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Tejwani L, Ravindra NG, Lee C, Cheng Y, Nguyen B, Luttik K, Ni L, Zhang S, Morrison LM, Gionco J, Xiang Y, Yoon J, Ro H, Haidery F, Grijalva RM, Bae E, Kim K, Martuscello RT, Orr HT, Zoghbi HY, McLoughlin HS, Ranum LPW, Shakkottai VG, Faust PL, Wang S, van Dijk D, Lim J. Longitudinal single-cell transcriptional dynamics throughout neurodegeneration in SCA1. Neuron 2024; 112:362-383.e15. [PMID: 38016472 PMCID: PMC10922326 DOI: 10.1016/j.neuron.2023.10.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 09/10/2023] [Accepted: 10/27/2023] [Indexed: 11/30/2023]
Abstract
Neurodegeneration is a protracted process involving progressive changes in myriad cell types that ultimately results in the death of vulnerable neuronal populations. To dissect how individual cell types within a heterogeneous tissue contribute to the pathogenesis and progression of a neurodegenerative disorder, we performed longitudinal single-nucleus RNA sequencing of mouse and human spinocerebellar ataxia type 1 (SCA1) cerebellar tissue, establishing continuous dynamic trajectories of each cell population. Importantly, we defined the precise transcriptional changes that precede loss of Purkinje cells and, for the first time, identified robust early transcriptional dysregulation in unipolar brush cells and oligodendroglia. Finally, we applied a deep learning method to predict disease state accurately and identified specific features that enable accurate distinction of wild-type and SCA1 cells. Together, this work reveals new roles for diverse cerebellar cell types in SCA1 and provides a generalizable analysis framework for studying neurodegeneration.
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Affiliation(s)
- Leon Tejwani
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA.
| | - Neal G Ravindra
- Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06510, USA; Department of Computer Science, Yale University, New Haven, CT 06510, USA
| | - Changwoo Lee
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA
| | - Yubao Cheng
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Billy Nguyen
- University of California, San Francisco School of Medicine, San Francisco, CA 94143, USA
| | - Kimberly Luttik
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA
| | - Luhan Ni
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Shupei Zhang
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Logan M Morrison
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - John Gionco
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center and the New York Presbyterian Hospital, New York, NY 10032, USA
| | - Yangfei Xiang
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA; Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06510, USA
| | | | - Hannah Ro
- Yale College, New Haven, CT 06510, USA
| | | | - Rosalie M Grijalva
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA
| | | | - Kristen Kim
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Psychiatry, Yale School of Medicine, New Haven, CT 06510, USA
| | - Regina T Martuscello
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center and the New York Presbyterian Hospital, New York, NY 10032, USA
| | - Harry T Orr
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Huda Y Zoghbi
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA; Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hayley S McLoughlin
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Laura P W Ranum
- Department of Molecular Genetics and Microbiology, Center for Neurogenetics, College of Medicine, Genetics Institute, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Vikram G Shakkottai
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Phyllis L Faust
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center and the New York Presbyterian Hospital, New York, NY 10032, USA
| | - Siyuan Wang
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA; Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA.
| | - David van Dijk
- Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06510, USA; Department of Computer Science, Yale University, New Haven, CT 06510, USA.
| | - Janghoo Lim
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510, USA; Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA; Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA; Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06510, USA; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale School of Medicine, New Haven, CT 06510, USA; Wu Tsai Institute, Yale School of Medicine, New Haven, CT 06510, USA.
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Voicu V, Tataru CP, Toader C, Covache-Busuioc RA, Glavan LA, Bratu BG, Costin HP, Corlatescu AD, Ciurea AV. Decoding Neurodegeneration: A Comprehensive Review of Molecular Mechanisms, Genetic Influences, and Therapeutic Innovations. Int J Mol Sci 2023; 24:13006. [PMID: 37629187 PMCID: PMC10455143 DOI: 10.3390/ijms241613006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 08/17/2023] [Accepted: 08/18/2023] [Indexed: 08/27/2023] Open
Abstract
Neurodegenerative disorders often acquire due to genetic predispositions and genomic alterations after exposure to multiple risk factors. The most commonly found pathologies are variations of dementia, such as frontotemporal dementia and Lewy body dementia, as well as rare subtypes of cerebral and cerebellar atrophy-based syndromes. In an emerging era of biomedical advances, molecular-cellular studies offer an essential avenue for a thorough recognition of the underlying mechanisms and their possible implications in the patient's symptomatology. This comprehensive review is focused on deciphering molecular mechanisms and the implications regarding those pathologies' clinical advancement and provides an analytical overview of genetic mutations in the case of neurodegenerative disorders. With the help of well-developed modern genetic investigations, these clinically complex disturbances are highly understood nowadays, being an important step in establishing molecularly targeted therapies and implementing those approaches in the physician's practice.
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Affiliation(s)
- Victor Voicu
- Pharmacology, Toxicology and Clinical Psychopharmacology, “Carol Davila” University of Medicine and Pharmacy in Bucharest, 020021 Bucharest, Romania;
- Medical Section within the Romanian Academy, 010071 Bucharest, Romania
| | - Calin Petre Tataru
- Department of Opthamology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania
- Central Military Emergency Hospital “Dr. Carol Davila”, 010825 Bucharest, Romania
| | - Corneliu Toader
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (R.-A.C.-B.); (L.A.G.); (B.-G.B.); (H.P.C.); (A.D.C.); (A.V.C.)
- Department of Vascular Neurosurgery, National Institute of Neurology and Neurovascular Diseases, 077160 Bucharest, Romania
| | - Razvan-Adrian Covache-Busuioc
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (R.-A.C.-B.); (L.A.G.); (B.-G.B.); (H.P.C.); (A.D.C.); (A.V.C.)
| | - Luca Andrei Glavan
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (R.-A.C.-B.); (L.A.G.); (B.-G.B.); (H.P.C.); (A.D.C.); (A.V.C.)
| | - Bogdan-Gabriel Bratu
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (R.-A.C.-B.); (L.A.G.); (B.-G.B.); (H.P.C.); (A.D.C.); (A.V.C.)
| | - Horia Petre Costin
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (R.-A.C.-B.); (L.A.G.); (B.-G.B.); (H.P.C.); (A.D.C.); (A.V.C.)
| | - Antonio Daniel Corlatescu
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (R.-A.C.-B.); (L.A.G.); (B.-G.B.); (H.P.C.); (A.D.C.); (A.V.C.)
| | - Alexandru Vlad Ciurea
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (R.-A.C.-B.); (L.A.G.); (B.-G.B.); (H.P.C.); (A.D.C.); (A.V.C.)
- Neurosurgery Department, Sanador Clinical Hospital, 010991 Bucharest, Romania
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Figueiredo AS, Loureiro JR, Macedo-Ribeiro S, Silveira I. Advances in Nucleotide Repeat Expansion Diseases: Transcription Gets in Phase. Cells 2023; 12:cells12060826. [PMID: 36980167 PMCID: PMC10047669 DOI: 10.3390/cells12060826] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/03/2023] [Accepted: 03/06/2023] [Indexed: 03/09/2023] Open
Abstract
Unstable DNA repeat expansions and insertions have been found to cause more than 50 neurodevelopmental, neurodegenerative, and neuromuscular disorders. One of the main hallmarks of repeat expansion diseases is the formation of abnormal RNA or protein aggregates in the neuronal cells of affected individuals. Recent evidence indicates that alterations of the dynamic or material properties of biomolecular condensates assembled by liquid/liquid phase separation are critical for the formation of these aggregates. This is a thermodynamically-driven and reversible local phenomenon that condenses macromolecules into liquid-like compartments responsible for compartmentalizing molecules required for vital cellular processes. Disease-associated repeat expansions modulate the phase separation properties of RNAs and proteins, interfering with the composition and/or the material properties of biomolecular condensates and resulting in the formation of abnormal aggregates. Since several repeat expansions have arisen in genes encoding crucial players in transcription, this raises the hypothesis that wide gene expression dysregulation is common to multiple repeat expansion diseases. This review will cover the impact of these mutations in the formation of aberrant aggregates and how they modify gene transcription.
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Affiliation(s)
- Ana S. Figueiredo
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, 4200-135 Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, 4050-313 Porto, Portugal
| | - Joana R. Loureiro
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, 4200-135 Porto, Portugal
| | - Sandra Macedo-Ribeiro
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, 4200-135 Porto, Portugal
| | - Isabel Silveira
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, 4200-135 Porto, Portugal
- Correspondence: ; Tel.: +351-2240-8800
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Luttik K, Tejwani L, Ju H, Driessen T, Smeets CJLM, Edamakanti CR, Khan A, Yun J, Opal P, Lim J. Differential effects of Wnt-β-catenin signaling in Purkinje cells and Bergmann glia in spinocerebellar ataxia type 1. Proc Natl Acad Sci U S A 2022; 119:e2208513119. [PMID: 35969780 PMCID: PMC9407543 DOI: 10.1073/pnas.2208513119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 06/25/2022] [Indexed: 12/11/2022] Open
Abstract
Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurodegenerative disease characterized by progressive ataxia and degeneration of specific neuronal populations, including Purkinje cells (PCs) in the cerebellum. Previous studies have demonstrated a critical role for various evolutionarily conserved signaling pathways in cerebellar patterning, such as the Wnt-β-catenin pathway; however, the roles of these pathways in adult cerebellar function and cerebellar neurodegeneration are largely unknown. In this study, we found that Wnt-β-catenin signaling activity was progressively enhanced in multiple cell types in the adult SCA1 mouse cerebellum, and that activation of this signaling occurs in an ataxin-1 polyglutamine (polyQ) expansion-dependent manner. Genetic manipulation of the Wnt-β-catenin signaling pathway in specific cerebellar cell populations revealed that activation of Wnt-β-catenin signaling in PCs alone was not sufficient to induce SCA1-like phenotypes, while its activation in astrocytes, including Bergmann glia (BG), resulted in gliosis and disrupted BG localization, which was replicated in SCA1 mouse models. Our studies identify a mechanism in which polyQ-expanded ataxin-1 positively regulates Wnt-β-catenin signaling and demonstrate that different cell types have distinct responses to the enhanced Wnt-β-catenin signaling in the SCA1 cerebellum, underscoring an important role of BG in SCA1 pathogenesis.
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Affiliation(s)
- Kimberly Luttik
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510
| | - Leon Tejwani
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510
| | - Hyoungseok Ju
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510
| | - Terri Driessen
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510
| | | | | | | | - Joy Yun
- Yale College, New Haven, CT 06510
| | - Puneet Opal
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Janghoo Lim
- Interdepartmental Neuroscience Program, Yale School of Medicine, New Haven, CT 06510
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT 06510
- Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06510
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5
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Abstract
Spinocerebellar ataxia type 1 (SCA1) is a fatal neurodegenerative disease caused by abnormal expansion of glutamine-encoding CAG repeats in the Ataxin-1 (ATXN1) gene. SCA1 is characterized by progressive motor deficits, cognitive decline, and mood changes including anxiety and depression, with longer number of repeats correlating with worse disease outcomes. While mouse models have been very useful in understanding etiology of ataxia and cognitive decline, our understanding of mood symptoms in SCA1 has lagged. It remains unclear whether anxiety or depression stem from an underlying brain pathology or as a consequence of living with an untreatable and lethal disease. To increase our understanding of the etiology of SCA1 mood alterations, we used the elevated-plus maze, sucrose preference and forced swim tests to assess mood in four different mouse lines. We found that SCA1 knock-in mice exhibit increased anxiety that correlated with the length of CAG repeats, supporting the idea that underlying brain pathology contributes to SCA1-like anxiety. Additionally, our results support the concept that increased anxiety is caused by non-cerebellar pathology, as Purkinje cell specific SCA1 transgenic mice exhibit decreased anxiety-like behavior. Regarding the molecular mechanism, partial loss of ATXN1 may play a role in anxiety, based on our results for Atxn1 haploinsufficient and null mice.
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Ataxin-1 regulates B cell function and the severity of autoimmune experimental encephalomyelitis. Proc Natl Acad Sci U S A 2020; 117:23742-23750. [PMID: 32878998 PMCID: PMC7519225 DOI: 10.1073/pnas.2003798117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ataxin-1 (ATXN1) is a ubiquitous polyglutamine protein expressed primarily in the nucleus where it binds chromatin and functions as a transcriptional repressor. Mutant forms of ataxin-1 containing expanded glutamine stretches cause the movement disorder spinocerebellar ataxia type 1 (SCA1) through a toxic gain-of-function mechanism in the cerebellum. Conversely, ATXN1 loss-of-function is implicated in cancer development and Alzheimer's disease (AD) pathogenesis. ATXN1 was recently nominated as a susceptibility locus for multiple sclerosis (MS). Here, we show that Atxn1-null mice develop a more severe experimental autoimmune encephalomyelitis (EAE) course compared to wildtype mice. The aggravated phenotype is mediated by increased T helper type 1 (Th1) cell polarization, which in turn results from the dysregulation of B cell activity. Ataxin-1 ablation in B cells leads to aberrant expression of key costimulatory molecules involved in proinflammatory T cell differentiation, including cluster of differentiation (CD)44 and CD80. In addition, comprehensive phosphoflow cytometry and transcriptional profiling link the exaggerated proliferation of ataxin-1 deficient B cells to the activation of extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription (STAT) pathways. Lastly, selective deletion of the physiological binding partner capicua (CIC) demonstrates the importance of ATXN1 native interactions for correct B cell functioning. Altogether, we report a immunomodulatory role for ataxin-1 and provide a functional description of the ATXN1 locus genetic association with MS risk.
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Niewiadomska-Cimicka A, Hache A, Trottier Y. Gene Deregulation and Underlying Mechanisms in Spinocerebellar Ataxias With Polyglutamine Expansion. Front Neurosci 2020; 14:571. [PMID: 32581696 PMCID: PMC7296114 DOI: 10.3389/fnins.2020.00571] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/11/2020] [Indexed: 12/14/2022] Open
Abstract
Polyglutamine spinocerebellar ataxias (polyQ SCAs) include SCA1, SCA2, SCA3, SCA6, SCA7, and SCA17 and constitute a group of adult onset neurodegenerative disorders caused by the expansion of a CAG repeat sequence located within the coding region of specific genes, which translates into polyglutamine tract in the corresponding proteins. PolyQ SCAs are characterized by degeneration of the cerebellum and its associated structures and lead to progressive ataxia and other diverse symptoms. In recent years, gene and epigenetic deregulations have been shown to play a critical role in the pathogenesis of polyQ SCAs. Here, we provide an overview of the functions of wild type and pathogenic polyQ SCA proteins in gene regulation, describe the extent and nature of gene expression changes and their pathological consequences in diseases, and discuss potential avenues to further investigate converging and distinct disease pathways and to develop therapeutic strategies.
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Affiliation(s)
- Anna Niewiadomska-Cimicka
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Strasbourg, France
| | - Antoine Hache
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Strasbourg, France
| | - Yvon Trottier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Strasbourg, France
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8
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Volovikov EA, Davidenko AV, Lagarkova MA. Molecular Mechanisms of Spinocerebellar Ataxia Type 1. RUSS J GENET+ 2020. [DOI: 10.1134/s102279542002012x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Rocha S, Vieira J, Vázquez N, López-Fernández H, Fdez-Riverola F, Reboiro-Jato M, Sousa AD, Vieira CP. ATXN1 N-terminal region explains the binding differences of wild-type and expanded forms. BMC Med Genomics 2019; 12:145. [PMID: 31655597 PMCID: PMC6814966 DOI: 10.1186/s12920-019-0594-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 09/24/2019] [Indexed: 12/21/2022] Open
Abstract
Background Wild-type (wt) polyglutamine (polyQ) regions are implicated in stabilization of protein-protein interactions (PPI). Pathological polyQ expansion, such as that in human Ataxin-1 (ATXN1), that causes spinocerebellar ataxia type 1 (SCA1), results in abnormal PPI. For ATXN1 a larger number of interactors has been reported for the expanded (82Q) than the wt (29Q) protein. Methods To understand how the expanded polyQ affects PPI, protein structures were predicted for wt and expanded ATXN1, as well as, for 71 ATXN1 interactors. Then, the binding surfaces of wt and expanded ATXN1 with the reported interactors were inferred. Results Our data supports that the polyQ expansion alters the ATXN1 conformation and that it enhances the strength of interaction with ATXN1 partners. For both ATXN1 variants, the number of residues at the predicted binding interface are greater after the polyQ, mainly due to the AXH domain. Moreover, the difference in the interaction strength of the ATXN1 variants was due to an increase in the number of interactions at the N-terminal region, before the polyQ, for the expanded form. Conclusions There are three regions at the AXH domain that are essential for ATXN1 PPI. The N-terminal region is responsible for the strength of the PPI with the ATXN1 variants. How the predicted motifs in this region affect PPI is discussed, in the context of ATXN1 post-transcriptional modifications.
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Affiliation(s)
- Sara Rocha
- Instituto de Biologia Molecular e Celular (IBMC), Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal
| | - Jorge Vieira
- Instituto de Biologia Molecular e Celular (IBMC), Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal
| | - Noé Vázquez
- ESEI - Escuela Superior de Ingeniería Informática, Edificio Politécnico, Campus Universitario As Lagoas s/n, Universidad de Vigo, 32004, Ourense, Spain.,Centro de Investigaciones Biomédicas (Centro Singular de Investigación de Galicia), Vigo, Spain.,SING Research Group, Galicia Sur Health Research Institute (IIS Galicia Sur). SERGAS-UVIGO, Vigo, Spain
| | - Hugo López-Fernández
- Instituto de Biologia Molecular e Celular (IBMC), Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.,ESEI - Escuela Superior de Ingeniería Informática, Edificio Politécnico, Campus Universitario As Lagoas s/n, Universidad de Vigo, 32004, Ourense, Spain.,Centro de Investigaciones Biomédicas (Centro Singular de Investigación de Galicia), Vigo, Spain.,SING Research Group, Galicia Sur Health Research Institute (IIS Galicia Sur). SERGAS-UVIGO, Vigo, Spain
| | - Florentino Fdez-Riverola
- ESEI - Escuela Superior de Ingeniería Informática, Edificio Politécnico, Campus Universitario As Lagoas s/n, Universidad de Vigo, 32004, Ourense, Spain.,Centro de Investigaciones Biomédicas (Centro Singular de Investigación de Galicia), Vigo, Spain.,SING Research Group, Galicia Sur Health Research Institute (IIS Galicia Sur). SERGAS-UVIGO, Vigo, Spain
| | - Miguel Reboiro-Jato
- ESEI - Escuela Superior de Ingeniería Informática, Edificio Politécnico, Campus Universitario As Lagoas s/n, Universidad de Vigo, 32004, Ourense, Spain.,Centro de Investigaciones Biomédicas (Centro Singular de Investigación de Galicia), Vigo, Spain.,SING Research Group, Galicia Sur Health Research Institute (IIS Galicia Sur). SERGAS-UVIGO, Vigo, Spain
| | - André D Sousa
- Instituto de Biologia Molecular e Celular (IBMC), Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal
| | - Cristina P Vieira
- Instituto de Biologia Molecular e Celular (IBMC), Rua Alfredo Allen, 208, 4200-135, Porto, Portugal. .,Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Rua Alfredo Allen, 208, 4200-135, Porto, Portugal.
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10
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Xiang C, Zhang S, Dong X, Ma S, Cong S. Transcriptional Dysregulation and Post-translational Modifications in Polyglutamine Diseases: From Pathogenesis to Potential Therapeutic Strategies. Front Mol Neurosci 2018; 11:153. [PMID: 29867345 PMCID: PMC5962650 DOI: 10.3389/fnmol.2018.00153] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 04/20/2018] [Indexed: 02/06/2023] Open
Abstract
Polyglutamine (polyQ) diseases are hereditary neurodegenerative disorders caused by an abnormal expansion of a trinucleotide CAG repeat in the coding region of their respective associated genes. PolyQ diseases mainly display progressive degeneration of the brain and spinal cord. Nine polyQ diseases are known, including Huntington's disease (HD), spinal and bulbar muscular atrophy (SBMA), dentatorubral-pallidoluysian atrophy (DRPLA), and six forms of spinocerebellar ataxia (SCA). HD is the best characterized polyQ disease. Many studies have reported that transcriptional dysregulation and post-translational disruptions, which may interact with each other, are central features of polyQ diseases. Post-translational modifications, such as the acetylation of histones, are closely associated with the regulation of the transcriptional activity. A number of groups have studied the interactions between the polyQ proteins and transcription factors. Pharmacological drugs or genetic manipulations aimed at correcting the dysregulation have been confirmed to be effective in the treatment of polyQ diseases in many animal and cellular models. For example, histone deaceylase inhibitors have been demonstrated to have beneficial effects in cases of HD, SBMA, DRPLA, and SCA3. In this review, we describe the transcriptional and post-translational dysregulation in polyQ diseases with special focus on HD, and we summarize and comment on potential treatment approaches targeting disruption of transcription and post-translation processes in these diseases.
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Affiliation(s)
| | | | | | | | - Shuyan Cong
- Department of Neurology, Shengjing Hospital of China Medical University, Shenyang, China
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11
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Kang AR, An HT, Ko J, Choi EJ, Kang S. Ataxin-1 is involved in tumorigenesis of cervical cancer cells via the EGFR-RAS-MAPK signaling pathway. Oncotarget 2017; 8:94606-94618. [PMID: 29212253 PMCID: PMC5706899 DOI: 10.18632/oncotarget.21814] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/20/2017] [Indexed: 12/24/2022] Open
Abstract
Ataxin-1 (ATXN1) is a coregulator protein within which expansion of the polyglutamine tract causes spinocerebellar ataxia type 1, an autosomal dominant neurodegenerative disorder. Previously, we reported that ATXN1 regulates the epithelial–mesenchymal transition of cervical cancer cells. In the present study, we demonstrate that ATXN1 is involved in cervical cancer tumorigenesis by promoting the proliferation of human cervical cancer cells. Chromatin immunoprecipitation assays showed that ATXN1 bound to the promoter region within cyclin D1 and activated cyclin D1 transcription, resulting in cell proliferation. ATXN1 promoted cyclin D1 expression through the EGFR–RAS–MAPK signaling pathway. Mouse xenograft tumorigenicity assays showed that ATXN1 downregulation inhibited tumorigenesis in cervical cancer cell lines in nude mice. Human cervical cancer tissue microarrays and immunohistochemical techniques showed that ATXN1 was significantly upregulated in many such tissues. Our results suggest that ATXN1 plays an important role in cervical cancer tumorigenesis and is a prognostic marker for cervical cancer.
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Affiliation(s)
- A-Ram Kang
- Division of Life Sciences, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Korea
| | - Hyoung-Tae An
- Division of Life Sciences, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Korea
| | - Jesang Ko
- Division of Life Sciences, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Korea
| | - Eui-Ju Choi
- Division of Life Sciences, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Korea
| | - Seongman Kang
- Division of Life Sciences, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Korea
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12
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Keiser MS, Monteys AM, Corbau R, Gonzalez-Alegre P, Davidson BL. RNAi prevents and reverses phenotypes induced by mutant human ataxin-1. Ann Neurol 2016; 80:754-765. [PMID: 27686464 PMCID: PMC5115960 DOI: 10.1002/ana.24789] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 09/18/2016] [Accepted: 09/25/2016] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Spinocerebellar ataxia type 1 is an autosomal dominant fatal neurodegenerative disease caused by a polyglutamine expansion in the coding region of ATXN1. We showed previously that partial suppression of mutant ataxin-1 (ATXN1) expression, using virally expressed RNAi triggers, could prevent disease symptoms in a transgenic mouse model and a knockin mouse model of the disease, using a single dose of virus. Here, we set out to test whether RNAi triggers targeting ATXN1 could not only prevent, but also reverse disease readouts when delivered after symptom onset. METHODS We administered recombinant adeno-associated virus (rAAV) expressing miS1, an artificial miRNA targeting human ATXN1 mRNA (rAAV.miS1), to a mouse model of spinocerebellar ataxia type 1 (SCA1; B05 mice). Viruses were delivered prior to or after symptom onset at multiple doses. Control B05 mice were treated with rAAVs expressing a control artificial miRNA, or with saline. Animal behavior, molecular phenotypes, neuropathology, and magnetic resonance spectroscopy were done on all groups, and data were compared to wild-type littermates. RESULTS We found that SCA1 phenotypes could be reversed by partial suppression of human mutant ATXN1 mRNA by rAAV.miS1 when delivered after symptom onset. We also identified the therapeutic range of rAAV.miS1 that could prevent or reverse disease readouts. INTERPRETATION SCA1 disease may be reversible by RNAi therapy, and the doses required for advancing this therapy to humans are delineated. Ann Neurol 2016;80:754-765.
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Affiliation(s)
- Megan S Keiser
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Alejandro Mas Monteys
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Romuald Corbau
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA.,Spark Therapeutics, Philadelphia, PA
| | - Pedro Gonzalez-Alegre
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Neurology, University of Pennsylvania, Philadelphia, PA
| | - Beverly L Davidson
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA
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Wagner JL, O'Connor DM, Donsante A, Boulis NM. Gene, Stem Cell, and Alternative Therapies for SCA 1. Front Mol Neurosci 2016; 9:67. [PMID: 27570504 PMCID: PMC4981596 DOI: 10.3389/fnmol.2016.00067] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 07/26/2016] [Indexed: 12/26/2022] Open
Abstract
Spinocerebellar ataxia 1 is an autosomal dominant disease characterized by neurodegeneration and motor dysfunction. In disease pathogenesis, polyglutamine expansion within Ataxin-1, a gene involved in transcriptional repression, causes protein nuclear inclusions to form. Most notably, neuronal dysfunction presents in Purkinje cells. However, the effect of mutant Ataxin-1 is not entirely understood. Two mouse models are employed to represent spinocerebellar ataxia 1, a B05 transgenic model that specifically expresses mutant Ataxin-1 in Purkinje cells, and a Sca1 154Q/2Q model that inserts the polyglutamine expansion into the mouse Ataxin-1 locus so that the mutant Ataxin-1 is expressed in all cells that express Ataxin-1. This review aims to summarize and evaluate the wide variety of therapies proposed for spinocerebellar ataxia 1, specifically gene and stem cell therapies.
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Affiliation(s)
- Jacob L Wagner
- Boulis Laboratory, Department of Neurosurgery, Emory School of Medicine Atlanta, GA, USA
| | - Deirdre M O'Connor
- Boulis Laboratory, Department of Neurosurgery, Emory School of Medicine Atlanta, GA, USA
| | - Anthony Donsante
- Boulis Laboratory, Department of Neurosurgery, Emory School of Medicine Atlanta, GA, USA
| | - Nicholas M Boulis
- Boulis Laboratory, Department of Neurosurgery, Emory School of Medicine Atlanta, GA, USA
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Sánchez I, Balagué E, Matilla-Dueñas A. Ataxin-1 regulates the cerebellar bioenergetics proteome through the GSK3β-mTOR pathway which is altered in Spinocerebellar ataxia type 1 (SCA1). Hum Mol Genet 2016; 25:4021-4040. [PMID: 27466200 DOI: 10.1093/hmg/ddw242] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 06/21/2016] [Accepted: 07/11/2016] [Indexed: 12/17/2022] Open
Abstract
A polyglutamine expansion within the ataxin-1 protein (ATXN1) underlies spinocerebellar ataxia type-1 (SCA1), a neurological disorder mainly characterized by ataxia and cerebellar deficits. In SCA1, both loss and gain of ATXN1 biological functions contribute to cerebellar pathogenesis. However, the critical ATXN1 functions and pathways involved remain unclear. To further investigate the early signalling pathways regulated by ATXN1, we performed an unbiased proteomic study of the Atxn1-KO 5-week-old mice cerebellum. Here, we show that lack of ATXN1 expression induces early alterations in proteins involved in glycolysis [pyruvate kinase, muscle, isoform 1 protein (PKM-i1), citrate synthase (CS), glycerol-3-phosphate dehydrogenase 2 (GPD2), glucose-6-phosphate isomerase (GPI), alpha -: enolase (ENO1)], ATP synthesis [CS, Succinate dehydrogenase complex,subunit A (SDHA), ATP synthase subunit d, mitochondrial (ATP5H)] and oxidative stress [peroxiredoxin-6 (PRDX6), aldehyde dehydrogenase family 1, subfamily A1, 10-formyltetrahydrofolate dehydrogenase]. In the SCA1 mice, several of these proteins (PKM-i1, ATP5H, PRDX6, proteome subunit A6) were down-regulated and ATP levels decreased. The underlying mechanism does not involve modulation of mitochondrial biogenesis, but dysregulation of the activity of the metabolic regulators glycogen synthase kinase 3B (GSK3β), decreased in Atxn1-KO and increased in SCA1 mice, and mechanistic target of rapamycin (serine/threonine kinase) (mTOR), unchanged in the Atxn1-KO and decreased in SCA1 mice cerebellum before the onset of ataxic symptoms. Pharmacological inhibition of GSK3β and activation of mTOR in a SCA1 cell model ameliorated identified ATXN1-regulated metabolic proteome and ATP alterations. Taken together, these results point to an early role of ATXN1 in the regulation of bioenergetics homeostasis in the mouse cerebellum. Moreover, data suggest GSK3β and mTOR pathways modulate this ATXN1 function in SCA1 pathogenesis that could be targeted therapeutically prior to the onset of disease symptoms in SCA1 and other pathologies involving dysregulation of ATXN1 functions.
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Affiliation(s)
- Ivelisse Sánchez
- Functional and Translational Neurogenetics Unit, Department of Neurosciences, Health Sciences Research Institute Germans Trias i Pujol (IGTP)-Universitat Autonoma de Barcelona, Crta. de Can Ruti, camí de les escoles s/n, 08916 Badalona, Barcelona, Spain
| | - Eudald Balagué
- Functional and Translational Neurogenetics Unit, Department of Neurosciences, Health Sciences Research Institute Germans Trias i Pujol (IGTP)-Universitat Autonoma de Barcelona, Crta. de Can Ruti, camí de les escoles s/n, 08916 Badalona, Barcelona, Spain
| | - Antoni Matilla-Dueñas
- Functional and Translational Neurogenetics Unit, Department of Neurosciences, Health Sciences Research Institute Germans Trias i Pujol (IGTP)-Universitat Autonoma de Barcelona, Crta. de Can Ruti, camí de les escoles s/n, 08916 Badalona, Barcelona, Spain
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15
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Ataxin-1 regulates proliferation of hippocampal neural precursors. Neuroscience 2016; 322:54-65. [PMID: 26876606 DOI: 10.1016/j.neuroscience.2016.02.011] [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: 10/29/2015] [Revised: 01/11/2016] [Accepted: 02/03/2016] [Indexed: 02/01/2023]
Abstract
Polyglutamine expansion in the protein ATAXIN-1 (ATXN1) causes spinocerebellar ataxia type 1 (SCA1), an inherited neurodegenerative disease characterized by motor deficits, cognitive impairment and depression. Although ubiquitously expressed, mutant ATXN1 causes neurodegeneration primarily in the cerebellum, which is responsible for the observed motor deficits. The role of ATXN1 outside of the cerebellum and the causes of cognitive deficits and depression in SCA1 are less understood. In this study, we demonstrate a novel role of ATXN1 in the hippocampus as a regulator of adult neurogenesis. Adult hippocampal neurogenesis is the process of generating new hippocampal neurons and is linked to cognition and mood. We found that loss of ATXN1 causes a decrease in hippocampal neurogenesis in ATXN1 null (Atxn1(-/-)) mice. This decrease was caused by reduced proliferation of neural precursors in the hippocampus of Atxn1(-/-) mice, and persisted even when Atxn1(-/-) hippocampal neural precursors were removed from their natural environment and grown in vitro, suggesting that ATXN1 affects proliferation in a cell-autonomous manner. Moreover, expression of ATXN1 with a pathological polyglutamine (polyQ) expansion in wild-type neural precursor cells inhibited their proliferation. Our data establish a novel role for ATXN1 in the hippocampus as an intrinsic regulator of precursor cell proliferation, and suggest a mechanism by which polyQ expansion and loss of ATXN1 affect hippocampal function, potentially contributing to cognitive deficits and depression. These results indicate that while depletion of ATXN1 is a promising therapeutic approach to treat the cerebellar aspects of SCA1, this approach should be employed with caution given the potential for side effects on hippocampal function with loss of wild-type ATXN1.
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16
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Schwarz R, Reif A, Scholz CJ, Weissflog L, Schmidt B, Lesch KP, Jacob C, Reichert S, Heupel J, Volkert J, Kopf J, Hilscher M, Weber H, Kittel-Schneider S. A preliminary study on methylphenidate-regulated gene expression in lymphoblastoid cells of ADHD patients. World J Biol Psychiatry 2015; 16:180-9. [PMID: 25162476 DOI: 10.3109/15622975.2014.948064] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVES Methylphenidate (MPH) is a commonly used stimulant medication for treating attention-deficit/hyperactivity disorder (ADHD). Besides inhibiting monoamine reuptake there is evidence that MPH also influences gene expression directly. METHODS We investigated the impact of MPH treatment on gene expression levels of lymphoblastoid cells derived from adult ADHD patients and healthy controls by hypothesis-free, genome-wide microarray analysis. Significant findings were subsequently confirmed by quantitative Real-Time PCR (qRT PCR) analysis. RESULTS The microarray analysis from pooled samples after correction for multiple testing revealed 138 genes to be marginally significantly regulated due to MPH treatment, and one gene due to diagnosis. By qRT PCR we could confirm that GUCY1B3 expression was differential due to diagnosis. We verified chronic MPH treatment effects on the expression of ATXN1, HEY1, MAP3K8 and GLUT3 in controls as well as acute treatment effects on the expression of NAV2 and ATXN1 specifically in ADHD patients. CONCLUSIONS Our preliminary results demonstrate MPH treatment differences in ADHD patients and healthy controls in a peripheral primary cell model. Our results need to be replicated in larger samples and also using patient-derived neuronal cell models to validate the contribution of those genes to the pathophysiology of ADHD and mode of action of MPH.
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Affiliation(s)
- Ricarda Schwarz
- Department of Psychiatry, Psychosomatics and Psychotherapy, University Hospital of Würzburg , Würzburg , Germany
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Beyond the glutamine expansion: influence of posttranslational modifications of ataxin-1 in the pathogenesis of spinocerebellar ataxia type 1. Mol Neurobiol 2014; 50:866-874. [PMID: 24752589 DOI: 10.1007/s12035-014-8703-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 03/31/2014] [Indexed: 01/05/2023]
Abstract
Posttranslational modifications are crucial mechanisms that modulate various cellular signaling pathways, and their dysregulation is associated with many human diseases. Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurodegenerative disease characterized by progressive ataxia, mild cognitive impairments, difficulty with speaking and swallowing, and respiratory failure. It is caused by the expansion of an unstable CAG trinucleotide repeat encoding a glutamine tract in Ataxin-1 (ATXN1). Although the expansion of the polyglutamine tract is the key determinant of the disease, protein domains outside of the polyglutamine tract and posttranslational modifications of ATXN1 significantly alter the neurotoxicity of SCA1. ATXN1 undergoes several posttranslational modifications, including phosphorylation, ubiquitination, sumoylation, and transglutamination. Such modifications can alter the stability of ATXN1 or its activity in the regulation of target gene expression and therefore contribute to SCA1 toxicity. This review outlines different types of posttranslational modifications in ATXN1 and discusses their potential regulatory mechanisms and effects on SCA1 pathogenesis. Finally, the manipulation of posttranslational modifications as a potential therapeutic approach will be discussed.
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Smeets CJLM, Verbeek DS. Cerebellar ataxia and functional genomics: Identifying the routes to cerebellar neurodegeneration. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2030-2038. [PMID: 24726947 DOI: 10.1016/j.bbadis.2014.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 03/25/2014] [Accepted: 04/02/2014] [Indexed: 12/20/2022]
Abstract
Cerebellar ataxias are progressive neurodegenerative disorders characterized by atrophy of the cerebellum leading to motor dysfunction, balance problems, and limb and gait ataxia. These include among others, the dominantly inherited spinocerebellar ataxias, recessive cerebellar ataxias such as Friedreich's ataxia, and X-linked cerebellar ataxias. Since all cerebellar ataxias display considerable overlap in their disease phenotypes, common pathological pathways must underlie the selective cerebellar neurodegeneration. Therefore, it is important to identify the molecular mechanisms and routes to neurodegeneration that cause cerebellar ataxia. In this review, we discuss the use of functional genomic approaches including whole-exome sequencing, genome-wide gene expression profiling, miRNA profiling, epigenetic profiling, and genetic modifier screens to reveal the underlying pathogenesis of various cerebellar ataxias. These approaches have resulted in the identification of many disease genes, modifier genes, and biomarkers correlating with specific stages of the disease. This article is part of a Special Issue entitled: From Genome to Function.
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Affiliation(s)
- C J L M Smeets
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - D S Verbeek
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
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Matilla-Dueñas A, Ashizawa T, Brice A, Magri S, McFarland KN, Pandolfo M, Pulst SM, Riess O, Rubinsztein DC, Schmidt J, Schmidt T, Scoles DR, Stevanin G, Taroni F, Underwood BR, Sánchez I. Consensus paper: pathological mechanisms underlying neurodegeneration in spinocerebellar ataxias. CEREBELLUM (LONDON, ENGLAND) 2014; 13:269-302. [PMID: 24307138 PMCID: PMC3943639 DOI: 10.1007/s12311-013-0539-y] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Intensive scientific research devoted in the recent years to understand the molecular mechanisms or neurodegeneration in spinocerebellar ataxias (SCAs) are identifying new pathways and targets providing new insights and a better understanding of the molecular pathogenesis in these diseases. In this consensus manuscript, the authors discuss their current views on the identified molecular processes causing or modulating the neurodegenerative phenotype in spinocerebellar ataxias with the common opinion of translating the new knowledge acquired into candidate targets for therapy. The following topics are discussed: transcription dysregulation, protein aggregation, autophagy, ion channels, the role of mitochondria, RNA toxicity, modulators of neurodegeneration and current therapeutic approaches. Overall point of consensus includes the common vision of neurodegeneration in SCAs as a multifactorial, progressive and reversible process, at least in early stages. Specific points of consensus include the role of the dysregulation of protein folding, transcription, bioenergetics, calcium handling and eventual cell death with apoptotic features of neurons during SCA disease progression. Unresolved questions include how the dysregulation of these pathways triggers the onset of symptoms and mediates disease progression since this understanding may allow effective treatments of SCAs within the window of reversibility to prevent early neuronal damage. Common opinions also include the need for clinical detection of early neuronal dysfunction, for more basic research to decipher the early neurodegenerative process in SCAs in order to give rise to new concepts for treatment strategies and for the translation of the results to preclinical studies and, thereafter, in clinical practice.
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Affiliation(s)
- A Matilla-Dueñas
- Health Sciences Research Institute Germans Trias i Pujol (IGTP), Ctra. de Can Ruti, Camí de les Escoles s/n, Badalona, Barcelona, Spain,
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Menon RP, Soong D, de Chiara C, Holt M, McCormick JE, Anilkumar N, Pastore A. Mapping the self-association domains of ataxin-1: identification of novel non overlapping motifs. PeerJ 2014; 2:e323. [PMID: 24711972 PMCID: PMC3970802 DOI: 10.7717/peerj.323] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 03/07/2014] [Indexed: 12/13/2022] Open
Abstract
The neurodegenerative disease spinocerebellar ataxia type 1 (SCA1) is caused by aggregation and misfolding of the ataxin-1 protein. While the pathology correlates with mutations that lead to expansion of a polyglutamine tract in the protein, other regions contribute to the aggregation process as also non-expanded ataxin-1 is intrinsically aggregation-prone and forms nuclear foci in cell. Here, we have used a combined approach based on FRET analysis, confocal microscopy and in vitro techniques to map aggregation-prone regions other than polyglutamine and to establish the importance of dimerization in self-association/foci formation. Identification of aggregation-prone regions other than polyglutamine could greatly help the development of SCA1 treatment more specific than that based on targeting the low complexity polyglutamine region.
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Affiliation(s)
- Rajesh P Menon
- MRC National Institute for Medical Research, The Ridgeway , London , UK
| | - Daniel Soong
- Randall Division for Cell and Molecular Biophysics, New Hunt's House, King's College London , Guy's Campus, London , UK ; British Heart Foundation Centre of Research Excellence, King's College London , Denmark Hill Campus, London , UK
| | - Cesira de Chiara
- MRC National Institute for Medical Research, The Ridgeway , London , UK
| | - Mark Holt
- Randall Division for Cell and Molecular Biophysics, New Hunt's House, King's College London , Guy's Campus, London , UK
| | - John E McCormick
- MRC National Institute for Medical Research, The Ridgeway , London , UK
| | - Narayana Anilkumar
- British Heart Foundation Centre of Research Excellence, King's College London , Denmark Hill Campus, London , UK
| | - Annalisa Pastore
- MRC National Institute for Medical Research, The Ridgeway , London , UK ; Department of Molecular Neuroscience, Institute of Psychiatry, King's College London , Denmark Hill Campus, London , UK
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de Chiara C, Pastore A. Kaleidoscopic protein-protein interactions in the life and death of ataxin-1: new strategies against protein aggregation. Trends Neurosci 2014; 37:211-8. [PMID: 24636457 PMCID: PMC3988977 DOI: 10.1016/j.tins.2014.02.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 01/26/2014] [Accepted: 02/06/2014] [Indexed: 12/11/2022]
Abstract
Understanding how proteins protect themselves from aberrant aggregation is of primary interest for understanding basic biology, protein biochemistry, and human disease. We discuss the paradigmatic example of ataxin-1 (Atx1), the protein responsible for neurodegenerative spinocerebellar ataxia type 1 (SCA1). This disease is part of the increasing family of pathologies caused by protein aggregation and misfolding. We discuss the importance of protein-protein interactions not only in the nonpathological function of Atx1 but also in protecting the protein from aggregation and misfolding. The lessons learned from Atx1 may lead to a more general understanding of the cell's protective strategies against aggregation. The obtained knowledge may suggest a new perspective for designing specific therapeutic strategies for the cure of misfolding diseases.
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Affiliation(s)
- Cesira de Chiara
- National Institute for Medical Research (NIMR), Medical Research Council (MRC), The Ridgeway, London NW7 1AA, UK
| | - Annalisa Pastore
- Department of Clinical Neurosciences, King's College London, Denmark Hill Campus, London, UK.
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Protein-protein interactions as a strategy towards protein-specific drug design: the example of ataxin-1. PLoS One 2013; 8:e76456. [PMID: 24155902 PMCID: PMC3796545 DOI: 10.1371/journal.pone.0076456] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 08/26/2013] [Indexed: 11/20/2022] Open
Abstract
A main challenge for structural biologists is to understand the mechanisms that discriminate between molecular interactions and determine function. Here, we show how partner recognition of the AXH domain of the transcriptional co-regulator ataxin-1 is fine-tuned by a subtle balance between self- and hetero-associations. Ataxin-1 is the protein responsible for the hereditary spinocerebellar ataxia type 1, a disease linked to protein aggregation and transcriptional dysregulation. Expansion of a polyglutamine tract is essential for ataxin-1 aggregation, but the sequence-wise distant AXH domain plays an important aggravating role in the process. The AXH domain is also a key element for non-aberrant function as it intervenes in interactions with multiple protein partners. Previous data have shown that AXH is dimeric in solution and forms a dimer of dimers when crystallized. By solving the structure of a complex of AXH with a peptide from the interacting transcriptional repressor CIC, we show that the dimer interface of AXH is displaced by the new interaction and that, when blocked by the CIC peptide AXH aggregation and misfolding are impaired. This is a unique example in which palindromic self- and hetero-interactions within a sequence with chameleon properties discriminate the partner. We propose a drug design strategy for the treatment of SCA1 that is based on the information gained from the AXH/CIC complex.
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Sánchez I, Piñol P, Corral-Juan M, Pandolfo M, Matilla-Dueñas A. A novel function of Ataxin-1 in the modulation of PP2A activity is dysregulated in the spinocerebellar ataxia type 1. Hum Mol Genet 2013; 22:3425-37. [PMID: 23630944 DOI: 10.1093/hmg/ddt197] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
An expansion of glutamines within the human ataxin-1 protein underlies spinocerebellar ataxia type 1 (SCA1), a dominantly inherited neurodegenerative disorder characterized by ataxia and loss of cerebellar Purkinje neurons. Although the mechanisms linking the mutation to the disease remain unclear, evidence indicates that it involves a combination of both gain and loss of functions of ataxin-1. We previously showed that the mutant ataxin-1 interacts with Anp32a, a potent and selective PP2A inhibitor, suggesting a role of PP2A in SCA1. Herein, we found a new function of ataxin-1: the modulation of Pp2a activity and the regulation of its holoenzyme composition, with the polyglutamine mutation within Atxn1 altering this function in the SCA1 mouse cerebellum before disease onset. We show that ataxin-1 enhances Pp2a-bβ expression and down-regulates Anp32a levels without affecting post-translational modifications of Pp2a catalytic subunit (Pp2a-c) known to regulate Pp2a activity. In contrast, mutant Atxn1 induces a decrease in Y307-phosphorylation in Pp2a-c, known to enhance its activity, while reducing Pp2a-b expression and inhibiting Anp32a levels. qRT-PCR and chromatin immunoprecipitation analyses show that ataxin-1-mediated regulations of the Pp2a-bβ subunit, specifically bβ2, and of Anp32a occur at the transcriptional level. The Pp2a pathway alterations were confirmed by identified phosphorylation changes of the known Pp2a-substrates, Erk2 and Gsk3β. Similarly, mutant ataxin-1-expressing SH-SY5Y cells exhibit abnormal neuritic morphology, decreased levels of both PP2A-Bβ and ANP32A, and PP2A pathway alterations, all of which are ameliorated by overexpressing ANP32A. Our results point to dysregulation of this newly assigned function of ataxin-1 in SCA1 uncovering new potential targets for therapy.
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Affiliation(s)
- Ivelisse Sánchez
- Basic, Translational and Molecular Neurogenetics Research Unit in Neurosciences, Health Sciences Research Institute Germans Trias y Pujol (IGTP), Badalona, Barcelona, Spain
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Gozen O, Balkan B, Yildirim E, Koylu EO, Pogun S. The epigenetic effect of nicotine on dopamine D1 receptor expression in rat prefrontal cortex. Synapse 2013; 67:545-52. [PMID: 23447334 DOI: 10.1002/syn.21659] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 02/22/2013] [Indexed: 12/14/2022]
Abstract
Nicotine is a highly addictive drug and exerts its effect partially through causing dopamine release, thereby increasing intrasynaptic dopamine levels in the brain reward systems. Dopaine D1 receptor (DRD1) mRNAs and receptors are localized in reward-related brain regions, which receive cholinergic input. The aim of this study is to evaluate whether nicotine administration affects the expression of DRD1s, and if so, whether epigenetic mechanisms, such as histone acetylation, are involved. Twenty Male Sprague Dawley rats received nicotine (0.4 mg/kg/day, s.c.) or saline injections for 15 days. After nicotine/saline treatment, rats were perfused with saline; prefrontal cortex (PFC), corpus striatum (STR), and ventral tegmental area (VTA) were dissected. Homogenates were divided into two parts for total RNA isolation and histone H4 acetylation studies. DRD1 mRNA expression was significantly higher in the PFC of the nicotine-treated group compared with controls; similar trends were observed in the VTA and STR. To study epigenetic regulation, the 2kb upstream region of the DRD1 gene promoter was investigated for histone H4 acetylation in PFC samples. After chromatin immunoprecipitation with anti-acetyl histone H4 antibody, we found an increase in histone acetylation by two different primer pairs which amplified the -1365 to -1202 (P < 0.005) and -170 to +12 (P < 0.05) upstream regions of the DRD1 promoter. Our results suggest that intermittent subcutaneous nicotine administration increases the expression of DRD1 mRNA in the PFC of rats, and this increase may be due to changes in histone H4 acetylation of the 2kb promoter of the DRD1 gene.
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Affiliation(s)
- Oguz Gozen
- Ege University School of Medicine Department of Physiology, Izmir, Turkey.
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Kasumu A, Bezprozvanny I. Deranged calcium signaling in Purkinje cells and pathogenesis in spinocerebellar ataxia 2 (SCA2) and other ataxias. THE CEREBELLUM 2012; 11:630-9. [PMID: 20480274 DOI: 10.1007/s12311-010-0182-9] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Spinocerebellar ataxias (SCAs) constitute a heterogeneous group of more than 30 autosomal-dominant genetic and neurodegenerative disorders. SCAs are generally characterized by progressive ataxia and cerebellar atrophy. Although all SCA patients present with the phenotypic overlap of cerebellar atrophy and ataxia, 17 different gene loci have so far been implicated as culprits in these SCAs. It is not currently understood how mutations in these 17 proteins lead to the cerebellar atrophy and ataxia. Several pathogenic mechanisms have been studied in SCAs but there is yet to be a promising target for successful treatment of SCAs. Emerging research suggests that a fundamental cellular signaling pathway is disrupted by a majority of these mutated genes, which could explain the characteristic death of Purkinje cells, cerebellar atrophy, and ataxia that occur in many SCAs. We propose that mutations in SCA genes cause disruptions in multiple cellular pathways but the characteristic SCA pathogenesis does not begin until calcium signaling pathways are disrupted in cerebellar Purkinje cells either as a result of an excitotoxic increase or a compensatory suppression of calcium signaling. We argue that disruptions in Purkinje cell calcium signaling lead to initial cerebellar dysfunction and ataxic sympoms and eventually proceed to Purkinje cell death. Here, we discuss a calcium hypothesis of Purkinje cell neurodegeneration in SCAs by primarily focusing on an example of spinocerebellar ataxia 2 (SCA2). We will also present evidence linking deranged calcium signaling to the pathogenesis of other SCAs (SCA1, 3, 5, 6, 14, 15/16) that lead to significant Purkinje cell dysfunction and loss in patients.
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Affiliation(s)
- Adebimpe Kasumu
- Department of Physiology, UT Southwestern Medical Center at Dallas, Texas, USA
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Menon RP, Soong D, de Chiara C, Holt MR, Anilkumar N, Pastore A. The importance of serine 776 in Ataxin-1 partner selection: a FRET analysis. Sci Rep 2012; 2:919. [PMID: 23213356 PMCID: PMC3513968 DOI: 10.1038/srep00919] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 09/17/2012] [Indexed: 11/25/2022] Open
Abstract
Anomalous expansion of a polymorphic tract in Ataxin-1 causes the autosomal dominant spinocerebellar ataxia type 1. In addition to polyglutamine expansion, requirements for development of pathology are phosphorylation of serine 776 in Ataxin-1 and nuclear localization of the protein. The phosphorylation state of serine 776 is also crucial for selection of the Ataxin-1 multiple partners. Here, we have used FRET for an in cell study of the interaction of Ataxin-1 with the spliceosome-associated U2AF65 and the adaptor 14-3-3 proteins. Using wild-type Ataxin-1 and Ser776 mutants to a phosphomimetic aspartate and to alanine, we show that U2AF65 binds Ataxin-1 in a Ser776 phosphorylation independent manner whereas 14-3-3 interacts with phosphorylated wild-type Ataxin-1 but not with the mutants. These results indicate that Ser776 acts as the molecular switch that discriminates between normal and aberrant function and that phosphomimetics is not a generally valid approach whose applicability should be carefully validated.
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Affiliation(s)
- Rajesh P Menon
- MRC National Institute for Medical Research , The Ridgeway, London NW7 1AA UK.
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Jin J, Cheng Y, Zhang Y, Wood W, Peng Q, Hutchison E, Mattson MP, Becker KG, Duan W. Interrogation of brain miRNA and mRNA expression profiles reveals a molecular regulatory network that is perturbed by mutant huntingtin. J Neurochem 2012; 123:477-90. [PMID: 22906125 PMCID: PMC3472040 DOI: 10.1111/j.1471-4159.2012.07925.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 08/13/2012] [Accepted: 08/14/2012] [Indexed: 11/27/2022]
Abstract
Emerging evidence indicates that microRNAs (miRNAs) may play an important role in the pathogenesis of Huntington's disease (HD). To identify the individual miRNAs that are altered in HD and may therefore regulate a gene network underlying mutant huntingtin-induced neuronal dysfunction in HD, we performed miRNA array analysis combined with mRNA profiling in the cerebral cortex from N171-82Q HD mice. Expression profiles of miRNAs as well as mRNAs in HD mouse cerebral cortex were analyzed and confirmed at different stages of disease progression; the most significant changes of miRNAs in the cerebral cortex were also detected in the striatum of HD mice. Our results revealed a significant alteration of miR-200 family members, miR-200a, and miR-200c in the cerebral cortex and the striatum, at the early stage of disease progression in N171-82Q HD mice. We used a coordinated approach to integrate miRNA and mRNA profiling, and applied bioinformatics to predict a target gene network potentially regulated by these significantly altered miRNAs that might be involved in HD disease progression. Interestingly, miR-200a and miR-200c are predicted to target genes regulating synaptic function, neurodevelopment, and neuronal survival. Our results suggest that altered expression of miR-200a and miR-200c may interrupt the production of proteins involved in neuronal plasticity and survival, and further investigation of the involvement of perturbed miRNA expression in HD pathogenesis is warranted, and may lead to reveal novel approaches for HD therapy.
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Affiliation(s)
- Jing Jin
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | - Yong Cheng
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | - Yongqing Zhang
- Gene Expression and Genomics Unit Research Resources Branch, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - William Wood
- Gene Expression and Genomics Unit Research Resources Branch, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - Qi Peng
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | - Emmette Hutchison
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - Mark P. Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | - Kevin G. Becker
- Gene Expression and Genomics Unit Research Resources Branch, National Institute on Aging Intramural Research Program, Baltimore, MD 21224
| | - Wenzhen Duan
- Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287
- Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287
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Abstract
Polyglutamine neurodegenerative diseases result from the expansion of a trinucleotide CAG repeat, encoding a polyglutamine tract in the disease-causing protein. The process by which each polyglutamine protein exerts its toxicity is complex, involving a variety of mechanisms including transcriptional dysregulation, proteasome impairment and mitochondrial dysfunction. Thus, the most effective and widely applicable therapies are likely to be those designed to eliminate production of the mutant protein upstream of these deleterious effects. RNA-based approaches represent promising therapeutic strategies for polyglutamine diseases, offering the potential to suppress gene expression in a sequence-specific manner at the transcriptional and post-transcriptional levels. In particular, gene silencing therapies capable of discrimination between mutant and wildtype alleles, based on disease-linked polymorphisms or CAG repeat length, might prove crucial in cases where a loss of wild type function is deleterious. Novel methods, such as gene knockdown and replacement, seek to eliminate the technical difficulties associated with allele-specific silencing by avoiding the need to target specific mutations. With a variety of RNA technologies currently being developed to target multiple facets of polyglutamine pathogenesis, the emergence of an effective therapy seems imminent. However, numerous technical obstacles associated with design, discrimination and delivery must be overcome before RNA therapy can be effectively applied in the clinical setting.
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Vig PJ, Wei J, Shao Q, Lopez ME, Halperin R, Gerber J. Suppression of Calbindin-D28k Expression Exacerbates SCA1 Phenotype in a Disease Mouse Model. THE CEREBELLUM 2011; 11:718-32. [DOI: 10.1007/s12311-011-0323-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Vig PJS, Hearst S, Shao Q, Lopez ME, Murphy HA, Safaya E. Glial S100B protein modulates mutant ataxin-1 aggregation and toxicity: TRTK12 peptide, a potential candidate for SCA1 therapy. THE CEREBELLUM 2011; 10:254-66. [PMID: 21384195 DOI: 10.1007/s12311-011-0262-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Non-cell autonomous involvement of glial cells in the pathogenesis of polyglutamine diseases is gaining recognition in the ataxia field. We previously demonstrated that Purkinje cells (PCs) in polyglutamine disease spinocerebellar ataxia-1 (SCA1) contain cytoplasmic vacuoles rich in Bergmann glial protein S100B. The vacuolar formation in SCA1 PCs is accompanied with an abnormal morphology of dendritic spines. In addition, S100B messenger RNA (mRNA) expression levels are significantly high in the cerebella of asymptomatic SCA1 transgenic (Tg) mice and increase further with age when compared with the age-matched wild-type animals. This higher S100B mRNA expression positively correlates with an increase in the number of vacuoles. To further characterize the function of S100B in SCA1 pathology, we explored the effects of S100B protein on GFP-ataxin-1 (ATXN1) with expanded polyglutamines [82Q] in HEK stable cell line. Externally added S100B protein to these cells induced S100B-positive vacuoles similar to those seen in SCA1 PCs in vivo. Further, we found that both externally added and internally expressed S100B significantly reduced GFP-ATXN1[82Q] inclusion body formation. In contrast, the addition of S100B inhibitory peptide TRTK12 reversed S100B-mediated effects. Interestingly, in SCA1 Tg mice, PCs containing S100B vacuoles also showed the lack of nuclear inclusions, whereas PCs without vacuoles contained nuclear inclusions. Additionally, TRTK12 treatment reduced abnormal dendritic growth and morphology of PCs in cerebellar slice cultures prepared from SCA1 Tg mice. Moreover, intranasal administration of TRTK12 to SCA1 Tg mice reduced cerebellar S100B levels in the particulate fractions, and these mice displayed a significant improvement in their performance deficit on the Rotarod test. Taken together, our results suggest that glial S100B may augment degenerative changes in SCA1 PCs by modulating mutant ataxin-1 toxicity/solubility through an unknown signaling pathway.
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Affiliation(s)
- Parminder J S Vig
- Department of Neurology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.
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Chen YC, Gatchel JR, Lewis RW, Mao CA, Grant PA, Zoghbi HY, Dent SYR. Gcn5 loss-of-function accelerates cerebellar and retinal degeneration in a SCA7 mouse model. Hum Mol Genet 2011; 21:394-405. [PMID: 22002997 DOI: 10.1093/hmg/ddr474] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Spinocerebellar ataxia type 7 (SCA7) is a neurodegenerative disease caused by expansion of a CAG repeat encoding a polyglutamine tract in ATXN7, a component of the SAGA histone acetyltransferase (HAT) complex. Previous studies provided conflicting evidence regarding the effects of polyQ-ATXN7 on the activity of Gcn5, the HAT catalytic subunit of SAGA. Here, we report that reducing Gcn5 expression accelerates both cerebellar and retinal degeneration in a mouse model of SCA7. Deletion of Gcn5 in Purkinje cells in mice expressing wild-type (wt) Atxn7, however, causes only mild ataxia and does not lead to the early lethality observed in SCA7 mice. Reduced Gcn5 expression strongly enhances retinopathy in SCA7 mice, but does not affect the known transcriptional targets of Atxn7, as expression of these genes is not further altered by Gcn5 depletion. These findings demonstrate that loss of Gcn5 functions can contribute to the time of onset and severity of SCA7 phenotypes, and suggest that non-transcriptional functions of SAGA may play a role in neurodegeneration in this disease.
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Affiliation(s)
- Yi Chun Chen
- Department of Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center Science Park, Smithville, TX 78957, USA
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Ren J, Jegga AG, Zhang M, Deng J, Liu J, Gordon CB, Aronow BJ, Lu LJ, Zhang B, Ma J. A Drosophila model of the neurodegenerative disease SCA17 reveals a role of RBP-J/Su(H) in modulating the pathological outcome. Hum Mol Genet 2011; 20:3424-36. [PMID: 21653638 DOI: 10.1093/hmg/ddr251] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Expanded polyglutamine (polyQ) tract in the human TATA-box-binding protein (hTBP) causes the neurodegenerative disease spinocerebellar ataxia 17 (SCA17). To investigate the pathological effects of polyQ expansion, we established a SCA17 model in Drosophila. Similar to SCA17 patients, transgenic flies expressing a mutant hTBP protein with an expanded polyQ tract (hTBP80Q) exhibit progressive neurodegeneration, late-onset locomotor impairment and shortened lifespan. Microarray analysis reveals that hTBP80Q causes widespread and time-dependent transcriptional dysregulation in Drosophila. In a candidate screen for genetic modifiers, we identified RBP-J/Su(H), a transcription factor that contains Q/N-rich domains and participates in Notch signaling. Knockdown of Su(H) by RNAi further enhances hTBP80Q-induced eye defects, whereas overexpression of Su(H) suppresses such defects. While the Su(H) transcript level is not significantly altered in hTBP80Q-expressing flies, genes that contain Su(H)-binding sites are among those that are dysregulated. We further show that hTBP80Q interacts more efficiently with Su(H) than wild-type hTBP, suggesting that a reduction in the fraction of Su(H) available for its normal cellular functions contributes to hTBP80Q-induced phenotypes. While the Notch signaling pathway has been implicated in several neurological disorders, our study suggests a possibility that the activity of its nuclear component RBP-J/Su(H) may modulate the pathological progression in SCA17 patients.
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Affiliation(s)
- Jie Ren
- Key Laboratory of Cell Proliferation and Differentiation of Ministry of Education, Center of Developmental Biology and Genetics, College of Life Sciences, Peking University, Beijing 100871, PR China
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Gehrking KM, Andresen JM, Duvick L, Lough J, Zoghbi HY, Orr HT. Partial loss of Tip60 slows mid-stage neurodegeneration in a spinocerebellar ataxia type 1 (SCA1) mouse model. Hum Mol Genet 2011; 20:2204-12. [PMID: 21427130 PMCID: PMC3090197 DOI: 10.1093/hmg/ddr108] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Spinocerebellar ataxia type 1 (SCA1) is one of nine dominantly inherited neurodegenerative diseases caused by polyglutamine tract expansion. In SCA1, the expanded polyglutamine tract is in the ataxin-1 (ATXN1) protein. ATXN1 is part of an in vivo complex with retinoid acid receptor-related orphan receptor alpha (Rora) and the acetyltransferase tat-interactive protein 60 kDa (Tip60). ATXN1 and Tip60 interact directly via the ATXN1 and HMG-box protein 1 (AXH) domain of ATXN1. Moreover, the phospho-mimicking Asp amino acid at position 776, previously shown to enhance pathogenesis, increases the ability of ATXN1 to interact with Tip60. Using a genetic approach, the biological relevance of the ATXN1/Tip60 interaction was assessed by crossing ATXN1[82Q] mice with Tip60(+/-)animals. Partial Tip60 loss increased Rora and Rora-mediated gene expression and delayed ATXN1[82]-mediated cerebellar degeneration during mid-stage disease progression. These results suggested a specific, temporal role for Tip60 during disease progression. We also showed that genetic background modulated ATXN1[82Q]-induced phenotypes. Of interest, these latter studies showed that some phenotypes are enhanced on a mixed background while others are suppressed.
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Affiliation(s)
- Kristin M Gehrking
- Institute of Human Genetics and Institute of Translational Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
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Ataxin-1 occupies the promoter region of E-cadherin in vivo and activates CtBP2-repressed promoter. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:713-22. [PMID: 21315774 DOI: 10.1016/j.bbamcr.2011.01.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 01/25/2011] [Accepted: 01/27/2011] [Indexed: 12/11/2022]
Abstract
Ataxin-1 is a polyglutamine protein of unknown function that is encoded by the ATXN1 gene in humans. To gain insight into the function of ataxin-1, we sought to identify proteins that interact with ataxin-1 through yeast two-hybrid screening. In this study, transcriptional corepressor CtBP2 was identified as a protein that interacted with ataxin-1. CtBP2 and ataxin-1 colocalized in the nucleus of mammalian cells. Since the E-cadherin promoter is a target of CtBP-mediated repression, the relationship between ataxin-1 and the E-cadherin promoter was investigated. Chromatin immunoprecipitation assays showed that CtBP2 and ataxin-1 were recruited to the E-cadherin promoter in mammalian cells. Luciferase assays using E-cadherin promoter reporter constructs revealed that the luciferase activity was enhanced as the level of ataxin-1 protein expression increased. CtBP2 overexpression decreased E-cadherin expression, but expression of ataxin-1 inversely increased the mRNA and protein levels of endogenous E-cadherin. Interestingly, siRNA experiments showed that the transcriptional activation of ataxin-1 was associated with the presence of CtBP2. This study demonstrates that ataxin-1 occupies the promoter region of E-cadherin in vivo and that ataxin-1 activates the promoter in a CtBP2-mediated transcriptional regulation manner. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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Bezprozvanny I. Role of inositol 1,4,5-trisphosphate receptors in pathogenesis of Huntington's disease and spinocerebellar ataxias. Neurochem Res 2011; 36:1186-97. [PMID: 21210219 DOI: 10.1007/s11064-010-0393-y] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/27/2010] [Indexed: 11/28/2022]
Abstract
Huntington's disease (HD) and spinocerebellar ataxias (SCAs) are autosomal-dominant neurodegenerative disorders. HD is caused by polyglutamine (polyQ) expansion in the amino-terminal region of a protein huntingtin (Htt) and primarily affects medium spiny striatal neurons (MSN). Many SCAs are caused by polyQ-expansion in ataxin proteins and primarily affect cerebellar Purkinje cells. The reasons for neuronal dysfunction and death in HD and SCAs remain poorly understood and no cure is available for the patients. Our laboratory discovered that mutant huntingtin, ataxin-2 and ataxin-3 proteins specifically bind to the carboxy-terminal region of the type 1 inositol 1,4,5-trisphosphate receptor (IP(3)R1), an intracellular Ca(2+) release channel. Moreover, we found that association of mutant huntingtin or ataxins with IP(3)R1 causes sensitization of IP(3)R1 to activation by IP(3) in planar lipid bilayers and in neuronal cells. These results suggested that deranged neuronal Ca(2+) signaling might play an important role in pathogenesis of HD, SCA2 and SCA3. In support of this idea, we demonstrated a connection between abnormal Ca(2+) signaling and neuronal cell death in experiments with HD, SCA2 and SCA3 transgenic mouse models. Additional data in the literature indicate that abnormal neuronal Ca(2+) signaling may also play an important role in pathogenesis of SCAl, SCA5, SCA6, SCA14 and SCA15/16. Based on these results I propose that IP(3)R and other Ca(2+) signaling proteins should be considered as potential therapeutic targets for treatment of HD and SCAs.
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Affiliation(s)
- Ilya Bezprozvanny
- Department of Physiology, ND12.200AA, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9040, USA.
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36
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He XH, Lin F, Qin ZH. Current understanding on the pathogenesis of polyglutamine diseases. Neurosci Bull 2010; 26:247-56. [PMID: 20502504 DOI: 10.1007/s12264-010-0113-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Polyglutamine (polyQ) diseases are a family of neurodegenerative disorders including Huntington's disease, spinobulbar muscular atrophy, dentatorubral-pallidoluysian atrophy and several spinocerebellar ataxias. polyQ diseases are caused by abnormal expansion of CAG repeats in certain genes. The expanded CAG repeats are then translated into a series of abnormally expanded polyQ tracts. Such polyQ tracts may induce misfolding of the disease-causing proteins. The present review mainly focuses on the common characteristics of the pathogenesis of these polyQ diseases, including conformational transition of proteins and its influence on the function of these proteins, the correlation between decreased ability of proteolysis and late-onset polyQ diseases, and the relationship between wide expression of disease-causing proteins and selective neuronal death.
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Affiliation(s)
- Xiao-Hui He
- Department of Pharmacology and Laboratory of Aging and Nervous Diseases, Soochow University School of Medicine, Suzhou 215123, China
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Hearst SM, Lopez ME, Shao Q, Liu Y, Vig PJS. Dopamine D2 receptor signaling modulates mutant ataxin-1 S776 phosphorylation and aggregation. J Neurochem 2010; 114:706-16. [PMID: 20477910 PMCID: PMC2921766 DOI: 10.1111/j.1471-4159.2010.06791.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Spinocerebellar ataxia 1 (SCA1) is a dominantly inherited neurodegenerative disease associated with progressive ataxia resulting from the loss of cerebellar Purkinje cells (PCs) and neurons in the brainstem. In PCs of SCA1 transgenic mice, the disease causing ataxin-1 protein mediates the formation of S100B containing cytoplasmic vacuoles and further self-aggregates to form intranuclear inclusions. The exact function of the ataxin-1 protein is not fully understood. However, the aggregation and neurotoxicity of the mutant ataxin-1 protein is dependent on the phosphorylation at serine 776 (S776). Although protein kinase A (PKA) has been implicated as the S776 kinase, the mechanism of PKA/ataxin-1 regulation in SCA1 is still not clear. We propose that a dopamine D(2) receptor (D2R)/S100B pathway may be involved in modulating PKA activity in PCs. Using a D2R/S100B HEK stable cell line transiently transfected with GFP-ataxin-1[82Q], we demonstrate that stimulation of the D2R/S100B pathway caused a reduction in mutant ataxin-1 S776 phosphorylation and ataxin-1 aggregation. Activation of PKA by forskolin resulted in an enhanced S776 phosphorylation and increased ataxin-1 nuclear aggregation, which was suppressed by treatment with D2R agonist bromocriptine and PKA inhibitor H89. Furthermore, treating SCA1 transgenic PC slice cultures with forskolin induced neurodegenerative morphological abnormalities in PC dendrites consistent with those observed in vivo. Taken together our data support a mechanism where PKA dependent mutant ataxin-1 phosphorylation and aggregation can be regulated by D2R/S100B signaling.
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Affiliation(s)
- SM Hearst
- Department of Neurology, University of Mississippi Medical Center, Jackson, MS
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, MS
| | - ME Lopez
- Department of Neurology, University of Mississippi Medical Center, Jackson, MS
| | - Q Shao
- Department of Neurology, University of Mississippi Medical Center, Jackson, MS
| | - Y Liu
- Department of Behavioral Neuroscience, Oregon Health & Science University and Portland Veterans Affairs Medical Center, Portland, OR
| | - PJS Vig
- Department of Neurology, University of Mississippi Medical Center, Jackson, MS
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, MS
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Partial loss of ataxin-1 function contributes to transcriptional dysregulation in spinocerebellar ataxia type 1 pathogenesis. PLoS Genet 2010; 6:e1001021. [PMID: 20628574 PMCID: PMC2900305 DOI: 10.1371/journal.pgen.1001021] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 06/08/2010] [Indexed: 12/29/2022] Open
Abstract
Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurodegenerative disease caused by expansion of a CAG repeat that encodes a polyglutamine tract in ATAXIN1 (ATXN1). Molecular and genetic data indicate that SCA1 is mainly caused by a gain-of-function mechanism. However, deletion of wild-type ATXN1 enhances SCA1 pathogenesis, whereas increased levels of an evolutionarily conserved paralog of ATXN1, Ataxin 1-Like, ameliorate it. These data suggest that a partial loss of ATXN1 function contributes to SCA1. To address this possibility, we set out to determine if the SCA1 disease model (Atxn1154Q/+ mice) and the loss of Atxn1 function model (Atxn1−/− mice) share molecular changes that could potentially contribute to SCA1 pathogenesis. To identify transcriptional changes that might result from loss of function of ATXN1 in SCA1, we performed gene expression microarray studies on cerebellar RNA from Atxn1−/− and Atxn1154Q/+ cerebella and uncovered shared gene expression changes. We further show that mild overexpression of Ataxin-1-Like rescues several of the molecular and behavioral defects in Atxn1−/− mice. These results support a model in which Ataxin 1-Like overexpression represses SCA1 pathogenesis by compensating for a partial loss of function of Atxn1. Altogether, these data provide evidence that partial loss of Atxn1 function contributes to SCA1 pathogenesis and raise the possibility that loss-of-function mechanisms contribute to other dominantly inherited neurodegenerative diseases. Spinocerebellar Ataxia type 1 (SCA1) is one of nine neurodegenerative diseases caused by an increase in the number of the amino acid glutamine in their respective proteins. Genetic studies have pointed to the fact that the glutamine expansion in Ataxin-1 causes SCA1 by causing Ataxin-1 to gain some function(s). Here, we demonstrate that in addition to the toxic gain-of-function mechanism, partial loss of the normal functions of Ataxin-1 contributes to SCA1. Ataxin-1 forms protein complexes with Capicua, a protein that silences expression of other genes, and we found that in SCA1 mouse models the levels of these complexes are reduced, resulting in increased expression of some genes. We also demonstrate that increased levels of Ataxin-1-Like, a protein that is similar to Ataxin-1 and protects against mutant Ataxin-1 in mice, rescues molecular and behavioral defects in mice deficient in Ataxin-1. These results show that Ataxin-1-Like compensates for loss of Ataxin-1 and that Ataxin-1 and Ataxin-1-Like share some normal functions. Together, these findings suggest that rescue of SCA1 symptoms by Ataxin-1-Like could be partly due to restoration of lost normal functions of Ataxin-1 in mice that express the mutant polyglutamine-expanded Ataxin-1.
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Zhang C, Browne A, Child D, Divito JR, Stevenson JA, Tanzi RE. Loss of function of ATXN1 increases amyloid beta-protein levels by potentiating beta-secretase processing of beta-amyloid precursor protein. J Biol Chem 2010; 285:8515-26. [PMID: 20097758 DOI: 10.1074/jbc.m109.079079] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Alzheimer disease (AD) is a devastating neurodegenerative disease with complex and strong genetic inheritance. Four genes have been established to either cause familial early onset AD (APP, PSEN1, and PSEN2) or to increase susceptibility for late onset AD (APOE). To date approximately 80% of the late onset AD genetic variance remains elusive. Recently our genome-wide association screen identified four novel late onset AD candidate genes. Ataxin 1 (ATXN1) is one of these four AD candidate genes and has been indicated to be the disease gene for spinocerebellar ataxia type 1, which is also a neurodegenerative disease. Mounting evidence suggests that the excessive accumulation of Abeta, the proteolytic product of beta-amyloid precursor protein (APP), is the primary AD pathological event. In this study, we ask whether ATXN1 may lead to AD pathogenesis by affecting Abeta and APP processing utilizing RNA interference in a human neuronal cell model and mouse primary cortical neurons. We show that knock-down of ATXN1 significantly increases the levels of both Abeta40 and Abeta42. This effect could be rescued with concurrent overexpression of ATXN1. Moreover, overexpression of ATXN1 decreased Abeta levels. Regarding the underlying molecular mechanism, we show that the effect of ATXN1 expression on Abeta levels is modulated via beta-secretase cleavage of APP. Taken together, ATXN1 functions as a genetic risk modifier that contributes to AD pathogenesis through a loss-of-function mechanism by regulating beta-secretase cleavage of APP and Abeta levels.
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Affiliation(s)
- Can Zhang
- Department of Neurology, Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Diseases, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129-2060, USA
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AF4 is a critical regulator of the IGF-1 signaling pathway during Purkinje cell development. J Neurosci 2010; 29:15366-74. [PMID: 20007461 DOI: 10.1523/jneurosci.5188-09.2009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Deregulation of the insulin-like growth factor 1 (IGF-1) signaling pathway is a recurrent finding in mouse models and human patients with cerebellar ataxia and thus represents a common pathological cascade in neuronal cell death that may be targeted for therapy. We have previously identified a point mutation in AF4, a transcription cofactor of RNA polymerase II elongation and chromatin remodeling, that causes progressive and highly specific Purkinje cell (PC) death in the ataxic mouse mutant robotic, leading to the accumulation of AF4 in PCs. Here we confirm that the spatiotemporal pattern of PC degeneration in the robotic cerebellum correlates with the specific profile of AF4 upregulation. To identify the underlying molecular pathways, we performed microarray gene expression analysis of PCs obtained by laser capture microdissection (LCM) at the onset of degeneration. Igf-1 was significantly downregulated in robotic PCs compared with wild-type controls before and throughout the degenerative process. Consistently, we observed a decrease in the activation of downstream signaling molecules including type 1 IGF receptor (IGF-1R) and the extracellular signal-regulated kinase (ERK) 1 and ERK2. Chromatin immunoprecipitation confirmed that Igf-1 is a direct and the first validated target of the AF4 transcriptional regulatory complex, and treatment of presymptomatic robotic mice with IGF-1 indeed markedly delayed the progression of PC death. This study demonstrates that small changes in the levels of a single transcriptional cofactor can deleteriously affect normal cerebellum function and opens new avenues of research for the manipulation of the IGF-1 pathway in the treatment of cerebellar ataxia in humans.
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de Chiara C, Menon RP, Strom M, Gibson TJ, Pastore A. Phosphorylation of S776 and 14-3-3 binding modulate ataxin-1 interaction with splicing factors. PLoS One 2009; 4:e8372. [PMID: 20037628 PMCID: PMC2791216 DOI: 10.1371/journal.pone.0008372] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Accepted: 11/16/2009] [Indexed: 12/02/2022] Open
Abstract
Ataxin-1 (Atx1), a member of the polyglutamine (polyQ) expanded protein family, is responsible for spinocerebellar ataxia type 1. Requirements for developing the disease are polyQ expansion, nuclear localization and phosphorylation of S776. Using a combination of bioinformatics, cell and structural biology approaches, we have identified a UHM ligand motif (ULM), present in proteins associated with splicing, in the C-terminus of Atx1 and shown that Atx1 interacts with and influences the function of the splicing factor U2AF65 via this motif. ULM comprises S776 of Atx1 and overlaps with a nuclear localization signal and a 14-3-3 binding motif. We demonstrate that phosphorylation of S776 provides the molecular switch which discriminates between 14-3-3 and components of the spliceosome. We also show that an S776D Atx1 mutant previously designed to mimic phosphorylation is unsuitable for this aim because of the different chemical properties of the two groups. Our results indicate that Atx1 is part of a complex network of interactions with splicing factors and suggest that development of the pathology is the consequence of a competition of aggregation with native interactions. Studies of the interactions formed by non-expanded Atx1 thus provide valuable hints for understanding both the function of the non-pathologic protein and the causes of the disease.
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Affiliation(s)
- Cesira de Chiara
- National Institute for Medical Research, Medical Research Council, London, United Kingdom
| | - Rajesh P. Menon
- National Institute for Medical Research, Medical Research Council, London, United Kingdom
| | - Molly Strom
- National Institute for Medical Research, Medical Research Council, London, United Kingdom
| | - Toby J. Gibson
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Annalisa Pastore
- National Institute for Medical Research, Medical Research Council, London, United Kingdom
- * E-mail:
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Cellular and Molecular Pathways Triggering Neurodegeneration in the Spinocerebellar Ataxias. THE CEREBELLUM 2009; 9:148-66. [DOI: 10.1007/s12311-009-0144-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Shah AG, Friedman MJ, Huang S, Roberts M, Li XJ, Li S. Transcriptional dysregulation of TrkA associates with neurodegeneration in spinocerebellar ataxia type 17. Hum Mol Genet 2009; 18:4141-52. [PMID: 19643914 DOI: 10.1093/hmg/ddp363] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
TATA binding protein (TBP), a universal transcription factor, is broadly required by nuclear RNA polymerases for the initiation of transcription. TBP contains a polymorphic polyglutamine tract in its N-terminal region, and expansion of this tract leads to spinocerebellar ataxia type 17 (SCA17), one of nine dominantly inherited neurodegenerative diseases caused by polyglutamine expansion in the affected proteins. The expanded polyglutamine proteins are ubiquitously expressed, but cause selective and characteristic neurodegeneration in distinct brain regions in each disease. Unlike many other polyglutamine proteins, whose functions are not yet fully understood, TBP is a well-characterized transcription factor that is restricted to the nucleus. Thus, investigating how mutant TBP mediates neuropathology should help elucidate the mechanisms by which transcriptional dysregulation contributes to neuronal dysfunction and/or neurodegeneration in polyglutamine diseases. To this end, we characterized cellular and mouse models expressing polyQ-expanded TBP. The cell model exhibits characteristic features of neuronal dysfunction, including decreased cell viability and defective neurite outgrowth. We found that the high-affinity nerve growth factor receptor, TrkA, is down-regulated by mutant TBP in cells. Down-regulation of TrkA also occurs in the cerebellum of SCA17 transgenic mice prior to Purkinje cell degeneration. Mutant TBP binds more Sp1, reduces its occupancy of the TrkA promoter and inhibits the activity of the TrkA promoter. These findings suggest that the transcriptional down-regulation of TrkA by mutant TBP contributes to SCA17 pathogenesis.
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Affiliation(s)
- Anjali G Shah
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
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Kang S, Hong S. Molecular pathogenesis of spinocerebellar ataxia type 1 disease. Mol Cells 2009; 27:621-7. [PMID: 19572115 DOI: 10.1007/s10059-009-0095-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 06/19/2009] [Indexed: 01/21/2023] Open
Abstract
Spinocerebellar ataxia type 1 (SCA1) is an autosomal-dominant neurodegenerative disorder characterized by ataxia and progressive motor deterioration. SCA1 is associated with an elongated polyglutamine tract in ataxin-1, the SCA1 gene product. As summarized in this review, recent studies have clarified the molecular mechanisms of SCA1 pathogenesis and provided direction for future therapeutic approaches. The nucleus is the subcellular site where misfolded mutant ataxin-1 acts to cause SCA1 disease in the cerebellum. The role of these nuclear aggregates is the subject of intensive study. Additional proteins have been identified, whose conformational alterations occurring through interactions with the polyglutamine tract itself or non-polyglutamine regions in ataxin-1 are the cause of SCA-1 cytotoxicity. Therapeutic hope comes from the observations concerning the reduction of nuclear aggregation and alleviation of the pathogenic phenotype by the application of potent inhibitors and RNA interference.
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Affiliation(s)
- Seongman Kang
- Graduate School of Life Science and Biotechnology, Korea University, Seoul 136-701, Korea
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Huntingtin modulates transcription, occupies gene promoters in vivo, and binds directly to DNA in a polyglutamine-dependent manner. J Neurosci 2008; 28:10720-33. [PMID: 18923047 DOI: 10.1523/jneurosci.2126-08.2008] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Transcriptional dysregulation is a central pathogenic mechanism in Huntington's disease, a fatal neurodegenerative disorder associated with polyglutamine (polyQ) expansion in the huntingtin (Htt) protein. In this study, we show that mutant Htt alters the normal expression of specific mRNA species at least partly by disrupting the binding activities of many transcription factors which govern the expression of the dysregulated mRNA species. Chromatin immunoprecipitation (ChIP) demonstrates Htt occupation of gene promoters in vivo in a polyQ-dependent manner, and furthermore, ChIP-on-chip and ChIP subcloning reveal that wild-type and mutant Htt exhibit differential genomic distributions. Exon 1 Htt binds DNA directly in the absence of other proteins and alters DNA conformation. PolyQ expansion increases Htt-DNA interactions, with binding to recognition elements of transcription factors whose function is altered in HD. Together, these findings suggest mutant Htt modulates gene expression through abnormal interactions with genomic DNA, altering DNA conformation and transcription factor binding.
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Benn CL, Fox H, Bates GP. Optimisation of region-specific reference gene selection and relative gene expression analysis methods for pre-clinical trials of Huntington's disease. Mol Neurodegener 2008; 3:17. [PMID: 18954449 PMCID: PMC2584034 DOI: 10.1186/1750-1326-3-17] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Accepted: 10/27/2008] [Indexed: 12/01/2022] Open
Abstract
Background Transcriptional dysregulation is an early, key pathogenic mechanism in Huntington's disease (HD). Therefore, gene expression analyses have biomarker potential for measuring therapeutic efficacy in pre-clinical trials, particularly those aimed at correcting gene expression abnormalities. Housekeeping genes are commonly used as endogenous references in gene expression studies. However, a systematic study comparing the suitability of candidate reference genes for use in HD mouse models has not been performed. To remedy this situation, 12 housekeeping genes were examined to identify suitable reference genes for use in expression assays. Results We found that commonly used reference genes are dysregulated at later time points in the R6/2 mouse model of HD. Therefore, in order to reliably measure gene expression changes for use as pre-clinical trial biomarkers, we set out to identify suitable reference genes for use in R6/2 mice. The expression of potential reference genes was examined in striatum, cortex and cerebellum from 15 week old R6/2 and matched wild-type littermates. Expression levels of candidate reference genes varied according to genotype and brain region. GeNorm software was used to identify the three most stably expressed genes for each brain region. Relative quantification methods using the geometric mean of three reference genes for normalisation enables accurate determination of gene expression levels in wild-type and R6/2 mouse brain regions. Conclusion Our study has identified a reproducible, reliable method by which we able to accurately determine the relative expression level of target genes in specific brain regions, thus increasing the potential of gene expression analysis as a biomarker in HD pre-clinical trials.
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Affiliation(s)
- Caroline L Benn
- Medical and Molecular Genetics, King's College London School of Medicine, 8th Floor Tower Wing, Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
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Dai W, Teodoridis JM, Graham J, Zeller C, Huang THM, Yan P, Vass JK, Brown R, Paul J. Methylation Linear Discriminant Analysis (MLDA) for identifying differentially methylated CpG islands. BMC Bioinformatics 2008; 9:337. [PMID: 18691414 PMCID: PMC2529322 DOI: 10.1186/1471-2105-9-337] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Accepted: 08/08/2008] [Indexed: 01/09/2023] Open
Abstract
Background Hypermethylation of promoter CpG islands is strongly correlated to transcriptional gene silencing and epigenetic maintenance of the silenced state. As well as its role in tumor development, CpG island methylation contributes to the acquisition of resistance to chemotherapy. Differential Methylation Hybridisation (DMH) is one technique used for genome-wide DNA methylation analysis. The study of such microarray data sets should ideally account for the specific biological features of DNA methylation and the non-symmetrical distribution of the ratios of unmethylated and methylated sequences hybridised on the array. We have therefore developed a novel algorithm tailored to this type of data, Methylation Linear Discriminant Analysis (MLDA). Results MLDA was programmed in R (version 2.7.0) and the package is available at CRAN [1]. This approach utilizes linear regression models of non-normalised hybridisation data to define methylation status. Log-transformed signal intensities of unmethylated controls on the microarray are used as a reference. The signal intensities of DNA samples digested with methylation sensitive restriction enzymes and mock digested are then transformed to the likelihood of a locus being methylated using this reference. We tested the ability of MLDA to identify loci differentially methylated as analysed by DMH between cisplatin sensitive and resistant ovarian cancer cell lines. MLDA identified 115 differentially methylated loci and 23 out of 26 of these loci have been independently validated by Methylation Specific PCR and/or bisulphite pyrosequencing. Conclusion MLDA has advantages for analyzing methylation data from CpG island microarrays, since there is a clear rational for the definition of methylation status, it uses DMH data without between-group normalisation and is less influenced by cross-hybridisation of loci. The MLDA algorithm successfully identified differentially methylated loci between two classes of samples analysed by DMH using CpG island microarrays.
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Affiliation(s)
- Wei Dai
- Ovarian Cancer Action Centre and Section of Epigenetics, Department of Oncology, Imperial College, Hammersmith Hospital, London, UK.
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Lee S, Hong S, Kang S. The ubiquitin-conjugating enzyme UbcH6 regulates the transcriptional repression activity of the SCA1 gene product ataxin-1. Biochem Biophys Res Commun 2008; 372:735-40. [PMID: 18519031 DOI: 10.1016/j.bbrc.2008.05.125] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Accepted: 05/20/2008] [Indexed: 11/17/2022]
Abstract
Spinocerebellar ataxia type 1 (SCA1) is an autosomal-dominant neurodegenerative disorder characterized by ataxia and progressive motor deterioration. SCA1 is caused by expansion of the polyglutamine tract in the SCA1 gene product, ataxin-1. We previously reported that the E2 ubiquitin-conjugating enzyme UbcH6 interacts with and ubiquitinates the ataxin-1 proteins as an E2-substrate cognate pair in the ubiquitin-proteasome system. In the present study, we further investigated whether the function of ataxin-1 is associated with UbcH6 and found that UbcH6 regulates the transcriptional repression activity of ataxin-1. The overexpression of UbcH6 reduced the transcriptional repression activity of ataxin-1. Interestingly, ataxin-1(30Q) was more affected by the presence of UbcH6 than ataxin-1(82Q), implying that the length of the polyglutamine tract in ataxin-1 might be involved in determining the stability of ataxin-1. The half-life of ataxin-1(82Q) was longer than that of ataxin-1(30Q) in the presence of UbcH6. shRNAs targeting UbcH6 enhanced the transcriptional repression activity of ataxin-1. In addition, the overexpression of UbcH6 reduced the formation of ataxin-1 aggregates. Our studies demonstrate that UbcH6 modulates the transcriptional repression activity of ataxin-1 by modulating the degradation of ataxin-1, suggesting that UbcH6 may have some therapeutic potential in the treatment of SCA1.
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Affiliation(s)
- Soyeon Lee
- Graduate School of Life Sciences and Biotechnology, Korea University, 1, 5ka, Anam-dong, Sungbuk-Ku, Seoul 136-701, Republic of Korea
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