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Sujkowski A, Ranxhi B, Bangash ZR, Chbihi ZM, Prifti MV, Qadri Z, Alam N, Todi SV, Tsou WL. Progressive degeneration in a new Drosophila model of spinocerebellar ataxia type 7. Sci Rep 2024; 14:14332. [PMID: 38906973 PMCID: PMC11192756 DOI: 10.1038/s41598-024-65172-4] [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: 11/10/2023] [Accepted: 06/18/2024] [Indexed: 06/23/2024] Open
Abstract
Spinocerebellar ataxia type 7 (SCA7) is a progressive neurodegenerative disorder resulting from abnormal expansion of an uninterrupted polyglutamine (polyQ) repeat in its disease protein, ataxin-7 (ATXN7). ATXN7 is part of Spt-Ada-Gcn5 acetyltransferase (SAGA), an evolutionarily conserved transcriptional coactivation complex with critical roles in chromatin remodeling, cell signaling, neurodifferentiation, mitochondrial health and autophagy. SCA7 is dominantly inherited and characterized by genetic anticipation and high repeat-length instability. Patients with SCA7 experience progressive ataxia, atrophy, spasticity, and blindness. There is currently no cure for SCA7, and therapies are aimed at alleviating symptoms to increase quality of life. Here, we report novel Drosophila lines of SCA7 with polyQ repeats in wild-type and human disease patient range. We find that ATXN7 expression has age- and polyQ repeat length-dependent reduction in fruit fly survival and retinal instability, concomitant with increased ATXN7 protein aggregation. These new lines will provide important insight on disease progression that can be used in the future to identify therapeutic targets for SCA7 patients.
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Affiliation(s)
- Alyson Sujkowski
- Department of Pharmacology, Wayne State University School of Medicine, 540 E Canfield, Scott Hall Rm 3108, Detroit, MI, 48201, USA
| | - Bedri Ranxhi
- Department of Pharmacology, Wayne State University School of Medicine, 540 E Canfield, Scott Hall Rm 3108, Detroit, MI, 48201, USA
| | - Zoya R Bangash
- Department of Pharmacology, Wayne State University School of Medicine, 540 E Canfield, Scott Hall Rm 3108, Detroit, MI, 48201, USA
| | - Zachary M Chbihi
- Department of Pharmacology, Wayne State University School of Medicine, 540 E Canfield, Scott Hall Rm 3108, Detroit, MI, 48201, USA
| | - Matthew V Prifti
- Department of Pharmacology, Wayne State University School of Medicine, 540 E Canfield, Scott Hall Rm 3108, Detroit, MI, 48201, USA
| | - Zaina Qadri
- Department of Pharmacology, Wayne State University School of Medicine, 540 E Canfield, Scott Hall Rm 3108, Detroit, MI, 48201, USA
| | - Nadir Alam
- Department of Pharmacology, Wayne State University School of Medicine, 540 E Canfield, Scott Hall Rm 3108, Detroit, MI, 48201, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, 540 E Canfield, Scott Hall Rm 3108, Detroit, MI, 48201, USA
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University School of Medicine, 540 E Canfield, Scott Hall Rm 3108, Detroit, MI, 48201, USA.
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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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Potapenko A, Davidson JM, Lee A, Laird AS. The deubiquitinase function of ataxin-3 and its role in the pathogenesis of Machado-Joseph disease and other diseases. Biochem J 2024; 481:461-480. [PMID: 38497605 PMCID: PMC11088879 DOI: 10.1042/bcj20240017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/04/2024] [Accepted: 03/07/2024] [Indexed: 03/19/2024]
Abstract
Machado-Joseph disease (MJD) is a devastating and incurable neurodegenerative disease characterised by progressive ataxia, difficulty speaking and swallowing. Consequently, affected individuals ultimately become wheelchair dependent, require constant care, and face a shortened life expectancy. The monogenic cause of MJD is expansion of a trinucleotide (CAG) repeat region within the ATXN3 gene, which results in polyglutamine (polyQ) expansion within the resultant ataxin-3 protein. While it is well established that the ataxin-3 protein functions as a deubiquitinating (DUB) enzyme and is therefore critically involved in proteostasis, several unanswered questions remain regarding the impact of polyQ expansion in ataxin-3 on its DUB function. Here we review the current literature surrounding ataxin-3's DUB function, its DUB targets, and what is known regarding the impact of polyQ expansion on ataxin-3's DUB function. We also consider the potential neuroprotective effects of ataxin-3's DUB function, and the intersection of ataxin-3's role as a DUB enzyme and regulator of gene transcription. Ataxin-3 is the principal pathogenic protein in MJD and also appears to be involved in cancer. As aberrant deubiquitination has been linked to both neurodegeneration and cancer, a comprehensive understanding of ataxin-3's DUB function is important for elucidating potential therapeutic targets in these complex conditions. In this review, we aim to consolidate knowledge of ataxin-3 as a DUB and unveil areas for future research to aid therapeutic targeting of ataxin-3's DUB function for the treatment of MJD and other diseases.
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Affiliation(s)
- Anastasiya Potapenko
- Motor Neuron Disease Research Centre, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Jennilee M. Davidson
- Motor Neuron Disease Research Centre, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Albert Lee
- Motor Neuron Disease Research Centre, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Angela S. Laird
- Motor Neuron Disease Research Centre, Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW 2109, Australia
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4
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Sujkowski AL, Ranxhi B, Prifti MV, Alam N, Todi SV, Tsou WL. Progressive degeneration in a new Drosophila model of Spinocerebellar Ataxia type 7. RESEARCH SQUARE 2023:rs.3.rs-3592641. [PMID: 38045332 PMCID: PMC10690306 DOI: 10.21203/rs.3.rs-3592641/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Spinocerebellar ataxia type 7 (SCA7) is a progressive neurodegenerative disorder resulting from abnormal expansion of polyglutamine (polyQ) in its disease protein, ataxin-7 (ATXN7). ATXN7 is part of Spt-Ada-Gcn5 acetyltransferase (SAGA), an evolutionarily conserved transcriptional coactivation complex with critical roles in chromatin remodeling, cell signaling, neurodifferentiation, mitochondrial health and autophagy. SCA7 is dominantly inherited and characterized by genetic anticipation and high repeat-length instability. Patients with SCA7 experience progressive ataxia, atrophy, spasticity, and blindness. There is currently no cure for SCA7, and therapies are aimed at alleviating symptoms to increase quality of life. Here, we report novel Drosophila lines of SCA7 with polyQ repeats in wild-type and human disease patient range. We find that ATXN7 expression has age- and polyQ repeat length-dependent reduction in survival and retinal instability, concomitant with increased ATXN7 protein aggregation. These new lines will provide important insight on disease progression that can be used in the future to identify therapeutic targets for SCA7 patients.
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Affiliation(s)
| | - Bedri Ranxhi
- Department of Pharmacology, Wayne State University School of Medicine
| | - Matthew V Prifti
- Department of Pharmacology, Wayne State University School of Medicine
| | - Nadir Alam
- Department of Pharmacology, Wayne State University School of Medicine
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine
- Department of Neurology, Wayne State University School of Medicine
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University School of Medicine
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5
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Blount JR, Patel NC, Libohova K, Harris AL, Tsou WL, Sujkowski A, Todi SV. Lysine 117 on ataxin-3 modulates toxicity in Drosophila models of Spinocerebellar Ataxia Type 3. J Neurol Sci 2023; 454:120828. [PMID: 37865002 PMCID: PMC10841544 DOI: 10.1016/j.jns.2023.120828] [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: 08/01/2023] [Revised: 09/14/2023] [Accepted: 10/04/2023] [Indexed: 10/23/2023]
Abstract
Ataxin-3 (Atxn3) is a deubiquitinase with a polyglutamine (polyQ) repeat tract whose abnormal expansion causes the neurodegenerative disease, Spinocerebellar Ataxia Type 3 (SCA3; also known as Machado-Joseph Disease). The ubiquitin chain cleavage properties of Atxn3 are enhanced when the enzyme is itself ubiquitinated at lysine (K) at position 117: in vitro, K117-ubiqutinated Atxn3 cleaves poly-ubiquitin markedly more rapidly compared to its unmodified counterpart. How polyQ expansion causes SCA3 remains unclear. To gather insights into the biology of disease of SCA3, here we posited the question: is K117 important for toxicity caused by pathogenic Atxn3? To answer this question, we generated transgenic Drosophila lines that express full-length, human, pathogenic Atxn3 with 80 polyQ with an intact or mutated K117. We found that mutating K117 mildly enhances the toxicity and aggregation of pathogenic Atxn3. An additional transgenic line that expresses Atxn3 without any K residues confirms increased aggregation of pathogenic Atxn3 whose ubiquitination is perturbed. These findings suggest that Atxn3 ubiquitination is a regulatory step of SCA3, in part by modulating its aggregation.
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Affiliation(s)
- Jessica R Blount
- Department of Pharmacology, Wayne State University, United States of America
| | - Nikhil C Patel
- Department of Pharmacology, Wayne State University, United States of America
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University, United States of America
| | - Autumn L Harris
- Department of Pharmacology, Wayne State University, United States of America; Maximizing Access to Research Careers, Wayne State University, United States of America
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University, United States of America
| | - Alyson Sujkowski
- Department of Pharmacology, Wayne State University, United States of America.
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University, United States of America; Maximizing Access to Research Careers, Wayne State University, United States of America; Department of Neurology, Wayne State University, United States of America.
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6
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Sujkowski AL, Ranxhi B, Prifti MV, Alam N, Todi SV, Tsou WL. Progressive degeneration in a new Drosophila model of Spinocerebellar Ataxia type 7. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.07.566106. [PMID: 37986914 PMCID: PMC10659390 DOI: 10.1101/2023.11.07.566106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Spinocerebellar ataxia type 7 (SCA7) is a progressive neurodegenerative disorder resulting from abnormal expansion of polyglutamine (polyQ) in its disease protein, ataxin-7 (ATXN7). ATXN7 is part of Spt-Ada-Gcn5 acetyltransferase (SAGA), an evolutionarily conserved transcriptional coactivation complex with critical roles in chromatin remodeling, cell signaling, neurodifferentiation, mitochondrial health and autophagy. SCA7 is dominantly inherited and characterized by genetic anticipation and high repeat-length instability. Patients with SCA7 experience progressive ataxia, atrophy, spasticity, and blindness. There is currently no cure for SCA7, and therapies are aimed at alleviating symptoms to increase quality of life. Here, we report novel Drosophila lines of SCA7 with polyQ repeats in wild-type and human disease patient range. We find that ATXN7 expression has age- and polyQ repeat length-dependent reduction in survival and retinal instability, concomitant with increased ATXN7 protein aggregation. These new lines will provide important insight on disease progression that can be used in the future to identify therapeutic targets for SCA7 patients.
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7
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Patel N, Alam N, Libohova K, Dulay R, Todi SV, Sujkowski A. Phenotypic defects from the expression of wild-type and pathogenic TATA-binding proteins in new Drosophila models of Spinocerebellar Ataxia Type 17. G3 (BETHESDA, MD.) 2023; 13:jkad180. [PMID: 37551423 PMCID: PMC10542169 DOI: 10.1093/g3journal/jkad180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 01/25/2023] [Accepted: 07/19/2023] [Indexed: 08/09/2023]
Abstract
Spinocerebellar Ataxia Type 17 (SCA17) is the most recently identified member of the polyglutamine (polyQ) family of disorders, resulting from abnormal CAG/CAA expansion in the TATA box-binding protein (TBP), an initiation factor essential for of all eukaryotic transcription. A largely autosomal dominant inherited disease, SCA17, is unique in both its heterogeneous clinical presentation and low incidence of genetic anticipation, the phenomenon in which subsequent generations inherit longer polyQ expansions that yield earlier and more severe symptom onset. Like other polyQ disease family members, SCA17 patients experience progressive ataxia and dementia, and treatments are limited to preventing symptoms and increasing quality of life. Here, we report 2 new Drosophila models that express human TBP with polyQ repeats in either wild-type or SCA17 patient range. We find that TBP expression has age- and tissue-specific effects on neurodegeneration, with polyQ-expanded SCA17 protein expression generally having more severe effects. In addition, SCA17 model flies accumulate more aggregation-prone TBP, with a greater proportion localizing to the nucleus. These new lines provide a new resource for the biochemical characterization of SCA17 pathology and the future identification of therapeutic targets.
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Affiliation(s)
- Nikhil Patel
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Nadir Alam
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Kozeta Libohova
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Ryan Dulay
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Sokol V Todi
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
- Department of Neurology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Alyson Sujkowski
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI 48201, USA
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Blount JR, Patel NC, Libohova K, Harris AL, Tsou WL, Sujkowski A, Todi SV. Lysine 117 on ataxin-3 modulates toxicity in Drosophila models of Spinocerebellar Ataxia Type 3. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.30.542896. [PMID: 37398109 PMCID: PMC10312518 DOI: 10.1101/2023.05.30.542896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Ataxin-3 (Atxn3) is a deubiquitinase with a polyglutamine (polyQ) repeat tract whose abnormal expansion causes the neurodegenerative disease, Spinocerebellar Ataxia Type 3 (SCA3; also known as Machado-Joseph Disease). The ubiquitin chain cleavage properties of Atxn3 are enhanced when it is ubiquitinated at lysine (K) at position 117. K117-ubiqutinated Atxn3 cleaves poly-ubiquitin more rapidly in vitro compared to its unmodified counterpart and this residue is also important for Atxn3 roles in cell culture and in Drosophila melanogaster . How polyQ expansion causes SCA3 remains unclear. To gather insight into the biology of disease of SCA3, here we posited the question: is K117 important for toxicity caused by Atxn3? We generated transgenic Drosophila lines that express full-length, human, pathogenic Atxn3 with 80 polyQ with an intact or mutated K117. We found that K117 mutation mildly enhances the toxicity and aggregation of pathogenic Atxn3 in Drosophila . An additional transgenic line that expresses Atxn3 without any K residues confirms increased aggregation of pathogenic Atxn3 whose ubiquitination is perturbed. These findings suggest Atxn3 ubiquitination as a regulatory step of SCA3, in part by modulating its aggregation.
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Pereira Sena P, Weber JJ, Bayezit S, Saup R, Incebacak Eltemur RD, Li X, Velic A, Jung J, Macek B, Nguyen HP, Riess O, Schmidt T. Implications of specific lysine residues within ataxin-3 for the molecular pathogenesis of Machado-Joseph disease. Front Mol Neurosci 2023; 16:1133271. [PMID: 37273907 PMCID: PMC10235640 DOI: 10.3389/fnmol.2023.1133271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 05/03/2023] [Indexed: 06/06/2023] Open
Abstract
Lysine residues are one of the main sites for posttranslational modifications of proteins, and lysine ubiquitination of the Machado-Joseph disease protein ataxin-3 is implicated in its cellular function and polyglutamine expansion-dependent toxicity. Despite previously undertaken efforts, the individual roles of specific lysine residues of the ataxin-3 sequence are not entirely understood and demand further analysis. By retaining single lysine residues of otherwise lysine-free wild-type and polyglutamine-expanded ataxin-3, we assessed the effects of a site-limited modifiability on ataxin-3 protein levels, aggregation propensity, localization, and stability. We confirmed earlier findings that levels of lysine-free ataxin-3 are reduced due to its decreased stability, which led to a diminished load of SDS-insoluble species of its polyglutamine-expanded form. The isolated presence of several single lysine residues within the N-terminus of polyglutamine-expanded ataxin-3 significantly restored its aggregate levels, with highest fold changes induced by the presence of lysine 8 or lysine 85, respectively. Ataxin-3 lacking all lysine residues presented a slightly increased nuclear localization, which was counteracted by the reintroduction of lysine 85, whereas presence of either lysine 8 or lysine 85 led to a significantly higher ataxin-3 stability. Moreover, lysine-free ataxin-3 showed increased toxicity and binding to K48-linked polyubiquitin chains, whereas the reintroduction of lysine 85, located between the ubiquitin-binding sites 1 and 2 of ataxin-3, normalized its binding affinity. Overall, our data highlight the relevance of lysine residues 8 and 85 of ataxin-3 and encourage further analyses, to evaluate the potential of modulating posttranslational modifications of these sites for influencing pathophysiological characteristics of the Machado-Joseph disease protein.
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Affiliation(s)
- Priscila Pereira Sena
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Jonasz Jeremiasz Weber
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
- Department of Human Genetics, Ruhr University Bochum, Bochum, Germany
| | - Sercan Bayezit
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Rafael Saup
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Rana Dilara Incebacak Eltemur
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
- Department of Human Genetics, Ruhr University Bochum, Bochum, Germany
| | - Xiaoling Li
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Ana Velic
- Proteome Center Tübingen, University of Tübingen, Tübingen, Germany
| | - Jaqueline Jung
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Boris Macek
- Proteome Center Tübingen, University of Tübingen, Tübingen, Germany
| | - Huu Phuc Nguyen
- Department of Human Genetics, Ruhr University Bochum, Bochum, Germany
| | - Olaf Riess
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Thorsten Schmidt
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
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Grønbæk-Thygesen M, Kampmeyer C, Hofmann K, Hartmann-Petersen R. The moonlighting of RAD23 in DNA repair and protein degradation. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194925. [PMID: 36863450 DOI: 10.1016/j.bbagrm.2023.194925] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 02/20/2023] [Accepted: 02/23/2023] [Indexed: 03/04/2023]
Abstract
A moonlighting protein is one, which carries out multiple, often wholly unrelated, functions. The RAD23 protein is a fascinating example of this, where the same polypeptide and the embedded domains function independently in both nucleotide excision repair (NER) and protein degradation via the ubiquitin-proteasome system (UPS). Hence, through direct binding to the central NER component XPC, RAD23 stabilizes XPC and contributes to DNA damage recognition. Conversely, RAD23 also interacts directly with the 26S proteasome and ubiquitylated substrates to mediate proteasomal substrate recognition. In this function, RAD23 activates the proteolytic activity of the proteasome and engages specifically in well-characterized degradation pathways through direct interactions with E3 ubiquitin-protein ligases and other UPS components. Here, we summarize the past 40 years of research into the roles of RAD23 in NER and the UPS.
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Affiliation(s)
- Martin Grønbæk-Thygesen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Denmark.
| | - Caroline Kampmeyer
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Denmark
| | - Kay Hofmann
- Institute for Genetics, University of Cologne, Germany
| | - Rasmus Hartmann-Petersen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Denmark.
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11
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Prifti MV, Libohova K, Harris AL, Tsou WL, Todi SV. Ubiquitin-binding site 1 of pathogenic ataxin-3 regulates its toxicity in Drosophila models of Spinocerebellar Ataxia Type 3. Front Neurosci 2023; 16:1112688. [PMID: 36733922 PMCID: PMC9887036 DOI: 10.3389/fnins.2022.1112688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 12/21/2022] [Indexed: 01/18/2023] Open
Abstract
Spinocerebellar Ataxia Type 3 (SCA3) is a member of the family of polyglutamine (polyQ) diseases that are caused by anomalous CAG triplet repeat expansions in several genes. SCA3 results from abnormal polyQ expansion in the deubiquitinase (DUB), ataxin-3 (Atxn3). To understand the role of the different domains of mutant Atxn3 on its pathogenicity, with the hope that they can be explored for therapeutic interventions, we have systematically studied their individual and collective effects on its toxicity. One such domain is ubiquitin-binding site 1 (UbS1) on the catalytic domain of Atxn3; UbS1 is necessary for the enzymatic activity of Atxn3. Here, we investigated the importance of UbS1 on the toxicity of pathogenic Atxn3. We generated transgenic Drosophila melanogaster lines that express polyQ-expanded Atxn3 with and without a functional UbS1. We found that mutating UbS1 markedly exacerbates the toxicity of pathogenic Atxn3. Additional studies indicated that UbS1 regulates the toxicity of Atxn3 not by affecting its aggregation or sub-cellular localization, but by impacting its role in ubiquitin processing. Our findings provide additional insights into the role of Atxn3's domains in the pathogenicity of SCA3.
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Affiliation(s)
- Matthew V. Prifti
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Kozeta Libohova
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Autumn L. Harris
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI, United States,Maximizing Access to Research Careers Program, Wayne State University, Detroit, MI, United States
| | - Wei-Ling Tsou
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Sokol V. Todi
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, MI, United States,Maximizing Access to Research Careers Program, Wayne State University, Detroit, MI, United States,Department of Neurology, School of Medicine, Wayne State University, Detroit, MI, United States,*Correspondence: Sokol V. Todi,
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12
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Johnson SL, Tsou WL, Prifti MV, Harris AL, Todi SV. A survey of protein interactions and posttranslational modifications that influence the polyglutamine diseases. Front Mol Neurosci 2022; 15:974167. [PMID: 36187346 PMCID: PMC9515312 DOI: 10.3389/fnmol.2022.974167] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 07/27/2022] [Indexed: 01/20/2023] Open
Abstract
The presence and aggregation of misfolded proteins has deleterious effects in the nervous system. Among the various diseases caused by misfolded proteins is the family of the polyglutamine (polyQ) disorders. This family comprises nine members, all stemming from the same mutation—the abnormal elongation of a polyQ repeat in nine different proteins—which causes protein misfolding and aggregation, cellular dysfunction and disease. While it is the same type of mutation that causes them, each disease is distinct: it is influenced by regions and domains that surround the polyQ repeat; by proteins with which they interact; and by posttranslational modifications they receive. Here, we overview the role of non-polyQ regions that control the pathogenicity of the expanded polyQ repeat. We begin by introducing each polyQ disease, the genes affected, and the symptoms experienced by patients. Subsequently, we provide a survey of protein-protein interactions and posttranslational modifications that regulate polyQ toxicity. We conclude by discussing shared processes and pathways that bring some of the polyQ diseases together and may serve as common therapeutic entry points for this family of incurable disorders.
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Affiliation(s)
- Sean L. Johnson
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
| | - Matthew V. Prifti
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
| | - Autumn L. Harris
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
- Maximizing Access to Research Careers (MARC) Program, Wayne State University, Detroit, MI, United States
| | - Sokol V. Todi
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
- Maximizing Access to Research Careers (MARC) Program, Wayne State University, Detroit, MI, United States
- Department of Neurology, Wayne State University, Detroit, MI, United States
- *Correspondence: Sokol V. Todi,
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13
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KPNB1 modulates the Machado-Joseph disease protein ataxin-3 through activation of the mitochondrial protease CLPP. Cell Mol Life Sci 2022; 79:401. [PMID: 35794401 PMCID: PMC9259533 DOI: 10.1007/s00018-022-04372-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/25/2022] [Accepted: 05/11/2022] [Indexed: 11/17/2022]
Abstract
Machado–Joseph disease (MJD) is characterized by a pathological expansion of the polyglutamine (polyQ) tract within the ataxin-3 protein. Despite its primarily cytoplasmic localization, polyQ-expanded ataxin-3 accumulates in the nucleus and forms intranuclear aggregates in the affected neurons. Due to these histopathological hallmarks, the nucleocytoplasmic transport machinery has garnered attention as an important disease relevant mechanism. Here, we report on MJD cell model-based analysis of the nuclear transport receptor karyopherin subunit beta-1 (KPNB1) and its implications in the molecular pathogenesis of MJD. Although directly interacting with both wild-type and polyQ-expanded ataxin-3, modulating KPNB1 did not alter the intracellular localization of ataxin-3. Instead, overexpression of KPNB1 reduced ataxin-3 protein levels and the aggregate load, thereby improving cell viability. On the other hand, its knockdown and inhibition resulted in the accumulation of soluble and insoluble ataxin-3. Interestingly, the reduction of ataxin-3 was apparently based on protein fragmentation independent of the classical MJD-associated proteolytic pathways. Label-free quantitative proteomics and knockdown experiments identified mitochondrial protease CLPP as a potential mediator of the ataxin-3-degrading effect induced by KPNB1. We confirmed reduction of KPNB1 protein levels in MJD by analyzing two MJD transgenic mouse models and induced pluripotent stem cells (iPSCs) derived from MJD patients. Our results reveal a yet undescribed regulatory function of KPNB1 in controlling the turnover of ataxin-3, thereby highlighting a new potential target of therapeutic value for MJD.
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14
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Johnson SL, Prifti MV, Sujkowski A, Libohova K, Blount JR, Hong L, Tsou WL, Todi SV. Drosophila as a Model of Unconventional Translation in Spinocerebellar Ataxia Type 3. Cells 2022; 11:cells11071223. [PMID: 35406787 PMCID: PMC8997593 DOI: 10.3390/cells11071223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 03/29/2022] [Accepted: 03/31/2022] [Indexed: 12/21/2022] Open
Abstract
RNA toxicity contributes to diseases caused by anomalous nucleotide repeat expansions. Recent work demonstrated RNA-based toxicity from repeat-associated, non-AUG-initiated translation (RAN translation). RAN translation occurs around long nucleotide repeats that form hairpin loops, allowing for translation initiation in the absence of a start codon that results in potentially toxic, poly-amino acid repeat-containing proteins. Discovered in Spinocerebellar Ataxia Type (SCA) 8, RAN translation has been documented in several repeat-expansion diseases, including in the CAG repeat-dependent polyglutamine (polyQ) disorders. The ATXN3 gene, which causes SCA3, also known as Machado–Joseph Disease (MJD), contains a CAG repeat that is expanded in disease. ATXN3 mRNA possesses features linked to RAN translation. In this paper, we examined the potential contribution of RAN translation to SCA3/MJD in Drosophila by using isogenic lines that contain homomeric or interrupted CAG repeats. We did not observe unconventional translation in fly neurons or glia. However, our investigations indicate differential toxicity from ATXN3 protein-encoding mRNA that contains pure versus interrupted CAG repeats. Additional work suggests that this difference may be due in part to toxicity from homomeric CAG mRNA. We conclude that Drosophila is not suitable to model RAN translation for SCA3/MJD, but offers clues into the potential pathogenesis stemming from CAG repeat-containing mRNA in this disorder.
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Affiliation(s)
- Sean L. Johnson
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Matthew V. Prifti
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Alyson Sujkowski
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Jessica R. Blount
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Luke Hong
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
| | - Sokol V. Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; (S.L.J.); (M.V.P.); (A.S.); (K.L.); (J.R.B.); (L.H.); (W.-L.T.)
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Correspondence:
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15
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Johnson SL, Libohova K, Blount JR, Sujkowski AL, Prifti MV, Tsou WL, Todi SV. Targeting the VCP-binding motif of ataxin-3 improves phenotypes in Drosophila models of Spinocerebellar Ataxia Type 3. Neurobiol Dis 2021; 160:105516. [PMID: 34563642 PMCID: PMC8693084 DOI: 10.1016/j.nbd.2021.105516] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/23/2021] [Accepted: 09/21/2021] [Indexed: 11/28/2022] Open
Abstract
Of the family of polyglutamine (polyQ) neurodegenerative diseases, Spinocerebellar Ataxia Type 3 (SCA3) is the most common. Like other polyQ diseases, SCA3 stems from abnormal expansions in the CAG triplet repeat of its disease gene resulting in elongated polyQ repeats within its protein, ataxin-3. Various ataxin-3 protein domains contribute to its toxicity, including the valosin-containing protein (VCP)-binding motif (VBM). We previously reported that VCP, a homo-hexameric protein, enhances pathogenic ataxin-3 aggregation and exacerbates its toxicity. These findings led us to explore the impact of targeting the SCA3 protein by utilizing a decoy protein comprising the N-terminus of VCP (N-VCP) that binds ataxin-3's VBM. The notion was that N-VCP would reduce binding of ataxin-3 to VCP, decreasing its aggregation and toxicity. We found that expression of N-VCP in Drosophila melanogaster models of SCA3 ameliorated various phenotypes, coincident with reduced ataxin-3 aggregation. This protective effect was specific to pathogenic ataxin-3 and depended on its VBM. Increasing the amount of N-VCP resulted in further phenotype improvement. Our work highlights the protective potential of targeting the VCP-ataxin-3 interaction in SCA3, a key finding in the search for therapeutic opportunities for this incurable disorder.
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Affiliation(s)
- Sean L Johnson
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Jessica R Blount
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Alyson L Sujkowski
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Matthew V Prifti
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA; Department of Neurology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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16
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Snyder NA, Silva GM. Deubiquitinating enzymes (DUBs): Regulation, homeostasis, and oxidative stress response. J Biol Chem 2021; 297:101077. [PMID: 34391779 PMCID: PMC8424594 DOI: 10.1016/j.jbc.2021.101077] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 12/17/2022] Open
Abstract
Ubiquitin signaling is a conserved, widespread, and dynamic process in which protein substrates are rapidly modified by ubiquitin to impact protein activity, localization, or stability. To regulate this process, deubiquitinating enzymes (DUBs) counter the signal induced by ubiquitin conjugases and ligases by removing ubiquitin from these substrates. Many DUBs selectively regulate physiological pathways employing conserved mechanisms of ubiquitin bond cleavage. DUB activity is highly regulated in dynamic environments through protein-protein interaction, posttranslational modification, and relocalization. The largest family of DUBs, cysteine proteases, are also sensitive to regulation by oxidative stress, as reactive oxygen species (ROS) directly modify the catalytic cysteine required for their enzymatic activity. Current research has implicated DUB activity in human diseases, including various cancers and neurodegenerative disorders. Due to their selectivity and functional roles, DUBs have become important targets for therapeutic development to treat these conditions. This review will discuss the main classes of DUBs and their regulatory mechanisms with a particular focus on DUB redox regulation and its physiological impact during oxidative stress.
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Affiliation(s)
- Nathan A Snyder
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Gustavo M Silva
- Department of Biology, Duke University, Durham, North Carolina, USA.
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17
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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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18
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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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19
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Toulis V, García-Monclús S, de la Peña-Ramírez C, Arenas-Galnares R, Abril JF, Todi SV, Khan N, Garanto A, Costa MDC, Marfany G. The Deubiquitinating Enzyme Ataxin-3 Regulates Ciliogenesis and Phagocytosis in the Retina. Cell Rep 2020; 33:108360. [PMID: 33176149 PMCID: PMC8738964 DOI: 10.1016/j.celrep.2020.108360] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 09/04/2020] [Accepted: 10/17/2020] [Indexed: 01/07/2023] Open
Abstract
Expansion of a CAG repeat in ATXN3 causes the dominant polyglutamine disease spinocerebellar ataxia type 3 (SCA3), yet the physiological role of ATXN3 remains unclear. Here, we focus on unveiling the function of Ataxin-3 (ATXN3) in the retina, a neurological organ amenable to morphological and physiological studies. Depletion of Atxn3 in zebrafish and mice causes morphological and functional retinal alterations and, more precisely, photoreceptor cilium and outer segment elongation, cone opsin mislocalization, and cone hyperexcitation. ATXN3 localizes at the basal body and axoneme of the cilium, supporting its role in regulating ciliary length. Abrogation of Atxn3 expression causes decreased levels of the regulatory protein KEAP1 in the retina and delayed phagosome maturation in the retinal pigment epithelium. We propose that ATXN3 regulates two relevant biological processes in the retina, namely, ciliogenesis and phagocytosis, by modulating microtubule polymerization and microtubule-dependent retrograde transport, thus positing ATXN3 as a causative or modifier gene in retinal/macular dystrophies. Toulis et al. show that depletion of Atxn3 causes retinal morphological and electrophysiological alterations, as well as diminished phagocytosis in vivo and in vitro. ATXN3 regulates retinal ciliogenesis and phagocytosis through the KEAP1-SQSTM1-HDAC6-acetylated tubulin pathway by modulating microtubule polymerization and microtubule-dependent retrograde transport.
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Affiliation(s)
- Vasileios Toulis
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain; CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain; Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Sílvia García-Monclús
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain
| | - Carlos de la Peña-Ramírez
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain
| | - Rodrigo Arenas-Galnares
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain; Institute of Biomedicine (IBUB, IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
| | - Josep F Abril
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain; Institute of Biomedicine (IBUB, IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA; Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Naheed Khan
- Department of Ophthalmology and Visual Sciences, W. K. Kellogg Eye Center, University of Michigan, Ann Arbor, MI, USA
| | - Alejandro Garanto
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain; Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Maria do Carmo Costa
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.
| | - Gemma Marfany
- Departament de Genètica, Microbiologia i Estadística, Avda. Diagonal 643, Universitat de Barcelona, Barcelona 08028, Spain; CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain; Institute of Biomedicine (IBUB, IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain.
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20
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Johnson SL, Ranxhi B, Libohova K, Tsou WL, Todi SV. Ubiquitin-interacting motifs of ataxin-3 regulate its polyglutamine toxicity through Hsc70-4-dependent aggregation. eLife 2020; 9:60742. [PMID: 32955441 PMCID: PMC7505662 DOI: 10.7554/elife.60742] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 08/30/2020] [Indexed: 12/17/2022] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3) belongs to the family of polyglutamine neurodegenerations. Each disorder stems from the abnormal lengthening of a glutamine repeat in a different protein. Although caused by a similar mutation, polyglutamine disorders are distinct, implicating non-polyglutamine regions of disease proteins as regulators of pathogenesis. SCA3 is caused by polyglutamine expansion in ataxin-3. To determine the role of ataxin-3’s non-polyglutamine domains in disease, we utilized a new, allelic series of Drosophila melanogaster. We found that ataxin-3 pathogenicity is saliently controlled by polyglutamine-adjacent ubiquitin-interacting motifs (UIMs) that enhance aggregation and toxicity. UIMs function by interacting with the heat shock protein, Hsc70-4, whose reduction diminishes ataxin-3 toxicity in a UIM-dependent manner. Hsc70-4 also enhances pathogenicity of other polyglutamine proteins. Our studies provide a unique insight into the impact of ataxin-3 domains in SCA3, identify Hsc70-4 as a SCA3 enhancer, and indicate pleiotropic effects from HSP70 chaperones, which are generally thought to suppress polyglutamine degeneration.
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Affiliation(s)
- Sean L Johnson
- Department of Pharmacology, Wayne State University, Detroit, United States
| | - Bedri Ranxhi
- Department of Pharmacology, Wayne State University, Detroit, United States
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University, Detroit, United States
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University, Detroit, United States
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University, Detroit, United States.,Department of Neurology, Wayne State University, Detroit, United States
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21
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Abstract
PURPOSE OF REVIEW Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is a fatal, dominantly inherited, neurodegenerative disease caused by expansion of a CAG repeat in the coding region of the ATXN3 gene. No disease-modifying treatment is yet available for MJD/SCA3. This review discusses recently developed therapeutic strategies that hold promise as future effective treatments for this incurable disease. RECENT FINDINGS As a result of the exploration of multiple therapeutic approaches over the last decade, the MJD/SCA3 field is finally starting to see options for disease-modifying treatments for this disease come into view on the horizon. Recently developed strategies include DNA-targeted and RNA-targeted therapies, and approaches targeting protein quality control pathways and cellular homeostasis. SUMMARY While still in preclinical testing stages, antisense oligonucleotides, short hairpin RNAs and citalopram all show promise to reaching testing in clinical trials for MJD/SCA3. Two pharmacological approaches in early stages of development, the slipped-CAG DNA binding compound naphthyridine-azaquinolone and autophagosome-tethering compounds, also show potential therapeutic capacity for MJD/SCA3. Overall, a handful of therapeutic options are currently showing potential as future successful treatments for fatal MJD/SCA3.
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Affiliation(s)
- Maria do Carmo Costa
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, USA
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22
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Blount JR, Johnson SL, Libohova K, Todi SV, Tsou WL. Degron capability of the hydrophobic C-terminus of the polyglutamine disease protein, ataxin-3. J Neurosci Res 2020; 98:2096-2108. [PMID: 32643791 DOI: 10.1002/jnr.24684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 05/27/2020] [Accepted: 06/08/2020] [Indexed: 11/12/2022]
Abstract
Ataxin-3 is a deubiquitinase and polyglutamine disease protein whose cellular properties and functions are not entirely understood. Mutations in ataxin-3 cause spinocerebellar ataxia type 3 (SCA3), a neurodegenerative disorder that is a member of the polyglutamine family of diseases. Two major isoforms arise from alternative splicing of ATXN3 and are differently toxic in vivo as a result of faster proteasomal degradation of one isoform compared to the other. The isoforms vary only at their C-termini, suggesting that the hydrophobic C-terminus of the more quickly degraded form of ataxin-3 (here referred to as isoform 2) functions as a degron-that is, a peptide sequence that expedites the degradation of its host protein. We explored this notion in this study and present evidence that: (a) the C-terminus of ataxin-3 isoform 2 signals its degradation in a proteasome-dependent manner, (b) this effect from the C-terminus of isoform 2 does not require the ubiquitination of ataxin-3, and (c) the isolated C-terminus of isoform 2 can enhance the degradation of an unrelated protein. According to our data, the C-terminus of ataxin-3 isoform 2 is a degron, increasing overall understanding of the cellular properties of the SCA3 protein.
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Affiliation(s)
- Jessica R Blount
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Sean L Johnson
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA.,Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
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23
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Gadhave K, Kumar P, Kapuganti SK, Uversky VN, Giri R. Unstructured Biology of Proteins from Ubiquitin-Proteasome System: Roles in Cancer and Neurodegenerative Diseases. Biomolecules 2020; 10:E796. [PMID: 32455657 PMCID: PMC7278180 DOI: 10.3390/biom10050796] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/17/2020] [Accepted: 05/19/2020] [Indexed: 12/14/2022] Open
Abstract
The 26S proteasome is a large (~2.5 MDa) protein complex consisting of at least 33 different subunits and many other components, which form the ubiquitin proteasomal system (UPS), an ATP-dependent protein degradation system in the cell. UPS serves as an essential component of the cellular protein surveillance machinery, and its dysfunction leads to cancer, neurodegenerative and immunological disorders. Importantly, the functions and regulations of proteins are governed by the combination of ordered regions, intrinsically disordered protein regions (IDPRs) and molecular recognition features (MoRFs). The structure-function relationships of UPS components have not been identified completely; therefore, in this study, we have carried out the functional intrinsic disorder and MoRF analysis for potential neurodegenerative disease and anti-cancer targets of this pathway. Our report represents the presence of significant intrinsic disorder and disorder-based binding regions in several UPS proteins, such as extraproteasomal polyubiquitin receptors (UBQLN1 and UBQLN2), proteasome-associated polyubiquitin receptors (ADRM1 and PSMD4), deubiquitinating enzymes (DUBs) (ATXN3 and USP14), and ubiquitinating enzymes (E2 (UBE2R2) and E3 (STUB1) enzyme). We believe this study will have implications for the conformation-specific roles of different regions of these proteins. This will lead to a better understanding of the molecular basis of UPS-associated diseases.
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Affiliation(s)
- Kundlik Gadhave
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh 175005, India; (K.G.); (P.K.); (S.K.K.)
| | - Prateek Kumar
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh 175005, India; (K.G.); (P.K.); (S.K.K.)
| | - Shivani K. Kapuganti
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh 175005, India; (K.G.); (P.K.); (S.K.K.)
| | - Vladimir N. Uversky
- Department of Molecular Medicine and Byrd Alzheimer’s Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33620, USA;
- Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center “Pushchino Cientific Center for Biological Research of the Russian Academy of Sciences”, Pushchino, 142290 Moscow, Russia
| | - Rajanish Giri
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Himachal Pradesh 175005, India; (K.G.); (P.K.); (S.K.K.)
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24
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La Rosa P, Petrillo S, Bertini ES, Piemonte F. Oxidative Stress in DNA Repeat Expansion Disorders: A Focus on NRF2 Signaling Involvement. Biomolecules 2020; 10:biom10050702. [PMID: 32369911 PMCID: PMC7277112 DOI: 10.3390/biom10050702] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/13/2022] Open
Abstract
DNA repeat expansion disorders are a group of neuromuscular and neurodegenerative diseases that arise from the inheritance of long tracts of nucleotide repetitions, located in the regulatory region, introns, or inside the coding sequence of a gene. Although loss of protein expression and/or the gain of function of its transcribed mRNA or translated product represent the major pathogenic effect of these pathologies, mitochondrial dysfunction and imbalance in redox homeostasis are reported as common features in these disorders, deeply affecting their severity and progression. In this review, we examine the role that the redox imbalance plays in the pathological mechanisms of DNA expansion disorders and the recent advances on antioxidant treatments, particularly focusing on the expression and the activity of the transcription factor NRF2, the main cellular regulator of the antioxidant response.
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25
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Dantuma NP, Herzog LK. Machado-Joseph Disease: A Stress Combating Deubiquitylating Enzyme Changing Sides. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1233:237-260. [PMID: 32274760 DOI: 10.1007/978-3-030-38266-7_10] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Machado-Joseph disease (MJD), also known as Spinocerebellar ataxia type 3 (SCA3), is an autosomal dominant inheritable neurodegenerative disorder. After a long pre-symptomatic period, this late-onset disease progressively disables patients and typically leads to premature death. Neuronal loss in specific regions of the cerebellum, brainstem and basal ganglia as well as the spinal cord explains the spectra of debilitating neurological symptoms, most strikingly progressive limb, and gait ataxia. The genetic cause of MJD is a polyglutamine (polyQ) repeat expansion in the gene that encodes ataxin-3. This polyQ-containing protein displays a well-defined catalytic activity as ataxin-3 is a deubiquitylating enzyme that removes and disassembles ubiquitin chains from specific substrates. While mutant ataxin-3 with an expanded polyQ repeat induces cellular stress due to its propensity to aggregate, the native functions of wild-type ataxin-3 are linked to the cellular countermeasures against the very same stress conditions inflicted by polyQ-containing and other aggregation-prone proteins. Hence, a mixture of gain-of-function and loss-of-function mechanisms are likely to contribute to the neuronal demise observed in MJD. In this review, we discuss the intimate link between ataxin-3 and cellular stress and its relevance for therapeutic intervention in MJD.
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Affiliation(s)
- Nico P Dantuma
- Department of Cell and Molecular Biology (CMB), Karolinska Institutet, Stockholm, Sweden.
| | - Laura K Herzog
- Department of Cell and Molecular Biology (CMB), Karolinska Institutet, Stockholm, Sweden
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26
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Ashraf NS, Sutton JR, Yang Y, Ranxhi B, Libohova K, Shaw ED, Barget AJ, Todi SV, Paulson HL, Costa MDC. Druggable genome screen identifies new regulators of the abundance and toxicity of ATXN3, the Spinocerebellar Ataxia type 3 disease protein. Neurobiol Dis 2019; 137:104697. [PMID: 31783119 DOI: 10.1016/j.nbd.2019.104697] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 11/03/2019] [Accepted: 11/24/2019] [Indexed: 12/21/2022] Open
Abstract
Spinocerebellar Ataxia type 3 (SCA3, also known as Machado-Joseph disease) is a neurodegenerative disorder caused by a CAG repeat expansion encoding an abnormally long polyglutamine (polyQ) tract in the disease protein, ataxin-3 (ATXN3). No preventive treatment is yet available for SCA3. Because SCA3 is likely caused by a toxic gain of ATXN3 function, a rational therapeutic strategy is to reduce mutant ATXN3 levels by targeting pathways that control its production or stability. Here, we sought to identify genes that modulate ATXN3 levels as potential therapeutic targets in this fatal disorder. We screened a collection of siRNAs targeting 2742 druggable human genes using a cell-based assay based on luminescence readout of polyQ-expanded ATXN3. From 317 candidate genes identified in the primary screen, 100 genes were selected for validation. Among the 33 genes confirmed in secondary assays, 15 were validated in an independent cell model as modulators of pathogenic ATXN3 protein levels. Ten of these genes were then assessed in a Drosophila model of SCA3, and one was confirmed as a key modulator of physiological ATXN3 abundance in SCA3 neuronal progenitor cells. Among the 15 genes shown to modulate ATXN3 in mammalian cells, orthologs of CHD4, FBXL3, HR and MC3R regulate mutant ATXN3-mediated toxicity in fly eyes. Further mechanistic studies of one of these genes, FBXL3, encoding a F-box protein that is a component of the SKP1-Cullin-F-box (SCF) ubiquitin ligase complex, showed that it reduces levels of normal and pathogenic ATXN3 in SCA3 neuronal progenitor cells, primarily via a SCF complex-dependent manner. Bioinformatic analysis of the 15 genes revealed a potential molecular network with connections to tumor necrosis factor-α/nuclear factor-kappa B (TNF/NF-kB) and extracellular signal-regulated kinases 1 and 2 (ERK1/2) pathways. Overall, we identified 15 druggable genes with diverse functions to be suppressors or enhancers of pathogenic ATXN3 abundance. Among identified pathways highlighted by this screen, the FBXL3/SCF axis represents a novel molecular pathway that regulates physiological levels of ATXN3 protein.
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Affiliation(s)
- Naila S Ashraf
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Joanna R Sutton
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Yemen Yang
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Bedri Ranxhi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Emily D Shaw
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Anna J Barget
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA; Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Henry L Paulson
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.
| | - Maria do Carmo Costa
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.
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27
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Nóbrega C, Mendonça L, Marcelo A, Lamazière A, Tomé S, Despres G, Matos CA, Mechmet F, Langui D, den Dunnen W, de Almeida LP, Cartier N, Alves S. Restoring brain cholesterol turnover improves autophagy and has therapeutic potential in mouse models of spinocerebellar ataxia. Acta Neuropathol 2019; 138:837-858. [PMID: 31197505 DOI: 10.1007/s00401-019-02019-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 04/04/2019] [Accepted: 04/20/2019] [Indexed: 12/31/2022]
Abstract
Spinocerebellar ataxias (SCAs) are devastating neurodegenerative disorders for which no curative or preventive therapies are available. Deregulation of brain cholesterol metabolism and impaired brain cholesterol turnover have been associated with several neurodegenerative diseases. SCA3 or Machado-Joseph disease (MJD) is the most prevalent ataxia worldwide. We show that cholesterol 24-hydroxylase (CYP46A1), the key enzyme allowing efflux of brain cholesterol and activating brain cholesterol turnover, is decreased in cerebellar extracts from SCA3 patients and SCA3 mice. We investigated whether reinstating CYP46A1 expression would improve the disease phenotype of SCA3 mouse models. We show that administration of adeno-associated viral vectors encoding CYP46A1 to a lentiviral-based SCA3 mouse model reduces mutant ataxin-3 accumulation, which is a hallmark of SCA3, and preserves neuronal markers. In a transgenic SCA3 model with a severe motor phenotype we confirm that cerebellar delivery of AAVrh10-CYP46A1 is strongly neuroprotective in adult mice with established pathology. CYP46A1 significantly decreases ataxin-3 protein aggregation, alleviates motor impairments and improves SCA3-associated neuropathology. In particular, improvement in Purkinje cell number and reduction of cerebellar atrophy are observed in AAVrh10-CYP46A1-treated mice. Conversely, we show that knocking-down CYP46A1 in normal mouse brain impairs cholesterol metabolism, induces motor deficits and produces strong neurodegeneration with impairment of the endosomal-lysosomal pathway, a phenotype closely resembling that of SCA3. Remarkably, we demonstrate for the first time both in vitro, in a SCA3 cellular model, and in vivo, in mouse brain, that CYP46A1 activates autophagy, which is impaired in SCA3, leading to decreased mutant ataxin-3 deposition. More broadly, we show that the beneficial effect of CYP46A1 is also observed with mutant ataxin-2 aggregates. Altogether, our results confirm a pivotal role for CYP46A1 and brain cholesterol metabolism in neuronal function, pointing to a key contribution of the neuronal cholesterol pathway in mechanisms mediating clearance of aggregate-prone proteins. This study identifies CYP46A1 as a relevant therapeutic target not only for SCA3 but also for other SCAs.
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Affiliation(s)
- Clévio Nóbrega
- Department of Biomedical Sciences and Medicine, University of Algarve, Faro, Portugal
- Centre for Biomedical Research, University of Algarve, Faro, Portugal
- Algarve Biomedical Center, University of Algarve, Faro, Portugal
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Liliana Mendonça
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Adriana Marcelo
- Department of Biomedical Sciences and Medicine, University of Algarve, Faro, Portugal
- Centre for Biomedical Research, University of Algarve, Faro, Portugal
| | - Antonin Lamazière
- INSERM, Saint-Antoine Research Center, Sorbonne Université, Faculté de Médecine, AP-HP, Hôpital Saint Antoine, Département PM2, Paris, France
| | - Sandra Tomé
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Gaetan Despres
- INSERM, Saint-Antoine Research Center, Sorbonne Université, Faculté de Médecine, AP-HP, Hôpital Saint Antoine, Département PM2, Paris, France
| | - Carlos A Matos
- Department of Biomedical Sciences and Medicine, University of Algarve, Faro, Portugal
- Centre for Biomedical Research, University of Algarve, Faro, Portugal
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Fatich Mechmet
- Department of Biomedical Sciences and Medicine, University of Algarve, Faro, Portugal
- Centre for Biomedical Research, University of Algarve, Faro, Portugal
| | - Dominique Langui
- Institut du Cerveau et de la Moelle épinière, ICM, INSERM U1127, CNRS UMR7225, Sorbonne Université, Hôpital Pitié-Salpêtrière, 47 bd de l'Hôpital, 75013, Paris, France
| | - Wilfred den Dunnen
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, PO Box 30.001, 9700 RB, Groningen, The Netherlands
| | - Luis Pereira de Almeida
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
- Faculty of Pharmacy, University of Coimbra, 3000-548, Coimbra, Portugal.
| | - Nathalie Cartier
- INSERM U1169 92265 Fontenay aux Roses and Université Paris-Sud, Université Paris Saclay, 91400, Orsay, France.
- INSERM U1127, Institut du Cerveau et de la Moelle épinière (ICM), Hôpital Pitié-Salpêtrière, 47 bd de l'hôpital, 75013, Paris, France.
| | - Sandro Alves
- Brainvectis, Institut du Cerveau et de la Moelle épinière (ICM), Hôpital Pitié-Salpêtrière, 47 boulevard de l'Hôpital Paris, 75646, Paris, CEDEX 13, France.
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28
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Da Silva JD, Teixeira-Castro A, Maciel P. From Pathogenesis to Novel Therapeutics for Spinocerebellar Ataxia Type 3: Evading Potholes on the Way to Translation. Neurotherapeutics 2019; 16:1009-1031. [PMID: 31691128 PMCID: PMC6985322 DOI: 10.1007/s13311-019-00798-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is a neurodegenerative disorder caused by a polyglutamine expansion in the ATXN3 gene. In spite of the identification of a clear monogenic cause 25 years ago, the pathological process still puzzles researchers, impairing prospects for an effective therapy. Here, we propose the disruption of protein homeostasis as the hub of SCA3 pathogenesis, being the molecular mechanisms and cellular pathways that are deregulated in SCA3 downstream consequences of the misfolding and aggregation of ATXN3. Moreover, we attempt to provide a realistic perspective on how the translational/clinical research in SCA3 should evolve. This was based on molecular findings, clinical and epidemiological characteristics, studies of proposed treatments in other conditions, and how that information is essential for their (re-)application in SCA3. This review thus aims i) to critically evaluate the current state of research on SCA3, from fundamental to translational and clinical perspectives; ii) to bring up the current key questions that remain unanswered in this disorder; and iii) to provide a frame on how those answers should be pursued.
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Affiliation(s)
- Jorge Diogo Da Silva
- 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
| | - 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.
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29
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Johnson SL, Blount JR, Libohova K, Ranxhi B, Paulson HL, Tsou WL, Todi SV. Differential toxicity of ataxin-3 isoforms in Drosophila models of Spinocerebellar Ataxia Type 3. Neurobiol Dis 2019; 132:104535. [PMID: 31310802 DOI: 10.1016/j.nbd.2019.104535] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/05/2019] [Accepted: 07/12/2019] [Indexed: 12/28/2022] Open
Abstract
The most commonly inherited dominant ataxia, Spinocerebellar Ataxia Type 3 (SCA3), is caused by a CAG repeat expansion that encodes an abnormally long polyglutamine (polyQ) repeat in the disease protein ataxin-3, a deubiquitinase. Two major full-length isoforms of ataxin-3 exist, both of which contain the same N-terminal portion and polyQ repeat, but differ in their C-termini; one (denoted here as isoform 1) contains a motif that binds ataxin-3's substrate, ubiquitin, whereas the other (denoted here as isoform 2) has a hydrophobic tail. Most SCA3 studies have focused on isoform 1, the predominant version in mammalian brain, yet both isoforms are present in brain and a better understanding of their relative pathogenicity in vivo is needed. We took advantage of the fruit fly, Drosophila melanogaster to model SCA3 and to examine the toxicity of each ataxin-3 isoform. Our assays reveal isoform 1 to be markedly more toxic than isoform 2 in all fly tissues. Reduced toxicity from isoform 2 is due to much lower protein levels as a result of its expedited degradation. Additional studies indicate that isoform 1 is more aggregation-prone than isoform 2 and that the C-terminus of isoform 2 is critical for its enhanced proteasomal degradation. According to our results, although both full-length, pathogenic ataxin-3 isoforms are toxic, isoform 1 is likely the primary contributor to SCA3 due to its presence at higher levels. Isoform 2, as a result of rapid degradation that is dictated by its tail, is unlikely to be a key player in this disease. Our findings provide new insight into the biology of this ataxia and the cellular processing of the underlying disease protein.
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Affiliation(s)
- Sean L Johnson
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Jessica R Blount
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Bedri Ranxhi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Henry L Paulson
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA.
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA; Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA.
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30
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Non-Proteasomal UbL-UbA Family of Proteins in Neurodegeneration. Int J Mol Sci 2019; 20:ijms20081893. [PMID: 30999567 PMCID: PMC6514573 DOI: 10.3390/ijms20081893] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 04/09/2019] [Accepted: 04/15/2019] [Indexed: 12/11/2022] Open
Abstract
Ubiquitin-like/ubiquitin-associated proteins (UbL-UbA) are a well-studied family of non-proteasomal ubiquitin receptors that are evolutionarily conserved across species. Members of this non-homogenous family facilitate and support proteasomal activity by promoting different effects on proteostasis but exhibit diverse extra-proteasomal activities. Dysfunctional UbL-UbA proteins render cells, particularly neurons, more susceptible to stressors or aging and may cause earlier neurodegeneration. In this review, we summarized the properties and functions of UbL-UbA family members identified to date, with an emphasis on new findings obtained using Drosophila models showing a direct or indirect role in some neurodegenerative diseases.
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31
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Mancini A, Vitucci D, Randers MB, Schmidt JF, Hagman M, Andersen TR, Imperlini E, Mandola A, Orrù S, Krustrup P, Buono P. Lifelong Football Training: Effects on Autophagy and Healthy Longevity Promotion. Front Physiol 2019; 10:132. [PMID: 30837897 PMCID: PMC6390296 DOI: 10.3389/fphys.2019.00132] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 02/04/2019] [Indexed: 12/30/2022] Open
Abstract
Aging is a physiological process characterized by a progressive decline of biological functions and an increase in destructive processes in cells and organs. Physical activity and exercise positively affects the expression of skeletal muscle markers involved in longevity pathways. Recently, a new mechanism, autophagy, was introduced to the adaptations induced by acute and chronic exercise as responsible of positive metabolic modification and health-longevity promotion. However, the molecular mechanisms regulating autophagy in response to physical activity and exercise are sparsely described. We investigated the long-term adaptations resulting from lifelong recreational football training on the expression of skeletal muscle markers involved in autophagy signaling. We demonstrated that lifelong football training increased the expression of messengers: RAD23A, HSPB6, RAB1B, TRAP1, SIRT2, and HSBPB1, involved in the auto-lysosomal and proteasome-mediated protein degradation machinery; of RPL1, RPL4, RPL36, MRLP37, involved in cellular growth and differentiation processes; of the Bcl-2, HSP70, HSP90, PSMD13, and of the ATG5-ATG12 protein complex, involved in proteasome promotion and autophagy processes in muscle samples from lifelong trained subjects compared to age-matched untrained controls. In conclusion, our results indicated that lifelong football training positively influence exercise-induced autophagy processes and protein quality control in skeletal muscle, thus promoting healthy aging.
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Affiliation(s)
- Annamaria Mancini
- Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli Parthenope, Naples, Italy.,CEINGE-Biotecnologie Avanzate, Naples, Italy
| | | | - Morten Bredsgaard Randers
- Department of Sports and Clinical Biomechanics, Sport and Health Sciences Cluster, University of Southern Denmark, Odense, Denmark
| | - Jakob Friis Schmidt
- Copenhagen Centre for Team Sport and Health, Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Marie Hagman
- Department of Sports and Clinical Biomechanics, Sport and Health Sciences Cluster, University of Southern Denmark, Odense, Denmark
| | - Thomas Rostgaard Andersen
- Department of Sports and Clinical Biomechanics, Sport and Health Sciences Cluster, University of Southern Denmark, Odense, Denmark
| | | | - Annalisa Mandola
- Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli Parthenope, Naples, Italy.,CEINGE-Biotecnologie Avanzate, Naples, Italy
| | - Stefania Orrù
- Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli Parthenope, Naples, Italy.,IRCCS SDN, Naples, Italy
| | - Peter Krustrup
- Department of Sports and Clinical Biomechanics, Sport and Health Sciences Cluster, University of Southern Denmark, Odense, Denmark.,Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Pasqualina Buono
- Dipartimento di Scienze Motorie e del Benessere, Università degli Studi di Napoli Parthenope, Naples, Italy.,CEINGE-Biotecnologie Avanzate, Naples, Italy.,IRCCS SDN, Naples, Italy
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32
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Weishäupl D, Schneider J, Peixoto Pinheiro B, Ruess C, Dold SM, von Zweydorf F, Gloeckner CJ, Schmidt J, Riess O, Schmidt T. Physiological and pathophysiological characteristics of ataxin-3 isoforms. J Biol Chem 2018; 294:644-661. [PMID: 30455355 DOI: 10.1074/jbc.ra118.005801] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/08/2018] [Indexed: 12/18/2022] Open
Abstract
Ataxin-3 is a deubiquitinating enzyme and the affected protein in the neurodegenerative disorder Machado-Joseph disease (MJD). The ATXN3 gene is alternatively spliced, resulting in protein isoforms that differ in the number of ubiquitin-interacting motifs. Additionally, nonsynonymous SNPs in ATXN3 cause amino acid changes in ataxin-3, and one of these polymorphisms introduces a premature stop codon in one isoform. Here, we examined the effects of different ataxin-3 isoforms and of the premature stop codon on ataxin-3's physiological function and on main disease mechanisms. At the physiological level, we show that alternative splicing and the premature stop codon alter ataxin-3 stability and that ataxin-3 isoforms differ in their enzymatic deubiquitination activity, subcellular distribution, and interaction with other proteins. At the pathological level, we found that the expansion of the polyglutamine repeat leads to a stabilization of ataxin-3 and that ataxin-3 isoforms differ in their aggregation properties. Interestingly, we observed a functional interaction between normal and polyglutamine-expanded ATXN3 allelic variants. We found that interactions between different ATXN3 allelic variants modify the physiological and pathophysiological properties of ataxin-3. Our findings indicate that alternative splicing and interactions between different ataxin-3 isoforms affect not only major aspects of ataxin-3 function but also MJD pathogenesis. Our results stress the importance of considering isoforms of disease-causing proteins and their interplay with the normal allelic variant as disease modifiers in MJD and autosomal-dominantly inherited diseases in general.
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Affiliation(s)
- Daniel Weishäupl
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany.,the Graduate Training Center of Neuroscience, 72074 Tübingen, Germany
| | - Juliane Schneider
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Barbara Peixoto Pinheiro
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Corinna Ruess
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Sandra Maria Dold
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Felix von Zweydorf
- the German Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany, and
| | - Christian Johannes Gloeckner
- the German Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany, and.,the Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, 72076 Tübingen, Germany
| | - Jana Schmidt
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Olaf Riess
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany.,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
| | - Thorsten Schmidt
- From the Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany, .,the Center for Rare Diseases, 72076 Tübingen, Germany.,the NGS Competence Center, 72076 Tübingen, Germany
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33
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Wan L, Xu K, Chen Z, Tang B, Jiang H. Roles of Post-translational Modifications in Spinocerebellar Ataxias. Front Cell Neurosci 2018; 12:290. [PMID: 30283301 PMCID: PMC6156280 DOI: 10.3389/fncel.2018.00290] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 08/13/2018] [Indexed: 12/17/2022] Open
Abstract
Post-translational modifications (PTMs), including phosphorylation, acetylation, ubiquitination, SUMOylation, etc., of proteins can modulate protein properties such as intracellular distribution, activity, stability, aggregation, and interactions. Therefore, PTMs are vital regulatory mechanisms for multiple cellular processes. Spinocerebellar ataxias (SCAs) are hereditary, heterogeneous, neurodegenerative diseases for which the primary manifestation involves ataxia. Because the pathogenesis of most SCAs is correlated with mutant proteins directly or indirectly, the PTMs of disease-related proteins might functionally affect SCA development and represent potential therapeutic interventions. Here, we review multiple PTMs related to disease-causing proteins in SCAs pathogenesis and their effects. Furthermore, we discuss these PTMs as potential targets for treating SCAs and describe translational therapies targeting PTMs that have been published.
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Affiliation(s)
- Linlin Wan
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Keqin Xu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Zhao Chen
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China
- Laboratory of Medical Genetics, Central South University, Changsha, China
- Parkinson’s Disease Center of Beijing Institute for Brain Disorders, Beijing, China
- Collaborative Innovation Center for Brain Science, Shanghai, China
- Collaborative Innovation Center for Genetics and Development, Shanghai, China
| | - Hong Jiang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Diseases, Central South University, Changsha, China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, China
- Laboratory of Medical Genetics, Central South University, Changsha, China
- Department of Neurology, Xinjiang Medical University, Ürümqi, China
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Ashraf NS, Duarte-Silva S, Shaw ED, Maciel P, Paulson HL, Teixeira-Castro A, Costa MDC. Citalopram Reduces Aggregation of ATXN3 in a YAC Transgenic Mouse Model of Machado-Joseph Disease. Mol Neurobiol 2018; 56:3690-3701. [PMID: 30187384 DOI: 10.1007/s12035-018-1331-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 08/22/2018] [Indexed: 01/20/2023]
Abstract
Machado-Joseph disease, also known as spinocerebellar ataxia type 3, is a fatal polyglutamine disease with no disease-modifying treatment. The selective serotonin reuptake inhibitor citalopram was shown in nematode and mouse models to be a compelling repurposing candidate for Machado-Joseph disease therapeutics. We sought to confirm the efficacy of citalopram to decrease ATXN3 aggregation in an unrelated mouse model of Machado-Joseph disease. Four-week-old YACMJD84.2 mice and non-transgenic littermates were given citalopram 8 mg/kg in drinking water or water for 10 weeks. At the end of treatment, brains were collected for biochemical and pathological analyses. Brains of citalopram-treated YACMJD84.2 mice showed an approximate 50% decrease in the percentage of cells containing ATXN3-positive inclusions in the substantia nigra and three examined brainstem nuclei compared to controls. No differences in ATXN3 inclusion load were observed in deep cerebellar nuclei of mice. Citalopram effect on ATXN3 aggregate burden was corroborated by immunoblotting analysis. While lysates from the brainstem and cervical spinal cord of citalopram-treated mice showed a decrease in all soluble forms of ATXN3 and a trend toward reduction of insoluble ATXN3, no differences in ATXN3 levels were found between cerebella of citalopram-treated and vehicle-treated mice. Citalopram treatment altered levels of select components of the cellular protein homeostatic machinery that may be expected to enhance the capacity to refold and/or degrade mutant ATXN3. The results here obtained in a second independent mouse model of Machado-Joseph disease further support citalopram as a potential drug to be repurposed for this fatal disorder.
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Affiliation(s)
- Naila S Ashraf
- Department of Neurology, Michigan Medicine, University of Michigan, A. Alfred Taubman Biomedical Sciences Research Building, 109 Zina Pitcher Place, Ann Arbor, MI, 48109-2200, USA
| | - Sara Duarte-Silva
- School of Medicine, University of Minho, Campus de Gualtar, Life and Health Sciences Research Institute (ICVS), Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Emily D Shaw
- Department of Neurology, Michigan Medicine, University of Michigan, A. Alfred Taubman Biomedical Sciences Research Building, 109 Zina Pitcher Place, Ann Arbor, MI, 48109-2200, USA
| | - Patrícia Maciel
- School of Medicine, University of Minho, Campus de Gualtar, Life and Health Sciences Research Institute (ICVS), Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Henry L Paulson
- Department of Neurology, Michigan Medicine, University of Michigan, A. Alfred Taubman Biomedical Sciences Research Building, 109 Zina Pitcher Place, Ann Arbor, MI, 48109-2200, USA
| | - Andreia Teixeira-Castro
- School of Medicine, University of Minho, Campus de Gualtar, Life and Health Sciences Research Institute (ICVS), Braga, Portugal. .,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal. .,Department of Molecular Biosciences, Northwestern University, Evanston, IL, 60208, USA.
| | - Maria do Carmo Costa
- Department of Neurology, Michigan Medicine, University of Michigan, A. Alfred Taubman Biomedical Sciences Research Building, 109 Zina Pitcher Place, Ann Arbor, MI, 48109-2200, USA.
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35
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Nath SR, Yu Z, Gipson TA, Marsh GB, Yoshidome E, Robins DM, Todi SV, Housman DE, Lieberman AP. Androgen receptor polyglutamine expansion drives age-dependent quality control defects and muscle dysfunction. J Clin Invest 2018; 128:3630-3641. [PMID: 29809168 DOI: 10.1172/jci99042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 05/24/2018] [Indexed: 12/28/2022] Open
Abstract
Skeletal muscle has emerged as a critical, disease-relevant target tissue in spinal and bulbar muscular atrophy, a degenerative disorder of the neuromuscular system caused by a CAG/polyglutamine (polyQ) expansion in the androgen receptor (AR) gene. Here, we used RNA-sequencing (RNA-Seq) to identify pathways that are disrupted in diseased muscle using AR113Q knockin mice. This analysis unexpectedly identified substantially diminished expression of numerous ubiquitin/proteasome pathway genes in AR113Q muscle, encoding approximately 30% of proteasome subunits and 20% of E2 ubiquitin conjugases. These changes were age, hormone, and glutamine length dependent and arose due to a toxic gain of function conferred by the mutation. Moreover, altered gene expression was associated with decreased levels of the proteasome transcription factor NRF1 and its activator DDI2 and resulted in diminished proteasome activity. Ubiquitinated ADRM1 was detected in AR113Q muscle, indicating the occurrence of stalled proteasomes in mutant mice. Finally, diminished expression of Drosophila orthologues of NRF1 or ADRM1 promoted the accumulation of polyQ AR protein and increased toxicity. Collectively, these data indicate that AR113Q muscle develops progressive proteasome dysfunction that leads to the impairment of quality control and the accumulation of polyQ AR protein, key features that contribute to the age-dependent onset and progression of this disorder.
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Affiliation(s)
- Samir R Nath
- Department of Pathology.,Medical Scientist Training Program, and.,Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | | - Theresa A Gipson
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Gregory B Marsh
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | | | - Diane M Robins
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - David E Housman
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Blount JR, Libohova K, Marsh GB, Sutton JR, Todi SV. Expression and Regulation of Deubiquitinase-Resistant, Unanchored Ubiquitin Chains in Drosophila. Sci Rep 2018; 8:8513. [PMID: 29855490 PMCID: PMC5981470 DOI: 10.1038/s41598-018-26364-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 05/10/2018] [Indexed: 01/03/2023] Open
Abstract
The modifier protein, ubiquitin (Ub) regulates various cellular pathways by controlling the fate of substrates to which it is conjugated. Ub moieties are also conjugated to each other, forming chains of various topologies. In cells, poly-Ub is attached to proteins and also exists in unanchored form. Accumulation of unanchored poly-Ub is thought to be harmful and quickly dispersed through dismantling by deubiquitinases (DUBs). We wondered whether disassembly by DUBs is necessary to control unanchored Ub chains in vivo. We generated Drosophila melanogaster lines that express Ub chains non-cleavable into mono-Ub by DUBs. These chains are rapidly modified with different linkages and represent various types of unanchored species. We found that unanchored poly-Ub is not devastating in Drosophila, under normal conditions or during stress. The DUB-resistant, free Ub chains are degraded by the proteasome, at least in part through the assistance of VCP and its cofactor, p47. Also, unanchored poly-Ub that cannot be cleaved by DUBs can be conjugated en bloc, in vivo. Our results indicate that unanchored poly-Ub species need not be intrinsically toxic; they can be controlled independently of DUB-based disassembly by being degraded, or through conjugation onto other proteins.
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Affiliation(s)
- Jessica R Blount
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Gregory B Marsh
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Joanna R Sutton
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA. .,Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA.
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37
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Ristic G, Sutton JR, Libohova K, Todi SV. Toxicity and aggregation of the polyglutamine disease protein, ataxin-3 is regulated by its binding to VCP/p97 in Drosophila melanogaster. Neurobiol Dis 2018; 116:78-92. [PMID: 29704548 DOI: 10.1016/j.nbd.2018.04.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 03/26/2018] [Accepted: 04/22/2018] [Indexed: 01/01/2023] Open
Abstract
Among the nine dominantly inherited, age-dependent neurodegenerative diseases caused by abnormal expansion in the polyglutamine (polyQ) repeat of otherwise unrelated proteins is Spinocerebellar Ataxia Type 3 (SCA3). SCA3 is caused by polyQ expansion in the deubiquitinase (DUB), ataxin-3. Molecular sequelae related to SCA3 remain unclear. Here, we sought to understand the role of protein context in SCA3 by focusing on the interaction between this DUB and Valosin-Containing Protein (VCP). VCP is bound directly by ataxin-3 through an arginine-rich area preceding the polyQ repeat. We examined the importance of this interaction in ataxin-3-dependent degeneration in Drosophila melanogaster. Our assays with new isogenic fly lines expressing pathogenic ataxin-3 with an intact or mutated VCP-binding site show that disrupting the ataxin-3-VCP interaction delays the aggregation of the toxic protein in vivo. Importantly, early on flies that express pathogenic ataxin-3 with a mutated VCP-binding site are indistinguishable from flies that do not express any SCA3 protein. Also, reducing levels of VCP through RNA-interference has a similar, protective effect to mutating the VCP-binding site of pathogenic ataxin-3. Based on in vivo pulse-chases, aggregated species of ataxin-3 are highly stable, in a manner independent of VCP-binding. Collectively, our results highlight an important role for the ataxin-3-VCP interaction in SCA3, based on a model that posits a seeding effect from VCP on pathogenic ataxin-3 aggregation and subsequent toxicity.
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Affiliation(s)
- Gorica Ristic
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Joanna R Sutton
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI, USA; Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA.
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Abstract
Diseases such as Huntington's disease and certain spinocerebellar ataxias are caused by the expansion of genomic cytosine-adenine-guanine (CAG) trinucleotide repeats beyond a specific threshold. These diseases are all characterised by neurological symptoms and central neurodegeneration, but our understanding of how expanded repeats drive neuronal loss is incomplete. Recent human genetic evidence implicates DNA repair pathways, especially mismatch repair, in modifying the onset and progression of CAG repeat diseases. Repair pathways might operate directly on repeat sequences by licensing or inhibiting repeat expansion in neurons. Alternatively, or in addition, because many of the genes containing pathogenic CAG repeats encode proteins that themselves have roles in the DNA damage response, it is possible that repeat expansions impair specific DNA repair pathways. DNA damage could then accrue in neurons, leading to further expansion at repeat loci, thus setting up a vicious cycle of pathology. In this review, we consider DNA damage and repair pathways in postmitotic neurons in the context of disease-causing CAG repeats. Investigating and understanding these pathways, which are clearly relevant in promoting and ameliorating disease in humans, is a research priority, as they are known to modify disease and therefore constitute prevalidated drug targets.
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Affiliation(s)
- Thomas H Massey
- Institute of Psychological Medicine and Clinical Neurosciences, MRC Centre for Neuropsychiatric Genetics and Genomics, Hadyn Ellis Building, Cardiff University, Cardiff, CF24 4HQ, UK
| | - Lesley Jones
- Institute of Psychological Medicine and Clinical Neurosciences, MRC Centre for Neuropsychiatric Genetics and Genomics, Hadyn Ellis Building, Cardiff University, Cardiff, CF24 4HQ, UK
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Singh RK, Dagnino L. E2F1 interactions with hHR23A inhibit its degradation and promote DNA repair. Oncotarget 2018; 7:26275-92. [PMID: 27028861 PMCID: PMC5041980 DOI: 10.18632/oncotarget.8362] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 03/07/2016] [Indexed: 01/11/2023] Open
Abstract
Nucleotide excision repair (NER) is a major mechanism for removal of DNA lesions induced by exposure to UV radiation in the epidermis. Recognition of damaged DNA sites is the initial step in their repair, and requires multiprotein complexes that contain XPC and hHR23 proteins, or their orthologues. A variety of transcription factors are also involved in NER, including E2F1. In epidermal keratinocytes, UV exposure induces E2F1 phosphorylation, which allows it to recruit various NER factors to sites of DNA damage. However, the relationship between E2F1 and hHR23 proteins vis-à-vis NER has remained unexplored. We now show that E2F1 and hHR23 proteins can interact, and this interaction stabilizes E2F1, inhibiting its proteasomal degradation. Reciprocally, E2F1 regulates hHR23A subcellular localization, recruiting it to sites of DNA photodamage. As a result, E2F1 and hHR23A enhance DNA repair following exposure to UV radiation, contributing to genomic stability in the epidermis.
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Affiliation(s)
- Randeep K Singh
- Department of Physiology and Pharmacology, Children's Health Research Institute and Lawson Health Research Institute, The University of Western Ontario, London, Ontario, N6A 5C1, Canada
| | - Lina Dagnino
- Department of Physiology and Pharmacology, Children's Health Research Institute and Lawson Health Research Institute, The University of Western Ontario, London, Ontario, N6A 5C1, Canada
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40
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Yang H, Yue HW, He WT, Hong JY, Jiang LL, Hu HY. PolyQ-expanded huntingtin and ataxin-3 sequester ubiquitin adaptors hHR23B and UBQLN2 into aggregates via conjugated ubiquitin. FASEB J 2018; 32:2923-2933. [PMID: 29401586 DOI: 10.1096/fj.201700801rr] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The components of ubiquitin (Ub)-proteasome system, such as Ub, Ub adaptors, or proteasome subunits, are commonly accumulated with the aggregated proteins in inclusions, but how protein aggregates sequester Ub-related proteins remains elusive. Using N-terminal huntingtin (Htt-N552) and ataxin (Atx)-3 as model proteins, we investigated the molecular mechanism underlying sequestration of Ub adaptors by polyQ-expanded proteins. We found that polyQ-expanded Htt-N552 and Atx-3 sequester endogenous Ub adaptors, human RAD23 homolog B (hHR23B) and ubiquilin (UBQLN)-2, into inclusions. This sequestration effect is dependent on the UBA domains of Ub adaptors and the conjugated Ub of the aggregated proteins. Moreover, polyQ-expanded Htt-N552 and Atx-3 reduce the protein level of xeroderma pigmentosum group C (XPC) by sequestration of hHR23B, suggesting that this process may cut down the available quantity of hHR23B and thus affect its normal function in stabilizing XPC. Our findings demonstrate that polyQ-expanded proteins sequester Ub adaptors or other Ub-related proteins into aggregates or inclusions through ubiquitination of the pathogenic proteins. This study may also provide a common mechanism for the formation of Ub-positive inclusions in cells.-Yang, H., Yue, H.-W., He, W.-T., Hong, J.-Y., Jiang, L.-L., Hu, H.-Y. PolyQ-expanded huntingtin and ataxin-3 sequester ubiquitin adaptors hHR23B and UBQLN2 into aggregates via conjugated ubiquitin.
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Affiliation(s)
- Hui Yang
- State Key Laboratory of Molecular Biology, Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology (SIBCB), University of CAS, Shanghai, China.,State Key Laboratory of Genetic Engineering, School of Life Sciences, Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai, China
| | - Hong-Wei Yue
- State Key Laboratory of Molecular Biology, Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology (SIBCB), University of CAS, Shanghai, China
| | - Wen-Tian He
- State Key Laboratory of Molecular Biology, Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology (SIBCB), University of CAS, Shanghai, China
| | - Jun-Ye Hong
- State Key Laboratory of Molecular Biology, Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology (SIBCB), University of CAS, Shanghai, China
| | - Lei-Lei Jiang
- State Key Laboratory of Molecular Biology, Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology (SIBCB), University of CAS, Shanghai, China
| | - Hong-Yu Hu
- State Key Laboratory of Molecular Biology, Chinese Academy of Sciences (CAS) Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology (SIBCB), University of CAS, Shanghai, China
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Polyglutamine-Independent Features in Ataxin-3 Aggregation and Pathogenesis of Machado-Joseph Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1049:275-288. [PMID: 29427109 DOI: 10.1007/978-3-319-71779-1_14] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The expansion of a trinucleotide (CAG) repeat, translated into a polyglutamine expanded sequence in the protein encoded by the MJD gene, was identified over 20 years ago as the causative mutation in a severe neurodegenerative disorder originally diagnosed in individuals of Portuguese ancestry. This incapacitating disease, called Machado-Joseph disease or spinocebellar ataxia type 3, is integrated into a larger group of neurodegenerative disorders-the polyglutamine expansion disorders-caused by extension of a CAG repeat in the coding sequence of otherwise unrelated genes. These diseases are generally linked with the appearance of intracellular inclusions , which despite having a controversial role in disease appearance and development represent a characteristic common fingerprint in all polyglutamine-related disorders. Although polyglutamine expansion is an obvious trigger for neuronal dysfunction, the role of the different domains of these complex proteins in the function and aggregation properties of the carrier proteins is being uncovered in recent studies. In this review the current knowledge about the structural and functional features of full-length ataxin-3 protein will be discussed. The intrinsic conformational dynamics and interplay between the globular and intrinsically disordered regions of ataxin-3 will be highlighted, and a perspective picture of the role of known ataxin-3 post-translational modifications on regulating ataxin-3 aggregation and function will be drawn.
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Costa MDC, Ashraf NS, Fischer S, Yang Y, Schapka E, Joshi G, McQuade TJ, Dharia RM, Dulchavsky M, Ouyang M, Cook D, Sun D, Larsen MJ, Gestwicki JE, Todi SV, Ivanova MI, Paulson HL. Unbiased screen identifies aripiprazole as a modulator of abundance of the polyglutamine disease protein, ataxin-3. Brain 2017; 139:2891-2908. [PMID: 27645800 DOI: 10.1093/brain/aww228] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 07/24/2016] [Indexed: 11/14/2022] Open
Abstract
No disease-modifying treatment exists for the fatal neurodegenerative polyglutamine disease known both as Machado-Joseph disease and spinocerebellar ataxia type 3. As a potential route to therapy, we identified small molecules that reduce levels of the mutant disease protein, ATXN3. Screens of a small molecule collection, including 1250 Food and Drug Administration-approved drugs, in a novel cell-based assay, followed by secondary screens in brain slice cultures from transgenic mice expressing the human disease gene, identified the atypical antipsychotic aripiprazole as one of the hits. Aripiprazole increased longevity in a Drosophila model of Machado-Joseph disease and effectively reduced aggregated ATXN3 species in flies and in brains of transgenic mice treated for 10 days. The aripiprazole-mediated decrease in ATXN3 abundance may reflect a complex response culminating in the modulation of specific components of cellular protein homeostasis. Aripiprazole represents a potentially promising therapeutic drug for Machado-Joseph disease and possibly other neurological proteinopathies.
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Affiliation(s)
| | - Naila S Ashraf
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Svetlana Fischer
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Yemen Yang
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Emily Schapka
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Gnanada Joshi
- Department of Pharmacology, Wayne State University, Detroit, MI, USA
| | - Thomas J McQuade
- Center for Chemical Genomics, Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Rahil M Dharia
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Mark Dulchavsky
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Michelle Ouyang
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - David Cook
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Duxin Sun
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | - Martha J Larsen
- Center for Chemical Genomics, Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Jason E Gestwicki
- Department of Pharmaceutical Chemistry, Institute for Neurodegenerative Diseases, University of California at San Francisco, San Francisco, CA, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University, Detroit, MI, USA.,Department of Neurology, Wayne State University, Detroit, MI, USA
| | - Magdalena I Ivanova
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.,Department of Biophysics, University of Michigan, Ann Arbor, MI, USA
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
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43
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Polyglutamine expansion diseases: More than simple repeats. J Struct Biol 2017; 201:139-154. [PMID: 28928079 DOI: 10.1016/j.jsb.2017.09.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 08/24/2017] [Accepted: 09/15/2017] [Indexed: 12/27/2022]
Abstract
Polyglutamine (polyQ) repeat-containing proteins are widespread in the human proteome but only nine of them are associated with highly incapacitating neurodegenerative disorders. The genetic expansion of the polyQ tract in disease-related proteins triggers a series of events resulting in neurodegeneration. The polyQ tract plays the leading role in the aggregation mechanism, but other elements modulate the aggregation propensity in the context of the full-length proteins, as implied by variations in the length of the polyQ tract required to trigger the onset of a given polyQ disease. Intrinsic features such as the presence of aggregation-prone regions (APRs) outside the polyQ segments and polyQ-flanking sequences, which synergistically participate in the aggregation process, are emerging for several disease-related proteins. The inherent polymorphic structure of polyQ stretches places the polyQ proteins in a central position in protein-protein interaction networks, where interacting partners may additionally shield APRs or reshape the aggregation course. Expansion of the polyQ tract perturbs the cellular homeostasis and contributes to neuronal failure by modulating protein-protein interactions and enhancing toxic oligomerization. Post-translational modifications further regulate self-assembly either by directly altering the intrinsic aggregation propensity of polyQ proteins, by modulating their interaction with different macromolecules or by modifying their withdrawal by the cell quality control machinery. Here we review the recent data on the multifaceted aggregation pathways of disease-related polyQ proteins, focusing on ataxin-3, the protein mutated in Machado-Joseph disease. Further mechanistic understanding of this network of events is crucial for the development of effective therapies for polyQ diseases.
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Abstract
The dominantly inherited spinocerebellar ataxias (SCAs) are a large and diverse group of neurodegenerative diseases. The most prevalent SCAs (SCA1, SCA2, SCA3, SCA6 and SCA7) are caused by expansion of a glutamine-encoding CAG repeat in the affected gene. These SCAs represent a substantial portion of the polyglutamine neurodegenerative disorders and provide insight into this class of diseases as a whole. Recent years have seen considerable progress in deciphering the clinical, pathological, physiological and molecular aspects of the polyglutamine SCAs, with these advances establishing a solid base from which to pursue potential therapeutic approaches.
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45
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Saeki Y. Ubiquitin recognition by the proteasome. J Biochem 2017; 161:113-124. [PMID: 28069863 DOI: 10.1093/jb/mvw091] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 11/21/2016] [Indexed: 12/14/2022] Open
Abstract
The 26S proteasome is a 2.5-MDa complex responsible for the selective, ATP-dependent degradation of ubiquitylated proteins in eukaryotic cells. Substrates in hundreds cellular pathways are timely ubiquitylated and converged to the proteasome by direct recognition or by multiple shuttle factors. Engagement of substrate protein triggers conformational changes of the proteasome, which drive substrate unfolding, deubiquitylation and translocation of substrates to proteolytic sites. Recent studies have challenged the previous paradigm that Lys48-linked tetraubiquitin is a minimal degradation signal: in addition, monoubiquitylation or multiple short ubiquitylations can serve as the targeting signal for proteasomal degradation. In this review, I highlight recent advances in our understanding of the proteasome structure, the ubiquitin topology in proteasome targeting, and the cellular factors that regulate proteasomal degradation.
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Affiliation(s)
- Yasushi Saeki
- Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
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Das B, Rajagopalan S, Joshi GS, Xu L, Luo D, Andersen JK, Todi SV, Dutta AK. A novel iron (II) preferring dopamine agonist chelator D-607 significantly suppresses α-syn- and MPTP-induced toxicities in vivo. Neuropharmacology 2017; 123:88-99. [PMID: 28533164 DOI: 10.1016/j.neuropharm.2017.05.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 05/17/2017] [Accepted: 05/18/2017] [Indexed: 12/28/2022]
Abstract
Here, we report the characterization of a novel hybrid D2/D3 agonist and iron (II) specific chelator, D-607, as a multi-target-directed ligand against Parkinson's disease (PD). In our previously published report, we showed that D-607 is a potent agonist of dopamine (DA) D2/D3 receptors, exhibits efficacy in a reserpinized PD animal model and preferentially chelates to iron (II). As further evidence of its potential as a neuroprotective agent in PD, the present study reveals D-607 to be protective in neuronal PC12 cells against 6-OHDA toxicity. In an in vivo Drosophila melanogaster model expressing a disease-causing variant of α-synuclein (α-Syn) protein in fly eyes, the compound was found to significantly suppress toxicity compared to controls, concomitant with reduced levels of aggregated α-Syn. Furthermore, D-607 was able to rescue DAergic neurons from MPTP toxicity in mice, a well-known PD neurotoxicity model, following both sub-chronic and chronic MPTP administration. Mechanistic studies indicated that possible protection of mitochondria, up-regulation of hypoxia-inducible factor, reduction in formation of α-Syn aggregates and antioxidant activity may underlie the observed neuroprotection effects. These observations strongly suggest that D-607 has potential as a promising multifunctional lead molecule for viable symptomatic and disease-modifying therapy for PD.
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Affiliation(s)
- Banibrata Das
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48202, USA
| | | | - Gnanada S Joshi
- Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA
| | - Liping Xu
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Dan Luo
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Julie K Andersen
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA
| | - Aloke K Dutta
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48202, USA.
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Sutton JR, Blount JR, Libohova K, Tsou WL, Joshi GS, Paulson HL, Costa MDC, Scaglione KM, Todi SV. Interaction of the polyglutamine protein ataxin-3 with Rad23 regulates toxicity in Drosophila models of Spinocerebellar Ataxia Type 3. Hum Mol Genet 2017; 26:1419-1431. [PMID: 28158474 DOI: 10.1093/hmg/ddx039] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 01/25/2017] [Indexed: 12/18/2022] Open
Abstract
Polyglutamine (polyQ) repeat expansion in the deubiquitinase ataxin-3 causes neurodegeneration in Spinocerebellar Ataxia Type 3 (SCA3), one of nine inherited, incurable diseases caused by similar mutations. Ataxin-3's degradation is inhibited by its binding to the proteasome shuttle Rad23 through ubiquitin-binding site 2 (UbS2). Disrupting this interaction decreases levels of ataxin-3. Since reducing levels of polyQ proteins can decrease their toxicity, we tested whether genetically modulating the ataxin-3-Rad23 interaction regulates its toxicity in Drosophila. We found that exogenous Rad23 increases the toxicity of pathogenic ataxin-3, coincident with increased levels of the disease protein. Conversely, reducing Rad23 levels alleviates toxicity in this SCA3 model. Unexpectedly, pathogenic ataxin-3 with a mutated Rad23-binding site at UbS2, despite being present at markedly lower levels, proved to be more pathogenic than a disease-causing counterpart with intact UbS2. Additional studies established that the increased toxicity upon mutating UbS2 stems from disrupting the autoprotective role that pathogenic ataxin-3 has against itself, which depends on the co-chaperone, DnaJ-1. Our data reveal a previously unrecognized balance between pathogenic and potentially therapeutic properties of the ataxin-3-Rad23 interaction; they highlight this interaction as critical for the toxicity of the SCA3 protein, and emphasize the importance of considering protein context when pursuing suppressive avenues.
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Affiliation(s)
- Joanna R Sutton
- Department of Pharmacology, Wayne State University, Detroit MI, USA
| | - Jessica R Blount
- Department of Pharmacology, Wayne State University, Detroit MI, USA
| | - Kozeta Libohova
- Department of Pharmacology, Wayne State University, Detroit MI, USA
| | - Wei-Ling Tsou
- Department of Pharmacology, Wayne State University, Detroit MI, USA
| | - Gnanada S Joshi
- Department of Pharmacology, Wayne State University, Detroit MI, USA
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor MI, USA
| | | | - K Matthew Scaglione
- Department of Biochemistry and the Neuroscience Research Center, Medical College of Wisconsin, Milwaukee WI, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University, Detroit MI, USA.,Department of Neurology, Wayne State University, Detroit MI, USA
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Tsou WL, Qiblawi SH, Hosking RR, Gomez CM, Todi SV. Polyglutamine length-dependent toxicity from α1ACT in Drosophila models of spinocerebellar ataxia type 6. Biol Open 2016; 5:1770-1775. [PMID: 27979829 PMCID: PMC5200913 DOI: 10.1242/bio.021667] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Spinocerebellar ataxia type 6 (SCA6) is a neurodegenerative disease that results from abnormal expansion of a polyglutamine (polyQ) repeat. SCA6 is caused by CAG triplet repeat expansion in the gene CACNA1A, resulting in a polyQ tract of 19-33 in patients. CACNA1A, a bicistronic gene, encodes the α1A calcium channel subunit and the transcription factor, α1ACT. PolyQ expansion in α1ACT causes degeneration in mice. We recently described the first Drosophila models of SCA6 that express α1ACT with a normal (11Q) or hyper-expanded (70Q) polyQ. Here, we report additional α1ACT transgenic flies, which express full-length α1ACT with a 33Q repeat. We show that α1ACT33Q is toxic in Drosophila, but less so than the 70Q version. When expressed everywhere, α1ACT33Q-expressing adults die earlier than flies expressing the normal allele. α1ACT33Q causes retinal degeneration and leads to aggregated species in an age-dependent manner, but at a slower pace than the 70Q counterpart. According to western blots, α1ACT33Q localizes less readily in the nucleus than α1ACT70Q, providing clues into the importance of polyQ tract length on α1ACT localization and its site of toxicity. We expect that these new lines will be highly valuable for future work on SCA6.
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Affiliation(s)
- Wei-Ling Tsou
- Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA
| | - Sultan H Qiblawi
- Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA
| | - Ryan R Hosking
- Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA
| | | | - Sokol V Todi
- Department of Pharmacology, Wayne State University, Detroit, MI 48201, USA .,Department of Neurology, Wayne State University, Detroit, MI 48201, USA
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Chaubal A, Todi SV, Pile LA. Inter-isoform-dependent Regulation of the Drosophila Master Transcriptional Regulator SIN3. J Biol Chem 2016; 291:11566-71. [PMID: 27129248 DOI: 10.1074/jbc.c116.724799] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Indexed: 11/06/2022] Open
Abstract
SIN3 is a transcriptional corepressor that acts as a scaffold for a histone deacetylase (HDAC) complex. The SIN3 complex regulates various biological processes, including organ development, cell proliferation, and energy metabolism. Little is known, however, about the regulation of SIN3 itself. There are two major isoforms of Drosophila SIN3, 187 and 220, which are differentially expressed. Intrigued by the developmentally timed exchange of SIN3 isoforms, we examined whether SIN3 187 controls the fate of the 220 counterpart. Here, we show that in developing tissue, there is interplay between SIN3 isoforms: when SIN3 187 protein levels increase, SIN3 220 protein decreases concomitantly. SIN3 187 has a dual effect on SIN3 220. Expression of 187 leads to reduced 220 transcript, while also increasing the turnover of SIN3 220 protein by the proteasome. These data support the presence of a novel, inter-isoform-dependent mechanism that regulates the amount of SIN3 protein, and potentially the level of specific SIN3 complexes, during distinct developmental stages.
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Affiliation(s)
- Ashlesha Chaubal
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and
| | - Sokol V Todi
- the Department of Pharmacology, Wayne State University, Detroit, Michigan 48201
| | - Lori A Pile
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202 and
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Ristic G, Tsou WL, Guzi E, Kanack AJ, Scaglione KM, Todi SV. USP5 Is Dispensable for Monoubiquitin Maintenance in Drosophila. J Biol Chem 2016; 291:9161-72. [PMID: 26917723 DOI: 10.1074/jbc.m115.703504] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Indexed: 11/06/2022] Open
Abstract
Ubiquitination is a post-translational modification that regulates most cellular pathways and processes, including degradation of proteins by the proteasome. Substrate ubiquitination is controlled at various stages, including through its reversal by deubiquitinases (DUBs). A critical outcome of this process is the recycling of monoubiquitin. One DUB whose function has been proposed to include monoubiquitin recycling is USP5. Here, we investigated whether Drosophila USP5 is important for maintaining monoubiquitin in vivo We found that the fruit fly orthologue of USP5 has catalytic preferences similar to its human counterpart and that this DUB is necessary during fly development. Our biochemical and genetic experiments indicate that reduction of USP5 does not lead to monoubiquitin depletion in developing flies. Also, introduction of exogenous ubiquitin does not suppress developmental lethality caused by loss of endogenous USP5. Our work indicates that a primary physiological role of USP5 is not to recycle monoubiquitin for reutilization, but that it may involve disassembly of conjugated ubiquitin to maintain proteasome function.
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Affiliation(s)
| | | | - Ermal Guzi
- From the Departments of Pharmacology and
| | - Adam J Kanack
- the Department of Biochemistry and the Neuroscience Research Center, Medical College of Wisconsin, Milwaukee Wisconsin 53226
| | - Kenneth Matthew Scaglione
- the Department of Biochemistry and the Neuroscience Research Center, Medical College of Wisconsin, Milwaukee Wisconsin 53226
| | - Sokol V Todi
- From the Departments of Pharmacology and Neurology, Wayne State University School of Medicine, Detroit, Michigan 48201 and
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