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Costa RG, Conceição A, Matos CA, Nóbrega C. The polyglutamine protein ATXN2: from its molecular functions to its involvement in disease. Cell Death Dis 2024; 15:415. [PMID: 38877004 PMCID: PMC11178924 DOI: 10.1038/s41419-024-06812-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 06/04/2024] [Accepted: 06/05/2024] [Indexed: 06/16/2024]
Abstract
A CAG repeat sequence in the ATXN2 gene encodes a polyglutamine (polyQ) tract within the ataxin-2 (ATXN2) protein, showcasing a complex landscape of functions that have been progressively unveiled over recent decades. Despite significant progresses in the field, a comprehensive overview of the mechanisms governed by ATXN2 remains elusive. This multifaceted protein emerges as a key player in RNA metabolism, stress granules dynamics, endocytosis, calcium signaling, and the regulation of the circadian rhythm. The CAG overexpansion within the ATXN2 gene produces a protein with an extended poly(Q) tract, inducing consequential alterations in conformational dynamics which confer a toxic gain and/or partial loss of function. Although overexpanded ATXN2 is predominantly linked to spinocerebellar ataxia type 2 (SCA2), intermediate expansions are also implicated in amyotrophic lateral sclerosis (ALS) and parkinsonism. While the molecular intricacies await full elucidation, SCA2 presents ATXN2-associated pathological features, encompassing autophagy impairment, RNA-mediated toxicity, heightened oxidative stress, and disruption of calcium homeostasis. Presently, SCA2 remains incurable, with patients reliant on symptomatic and supportive treatments. In the pursuit of therapeutic solutions, various studies have explored avenues ranging from pharmacological drugs to advanced therapies, including cell or gene-based approaches. These endeavours aim to address the root causes or counteract distinct pathological features of SCA2. This review is intended to provide an updated compendium of ATXN2 functions, delineate the associated pathological mechanisms, and present current perspectives on the development of innovative therapeutic strategies.
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Affiliation(s)
- Rafael G Costa
- Algarve Biomedical Center Research Institute (ABC-RI), Faro, Portugal.
- PhD program in Biomedical Sciences, Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal.
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal.
| | - André Conceição
- Algarve Biomedical Center Research Institute (ABC-RI), Faro, Portugal
- PhD program in Biomedical Sciences, Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal
- Center for Neuroscience and Cell Biology (CNC), Coimbra, Portugal
- Champalimaud Research Program, Champalimaud Center for the Unknown, Lisbon, Portugal
| | - Carlos A Matos
- Algarve Biomedical Center Research Institute (ABC-RI), Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal
| | - Clévio Nóbrega
- Algarve Biomedical Center Research Institute (ABC-RI), Faro, Portugal.
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal.
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2
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Bonsor M, Ammar O, Schnoegl S, Wanker EE, Silva Ramos E. Polyglutamine disease proteins: Commonalities and differences in interaction profiles and pathological effects. Proteomics 2024; 24:e2300114. [PMID: 38615323 DOI: 10.1002/pmic.202300114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 03/25/2024] [Accepted: 03/27/2024] [Indexed: 04/16/2024]
Abstract
Currently, nine polyglutamine (polyQ) expansion diseases are known. They include spinocerebellar ataxias (SCA1, 2, 3, 6, 7, 17), spinal and bulbar muscular atrophy (SBMA), dentatorubral-pallidoluysian atrophy (DRPLA), and Huntington's disease (HD). At the root of these neurodegenerative diseases are trinucleotide repeat mutations in coding regions of different genes, which lead to the production of proteins with elongated polyQ tracts. While the causative proteins differ in structure and molecular mass, the expanded polyQ domains drive pathogenesis in all these diseases. PolyQ tracts mediate the association of proteins leading to the formation of protein complexes involved in gene expression regulation, RNA processing, membrane trafficking, and signal transduction. In this review, we discuss commonalities and differences among the nine polyQ proteins focusing on their structure and function as well as the pathological features of the respective diseases. We present insights from AlphaFold-predicted structural models and discuss the biological roles of polyQ-containing proteins. Lastly, we explore reported protein-protein interaction networks to highlight shared protein interactions and their potential relevance in disease development.
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Affiliation(s)
- Megan Bonsor
- Department of Neuroproteomics, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Orchid Ammar
- Department of Neuroproteomics, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Sigrid Schnoegl
- Department of Neuroproteomics, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Erich E Wanker
- Department of Neuroproteomics, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Eduardo Silva Ramos
- Department of Neuroproteomics, Max Delbrück Center for Molecular Medicine, Berlin, Germany
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3
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Chitre M, Emery P. ATXN2 is a target of N-terminal proteolysis. PLoS One 2023; 18:e0296085. [PMID: 38128014 PMCID: PMC10735043 DOI: 10.1371/journal.pone.0296085] [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: 10/11/2023] [Accepted: 12/04/2023] [Indexed: 12/23/2023] Open
Abstract
Spinocerebellar ataxia 2 (SCA2) is a neurodegenerative disorder caused by the expansion of the poly-glutamine (polyQ) tract of Ataxin-2 (ATXN2). Other polyQ-containing proteins such as ATXN7 and huntingtin are associated with the development of neurodegenerative diseases when their N-terminal polyQ domains are expanded. Furthermore, they undergo proteolytic processing events that produce N-terminal fragments that include the polyQ stretch, which are implicated in pathogenesis. Interestingly, N-terminal ATXN2 fragments were reported in a brain extract from a SCA2 patient, but it is currently unknown whether an expanded polyQ domain contributes to ATXN2 proteolytic susceptibility. Here, we used transient expression in HEK293 cells to determine whether ATXN2 is a target for specific N-terminal proteolysis. We found that ATXN2 proteins with either normal or expanded polyQ stretches undergo proteolytic cleavage releasing an N-terminal polyQ-containing fragment. We identified a short amino acid sequence downstream of the polyQ domain that is necessary for N-terminal cleavage of full-length ATXN2 and sufficient to induce proteolysis of a heterologous protein. However, this sequence is not required for cleavage of a short ATXN2 isoform produced from an alternative start codon located just upstream of the CAG repeats encoding the polyQ domain. Our study extends our understanding of ATXN2 posttranslational regulation by revealing that this protein can be the target of specific proteolytic cleavage events releasing polyQ-containing products that are modulated by the N-terminal domain of ATXN2. N-terminal ATXN2 proteolysis of expanded polyQ domains might contribute to SCA2 pathology, as observed in other neurodegenerative disorders caused by polyQ domain expansion.
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Affiliation(s)
- Monika Chitre
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Patrick Emery
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
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4
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Figueiredo F, Sárkány Z, Silva A, Vilasboas-Campos D, Maciel P, Teixeira-Castro A, Martins PM, Macedo-Ribeiro S. Drug repurposing of dopaminergic drugs to inhibit ataxin-3 aggregation. Biomed Pharmacother 2023; 165:115258. [PMID: 37549460 DOI: 10.1016/j.biopha.2023.115258] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/24/2023] [Accepted: 07/29/2023] [Indexed: 08/09/2023] Open
Abstract
The accumulation of mutant ataxin-3 (Atx3) in neuronal nuclear inclusions is a pathological hallmark of Machado-Joseph disease (MJD), also known as Spinocerebellar Ataxia Type 3. Decreasing the protein aggregation burden is a possible disease-modifying strategy to tackle MJD and other neurodegenerative disorders for which only symptomatic treatments are currently available. We performed a drug repurposing screening to identify inhibitors of Atx3 aggregation with known toxicological and pharmacokinetic profiles. Interestingly, dopamine hydrochloride and other catecholamines are among the most potent inhibitors of Atx3 aggregation in vitro. Our results indicate that low micromolar concentrations of dopamine markedly delay the formation of mature amyloid fibrils of mutant Atx3 through the inhibition of the earlier oligomerization steps. Although dopamine itself does not cross the blood-brain barrier, dopamine levels in the brain can be increased by low doses of dopamine precursors and dopamine agonists commonly used to treat Parkinsonian symptoms. In agreement, treatment with levodopa ameliorated motor symptoms in a C. elegans model of MJD. These findings suggest a possible application of dopaminergic drugs to halt or reduce Atx3 accumulation in the brains of MJD patients.
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Affiliation(s)
- Francisco Figueiredo
- 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; Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Zsuzsa Sárkány
- 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
| | - Alexandra Silva
- 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
| | - Daniela Vilasboas-Campos
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga, Guimarães, Portugal
| | - Patrícia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga, Guimarães, Portugal
| | - Andreia Teixeira-Castro
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga, Guimarães, Portugal
| | - Pedro M Martins
- 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.
| | - Sandra Macedo-Ribeiro
- 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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5
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Barbosa Pereira PJ, Manso JA, Macedo-Ribeiro S. The structural plasticity of polyglutamine repeats. Curr Opin Struct Biol 2023; 80:102607. [PMID: 37178477 DOI: 10.1016/j.sbi.2023.102607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/11/2023] [Accepted: 04/12/2023] [Indexed: 05/15/2023]
Abstract
From yeast to humans, polyglutamine (polyQ) repeat tracts are found frequently in the proteome and are particularly prominent in the activation domains of transcription factors. PolyQ is a polymorphic motif that modulates functional protein-protein interactions and aberrant self-assembly. Expansion of the polyQ repeated sequences beyond critical physiological repeat length thresholds triggers self-assembly and is linked to severe pathological implications. This review provides an overview of the current knowledge on the structures of polyQ tracts in the soluble and aggregated states and discusses the influence of neighboring regions on polyQ secondary structure, aggregation, and fibril morphologies. The influence of the genetic context of the polyQ-encoding trinucleotides is briefly discussed as a challenge for future endeavors in this field.
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Affiliation(s)
- Pedro José Barbosa Pereira
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal.
| | - José A Manso
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal
| | - Sandra Macedo-Ribeiro
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135, Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal
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6
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TR-FRET-Based Immunoassay to Measure Ataxin-2 as a Target Engagement Marker in Spinocerebellar Ataxia Type 2. Mol Neurobiol 2023; 60:3553-3567. [PMID: 36894829 PMCID: PMC10122633 DOI: 10.1007/s12035-023-03294-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 02/22/2023] [Indexed: 03/11/2023]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominantly inherited neurodegenerative disease, which belongs to the trinucleotide repeat disease group with a CAG repeat expansion in exon 1 of the ATXN2 gene resulting in an ataxin-2 protein with an expanded polyglutamine (polyQ)-stretch. The disease is late manifesting leading to early death. Today, therapeutic interventions to cure the disease or even to decelerate disease progression are not available yet. Furthermore, primary readout parameter for disease progression and therapeutic intervention studies are limited. Thus, there is an urgent need for quantifiable molecular biomarkers such as ataxin-2 becoming even more important due to numerous potential protein-lowering therapeutic intervention strategies. The aim of this study was to establish a sensitive technique to measure the amount of soluble polyQ-expanded ataxin-2 in human biofluids to evaluate ataxin-2 protein levels as prognostic and/or therapeutic biomarker in SCA2. Time-resolved fluorescence energy transfer (TR-FRET) was used to establish a polyQ-expanded ataxin-2-specific immunoassay. Two different ataxin-2 antibodies and two different polyQ-binding antibodies were validated in three different concentrations and tested in cellular and animal tissue as well as in human cell lines, comparing different buffer conditions to evaluate the best assay conditions. We established a TR-FRET-based immunoassay for soluble polyQ-expanded ataxin-2 and validated measurements in human cell lines including iPSC-derived cortical neurons. Additionally, our immunoassay was sensitive enough to monitor small ataxin-2 expression changes by siRNA or starvation treatment. We successfully established the first sensitive ataxin-2 immunoassay to measure specifically soluble polyQ-expanded ataxin-2 in human biomaterials.
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Egorova PA, Bezprozvanny IB. Electrophysiological Studies Support Utility of Positive Modulators of SK Channels for the Treatment of Spinocerebellar Ataxia Type 2. CEREBELLUM (LONDON, ENGLAND) 2022; 21:742-749. [PMID: 34978024 DOI: 10.1007/s12311-021-01349-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 06/14/2023]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an incurable hereditary disorder accompanied by cerebellar degeneration following ataxic symptoms. The causative gene for SCA2 is ATXN2. The ataxin-2 protein is involved in RNA metabolism; the polyQ expansion may interrupt ataxin-2 interaction with its molecular targets, thus representing a loss-of-function mutation. However, mutant ataxin-2 protein also displays the features of gain-of-function mutation since it forms the aggregates in SCA2 cells and also enhances the IP3-induced calcium release in affected neurons. The cerebellar Purkinje cells (PCs) are primarily affected in SCA2. Their tonic pacemaker activity is crucial for the proper cerebellar functioning. Disturbances in PC pacemaking are observed in many ataxic disorders. The abnormal intrinsic pacemaking was reported in mouse models of episodic ataxia type 2 (EA2), SCA1, SCA2, SCA3, SCA6, Huntington's disease (HD), and in some other murine models of the disorders associated with the cerebellar degeneration. In our studies using SCA2-58Q transgenic mice via cerebellar slice recording and in vivo recording from urethane-anesthetized mice and awake head-fixed mice, we have demonstrated the impaired firing frequency and irregularity of PCs in these mice. PC pacemaker activity is regulated by SK channels. The pharmacological activation of SK channels has demonstrated some promising results in the electrophysiological experiments on EA2, SCA1, SCA2, SCA3, SCA6, HD mice, and also on mutant CACNA1A mice. In our studies, we have reported that the SK activators CyPPA and NS309 converted bursting activity into tonic, while oral treatment with CyPPA and NS13001 significantly improved motor performance and PC morphology in SCA2 mice. The i.p. injections of chlorzoxazone (CHZ) during in vivo recording sessions converted bursting cells into tonic in anesthetized SCA2 mice. And, finally, long-term injections of CHZ recovered the precision of PC pacemaking activity in awake SCA2 mice and alleviated their motor decline. Thus, the SK activation can be used as a potential way to treat SCA2 and other diseases accompanied by cerebellar degeneration.
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Affiliation(s)
- Polina A Egorova
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia.
| | - Ilya B Bezprozvanny
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia.
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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8
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A Robust Assay to Monitor Ataxin-3 Amyloid Fibril Assembly. Cells 2022; 11:cells11121969. [PMID: 35741099 PMCID: PMC9222203 DOI: 10.3390/cells11121969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/14/2022] [Accepted: 06/16/2022] [Indexed: 02/05/2023] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3) is caused by the expansion of a glutamine repeat in the protein ataxin-3, which is deposited as intracellular aggregates in affected brain regions. Despite the controversial role of ataxin-3 amyloid structures in SCA3 pathology, the identification of molecules with the capacity to prevent aberrant self-assembly and stabilize functional conformation(s) of ataxin-3 is a key to the development of therapeutic solutions. Amyloid-specific kinetic assays are routinely used to measure rates of protein self-assembly in vitro and are employed during screening for fibrillation inhibitors. The high tendency of ataxin-3 to assemble into oligomeric structures implies that minor changes in experimental conditions can modify ataxin-3 amyloid assembly kinetics. Here, we determine the self-association rates of ataxin-3 and present a detailed study of the aggregation of normal and pathogenic ataxin-3, highlighting the experimental conditions that should be considered when implementing and validating ataxin-3 amyloid progress curves in different settings and in the presence of ataxin-3 interactors. This assay provides a unique and robust platform to screen for modulators of the first steps of ataxin-3 aggregation—a starting point for further studies with cell and animal models of SCA3.
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9
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Altered retinal structure and function in Spinocerebellar ataxia type 3. Neurobiol Dis 2022; 170:105774. [DOI: 10.1016/j.nbd.2022.105774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 01/13/2023] Open
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Huelsmeier J, Walker E, Bakthavachalu B, Ramaswami M. A C-terminal ataxin-2 disordered region promotes Huntingtin protein aggregation and neurodegeneration in Drosophila models of Huntington’s disease. G3 GENES|GENOMES|GENETICS 2021; 11:6385240. [PMID: 34718534 PMCID: PMC8664476 DOI: 10.1093/g3journal/jkab355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/01/2021] [Indexed: 11/15/2022]
Abstract
The Ataxin-2 (Atx2) protein contributes to the progression of neurodegenerative phenotypes in animal models of amyotrophic lateral sclerosis (ALS), type 2 spinocerebellar ataxia (SCA-2), Parkinson’s disease, and Huntington’s disease (HD). However, because the Atx2 protein contains multiple separable activities, deeper understanding requires experiments to address the exact mechanisms by which Atx2 modulates neurodegeneration (ND) progression. Recent work on two ALS models, C9ORF72 and FUS, in Drosophila has shown that a C-terminal intrinsically disordered region (cIDR) of Atx2 protein, required for assembly of ribonucleoprotein (RNP) granules, is essential for the progression of neurodegenerative phenotypes as well as for accumulation of protein inclusions associated with these ALS models. Here, we show that the Atx2-cIDR also similarly contributes to the progression of degenerative phenotypes and accumulation of Huntingtin protein aggregates in Drosophila models of HD. Because Huntingtin is not an established component of RNP granules, these observations support a recently hypothesized, unexpected protein-handling function for RNP granules, which could contribute to the progression of Huntington’s disease and, potentially, other proteinopathies.
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Affiliation(s)
- Joern Huelsmeier
- School of Genetics and Microbiology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Emily Walker
- School of Genetics and Microbiology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Baskar Bakthavachalu
- School of Basic Science, Indian Institute of Technology, Mandi, Suran 175075, India
| | - Mani Ramaswami
- School of Genetics and Microbiology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
- National Centre for Biological Sciences, TIFR, Bangalore 560065, India
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11
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Marcelo A, Afonso IT, Afonso-Reis R, Brito DVC, Costa RG, Rosa A, Alves-Cruzeiro J, Ferreira B, Henriques C, Nobre RJ, Matos CA, de Almeida LP, Nóbrega C. Autophagy in Spinocerebellar ataxia type 2, a dysregulated pathway, and a target for therapy. Cell Death Dis 2021; 12:1117. [PMID: 34845184 PMCID: PMC8630050 DOI: 10.1038/s41419-021-04404-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 11/08/2021] [Accepted: 11/15/2021] [Indexed: 01/18/2023]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an incurable and genetic neurodegenerative disorder. The disease is characterized by progressive degeneration of several brain regions, resulting in severe motor and non-motor clinical manifestations. The mutation causing SCA2 disease is an abnormal expansion of CAG trinucleotide repeats in the ATXN2 gene, leading to a toxic expanded polyglutamine segment in the translated ataxin-2 protein. While the genetic cause is well established, the exact mechanisms behind neuronal death induced by mutant ataxin-2 are not yet completely understood. Thus, the goal of this study is to investigate the role of autophagy in SCA2 pathogenesis and investigate its suitability as a target for therapeutic intervention. For that, we developed and characterized a new striatal lentiviral mouse model that resembled several neuropathological hallmarks observed in SCA2 disease, including formation of aggregates, neuronal marker loss, cell death and neuroinflammation. In this new model, we analyzed autophagic markers, which were also analyzed in a SCA2 cellular model and in human post-mortem brain samples. Our results showed altered levels of SQSTM1 and LC3B in cells and tissues expressing mutant ataxin-2. Moreover, an abnormal accumulation of these markers was detected in SCA2 patients' striatum and cerebellum. Importantly, the molecular activation of autophagy, using the compound cordycepin, mitigated the phenotypic alterations observed in disease models. Overall, our study suggests an important role for autophagy in the context of SCA2 pathology, proposing that targeting this pathway could be a potential target to treat SCA2 patients.
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Affiliation(s)
- Adriana Marcelo
- ABC-RI, Algarve Biomedical Center Research Institute, Algarve Biomedical Center, Faro, Portugal
- PhD Program in Biomedical Sciences, Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, Faro, Portugal
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal
- Faculty of Medicine and Biomedical Sciences, University of Algarve, Faro, Portugal
| | - Inês T Afonso
- ABC-RI, Algarve Biomedical Center Research Institute, Algarve Biomedical Center, Faro, Portugal
| | - Ricardo Afonso-Reis
- ABC-RI, Algarve Biomedical Center Research Institute, Algarve Biomedical Center, Faro, Portugal
- Faculty of Medicine and Biomedical Sciences, University of Algarve, Faro, Portugal
| | - David V C Brito
- ABC-RI, Algarve Biomedical Center Research Institute, Algarve Biomedical Center, Faro, Portugal
| | - Rafael G Costa
- ABC-RI, Algarve Biomedical Center Research Institute, Algarve Biomedical Center, Faro, Portugal
- Faculty of Medicine and Biomedical Sciences, University of Algarve, Faro, Portugal
| | - Ana Rosa
- ABC-RI, Algarve Biomedical Center Research Institute, Algarve Biomedical Center, Faro, Portugal
| | - João Alves-Cruzeiro
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal
| | - Benedita Ferreira
- ABC-RI, Algarve Biomedical Center Research Institute, Algarve Biomedical Center, Faro, Portugal
- Faculty of Medicine and Biomedical Sciences, University of Algarve, Faro, Portugal
| | - Carina Henriques
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal
| | - Rui J Nobre
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal
| | - Carlos A Matos
- ABC-RI, Algarve Biomedical Center Research Institute, Algarve Biomedical Center, Faro, Portugal
- Faculty of Medicine and Biomedical Sciences, University of Algarve, Faro, 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
- ABC-RI, Algarve Biomedical Center Research Institute, Algarve Biomedical Center, Faro, Portugal.
- Faculty of Medicine and Biomedical Sciences, University of Algarve, Faro, Portugal.
- Champalimaud Research Program, Champalimaud Center for the Unknown, Lisbon, Portugal.
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12
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Gerson JE, Safren N, Fischer S, Patel R, Crowley EV, Welday JP, Windle AK, Barmada S, Paulson HL, Sharkey LM. Ubiquilin-2 differentially regulates polyglutamine disease proteins. Hum Mol Genet 2021; 29:2596-2610. [PMID: 32681165 DOI: 10.1093/hmg/ddaa152] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 07/07/2020] [Accepted: 07/13/2020] [Indexed: 12/12/2022] Open
Abstract
Divergent protein context helps explain why polyglutamine expansion diseases differ clinically and pathologically. This heterogeneity may also extend to how polyglutamine disease proteins are handled by cellular pathways of proteostasis. Studies suggest, for example, that the ubiquitin-proteasome shuttle protein Ubiquilin-2 (UBQLN2) selectively interacts with specific polyglutamine disease proteins. Here we employ cellular models, primary neurons and mouse models to investigate the potential differential regulation by UBQLN2 of two polyglutamine disease proteins, huntingtin (HTT) and ataxin-3 (ATXN3). In cells, overexpressed UBQLN2 selectively lowered levels of full-length pathogenic HTT but not of HTT exon 1 fragment or full-length ATXN3. Consistent with these results, UBQLN2 specifically reduced accumulation of aggregated mutant HTT but not mutant ATXN3 in mouse models of Huntington's disease (HD) and spinocerebellar ataxia type 3 (SCA3), respectively. Normally a cytoplasmic protein, UBQLN2 translocated to the nuclei of neurons in HD mice but not in SCA3 mice. Remarkably, instead of reducing the accumulation of nuclear mutant ATXN3, UBQLN2 induced an accumulation of cytoplasmic ATXN3 aggregates in neurons of SCA3 mice. Together these results reveal a selective action of UBQLN2 toward polyglutamine disease proteins, indicating that polyglutamine expansion alone is insufficient to promote UBQLN2-mediated clearance of this class of disease proteins. Additional factors, including nuclear translocation of UBQLN2, may facilitate its action to clear intranuclear, aggregated disease proteins like HTT.
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Affiliation(s)
- Julia E Gerson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Nathaniel Safren
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Svetlana Fischer
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Ronak Patel
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Emily V Crowley
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Jacqueline P Welday
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Alexandra K Windle
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Sami Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Lisa M Sharkey
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
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13
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Raj K, Akundi RS. Mutant Ataxin-3-Containing Aggregates (MATAGGs) in Spinocerebellar Ataxia Type 3: Dynamics of the Disorder. Mol Neurobiol 2021; 58:3095-3118. [PMID: 33629274 DOI: 10.1007/s12035-021-02314-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 01/25/2021] [Indexed: 11/25/2022]
Abstract
Spinocerebellar ataxia type 3 (SCA3) is the most common type of SCA worldwide caused by abnormal polyglutamine expansion in the coding region of the ataxin-3 gene. Ataxin-3 is a multi-faceted protein involved in various cellular processes such as deubiquitination, cytoskeletal organisation, and transcriptional regulation. The presence of an expanded poly(Q) stretch leads to altered processing and misfolding of the protein culminating in the production of insoluble protein aggregates in the cell. Various post-translational modifications affect ataxin-3 fibrillation and aggregation. This review provides an exhaustive assessment of the various pathogenic mechanisms undertaken by the mutant ataxin-3-containing aggregates (MATAGGs) for disease induction and neurodegeneration. This includes in-depth discussion on MATAGG dynamics including their formation, role in neuronal pathogenesis, and the debate over the toxic v/s protective nature of the MATAGGs in disease progression. Additionally, the currently available therapeutic strategies against SCA3 have been reviewed. The shift in the focus of such strategies, from targeting the steps that lead to or reduce aggregate formation to targeting the expression of mutant ataxin-3 itself via RNA-based therapeutics, has also been presented. We also discuss the intriguing promise that various growth and neurotrophic factors, especially the insulin pathway, hold in the modulation of SCA3 progression. These emerging areas show the newer directions through which SCA3 can be targeted including various preclinical and clinical trials. All these advances made in the last three decades since the discovery of the ataxin-3 gene have been critically reviewed here.
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Affiliation(s)
- Kritika Raj
- Neuroinflammation Research Lab, Faculty of Life Sciences and Biotechnology, South Asian University, Chanakyapuri, New Delhi, 110021, India
| | - Ravi Shankar Akundi
- Neuroinflammation Research Lab, Faculty of Life Sciences and Biotechnology, South Asian University, Chanakyapuri, New Delhi, 110021, India.
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14
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Faber J, Schaprian T, Berkan K, Reetz K, França MC, de Rezende TJR, Hong J, Liao W, van de Warrenburg B, van Gaalen J, Durr A, Mochel F, Giunti P, Garcia-Moreno H, Schoels L, Hengel H, Synofzik M, Bender B, Oz G, Joers J, de Vries JJ, Kang JS, Timmann-Braun D, Jacobi H, Infante J, Joules R, Romanzetti S, Diedrichsen J, Schmid M, Wolz R, Klockgether T. Regional Brain and Spinal Cord Volume Loss in Spinocerebellar Ataxia Type 3. Mov Disord 2021; 36:2273-2281. [PMID: 33951232 PMCID: PMC9521507 DOI: 10.1002/mds.28610] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 03/17/2021] [Accepted: 03/18/2021] [Indexed: 01/22/2023] Open
Abstract
Background: Given that new therapeutic options for spinocerebellar ataxias are on the horizon, there is a need for markers that reflect disease-related alterations, in particular, in the preataxic stage, in which clinical scales are lacking sensitivity. Objective: The objective of this study was to quantify regional brain volumes and upper cervical spinal cord areas in spinocerebellar ataxia type 3 in vivo across the entire time course of the disease. Methods: We applied a brain segmentation approach that included a lobular subsegmentation of the cerebellum to magnetic resonance images of 210 ataxic and 48 preataxic spinocerebellar ataxia type 3 mutation carriers and 63 healthy controls. In addition, cervical cord cross-sectional areas were determined at 2 levels. Results: The metrics of cervical spinal cord segments C3 and C2, medulla oblongata, pons, and pallidum, and the cerebellar anterior lobe were reduced in preataxic mutation carriers compared with controls. Those of cervical spinal cord segments C2 and C3, medulla oblongata, pons, midbrain, cerebellar lobules crus II and X, cerebellar white matter, and pallidum were reduced in ataxic compared with nonataxic carriers. Of all metrics studied, pontine volume showed the steepest decline across the disease course. It covaried with ataxia severity, CAG repeat length, and age. The multivariate model derived from this analysis explained 46.33% of the variance of pontine volume. Conclusion: Regional brain and spinal cord tissue loss in spinocerebellar ataxia type 3 starts before ataxia onset. Pontine volume appears to be the most promising imaging biomarker candidate for interventional trials that aim at slowing the progression of spinocerebellar ataxia type 3.
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Affiliation(s)
- Jennifer Faber
- DZNE, German Center for Neurodegenerative Diseases, Bonn, Germany.,Department of Neurology, University Hospital Bonn, Bonn, Germany
| | - Tamara Schaprian
- DZNE, German Center for Neurodegenerative Diseases, Bonn, Germany
| | - Koyak Berkan
- DZNE, German Center for Neurodegenerative Diseases, Bonn, Germany
| | - Kathrin Reetz
- Department of Neurology, RWTH Aachen University, Bonn, Germany.,JARA-Brain Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich, Jülich, Germany
| | - Marcondes Cavalcante França
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, Brazil.,Department of Neurology, University of Campinas, Campinas, Brazil
| | - Thiago Junqueira Ribeiro de Rezende
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), Campinas, Brazil.,Department of Neurology, University of Campinas, Campinas, Brazil
| | - Jiang Hong
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Weihua Liao
- Department of Radiology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
| | - Bart van de Warrenburg
- Department of Neurology, Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Judith van Gaalen
- Department of Neurology, Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Alexandra Durr
- Sorbonne Université, Paris Brain Institute, AP-HP, INSERM, CNRS, Pitié-Salpêtrière University Hospital, Paris, France
| | - Fanny Mochel
- Sorbonne Université, Paris Brain Institute, AP-HP, INSERM, CNRS, Pitié-Salpêtrière University Hospital, Paris, France
| | - Paola Giunti
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London, United Kingdom.,National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Hector Garcia-Moreno
- Ataxia Centre, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London, United Kingdom.,National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Ludger Schoels
- Department of Neurodegenerative Diseases and Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,German Centre for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Holger Hengel
- Department of Neurodegenerative Diseases and Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,German Centre for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Matthis Synofzik
- Department of Neurodegenerative Diseases and Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,German Centre for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Benjamin Bender
- Department of Diagnostic and Interventional Neuroradiology, University Hospital Tübingen, Tübingen, Germany
| | - Gulin Oz
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA
| | - James Joers
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Jereon J de Vries
- Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Jun-Suk Kang
- Department of Neurology, Goethe University, Frankfurt am Main, Germany
| | | | - Heike Jacobi
- Department of Neurology, University Hospital of Heidelberg, Heidelberg, Germany
| | - Jon Infante
- Neurology Service, University Hospital Marques de Valdecilla-IDIVAL, University of Cantabria, Centro de Investigacion Biomedica en Red de Enfermedades Neurodegenerativas (CIBERNED), Santander, Spain
| | | | - Sandro Romanzetti
- JARA-Brain Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich, Jülich, Germany
| | - Jorn Diedrichsen
- Brain Mind Institute, Departmentof Computer Science, Department of Statistics, University of Western Ontario, London, Canada
| | - Matthias Schmid
- DZNE, German Center for Neurodegenerative Diseases, Bonn, Germany.,Institute of Medical Biometry, Informatics and Epidemiology, University Hospital Bonn, Bonn, Germany
| | | | - Thomas Klockgether
- DZNE, German Center for Neurodegenerative Diseases, Bonn, Germany.,Department of Neurology, University Hospital Bonn, Bonn, Germany
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15
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Canet-Pons J, Sen NE, Arsović A, Almaguer-Mederos LE, Halbach MV, Key J, Döring C, Kerksiek A, Picchiarelli G, Cassel R, René F, Dieterlé S, Fuchs NV, König R, Dupuis L, Lütjohann D, Gispert S, Auburger G. Atxn2-CAG100-KnockIn mouse spinal cord shows progressive TDP43 pathology associated with cholesterol biosynthesis suppression. Neurobiol Dis 2021; 152:105289. [PMID: 33577922 DOI: 10.1016/j.nbd.2021.105289] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/11/2020] [Accepted: 02/03/2021] [Indexed: 12/12/2022] Open
Abstract
Large polyglutamine expansions in Ataxin-2 (ATXN2) cause multi-system nervous atrophy in Spinocerebellar Ataxia type 2 (SCA2). Intermediate size expansions carry a risk for selective motor neuron degeneration, known as Amyotrophic Lateral Sclerosis (ALS). Conversely, the depletion of ATXN2 prevents disease progression in ALS. Although ATXN2 interacts directly with RNA, and in ALS pathogenesis there is a crucial role of RNA toxicity, the affected functional pathways remain ill defined. Here, we examined an authentic SCA2 mouse model with Atxn2-CAG100-KnockIn for a first definition of molecular mechanisms in spinal cord pathology. Neurophysiology of lower limbs detected sensory neuropathy rather than motor denervation. Triple immunofluorescence demonstrated cytosolic ATXN2 aggregates sequestrating TDP43 and TIA1 from the nucleus. In immunoblots, this was accompanied by elevated CASP3, RIPK1 and PQBP1 abundance. RT-qPCR showed increase of Grn, Tlr7 and Rnaset2 mRNA versus Eif5a2, Dcp2, Uhmk1 and Kif5a decrease. These SCA2 findings overlap well with known ALS features. Similar to other ataxias and dystonias, decreased mRNA levels for Unc80, Tacr1, Gnal, Ano3, Kcna2, Elovl5 and Cdr1 contrasted with Gpnmb increase. Preterminal stage tissue showed strongly activated microglia containing ATXN2 aggregates, with parallel astrogliosis. Global transcriptome profiles from stages of incipient motor deficit versus preterminal age identified molecules with progressive downregulation, where a cluster of cholesterol biosynthesis enzymes including Dhcr24, Msmo1, Idi1 and Hmgcs1 was prominent. Gas chromatography demonstrated a massive loss of crucial cholesterol precursor metabolites. Overall, the ATXN2 protein aggregation process affects diverse subcellular compartments, in particular stress granules, endoplasmic reticulum and receptor tyrosine kinase signaling. These findings identify new targets and potential biomarkers for neuroprotective therapies.
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Affiliation(s)
- Júlia Canet-Pons
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Nesli-Ece Sen
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany; Faculty of Biosciences, Goethe University, 60438 Frankfurt am Main, Germany
| | - Aleksandar Arsović
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Luis-Enrique Almaguer-Mederos
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany; Center for Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
| | - Melanie V Halbach
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Jana Key
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany; Faculty of Biosciences, Goethe University, 60438 Frankfurt am Main, Germany
| | - Claudia Döring
- Dr. Senckenberg Institute of Pathology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Anja Kerksiek
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, 53127 Bonn, Nordrhein-Westfalen, Germany
| | - Gina Picchiarelli
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Raphaelle Cassel
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Frédérique René
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Stéphane Dieterlé
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Nina V Fuchs
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225 Langen, Germany
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225 Langen, Germany
| | - Luc Dupuis
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Dieter Lütjohann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, 53127 Bonn, Nordrhein-Westfalen, Germany
| | - Suzana Gispert
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany.
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16
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A fine balance between Prpf19 and Exoc7 in achieving degradation of aggregated protein and suppression of cell death in spinocerebellar ataxia type 3. Cell Death Dis 2021; 12:136. [PMID: 33542212 PMCID: PMC7862454 DOI: 10.1038/s41419-021-03444-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 01/09/2021] [Accepted: 01/11/2021] [Indexed: 01/30/2023]
Abstract
Polyglutamine (polyQ) diseases comprise Huntington's disease and several subtypes of spinocerebellar ataxia, including spinocerebellar ataxia type 3 (SCA3). The genomic expansion of coding CAG trinucleotide sequence in disease genes leads to the production and accumulation of misfolded polyQ domain-containing disease proteins, which cause cellular dysfunction and neuronal death. As one of the principal cellular protein clearance pathways, the activity of the ubiquitin-proteasome system (UPS) is tightly regulated to ensure efficient clearance of damaged and toxic proteins. Emerging evidence demonstrates that UPS plays a crucial role in the pathogenesis of polyQ diseases. Ubiquitin (Ub) E3 ligases catalyze the transfer of a Ub tag to label proteins destined for proteasomal clearance. In this study, we identified an E3 ligase, pre-mRNA processing factor 19 (Prpf19/prp19), that modulates expanded ataxin-3 (ATXN3-polyQ), disease protein of SCA3, induced neurodegeneration in both mammalian and Drosophila disease models. We further showed that Prpf19/prp19 promotes poly-ubiquitination and degradation of mutant ATXN3-polyQ protein. Our data further demonstrated the nuclear localization of Prpf19/prp19 is essential for eliciting its modulatory function towards toxic ATXN3-polyQ protein. Intriguingly, we found that exocyst complex component 7 (Exoc7/exo70), a Prpf19/prp19 interacting partner, modulates expanded ATXN3-polyQ protein levels and toxicity in an opposite manner to Prpf19/prp19. Our data suggest that Exoc7/exo70 exerts its ATXN3-polyQ-modifying effect through regulating the E3 ligase function of Prpf19/prp19. In summary, this study allows us to better define the mechanistic role of Exoc7/exo70-regulated Prpf19/prp19-associated protein ubiquitination pathway in SCA3 pathogenesis.
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17
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Tejwani L, Lim J. Pathogenic mechanisms underlying spinocerebellar ataxia type 1. Cell Mol Life Sci 2020; 77:4015-4029. [PMID: 32306062 PMCID: PMC7541529 DOI: 10.1007/s00018-020-03520-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 03/06/2020] [Accepted: 04/06/2020] [Indexed: 02/06/2023]
Abstract
The family of hereditary cerebellar ataxias is a large group of disorders with heterogenous clinical manifestations and genetic etiologies. Among these, over 30 autosomal dominantly inherited subtypes have been identified, collectively referred to as the spinocerebellar ataxias (SCAs). Generally, the SCAs are characterized by a progressive gait impairment with classical cerebellar features, and in a subset of SCAs, accompanied by extra-cerebellar features. Beyond the common gait impairment and cerebellar atrophy, the wide range of additional clinical features observed across the SCAs is likely explained by the diverse set of mutated genes that encode proteins with seemingly disparate functional roles in nervous system biology. By synthesizing knowledge obtained from studies of the various SCAs over the past several decades, convergence onto a few key cellular changes, namely ion channel dysfunction and transcriptional dysregulation, has become apparent and may represent central mechanisms of cerebellar disease pathogenesis. This review will detail our current understanding of the molecular pathogenesis of the SCAs, focusing primarily on the first described autosomal dominant spinocerebellar ataxia, SCA1, as well as the emerging common core mechanisms across the various SCAs.
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Affiliation(s)
- Leon Tejwani
- Interdepartmental Neuroscience Program, Yale School of Medicine, 295 Congress Avenue, New Haven, CT, 06510, USA
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, 06510, USA
| | - Janghoo Lim
- Interdepartmental Neuroscience Program, Yale School of Medicine, 295 Congress Avenue, New Haven, CT, 06510, USA.
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, 06510, USA.
- Department of Genetics, Yale School of Medicine, New Haven, CT, 06510, USA.
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale School of Medicine, New Haven, CT, 06510, USA.
- Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, 06510, USA.
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18
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Arsović A, Halbach MV, Canet-Pons J, Esen-Sehir D, Döring C, Freudenberg F, Czechowska N, Seidel K, Baader SL, Gispert S, Sen NE, Auburger G. Mouse Ataxin-2 Expansion Downregulates CamKII and Other Calcium Signaling Factors, Impairing Granule-Purkinje Neuron Synaptic Strength. Int J Mol Sci 2020; 21:E6673. [PMID: 32932600 PMCID: PMC7555182 DOI: 10.3390/ijms21186673] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/07/2020] [Accepted: 09/10/2020] [Indexed: 12/13/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is caused by polyglutamine expansion in Ataxin-2 (ATXN2). This factor binds RNA/proteins to modify metabolism after stress, and to control calcium (Ca2+) homeostasis after stimuli. Cerebellar ataxias and corticospinal motor neuron degeneration are determined by gain/loss in ATXN2 function, so we aimed to identify key molecules in this atrophic process, as potential disease progression markers. Our Atxn2-CAG100-Knock-In mouse faithfully models features observed in patients at pre-onset, early and terminal stages. Here, its cerebellar global RNA profiling revealed downregulation of signaling cascades to precede motor deficits. Validation work at mRNA/protein level defined alterations that were independent of constant physiological ATXN2 functions, but specific for RNA/aggregation toxicity, and progressive across the short lifespan. The earliest changes were detected at three months among Ca2+ channels/transporters (Itpr1, Ryr3, Atp2a2, Atp2a3, Trpc3), IP3 metabolism (Plcg1, Inpp5a, Itpka), and Ca2+-Calmodulin dependent kinases (Camk2a, Camk4). CaMKIV-Sam68 control over alternative splicing of Nrxn1, an adhesion component of glutamatergic synapses between granule and Purkinje neurons, was found to be affected. Systematic screening of pre/post-synapse components, with dendrite morphology assessment, suggested early impairment of CamKIIα abundance together with the weakening of parallel fiber connectivity. These data reveal molecular changes due to ATXN2 pathology, primarily impacting excitability and communication.
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Affiliation(s)
- Aleksandar Arsović
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
| | - Melanie Vanessa Halbach
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
| | - Júlia Canet-Pons
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
| | - Dilhan Esen-Sehir
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Medical Faculty, Goethe University, Heinrich-Hoffmann-Str. 10, 60528 Frankfurt am Main, Germany; (D.E.-S.); (F.F.)
- Faculty of Biosciences, Goethe-University, Max von Laue Strasse 9, 60438 Frankfurt am Main, Germany
| | - Claudia Döring
- Dr. Senckenberg Institute of Pathology, Goethe University Frankfurt, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany;
| | - Florian Freudenberg
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Medical Faculty, Goethe University, Heinrich-Hoffmann-Str. 10, 60528 Frankfurt am Main, Germany; (D.E.-S.); (F.F.)
| | - Nicoletta Czechowska
- Institute of Anatomy, Anatomy and Cell Biology, University of Bonn, Nussallee 10, 53115 Bonn, Germany; (N.C.); (K.S.); (S.L.B.)
| | - Kay Seidel
- Institute of Anatomy, Anatomy and Cell Biology, University of Bonn, Nussallee 10, 53115 Bonn, Germany; (N.C.); (K.S.); (S.L.B.)
| | - Stephan L. Baader
- Institute of Anatomy, Anatomy and Cell Biology, University of Bonn, Nussallee 10, 53115 Bonn, Germany; (N.C.); (K.S.); (S.L.B.)
| | - Suzana Gispert
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
| | - Nesli-Ece Sen
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
- Faculty of Biosciences, Goethe-University, Max von Laue Strasse 9, 60438 Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
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19
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Niewiadomska-Cimicka A, Hache A, Trottier Y. Gene Deregulation and Underlying Mechanisms in Spinocerebellar Ataxias With Polyglutamine Expansion. Front Neurosci 2020; 14:571. [PMID: 32581696 PMCID: PMC7296114 DOI: 10.3389/fnins.2020.00571] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/11/2020] [Indexed: 12/14/2022] Open
Abstract
Polyglutamine spinocerebellar ataxias (polyQ SCAs) include SCA1, SCA2, SCA3, SCA6, SCA7, and SCA17 and constitute a group of adult onset neurodegenerative disorders caused by the expansion of a CAG repeat sequence located within the coding region of specific genes, which translates into polyglutamine tract in the corresponding proteins. PolyQ SCAs are characterized by degeneration of the cerebellum and its associated structures and lead to progressive ataxia and other diverse symptoms. In recent years, gene and epigenetic deregulations have been shown to play a critical role in the pathogenesis of polyQ SCAs. Here, we provide an overview of the functions of wild type and pathogenic polyQ SCA proteins in gene regulation, describe the extent and nature of gene expression changes and their pathological consequences in diseases, and discuss potential avenues to further investigate converging and distinct disease pathways and to develop therapeutic strategies.
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Affiliation(s)
- Anna Niewiadomska-Cimicka
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Strasbourg, France
| | - Antoine Hache
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Strasbourg, France
| | - Yvon Trottier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Strasbourg, France
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20
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McLoughlin HS, Moore LR, Paulson HL. Pathogenesis of SCA3 and implications for other polyglutamine diseases. Neurobiol Dis 2020; 134:104635. [PMID: 31669734 PMCID: PMC6980715 DOI: 10.1016/j.nbd.2019.104635] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [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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21
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Sen NE, Arsovic A, Meierhofer D, Brodesser S, Oberschmidt C, Canet-Pons J, Kaya ZE, Halbach MV, Gispert S, Sandhoff K, Auburger G. In Human and Mouse Spino-Cerebellar Tissue, Ataxin-2 Expansion Affects Ceramide-Sphingomyelin Metabolism. Int J Mol Sci 2019; 20:E5854. [PMID: 31766565 PMCID: PMC6928749 DOI: 10.3390/ijms20235854] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 02/08/2023] Open
Abstract
Ataxin-2 (human gene symbol ATXN2) acts during stress responses, modulating mRNA translation and nutrient metabolism. Ataxin-2 knockout mice exhibit progressive obesity, dyslipidemia, and insulin resistance. Conversely, the progressive ATXN2 gain of function due to the fact of polyglutamine (polyQ) expansions leads to a dominantly inherited neurodegenerative process named spinocerebellar ataxia type 2 (SCA2) with early adipose tissue loss and late muscle atrophy. We tried to understand lipid dysregulation in a SCA2 patient brain and in an authentic mouse model. Thin layer chromatography of a patient cerebellum was compared to the lipid metabolome of Atxn2-CAG100-Knockin (KIN) mouse spinocerebellar tissue. The human pathology caused deficits of sulfatide, galactosylceramide, cholesterol, C22/24-sphingomyelin, and gangliosides GM1a/GD1b despite quite normal levels of C18-sphingomyelin. Cerebellum and spinal cord from the KIN mouse showed a consistent decrease of various ceramides with a significant elevation of sphingosine in the more severely affected spinal cord. Deficiency of C24/26-sphingomyelins contrasted with excess C18/20-sphingomyelin. Spinocerebellar expression profiling revealed consistent reductions of CERS protein isoforms, Sptlc2 and Smpd3, but upregulation of Cers2 mRNA, as prominent anomalies in the ceramide-sphingosine metabolism. Reduction of Asah2 mRNA correlated to deficient S1P levels. In addition, downregulations for the elongase Elovl1, Elovl4, Elovl5 mRNAs and ELOVL4 protein explain the deficit of very long-chain sphingomyelin. Reduced ASMase protein levels correlated to the accumulation of long-chain sphingomyelin. Overall, a deficit of myelin lipids was prominent in SCA2 nervous tissue at prefinal stage and not compensated by transcriptional adaptation of several metabolic enzymes. Myelination is controlled by mTORC1 signals; thus, our human and murine observations are in agreement with the known role of ATXN2 yeast, nematode, and mouse orthologs as mTORC1 inhibitors and autophagy promoters.
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Affiliation(s)
- Nesli-Ece Sen
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
- Faculty of Biosciences, Goethe-University, 60438 Frankfurt am Main, Germany
| | - Aleksandar Arsovic
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany;
| | - Susanne Brodesser
- Membrane Biology and Lipid Biochemistry Unit, Life and Medical Sciences Institute, University of Bonn, 53121 Bonn, Germany;
| | - Carola Oberschmidt
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Júlia Canet-Pons
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Zeynep-Ece Kaya
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
- Cerrahpasa School of Medicine, Istanbul University, 34098 Istanbul, Turkey
| | - Melanie-Vanessa Halbach
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Suzana Gispert
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Konrad Sandhoff
- Membrane Biology and Lipid Biochemistry Unit, Life and Medical Sciences Institute, University of Bonn, 53121 Bonn, Germany;
| | - Georg Auburger
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
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22
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Egorova PA, Bezprozvanny IB. Molecular Mechanisms and Therapeutics for Spinocerebellar Ataxia Type 2. Neurotherapeutics 2019; 16:1050-1073. [PMID: 31435879 PMCID: PMC6985344 DOI: 10.1007/s13311-019-00777-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The effective therapeutic treatment and the disease-modifying therapy for spinocerebellar ataxia type 2 (SCA2) (a progressive hereditary disease caused by an expansion of polyglutamine in the ataxin-2 protein) is not available yet. At present, only symptomatic treatment and methods of palliative care are prescribed to the patients. Many attempts were made to study the physiological, molecular, and biochemical changes in SCA2 patients and in a variety of the model systems to find new therapeutic targets for SCA2 treatment. A better understanding of the uncovered molecular mechanisms of the disease allowed the scientific community to develop strategies of potential therapy and helped to create some promising therapeutic approaches for SCA2 treatment. Recent progress in this field will be discussed in this review article.
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Affiliation(s)
- Polina A Egorova
- Laboratory of Molecular Neurodegeneration, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, 195251, Russia
| | - Ilya B Bezprozvanny
- Laboratory of Molecular Neurodegeneration, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, 195251, Russia.
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, ND12.200, Dallas, Texas, 75390, USA.
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23
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Dysregulated autophagy as a new aspect of the molecular pathogenesis of Krabbe disease. Neurobiol Dis 2019; 129:195-207. [DOI: 10.1016/j.nbd.2019.05.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/08/2019] [Accepted: 05/13/2019] [Indexed: 12/19/2022] Open
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24
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Antisense oligonucleotide therapy rescues aggresome formation in a novel spinocerebellar ataxia type 3 human embryonic stem cell line. Stem Cell Res 2019; 39:101504. [PMID: 31374463 DOI: 10.1016/j.scr.2019.101504] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/11/2019] [Accepted: 07/15/2019] [Indexed: 01/01/2023] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3) is a fatal, late-onset neurodegenerative disorder characterized by selective neuropathology in the brainstem, cerebellum, spinal cord, and substantia nigra. Here we report the first NIH-approved human embryonic stem cell (hESC) line derived from an embryo harboring the SCA3 mutation. Referred to as SCA3-hESC, this line is heterozygous for the mutant polyglutamine-encoding CAG repeat expansion in the ATXN3 gene. We observed relevant molecular hallmarks of the human disease at all differentiation stages from stem cells to cortical neurons, including robust ATXN3 aggregation and altered expression of key components of the protein quality control machinery. In addition, SCA3-hESCs exhibit nuclear accumulation of mutant ATXN3 and form p62-positive aggresomes. Finally, antisense oligonucleotide-mediated reduction of ATXN3 markedly suppressed aggresome formation. The SCA3-hESC line offers a unique and highly relevant human disease model that holds strong potential to advance understanding of SCA3 disease mechanisms and facilitate the evaluation of candidate therapies for SCA3.
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25
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Lastres-Becker I, Nonis D, Nowock J, Auburger G. New alternative splicing variants of the ATXN2 transcript. Neurol Res Pract 2019; 1:22. [PMID: 33324888 PMCID: PMC7650068 DOI: 10.1186/s42466-019-0025-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 05/09/2019] [Indexed: 12/12/2022] Open
Abstract
Background Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant disorder with progressive degeneration of cerebellar Purkinje cells and selective loss of neurons in the brainstem. This neurodegenerative disorder is caused by the expansion of a polyglutamine domain in ataxin-2. Ataxin-2 is composed of 1312 amino acids, has a predicted molecular weight of 150-kDa and is widely expressed in neuronal and non-neuronal tissues. To date, the putative functions of ataxin-2 on mRNA translation and endocytosis remain ill-defined. Differential splicing with a lack of exons 10 and 21 was described in humans, and additional splicing of exon 11 in mice. In this study, we observed that the molecular size of transfected full-length wild-type ataxin-2 (22 glutamines) is different from endogenous ataxin-2 and that this variation could not be explained by the previously published splice variants alone. Methods Quantitative immunoblots and qualitative reverse-transcriptase polymerase-chain-reaction (RT-PCR) were used to characterize isoform variants, before sequencing was employed for validation. Results We report the characterization of further splice variants of ataxin-2 in different human cell lines and in mouse and human brain. Using RT-PCR from cell lines HeLa, HEK293 and COS-7 throughout the open reading frame of ataxin-2 together with PCR-sequencing, we found novel splice variants lacking exon 12 and exon 24. These findings were corroborated in murine and human brain. The splice variants were also found in human skin fibroblasts from SCA2 patients and controls, indicating that the polyglutamine expansion does not abolish the splicing. Conclusions Given that Ataxin-2 interacts with crucial splice modulators such as TDP-43 and modulates the risk of Amyotrophic Lateral Sclerosis, its own splice isoforms may become relevant in brain tissue to monitor the RNA processing during disease progression and neuroprotective therapy.
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Affiliation(s)
- Isabel Lastres-Becker
- Experimental Neurology, Goethe University Medical Faculty, Building 89, 3rd floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany.,Present address: Department of Biochemistry, Faculty of Medicine, Universidad Autonoma of Madrid, Madrid, Spain
| | - David Nonis
- Experimental Neurology, Goethe University Medical Faculty, Building 89, 3rd floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Joachim Nowock
- Experimental Neurology, Goethe University Medical Faculty, Building 89, 3rd floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Goethe University Medical Faculty, Building 89, 3rd floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
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26
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McLoughlin HS, Moore LR, Chopra R, Komlo R, McKenzie M, Blumenstein KG, Zhao H, Kordasiewicz HB, Shakkottai VG, Paulson HL. Oligonucleotide therapy mitigates disease in spinocerebellar ataxia type 3 mice. Ann Neurol 2018; 84:64-77. [PMID: 29908063 PMCID: PMC6119475 DOI: 10.1002/ana.25264] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 05/16/2018] [Accepted: 05/21/2018] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease, is the most common dominantly inherited ataxia. Despite advances in understanding this CAG repeat/polyglutamine expansion disease, there are still no therapies to alter its progressive fatal course. Here, we investigate whether an antisense oligonucleotide (ASO) targeting the SCA3 disease gene, ATXN3, can prevent molecular, neuropathological, electrophysiological, and behavioral features of the disease in a mouse model of SCA3. METHODS The top ATXN3-targeting ASO from an in vivo screen was injected intracerebroventricularly into early symptomatic transgenic SCA3 mice that express the full human disease gene and recapitulate key disease features. Following a single ASO treatment at 8 weeks of age, mice were evaluated longitudinally for ATXN3 suppression and rescue of disease-associated pathological changes. Mice receiving an additional repeat injection at 21 weeks were evaluated longitudinally up to 29 weeks for motor performance. RESULTS The ATXN3-targeting ASO achieved sustained reduction of polyglutamine-expanded ATXN3 up to 8 weeks after treatment and prevented oligomeric and nuclear accumulation of ATXN3 up to at least 14 weeks after treatment. Longitudinal ASO therapy rescued motor impairment in SCA3 mice, and this rescue was associated with a recovery of defects in Purkinje neuron firing frequency and afterhyperpolarization. INTERPRETATION This preclinical study established efficacy of ATXN3-targeted ASOs as a disease-modifying therapeutic strategy for SCA3. These results support further efforts to develop ASOs for human clinical trials in this polyglutamine disease as well as in other dominantly inherited disorders caused by toxic gain of function. Ann Neurol 2018;83:64-77.
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Affiliation(s)
| | - Lauren R. Moore
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Ravi Chopra
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Robert Komlo
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Megan McKenzie
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Kate G. Blumenstein
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Hien Zhao
- Ionis Pharmaceuticals, Carlsbad, CA 92008, USA
| | | | | | - Henry L. Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
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27
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Dilemma of multiple system atrophy and spinocerebellar ataxias. J Neurol 2018; 265:2764-2772. [DOI: 10.1007/s00415-018-8876-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 04/19/2018] [Accepted: 04/20/2018] [Indexed: 12/17/2022]
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28
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Velázquez-Pérez LC, Rodríguez-Labrada R, Fernandez-Ruiz J. Spinocerebellar Ataxia Type 2: Clinicogenetic Aspects, Mechanistic Insights, and Management Approaches. Front Neurol 2017; 8:472. [PMID: 28955296 PMCID: PMC5601978 DOI: 10.3389/fneur.2017.00472] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 08/25/2017] [Indexed: 12/14/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant cerebellar ataxia that occurs as a consequence of abnormal CAG expansions in the ATXN2 gene. Progressive clinical features result from the neurodegeneration of cerebellum and extra-cerebellar structures including the pons, the basal ganglia, and the cerebral cortex. Clinical, electrophysiological, and imaging approaches have been used to characterize the natural history of the disease, allowing its classification into four distinct stages, with special emphasis on the prodromal stage, which is characterized by a plethora of motor and non-motor features. Neuropathological investigations of brain tissue from SCA2 patients reveal a widespread involvement of multiple brain systems, mainly cerebellar and brainstem systems. Recent findings linking ataxin-2 intermediate expansions to other neurodegenerative diseases such as amyotrophic lateral sclerosis have provided insights into the ataxin-2-related toxicity mechanism in neurodegenerative diseases and have raised new ethical challenges to molecular predictive diagnosis of SCA2. No effective neuroprotective therapies are currently available for SCA2 patients, but some therapeutic options such as neurorehabilitation and some emerging neuroprotective drugs have shown palliative benefits.
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Affiliation(s)
- Luis C Velázquez-Pérez
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Medical University of Holguín "Mariana Grajales", Holguín, Cuba
| | - Roberto Rodríguez-Labrada
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Physical Culture School, University of Holguin "Oscar Lucero", Holguín, Cuba
| | - Juan Fernandez-Ruiz
- Department of Physiology, Medicine School, UNAM, Cuernavaca, Mexico.,Psychology School, Universidad Veracruzana, Xalapa, Mexico
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29
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Kuiper EFE, de Mattos EP, Jardim LB, Kampinga HH, Bergink S. Chaperones in Polyglutamine Aggregation: Beyond the Q-Stretch. Front Neurosci 2017; 11:145. [PMID: 28386214 PMCID: PMC5362620 DOI: 10.3389/fnins.2017.00145] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/08/2017] [Indexed: 01/12/2023] Open
Abstract
Expanded polyglutamine (polyQ) stretches in at least nine unrelated proteins lead to inherited neuronal dysfunction and degeneration. The expansion size in all diseases correlates with age at onset (AO) of disease and with polyQ protein aggregation, indicating that the expanded polyQ stretch is the main driving force for the disease onset. Interestingly, there is marked interpatient variability in expansion thresholds for a given disease. Between different polyQ diseases the repeat length vs. AO also indicates the existence of modulatory effects on aggregation of the upstream and downstream amino acid sequences flanking the Q expansion. This can be either due to intrinsic modulation of aggregation by the flanking regions, or due to differential interaction with other proteins, such as the components of the cellular protein quality control network. Indeed, several lines of evidence suggest that molecular chaperones have impact on the handling of different polyQ proteins. Here, we review factors differentially influencing polyQ aggregation: the Q-stretch itself, modulatory flanking sequences, interaction partners, cleavage of polyQ-containing proteins, and post-translational modifications, with a special focus on the role of molecular chaperones. By discussing typical examples of how these factors influence aggregation, we provide more insight on the variability of AO between different diseases as well as within the same polyQ disorder, on the molecular level.
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Affiliation(s)
- E F E Kuiper
- Department of Cell Biology, University Medical Center Groningen, University of Groningen Groningen, Netherlands
| | - Eduardo P de Mattos
- Department of Cell Biology, University Medical Center Groningen, University of GroningenGroningen, Netherlands; Programa de Pós-Graduação em Genética e Biologia Molecular, Department of Genetics, Universidade Federal do Rio Grande do SulPorto Alegre, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto AlegrePorto Alegre, Brazil
| | - Laura B Jardim
- Programa de Pós-Graduação em Genética e Biologia Molecular, Department of Genetics, Universidade Federal do Rio Grande do SulPorto Alegre, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto AlegrePorto Alegre, Brazil; Departamento de Medicina Interna, Universidade Federal do Rio Grande do SulPorto Alegre, Brazil
| | - Harm H Kampinga
- Department of Cell Biology, University Medical Center Groningen, University of Groningen Groningen, Netherlands
| | - Steven Bergink
- Department of Cell Biology, University Medical Center Groningen, University of Groningen Groningen, Netherlands
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30
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Alves-Cruzeiro JMDC, Mendonça L, Pereira de Almeida L, Nóbrega C. Motor Dysfunctions and Neuropathology in Mouse Models of Spinocerebellar Ataxia Type 2: A Comprehensive Review. Front Neurosci 2016; 10:572. [PMID: 28018166 PMCID: PMC5156697 DOI: 10.3389/fnins.2016.00572] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 11/28/2016] [Indexed: 12/16/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant ataxia caused by an expansion of CAG repeats in the exon 1 of the gene ATXN2, conferring a gain of toxic function that triggers the appearance of the disease phenotype. SCA2 is characterized by several symptoms including progressive gait ataxia and dysarthria, slow saccadic eye movements, sleep disturbances, cognitive impairments, and psychological dysfunctions such as insomnia and depression, among others. The available treatments rely on palliative care, which mitigate some of the major symptoms but ultimately fail to block the disease progression. This persistent lack of effective therapies led to the development of several models in yeast, C. elegans, D. melanogaster, and mice to serve as platforms for testing new therapeutic strategies and to accelerate the research on the complex disease mechanisms. In this work, we review 4 transgenic and 1 knock-in mouse that exhibit a SCA2-related phenotype and discuss their usefulness in addressing different scientific problems. The knock-in mice are extremely faithful to the human disease, with late onset of symptoms and physiological levels of mutant ataxin-2, while the other transgenic possess robust and well-characterized motor impairments and neuropathological features. Furthermore, a new BAC model of SCA2 shows promise to study the recently explored role of non-coding RNAs as a major pathogenic mechanism in this devastating disorder. Focusing on specific aspects of the behavior and neuropathology, as well as technical aspects, we provide a highly practical description and comparison of all the models with the purpose of creating a useful resource for SCA2 researchers worldwide.
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Affiliation(s)
| | - Liliana Mendonça
- Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Luís Pereira de Almeida
- Center for Neuroscience and Cell Biology, University of CoimbraCoimbra, Portugal; Faculty of Pharmacy, University of CoimbraCoimbra, Portugal
| | - Clévio Nóbrega
- Department of Biomedical Sciences and Medicine and Center for Biomedical Research, University of Algarve Faro, Portugal
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31
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Sen NE, Drost J, Gispert S, Torres-Odio S, Damrath E, Klinkenberg M, Hamzeiy H, Akdal G, Güllüoğlu H, Başak AN, Auburger G. Search for SCA2 blood RNA biomarkers highlights Ataxin-2 as strong modifier of the mitochondrial factor PINK1 levels. Neurobiol Dis 2016; 96:115-126. [PMID: 27597528 DOI: 10.1016/j.nbd.2016.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/24/2016] [Accepted: 09/01/2016] [Indexed: 12/13/2022] Open
Abstract
Ataxin-2 (ATXN2) polyglutamine domain expansions of large size result in an autosomal dominantly inherited multi-system-atrophy of the nervous system named spinocerebellar ataxia type 2 (SCA2), while expansions of intermediate size act as polygenic risk factors for motor neuron disease (ALS and FTLD) and perhaps also for Levodopa-responsive Parkinson's disease (PD). In view of the established role of ATXN2 for RNA processing in periods of cell stress and the expression of ATXN2 in blood cells such as platelets, we investigated whether global deep RNA sequencing of whole blood from SCA2 patients identifies a molecular profile which might serve as diagnostic biomarker. The bioinformatic analysis of SCA2 blood global transcriptomics revealed various significant effects on RNA processing pathways, as well as the pathways of Huntington's disease and PD where mitochondrial dysfunction is crucial. Notably, an induction of PINK1 and PARK7 expression was observed. Conversely, expression of Pink1 was severely decreased upon global transcriptome profiling of Atxn2-knockout mouse cerebellum and liver, in parallel to strong effects on Opa1 and Ghitm, which encode known mitochondrial dynamics regulators. These results were validated by quantitative PCR and immunoblots. Starvation stress of human SH-SY5Y neuroblastoma cells led to a transcriptional phasic induction of ATXN2 in parallel to PINK1, and the knockdown of one enhanced the expression of the other during stress response. These findings suggest that ATXN2 may modify the known PINK1 roles for mitochondrial quality control and autophagy during cell stress. Given that PINK1 is responsible for autosomal recessive juvenile PD, this genetic interaction provides a concept how the degeneration of nigrostriatal dopaminergic neurons and the Parkinson phenotype may be triggered by ATXN2 mutations.
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Affiliation(s)
- Nesli Ece Sen
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany; Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Boğaziçi University, 34342 Istanbul, Turkey
| | - Jessica Drost
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Suzana Gispert
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Sylvia Torres-Odio
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Ewa Damrath
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Michael Klinkenberg
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Hamid Hamzeiy
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Boğaziçi University, 34342 Istanbul, Turkey
| | - Gülden Akdal
- Department of Neurology, Faculty of Medicine, Dokuz Eylül University, Izmir, Turkey
| | - Halil Güllüoğlu
- Department of Neurology, Faculty of Medicine, Izmir University, Izmir, Turkey
| | - A Nazlı Başak
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Boğaziçi University, 34342 Istanbul, Turkey.
| | - Georg Auburger
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany.
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