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Stahl F, Evert BO, Han X, Breuer P, Wüllner U. Spinocerebellar Ataxia Type 3 Pathophysiology-Implications for Translational Research and Clinical Studies. Int J Mol Sci 2024; 25:3984. [PMID: 38612794 PMCID: PMC11012515 DOI: 10.3390/ijms25073984] [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: 02/14/2024] [Revised: 03/26/2024] [Accepted: 03/29/2024] [Indexed: 04/14/2024] Open
Abstract
The spinocerebellar ataxias (SCA) comprise a group of inherited neurodegenerative diseases. Machado-Joseph Disease (MJD) or spinocerebellar ataxia 3 (SCA3) is the most common autosomal dominant form, caused by the expansion of CAG repeats within the ataxin-3 (ATXN3) gene. This mutation results in the expression of an abnormal protein containing long polyglutamine (polyQ) stretches that confers a toxic gain of function and leads to misfolding and aggregation of ATXN3 in neurons. As a result of the neurodegenerative process, SCA3 patients are severely disabled and die prematurely. Several screening approaches, e.g., druggable genome-wide and drug library screenings have been performed, focussing on the reduction in stably overexpressed ATXN3(polyQ) protein and improvement in the resultant toxicity. Transgenic overexpression models of toxic ATXN3, however, missed potential modulators of endogenous ATXN3 regulation. In another approach to identify modifiers of endogenous ATXN3 expression using a CRISPR/Cas9-modified SK-N-SH wild-type cell line with a GFP-T2A-luciferase (LUC) cassette under the control of the endogenous ATXN3 promotor, four statins were identified as potential activators of expression. We here provide an overview of the high throughput screening approaches yet performed to find compounds or genomic modifiers of ATXN3(polyQ) toxicity in different SCA3 model organisms and cell lines to ameliorate and halt SCA3 progression in patients. Furthermore, the putative role of cholesterol in neurodegenerative diseases (NDDs) in general and SCA3 in particular is discussed.
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Affiliation(s)
- Fabian Stahl
- German Centre for Neurodegenerative Disease (DZNE), 53127 Bonn, Germany;
| | - Bernd O. Evert
- Departments of Neurology and Neurodegenerative Diseases, University of Bonn, 53127 Bonn, Germany; (B.O.E.); (X.H.); (P.B.)
| | - Xinyu Han
- Departments of Neurology and Neurodegenerative Diseases, University of Bonn, 53127 Bonn, Germany; (B.O.E.); (X.H.); (P.B.)
| | - Peter Breuer
- Departments of Neurology and Neurodegenerative Diseases, University of Bonn, 53127 Bonn, Germany; (B.O.E.); (X.H.); (P.B.)
| | - Ullrich Wüllner
- German Centre for Neurodegenerative Disease (DZNE), 53127 Bonn, Germany;
- Departments of Neurology and Neurodegenerative Diseases, University of Bonn, 53127 Bonn, Germany; (B.O.E.); (X.H.); (P.B.)
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2
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Potapenko A, Davidson JM, Lee A, Laird AS. The deubiquitinase function of ataxin-3 and its role in the pathogenesis of Machado-Joseph disease and other diseases. Biochem J 2024; 481:461-480. [PMID: 38497605 PMCID: PMC11088879 DOI: 10.1042/bcj20240017] [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: 01/18/2024] [Revised: 03/04/2024] [Accepted: 03/07/2024] [Indexed: 03/19/2024]
Abstract
Machado-Joseph disease (MJD) is a devastating and incurable neurodegenerative disease characterised by progressive ataxia, difficulty speaking and swallowing. Consequently, affected individuals ultimately become wheelchair dependent, require constant care, and face a shortened life expectancy. The monogenic cause of MJD is expansion of a trinucleotide (CAG) repeat region within the ATXN3 gene, which results in polyglutamine (polyQ) expansion within the resultant ataxin-3 protein. While it is well established that the ataxin-3 protein functions as a deubiquitinating (DUB) enzyme and is therefore critically involved in proteostasis, several unanswered questions remain regarding the impact of polyQ expansion in ataxin-3 on its DUB function. Here we review the current literature surrounding ataxin-3's DUB function, its DUB targets, and what is known regarding the impact of polyQ expansion on ataxin-3's DUB function. We also consider the potential neuroprotective effects of ataxin-3's DUB function, and the intersection of ataxin-3's role as a DUB enzyme and regulator of gene transcription. Ataxin-3 is the principal pathogenic protein in MJD and also appears to be involved in cancer. As aberrant deubiquitination has been linked to both neurodegeneration and cancer, a comprehensive understanding of ataxin-3's DUB function is important for elucidating potential therapeutic targets in these complex conditions. In this review, we aim to consolidate knowledge of ataxin-3 as a DUB and unveil areas for future research to aid therapeutic targeting of ataxin-3's DUB function for the treatment of MJD and other diseases.
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Affiliation(s)
- Anastasiya Potapenko
- Motor Neuron Disease Research Centre, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Jennilee M. Davidson
- Motor Neuron Disease Research Centre, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Albert Lee
- Motor Neuron Disease Research Centre, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Angela S. Laird
- Motor Neuron Disease Research Centre, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW 2109, Australia
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3
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Felício D, du Mérac TR, Amorim A, Martins S. Functional implications of paralog genes in polyglutamine spinocerebellar ataxias. Hum Genet 2023; 142:1651-1676. [PMID: 37845370 PMCID: PMC10676324 DOI: 10.1007/s00439-023-02607-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/22/2023] [Indexed: 10/18/2023]
Abstract
Polyglutamine (polyQ) spinocerebellar ataxias (SCAs) comprise a group of autosomal dominant neurodegenerative disorders caused by (CAG/CAA)n expansions. The elongated stretches of adjacent glutamines alter the conformation of the native proteins inducing neurotoxicity, and subsequent motor and neurological symptoms. Although the etiology and neuropathology of most polyQ SCAs have been extensively studied, only a limited selection of therapies is available. Previous studies on SCA1 demonstrated that ATXN1L, a human duplicated gene of the disease-associated ATXN1, alleviated neuropathology in mice models. Other SCA-associated genes have paralogs (i.e., copies at different chromosomal locations derived from duplication of the parental gene), but their functional relevance and potential role in disease pathogenesis remain unexplored. Here, we review the protein homology, expression pattern, and molecular functions of paralogs in seven polyQ dominant ataxias-SCA1, SCA2, MJD/SCA3, SCA6, SCA7, SCA17, and DRPLA. Besides ATXN1L, we highlight ATXN2L, ATXN3L, CACNA1B, ATXN7L1, ATXN7L2, TBPL2, and RERE as promising functional candidates to play a role in the neuropathology of the respective SCA, along with the parental gene. Although most of these duplicates lack the (CAG/CAA)n region, if functionally redundant, they may compensate for a partial loss-of-function or dysfunction of the wild-type genes in SCAs. We aim to draw attention to the hypothesis that paralogs of disease-associated genes may underlie the complex neuropathology of dominant ataxias and potentiate new therapeutic strategies.
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Affiliation(s)
- Daniela Felício
- Instituto de Investigação e Inovação em Saúde (i3S), 4200-135, Porto, Portugal
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), 4200-135, Porto, Portugal
- Instituto Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, 4050-313, Porto, Portugal
| | - Tanguy Rubat du Mérac
- Instituto de Investigação e Inovação em Saúde (i3S), 4200-135, Porto, Portugal
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), 4200-135, Porto, Portugal
- Faculty of Science, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - António Amorim
- Instituto de Investigação e Inovação em Saúde (i3S), 4200-135, Porto, Portugal
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), 4200-135, Porto, Portugal
- Department of Biology, Faculty of Sciences, University of Porto, 4169-007, Porto, Portugal
| | - Sandra Martins
- Instituto de Investigação e Inovação em Saúde (i3S), 4200-135, Porto, Portugal.
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), 4200-135, Porto, Portugal.
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Hernández‐Carralero E, Cabrera E, Rodríguez-Torres G, Hernández-Reyes Y, Singh A, Santa-María C, Fernández-Justel J, Janssens R, Marteijn J, Evert B, Mailand N, Gómez M, Ramadan K, Smits VJ, Freire R. ATXN3 controls DNA replication and transcription by regulating chromatin structure. Nucleic Acids Res 2023; 51:5396-5413. [PMID: 36971114 PMCID: PMC10287915 DOI: 10.1093/nar/gkad212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 02/10/2023] [Accepted: 03/14/2023] [Indexed: 11/18/2023] Open
Abstract
The deubiquitinating enzyme Ataxin-3 (ATXN3) contains a polyglutamine (PolyQ) region, the expansion of which causes spinocerebellar ataxia type-3 (SCA3). ATXN3 has multiple functions, such as regulating transcription or controlling genomic stability after DNA damage. Here we report the role of ATXN3 in chromatin organization during unperturbed conditions, in a catalytic-independent manner. The lack of ATXN3 leads to abnormalities in nuclear and nucleolar morphology, alters DNA replication timing and increases transcription. Additionally, indicators of more open chromatin, such as increased mobility of histone H1, changes in epigenetic marks and higher sensitivity to micrococcal nuclease digestion were detected in the absence of ATXN3. Interestingly, the effects observed in cells lacking ATXN3 are epistatic to the inhibition or lack of the histone deacetylase 3 (HDAC3), an interaction partner of ATXN3. The absence of ATXN3 decreases the recruitment of endogenous HDAC3 to the chromatin, as well as the HDAC3 nuclear/cytoplasm ratio after HDAC3 overexpression, suggesting that ATXN3 controls the subcellular localization of HDAC3. Importantly, the overexpression of a PolyQ-expanded version of ATXN3 behaves as a null mutant, altering DNA replication parameters, epigenetic marks and the subcellular distribution of HDAC3, giving new insights into the molecular basis of the disease.
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Affiliation(s)
- Esperanza Hernández‐Carralero
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Escuela de Doctorado y Estudios de Posgrado, Universidad de la Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Elisa Cabrera
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
| | - Gara Rodríguez-Torres
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Escuela de Doctorado y Estudios de Posgrado, Universidad de la Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Yeray Hernández-Reyes
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Escuela de Doctorado y Estudios de Posgrado, Universidad de la Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Abhay N Singh
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
| | - Cristina Santa-María
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Madrid, Spain
| | - José Miguel Fernández-Justel
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Madrid, Spain
| | - Roel C Janssens
- Department of Molecular Genetics, Oncode Institute, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Jurgen A Marteijn
- Department of Molecular Genetics, Oncode Institute, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Bernd O Evert
- Department of Neurology, University Hospital Bonn, Bonn, Germany
| | - Niels Mailand
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
- Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - María Gómez
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Madrid, Spain
| | - Kristijan Ramadan
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK
| | - Veronique A J Smits
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
- Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
| | - Raimundo Freire
- Unidad de Investigación, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
- Universidad Fernando Pessoa Canarias, Las Palmas de Gran Canaria, Spain
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5
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Ozhelvaci F, Steczkiewicz K. Identification and Classification of Papain-like Cysteine Proteinases. J Biol Chem 2023:104801. [PMID: 37164157 DOI: 10.1016/j.jbc.2023.104801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 04/11/2023] [Accepted: 05/05/2023] [Indexed: 05/12/2023] Open
Abstract
Papain-like cysteine peptidases form a big and highly diverse superfamily of proteins involved in many important biological functions, such as protein turnover, deubiquitination, tissue remodeling, blood clotting, virulence, defense, and cell wall remodeling. High sequence and structure diversity observed within these proteins hinders their comprehensive classification as well as the identification of new representatives. Moreover, in general protein databases, many families already classified as papain-like lack details regarding their mechanism of action or biological function. Here, we use transitive remote homology searches and 3D modeling to newly classify 21 families to the papain-like cysteine peptidase superfamily. We attempt to predict their biological function, and provide structural chacterization of 89 protein clusters defined based on sequence similarity altogether spanning 106 papain-like families. Moreover, we systematically discuss observed diversity in sequences, structures, and catalytic sites. Eventually, we expand the list of human papain-related proteins by seven representatives, including dopamine receptor-interacting protein (DRIP1) as potential deubiquitinase, and centriole duplication regulating CEP76 as retaining catalytically active peptidase-like domain. The presented results not only provide structure-based rationales to already existing peptidase databases but also may inspire further experimental research focused on peptidase-related biological processes.
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Affiliation(s)
- Fatih Ozhelvaci
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Kamil Steczkiewicz
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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Sousa e Silva R, Sousa AD, Vieira J, Vieira CP. The Josephin domain (JD) containing proteins are predicted to bind to the same interactors: Implications for spinocerebellar ataxia type 3 (SCA3) studies using Drosophila melanogaster mutants. Front Mol Neurosci 2023; 16:1140719. [PMID: 37008788 PMCID: PMC10050893 DOI: 10.3389/fnmol.2023.1140719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 02/21/2023] [Indexed: 03/17/2023] Open
Abstract
Spinocerebellar ataxia type 3, also known as Machado-Joseph disease (SCA3/ MJD), is the most frequent polyglutamine (polyQ) neurodegenerative disorder. It is caused by a pathogenic expansion of the polyQ tract, located at the C-terminal region of the protein encoded by the ATXN3 gene. This gene codes for a deubiquitinating enzyme (DUB) that belongs to a gene family, that in humans is composed by three more genes (ATXN3L, JOSD1, and JOSD2), that define two gene lineages (the ATXN3 and the Josephins). These proteins have in common the N-terminal catalytic domain (Josephin domain, JD), that in Josephins is the only domain present. In ATXN3 knock-out mouse and nematode models, the SCA3 neurodegeneration phenotype is not, however, reproduced, suggesting that in the genome of these species there are other genes that are able to compensate for the lack of ATXN3. Moreover, in mutant Drosophila melanogaster, where the only JD protein is coded by a Josephin-like gene, expression of the expanded human ATXN3 gene reproduces multiple aspects of the SCA3 phenotype, in contrast with the results of the expression of the wild type human form. In order to explain these findings, phylogenetic, as well as, protein–protein docking inferences are here performed. Here we show multiple losses of JD containing genes across the animal kingdom, suggesting partial functional redundancy of these genes. Accordingly, we predict that the JD is essential for binding with ataxin-3 and proteins of the Josephin lineages, and that D. melanogaster mutants are a good model of SCA3 despite the absence of a gene from the ATXN3 lineage. The molecular recognition regions of the ataxin-3 binding and those predicted for the Josephins are, however, different. We also report different binding regions between the two ataxin-3 forms (wild-type (wt) and expanded (exp)). The interactors that show an increase in the interaction strength with exp ataxin-3, are enriched in extrinsic components of mitochondrial outer membrane and endoplasmatic reticulum membrane. On the other hand, the group of interactors that show a decrease in the interaction strength with exp ataxin-3 is significantly enriched in extrinsic component of cytoplasm.
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7
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Cendelin J, Cvetanovic M, Gandelman M, Hirai H, Orr HT, Pulst SM, Strupp M, Tichanek F, Tuma J, Manto M. Consensus Paper: Strengths and Weaknesses of Animal Models of Spinocerebellar Ataxias and Their Clinical Implications. THE CEREBELLUM 2021; 21:452-481. [PMID: 34378174 DOI: 10.1007/s12311-021-01311-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/21/2021] [Indexed: 01/02/2023]
Abstract
Spinocerebellar ataxias (SCAs) represent a large group of hereditary degenerative diseases of the nervous system, in particular the cerebellum, and other systems that manifest with a variety of progressive motor, cognitive, and behavioral deficits with the leading symptom of cerebellar ataxia. SCAs often lead to severe impairments of the patient's functioning, quality of life, and life expectancy. For SCAs, there are no proven effective pharmacotherapies that improve the symptoms or substantially delay disease progress, i.e., disease-modifying therapies. To study SCA pathogenesis and potential therapies, animal models have been widely used and are an essential part of pre-clinical research. They mainly include mice, but also other vertebrates and invertebrates. Each animal model has its strengths and weaknesses arising from model animal species, type of genetic manipulation, and similarity to human diseases. The types of murine and non-murine models of SCAs, their contribution to the investigation of SCA pathogenesis, pathological phenotype, and therapeutic approaches including their advantages and disadvantages are reviewed in this paper. There is a consensus among the panel of experts that (1) animal models represent valuable tools to improve our understanding of SCAs and discover and assess novel therapies for this group of neurological disorders characterized by diverse mechanisms and differential degenerative progressions, (2) thorough phenotypic assessment of individual animal models is required for studies addressing therapeutic approaches, (3) comparative studies are needed to bring pre-clinical research closer to clinical trials, and (4) mouse models complement cellular and invertebrate models which remain limited in terms of clinical translation for complex neurological disorders such as SCAs.
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Affiliation(s)
- Jan Cendelin
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic. .,Laboratory of Neurodegenerative Disorders, Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic.
| | - Marija Cvetanovic
- Department of Neuroscience, Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Mandi Gandelman
- Department of Neurology, University of Utah, 175 North Medical Drive East, Salt Lake City, UT, 84132, USA
| | - Hirokazu Hirai
- Department of Neurophysiology and Neural Repair, Gunma University Graduate School of Medicine, 3-39-22, Gunma, 371-8511, Japan.,Viral Vector Core, Gunma University Initiative for Advanced Research (GIAR), Gunma, 371-8511, Japan
| | - Harry T Orr
- Department of Laboratory Medicine and Pathology, Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, 175 North Medical Drive East, Salt Lake City, UT, 84132, USA
| | - Michael Strupp
- Department of Neurology and German Center for Vertigo and Balance Disorders, Hospital of the Ludwig-Maximilians University, Munich, Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany
| | - Filip Tichanek
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic.,Laboratory of Neurodegenerative Disorders, Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic
| | - Jan Tuma
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic.,The Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, MC 7843, San Antonio, TX, 78229, USA
| | - Mario Manto
- Unité des Ataxies Cérébelleuses, Service de Neurologie, CHU-Charleroi, Charleroi, Belgium.,Service des Neurosciences, Université de Mons, UMons, Mons, Belgium
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8
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Simões AT, Carmona V, Duarte-Neves J, Cunha-Santos J, Pereira de Almeida L. Identification of the calpain-generated toxic fragment of ataxin-3 protein provides new avenues for therapy of Machado-Joseph disease| Spinocerebellar ataxia type 3. Neuropathol Appl Neurobiol 2021; 48:e12748. [PMID: 34273111 DOI: 10.1111/nan.12748] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 06/26/2021] [Accepted: 07/11/2021] [Indexed: 12/14/2022]
Abstract
AIMS Machado-Joseph disease (MJD) is the most frequent dominantly inherited cerebellar ataxia worldwide. Expansion of a CAG trinucleotide in the MJD1 gene translates into a polyglutamine tract within ataxin-3, which upon proteolysis may lead to MJD. The aim of this work was to understand the in vivo contribution of calpain proteases to the pathogenesis of MJD. Therefore, we investigated (a) the calpain cleavage sites in ataxin-3 protein, (b) the most toxic ataxin-3 fragment generated by calpain cleavage and (c) whether targeting calpain cleavage sites of mutant ataxin-3 could be a therapeutic strategy for MJD. METHODS We generated truncated and calpain-resistant constructs at the predicted cleavage sites of ataxin-3 using inverse PCR mutagenesis. Lentiviral vectors encoding these constructs were transduced in the adult mouse brain prior to western blot and immunohistochemical analysis 5 and 8 weeks later. RESULTS We identified the putative calpain cleavage sites for both wild-type and mutant ataxin-3 proteins. The mutation of these sites eliminated the formation of the toxic fragments, namely, the 26-kDa fragment, the major contributor for striatal degeneration. Nonetheless, reducing the formation of both the 26- and 34-kDa fragments was required to preclude the intranuclear localisation of ataxin-3. A neuroprotective effect was observed upon mutagenesis of calpain cleavage sites within mutant ataxin-3 protein. CONCLUSIONS These findings suggest that the calpain system should be considered a target for MJD therapy. The identified calpain cleavage sites will contribute to the design of targeted drugs and genome editing systems for those specific locations.
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Affiliation(s)
- Ana Teresa Simões
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,CIBB-Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
| | - Vítor Carmona
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,CIBB-Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
| | - Joana Duarte-Neves
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,CIBB-Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
| | - Janete Cunha-Santos
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,CIBB-Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal
| | - Luís Pereira de Almeida
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,CIBB-Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
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9
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Lee JH, Lin SY, Liu JW, Lin SZ, Harn HJ, Chiou TW. n-Butylidenephthalide Modulates Autophagy to Ameliorate Neuropathological Progress of Spinocerebellar Ataxia Type 3 through mTOR Pathway. Int J Mol Sci 2021; 22:6339. [PMID: 34199295 PMCID: PMC8231882 DOI: 10.3390/ijms22126339] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/09/2021] [Accepted: 06/11/2021] [Indexed: 02/07/2023] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3), a hereditary and lethal neurodegenerative disease, is attributed to the abnormal accumulation of undegradable polyglutamine (polyQ), which is encoded by mutated ataxin-3 gene (ATXN3). The toxic fragments processed from mutant ATXN3 can induce neuronal death, leading to the muscular incoordination of the human body. Some treatment strategies of SCA3 are preferentially focused on depleting the abnormal aggregates, which led to the discovery of small molecule n-butylidenephthalide (n-BP). n-BP-promoted autophagy protected the loss of Purkinje cell in the cerebellum that regulates the network associated with motor functions. We report that the n-BP treatment may be effective in treating SCA3 disease. n-BP treatment led to the depletion of mutant ATXN3 with the expanded polyQ chain and the toxic fragments resulting in increased metabolic activity and alleviated atrophy of SCA3 murine cerebellum. Furthermore, n-BP treated animal and HEK-293GFP-ATXN3-84Q cell models could consistently show the depletion of aggregates through mTOR inhibition. With its unique mechanism, the two autophagic inhibitors Bafilomycin A1 and wortmannin could halt the n-BP-induced elimination of aggregates. Collectively, n-BP shows promising results for the treatment of SCA3.
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Affiliation(s)
- Jui-Hao Lee
- Everfront Biotech Inc., New Taipei City 22180, Taiwan; (J.-H.L.); (S.-Y.L.); (J.-W.L.)
- Department of Life Science, Graduate Institute of Biotechnology, National Dong-Hwa University, Hualien 97447, Taiwan
| | - Si-Yin Lin
- Everfront Biotech Inc., New Taipei City 22180, Taiwan; (J.-H.L.); (S.-Y.L.); (J.-W.L.)
- Department of Life Science, Graduate Institute of Biotechnology, National Dong-Hwa University, Hualien 97447, Taiwan
| | - Jen-Wei Liu
- Everfront Biotech Inc., New Taipei City 22180, Taiwan; (J.-H.L.); (S.-Y.L.); (J.-W.L.)
- Department of Life Science, Graduate Institute of Biotechnology, National Dong-Hwa University, Hualien 97447, Taiwan
| | - Shinn-Zong Lin
- Bioinnovation Center, Buddhist Tzu Chi Medical Foundation, Hualien 97002, Taiwan;
- Department of Neurosurgery, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Tzu Chi University, Hualien 97002, Taiwan
| | - Horng-Jyh Harn
- Bioinnovation Center, Buddhist Tzu Chi Medical Foundation, Hualien 97002, Taiwan;
- Department of Pathology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Tzu Chi University, Hualien 97002, Taiwan
| | - Tzyy-Wen Chiou
- Department of Life Science, Graduate Institute of Biotechnology, National Dong-Hwa University, Hualien 97447, Taiwan
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10
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Temussi PA, Tartaglia GG, Pastore A. The seesaw between normal function and protein aggregation: How functional interactions may increase protein solubility. Bioessays 2021; 43:e2100031. [PMID: 33783021 DOI: 10.1002/bies.202100031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 12/12/2022]
Abstract
Protein aggregation has been studied for at least 3 decades, and many of the principles that regulate this event are relatively well understood. Here, however, we present a different perspective to explain why proteins aggregate: we argue that aggregation may occur as a side-effect of the lack of one or more natural partners that, under physiologic conditions, would act as chaperones. This would explain why the same surfaces that have evolved for functional purposes are also those that favour aggregation. In the course of reviewing this field, we substantiate our hypothesis with three paradigmatic examples that argue for the generality of our proposal. An obvious corollary of this hypothesis is, of course, that targeting the physiological partners of a protein could be the most direct and specific approach to designing anti-aggregation molecules. Our analysis may thus inform a different strategy for combating diseases of protein aggregation and misfolding.
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Affiliation(s)
- Piero Andrea Temussi
- UK Dementia Research Institute at King's College London, The Maurice Wohl Institute, London, UK
| | - Gian Gaetano Tartaglia
- Center for Human Technologies, Central RNA laboratory, Istituto Italiano di Tecnologia, Genova, Italy
- Charles Darwin Department of Biology and Biotechnology, Sapienza University of Rome, Rome, Italy
| | - Annalisa Pastore
- UK Dementia Research Institute at King's College London, The Maurice Wohl Institute, London, UK
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11
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Current Status of Gene Therapy Research in Polyglutamine Spinocerebellar Ataxias. Int J Mol Sci 2021; 22:ijms22084249. [PMID: 33921915 PMCID: PMC8074016 DOI: 10.3390/ijms22084249] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 04/14/2021] [Accepted: 04/14/2021] [Indexed: 12/26/2022] Open
Abstract
Polyglutamine spinocerebellar ataxias (PolyQ SCAs) are a group of 6 rare autosomal dominant diseases, which arise from an abnormal CAG repeat expansion in the coding region of their causative gene. These neurodegenerative ataxic disorders are characterized by progressive cerebellar degeneration, which translates into progressive ataxia, the main clinical feature, often accompanied by oculomotor deficits and dysarthria. Currently, PolyQ SCAs treatment is limited only to symptomatic mitigation, and no therapy is available to stop or delay the disease progression, which culminates with death. Over the last years, many promising gene therapy approaches were investigated in preclinical studies and could lead to a future treatment to stop or delay the disease development. Here, we summed up the most promising of these therapies, categorizing them in gene augmentation therapy, gene silencing strategies, and gene edition approaches. While several of the reviewed strategies are promising, there is still a gap from the preclinical results obtained and their translation to clinical studies. However, there is an increase in the number of approved gene therapies, as well as a constant development in their safety and efficacy profiles. Thus, it is expected that in a near future some of the promising strategies reviewed here could be tested in a clinical setting and if successful provide hope for SCAs patients.
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12
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Kim T, Song B, Lee IS. Drosophila Glia: Models for Human Neurodevelopmental and Neurodegenerative Disorders. Int J Mol Sci 2020; 21:E4859. [PMID: 32660023 PMCID: PMC7402321 DOI: 10.3390/ijms21144859] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 06/27/2020] [Accepted: 07/07/2020] [Indexed: 12/12/2022] Open
Abstract
Glial cells are key players in the proper formation and maintenance of the nervous system, thus contributing to neuronal health and disease in humans. However, little is known about the molecular pathways that govern glia-neuron communications in the diseased brain. Drosophila provides a useful in vivo model to explore the conserved molecular details of glial cell biology and their contributions to brain function and disease susceptibility. Herein, we review recent studies that explore glial functions in normal neuronal development, along with Drosophila models that seek to identify the pathological implications of glial defects in the context of various central nervous system disorders.
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Affiliation(s)
| | | | - Im-Soon Lee
- Department of Biological Sciences, Center for CHANS, Konkuk University, Seoul 05029, Korea; (T.K.); (B.S.)
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13
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Herzog LK, Kevei É, Marchante R, Böttcher C, Bindesbøll C, Lystad AH, Pfeiffer A, Gierisch ME, Salomons FA, Simonsen A, Hoppe T, Dantuma NP. The Machado-Joseph disease deubiquitylase ataxin-3 interacts with LC3C/GABARAP and promotes autophagy. Aging Cell 2020; 19:e13051. [PMID: 31625269 PMCID: PMC6974715 DOI: 10.1111/acel.13051] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 09/16/2019] [Accepted: 09/23/2019] [Indexed: 12/21/2022] Open
Abstract
The pathology of spinocerebellar ataxia type 3, also known as Machado‐Joseph disease, is triggered by aggregation of toxic ataxin‐3 (ATXN3) variants containing expanded polyglutamine repeats. The physiological role of this deubiquitylase, however, remains largely unclear. Our recent work showed that ATX‐3, the nematode orthologue of ATXN3, together with the ubiquitin‐directed segregase CDC‐48, regulates longevity in Caenorhabditis elegans. Here, we demonstrate that the long‐lived cdc‐48.1; atx‐3 double mutant displays reduced viability under prolonged starvation conditions that can be attributed to the loss of catalytically active ATX‐3. Reducing the levels of the autophagy protein BEC‐1 sensitized worms to the effect of ATX‐3 deficiency, suggesting a role of ATX‐3 in autophagy. In support of this conclusion, the depletion of ATXN3 in human cells caused a reduction in autophagosomal degradation of proteins. Surprisingly, reduced degradation in ATXN3‐depleted cells coincided with an increase in the number of autophagosomes while levels of lipidated LC3 remained unaffected. We identified two conserved LIR domains in the catalytic Josephin domain of ATXN3 that directly interacted with the autophagy adaptors LC3C and GABARAP in vitro. While ATXN3 localized to early autophagosomes, it was not subject to lysosomal degradation, suggesting a transient regulatory interaction early in the autophagic pathway. We propose that the deubiquitylase ATX‐3/ATXN3 stimulates autophagic degradation by preventing superfluous initiation of autophagosomes, thereby promoting an efficient autophagic flux important to survive starvation.
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Affiliation(s)
- Laura K. Herzog
- Department of Cell and Molecular Biology Karolinska Institutet Stockholm Sweden
| | - Éva Kevei
- Institute for Genetics and CECAD Research Center University of Cologne Cologne Germany
| | - Ricardo Marchante
- Institute for Genetics and CECAD Research Center University of Cologne Cologne Germany
| | - Claudia Böttcher
- Department of Cell and Molecular Biology Karolinska Institutet Stockholm Sweden
| | - Christian Bindesbøll
- Department of Molecular Medicine Faculty of Medicine Institute of Basic Medical Sciences and Centre for Cancer Cell Reprogramming Institute of Clinical Medicine University of Oslo Oslo Norway
| | - Alf Håkon Lystad
- Department of Molecular Medicine Faculty of Medicine Institute of Basic Medical Sciences and Centre for Cancer Cell Reprogramming Institute of Clinical Medicine University of Oslo Oslo Norway
| | - Annika Pfeiffer
- Department of Cell and Molecular Biology Karolinska Institutet Stockholm Sweden
| | - Maria E. Gierisch
- Department of Cell and Molecular Biology Karolinska Institutet Stockholm Sweden
| | - Florian A. Salomons
- Department of Cell and Molecular Biology Karolinska Institutet Stockholm Sweden
| | - Anne Simonsen
- Department of Molecular Medicine Faculty of Medicine Institute of Basic Medical Sciences and Centre for Cancer Cell Reprogramming Institute of Clinical Medicine University of Oslo Oslo Norway
| | - Thorsten Hoppe
- Institute for Genetics and CECAD Research Center University of Cologne Cologne Germany
| | - Nico P. Dantuma
- Department of Cell and Molecular Biology Karolinska Institutet Stockholm Sweden
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14
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McLoughlin HS, Moore LR, Paulson HL. Pathogenesis of SCA3 and implications for other polyglutamine diseases. Neurobiol Dis 2019; 134:104635. [PMID: 31669734 DOI: 10.1016/j.nbd.2019.104635] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 09/30/2019] [Accepted: 10/03/2019] [Indexed: 12/14/2022] Open
Abstract
Tandem repeat diseases include the neurodegenerative disorders known as polyglutamine (polyQ) diseases, caused by CAG repeat expansions in the coding regions of the respective disease genes. The nine known polyQ disease include Huntington's disease (HD), dentatorubral-pallidoluysian atrophy (DRPLA), spinal bulbar muscular atrophy (SBMA), and six spinocerebellar ataxias (SCA1, SCA2, SCA3, SCA6, SCA7, and SCA17). The underlying disease mechanism in the polyQ diseases is thought principally to reflect dominant toxic properties of the disease proteins which, when harboring a polyQ expansion, differentially interact with protein partners and are prone to aggregate. Among the polyQ diseases, SCA3 is the most common SCA, and second to HD in prevalence worldwide. Here we summarize current understanding of SCA3 disease mechanisms within the broader context of the broader polyQ disease field. We emphasize properties of the disease protein, ATXN3, and new discoveries regarding three potential pathogenic mechanisms: 1) altered protein homeostasis; 2) DNA damage and dysfunctional DNA repair; and 3) nonneuronal contributions to disease. We conclude with an overview of the therapeutic implications of recent mechanistic insights.
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Affiliation(s)
| | - Lauren R Moore
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
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15
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Krauss S, Nalavade R, Weber S, Carter K, Evert BO. Upregulation of miR-25 and miR-181 Family Members Correlates with Reduced Expression of ATXN3 in Lymphocytes from SCA3 Patients. Microrna 2019; 8:76-85. [PMID: 30147021 DOI: 10.2174/2211536607666180821162403] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/03/2018] [Accepted: 08/20/2018] [Indexed: 01/06/2023]
Abstract
BACKGROUND Spinocerebellar ataxia type 3 (SCA3), the most common spinocerebellar ataxia, is caused by a polyglutamine (polyQ) expansion in the protein ataxin-3 (ATXN3). Silencing the expression of polyQ-expanded ATXN3 rescues the cellular disease phenotype. OBJECTIVE This study investigated the differential expression of microRNAs (miRNAs), small noncoding RNAs targeting gene expression, in lymphoblastoid cells (LCs) from SCA3 patients and the capability of identified deregulated miRNAs to target and alter ATXN3 expression. METHODS MiRNA profiling was performed by microarray hybridization of total RNA from control and SCA3-LCs. The capability of the identified miRNAs and their target sites to suppress ATXN3 expression was analyzed using mutagenesis, reverse transcription PCR, immunoblotting, luciferase reporter assays, mimics and precursors of the identified miRNAs. RESULTS SCA3-LCs showed significantly decreased expression levels of ATXN3 and a significant upregulation of the ATXN3-3'UTR targeting miRNAs, miR-32 and miR-181c and closely related members of the miR-25 and miR-181 family, respectively. MiR-32 and miR-181c effectively targeted the 3'UTR of ATXN3 and suppressed the expression of ATXN3. CONCLUSIONS The simultaneous upregulation of closely related miRNAs targeting the 3'UTR of ATXN3 and the significantly reduced ATXN3 expression levels in SCA3-LCs suggests that miR-25 and miR-181 family members cooperatively bind to the 3'UTR to suppress the expression of ATXN3. The findings further suggest that the upregulation of miR-25 and miR-181 family members in SCA3- LCs reflects a cell type-specific, protective mechanism to diminish polyQ-mediated cytotoxic effects. Thus, miRNA mimics of miR-25 and miR-181 family members may prove useful for the treatment of SCA3.
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Affiliation(s)
- Sybille Krauss
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Street 27, 53127 Bonn, Germany
| | - Rohit Nalavade
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Street 27, 53127 Bonn, Germany
| | - Stephanie Weber
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Street 27, 53127 Bonn, Germany
| | - Katlynn Carter
- Department of Neurology, University of Bonn, Sigmund-Freud-Street 25, 53127 Bonn, Germany
| | - Bernd O Evert
- Department of Neurology, University of Bonn, Sigmund-Freud-Street 25, 53127 Bonn, Germany
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16
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Krauss S, Evert BO. The Role of MicroRNAs in Spinocerebellar Ataxia Type 3. J Mol Biol 2019; 431:1729-1742. [PMID: 30664869 DOI: 10.1016/j.jmb.2019.01.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/05/2019] [Accepted: 01/11/2019] [Indexed: 02/07/2023]
Abstract
More than 90% of the human genome are transcribed as non-coding RNAs. While it is still under debate if all these non-coding transcripts are functional, there is emerging evidence that RNA has several important functions in addition to coding for proteins. For example, microRNAs (miRNAs) are important regulatory RNAs that control gene expression in various biological processes and human diseases. In spinocerebellar ataxia type 3 (SCA3), a devastating neurodegenerative disease, miRNAs are involved in the disease process at different levels, including the deregulation of components of the general miRNA biogenesis machinery, as well as in the cell type-specific control of the expression of the SCA3 disease protein and other SCA3 disease-relevant proteins. However, it remains difficult to predict whether these changes are a cause or a consequence of the neurodegenerative process in SCA3. Further studies using standardized procedures for the analysis of miRNA expression and larger sample numbers are required to enhance our understanding of the miRNA-mediated processes involved in SCA3 disease and may enable the development of miRNA-based therapeutics. In this review, we summarize the findings of independent studies highlighting both the disease-related and cytoprotective roles of miRNAs that have been implicated so far in the disease process of SCA3.
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Affiliation(s)
- Sybille Krauss
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Street 27, 53127 Bonn, Germany
| | - Bernd O Evert
- Department of Neurology, University of Bonn, Sigmund-Freud-Street 25, 53127 Bonn, Germany.
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17
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Weishäupl D, Schneider J, Peixoto Pinheiro B, Ruess C, Dold SM, von Zweydorf F, Gloeckner CJ, Schmidt J, Riess O, Schmidt T. Physiological and pathophysiological characteristics of ataxin-3 isoforms. J Biol Chem 2018; 294:644-661. [PMID: 30455355 DOI: 10.1074/jbc.ra118.005801] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/08/2018] [Indexed: 12/18/2022] Open
Abstract
Ataxin-3 is a deubiquitinating enzyme and the affected protein in the neurodegenerative disorder Machado-Joseph disease (MJD). The ATXN3 gene is alternatively spliced, resulting in protein isoforms that differ in the number of ubiquitin-interacting motifs. Additionally, nonsynonymous SNPs in ATXN3 cause amino acid changes in ataxin-3, and one of these polymorphisms introduces a premature stop codon in one isoform. Here, we examined the effects of different ataxin-3 isoforms and of the premature stop codon on ataxin-3's physiological function and on main disease mechanisms. At the physiological level, we show that alternative splicing and the premature stop codon alter ataxin-3 stability and that ataxin-3 isoforms differ in their enzymatic deubiquitination activity, subcellular distribution, and interaction with other proteins. At the pathological level, we found that the expansion of the polyglutamine repeat leads to a stabilization of ataxin-3 and that ataxin-3 isoforms differ in their aggregation properties. Interestingly, we observed a functional interaction between normal and polyglutamine-expanded ATXN3 allelic variants. We found that interactions between different ATXN3 allelic variants modify the physiological and pathophysiological properties of ataxin-3. Our findings indicate that alternative splicing and interactions between different ataxin-3 isoforms affect not only major aspects of ataxin-3 function but also MJD pathogenesis. Our results stress the importance of considering isoforms of disease-causing proteins and their interplay with the normal allelic variant as disease modifiers in MJD and autosomal-dominantly inherited diseases in general.
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Affiliation(s)
- Daniel Weishäupl
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany.,the Graduate Training Center of Neuroscience, 72074 Tübingen, Germany
| | - Juliane Schneider
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Barbara Peixoto Pinheiro
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Corinna Ruess
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Sandra Maria Dold
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Felix von Zweydorf
- the German Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany, and
| | - Christian Johannes Gloeckner
- the German Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany, and.,the Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, 72076 Tübingen, Germany
| | - Jana Schmidt
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Olaf Riess
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Thorsten Schmidt
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany, .,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
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18
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Matos CA, de Almeida LP, Nóbrega C. Machado-Joseph disease/spinocerebellar ataxia type 3: lessons from disease pathogenesis and clues into therapy. J Neurochem 2018; 148:8-28. [PMID: 29959858 DOI: 10.1111/jnc.14541] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 06/05/2018] [Accepted: 06/27/2018] [Indexed: 12/25/2022]
Abstract
Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is an incurable disorder, widely regarded as the most common form of spinocerebellar ataxia in the world. MJD/SCA3 arises from mutation of the ATXN3 gene, but this simple monogenic cause contrasts with the complexity of the pathogenic mechanisms that are currently admitted to underlie neuronal dysfunction and death. The aberrantly expanded protein product - ataxin-3 - is known to aggregate and generate toxic species that disrupt several cell systems, including autophagy, proteostasis, transcription, mitochondrial function and signalling. Over the years, research into putative therapeutic approaches has often been devoted to the development of strategies that counteract disease at different stages of cellular pathogenesis. Silencing the pathogenic protein, blocking aggregation, inhibiting toxic proteolytic processing and counteracting dysfunctions of the cellular systems affected have yielded promising ameliorating results in studies with cellular and animal models. The current review analyses the available studies dedicated to the investigation of MJD/SCA3 pathogenesis and the exploration of possible therapeutic strategies, focusing primarily on gene therapy and pharmacological approaches rooted on the molecular and cellular mechanisms of disease.
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Affiliation(s)
- Carlos A Matos
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Luís Pereira de Almeida
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal.,Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Clévio Nóbrega
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal.,Department of Biomedical Sciences and Medicine, University of Algarve, Coimbra, Portugal.,Centre for Biomedical Research (CBMR), University of Algarve, Coimbra, Portugal.,Algarve Biomedical Center (ABC), University of Algarve, Faro, Portugal
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19
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Loss of the Spinocerebellar Ataxia type 3 disease protein ATXN3 alters transcription of multiple signal transduction pathways. PLoS One 2018; 13:e0204438. [PMID: 30231063 PMCID: PMC6145529 DOI: 10.1371/journal.pone.0204438] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 09/09/2018] [Indexed: 12/31/2022] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3) is a dominantly inherited neurodegenerative disorder caused by a polyglutamine-encoding CAG repeat expansion in the ATXN3 gene which encodes the deubiquitinating enzyme, ATXN3. Several mechanisms have been proposed to explain the pathogenic role of mutant, polyQ-expanded ATXN3 in SCA3 including disease protein aggregation, impairment of ubiquitin-proteasomal degradation and transcriptional dysregulation. A better understanding of the normal functions of this protein may shed light on SCA3 disease pathogenesis. To assess the potential normal role of ATXN3 in regulating gene expression, we compared transcriptional profiles in WT versus Atxn3 null mouse embryonic fibroblasts. Differentially expressed genes in the absence of ATXN3 contribute to multiple signal transduction pathways, suggesting a status switch of signaling pathways including depressed Wnt and BMP4 pathways and elevated growth factor pathways such as Prolactin, TGF-β, and Ephrin pathways. The Eph receptor A3 (Efna3), a receptor protein-tyrosine kinase in the Ephrin pathway that is highly expressed in the nervous system, was the most differentially upregulated gene in Atxn3 null MEFs. This increased expression of Efna3 was recapitulated in Atxn3 knockout mouse brainstem, a selectively vulnerable brain region in SCA3. Overexpression of normal or expanded ATXN3 was sufficient to repress Efna3 expression, supporting a role for ATXN3 in regulating Ephrin signaling. We further show that, in the absence of ATXN3, Efna3 upregulation is associated with hyperacetylation of histones H3 and H4 at the Efna3 promoter, which in turn is induced by decreased levels of HDAC3 and NCoR in ATXN3 null cells. Together, these results reveal a normal role for ATXN3 in transcriptional regulation of multiple signaling pathways of potential relevance to disease processes in SCA3.
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20
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Lima M, Raposo M. Towards the Identification of Molecular Biomarkers of Spinocerebellar Ataxia Type 3 (SCA3)/Machado-Joseph Disease (MJD). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1049:309-319. [PMID: 29427111 DOI: 10.1007/978-3-319-71779-1_16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Whereas spinocerebellar ataxia type 3 (SCA3)/Machado-Joseph disease (MJD) remains an untreatable disorder, disease-modifying compounds have begun being tested in the context of clinical trials; their success is dependent on the sensitivity of the methods used to measure subtle therapeutic benefits. Thus, efforts are being made to propose a battery of potential outcome measures, including molecular biomarkers (MBs), which remain to be identified; MBs are particularly pertinent if SCA3 trials are expected to enroll preataxic subjects. Recently, promising candidate MBs of SCA3 have emerged from gene expression studies. In this chapter we provide a synthesis of the cross-sectional and pilot longitudinal studies of blood-based transcriptional biomarkers conducted so far. Other alterations with potential to track the progression of SCA3, such as those involving mitochondrial DNA (mtDNA) are also referred. It is expected that a set of molecular biomarkers can be identified; these will be used in complementarity with clinical and imaging markers to fully track SCA3, from its preataxic phase to the disease stage.
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Affiliation(s)
- Manuela Lima
- Departamento de Biologia, Faculdade de Ciências e Tecnologia, Universidade dos Açores, Ponta Delgada, Portugal. .,Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Porto, Portugal. .,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
| | - Mafalda Raposo
- Departamento de Biologia, Faculdade de Ciências e Tecnologia, Universidade dos Açores, Ponta Delgada, Portugal.,Instituto de Investigação e Inovação em Saúde (I3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
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21
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Kristensen LV, Oppermann FS, Rauen MJ, Fog K, Schmidt T, Schmidt J, Harmuth T, Hartmann-Petersen R, Thirstrup K. Mass spectrometry analyses of normal and polyglutamine expanded ataxin-3 reveal novel interaction partners involved in mitochondrial function. Neurochem Int 2018; 112:5-17. [DOI: 10.1016/j.neuint.2017.10.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Revised: 09/01/2017] [Accepted: 10/09/2017] [Indexed: 12/13/2022]
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22
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Molecular Mechanisms and Cellular Pathways Implicated in Machado-Joseph Disease Pathogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1049:349-367. [PMID: 29427113 DOI: 10.1007/978-3-319-71779-1_18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Machado-Joseph disease (MJD) is a dominantly inherited disorder originally described in people of Portuguese descent, and associated with the expansion of a CAG tract in the coding region of the causative gene MJD1/ATX3. The CAG repeats range from 10 to 51 in the normal population and from 55 to 87 in SCA3/MJD patients. MJD1 encodes ataxin-3, a protein whose physiological function has been linked to ubiquitin-mediated proteolysis. Despite the identification of the causative mutation, the pathogenic process leading to the neurodegeneration observed in the disease is not yet completely understood. In the past years, several studies identified different molecular mechanisms and cellular pathways as being impaired or deregulated in MJD. Autophagy, proteolysis or post-translational modifications, among other processes, were implicated in MJD pathogenesis. From these studies it was possible to identify new targets for therapeutic intervention, which in some cases proved successful in models of disease.
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Fardghassemi Y, Tauffenberger A, Gosselin S, Parker JA. Rescue of ATXN3 neuronal toxicity in Caenorhabditiselegans by chemical modification of endoplasmic reticulum stress. Dis Model Mech 2017; 10:1465-1480. [PMID: 29061563 PMCID: PMC5769603 DOI: 10.1242/dmm.029736] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 10/08/2017] [Indexed: 12/13/2022] Open
Abstract
Polyglutamine expansion diseases are a group of hereditary neurodegenerative disorders that develop when a CAG repeat in the causative genes is unstably expanded above a certain threshold. The expansion of trinucleotide CAG repeats causes hereditary adult-onset neurodegenerative disorders, such as Huntington's disease, dentatorubral–pallidoluysian atrophy, spinobulbar muscular atrophy and multiple forms of spinocerebellar ataxia (SCA). The most common dominantly inherited SCA is the type 3 (SCA3), also known as Machado–Joseph disease (MJD), which is an autosomal dominant, progressive neurological disorder. The gene causatively associated with MJD is ATXN3. Recent studies have shown that this gene modulates endoplasmic reticulum (ER) stress. We generated transgenic Caenorhabditiselegans strains expressing human ATXN3 genes in motoneurons, and animals expressing mutant ATXN3-CAG89 alleles showed decreased lifespan, impaired movement, and rates of neurodegeneration greater than wild-type ATXN3-CAG10 controls. We tested three neuroprotective compounds (Methylene Blue, guanabenz and salubrinal) believed to modulate ER stress and observed that these molecules rescued ATXN3-CAG89 phenotypes. Furthermore, these compounds required specific branches of the ER unfolded protein response (UPRER), reduced global ER and oxidative stress, and polyglutamine aggregation. We introduce new C. elegans models for MJD based on the expression of full-length ATXN3 in a limited number of neurons. Using these models, we discovered that chemical modulation of the UPRER reduced neurodegeneration and warrants investigation in mammalian models of MJD. Summary: We introduce a novel C. elegans model for Machado–Joseph disease for use in preclinical drug discovery and identified guanabenz as a potent neuroprotective molecule.
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Affiliation(s)
- Yasmin Fardghassemi
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM) Montréal, Québec H2X 0A9, Canada.,Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Arnaud Tauffenberger
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM) Montréal, Québec H2X 0A9, Canada.,Département de pathologie et biologie cellulaire, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Sarah Gosselin
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM) Montréal, Québec H2X 0A9, Canada.,Département de neurosciences, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - J Alex Parker
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM) Montréal, Québec H2X 0A9, Canada .,Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, Québec H3T 1J4, Canada.,Département de pathologie et biologie cellulaire, Université de Montréal, Montréal, Québec H3T 1J4, Canada.,Département de neurosciences, Université de Montréal, Montréal, Québec H3T 1J4, Canada
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24
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Wang Z. Experimental and Clinical Strategies for Treating Spinocerebellar Ataxia Type 3. Neuroscience 2017; 371:138-154. [PMID: 29229556 DOI: 10.1016/j.neuroscience.2017.11.051] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/28/2017] [Accepted: 11/30/2017] [Indexed: 01/02/2023]
Abstract
Spinocerebellar ataxia type 3 (SCA3), or Machado-Joseph disease (MJD), is an autosomal dominant neurodegenerative disorder caused by the expansion of a polyglutamine (polyQ) tract in the ataxin-3 protein. To date, there is no effective therapy available to prevent progression of this disease. However, clinical strategies for alleviating various symptoms are imperative to promote a better quality of life for SCA3/MJD patients. Furthermore, experimental therapeutic strategies, including gene silencing or mutant protein clearance, mutant polyQ protein modification, stabilizing the native protein conformation, rescue of cellular dysfunction and neuromodulation to slow the progression of SCA3/MJD, have been developed. In this study, based on the current knowledge, I detail the clinical and experimental therapeutic strategies for treating SCA3/MJD, paying particular attention to drug discovery.
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Affiliation(s)
- Zijian Wang
- Genetic Engineering Laboratory, College of Biological and Environmental Engineering, Xi'an University, Xi'an, Shaanxi 710065, China.
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25
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Liu H, Li X, Ning G, Zhu S, Ma X, Liu X, Liu C, Huang M, Schmitt I, Wüllner U, Niu Y, Guo C, Wang Q, Tang TS. The Machado-Joseph Disease Deubiquitinase Ataxin-3 Regulates the Stability and Apoptotic Function of p53. PLoS Biol 2016; 14:e2000733. [PMID: 27851749 PMCID: PMC5112960 DOI: 10.1371/journal.pbio.2000733] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 10/18/2016] [Indexed: 11/18/2022] Open
Abstract
As a deubiquitinating enzyme (DUB), the physiological substrates of ataxin-3 (ATX-3) remain elusive, which limits our understanding of its normal cellular function and that of pathogenic mechanism of spinocerebellar ataxia type 3 (SCA3). Here, we identify p53 to be a novel substrate of ATX-3. ATX-3 binds to native and polyubiquitinated p53 and deubiquitinates and stabilizes p53 by repressing its degradation through the ubiquitin (Ub)-proteasome pathway. ATX-3 deletion destabilizes p53, resulting in deficiency of p53 activity and functions, whereas ectopic expression of ATX-3 induces selective transcription/expression of p53 target genes and promotes p53-dependent apoptosis in both mammalian cells and the central nervous system of zebrafish. Furthermore, the polyglutamine (polyQ)-expanded ATX-3 retains enhanced interaction and deubiquitination catalytic activity to p53 and causes more severe p53-dependent neurodegeneration in zebrafish brains and in the substantia nigra pars compacta (SNpc) or striatum of a transgenic SCA3 mouse model. Our findings identify a novel molecular link between ATX-3 and p53-mediated cell death and provide an explanation for the direct involvement of p53 in SCA3 disease pathogenesis. Ataxin-3 (ATX-3) is a ubiquitously expressed protein that mutated in a neurodegenerative disease called spinocerebellar ataxia type 3 (SCA3). It contains a polyglutamine (polyQ) tract near its C-terminus, the expansion of which is known to be the causative factor for SCA3. It has been known for a long time that ATX-3 is a deubiquitinating enzyme (DUB). However, the substrates targeted by ATX-3 in the physiological context remain elusive, thus largely limiting our understanding of its cellular function and that of the pathogenic mechanism of SCA3. This study has identified p53 to be a novel substrate of ATX-3, and its function is tightly regulated by ATX-3. PolyQ expansion augments ATX-3’s cellular function in p53 regulation. Due to enhanced interaction to p53 and up-regulation of p53, polyQ-expanded ATX-3 led to an increased p53-dependent neuronal cell death in zebrafish and mouse models, thus providing clear in vivo evidences for the direct involvement of p53 in SCA3 pathology. This study not only establishes a basic function of ATX-3 but also provides an explanation of how the interplays between ATX-3 and p53 contribute to the SCA3 pathogenesis; thus, it is an important contribution for the future development of therapeutic approaches for this currently untreatable neurodegenerative disease.
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Affiliation(s)
- Hongmei Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Xiaoling Li
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Guozhu Ning
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Shu Zhu
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Xiaolu Ma
- CAS Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Xiuli Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Chunying Liu
- Department of Pathology and Center for Experimental Animal Research, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College (PUMC), Beijing, China
| | - Min Huang
- CAS Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Ina Schmitt
- University of Bonn, Department of Neurology and German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Ullrich Wüllner
- University of Bonn, Department of Neurology and German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Yamei Niu
- Department of Pathology and Center for Experimental Animal Research, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College (PUMC), Beijing, China
| | - Caixia Guo
- CAS Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- * E-mail: (CG); (QW); (TST)
| | - Qiang Wang
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- * E-mail: (CG); (QW); (TST)
| | - Tie-Shan Tang
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
- * E-mail: (CG); (QW); (TST)
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26
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Matos CA, Nóbrega C, Louros SR, Almeida B, Ferreiro E, Valero J, Pereira de Almeida L, Macedo-Ribeiro S, Carvalho AL. Ataxin-3 phosphorylation decreases neuronal defects in spinocerebellar ataxia type 3 models. J Cell Biol 2016; 212:465-80. [PMID: 26880203 PMCID: PMC4754714 DOI: 10.1083/jcb.201506025] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Ataxin-3, the protein involved in spinocerebellar ataxia type 3 or Machado-Joseph disease, causes dendritic and synapse loss in cultured neurons when expanded, and mutation of phosphorylation site S12 reduces aggregation, neuronal loss, and synapse loss. Different neurodegenerative diseases are caused by aberrant elongation of repeated glutamine sequences normally found in particular human proteins. Although the proteins involved are ubiquitously distributed in human tissues, toxicity targets only defined neuronal populations. Changes caused by an expanded polyglutamine protein are possibly influenced by endogenous cellular mechanisms, which may be harnessed to produce neuroprotection. Here, we show that ataxin-3, the protein involved in spinocerebellar ataxia type 3, also known as Machado-Joseph disease, causes dendritic and synapse loss in cultured neurons when expanded. We report that S12 of ataxin-3 is phosphorylated in neurons and that mutating this residue so as to mimic a constitutive phosphorylated state counters the neuromorphologic defects observed. In rats stereotaxically injected with expanded ataxin-3–encoding lentiviral vectors, mutation of serine 12 reduces aggregation, neuronal loss, and synapse loss. Our results suggest that S12 plays a role in the pathogenic pathways mediated by polyglutamine-expanded ataxin-3 and that phosphorylation of this residue protects against toxicity.
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Affiliation(s)
- Carlos A Matos
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Clévio Nóbrega
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Susana R Louros
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Bruno Almeida
- Instituto de Biologia Molecular e Celular and Instituto de Investigação e Inovação em Saúde, University of Porto, 4200-135 Porto, Portugal
| | - Elisabete Ferreiro
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal Institute for Interdisciplinary Research, University of Coimbra, 3030-789 Coimbra, Portugal
| | - Jorge Valero
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal Ikerbasque Basque Foundation for Science and Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, E-48170 Zamudio, Spain
| | - Luís Pereira de Almeida
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Sandra Macedo-Ribeiro
- Instituto de Biologia Molecular e Celular and Instituto de Investigação e Inovação em Saúde, University of Porto, 4200-135 Porto, Portugal
| | - Ana Luísa Carvalho
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3004-517 Coimbra, Portugal
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27
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Characterization of the conformational fluctuations in the Josephin domain of ataxin-3. Biophys J 2016; 107:2932-2940. [PMID: 25517158 PMCID: PMC4269769 DOI: 10.1016/j.bpj.2014.10.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 10/10/2014] [Accepted: 10/10/2014] [Indexed: 11/24/2022] Open
Abstract
As for a variety of other molecular recognition processes, conformational fluctuations play an important role in the cleavage of polyubiquitin chains by the Josephin domain of ataxin-3. The interaction between Josephin and ubiquitin appears to be mediated by the motions of α-helical hairpin that is unusual among deubiquitinating enzymes. Here, we characterized the conformational fluctuations of the helical hairpin by incorporating NMR measurements as replica-averaged restraints in molecular dynamics simulations, and by validating the results by small-angle x-ray scattering measurements. This approach allowed us to define the extent of the helical hairpin motions and suggest a role of such motions in the recognition of ubiquitin.
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28
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Nóbrega C, Carmo-Silva S, Albuquerque D, Vasconcelos-Ferreira A, Vijayakumar UG, Mendonça L, Hirai H, de Almeida LP. Re-establishing ataxin-2 downregulates translation of mutant ataxin-3 and alleviates Machado-Joseph disease. Brain 2015; 138:3537-54. [PMID: 26490332 DOI: 10.1093/brain/awv298] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 08/25/2015] [Indexed: 01/09/2023] Open
Abstract
Machado-Joseph disease is a progressive neurodegenerative disorder associated with the polyQ-expanded ataxin-3 (encoded by ATXN3), for which no therapy is available. With the aim of clarifying the mechanism of neurodegeneration, we hypothesized that the abnormally long polyQ tract would interact aberrantly with ataxin-2 (encoded by ATXN2), another polyQ protein whose function has recently been linked to translational regulation. Using patient's samples and cellular and animal's models we found that in Machado-Joseph disease: (i) ataxin-2 levels are reduced; and (ii) its subcellular localization is changed towards the nucleus. Restoring ataxin-2 levels by lentiviral-mediated overexpression: (i) reduced mutant ataxin-3 levels; and (ii) rescued behaviour defects and neuropathology in a transgenic mouse model of Machado-Joseph disease. Conversely (i) mutating the ataxin-2 motif that enables binding to its natural interactor and translation activator poly(A)-binding protein; or (ii) overexpressing poly(A)-binding protein, had opposite effects, increasing mutant ataxin-3 translation and aggregation. This work suggests that in Machado-Joseph disease, mutant ataxin-3 drives an abnormal reduction of ataxin-2 levels, which overactivates poly(A)-binding protein, increases translation of mutant ataxin-3 and other proteins and aggravates Machado-Joseph disease. Re-establishment of ataxin-2 levels reduces mutant ataxin-3 and alleviates Machado-Joseph disease pathogenesis opening a new avenue for therapeutic intervention in this and potentially other polyQ disorders.
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Affiliation(s)
- Clévio Nóbrega
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal
| | - Sara Carmo-Silva
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal 2 Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
| | - David Albuquerque
- 3 Faculty of Sciences and Technology, University of Coimbra, 3004- 517 Coimbra, Portugal
| | - Ana Vasconcelos-Ferreira
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal 2 Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Udaya-Geetha Vijayakumar
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal
| | - Liliana Mendonça
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal
| | - Hirokazu Hirai
- 4 Department of Neurophysiology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Luís Pereira de Almeida
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal 2 Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
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Raposo M, Bettencourt C, Maciel P, Gao F, Ramos A, Kazachkova N, Vasconcelos J, Kay T, Rodrigues AJ, Bettencourt B, Bruges-Armas J, Geschwind D, Coppola G, Lima M. Novel candidate blood-based transcriptional biomarkers of Machado-Joseph disease. Mov Disord 2015; 30:968-75. [PMID: 25914309 DOI: 10.1002/mds.26238] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/27/2015] [Accepted: 03/02/2015] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Machado-Joseph disease (or spinocerebellar ataxia type 3) is a late-onset polyglutamine neurodegenerative disorder caused by a mutation in the ATXN3 gene, which encodes for the ubiquitously expressed protein ataxin-3. Previous studies on cell and animal models have suggested that mutated ataxin-3 is involved in transcriptional dysregulation. Starting with a whole-transcriptome profiling of peripheral blood samples from patients and controls, we aimed to confirm abnormal expression profiles in Machado-Joseph disease and to identify promising up-regulated genes as potential candidate biomarkers of disease status. METHODS The Illumina Human V4-HT12 array was used to measure transcriptome-wide gene expression in peripheral blood samples from 12 patients and 12 controls. Technical validation and validation in an independent set of samples were performed by quantitative real-time polymerase chain reaction (PCR). RESULTS Based on the results from the microarray, twenty six genes, found to be up-regulated in patients, were selected for technical validation by quantitative real-time PCR (validation rate of 81% for the up-regulation trend). Fourteen of these were further tested in an independent set of 42 patients and 35 controls; 10 genes maintained the up-regulation trend (FCGR3B, CSR2RA, CLC, TNFSF14, SLA, P2RY13, FPR2, SELPLG, YIPF6, and GPR96); FCGR3B, P2RY13, and SELPLG were significantly up-regulated in patients when compared with controls. CONCLUSIONS Our findings support the hypothesis that mutated ataxin-3 is associated with transcription dysregulation, detectable in peripheral blood cells. Furthermore, this is the first report suggesting a pool of up-regulated genes in Machado-Joseph disease that may have the potential to be used for fine phenotyping of this disease. © 2015 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Mafalda Raposo
- Centre of Research in Natural Resources (CIRN), University of the Azores, Ponta Delgada, Portugal.,Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal
| | | | - Patrícia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Fuying Gao
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, Los Angeles CA, USA
| | - Amanda Ramos
- Centre of Research in Natural Resources (CIRN), University of the Azores, Ponta Delgada, Portugal.,Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal
| | - Nadiya Kazachkova
- Centre of Research in Natural Resources (CIRN), University of the Azores, Ponta Delgada, Portugal.,Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal
| | - João Vasconcelos
- Department of Neurology, Hospital do Divino Espírito Santo, Ponta Delgada, Portugal
| | - Teresa Kay
- Department of Clinical Genetics, Hospital of D. Estefania, Lisbon, Portugal
| | - Ana João Rodrigues
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Bruno Bettencourt
- Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal.,Hospital de Santo Espírito da Ilha Terceira, SEEBMO, Angra do Heroísmo, Portugal
| | - Jácome Bruges-Armas
- Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal.,Hospital de Santo Espírito da Ilha Terceira, SEEBMO, Angra do Heroísmo, Portugal
| | - Daniel Geschwind
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, Los Angeles CA, USA
| | - Giovanni Coppola
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, Los Angeles CA, USA
| | - Manuela Lima
- Centre of Research in Natural Resources (CIRN), University of the Azores, Ponta Delgada, Portugal.,Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal
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30
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Faggiano S, Menon RP, Kelly GP, Todi SV, Scaglione KM, Konarev PV, Svergun DI, Paulson HL, Pastore A. Allosteric regulation of deubiquitylase activity through ubiquitination. Front Mol Biosci 2015; 2:2. [PMID: 25988170 PMCID: PMC4428445 DOI: 10.3389/fmolb.2015.00002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 01/07/2015] [Indexed: 12/28/2022] Open
Abstract
Ataxin-3, the protein responsible for spinocerebellar ataxia type-3, is a cysteine protease that specifically cleaves poly-ubiquitin chains and participates in the ubiquitin proteasome pathway. The enzymatic activity resides in the N-terminal Josephin domain. An unusual feature of ataxin-3 is its low enzymatic activity especially for mono-ubiquitinated substrates and short ubiquitin chains. However, specific ubiquitination at lysine 117 in the Josephin domain activates ataxin-3 through an unknown mechanism. Here, we investigate the effects of K117 ubiquitination on the structure and enzymatic activity of the protein. We show that covalently linked ubiquitin rests on the Josephin domain, forming a compact globular moiety and occupying a ubiquitin binding site previously thought to be essential for substrate recognition. In doing so, ubiquitination enhances enzymatic activity by locking the enzyme in an activated state. Our results indicate that ubiquitin functions both as a substrate and as an allosteric regulatory factor. We provide a novel example in which a conformational switch controls the activity of an enzyme that mediates deubiquitination.
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Affiliation(s)
- Serena Faggiano
- National Institute for Medical Research, Medical Research Council London, UK
| | - Rajesh P Menon
- National Institute for Medical Research, Medical Research Council London, UK
| | - Geoff P Kelly
- Medical Research Council Biomedical NMR Centre, National Institute for Medical Research, Medical Research Council London, UK
| | - Sokol V Todi
- Department of Pharmacology and Department of Neurology, Wayne State University School of Medicine Detroit, MI, USA
| | - K Matthew Scaglione
- Department of Biochemistry and The Neuroscience Research Center, Medical College of Wisconsin Milwaukee, WI, USA
| | - Petr V Konarev
- European Molecular Biology Laboratory Hamburg, Germany ; Laboratory of Reflectometry and Small-Angle Scattering, Institute of Crystallography Russian Academy of Sciences Moscow, Russia
| | | | - Henry L Paulson
- Department of Neurology, University of Michigan Medical School Ann Arbor, MI, USA
| | - Annalisa Pastore
- Department of Clinical Neuroscience, King's College London London, UK
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31
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Caenorhabditis elegans Models to Study the Molecular Biology of Ataxias. Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00068-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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32
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Neves-Carvalho A, Logarinho E, Freitas A, Duarte-Silva S, Costa MDC, Silva-Fernandes A, Martins M, Serra SC, Lopes AT, Paulson HL, Heutink P, Relvas JB, Maciel P. Dominant negative effect of polyglutamine expansion perturbs normal function of ataxin-3 in neuronal cells. Hum Mol Genet 2014; 24:100-17. [PMID: 25143392 DOI: 10.1093/hmg/ddu422] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The physiological function of Ataxin-3 (ATXN3), a deubiquitylase (DUB) involved in Machado-Joseph Disease (MJD), remains elusive. In this study, we demonstrate that ATXN3 is required for neuronal differentiation and for normal cell morphology, cytoskeletal organization, proliferation and survival of SH-SY5Y and PC12 cells. This cellular phenotype is associated with increased proteasomal degradation of α5 integrin subunit (ITGA5) and reduced activation of integrin signalling and is rescued by ITGA5 overexpression. Interestingly, silencing of ATXN3, overexpression of mutant versions of ATXN3 lacking catalytic activity or bearing an expanded polyglutamine (polyQ) tract led to partially overlapping phenotypes. In vivo analysis showed that both Atxn3 knockout and MJD transgenic mice had decreased levels of ITGA5 in the brain. Furthermore, abnormal morphology and reduced branching were observed both in cultured neurons expressing shRNA for ATXN3 and in those obtained from MJD mice. Our results show that ATXN3 rescues ITGA5 from proteasomal degradation in neurons and that polyQ expansion causes a partial loss of this cellular function, resulting in reduced integrin signalling and neuronal cytoskeleton modifications, which may be contributing to neurodegeneration.
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Affiliation(s)
- Andreia Neves-Carvalho
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and
| | - Elsa Logarinho
- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
| | - Ana Freitas
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and
| | - Sara Duarte-Silva
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and
| | | | - Anabela Silva-Fernandes
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and
| | - Margarida Martins
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and
| | - Sofia Cravino Serra
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and
| | - André T Lopes
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA and
| | - Peter Heutink
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - João B Relvas
- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
| | - Patrícia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and
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Evers MM, Toonen LJA, van Roon-Mom WMC. Ataxin-3 protein and RNA toxicity in spinocerebellar ataxia type 3: current insights and emerging therapeutic strategies. Mol Neurobiol 2014; 49:1513-31. [PMID: 24293103 PMCID: PMC4012159 DOI: 10.1007/s12035-013-8596-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 11/14/2013] [Indexed: 01/10/2023]
Abstract
Ataxin-3 is a ubiquitously expressed deubiqutinating enzyme with important functions in the proteasomal protein degradation pathway and regulation of transcription. The C-terminus of the ataxin-3 protein contains a polyglutamine (PolyQ) region that, when mutationally expanded to over 52 glutamines, causes the neurodegenerative disease spinocerebellar ataxia 3 (SCA3). In spite of extensive research, the molecular mechanisms underlying the cellular toxicity resulting from mutant ataxin-3 remain elusive and no preventive treatment is currently available. It has become clear over the last decade that the hallmark intracellular ataxin-3 aggregates are likely not the main toxic entity in SCA3. Instead, the soluble PolyQ containing fragments arising from proteolytic cleavage of ataxin-3 by caspases and calpains are now regarded to be of greater influence in pathogenesis. In addition, recent evidence suggests potential involvement of a RNA toxicity component in SCA3 and other PolyQ expansion disorders, increasing the pathogenic complexity. Herein, we review the functioning of ataxin-3 and the involvement of known protein and RNA toxicity mechanisms of mutant ataxin-3 that have been discovered, as well as future opportunities for therapeutic intervention.
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Affiliation(s)
- Melvin M. Evers
- Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333ZA Leiden, The Netherlands
| | - Lodewijk J. A. Toonen
- Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333ZA Leiden, The Netherlands
| | - Willeke M. C. van Roon-Mom
- Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333ZA Leiden, The Netherlands
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The ubiquitin proteasome system in Caenorhabditis elegans and its regulation. Redox Biol 2014; 2:333-47. [PMID: 24563851 PMCID: PMC3926112 DOI: 10.1016/j.redox.2014.01.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 01/08/2014] [Accepted: 01/10/2014] [Indexed: 11/20/2022] Open
Abstract
Protein degradation constitutes a major cellular function that is responsible for maintenance of the normal cellular physiology either through the degradation of normal proteins or through the elimination of damaged proteins. The Ubiquitin–Proteasome System (UPS)1 is one of the main proteolytic systems that orchestrate protein degradation. Given that up- and down- regulation of the UPS system has been shown to occur in various normal (such as ageing) and pathological (such as neurodegenerative diseases) processes, the exogenous modulation of the UPS function and activity holds promise of (a) developing new therapeutic interventions against various diseases and (b) establishing strategies to maintain cellular homeostasis. Since the proteasome genes are evolutionarily conserved, their role can be dissected in simple model organisms, such as the nematode, Caenorhabditis elegans. In this review, we survey findings on the redox regulation of the UPS in C. elegans showing that the nematode is an instrumental tool in the identification of major players in the UPS pathway. Moreover, we specifically discuss UPS-related genes that have been modulated in the nematode and in human cells and have resulted in similar effects thus further exhibiting the value of this model in the study of the UPS. UPS is one of the main proteolytic systems that orchestrate protein degradation. Proteasome function can be dissected in Caenorhabditis elegans. Nematodes can be used in the identification of major players in the UPS pathway.
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Clague MJ, Barsukov I, Coulson JM, Liu H, Rigden DJ, Urbé S. Deubiquitylases from genes to organism. Physiol Rev 2013; 93:1289-315. [PMID: 23899565 DOI: 10.1152/physrev.00002.2013] [Citation(s) in RCA: 320] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Ubiquitylation is a major posttranslational modification that controls most complex aspects of cell physiology. It is reversed through the action of a large family of deubiquitylating enzymes (DUBs) that are emerging as attractive therapeutic targets for a number of disease conditions. Here, we provide a comprehensive analysis of the complement of human DUBs, indicating structural motifs, typical cellular copy numbers, and tissue expression profiles. We discuss the means by which specificity is achieved and how DUB activity may be regulated. Generically DUB catalytic activity may be used to 1) maintain free ubiquitin levels, 2) rescue proteins from ubiquitin-mediated degradation, and 3) control the dynamics of ubiquitin-mediated signaling events. Functional roles of individual DUBs from each of five subfamilies in specific cellular processes are highlighted with an emphasis on those linked to pathological conditions where the association is supported by whole organism models. We then specifically consider the role of DUBs associated with protein degradative machineries and the influence of specific DUBs upon expression of receptors and channels at the plasma membrane.
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Affiliation(s)
- Michael J Clague
- Cellular and Molecular Physiology, Institute of Translational Medicine, and Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom.
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Rodríguez-Lebrón E, Costa MDC, Costa MD, Luna-Cancalon K, Peron TM, Fischer S, Boudreau RL, Davidson BL, Paulson HL. Silencing mutant ATXN3 expression resolves molecular phenotypes in SCA3 transgenic mice. Mol Ther 2013; 21:1909-18. [PMID: 23820820 DOI: 10.1038/mt.2013.152] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 06/17/2013] [Indexed: 12/18/2022] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3) is a neurodegenerative disease caused by a polyglutamine expansion in the deubiquitinating enzyme, Ataxin-3. Currently, there are no effective treatments for this fatal disorder but studies support the hypothesis that reducing mutant Ataxin-3 protein levels might reverse or halt the progression of disease in SCA3. Here, we sought to modulate ATXN3 expression in vivo using RNA interference. We developed artificial microRNA mimics targeting the 3'-untranslated region (3'UTR) of human ATXN3 and then used recombinant adeno-associated virus to deliver them to the cerebellum of transgenic mice expressing the full human disease gene (SCA3/MJD84.2 mice). Anti-ATXN3 microRNA mimics effectively suppressed human ATXN3 expression in SCA3/MJD84.2 mice. Short-term treatment cleared the abnormal nuclear accumulation of mutant Ataxin-3 throughout the transduced SCA3/MJD84.2 cerebellum. Analysis also revealed changes in the steady-state levels of specific microRNAs in the cerebellum of SCA3/MJD84.2 mice, a previously uncharacterized molecular phenotype of SCA3 that appears to be dependent on mutant Ataxin-3 expression. Our findings support the preclinical development of molecular therapies aimed at halting the expression of ATXN3 as a viable approach to SCA3 and point to microRNA deregulation as a potential surrogate marker of SCA3 pathogenesis.
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Almeida B, Fernandes S, Abreu IA, Macedo-Ribeiro S. Trinucleotide repeats: a structural perspective. Front Neurol 2013; 4:76. [PMID: 23801983 PMCID: PMC3687200 DOI: 10.3389/fneur.2013.00076] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/04/2013] [Indexed: 11/29/2022] Open
Abstract
Trinucleotide repeat (TNR) expansions are present in a wide range of genes involved in several neurological disorders, being directly involved in the molecular mechanisms underlying pathogenesis through modulation of gene expression and/or the function of the RNA or protein it encodes. Structural and functional information on the role of TNR sequences in RNA and protein is crucial to understand the effect of TNR expansions in neurodegeneration. Therefore, this review intends to provide to the reader a structural and functional view of TNR and encoded homopeptide expansions, with a particular emphasis on polyQ expansions and its role at inducing the self-assembly, aggregation and functional alterations of the carrier protein, which culminates in neuronal toxicity and cell death. Detail will be given to the Machado-Joseph Disease-causative and polyQ-containing protein, ataxin-3, providing clues for the impact of polyQ expansion and its flanking regions in the modulation of ataxin-3 molecular interactions, function, and aggregation.
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Affiliation(s)
- Bruno Almeida
- Instituto de Biologia Molecular e Celular, Universidade do Porto , Porto , Portugal
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Using C. elegans to Decipher the Cellular and Molecular Mechanisms Underlying Neurodevelopmental Disorders. Mol Neurobiol 2013; 48:465-89. [DOI: 10.1007/s12035-013-8434-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Accepted: 02/26/2013] [Indexed: 10/27/2022]
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Reina CP, Nabet BY, Young PD, Pittman RN. Basal and stress-induced Hsp70 are modulated by ataxin-3. Cell Stress Chaperones 2012; 17:729-42. [PMID: 22777893 PMCID: PMC3468683 DOI: 10.1007/s12192-012-0346-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 05/11/2012] [Accepted: 06/07/2012] [Indexed: 12/24/2022] Open
Abstract
Regulation of basal and induced levels of hsp70 is critical for cellular homeostasis. Ataxin-3 is a deubiquitinase with several cellular functions including transcriptional regulation and maintenance of protein homeostasis. While investigating potential roles of ataxin-3 in response to cellular stress, it appeared that ataxin-3 regulated hsp70. Basal levels of hsp70 were lower in ataxin-3 knockout (KO) mouse brain from 2 to 63 weeks of age and hsp70 was also lower in fibroblasts from ataxin-3 KO mice. Transfecting KO cells with ataxin-3 rescued basal levels of hsp70 protein. Western blots of representative chaperones including hsp110, hsp90, hsp70, hsc70, hsp60, hsp40/hdj2, and hsp25 indicated that only hsp70 was appreciably altered in KO fibroblasts and KO mouse brain. Turnover of hsp70 protein was similar in wild-type (WT) and KO cells; however, basal hsp70 promoter reporter activity was decreased in ataxin-3 KO cells. Transfecting ataxin-3 restored hsp70 basal promoter activity in KO fibroblasts to levels of promoter activity in WT cells; however, mutations that inactivated deubiquitinase activity or the ubiquitin interacting motifs did not restore full activity to hsp70 basal promoter activity. Hsp70 protein and promoter activity were higher in WT compared to KO cells exposed to heat shock and azetidine-2-carboxylic acid, but WT and KO cells had similar levels in response to cadmium. Heat shock factor-1 had decreased levels and increased turnover in ataxin-3 KO fibroblasts. Data in this study are consistent with ataxin-3 regulating basal level of hsp70 as well as modulating hsp70 in response to a subset of cellular stresses.
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Affiliation(s)
- Christopher P. Reina
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104 USA
- Present Address: Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ 08854 USA
| | - Barzin Y. Nabet
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104 USA
- Present Address: Department of Cancer Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104 USA
| | - Peter D. Young
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104 USA
| | - Randall N. Pittman
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104 USA
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Baptista MS, Duarte CB, Maciel P. Role of the ubiquitin-proteasome system in nervous system function and disease: using C. elegans as a dissecting tool. Cell Mol Life Sci 2012; 69:2691-715. [PMID: 22382927 PMCID: PMC11115168 DOI: 10.1007/s00018-012-0946-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 02/13/2012] [Accepted: 02/15/2012] [Indexed: 01/12/2023]
Abstract
In addition to its central roles in protein quality control, regulation of cell cycle, intracellular signaling, DNA damage response and transcription regulation, the ubiquitin-proteasome system (UPS) plays specific roles in the nervous system, where it contributes to precise connectivity through development, and later assures functionality by regulating a wide spectrum of neuron-specific cellular processes. Aberrations in this system have been implicated in the etiology of neurodevelopmental and neurodegenerative diseases. In this review, we provide an updated view on the UPS and highlight recent findings concerning its role in normal and diseased nervous systems. We discuss the advantages of the model organism Caenorhabditis elegans as a tool to unravel the major unsolved questions concerning this biochemical pathway and its involvement in nervous system function and dysfunction, and expose the new possibilities, using state-of-the-art techniques, to assess UPS function using this model system.
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Affiliation(s)
- Márcio S Baptista
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
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Costa MDC, Paulson HL. Toward understanding Machado-Joseph disease. Prog Neurobiol 2011; 97:239-57. [PMID: 22133674 DOI: 10.1016/j.pneurobio.2011.11.006] [Citation(s) in RCA: 198] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 11/10/2011] [Accepted: 11/14/2011] [Indexed: 12/16/2022]
Abstract
Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is the most common inherited spinocerebellar ataxia and one of many polyglutamine neurodegenerative diseases. In MJD, a CAG repeat expansion encodes an abnormally long polyglutamine (polyQ) tract in the disease protein, ATXN3. Here we review MJD, focusing primarily on the function and dysfunction of ATXN3 and on advances toward potential therapies. ATXN3 is a deubiquitinating enzyme (DUB) whose highly specialized properties suggest that it participates in ubiquitin-dependent proteostasis. By virtue of its interactions with VCP, various ubiquitin ligases and other ubiquitin-linked proteins, ATXN3 may help regulate the stability or activity of many proteins in diverse cellular pathways implicated in proteotoxic stress response, aging, and cell differentiation. Expansion of the polyQ tract in ATXN3 is thought to promote an altered conformation in the protein, leading to changes in interactions with native partners and to the formation of insoluble aggregates. The development of a wide range of cellular and animal models of MJD has been crucial to the emerging understanding of ATXN3 dysfunction upon polyQ expansion. Despite many advances, however, the principal molecular mechanisms by which mutant ATXN3 elicits neurotoxicity remain elusive. In a chronic degenerative disease like MJD, it is conceivable that mutant ATXN3 triggers multiple, interconnected pathogenic cascades that precipitate cellular dysfunction and eventual cell death. A better understanding of these complex molecular mechanisms will be important as scientists and clinicians begin to focus on developing effective therapies for this incurable, fatal disorder.
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Affiliation(s)
- Maria do Carmo Costa
- Department of Neurology, University of Michigan, A. Alfred Taubman Biomedical Sciences Research Building-BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109-2200, USA.
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Matos CA, de Macedo-Ribeiro S, Carvalho AL. Polyglutamine diseases: The special case of ataxin-3 and Machado–Joseph disease. Prog Neurobiol 2011; 95:26-48. [DOI: 10.1016/j.pneurobio.2011.06.007] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 06/06/2011] [Accepted: 06/07/2011] [Indexed: 10/18/2022]
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Bettencourt C, Lima M. Machado-Joseph Disease: from first descriptions to new perspectives. Orphanet J Rare Dis 2011; 6:35. [PMID: 21635785 PMCID: PMC3123549 DOI: 10.1186/1750-1172-6-35] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 06/02/2011] [Indexed: 11/23/2022] Open
Abstract
Machado-Joseph Disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), represents the most common form of SCA worldwide. MJD is an autosomal dominant neurodegenerative disorder of late onset, involving predominantly the cerebellar, pyramidal, extrapyramidal, motor neuron and oculomotor systems; although sharing features with other SCAs, the identification of minor, but more specific signs, facilitates its differential diagnosis. MJD presents strong phenotypic heterogeneity, which has justified the classification of patients into three main clinical types. Main pathological lesions are observed in the spinocerebellar system, as well as in the cerebellar dentate nucleus. MJD's causative mutation consists in an expansion of an unstable CAG tract in exon 10 of the ATXN3 gene, located at 14q32.1. Haplotype-based studies have suggested that two main founder mutations may explain the present global distribution of the disease; the ancestral haplotype is of Asian origin, and has an estimated age of around 5,800 years, while the second mutational event has occurred about 1,400 years ago. The ATXN3 gene encodes for ataxin-3, which is ubiquitously expressed in neuronal and non-neuronal tissues, and, among other functions, is thought to participate in cellular protein quality control pathways. Mutated ATXN3 alleles consensually present about 61 to 87 CAG repeats, resulting in an expanded polyglutamine tract in ataxin-3. This altered protein gains a neurotoxic function, through yet unclear mechanisms. Clinical variability of MJD is only partially explained by the size of the CAG tract, which leaves a residual variance that should be explained by still unknown additional factors. Several genetic tests are available for MJD, and Genetic Counseling Programs have been created to better assist the affected families, namely on what concerns the possibility of pre-symptomatic testing. The main goal of this review was to bring together updated knowledge on MJD, covering several aspects from its initial descriptions and clinical presentation, through the discovery of the causative mutation, its origin and dispersion, as well as molecular genetics aspects considered essential for a better understanding of its neuropathology. Issues related with molecular testing and Genetic Counseling, as well as recent progresses and perspectives on genetic therapy, are also addressed.
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Affiliation(s)
- Conceição Bettencourt
- Center of Research in Natural Resources (CIRN) and Department of Biology, University of the Azores, Ponta Delgada, Portugal
- Institute for Molecular and Cellular Biology (IBMC), University of Porto, Porto, Portugal
- Laboratorio de Biología Molecular, Instituto de Enfermedades Neurológicas de Guadalajara, Fundación Socio-Sanitaria de Castilla-La Mancha, Guadalajara, Spain
| | - Manuela Lima
- Center of Research in Natural Resources (CIRN) and Department of Biology, University of the Azores, Ponta Delgada, Portugal
- Institute for Molecular and Cellular Biology (IBMC), University of Porto, Porto, Portugal
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Teixeira-Castro A, Ailion M, Jalles A, Brignull HR, Vilaça JL, Dias N, Rodrigues P, Oliveira JF, Neves-Carvalho A, Morimoto RI, Maciel P. Neuron-specific proteotoxicity of mutant ataxin-3 in C. elegans: rescue by the DAF-16 and HSF-1 pathways. Hum Mol Genet 2011; 20:2996-3009. [PMID: 21546381 DOI: 10.1093/hmg/ddr203] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The risk of developing neurodegenerative diseases increases with age. Although many of the molecular pathways regulating proteotoxic stress and longevity are well characterized, their contribution to disease susceptibility remains unclear. In this study, we describe a new Caenorhabditis elegans model of Machado-Joseph disease pathogenesis. Pan-neuronal expression of mutant ATXN3 leads to a polyQ-length dependent, neuron subtype-specific aggregation and neuronal dysfunction. Analysis of different neurons revealed a pattern of dorsal nerve cord and sensory neuron susceptibility to mutant ataxin-3 that was distinct from the aggregation and toxicity profiles of polyQ-alone proteins. This reveals that the sequences flanking the polyQ-stretch in ATXN3 have a dominant influence on cell-intrinsic neuronal factors that modulate polyQ-mediated pathogenesis. Aging influences the ATXN3 phenotypes which can be suppressed by the downregulation of the insulin/insulin growth factor-1-like signaling pathway and activation of heat shock factor-1.
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Affiliation(s)
- Andreia Teixeira-Castro
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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Araujo J, Breuer P, Dieringer S, Krauss S, Dorn S, Zimmermann K, Pfeifer A, Klockgether T, Wuellner U, Evert BO. FOXO4-dependent upregulation of superoxide dismutase-2 in response to oxidative stress is impaired in spinocerebellar ataxia type 3. Hum Mol Genet 2011; 20:2928-41. [DOI: 10.1093/hmg/ddr197] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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Rodrigues AJ, Neves-Carvalho A, Teixeira-Castro A, Rokka A, Corthals G, Logarinho E, Maciel P. Absence of ataxin-3 leads to enhanced stress response in C. elegans. PLoS One 2011; 6:e18512. [PMID: 21526185 PMCID: PMC3079722 DOI: 10.1371/journal.pone.0018512] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 03/08/2011] [Indexed: 02/07/2023] Open
Abstract
Ataxin-3, the protein involved in Machado-Joseph disease, is able to bind ubiquitylated substrates and act as a deubiquitylating enzyme in vitro, and it has been involved in the modulation of protein degradation by the ubiquitin-proteasome pathway. C. elegans and mouse ataxin-3 knockout models are viable and without any obvious phenotype in a basal condition however their phenotype in stress situations has never been described. Considering the role of ataxin-3 in the protein degradation pathway, we analyzed the effects of heat shock, a known protein homeostasis stressor, in C. elegans ataxin-3 (ATX-3) knockout animals. We found that ATX-3 mutants have an exacerbated stress response and survive significantly better than wild type animals when subjected to a noxious heat shock stimulus. This increased thermotolerance of mutants was further enhanced by pre-exposure to a mild heat shock. At a molecular level, ATX-3 mutants have a distinct transcriptomic and proteomic profile with several molecular chaperones abnormally up-regulated during heat shock and recovery, consistent with the observed resistance phenotype. The improved thermotolerancein ATX-3 mutants is independent of heat shock factor 1, the maestro of the heat shock response, but fully dependent on DAF-16, a critical stress responsive transcription factor involved in longevity and stress resistance. We also show that the increased thermotolerance of ATX-3 mutants is mainly due to HSP-16.2, C12C8.1 and F44E5.5 given that the knockdown of these heat shock proteins using RNA interference causes the phenotype to revert. This report suggests that the absence of ATX-3 activates the DAF-16 pathway leading to an overexpression of molecular chaperones, which yields knockout animals with an improved capacity for dealing with deleterious stimuli.
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Affiliation(s)
- Ana João Rodrigues
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
| | - Andreia Neves-Carvalho
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
| | - Andreia Teixeira-Castro
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
| | - Anne Rokka
- Turku Centre for Biotechnology, University of Turku and Abo Akademi University, Turku, Finland
| | - Garry Corthals
- Turku Centre for Biotechnology, University of Turku and Abo Akademi University, Turku, Finland
| | - Elsa Logarinho
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Porto, Portugal
| | - Patrícia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- * E-mail:
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47
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Costa MDC, Bajanca F, Rodrigues AJ, Tomé RJ, Corthals G, Macedo-Ribeiro S, Paulson HL, Logarinho E, Maciel P. Ataxin-3 plays a role in mouse myogenic differentiation through regulation of integrin subunit levels. PLoS One 2010; 5:e11728. [PMID: 20668528 PMCID: PMC2909204 DOI: 10.1371/journal.pone.0011728] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 06/28/2010] [Indexed: 12/29/2022] Open
Abstract
Background During myogenesis several transcription factors and regulators of protein synthesis and assembly are rapidly degraded by the ubiquitin-proteasome system (UPS). Given the potential role of the deubiquitinating enzyme (DUB) ataxin-3 in the UPS, and the high expression of the murine ataxin-3 homolog in muscle during embryogenesis, we sought to define its role in muscle differentiation. Methodology/Principal Findings Using immunofluorescence analysis, we found murine ataxin-3 (mATX3) to be highly expressed in the differentiated myotome of E9.5 mouse embryos. C2C12 myoblasts depleted of mATX3 by RNA interference exhibited a round morphology, cell misalignment, and a delay in differentiation following myogenesis induction. Interestingly, these cells showed a down-regulation of α5 and α7 integrin subunit levels both by immunoblotting and immunofluorescence. Mouse ATX3 was found to interact with α5 integrin subunit and to stabilize this protein by repressing its degradation through the UPS. Proteomic analysis of mATX3-depleted C2C12 cells revealed alteration of the levels of several proteins related to integrin signaling. Conclusions Ataxin-3 is important for myogenesis through regulation of integrin subunit levels.
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Affiliation(s)
- Maria do Carmo Costa
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Fernanda Bajanca
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
| | - Ana-João Rodrigues
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
| | - Ricardo J. Tomé
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | | | - Sandra Macedo-Ribeiro
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Henry L. Paulson
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Elsa Logarinho
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Patrícia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- * E-mail:
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48
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Rodrigues AJ, do Carmo Costa M, Silva TL, Ferreira D, Bajanca F, Logarinho E, Maciel P. Absence of ataxin-3 leads to cytoskeletal disorganization and increased cell death. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:1154-63. [PMID: 20637808 DOI: 10.1016/j.bbamcr.2010.07.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 05/03/2010] [Accepted: 07/08/2010] [Indexed: 10/25/2022]
Abstract
Ataxin-3 (ATXN3) is a widely expressed protein that binds to ubiquitylated proteins, has deubiquitylating activity in vitro and is thought to modulate substrate degradation through the ubiquitin-proteasome pathway. Expansion of a polyglutamine tract in ATXN3 causes Machado-Joseph disease, a late-onset neurodegenerative disorder characterized by ubiquitin-positive aggregate formation and specific neuronal death. Although ATXN3 has been involved in transcriptional repression and in the ubiquitin-proteasome pathway, its biological function is still unknown. In this work, we show that depletion of ATXN3 using small-interference RNA (siRNA) causes a prominent phenotype in both human and mouse cell lines. A mild increase in ubiquitylation occurs and cells exhibit ubiquitin-positive foci, which is consistent with ATXN3 putative function as a deubiquitylating enzyme. In addition, siATXN3-silenced cells exhibit marked morphological changes such as rounder shape and loss of adhesion protrusions. At a structural level, the microtubule, microfilament and intermediate filament networks are severely compromised and disorganized. This cytoskeletal phenotype is reversible and dependent on ATXN3 levels. Cell-extracellular matrix connection is also affected in ATXN3-depleted cells as talin expression is reduced in the focal adhesions and lower levels of alpha-1 integrin subunit are expressed at their surface. Although the cytoskeletal and adhesion problems do not originate any major change in the cell cycle of siATXN3-depleted cells, cell death is increased in siATXN3 cultures compared to controls. In summary, in this work we show that the absence of ATXN3 leads to an overt cytoskeletal/adhesion defect raising the possibility that this protein may play a role in the cytoskeleton.
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Affiliation(s)
- Ana-João Rodrigues
- Life and Health Sciences Research Institute, University of Minho, Braga, Portugal
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49
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Hadwiger G, Dour S, Arur S, Fox P, Nonet ML. A monoclonal antibody toolkit for C. elegans. PLoS One 2010; 5:e10161. [PMID: 20405020 PMCID: PMC2854156 DOI: 10.1371/journal.pone.0010161] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 03/22/2010] [Indexed: 01/12/2023] Open
Abstract
Background Antibodies are critical tools in many avenues of biological research. Though antibodies can be produced in the research laboratory setting, most research labs working with vertebrates avail themselves of the wide array of commercially available reagents. By contrast, few such reagents are available for work with model organisms. Methodology/Principal Findings We report the production of monoclonal antibodies directed against a wide range of proteins that label specific subcellular and cellular components, and macromolecular complexes. Antibodies were made to synaptobrevin (SNB-1), a component of synaptic vesicles; to Rim (UNC-10), a protein localized to synaptic active zones; to transforming acidic coiled-coil protein (TAC-1), a component of centrosomes; to CENP-C (HCP-4), which in worms labels the entire length of their holocentric chromosomes; to ORC2 (ORC-2), a subunit of the DNA origin replication complex; to the nucleolar phosphoprotein NOPP140 (DAO-5); to the nuclear envelope protein lamin (LMN-1); to EHD1 (RME-1) a marker for recycling endosomes; to caveolin (CAV-1), a marker for caveolae; to the cytochrome P450 (CYP-33E1), a resident of the endoplasmic reticulum; to β-1,3-glucuronyltransferase (SQV-8) that labels the Golgi; to a chaperonin (HSP-60) targeted to mitochondria; to LAMP (LMP-1), a resident protein of lysosomes; to the alpha subunit of the 20S subcomplex (PAS-7) of the 26S proteasome; to dynamin (DYN-1) and to the α-subunit of the adaptor complex 2 (APA-2) as markers for sites of clathrin-mediated endocytosis; to the MAGUK, protein disks large (DLG-1) and cadherin (HMR-1), both of which label adherens junctions; to a cytoskeletal linker of the ezrin-radixin-moesin family (ERM-1), which localized to apical membranes; to an ERBIN family protein (LET-413) which localizes to the basolateral membrane of epithelial cells and to an adhesion molecule (SAX-7) which localizes to the plasma membrane at cell-cell contacts. In addition to working in whole mount immunocytochemistry, most of these antibodies work on western blots and thus should be of use for biochemical fractionation studies. Conclusions/Significance We have produced a set of monoclonal antibodies to subcellular components of the nematode C. elegans for the research community. These reagents are being made available through the Developmental Studies Hybridoma Bank (DSHB).
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Affiliation(s)
- Gayla Hadwiger
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Scott Dour
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Swathi Arur
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Paul Fox
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Michael L. Nonet
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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50
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Alves S, Nascimento-Ferreira I, Dufour N, Hassig R, Auregan G, Nóbrega C, Brouillet E, Hantraye P, Pedroso de Lima MC, Déglon N, de Almeida LP. Silencing ataxin-3 mitigates degeneration in a rat model of Machado-Joseph disease: no role for wild-type ataxin-3? Hum Mol Genet 2010; 19:2380-94. [PMID: 20308049 DOI: 10.1093/hmg/ddq111] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Machado-Joseph disease or spinocerebellar ataxia type 3 (MJD/SCA3) is a fatal, autosomal dominant disorder caused by a cytosine-adenine-guanine expansion in the coding region of the MJD1 gene. RNA interference has potential as a therapeutic approach but raises the issue of the role of wild-type ataxin-3 (WT ATX3) in MJD and of whether the expression of the wild-type protein must be maintained. To address this issue, we both overexpressed and silenced WT ATX3 in a rat model of MJD. We showed that (i) overexpression of WT ATX3 did not protect against MJD pathology, (ii) knockdown of WT ATX3 did not aggravate MJD pathology and that (iii) non-allele-specific silencing of ataxin-3 strongly reduced neuropathology in a rat model of MJD. Our findings indicate that therapeutic strategies involving non-allele-specific silencing to treat MJD patients may be safe and effective.
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Affiliation(s)
- Sandro Alves
- Center for Neurosciences & Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
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