes. We verify the role of a high-ranked gene in dysregulation of sphingolipid metabolism in the disease and demonstrate that inhibiting the enzyme, sphingosine-1-phosphate lyase 1 (SPL), has neuroprotective effects in Huntington’s disease models. Finally, we show that one consequence of inhibiting SPL is intracellular inhibition of histone deacetylases, thus linking our observations in sphingolipid metabolism to a well-characterized Huntington’s disease pathway. Our approach is easily applied to any data with ordinal clinical measurements, and may deepen our understanding of disease processes. Identifying gene subsets affecting disease phenotypes from transcriptome data is challenge. Here, the authors develop a method that combines transcriptional data with disease ordinal clinical measurements to discover a sphingolipid metabolism regulator involving in Huntington’s disease progression.
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52
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Kao YH, Lin MS, Chen CM, Wu YR, Chen HM, Lai HL, Chern Y, Lin CJ. Targeting ENT1 and adenosine tone for the treatment of Huntington's disease. Hum Mol Genet 2017; 26:467-478. [PMID: 28069792 DOI: 10.1093/hmg/ddw402] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 11/21/2016] [Indexed: 11/14/2022] Open
Abstract
Huntington's disease (HD) is caused by an abnormal CAG expansion in the exon 1 of huntingtin gene. The treatment of HD is an unmet medical need. Given the important role of adenosine in modulating brain activity, in this study, levels of adenosine and adenine nucleotides in the cerebral spinal fluid of patients with HD and in the brain of two mouse models of HD (R6/2 and Hdh150Q) were analysed. The expression and activity of ENT1 in the striatum of mice with HD were measured. Targeting adenosine tone for treating HD was examined in R6/2 mice by genetic removal of ENT1 and by giving an ENT1 inhibitor, respectively. The results showed that the adenosine homeostasis is dysregulated in the brain of patients and mice with HD. In patients, the ratio of adenosine/ATP in the cerebral spinal fluid was negatively correlated with the disease duration, and tended to have a positive correlation with independence scale and functional capacity. In comparison to controls, mRNA level of ENT1 was higher in the striatum of R6/2 and Hdh150Q mice. Intrastriatal administration of ENT1 inhibitors increased extracellular level of adenosine in the striatum of R6/2 mice to a much higher level than controls. Chronic inhibition of ENT1 or by genetic removal of ENT1 enhanced the survival of R6/2 mice. Collectively, adenosine homeostasis and ENT1 expression are altered in HD. The inhibition of ENT1 can enhance extracellular adenosine level and be a potential therapeutic approach for treating HD.
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Affiliation(s)
- Yu-Han Kao
- School of Pharmacy, National Taiwan University, Taipei, Taiwan
| | - Meng-Syuan Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chiung-Mei Chen
- Department of Neurology, Chang Gung Memorial Hospital Linkou Medical Center and College of Medicine, Chang-Gung University, Tao-Yuan, Taiwan
| | - Yih-Ru Wu
- Department of Neurology, Chang Gung Memorial Hospital Linkou Medical Center and College of Medicine, Chang-Gung University, Tao-Yuan, Taiwan
| | - Hui-Mei Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Hsing-Lin Lai
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yijuang Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chun-Jung Lin
- School of Pharmacy, National Taiwan University, Taipei, Taiwan
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53
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Chaves G, Özel RE, Rao NV, Hadiprodjo H, Costa YD, Tokuno Z, Pourmand N. Metabolic and transcriptomic analysis of Huntington's disease model reveal changes in intracellular glucose levels and related genes. Heliyon 2017; 3:e00381. [PMID: 28920088 PMCID: PMC5576993 DOI: 10.1016/j.heliyon.2017.e00381] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 07/02/2017] [Accepted: 08/04/2017] [Indexed: 11/19/2022] Open
Abstract
Huntington's Disease (HD) is a neurodegenerative disorder caused by an expansion in a CAG-tri-nucleotide repeat that introduces a poly-glutamine stretch into the huntingtin protein (mHTT). Mutant huntingtin (mHTT) has been associated with several phenotypes including mood disorders and depression. Additionally, HD patients are known to be more susceptible to type II diabetes mellitus (T2DM), and HD mice model develops diabetes. However, the mechanism and pathways that link Huntington's disease and diabetes have not been well established. Understanding the underlying mechanisms can reveal potential targets for drug development in HD. In this study, we investigated the transcriptome of mHTT cell populations alongside intracellular glucose measurements using a functionalized nanopipette. Several genes related to glucose uptake and glucose homeostasis are affected. We observed changes in intracellular glucose concentrations and identified altered transcript levels of certain genes including Sorcs1, Hh-II and Vldlr. Our data suggest that these can be used as markers for HD progression. Sorcs1 may not only have a role in glucose metabolism and trafficking but also in glutamatergic pathways affecting trafficking of synaptic components.
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54
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Du Z, Tertrais M, Courtand G, Leste-Lasserre T, Cardoit L, Masmejean F, Halgand C, Cho YH, Garret M. Differential Alteration in Expression of Striatal GABA AR Subunits in Mouse Models of Huntington's Disease. Front Mol Neurosci 2017; 10:198. [PMID: 28676743 PMCID: PMC5476702 DOI: 10.3389/fnmol.2017.00198] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 06/06/2017] [Indexed: 12/20/2022] Open
Abstract
Huntington’s disease (HD) is a neurodegenerative disorder characterized by progressive motor symptoms that are preceded by cognitive deficits and is considered as a disorder that primarily affects forebrain striatal neurons. To gain a better understanding of the molecular and cellular mechanisms associated with disease progression, we analyzed the expression of proteins involved in GABAergic neurotransmission in the striatum of the R6/1 transgenic mouse model. Western blot, quantitative PCR and immunohistochemical analyses were conducted on male R6/1 mice and age-matched wild type littermates. Analyses were performed on 2 and 6 month-old animals, respectively, before and after the onset of motor symptoms. Expression of GAD 67, GAD 65, NL2, or gephyrin proteins, involved in GABA synthesis or synapse formation did not display major changes. In contrast, expression of α1, α3 and α5 GABAAR subunits was increased while the expression of δ was decreased, suggesting a change in tonic- and phasic inhibitory transmission. Western blot analysis of the striatum from 8 month-old Hdh Q111, a knock-in mouse model of HD with mild deficits, confirmed the α1 subunit increased expression. From immunohistochemical analyses, we also found that α1 subunit expression is increased in medium-sized spiny projection neurons (MSN) and decreased in parvalbumin (PV)-expressing interneurons at 2 and 6 months in R6/1 mice. Moreover, α2 subunit labeling on the PV and MSN cell membranes was increased at 2 months and decreased at 6 months. Alteration of gene expression in the striatum and modification of GABAA receptor subtypes in both interneurons and projection neurons suggested that HD mutation has a profound effect on synaptic plasticity at an early stage, before the onset of motor symptoms. These results also indicate that cognitive and other behavioral deficits may be associated with changes in GABAergic neurotransmission that consequently could be a relevant target for early therapeutic treatment.
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Affiliation(s)
- Zhuowei Du
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, University of BordeauxBordeaux, France.,Centre National de la Recherche Scientifique, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287Bordeaux, France
| | - Margot Tertrais
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, University of BordeauxBordeaux, France.,Centre National de la Recherche Scientifique, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287Bordeaux, France
| | - Gilles Courtand
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, University of BordeauxBordeaux, France.,Centre National de la Recherche Scientifique, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287Bordeaux, France
| | - Thierry Leste-Lasserre
- Institut National de la Santé et de la Recherche Médicale, Neurocentre Magendie, U862, Physiopathologie de la Plasticité NeuronaleBordeaux, France.,Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, University of BordeauxBordeaux, France
| | - Laura Cardoit
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, University of BordeauxBordeaux, France.,Centre National de la Recherche Scientifique, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287Bordeaux, France
| | - Frédérique Masmejean
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, University of BordeauxBordeaux, France.,Centre National de la Recherche Scientifique, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287Bordeaux, France
| | - Christophe Halgand
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, University of BordeauxBordeaux, France.,Centre National de la Recherche Scientifique, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287Bordeaux, France
| | - Yoon H Cho
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, University of BordeauxBordeaux, France.,Centre National de la Recherche Scientifique, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287Bordeaux, France
| | - Maurice Garret
- Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287, University of BordeauxBordeaux, France.,Centre National de la Recherche Scientifique, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, UMR 5287Bordeaux, France
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55
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Baronchelli S, La Spada A, Ntai A, Barbieri A, Conforti P, Jotti GS, Redaelli S, Bentivegna A, De Blasio P, Biunno I. Epigenetic and transcriptional modulation of WDR5, a chromatin remodeling protein, in Huntington's disease human induced pluripotent stem cell (hiPSC) model. Mol Cell Neurosci 2017; 82:46-57. [PMID: 28476540 DOI: 10.1016/j.mcn.2017.04.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 04/04/2017] [Accepted: 04/13/2017] [Indexed: 11/24/2022] Open
Abstract
DNA methylation (DNAm) changes are of increasing relevance to neurodegenerative disorders, including Huntington's disease (HD). We performed genome-wide screening of possible DNAm changes occurring during striatal differentiation in human induced pluripotent stem cells derived from a HD patient (HD-hiPSCs) as cellular model. We identified 240 differentially methylated regions (DMRs) at promoters in fully differentiated HD-hiPSCs. Subsequently, we focused on the methylation differences in a subcluster of genes related to Jumonji Domain Containing 3 (JMJD3), a demethylase that epigenetically regulates neuronal differentiation and activates neuronal progenitor associated genes, which are indispensable for neuronal fate acquisition. Noticeably among these genes, WD repeat-containing protein 5 (WDR5) promoter was found hypermethylated in HD-hiPSCs, resulting in a significant down-modulation in its expression and of the encoded protein. A similar WDR5 expression decrease was seen in a small series of HD-hiPSC lines characterized by different CAG length. The decrease in WDR5 expression was particularly evident in HD-hiPSCs compared to hESCs and control-hiPSCs from healthy subjects. WDR5 is a core component of the MLL/SET1 chromatin remodeling complexes essential for H3K4me3, previously reported to play an important role in stem cells self-renewal and differentiation. These results suggest the existence of epigenetic mechanisms in HD and the identification of genes, which are able to modulate HD phenotype, is important both for biomarker discovery and therapeutic interventions.
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Affiliation(s)
- Simona Baronchelli
- Institute of Genetic and Biomedical Research, National Research Council (IRGB-CNR), via Fantoli 16/15, 20138 Milan, Italy
| | - Alberto La Spada
- Institute of Genetic and Biomedical Research, National Research Council (IRGB-CNR), via Fantoli 16/15, 20138 Milan, Italy
| | - Aikaterini Ntai
- Integrated Systems Engineering Srl, Via Fantoli 16/15, 20138 Milano, Italy
| | - Andrea Barbieri
- Institute of Genetic and Biomedical Research, National Research Council (IRGB-CNR), via Fantoli 16/15, 20138 Milan, Italy
| | - Paola Conforti
- Department of Biosciences, University of Milan and Istituto Nazionale di Genetica Molecolare Padiglione Invernizzi, Via Francesco Sforza 35, 20122 Milan, Italy
| | - Gloria Saccani Jotti
- Department of Biological Science, Biotechnology and Translational - S.Bi.Bi.T., University of Parma, Via Gramsci 14, 43121 Parma, Italy
| | - Serena Redaelli
- Department of Surgery and Translational Medicine, University of Milano-Bicocca, via Cadore 48, 20900 Monza, Milan, Italy
| | - Angela Bentivegna
- Department of Surgery and Translational Medicine, University of Milano-Bicocca, via Cadore 48, 20900 Monza, Milan, Italy; NeuroMI, Milan Center of Neuroscience, via Pergolesi 33, 20900 Monza, Italy
| | - Pasquale De Blasio
- Integrated Systems Engineering Srl, Via Fantoli 16/15, 20138 Milano, Italy
| | - Ida Biunno
- Institute of Genetic and Biomedical Research, National Research Council (IRGB-CNR), via Fantoli 16/15, 20138 Milan, Italy; IRCCS Multimedica, via Fantoli 16/15, 20138 Milano, Italy.
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56
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Hensman Moss DJ, Flower MD, Lo KK, Miller JRC, van Ommen GJB, ’t Hoen PAC, Stone TC, Guinee A, Langbehn DR, Jones L, Plagnol V, van Roon-Mom WMC, Holmans P, Tabrizi SJ. Huntington's disease blood and brain show a common gene expression pattern and share an immune signature with Alzheimer's disease. Sci Rep 2017; 7:44849. [PMID: 28322270 PMCID: PMC5359597 DOI: 10.1038/srep44849] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 02/14/2017] [Indexed: 12/25/2022] Open
Abstract
There is widespread transcriptional dysregulation in Huntington's disease (HD) brain, but analysis is inevitably limited by advanced disease and postmortem changes. However, mutant HTT is ubiquitously expressed and acts systemically, meaning blood, which is readily available and contains cells that are dysfunctional in HD, could act as a surrogate for brain tissue. We conducted an RNA-Seq transcriptomic analysis using whole blood from two HD cohorts, and performed gene set enrichment analysis using public databases and weighted correlation network analysis modules from HD and control brain datasets. We identified dysregulated gene sets in blood that replicated in the independent cohorts, correlated with disease severity, corresponded to the most significantly dysregulated modules in the HD caudate, the most prominently affected brain region, and significantly overlapped with the transcriptional signature of HD myeloid cells. High-throughput sequencing technologies and use of gene sets likely surmounted the limitations of previously inconsistent HD blood expression studies. Our results suggest transcription is disrupted in peripheral cells in HD through mechanisms that parallel those in brain. Immune upregulation in HD overlapped with Alzheimer's disease, suggesting a common pathogenic mechanism involving macrophage phagocytosis and microglial synaptic pruning, and raises the potential for shared therapeutic approaches.
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Affiliation(s)
- Davina J. Hensman Moss
- Department of Neurodegenerative Disease, University College London Institute of Neurology, London, WC1B 5EH, UK
| | - Michael D. Flower
- Department of Neurodegenerative Disease, University College London Institute of Neurology, London, WC1B 5EH, UK
| | - Kitty K. Lo
- University College London Genetics Institute, University College London, London, WC1E 6BT, UK
| | - James R. C. Miller
- Department of Neurodegenerative Disease, University College London Institute of Neurology, London, WC1B 5EH, UK
| | - Gert-Jan B. van Ommen
- Department of Human Genetics, Leiden University Medical Center, Leiden, Postzone S-4-P, The Netherlands
| | - Peter A. C. ’t Hoen
- Department of Human Genetics, Leiden University Medical Center, Leiden, Postzone S-4-P, The Netherlands
| | - Timothy C. Stone
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, CF24 4HQ, UK
| | - Amelia Guinee
- Faculty of Education, University of Cambridge, CB2 8PQ, Cambridge UK
| | - Douglas R. Langbehn
- Departments of Psychiatry and Biostatistics, University of Iowa, IA 52242, USA
| | - Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, CF24 4HQ, UK
| | - Vincent Plagnol
- University College London Genetics Institute, University College London, London, WC1E 6BT, UK
| | | | - Peter Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, CF24 4HQ, UK
| | - Sarah J. Tabrizi
- Department of Neurodegenerative Disease, University College London Institute of Neurology, London, WC1B 5EH, UK
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57
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Ament SA, Pearl JR, Grindeland A, St. Claire J, Earls JC, Kovalenko M, Gillis T, Mysore J, Gusella JF, Lee JM, Kwak S, Howland D, Lee MY, Baxter D, Scherler K, Wang K, Geman D, Carroll JB, MacDonald ME, Carlson G, Wheeler VC, Price ND, Hood LE. High resolution time-course mapping of early transcriptomic, molecular and cellular phenotypes in Huntington's disease CAG knock-in mice across multiple genetic backgrounds. Hum Mol Genet 2017; 26:913-922. [PMID: 28334820 PMCID: PMC6075528 DOI: 10.1093/hmg/ddx006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/09/2016] [Accepted: 01/03/2017] [Indexed: 01/11/2023] Open
Abstract
Huntington's disease is a dominantly inherited neurodegenerative disease caused by the expansion of a CAG repeat in the HTT gene. In addition to the length of the CAG expansion, factors such as genetic background have been shown to contribute to the age at onset of neurological symptoms. A central challenge in understanding the disease progression that leads from the HD mutation to massive cell death in the striatum is the ability to characterize the subtle and early functional consequences of the CAG expansion longitudinally. We used dense time course sampling between 4 and 20 postnatal weeks to characterize early transcriptomic, molecular and cellular phenotypes in the striatum of six distinct knock-in mouse models of the HD mutation. We studied the effects of the HttQ111 allele on the C57BL/6J, CD-1, FVB/NCr1, and 129S2/SvPasCrl genetic backgrounds, and of two additional alleles, HttQ92 and HttQ50, on the C57BL/6J background. We describe the emergence of a transcriptomic signature in HttQ111/+ mice involving hundreds of differentially expressed genes and changes in diverse molecular pathways. We also show that this time course spanned the onset of mutant huntingtin nuclear localization phenotypes and somatic CAG-length instability in the striatum. Genetic background strongly influenced the magnitude and age at onset of these effects. This work provides a foundation for understanding the earliest transcriptional and molecular changes contributing to HD pathogenesis.
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Affiliation(s)
- Seth A. Ament
- Institute for Systems Biology, Seattle, WA, USA
- Institute for Genome Sciences and Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jocelynn R. Pearl
- Institute for Systems Biology, Seattle, WA, USA
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA, USA
| | | | - Jason St. Claire
- Center for Human Genetic Research, Massachusetts General Hospital, Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - John C. Earls
- Institute for Systems Biology, Seattle, WA, USA
- Department of Computer Science, University of Washington, Seattle, WA, USA
| | - Marina Kovalenko
- Center for Human Genetic Research, Massachusetts General Hospital, Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Tammy Gillis
- Center for Human Genetic Research, Massachusetts General Hospital, Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Jayalakshmi Mysore
- Center for Human Genetic Research, Massachusetts General Hospital, Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - James F. Gusella
- Center for Human Genetic Research, Massachusetts General Hospital, Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Jong-Min Lee
- Center for Human Genetic Research, Massachusetts General Hospital, Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Seung Kwak
- CHDI Management/CHDI Foundation, Princeton, NJ, USA
| | | | | | | | | | - Kai Wang
- Institute for Systems Biology, Seattle, WA, USA
| | - Donald Geman
- Department of Applied Mathematics and Statistics, Johns Hopkins University, Baltimore, MD, USA
| | - Jeffrey B. Carroll
- Behavioral Neuroscience Program, Department of Psychology, Western Washington University, Bellingham, WA, USA
| | - Marcy E. MacDonald
- Center for Human Genetic Research, Massachusetts General Hospital, Department of Neurology, Harvard Medical School, Boston, MA, USA
| | | | - Vanessa C. Wheeler
- Center for Human Genetic Research, Massachusetts General Hospital, Department of Neurology, Harvard Medical School, Boston, MA, USA
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58
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Le Gras S, Keime C, Anthony A, Lotz C, De Longprez L, Brouillet E, Cassel JC, Boutillier AL, Merienne K. Altered enhancer transcription underlies Huntington's disease striatal transcriptional signature. Sci Rep 2017; 7:42875. [PMID: 28225006 PMCID: PMC5320509 DOI: 10.1038/srep42875] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 01/16/2017] [Indexed: 01/09/2023] Open
Abstract
Epigenetic and transcriptional alterations are both implicated in Huntington’s disease (HD), a progressive neurodegenerative disease resulting in degeneration of striatal neurons in the brain. However, how impaired epigenetic regulation leads to transcriptional dysregulation in HD is unclear. Here, we investigated enhancer RNAs (eRNAs), a class of long non-coding RNAs transcribed from active enhancers. We found that eRNAs are expressed from many enhancers of mouse striatum and showed that a subset of those eRNAs are deregulated in HD vs control mouse striatum. Enhancer regions producing eRNAs decreased in HD mouse striatum were associated with genes involved in striatal neuron identity. Consistently, they were enriched in striatal super-enhancers. Moreover, decreased eRNA expression in HD mouse striatum correlated with down-regulation of associated genes. Additionally, a significant number of RNA Polymerase II (RNAPII) binding sites were lost within enhancers associated with decreased eRNAs in HD vs control mouse striatum. Together, this indicates that loss of RNAPII at HD mouse enhancers contributes to reduced transcription of eRNAs, resulting in down-regulation of target genes. Thus, our data support the view that eRNA dysregulation in HD striatum is a key mechanism leading to altered transcription of striatal neuron identity genes, through reduced recruitment of RNAPII at super-enhancers.
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Affiliation(s)
- Stéphanie Le Gras
- GenomeEast Platform, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS/INSERM/University of Strasbourg-UMR 7104, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Céline Keime
- GenomeEast Platform, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS/INSERM/University of Strasbourg-UMR 7104, 1 rue Laurent Fries, 67404 Illkirch, France
| | - Anne Anthony
- University of Strasbourg, Laboratory of Cognitive and Adaptive Neurosciences (LNCA), 12 rue Goethe, 67000 Strasbourg, France.,CNRS, LNCA UMR 7364, 12 rue Goethe, 67000 Strasbourg, France
| | - Caroline Lotz
- University of Strasbourg, Laboratory of Cognitive and Adaptive Neurosciences (LNCA), 12 rue Goethe, 67000 Strasbourg, France.,CNRS, LNCA UMR 7364, 12 rue Goethe, 67000 Strasbourg, France
| | - Lucie De Longprez
- Commissariat à l'Energie Atomique (CEA), Département de Recherches Fondamentales (DRF), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), F-92260 Fontenay-aux-Roses, France.,Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, F-92260 Fontenay-aux-Roses, France
| | - Emmanuel Brouillet
- Commissariat à l'Energie Atomique (CEA), Département de Recherches Fondamentales (DRF), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), F-92260 Fontenay-aux-Roses, France.,Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Université Paris-Saclay, UMR 9199, Neurodegenerative Diseases Laboratory, F-92260 Fontenay-aux-Roses, France
| | - Jean-Christophe Cassel
- University of Strasbourg, Laboratory of Cognitive and Adaptive Neurosciences (LNCA), 12 rue Goethe, 67000 Strasbourg, France.,CNRS, LNCA UMR 7364, 12 rue Goethe, 67000 Strasbourg, France
| | - Anne-Laurence Boutillier
- University of Strasbourg, Laboratory of Cognitive and Adaptive Neurosciences (LNCA), 12 rue Goethe, 67000 Strasbourg, France.,CNRS, LNCA UMR 7364, 12 rue Goethe, 67000 Strasbourg, France
| | - Karine Merienne
- University of Strasbourg, Laboratory of Cognitive and Adaptive Neurosciences (LNCA), 12 rue Goethe, 67000 Strasbourg, France.,CNRS, LNCA UMR 7364, 12 rue Goethe, 67000 Strasbourg, France
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59
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Liot G, Valette J, Pépin J, Flament J, Brouillet E. Energy defects in Huntington's disease: Why “in vivo” evidence matters. Biochem Biophys Res Commun 2017; 483:1084-1095. [DOI: 10.1016/j.bbrc.2016.09.065] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 09/13/2016] [Indexed: 01/12/2023]
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60
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Francelle L, Lotz C, Outeiro T, Brouillet E, Merienne K. Contribution of Neuroepigenetics to Huntington's Disease. Front Hum Neurosci 2017; 11:17. [PMID: 28194101 PMCID: PMC5276857 DOI: 10.3389/fnhum.2017.00017] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 01/10/2017] [Indexed: 12/29/2022] Open
Abstract
Unbalanced epigenetic regulation is thought to contribute to the progression of several neurodegenerative diseases, including Huntington’s disease (HD), a genetic disorder considered as a paradigm of epigenetic dysregulation. In this review, we attempt to address open questions regarding the role of epigenetic changes in HD, in the light of recent advances in neuroepigenetics. We particularly discuss studies using genome-wide scale approaches that provide insights into the relationship between epigenetic regulations, gene expression and neuronal activity in normal and diseased neurons, including HD neurons. We propose that cell-type specific techniques and 3D-based methods will advance knowledge of epigenome in the context of brain region vulnerability in neurodegenerative diseases. A better understanding of the mechanisms underlying epigenetic changes and of their consequences in neurodegenerative diseases is required to design therapeutic strategies more effective than current strategies based on histone deacetylase (HDAC) inhibitors. Researches in HD may play a driving role in this process.
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Affiliation(s)
- Laetitia Francelle
- Department of NeuroDegeneration and Restorative Research, University Medical Center Goettingen Goettingen, Germany
| | - Caroline Lotz
- CNRS UMR 7364, Laboratory of Cognitive and Adaptive Neurosciences, University of Strasbourg Strasbourg, France
| | - Tiago Outeiro
- Department of NeuroDegeneration and Restorative Research, University Medical Center Goettingen Goettingen, Germany
| | - Emmanuel Brouillet
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Département de Recherche Fondamentale, Institut d'Imagerie Biomédicale, Molecular Imaging Center, Neurodegenerative diseases Laboratory, UMR 9199, CNRS Université Paris-Sud, Université Paris-Saclay Fontenay-aux-Roses, France
| | - Karine Merienne
- CNRS UMR 7364, Laboratory of Cognitive and Adaptive Neurosciences, University of Strasbourg Strasbourg, France
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61
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Baksi S, Bagh S, Sarkar S, Mukhopadhyay D. Systemic study of a natural feedback loop in Huntington's disease at the onset of neurodegeneration. Biosystems 2016; 150:46-51. [PMID: 27587340 DOI: 10.1016/j.biosystems.2016.08.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 08/09/2016] [Accepted: 08/28/2016] [Indexed: 10/21/2022]
Abstract
Aggregation prone Huntingtin (Htt) protein and its aberrations, causing protein misfolding, have been the prototype of intense research for several decades. Misfolded aggregates or oligomers of different sizes not only deregulate the homeostasis, cellular machinery also counterbalances the effects at least at the initial stages, till the balance tilts towards toxicity and degeneration. In this paper, we combine experimental approaches with system based computational modeling to decipher the molecular mechanisms as well as the hidden dynamics leading to neuronal death in HD. We built an abstracted Boolean gate based electronic circuit that captured the available knowledge and experimental data. We inferred the unknown parameters by simultaneously fitting experimental data generated in both control and perturbed conditions. We demonstrate that, at the initial stages of Htt aggregate formation, individual changes in different protein levels and their interactions in cascade constitute the Grb2-pERK-Foxd3 feedback loop that is sufficient to create Hill-like sensitivity and prevent aggregation to the extent till mutant Htt (mHtt) aggregates become predominant in the cell when they spatially isolate the homeostatic reaction mechanism.
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Affiliation(s)
- Shounak Baksi
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India
| | - Sangram Bagh
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India
| | - Sandip Sarkar
- Applied Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India
| | - Debashis Mukhopadhyay
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India.
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62
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Pan Y, Daito T, Sasaki Y, Chung YH, Xing X, Pondugula S, Swamidass SJ, Wang T, Kim AH, Yano H. Inhibition of DNA Methyltransferases Blocks Mutant Huntingtin-Induced Neurotoxicity. Sci Rep 2016; 6:31022. [PMID: 27516062 PMCID: PMC4981892 DOI: 10.1038/srep31022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 07/13/2016] [Indexed: 02/06/2023] Open
Abstract
Although epigenetic abnormalities have been described in Huntington's disease (HD), the causal epigenetic mechanisms driving neurodegeneration in HD cortex and striatum remain undefined. Using an epigenetic pathway-targeted drug screen, we report that inhibitors of DNA methyltransferases (DNMTs), decitabine and FdCyd, block mutant huntingtin (Htt)-induced toxicity in primary cortical and striatal neurons. In addition, knockdown of DNMT3A or DNMT1 protected neurons against mutant Htt-induced toxicity, together demonstrating a requirement for DNMTs in mutant Htt-triggered neuronal death and suggesting a neurodegenerative mechanism based on DNA methylation-mediated transcriptional repression. Inhibition of DNMTs in HD model primary cortical or striatal neurons restored the expression of several key genes, including Bdnf, an important neurotrophic factor implicated in HD. Accordingly, the Bdnf promoter exhibited aberrant cytosine methylation in mutant Htt-expressing cortical neurons. In vivo, pharmacological inhibition of DNMTs in HD mouse brains restored the mRNA levels of key striatal genes known to be downregulated in HD. Thus, disturbances in DNA methylation play a critical role in mutant Htt-induced neuronal dysfunction and death, raising the possibility that epigenetic strategies targeting abnormal DNA methylation may have therapeutic utility in HD.
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Affiliation(s)
- Yanchun Pan
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Takuji Daito
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yo Sasaki
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yong Hee Chung
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xiaoyun Xing
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Santhi Pondugula
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - S. Joshua Swamidass
- Department of Immunology and Pathology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ting Wang
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Albert H. Kim
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Hope Center for Neurological Disorders Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Hiroko Yano
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
- Hope Center for Neurological Disorders Washington University School of Medicine, St. Louis, MO 63110, USA
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63
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Miller JRC, Lo KK, Andre R, Hensman Moss DJ, Träger U, Stone TC, Jones L, Holmans P, Plagnol V, Tabrizi SJ. RNA-Seq of Huntington's disease patient myeloid cells reveals innate transcriptional dysregulation associated with proinflammatory pathway activation. Hum Mol Genet 2016; 25:2893-2904. [PMID: 27170315 PMCID: PMC5181590 DOI: 10.1093/hmg/ddw142] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/03/2016] [Accepted: 05/03/2016] [Indexed: 12/21/2022] Open
Abstract
Innate immune activation beyond the central nervous system is emerging as a vital component of the pathogenesis of neurodegeneration. Huntington's disease (HD) is a fatal neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin gene. The systemic innate immune system is thought to act as a modifier of disease progression; however, the molecular mechanisms remain only partially understood. Here we use RNA-sequencing to perform whole transcriptome analysis of primary monocytes from thirty manifest HD patients and thirty-three control subjects, cultured with and without a proinflammatory stimulus. In contrast with previous studies that have required stimulation to elicit phenotypic abnormalities, we demonstrate significant transcriptional differences in HD monocytes in their basal, unstimulated state. This includes previously undetected increased resting expression of genes encoding numerous proinflammatory cytokines, such as IL6 Further pathway analysis revealed widespread resting enrichment of proinflammatory functional gene sets, while upstream regulator analysis coupled with Western blotting suggests that abnormal basal activation of the NFĸB pathway plays a key role in mediating these transcriptional changes. That HD myeloid cells have a proinflammatory phenotype in the absence of stimulation is consistent with a priming effect of mutant huntingtin, whereby basal dysfunction leads to an exaggerated inflammatory response once a stimulus is encountered. These data advance our understanding of mutant huntingtin pathogenesis, establish resting myeloid cells as a key source of HD immune dysfunction, and further demonstrate the importance of systemic immunity in the potential treatment of HD and the wider study of neurodegeneration.
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Affiliation(s)
- James R C Miller
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Kitty K Lo
- UCL Genetics Institute, University College London, London, WC1E 6BT, UK
| | - Ralph Andre
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Davina J Hensman Moss
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Ulrike Träger
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Timothy C Stone
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, CF24 4HQ, UK
| | - Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, CF24 4HQ, UK
| | - Peter Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, CF24 4HQ, UK
| | - Vincent Plagnol
- UCL Genetics Institute, University College London, London, WC1E 6BT, UK
| | - Sarah J Tabrizi
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, London, WC1N 3BG, UK
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64
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Mollica PA, Reid JA, Ogle RC, Sachs PC, Bruno RD. DNA Methylation Leads to DNA Repair Gene Down-Regulation and Trinucleotide Repeat Expansion in Patient-Derived Huntington Disease Cells. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:1967-1976. [DOI: 10.1016/j.ajpath.2016.03.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 03/14/2016] [Accepted: 03/16/2016] [Indexed: 12/12/2022]
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65
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Du Z, Chazalon M, Bestaven E, Leste-Lasserre T, Baufreton J, Cazalets JR, Cho YH, Garret M. Early GABAergic transmission defects in the external globus pallidus and rest/activity rhythm alteration in a mouse model of Huntington's disease. Neuroscience 2016; 329:363-79. [PMID: 27217211 DOI: 10.1016/j.neuroscience.2016.05.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 05/12/2016] [Accepted: 05/12/2016] [Indexed: 01/01/2023]
Abstract
Huntington's disease (HD) is characterized by progressive motor symptoms preceded by cognitive deficits and is regarded as a disorder that primarily affects the basal ganglia. The external globus pallidus (GPe) has a central role in the basal ganglia, projects directly to the cortex, and is majorly modulated by GABA. To gain a better understanding of the time course of HD progression and gain insight into the underlying mechanisms, we analyzed GABAergic neurotransmission in the GPe of the R6/1 mouse model at purportedly asymptomatic and symptomatic stages (i.e., 2 and 6months). Western blot and quantitative polymerase chain reaction (PCR) analyses revealed alterations in the GPe of male R6/1 mice compared with wild-type littermates. Expression of proteins involved in pre- and post-synaptic GABAergic compartments as well as synapse number were severely decreased at 2 and 6months. At both ages, patch-clamp electrophysiological recordings showed a decrease of spontaneous and miniature inhibitory post-synaptic currents (IPSCs) suggesting that HD mutation has an early effect on the GABA signaling in the brain. Therefore, we performed continuous locomotor activity recordings from 2 to 4months of age. Actigraphy analyses revealed rest/activity fragmentation alterations that parallel GABAergic system impairment at 2months, while the locomotor deficit is evident only at 3months in R6/1 mice. Our results reveal early deficits in HD and support growing evidence for a critical role played by the GPe in physiological and pathophysiological states. We suggest that actimetry may be used as a non-invasive tool to monitor early disease progression.
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Affiliation(s)
- Zhuowei Du
- Univ. Bordeaux, INCIA, UMR 5287, F-33000 Bordeaux, France; CNRS, INCIA, UMR 5287, F-33000 Bordeaux, France
| | - Marine Chazalon
- Univ. de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France
| | - Emma Bestaven
- Univ. Bordeaux, INCIA, UMR 5287, F-33000 Bordeaux, France; CNRS, INCIA, UMR 5287, F-33000 Bordeaux, France
| | - Thierry Leste-Lasserre
- INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France; University of Bordeaux, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, F-33000 Bordeaux, France
| | - Jérôme Baufreton
- Univ. de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, F-33000 Bordeaux, France
| | - Jean-René Cazalets
- Univ. Bordeaux, INCIA, UMR 5287, F-33000 Bordeaux, France; CNRS, INCIA, UMR 5287, F-33000 Bordeaux, France
| | - Yoon H Cho
- Univ. Bordeaux, INCIA, UMR 5287, F-33000 Bordeaux, France; CNRS, INCIA, UMR 5287, F-33000 Bordeaux, France
| | - Maurice Garret
- Univ. Bordeaux, INCIA, UMR 5287, F-33000 Bordeaux, France; CNRS, INCIA, UMR 5287, F-33000 Bordeaux, France.
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66
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Fang F, Peng T, Yang S, Wang W, Zhang Y, Li H. Lycium barbarum
polysaccharide attenuates the cytotoxicity of mutant huntingtin and increases the activity of AKT. Int J Dev Neurosci 2016; 52:66-74. [DOI: 10.1016/j.ijdevneu.2016.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 05/02/2016] [Accepted: 05/02/2016] [Indexed: 01/13/2023] Open
Affiliation(s)
- Fang Fang
- Division of Histology and EmbryologyDepartment of AnatomyTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030People's Republic of China
| | - Ting Peng
- Division of Histology and EmbryologyDepartment of AnatomyTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030People's Republic of China
- Institute for Brain SciencesTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030People's Republic of China
- Collaborative Innovation Center for Brain ScienceHuazhong University of Science and TechnologyWuhan430030People's Republic of China
| | - Shiming Yang
- Division of Histology and EmbryologyDepartment of AnatomyTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030People's Republic of China
| | - Weixi Wang
- Division of Histology and EmbryologyDepartment of AnatomyTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030People's Republic of China
| | - Yinong Zhang
- Division of Histology and EmbryologyDepartment of AnatomyTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030People's Republic of China
| | - He Li
- Division of Histology and EmbryologyDepartment of AnatomyTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030People's Republic of China
- Institute for Brain SciencesTongji Medical CollegeHuazhong University of Science and TechnologyWuhan430030People's Republic of China
- Collaborative Innovation Center for Brain ScienceHuazhong University of Science and TechnologyWuhan430030People's Republic of China
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67
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Kumar A, Zhang J, Tallaksen-Greene S, Crowley MR, Crossman DK, Morton AJ, Van Groen T, Kadish I, Albin RL, Lesort M, Detloff PJ. Allelic series of Huntington's disease knock-in mice reveals expression discorrelates. Hum Mol Genet 2016; 25:1619-36. [PMID: 26908599 DOI: 10.1093/hmg/ddw040] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 02/08/2016] [Indexed: 11/13/2022] Open
Abstract
Identifying molecular drivers of pathology provides potential therapeutic targets. Differentiating between drivers and coincidental molecular alterations presents a major challenge. Variation unrelated to pathology further complicates transcriptomic, proteomic and metabolomic studies which measure large numbers of individual molecules. To overcome these challenges towards the goal of determining drivers of Huntington's disease (HD), we generated an allelic series of HD knock-in mice with graded levels of phenotypic severity for comparison with molecular alterations. RNA-sequencing analysis of this series reveals high numbers of transcripts with level alterations that do not correlate with phenotypic severity. These discorrelated molecular changes are unlikely to be drivers of pathology allowing an exclusion-based strategy to provide a short list of driver candidates. Further analysis of the data shows that a majority of transcript level changes in HD knock-in mice involve alteration of the rate of mRNA processing and/or degradation rather than solely being due to alteration of transcription rate. The overall strategy described can be applied to assess the influence of any molecular change on pathology for diseases where different mutations cause graded phenotypic severity.
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Affiliation(s)
- Ashish Kumar
- Department of Cell, Developmental and Integrative Biology
| | | | - Sara Tallaksen-Greene
- VAAAHS GRECC, Ann Arbor, MI, USA and Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | | | - A Jennifer Morton
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | | | - Inga Kadish
- Department of Cell, Developmental and Integrative Biology
| | - Roger L Albin
- VAAAHS GRECC, Ann Arbor, MI, USA and Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Mathieu Lesort
- Department of Psychiatry, University of Alabama at Birmingham, Birmingham, AL, USA
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68
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Merienne K, Boutillier AL. [Epigenetic regulations and cerebral plasticity: towards new therapeutic options in neurodegenerative diseases?]. Biol Aujourdhui 2016; 210:297-309. [PMID: 28327286 DOI: 10.1051/jbio/2017002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Indexed: 11/15/2022]
Abstract
Although revealed in the 1950's, epigenetics is still a fast-growing field. Its delineations continuously evolve and become clarified. In particular, "neuroepigenetics", a notion that encompasses epigenetic regulations associated with neuronal processes, appears very promising. Indeed, the challenge to be undertaken in this sub-field is double. On the one hand, it should bring molecular comprehension of specific neuronal processes, some of them falling within the long term regulations, such as learning and memory. On the other hand, it could bring therapeutic options for brain diseases, e.g. neurodegenerative diseases such as Alzheimer's or Huntington's diseases.
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69
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Nageshwaran S, Festenstein R. Epigenetics and Triplet-Repeat Neurological Diseases. Front Neurol 2015; 6:262. [PMID: 26733936 PMCID: PMC4685448 DOI: 10.3389/fneur.2015.00262] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 11/30/2015] [Indexed: 01/15/2023] Open
Abstract
The term "junk DNA" has been reconsidered following the delineation of the functional significance of repetitive DNA regions. Typically associated with centromeres and telomeres, DNA repeats are found in nearly all organisms throughout their genomes. Repetitive regions are frequently heterochromatinized resulting in silencing of intrinsic and nearby genes. However, this is not a uniform rule, with several genes known to require such an environment to permit transcription. Repetitive regions frequently exist as dinucleotide, trinucleotide, and tetranucleotide repeats. The association between repetitive regions and disease was emphasized following the discovery of abnormal trinucleotide repeats underlying spinal and bulbar muscular atrophy (Kennedy's disease) and fragile X syndrome of mental retardation (FRAXA) in 1991. In this review, we provide a brief overview of epigenetic mechanisms and then focus on several diseases caused by DNA triplet-repeat expansions, which exhibit diverse epigenetic effects. It is clear that the emerging field of epigenetics is already generating novel potential therapeutic avenues for this group of largely incurable diseases.
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Affiliation(s)
- Sathiji Nageshwaran
- Division of Brain Sciences and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus , London , UK
| | - Richard Festenstein
- Division of Brain Sciences and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus , London , UK
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70
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Choudhury KR, Das S, Bhattacharyya NP. Differential proteomic and genomic profiling of mouse striatal cell model of Huntington's disease and control; probable implications to the disease biology. J Proteomics 2015; 132:155-66. [PMID: 26581643 DOI: 10.1016/j.jprot.2015.11.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 09/16/2015] [Accepted: 11/11/2015] [Indexed: 10/22/2022]
Abstract
UNLABELLED Huntington's disease (HD) is an autosomal dominant disorder of central nervous system caused by expansion of CAG repeats in exon1 of the huntingtin gene (Htt). Among various dysfunctions originated from the mutation in Htt gene, transcriptional deregulation has been considered to be one of the most important abnormalities. Large numbers of investigations identified altered expressions of genes in brains of HD patients and many models of HD. In this study we employed 2D SDS-PAGE/MALDI-MS coupled with 2D-DIGE and real-time PCR experiments of an array of genes focused to HD pathway to determine altered protein and gene expressions in STHdh(Q111)/Hdh(Q111) cells, a cell model of HD and compared with STHdh(Q7)/Hdh(Q7) cells, its wild type counterpart. We annotated 76 proteins from these cells and observed differential expressions of 31 proteins (by 2D-DIGE) involved in processes like unfolded protein binding, negative regulation of neuron apoptosis, response to superoxides etc. Our PCR array experiments identified altered expressions of 47 genes. Altogether significant alteration of 77 genes/proteins could be identified in this HD cell line with potential relevance to HD biology. BIOLOGICAL SIGNIFICANCE In this study we intended to find out differential proteomic and genomic profiles in HD condition. We used the STHdh cells, a cellular model for HD and control. These are mouse striatal neuronal cell lines harboring 7 and 111 knock-in CAG repeats in their two alleles. The 111Q containing cell line (STHdh(Q111)/Hdh(Q111)) mimics diseased condition, whereas the 7Q containing ones (STHdh(Q7)/Hdh(Q7)), serves as the proper control cell line. Proteomic experiments were performed earlier to obtain differential expressions of proteins in R6/2 mice models, Hdh(Q) knock-in mice and in plasma and CSF from HD patients. However, no earlier report on proteomic alterations in these two HD cell lines and control was available in literature. It was, therefore, an important objective to find out differential expressions of proteins in these two cell lines. In this study, we annotated 76 proteins from STHdh(Q7)/Hdh(Q7) and STHdh(Q111)/Hdh(Q111) cells using 2D-gel/mass spectrometry. Next, by performing 2D-DIGE, we observed differential expressions of 31 proteins (16 upregulated and 15 downregulated) between these two cell lines. We also performed customized qRT-PCR array focused to HD pathway and found differential expressions of 47 genes (8 gene expressions increased and 39 genes were decreased significantly). A total of 77 genes/proteins (Htt downregulated in both the studies) were found to be significantly altered from both the experimental paradigms. We validated the differential expressions of Vim, Hypk, Ran, Dstn, Hspa5 and Sod2 either by qRT-PCR or Western blot analysis or both. Out of these 77, similar trends in alteration of 19 out of 31 and 38 out of 47 proteins/genes were reported in earlier studies. Thus our study confirmed earlier observations on differential gene/protein expressions in HD and are really useful. Additionally, we observed differential expression of some novel genes/proteins. One of this was Hypk, a Htt-interacting chaperone protein with the ability to solubilize mHtt aggregated structures in cell lines. We propose that downregulation of Hypk in STHdh(Q111)/Hdh(Q111) has a causal effect towards HD pathogenesis. Thus the novel findings from our study need further research and might be helpful to understand the molecular mechanism behind HD pathogenesis.
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Affiliation(s)
- Kamalika Roy Choudhury
- Crystallography & Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.
| | - Srijit Das
- Crystallography & Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.
| | - Nitai P Bhattacharyya
- Crystallography & Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.
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Ramsingh AI, Manley K, Rong Y, Reilly A, Messer A. Transcriptional dysregulation of inflammatory/immune pathways after active vaccination against Huntington's disease. Hum Mol Genet 2015; 24:6186-97. [PMID: 26307082 PMCID: PMC4599676 DOI: 10.1093/hmg/ddv335] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 08/04/2015] [Accepted: 08/10/2015] [Indexed: 01/01/2023] Open
Abstract
Immunotherapy, both active and passive, is increasingly recognized as a powerful approach to a wide range of diseases, including Alzheimer's and Parkinson's. Huntington's disease (HD), an autosomal dominant disorder triggered by misfolding of huntingtin (HTT) protein with an expanded polyglutamine tract, could also benefit from this approach. Individuals can be identified genetically at the earliest stages of disease, and there may be particular benefits to a therapy that can target peripheral tissues in addition to brain. In this active vaccination study, we first examined safety and immunogenicity for a broad series of peptide, protein and DNA plasmid immunization protocols, using fragment (R6/1), and knock-in (zQ175) models. No safety issues were found. The strongest and most uniform immune response was to a combination of three non-overlapping HTT Exon1 coded peptides, conjugated to KLH, delivered with alum adjuvant. An N586-82Q plasmid, delivered via gene gun, also showed ELISA responses, mainly in the zQ175 strain, but with more variability, and less robust responses in HD compared with wild-type controls. Transcriptome profiling of spleens from the triple peptide-immunized cohort showed substantial HD-specific differences including differential activation of genes associated with innate immune responses, absence of negative feedback control of gene expression by regulators, a temporal dysregulation of innate immune responses and transcriptional repression of genes associated with memory T cell responses. These studies highlight critical issues for immunotherapy and HD disease management in general.
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Affiliation(s)
- Arlene I Ramsingh
- New York State Department of Health, Wadsworth Center, Albany, NY, USA and
| | - Kevin Manley
- New York State Department of Health, Wadsworth Center, Albany, NY, USA and
| | - Yinghui Rong
- New York State Department of Health, Wadsworth Center, Albany, NY, USA and
| | - Andrew Reilly
- New York State Department of Health, Wadsworth Center, Albany, NY, USA and
| | - Anne Messer
- New York State Department of Health, Wadsworth Center, Albany, NY, USA and Neural Stem Cell Institute, Regenerative Research Foundation, Rensselaer, NY, USA
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72
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Bucha S, Mukhopadhyay D, Bhattacharyya NP. Regulation of mitochondrial morphology and cell cycle by microRNA-214 targeting Mitofusin2. Biochem Biophys Res Commun 2015; 465:797-802. [DOI: 10.1016/j.bbrc.2015.08.090] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 08/20/2015] [Indexed: 11/15/2022]
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73
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Sharma S, Taliyan R. Transcriptional dysregulation in Huntington's disease: The role of histone deacetylases. Pharmacol Res 2015; 100:157-69. [PMID: 26254871 DOI: 10.1016/j.phrs.2015.08.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 08/03/2015] [Accepted: 08/03/2015] [Indexed: 12/16/2022]
Abstract
Huntington's disease (HD) is a progressive neurological disorder for which there are no disease-modifying treatments. Although, the exact underlying mechanism(s) leading to the neural cell death in HD still remains elusive, the transcriptional dysregulation is a major molecular feature. Recently, the transcriptional activation and repression regulated by chromatin acetylation has been found to be impaired in HD pathology. The acetylation and deacetylation of histone proteins is carried out by opposing actions of histone acetyl-transferases and histone deacetylases (HDACs), respectively. Studies carried out in cell culture, yeast, Drosophila and rodent model(s) have indicated that HDAC inhibitors (HDACIs) might provide useful class of therapeutic agents for HD. Clinical trials have also reported the beneficial effects of HDACIs in patients suffering from HD. Therefore, the development of HDACIs as therapeutics for HD has been vigorously pursued. In this review, we highlight and summarize the putative role of HDACs in HD like pathology and further discuss the potential of HDACIs as new therapeutic avenues for the treatment of HD.
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Affiliation(s)
- Sorabh Sharma
- Neuropharmacology Division, Department of Pharmacy Birla Institute of Technology and Science, Pilani 333031, Rajasthan, India.
| | - Rajeev Taliyan
- Neuropharmacology Division, Department of Pharmacy Birla Institute of Technology and Science, Pilani 333031, Rajasthan, India
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Bates GP, Dorsey R, Gusella JF, Hayden MR, Kay C, Leavitt BR, Nance M, Ross CA, Scahill RI, Wetzel R, Wild EJ, Tabrizi SJ. Huntington disease. Nat Rev Dis Primers 2015; 1:15005. [PMID: 27188817 DOI: 10.1038/nrdp.2015.5] [Citation(s) in RCA: 911] [Impact Index Per Article: 101.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Huntington disease is devastating to patients and their families - with autosomal dominant inheritance, onset typically in the prime of adult life, progressive course, and a combination of motor, cognitive and behavioural features. The disease is caused by an expanded CAG trinucleotide repeat (of variable length) in HTT, the gene that encodes the protein huntingtin. In mutation carriers, huntingtin is produced with abnormally long polyglutamine sequences that confer toxic gains of function and predispose the protein to fragmentation, resulting in neuronal dysfunction and death. In this Primer, we review the epidemiology of Huntington disease, noting that prevalence is higher than previously thought, geographically variable and increasing. We describe the relationship between CAG repeat length and clinical phenotype, as well as the concept of genetic modifiers of the disease. We discuss normal huntingtin protein function, evidence for differential toxicity of mutant huntingtin variants, theories of huntingtin aggregation and the many different mechanisms of Huntington disease pathogenesis. We describe the genetic and clinical diagnosis of the condition, its clinical assessment and the multidisciplinary management of symptoms, given the absence of effective disease-modifying therapies. We review past and present clinical trials and therapeutic strategies under investigation, including impending trials of targeted huntingtin-lowering drugs and the progress in development of biomarkers that will support the next generation of trials. For an illustrated summary of this Primer, visit: http://go.nature.com/hPMENh.
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Affiliation(s)
- Gillian P Bates
- Department of Medical and Molecular Genetics, King's College London, London, UK
| | - Ray Dorsey
- Department of Neurology, University of Rochester Medical Center, Rochester, New York, USA
| | - James F Gusella
- Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, and Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Chris Kay
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Blair R Leavitt
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Martha Nance
- Struthers Parkinson's Center, Golden Valley, Minneapolis, Minnesota, USA; and Hennepin County Medical Center, Minneapolis, Minnesota, USA
| | - Christopher A Ross
- Division of Neurobiology, Department of Psychiatry and Departments of Neurology, Pharmacology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Rachael I Scahill
- Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Ronald Wetzel
- Department of Structural Biology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Edward J Wild
- Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Sarah J Tabrizi
- Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
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Achour M, Le Gras S, Keime C, Parmentier F, Lejeune FX, Boutillier AL, Neri C, Davidson I, Merienne K. Neuronal identity genes regulated by super-enhancers are preferentially down-regulated in the striatum of Huntington's disease mice. Hum Mol Genet 2015; 24:3481-96. [DOI: 10.1093/hmg/ddv099] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 03/13/2015] [Indexed: 12/20/2022] Open
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76
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The Emerging Role of MitomiRs in the Pathophysiology of Human Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 888:123-54. [DOI: 10.1007/978-3-319-22671-2_8] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Striatal long noncoding RNA Abhd11os is neuroprotective against an N-terminal fragment of mutant huntingtin in vivo. Neurobiol Aging 2014; 36:1601.e7-16. [PMID: 25619660 DOI: 10.1016/j.neurobiolaging.2014.11.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 10/28/2014] [Accepted: 11/25/2014] [Indexed: 12/26/2022]
Abstract
A large number of gene products that are enriched in the striatum have ill-defined functions, although they may have key roles in age-dependent neurodegenerative diseases affecting the striatum, especially Huntington disease (HD). In the present study, we focused on Abhd11os, (called ABHD11-AS1 in human) which is a putative long noncoding RNA (lncRNA) whose expression is enriched in the mouse striatum. We confirm that despite the presence of 2 small open reading frames (ORFs) in its sequence, Abhd11os is not translated into a detectable peptide in living cells. We demonstrate that Abhd11os levels are markedly reduced in different mouse models of HD. We performed in vivo experiments in mice using lentiviral vectors encoding either Abhd11os or a small hairpin RNA targeting Abhd11os. Results show that Abhd11os overexpression produces neuroprotection against an N-terminal fragment of mutant huntingtin, whereas Abhd11os knockdown is protoxic. These novel results indicate that the loss lncRNA Abhd11os likely contribute to striatal vulnerability in HD. Our study emphasizes that lncRNA may play crucial roles in neurodegenerative diseases.
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Francelle L, Galvan L, Gaillard MC, Guillermier M, Houitte D, Bonvento G, Petit F, Jan C, Dufour N, Hantraye P, Elalouf JM, De Chaldée M, Déglon N, Brouillet E. Loss of the thyroid hormone-binding protein Crym renders striatal neurons more vulnerable to mutant huntingtin in Huntington's disease. Hum Mol Genet 2014; 24:1563-73. [PMID: 25398949 PMCID: PMC4381754 DOI: 10.1093/hmg/ddu571] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The mechanisms underlying preferential atrophy of the striatum in Huntington's disease (HD) are unknown. One hypothesis is that a set of gene products preferentially expressed in the striatum could determine the particular vulnerability of this brain region to mutant huntingtin (mHtt). Here, we studied the striatal protein µ-crystallin (Crym). Crym is the NADPH-dependent p38 cytosolic T3-binding protein (p38CTBP), a key regulator of thyroid hormone (TH) T3 (3,5,3'-triiodo-l-thyronine) transportation. It has been also recently identified as the enzyme that reduces the sulfur-containing cyclic ketimines, which are potential neurotransmitters. Here, we confirm the preferential expression of the Crym protein in the rodent and macaque striatum. Crym expression was found to be higher in the macaque caudate than in the putamen. Expression of Crym was reduced in the BACHD and Knock-in 140CAG mouse models of HD before onset of striatal atrophy. We show that overexpression of Crym in striatal medium-size spiny neurons using a lentiviral-based strategy in mice is neuroprotective against the neurotoxicity of an N-terminal fragment of mHtt in vivo. Thus, reduction of Crym expression in HD could render striatal neurons more susceptible to mHtt suggesting that Crym may be a key determinant of the vulnerability of the striatum. In addition our work points to Crym as a potential molecular link between striatal degeneration and the THs deregulation reported in HD patients.
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Affiliation(s)
- Laetitia Francelle
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France
| | - Laurie Galvan
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France
| | - Marie-Claude Gaillard
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France
| | - Martine Guillermier
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France
| | - Diane Houitte
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France
| | - Gilles Bonvento
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France
| | - Fanny Petit
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France
| | - Caroline Jan
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France
| | - Noëlle Dufour
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France
| | - Philippe Hantraye
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France
| | - Jean-Marc Elalouf
- CEA, iBiTecS, F-91191 Gif-sur-Yvette Cedex, France, CNRS, FRE 3377, F-91191 Gif-sur-Yvette Cedex, France, Université Paris-Sud, FRE 3377, F-91191 Gif-sur-Yvette Cedex, France
| | - Michel De Chaldée
- CEA, iBiTecS, F-91191 Gif-sur-Yvette Cedex, France, CNRS, FRE 3377, F-91191 Gif-sur-Yvette Cedex, France, Université Paris-Sud, FRE 3377, F-91191 Gif-sur-Yvette Cedex, France
| | - Nicole Déglon
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France, Laboratory of Cellular and Molecular Neurotherapies, Department of Clinical Neurociences, Lausanne University Hospital, Lausanne, Switzerland
| | - Emmanuel Brouillet
- CEA, DSV, I²BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France, Neurodegenerative Diseases Laboratory, CNRS CEA URA 2210, F-92265 Fontenay-aux-Roses, France,
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Liu KY, Shyu YC, Barbaro BA, Lin YT, Chern Y, Thompson LM, James Shen CK, Marsh JL. Disruption of the nuclear membrane by perinuclear inclusions of mutant huntingtin causes cell-cycle re-entry and striatal cell death in mouse and cell models of Huntington's disease. Hum Mol Genet 2014; 24:1602-16. [PMID: 25398943 DOI: 10.1093/hmg/ddu574] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Accumulation of N-terminal fragments of mutant huntingtin (mHTT) in the cytoplasm, nuclei and axons of neurons is a hallmark of Huntington's disease (HD), although how these fragments negatively impact neurons remains unclear. We followed the distribution of mHTT in the striata of transgenic R6/2-J2 HD mice as their motor function declined. The fraction of cells with diffuse, perinuclear or intranuclear mHTT changed in parallel with decreasing motor function. In transgenic mice, medium spiny neurons (MSNs) that exhibited perinuclear inclusions expressed cell-cycle markers typically not seen in the striata of normal mice, and these cells are preferentially lost as disease progresses. Electron microscopy reveals that perinuclear inclusions disrupt the nuclear envelope. The progression of perinuclear inclusions being accompanied by cell-cycle activation and culminating in cell death was also observed in 1° cortical neurons. These observations provide a strong correlation between the subcellular location of mHTT, disruption of the nucleus, re-entry into the cell-cycle and eventual neuronal death. They also highlight the fact that the subcellular distribution of mHTT is highly dynamic such that the distribution of mHTT observed depends greatly on the stage of the disease being examined.
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Affiliation(s)
- Kuan-Yu Liu
- Department of Life Sciences and Institute of Genome Sciences and Institute of Molecular Biology and
| | - Yu-Chiau Shyu
- VYM Genome Research Center, National Yang-Ming University, Taipei 112, Taiwan, Institute of Molecular Biology and
| | - Brett A Barbaro
- Developmental Biology Center, Department of Developmental and Cell Biology
| | | | - Yijuang Chern
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei 115, Taiwan, ROC
| | - Leslie Michels Thompson
- Department of Psychiatry and Human Behavior, Department of Neurobiology and Behavior, University of California, Irvine, CA 92697, USA
| | - Che-Kun James Shen
- Department of Life Sciences and Institute of Genome Sciences and Institute of Molecular Biology and
| | - J Lawrence Marsh
- Developmental Biology Center, Department of Developmental and Cell Biology
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80
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McQuade LR, Balachandran A, Scott HA, Khaira S, Baker MS, Schmidt U. Proteomics of Huntington's disease-affected human embryonic stem cells reveals an evolving pathology involving mitochondrial dysfunction and metabolic disturbances. J Proteome Res 2014; 13:5648-59. [PMID: 25316320 DOI: 10.1021/pr500649m] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by a mutation in the Huntingtin gene, where excessive (≥ 36) CAG repeats encode for glutamine expansion in the huntingtin protein. Research using mouse models and human pathological material has indicated dysfunctions in a myriad of systems, including mitochondrial and ubiquitin/proteasome complexes, cytoskeletal transport, signaling, and transcriptional regulation. Here, we examined the earliest biochemical and pathways involved in HD pathology. We conducted a proteomics study combined with immunocytochemical analysis of undifferentiated HD-affected and unaffected human embryonic stem cells (hESC). Analysis of 1883 identifications derived from membrane and cytosolic enriched fractions revealed mitochondria as the primary dysfunctional organ in HD-affected pluripotent cells in the absence of significant differences in huntingtin protein. Furthermore, on the basis of analysis of 645 proteins found in neurodifferentiated hESC, we show a shift to transcriptional dysregulation and cytoskeletal abnormalities as the primary pathologies in HD-affected cells differentiating along neural lineages in vitro. We also show this is concomitant with an up-regulation in expression of huntingtin protein in HD-affected cells. This study demonstrates the utility of a model that recapitulates HD pathology and offers insights into disease initiation, etiology, progression, and potential therapeutic intervention.
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Affiliation(s)
- Leon R McQuade
- Australian Proteome Analysis Facility, §Australian School of Advanced Medicine, Macquarie University , Sydney, New South Wales 2109, Australia
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81
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Ramani B, Harris GM, Huang R, Seki T, Murphy GG, Costa MDC, Fischer S, Saunders TL, Xia G, McEachin RC, Paulson HL. A knockin mouse model of spinocerebellar ataxia type 3 exhibits prominent aggregate pathology and aberrant splicing of the disease gene transcript. Hum Mol Genet 2014; 24:1211-24. [PMID: 25320121 DOI: 10.1093/hmg/ddu532] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Polyglutamine diseases, including spinocerebellar ataxia type 3 (SCA3), are caused by CAG repeat expansions that encode abnormally long glutamine repeats in the respective disease proteins. While the mechanisms underlying neurodegeneration remain uncertain, evidence supports a proteotoxic role for the mutant protein dictated in part by the specific genetic and protein context. To further define pathogenic mechanisms in SCA3, we generated a mouse model in which a CAG expansion of 82 repeats was inserted into the murine locus by homologous recombination. SCA3 knockin mice exhibit region-specific aggregate pathology marked by intranuclear accumulation of the mutant Atxn3 protein, abundant nuclear inclusions and, in select brain regions, extranuclear aggregates localized to neuritic processes. Knockin mice also display altered splicing of the disease gene, promoting expression of an alternative isoform in which the intron immediately downstream of the CAG repeat is retained. In an independent mouse model expressing the full human ATXN3 disease gene, expression of this alternatively spliced transcript is also enhanced. These results, together with recent findings in other polyglutamine diseases, suggest that CAG repeat expansions can promote aberrant splicing to produce potentially more aggregate-prone isoforms of the disease proteins. This report of a SCA3 knockin mouse expands the repertoire of existing models of SCA3, and underscores the potential contribution of alternative splicing to disease pathogenesis in SCA3 and other polyglutamine disorders.
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Affiliation(s)
- Biswarathan Ramani
- Department of Neurology, Medical Scientist Training Program and Neuroscience Graduate Program
| | - Ginny M Harris
- Medical Scientist Training and Cellular and Molecular Biology Graduate Programs, University of Iowa College of Medicine, IA, USA
| | | | | | | | | | | | | | - Guangbin Xia
- Department of Neurology, University of Florida, Gainesville, FL, USA
| | - Richard C McEachin
- Department of Computational Medicine & Bioinformatics, University of Michigan, MI, USA
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82
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Kurosawa M, Matsumoto G, Kino Y, Okuno M, Kurosawa-Yamada M, Washizu C, Taniguchi H, Nakaso K, Yanagawa T, Warabi E, Shimogori T, Sakurai T, Hattori N, Nukina N. Depletion of p62 reduces nuclear inclusions and paradoxically ameliorates disease phenotypes in Huntington's model mice. Hum Mol Genet 2014; 24:1092-105. [PMID: 25305080 DOI: 10.1093/hmg/ddu522] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Huntington's disease (HD) is a dominantly inherited genetic disease caused by mutant huntingtin (htt) protein with expanded polyglutamine (polyQ) tracts. A neuropathological hallmark of HD is the presence of neuronal inclusions of mutant htt. p62 is an important regulatory protein in selective autophagy, a process by which aggregated proteins are degraded, and it is associated with several neurodegenerative disorders including HD. Here, we investigated the effect of p62 depletion in three HD model mice: R6/2, HD190QG and HD120QG mice. We found that loss of p62 in these models led to longer life spans and reduced nuclear inclusions, although cytoplasmic inclusions increased with polyQ length. In mouse embryonic fibroblasts (MEFs) with or without p62, mutant htt with a nuclear localization signal (NLS) showed no difference in nuclear inclusion between the two MEF types. In the case of mutant htt without NLS, however, p62 depletion increased cytoplasmic inclusions. Furthermore, to examine the effect of impaired autophagy in HD model mice, we crossed R6/2 mice with Atg5 conditional knockout mice. These mice also showed decreased nuclear inclusions and increased cytoplasmic inclusions, similar to HD mice lacking p62. These data suggest that the genetic ablation of p62 in HD model mice enhances cytoplasmic inclusion formation by interrupting autophagic clearance of polyQ inclusions. This reduces polyQ nuclear influx and paradoxically ameliorates disease phenotypes by decreasing toxic nuclear inclusions.
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Affiliation(s)
- Masaru Kurosawa
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan, Laboratory for Structural Neuropathology, Laboratory for Molecular Mechanisms of Thalamus Development, RIKEN Brain Science Institute, Saitama 351-0198, Japan, CREST (Core Research for Evolutionary Science and Technology), JST, Tokyo 102-0076, Japan
| | - Gen Matsumoto
- Department of Neuroscience for Neurodegenerative Disorders, Laboratory for Structural Neuropathology, Laboratory for Molecular Mechanisms of Thalamus Development, RIKEN Brain Science Institute, Saitama 351-0198, Japan, CREST (Core Research for Evolutionary Science and Technology), JST, Tokyo 102-0076, Japan
| | - Yoshihiro Kino
- Department of Neuroscience for Neurodegenerative Disorders, Laboratory for Structural Neuropathology, Laboratory for Molecular Mechanisms of Thalamus Development, RIKEN Brain Science Institute, Saitama 351-0198, Japan, CREST (Core Research for Evolutionary Science and Technology), JST, Tokyo 102-0076, Japan
| | | | | | | | - Harumi Taniguchi
- Department of Neuroscience for Neurodegenerative Disorders, Laboratory for Structural Neuropathology, Laboratory for Molecular Mechanisms of Thalamus Development, RIKEN Brain Science Institute, Saitama 351-0198, Japan
| | - Kazuhiro Nakaso
- Department of Neurology, Institute of Neurological Sciences, Faculty of Medicine, Tottori University, Tottori 683-8504, Japan
| | - Toru Yanagawa
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba 305-8575, Japan and
| | - Eiji Warabi
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba 305-8575, Japan and
| | - Tomomi Shimogori
- Laboratory for Molecular Mechanisms of Thalamus Development, RIKEN Brain Science Institute, Saitama 351-0198, Japan
| | - Takashi Sakurai
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | | | - Nobuyuki Nukina
- Department of Neuroscience for Neurodegenerative Disorders, Laboratory for Structural Neuropathology, Laboratory for Molecular Mechanisms of Thalamus Development, RIKEN Brain Science Institute, Saitama 351-0198, Japan, CREST (Core Research for Evolutionary Science and Technology), JST, Tokyo 102-0076, Japan
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83
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Barbaro BA, Lukacsovich T, Agrawal N, Burke J, Bornemann DJ, Purcell JM, Worthge SA, Caricasole A, Weiss A, Song W, Morozova OA, Colby DW, Marsh JL. Comparative study of naturally occurring huntingtin fragments in Drosophila points to exon 1 as the most pathogenic species in Huntington's disease. Hum Mol Genet 2014; 24:913-25. [PMID: 25305076 DOI: 10.1093/hmg/ddu504] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Although Huntington's disease is caused by the expansion of a CAG triplet repeat within the context of the 3144-amino acid huntingtin protein (HTT), studies reveal that N-terminal fragments of HTT containing the expanded PolyQ region can be produced by proteolytic processing and/or aberrant splicing. N-terminal HTT fragments are also prevalent in postmortem tissue, and expression of some of these fragments in model organisms can cause pathology. This has led to the hypothesis that N-terminal peptides may be critical modulators of disease pathology, raising the possibility that targeting aberrant splicing or proteolytic processing may present attractive therapeutic targets. However, many factors can contribute to pathology, including genetic background and differential expression of transgenes, in addition to intrinsic differences between fragments and their cellular effects. We have used Drosophila as a model system to determine the relative toxicities of different naturally occurring huntingtin fragments in a system in which genetic background, transgene expression levels and post-translational proteolytic processing can be controlled. These studies reveal that among the naturally occurring N-terminal HTT peptides, the exon 1 peptide is exceptionally pathogenic and exhibits unique structural and biophysical behaviors that do not appear to be incremental changes compared with other fragments. If this proves correct, efforts to specifically reduce the levels of exon 1 peptides or to target toxicity-influencing post-translational modifications that occur with the exon 1 context are likely to have the greatest impact on pathology.
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Affiliation(s)
- Brett A Barbaro
- Department of Developmental and Cell Biology, University of California, Irvine 92697, USA
| | - Tamas Lukacsovich
- Department of Developmental and Cell Biology, University of California, Irvine 92697, USA
| | - Namita Agrawal
- Department of Developmental and Cell Biology, University of California, Irvine 92697, USA, Department of Zoology, University of Delhi, Delhi 110007, India
| | - John Burke
- Department of Developmental and Cell Biology, University of California, Irvine 92697, USA
| | - Doug J Bornemann
- Department of Developmental and Cell Biology, University of California, Irvine 92697, USA
| | - Judith M Purcell
- Department of Developmental and Cell Biology, University of California, Irvine 92697, USA
| | - Shane A Worthge
- Department of Developmental and Cell Biology, University of California, Irvine 92697, USA
| | | | | | - Wan Song
- Department of Developmental and Cell Biology, University of California, Irvine 92697, USA
| | - Olga A Morozova
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA
| | - David W Colby
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA
| | - J Lawrence Marsh
- Department of Developmental and Cell Biology, University of California, Irvine 92697, USA,
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84
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Baksi S, Basu S, Mukhopadhyay D. Mutant huntingtin replaces Gab1 and interacts with C-terminal SH3 domain of growth factor receptor binding protein 2 (Grb2). Neurosci Res 2014; 87:77-83. [DOI: 10.1016/j.neures.2014.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 06/18/2014] [Accepted: 06/25/2014] [Indexed: 10/25/2022]
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85
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Francelle L, Galvan L, Brouillet E. Possible involvement of self-defense mechanisms in the preferential vulnerability of the striatum in Huntington's disease. Front Cell Neurosci 2014; 8:295. [PMID: 25309327 PMCID: PMC4176035 DOI: 10.3389/fncel.2014.00295] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 09/03/2014] [Indexed: 01/01/2023] Open
Abstract
HD is caused by a mutation in the huntingtin gene that consists in a CAG repeat expansion translated into an abnormal poly-glutamine (polyQ) tract in the huntingtin (Htt) protein. The most striking neuropathological finding in HD is the atrophy of the striatum. The regional expression of mutant Htt (mHtt) is ubiquitous in the brain and cannot explain by itself the preferential vulnerability of the striatum in HD. mHtt has been shown to produce an early defect in transcription, through direct alteration of the function of key regulators of transcription and in addition, more indirectly, as a result of compensatory responses to cellular stress. In this review, we focus on gene products that are preferentially expressed in the striatum and have down- or up-regulated expression in HD and, as such, may play a crucial role in the susceptibility of the striatum to mHtt. Many of these striatal gene products are for a vast majority down-regulated and more rarely increased in HD. Recent research shows that some of these striatal markers have a pro-survival/neuroprotective role in neurons (e.g., MSK1, A2A, and CB1 receptors) whereas others enhance the susceptibility of striatal neurons to mHtt (e.g., Rhes, RGS2, D2 receptors). The down-regulation of these latter proteins may be considered as a potential self-defense mechanism to slow degeneration. For a majority of the striatal gene products that have been identified so far, their function in the striatum is unknown and their modifying effects on mHtt toxicity remain to be experimentally addressed. Focusing on these striatal markers may contribute to a better understanding of HD pathogenesis, and possibly the identification of novel therapeutic targets.
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Affiliation(s)
- Laetitia Francelle
- Neurodegenerative Disease Laboratory, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Direction des Sciences du Vivant, Institut d'Imagerie BioMédicale, Molecular Imaging Research Center Fontenay-aux-Roses, France ; Centre National de la Recherche Scientifique - Commissariat à l'Énergie Atomique et aux Énergies Alternatives Unité de Recherche Associée 2210 Fontenay-aux-Roses, France
| | - Laurie Galvan
- Neurodegenerative Disease Laboratory, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Direction des Sciences du Vivant, Institut d'Imagerie BioMédicale, Molecular Imaging Research Center Fontenay-aux-Roses, France ; Centre National de la Recherche Scientifique - Commissariat à l'Énergie Atomique et aux Énergies Alternatives Unité de Recherche Associée 2210 Fontenay-aux-Roses, France ; Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, Brain Research Institute, David Geffen School of Medicine, University of California Los Angeles Los Angeles, CA, USA
| | - Emmanuel Brouillet
- Neurodegenerative Disease Laboratory, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Direction des Sciences du Vivant, Institut d'Imagerie BioMédicale, Molecular Imaging Research Center Fontenay-aux-Roses, France ; Centre National de la Recherche Scientifique - Commissariat à l'Énergie Atomique et aux Énergies Alternatives Unité de Recherche Associée 2210 Fontenay-aux-Roses, France
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Ribeiro FM, Hamilton A, Doria JG, Guimaraes IM, Cregan SP, Ferguson SS. Metabotropic glutamate receptor 5 as a potential therapeutic target in Huntington's disease. Expert Opin Ther Targets 2014; 18:1293-304. [PMID: 25118797 DOI: 10.1517/14728222.2014.948419] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by a polyglutamine expansion in the amino-terminal region of the huntingtin (htt) protein, which underlies the loss of striatal and cortical neurons. Glutamate has been implicated in a number of neurodegenerative diseases, and several studies suggest that the metabotropic glutamate receptor 5 (mGluR5) may represent a target for the treatment of HD. AREAS COVERED The main goal of this review is to discuss the current data in the literature regarding the role of mGluR5 in HD and evaluate the potential of mGluR5 as a therapeutic target for the treatment of HD. mGluR5 is highly expressed in the brain regions affected in HD and is involved in movement control. Moreover, mGluR5 interacts with htt and mutated htt profoundly affects mGluR5 signaling. However, mGluR5 stimulation can activate both neuroprotective and neurotoxic signaling pathways, depending on the context of activation. EXPERT OPINION Although the data published so far strongly indicate that mGluR5 plays a major role in HD-associated neurodegeneration, htt aggregation and motor symptoms, it is not clear whether mGluR5 stimulation can diminish or intensify neuronal cell loss and HD progression. Thus, future experiments will be necessary to further investigate the outcome of drugs acting on mGluR5 for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Fabiola M Ribeiro
- Universidade Federal de Minas Gerais, Departamento de Bioquimica e Imunologia, ICB , Belo Horizonte 31270-901 , Brazil
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87
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The neuronal activity-driven transcriptome. Mol Neurobiol 2014; 51:1071-88. [PMID: 24935719 DOI: 10.1007/s12035-014-8772-z] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 06/01/2014] [Indexed: 10/25/2022]
Abstract
Activity-driven transcription is a key event associated with long-lasting forms of neuronal plasticity. Despite the efforts to investigate the regulatory mechanisms that control this complex process and the important advances in the knowledge of the function of many activity-induced genes in neurons, as well as the specific contribution of activity-regulated transcription factors, our understanding of how activity-driven transcription operates at the systems biology level is still very limited. This review focuses on the research of neuronal activity-driven transcription from an "omics" perspective. We will discuss the different high-throughput approaches undertaken to characterize the gene programs downstream of specific activity-regulated transcription factors, including CREB, SRF, MeCP2, Fos, Npas4, and others, and the interplay between epigenetic and transcriptional mechanisms underlying neuronal plasticity changes. Although basic questions remain unanswered and important challenges still lie ahead, the refinement of genome-wide techniques for investigating the neuronal transcriptome and epigenome promises great advances.
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88
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Valor LM. Transcription, epigenetics and ameliorative strategies in Huntington's Disease: a genome-wide perspective. Mol Neurobiol 2014; 51:406-23. [PMID: 24788684 PMCID: PMC4309905 DOI: 10.1007/s12035-014-8715-8] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 04/11/2014] [Indexed: 12/18/2022]
Abstract
Transcriptional dysregulation in Huntington’s disease (HD) is an early event that shapes the brain transcriptome by both the depletion and ectopic activation of gene products that eventually affect survival and neuronal functions. Disruption in the activity of gene expression regulators, such as transcription factors, chromatin-remodeling proteins, and noncoding RNAs, accounts for the expression changes observed in multiple animal and cellular models of HD and in samples from patients. Here, I review the recent advances in the study of HD transcriptional dysregulation and its causes to finally discuss the possible implications in ameliorative strategies from a genome-wide perspective. To date, the use of genome-wide approaches, predominantly based on microarray platforms, has been successful in providing an extensive catalog of differentially regulated genes, including biomarkers aimed at monitoring the progress of the pathology. Although still incipient, the introduction of combined next-generation sequencing techniques is enhancing our comprehension of the mechanisms underlying altered transcriptional dysregulation in HD by providing the first genomic landscapes associated with epigenetics and the occupancy of transcription factors. In addition, the use of genome-wide approaches is becoming more and more necessary to evaluate the efficacy and safety of ameliorative strategies and to identify novel mechanisms of amelioration that may help in the improvement of current preclinical therapeutics. Finally, the major conclusions obtained from HD transcriptomics studies have the potential to be extrapolated to other neurodegenerative disorders.
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Affiliation(s)
- Luis M Valor
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, Av. Santiago Ramón y Cajal s/n, Sant Joan d'Alacant, 03550, Alicante, Spain,
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Ross CA, Aylward EH, Wild EJ, Langbehn DR, Long JD, Warner JH, Scahill RI, Leavitt BR, Stout JC, Paulsen JS, Reilmann R, Unschuld PG, Wexler A, Margolis RL, Tabrizi SJ. Huntington disease: natural history, biomarkers and prospects for therapeutics. Nat Rev Neurol 2014; 10:204-16. [PMID: 24614516 DOI: 10.1038/nrneurol.2014.24] [Citation(s) in RCA: 668] [Impact Index Per Article: 66.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Huntington disease (HD) can be seen as a model neurodegenerative disorder, in that it is caused by a single genetic mutation and is amenable to predictive genetic testing, with estimation of years to predicted onset, enabling the entire range of disease natural history to be studied. Structural neuroimaging biomarkers show that progressive regional brain atrophy begins many years before the emergence of diagnosable signs and symptoms of HD, and continues steadily during the symptomatic or 'manifest' period. The continued development of functional, neurochemical and other biomarkers raises hopes that these biomarkers might be useful for future trials of disease-modifying therapeutics to delay the onset and slow the progression of HD. Such advances could herald a new era of personalized preventive therapeutics. We describe the natural history of HD, including the timing of emergence of motor, cognitive and emotional impairments, and the techniques that are used to assess these features. Building on this information, we review recent progress in the development of biomarkers for HD, and potential future roles of these biomarkers in clinical trials.
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Affiliation(s)
- Christopher A Ross
- Division of Neurobiology, Johns Hopkins University, 600 North Wolfe Street, Baltimore, MD 21287, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | - Russell L Margolis
- Division of Neurobiology, Johns Hopkins University, 600 North Wolfe Street, Baltimore, MD 21287, USA
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90
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Tourette C, Li B, Bell R, O'Hare S, Kaltenbach LS, Mooney SD, Hughes RE. A large scale Huntingtin protein interaction network implicates Rho GTPase signaling pathways in Huntington disease. J Biol Chem 2014; 289:6709-6726. [PMID: 24407293 DOI: 10.1074/jbc.m113.523696] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Huntington disease (HD) is an inherited neurodegenerative disease caused by a CAG expansion in the HTT gene. Using yeast two-hybrid methods, we identified a large set of proteins that interact with huntingtin (HTT)-interacting proteins. This network, composed of HTT-interacting proteins (HIPs) and proteins interacting with these primary nodes, contains 3235 interactions among 2141 highly interconnected proteins. Analysis of functional annotations of these proteins indicates that primary and secondary HIPs are enriched in pathways implicated in HD, including mammalian target of rapamycin, Rho GTPase signaling, and oxidative stress response. To validate roles for HIPs in mutant HTT toxicity, we show that the Rho GTPase signaling components, BAIAP2, EZR, PIK3R1, PAK2, and RAC1, are modifiers of mutant HTT toxicity. We also demonstrate that Htt co-localizes with BAIAP2 in filopodia and that mutant HTT interferes with filopodial dynamics. These data indicate that HTT is involved directly in membrane dynamics, cell attachment, and motility. Furthermore, they implicate dysregulation in these pathways as pathological mechanisms in HD.
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Affiliation(s)
| | - Biao Li
- Buck Institute for Research on Aging, Novato, California 94945
| | - Russell Bell
- Prolexys Pharmaceuticals, Salt Lake City, Utah 84116; Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112
| | - Shannon O'Hare
- Buck Institute for Research on Aging, Novato, California 94945
| | - Linda S Kaltenbach
- Prolexys Pharmaceuticals, Salt Lake City, Utah 84116; Center for Drug Discovery and Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27704
| | - Sean D Mooney
- Buck Institute for Research on Aging, Novato, California 94945.
| | - Robert E Hughes
- Buck Institute for Research on Aging, Novato, California 94945.
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91
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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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92
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Valor LM, Guiretti D. What's wrong with epigenetics in Huntington's disease? Neuropharmacology 2013; 80:103-14. [PMID: 24184315 DOI: 10.1016/j.neuropharm.2013.10.025] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 10/16/2013] [Accepted: 10/21/2013] [Indexed: 12/15/2022]
Abstract
Huntington's disease (HD) can be considered the paradigm of epigenetic dysregulation in neurodegenerative disorders. In this review, we attempted to compile the evidence that indicates, on the one hand, that several epigenetic marks (histone acetylation, methylation, ubiquitylation, phosphorylation and DNA modifications) are altered in multiple models and in postmortem patient samples, and on the other hand, that pharmacological treatments aimed to reverse such alterations have beneficial effects on HD phenotypic and biochemical traits. However, the working hypotheses regarding the biological significance of epigenetic dysregulation in this disease and the mechanisms of action of the tested ameliorative strategies need to be refined. Understanding the complexity of the epigenetics in HD will provide useful insights to examine the role of epigenetic dysregulation in other neuropathologies, such as Alzheimer's or Parkinson's diseases.
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Affiliation(s)
- Luis M Valor
- Instituto de Neurociencias de Alicante (Universidad Miguel Hernández, Consejo Superior de Investigaciones Científicas), Av. Santiago Ramón y Cajal s/n, Sant Joan d'Alacant, 03550 Alicante, Spain.
| | - Deisy Guiretti
- Instituto de Neurociencias de Alicante (Universidad Miguel Hernández, Consejo Superior de Investigaciones Científicas), Av. Santiago Ramón y Cajal s/n, Sant Joan d'Alacant, 03550 Alicante, Spain
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93
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Diamanti D, Mori E, Incarnato D, Malusa F, Fondelli C, Magnoni L, Pollio G. Whole gene expression profile in blood reveals multiple pathways deregulation in R6/2 mouse model. Biomark Res 2013; 1:28. [PMID: 24252798 PMCID: PMC4177605 DOI: 10.1186/2050-7771-1-28] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 10/15/2013] [Indexed: 01/04/2023] Open
Abstract
Background Huntington Disease (HD) is a progressive neurological disorder, with pathological manifestations in brain areas and in periphery caused by the ubiquitous expression of mutant Huntingtin protein. Transcriptional dysregulation is considered a key molecular mechanism responsible of HD pathogenesis but, although numerous studies investigated mRNA alterations in HD, so far none evaluated a whole gene expression profile in blood of R6/2 mouse model. Findings To discover novel pathogenic mechanisms and potential peripheral biomarkers useful to monitor disease progression or drug efficacy, a microarray study was performed in blood of R6/2 at manifest stage and wild type littermate mice. This approach allowed to propose new peripheral molecular processes involved in HD and to suggest different panels of candidate biomarkers. Among the discovered deregulated processes, we focused on specific ones: complement and coagulation cascades, PPAR signaling, cardiac muscle contraction, and dilated cardiomyopathy pathways. Selected genes derived from these pathways were additionally investigated in other accessible tissues to validate these matrices as source of biomarkers, and in brain, to link central and peripheral disease manifestations. Conclusions Our findings validated the skeletal muscle as suitable source to investigate peripheral transcriptional alterations in HD and supported the hypothesis that immunological alteration may contribute to neurological degeneration. Moreover, the identification of altered signaling in mouse blood enforce R6/2 transgenic mouse as a powerful HD model while suggesting novel disease biomarkers for pre-clinical investigation.
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Affiliation(s)
- Daniela Diamanti
- Siena Biotech S,p,A,, strada del Petriccio e Belriguardo, Siena 35, 53100, Italy.
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Goodall EF, Heath PR, Bandmann O, Kirby J, Shaw PJ. Neuronal dark matter: the emerging role of microRNAs in neurodegeneration. Front Cell Neurosci 2013; 7:178. [PMID: 24133413 PMCID: PMC3794211 DOI: 10.3389/fncel.2013.00178] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Accepted: 09/21/2013] [Indexed: 12/17/2022] Open
Abstract
MicroRNAs (miRNAs) are small, abundant RNA molecules that constitute part of the cell's non-coding RNA “dark matter.” In recent years, the discovery of miRNAs has revolutionised the traditional view of gene expression and our understanding of miRNA biogenesis and function has expanded. Altered expression of miRNAs is increasingly recognized as a feature of many disease states, including neurodegeneration. Here, we review the emerging role for miRNA dysfunction in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS) and Huntington's disease pathogenesis. We emphasize the complex nature of gene regulatory networks and the need for systematic studies, with larger sample cohorts than have so far been reported, to reveal the most important miRNA regulators in disease. Finally, miRNA diversity and their potential to target multiple pathways, offers novel clinical applications for miRNAs as biomarkers and therapeutic agents in neurodegenerative diseases.
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Affiliation(s)
- Emily F Goodall
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience, University of Sheffield Sheffield, UK
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95
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Sbodio JI, Paul BD, Machamer CE, Snyder SH. Golgi protein ACBD3 mediates neurotoxicity associated with Huntington's disease. Cell Rep 2013; 4:890-7. [PMID: 24012756 PMCID: PMC3801179 DOI: 10.1016/j.celrep.2013.08.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/02/2013] [Accepted: 08/01/2013] [Indexed: 01/10/2023] Open
Abstract
Huntington's disease (HD) is an autosomal-dominant neurodegenerative disease caused by the expansion of polyglutamine repeats in the gene for huntingtin (Htt). In HD, the corpus striatum selectively degenerates despite the uniform expression of mutant huntingtin (mHtt) throughout the brain and body. Striatal selectivity reflects the binding of the striatal-selective protein Rhes to mHtt to augment cytotoxicity, but molecular mechanisms underlying the toxicity have been elusive. Here, we report that the Golgi protein acyl-CoA binding domain containing 3 (ACBD3) mediates mHtt cytotoxicity via a Rhes/mHtt/ACBD3 complex. ACBD3 levels are markedly elevated in the striatum of HD patients, in a striatal cell line harboring polyglutamine repeats, and in the brains of HD mice. Moreover, ACBD3 deletion abolishes HD neurotoxicity, which is increased by ACBD3 overexpression. Enhanced levels of ACBD3 elicited by endoplasmic reticulum, mitochondrial, and Golgi stresses may account for HD-associated augmentation of ACBD3 and neurodegeneration.
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Affiliation(s)
- Juan I. Sbodio
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD. 21205, USA
| | - Bindu D. Paul
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD. 21205, USA
| | - Carolyn E. Machamer
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD. 21205, USA
| | - Solomon H. Snyder
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD. 21205, USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University, Baltimore, MD. 21205, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, Baltimore, MD. 21205, USA
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96
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Abstract
Transcriptional dysregulation is an early feature of Huntington disease (HD). We observed gene-specific changes in histone H3 lysine 4 trimethylation (H3K4me3) at transcriptionally repressed promoters in R6/2 mouse and human HD brain. Genome-wide analysis showed a chromatin signature for this mark. Reducing the levels of the H3K4 demethylase SMCX/Jarid1c in primary neurons reversed down-regulation of key neuronal genes caused by mutant Huntingtin expression. Finally, reduction of SMCX/Jarid1c in primary neurons from BACHD mice or the single Jarid1 in a Drosophila HD model was protective. Therefore, targeting this epigenetic signature may be an effective strategy to ameliorate the consequences of HD.
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97
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Valor LM, Guiretti D, Lopez-Atalaya JP, Barco A. Genomic landscape of transcriptional and epigenetic dysregulation in early onset polyglutamine disease. J Neurosci 2013; 33:10471-82. [PMID: 23785159 PMCID: PMC6618595 DOI: 10.1523/jneurosci.0670-13.2013] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 05/08/2013] [Accepted: 05/20/2013] [Indexed: 01/09/2023] Open
Abstract
Transcriptional dysregulation is an important early feature of polyglutamine diseases. One of its proposed causes is defective neuronal histone acetylation, but important aspects of this hypothesis, such as the precise genomic topography of acetylation deficits and the relationship between transcriptional and acetylation alterations at the whole-genome level, remain unknown. The new techniques for the mapping of histone post-translational modifications at genomic scale enable such global analyses and are challenging some assumptions about the role of specific histone modifications in gene expression. We examined here the genome-wide correlation of histone acetylation and gene expression defects in a mouse model of early onset Huntington's disease. Our analyses identified hundreds of loci that were hypoacetylated for H3K9,14 and H4K12 in the chromatin of these mice. Surprisingly, few genes with altered transcript levels in mutant mice showed significant changes in these acetylation marks and vice versa. Our screen, however, identified a subset of genes in which H3K9,14 deacetylation and transcriptional dysregulation concur. Genes in this group were consistently affected in different brain areas, mouse models, and tissue from patients, which suggests a role in the etiology of this pathology. Overall, the combination of histone acetylation and gene expression screenings demonstrates that histone deacetylation and transcriptional dysregulation are two early, largely independent, manifestations of polyglutamine disease and suggests that additional epigenetic marks or mechanisms are required for explaining the full range of transcriptional alterations associated with this disorder.
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Affiliation(s)
- Luis M. Valor
- Instituto de Neurociencias de Alicante (Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas), Sant Joan d'Alacant, 03550, Alicante, Spain
| | - Deisy Guiretti
- Instituto de Neurociencias de Alicante (Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas), Sant Joan d'Alacant, 03550, Alicante, Spain
| | - Jose P. Lopez-Atalaya
- Instituto de Neurociencias de Alicante (Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas), Sant Joan d'Alacant, 03550, Alicante, Spain
| | - Angel Barco
- Instituto de Neurociencias de Alicante (Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas), Sant Joan d'Alacant, 03550, Alicante, Spain
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98
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Huntington's disease: underlying molecular mechanisms and emerging concepts. Trends Biochem Sci 2013; 38:378-85. [PMID: 23768628 DOI: 10.1016/j.tibs.2013.05.003] [Citation(s) in RCA: 240] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 05/06/2013] [Accepted: 05/17/2013] [Indexed: 11/22/2022]
Abstract
Huntington's disease (HD) is a progressive neurodegenerative disorder for which no disease modifying treatments exist. Many molecular changes and cellular consequences that underlie HD are observed in other neurological disorders, suggesting that common pathological mechanisms and pathways may exist. Recent findings have enhanced our understanding of the way cells regulate and respond to expanded polyglutamine proteins such as mutant huntingtin. These studies demonstrate that in addition to effects on folding, aggregation, and clearance pathways, a general transcriptional mechanism also dictates the expression of polyglutamine proteins. Here, we summarize the key pathways and networks that are important in HD in the context of recent therapeutic advances and highlight how their interplay may be of relevance to other protein folding disorders.
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99
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Basu M, Bhattacharyya NP, Mohanty PK. Comparison of modules of wild type and mutant Huntingtin and TP53 protein interaction networks: implications in biological processes and functions. PLoS One 2013; 8:e64838. [PMID: 23741403 PMCID: PMC3669416 DOI: 10.1371/journal.pone.0064838] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Accepted: 04/19/2013] [Indexed: 02/07/2023] Open
Abstract
Disease-causing mutations usually change the interacting partners of mutant proteins. In this article, we propose that the biological consequences of mutation are directly related to the alteration of corresponding protein protein interaction networks (PPIN). Mutation of Huntingtin (HTT) which causes Huntington's disease (HD) and mutations to TP53 which is associated with different cancers are studied as two example cases. We construct the PPIN of wild type and mutant proteins separately and identify the structural modules of each of the networks. The functional role of these modules are then assessed by Gene Ontology (GO) enrichment analysis for biological processes (BPs). We find that a large number of significantly enriched () GO terms in mutant PPIN were absent in the wild type PPIN indicating the gain of BPs due to mutation. Similarly some of the GO terms enriched in wild type PPIN cease to exist in the modules of mutant PPIN, representing the loss. GO terms common in modules of mutant and wild type networks indicate both loss and gain of BPs. We further assign relevant biological function(s) to each module by classifying the enriched GO terms associated with it. It turns out that most of these biological functions in HTT networks are already known to be altered in HD and those of TP53 networks are altered in cancers. We argue that gain of BPs, and the corresponding biological functions, are due to new interacting partners acquired by mutant proteins. The methodology we adopt here could be applied to genetic diseases where mutations alter the ability of the protein to interact with other proteins.
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Affiliation(s)
- Mahashweta Basu
- Theoretical Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Bidhan Nagar, Kolkata, India
| | - Nitai P. Bhattacharyya
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Bidhan Nagar, Kolkata, India
| | - Pradeep K. Mohanty
- Theoretical Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Bidhan Nagar, Kolkata, India
- * E-mail:
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100
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Wang F, Yang Y, Lin X, Wang JQ, Wu YS, Xie W, Wang D, Zhu S, Liao YQ, Sun Q, Yang YG, Luo HR, Guo C, Han C, Tang TS. Genome-wide loss of 5-hmC is a novel epigenetic feature of Huntington's disease. Hum Mol Genet 2013; 22:3641-53. [PMID: 23669348 DOI: 10.1093/hmg/ddt214] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
5-Hydroxymethylcytosine (5-hmC) may represent a new epigenetic modification of cytosine. While the dynamics of 5-hmC during neurodevelopment have recently been reported, little is known about its genomic distribution and function(s) in neurodegenerative diseases such as Huntington's disease (HD). We here observed a marked reduction of the 5-hmC signal in YAC128 (yeast artificial chromosome transgene with 128 CAG repeats) HD mouse brain tissues when compared with age-matched wild-type (WT) mice, suggesting a deficiency of 5-hmC reconstruction in HD brains during postnatal development. Genome-wide distribution analysis of 5-hmC further confirmed the diminishment of the 5-hmC signal in striatum and cortex in YAC128 HD mice. General genomic features of 5-hmC are highly conserved, not being affected by either disease or brain regions. Intriguingly, we have identified disease-specific (YAC128 versus WT) differentially hydroxymethylated regions (DhMRs), and found that acquisition of DhmRs in gene body is a positive epigenetic regulator for gene expression. Ingenuity pathway analysis (IPA) of genotype-specific DhMR-annotated genes revealed that alternation of a number of canonical pathways involving neuronal development/differentiation (Wnt/β-catenin/Sox pathway, axonal guidance signaling pathway) and neuronal function/survival (glutamate receptor/calcium/CREB, GABA receptor signaling, dopamine-DARPP32 feedback pathway, etc.) could be important for the onset of HD. Our results indicate that loss of the 5-hmC marker is a novel epigenetic feature in HD, and that this aberrant epigenetic regulation may impair the neurogenesis, neuronal function and survival in HD brain. Our study also opens a new avenue for HD treatment; re-establishing the native 5-hmC landscape may have the potential to slow/halt the progression of HD.
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Affiliation(s)
- Fengli Wang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, China
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