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Mengel D, Wellik IG, Schuster KH, Jarrah SI, Wacker M, Ashraf NS, Öz G, Synofzik M, Costa MDC, McLoughlin HS. Blood levels of neurofilament light are associated with disease progression in a mouse model of spinocerebellar ataxia type 3. Dis Model Mech 2023; 16:dmm050144. [PMID: 37664882 PMCID: PMC10499033 DOI: 10.1242/dmm.050144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 08/15/2023] [Indexed: 09/05/2023] Open
Abstract
Increased neurofilament light (NfL; NEFL) protein in biofluids is reflective of neurodegeneration and has gained interest as a biomarker across neurodegenerative diseases. In spinocerebellar ataxia type 3 (SCA3), the most common dominantly inherited ataxia, patients exhibit progressive NfL increases in peripheral blood when becoming symptomatic, and NfL remains stably elevated throughout further disease course. However, progressive NfL changes are not yet validated in relevant preclinical SCA3 animal models, hindering its application as a biomarker during therapeutic development. We used ultra-sensitive single-molecule array (Simoa) to measure blood NfL over disease progression in YACQ84 mice, a model of SCA3, assessing relationships with measures of disease severity including age, CAG repeat size and magnetic resonance spectroscopy. YACQ84 mice exhibited plasma NfL increases that were concomitant with ataxia-related motor deficits as well as increased serum NfL, which correlated with previously established neurometabolite abnormalities, two relevant measures of disease in patients with SCA3. Our findings establish the progression of NfL increases in the preclinical YACQ84 mouse, further supporting the utility of blood NfL as a peripheral neurodegeneration biomarker and informing on coinciding timelines of different measures of SCA3 pathogenesis.
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Affiliation(s)
- David Mengel
- Research Division Translational Genomics of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, Tübingen 72076,Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen 72076, Germany
| | - Isabel G. Wellik
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Kristen H. Schuster
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Sabrina I. Jarrah
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Madeleine Wacker
- Research Division Translational Genomics of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, Tübingen 72076,Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen 72076, Germany
| | - Naila S. Ashraf
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Gülin Öz
- Center for Magnetic Resonance Research, Department of Radiology, Medical School, University of Minnesota, Minneapolis, MN 55455, USA
| | - Matthis Synofzik
- Research Division Translational Genomics of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, Tübingen 72076,Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen 72076, Germany
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Ferreira AF, Raposo M, Shaw ED, Ashraf NS, Medeiros F, Brilhante MDF, Perkins M, Vasconcelos J, Kay T, Costa MDC, Lima M. Tissue-Specific Vulnerability to Apoptosis in Machado-Joseph Disease. Cells 2023; 12:1404. [PMID: 37408238 DOI: 10.3390/cells12101404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 05/10/2023] [Accepted: 05/11/2023] [Indexed: 07/07/2023] Open
Abstract
Machado-Joseph disease (MJD) is a dominant neurodegenerative disease caused by an expanded CAG repeat in the ATXN3 gene encoding the ataxin-3 protein. Several cellular processes, including transcription and apoptosis, are disrupted in MJD. To gain further insights into the extent of dysregulation of mitochondrial apoptosis in MJD and to evaluate if expression alterations of specific apoptosis genes/proteins can be used as transcriptional biomarkers of disease, the expression levels of BCL2, BAX and TP53 and the BCL2/BAX ratio (an indicator of susceptibility to apoptosis) were assessed in blood and post-mortem brain samples from MJD subjects and MJD transgenic mice and controls. While patients show reduced levels of blood BCL2 transcripts, this measurement displays low accuracy to discriminate patients from matched controls. However, increased levels of blood BAX transcripts and decreased BCL2/BAX ratio are associated with earlier onset of disease, indicating a possible association with MJD pathogenesis. Post-mortem MJD brains show increased BCL2/BAX transcript ratio in the dentate cerebellar nucleus (DCN) and increased BCL2/BAX insoluble protein ratio in the DCN and pons, suggesting that in these regions, severely affected by degeneration in MJD, cells show signs of apoptosis resistance. Interestingly, a follow-up study of 18 patients further shows that blood BCL2 and TP53 transcript levels increase over time in MJD patients. Furthermore, while the similar levels of blood BCL2, BAX, and TP53 transcripts observed in preclinical subjects and controls is mimicked by pre-symptomatic MJD mice, the expression profile of these genes in patient brains is partially replicated by symptomatic MJD mice. Globally, our findings indicate that there is tissue-specific vulnerability to apoptosis in MJD subjects and that this tissue-dependent behavior is partially replicated in a MJD mouse model.
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Affiliation(s)
- Ana F Ferreira
- Faculdade de Ciências e Tecnologia, Universidade dos Açores, 9500-321 Ponta Delgada, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, 4200-135 Porto, Portugal
| | - Mafalda Raposo
- Instituto de Biologia Molecular e Celular (IBMC), Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, 4200-135 Porto, Portugal
| | - Emily D Shaw
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Naila S Ashraf
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Filipa Medeiros
- Faculdade de Ciências e Tecnologia, Universidade dos Açores, 9500-321 Ponta Delgada, Portugal
| | - Maria de Fátima Brilhante
- Faculdade de Ciências e Tecnologia, Universidade dos Açores, 9500-321 Ponta Delgada, Portugal
- Centro de Estatística e Aplicações, Universidade de Lisboa (CEAUL), 1749-016 Lisboa, Portugal
| | - Matthew Perkins
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - João Vasconcelos
- Serviço de Neurologia, Hospital do Divino Espírito Santo (HDES), 9500-370 Ponta Delgada, Portugal
| | - Teresa Kay
- Serviço de Genética Clínica, Hospital D. Estefânia, 1169-045 Lisboa, Portugal
| | - Maria do Carmo Costa
- Department of Neurology, Michigan Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Manuela Lima
- Faculdade de Ciências e Tecnologia, Universidade dos Açores, 9500-321 Ponta Delgada, Portugal
- Instituto de Biologia Molecular e Celular (IBMC), Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, 4200-135 Porto, Portugal
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Mengel D, Wellik IG, Schuster KH, Jarrah SI, Wacker M, Ashraf NS, Öz G, Synofzik M, do Carmo Costa M, McLoughlin HS. Blood neurofilament light chain levels are associated with disease progression in a transgenic SCA3 mouse model. bioRxiv 2023:2023.02.28.530463. [PMID: 36909535 PMCID: PMC10002656 DOI: 10.1101/2023.02.28.530463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Increased neurofilament light (NfL) protein in biofluids is reflective of neurodegeneration and has gained interest as a biomarker across neurodegenerative diseases. In spinocerebellar ataxia type 3 (SCA3), the most common dominantly inherited ataxia, patients exhibit progressive NfL increases in peripheral blood when becoming symptomatic, remaining stably elevated throughout further disease course. However, progressive NfL changes are not yet validated in relevant preclinical SCA3 animal models, hindering its application as a biomarker during therapeutic development. We used ultra-sensitive single-molecule array (Simoa) to measure blood NfL over disease progression in the YACQ84 mouse, assessing relationships with measures of disease severity including age, CAG repeat size, and magnetic resonance spectroscopy. We show that YACQ84 mice exhibit increased blood NfL, concomitant with ataxia-related motor deficits and correlated with neurometabolite abnormalities. Our findings establish natural history progression of NfL increases in the preclinical YACQ84 mouse, further supporting the utility of blood NfL as a peripheral neurodegeneration biomarker and informing coinciding timelines of different measures of SCA3 pathogenesis. Summary statement Peripheral blood of SCA3 YACQ84 mice exhibits increased abundance of neuronal-specific NfL protein directly associating with disease progression, providing an accessible disease biofluid biomarker to interrogate in preclinical therapeutic studies.
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Affiliation(s)
- David Mengel
- Research Division Translational Genomics of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen, Germany
| | - Isabel G. Wellik
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Madeleine Wacker
- Research Division Translational Genomics of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen, Germany
| | - Naila S. Ashraf
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Gülin Öz
- Center for Magnetic Resonance Research, Department of Radiology, Medical School, University of Minnesota, Minneapolis, MN, USA
| | - Matthis Synofzik
- Research Division Translational Genomics of Neurodegenerative Diseases, Hertie-Institute for Clinical Brain Research and Center of Neurology, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen, Germany
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Costa MDC, Radzwion M, McLoughlin HS, Ashraf NS, Fischer S, Shakkottai VG, Maciel P, Paulson HL, Öz G. In Vivo Molecular Signatures of Cerebellar Pathology in Spinocerebellar Ataxia Type 3. Mov Disord 2020; 35:1774-1786. [PMID: 32621646 PMCID: PMC7572607 DOI: 10.1002/mds.28140] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 05/06/2020] [Accepted: 05/18/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND No treatment exists for the most common dominantly inherited ataxia Machado-Joseph disease, or spinocerebellar ataxia type 3 (SCA3). Successful evaluation of candidate therapeutics will be facilitated by validated noninvasive biomarkers of disease pathology recapitulated by animal models. OBJECTIVE We sought to identify shared in vivo neurochemical signatures in two mouse models of SCA3 that reflect the human disease pathology. METHODS Cerebellar neurochemical concentrations in homozygous YACMJD84.2 (Q84/Q84) and hemizygous CMVMJD135 (Q135) mice were measured by in vivo magnetic resonance spectroscopy at 9.4 tesla. To validate the neurochemical biomarkers, levels of neurofilament medium (NFL; indicator of neuroaxonal integrity) and myelin basic protein (MBP; indicator of myelination) were measured in cerebellar lysates from a subset of mice and patients with SCA3. Finally, NFL and MBP levels were measured in the cerebellar extracts of Q84/Q84 mice upon silencing of the mutant ATXN3 gene. RESULTS Both Q84/Q84 and Q135 mice displayed lower N-acetylaspartate than wild-type littermates, indicating neuroaxonal loss/dysfunction, and lower myo-inositol and total choline, indicating disturbances in phospholipid membrane metabolism and demyelination. Cerebellar NFL and MBP levels were accordingly lower in both models as well as in the cerebellar cortex of patients with SCA3 than controls. Importantly, N-acetylaspartate and total choline correlated with NFL and MPB, respectively, in Q135 mice. Long-term sustained RNA interference (RNAi)-mediated reduction of ATXN3 levels increased NFL and MBP in Q84/Q84 cerebella. CONCLUSIONS N-acetylaspartate, myo-inositol, and total choline levels in the cerebellum are candidate biomarkers of neuroaxonal and oligodendrocyte pathology in SCA3, aspects of pathology that are reversible by RNAi therapy. © 2020 International Parkinson and Movement Disorder Society.
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Affiliation(s)
| | - Maria Radzwion
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | - 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
| | - Vikram G. Shakkottai
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- Departments of Molecular & Integrative Physiology and of Medicine, University of Michigan, Ann Arbor, MI
| | - Patrícia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Portugal
| | - Henry L. Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Gülin Öz
- Center for Magnetic Resonance Research, Department of Radiology, Medical School, University of Minnesota, Minneapolis, MN, USA
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Scaglione KM, Basrur V, Ashraf NS, Konen JR, Elenitoba-Johnson KSJ, Todi SV, Paulson HL. The ubiquitin-conjugating enzyme (E2) Ube2w ubiquitinates the N terminus of substrates. J Biol Chem 2013; 288:18784-8. [PMID: 23696636 DOI: 10.1074/jbc.c113.477596] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Attachment of ubiquitin to substrate is typically thought to occur via formation of an isopeptide bond between the C-terminal glycine residue of ubiquitin and a lysine residue in the substrate. In vitro, Ube2w is nonreactive with free lysine yet readily ubiquitinates substrate. Ube2w also contains novel residues within its active site that are important for its ability to ubiquitinate substrate. To identify the site of modification, we analyzed ubiquitinated substrates by mass spectrometry and found the N-terminal -NH2 group as the site of conjugation. To confirm N-terminal ubiquitination, we generated lysine-less and N-terminally blocked versions of one substrate, the polyglutamine disease protein ataxin-3, and showed that Ube2w can ubiquitinate a lysine-less, but not N-terminally blocked, ataxin-3. This was confirmed with a second substrate, the neurodegenerative disease protein Tau. Finally, we directly sequenced the N terminus of unmodified and ubiquitinated ataxin-3, demonstrating that Ube2w attaches ubiquitin to the N terminus of its substrates. Together these data demonstrate that Ube2w has novel enzymatic properties that direct ubiquitination of the N terminus of substrates.
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