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Costa RG, Conceição A, Matos CA, Nóbrega C. The polyglutamine protein ATXN2: from its molecular functions to its involvement in disease. Cell Death Dis 2024; 15:415. [PMID: 38877004 PMCID: PMC11178924 DOI: 10.1038/s41419-024-06812-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 06/04/2024] [Accepted: 06/05/2024] [Indexed: 06/16/2024]
Abstract
A CAG repeat sequence in the ATXN2 gene encodes a polyglutamine (polyQ) tract within the ataxin-2 (ATXN2) protein, showcasing a complex landscape of functions that have been progressively unveiled over recent decades. Despite significant progresses in the field, a comprehensive overview of the mechanisms governed by ATXN2 remains elusive. This multifaceted protein emerges as a key player in RNA metabolism, stress granules dynamics, endocytosis, calcium signaling, and the regulation of the circadian rhythm. The CAG overexpansion within the ATXN2 gene produces a protein with an extended poly(Q) tract, inducing consequential alterations in conformational dynamics which confer a toxic gain and/or partial loss of function. Although overexpanded ATXN2 is predominantly linked to spinocerebellar ataxia type 2 (SCA2), intermediate expansions are also implicated in amyotrophic lateral sclerosis (ALS) and parkinsonism. While the molecular intricacies await full elucidation, SCA2 presents ATXN2-associated pathological features, encompassing autophagy impairment, RNA-mediated toxicity, heightened oxidative stress, and disruption of calcium homeostasis. Presently, SCA2 remains incurable, with patients reliant on symptomatic and supportive treatments. In the pursuit of therapeutic solutions, various studies have explored avenues ranging from pharmacological drugs to advanced therapies, including cell or gene-based approaches. These endeavours aim to address the root causes or counteract distinct pathological features of SCA2. This review is intended to provide an updated compendium of ATXN2 functions, delineate the associated pathological mechanisms, and present current perspectives on the development of innovative therapeutic strategies.
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Affiliation(s)
- Rafael G Costa
- Algarve Biomedical Center Research Institute (ABC-RI), Faro, Portugal.
- PhD program in Biomedical Sciences, Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal.
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal.
| | - André Conceição
- Algarve Biomedical Center Research Institute (ABC-RI), Faro, Portugal
- PhD program in Biomedical Sciences, Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal
- Center for Neuroscience and Cell Biology (CNC), Coimbra, Portugal
- Champalimaud Research Program, Champalimaud Center for the Unknown, Lisbon, Portugal
| | - Carlos A Matos
- Algarve Biomedical Center Research Institute (ABC-RI), Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal
| | - Clévio Nóbrega
- Algarve Biomedical Center Research Institute (ABC-RI), Faro, Portugal.
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve (UAlg), Faro, Portugal.
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2
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Santarelli S, Londero C, Soldano A, Candelaresi C, Todeschini L, Vernizzi L, Bellosta P. Drosophila melanogaster as a model to study autophagy in neurodegenerative diseases induced by proteinopathies. Front Neurosci 2023; 17:1082047. [PMID: 37274187 PMCID: PMC10232775 DOI: 10.3389/fnins.2023.1082047] [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: 10/27/2022] [Accepted: 04/14/2023] [Indexed: 06/06/2023] Open
Abstract
Proteinopathies are a large group of neurodegenerative diseases caused by both genetic and sporadic mutations in particular genes which can lead to alterations of the protein structure and to the formation of aggregates, especially toxic for neurons. Autophagy is a key mechanism for clearing those aggregates and its function has been strongly associated with the ubiquitin-proteasome system (UPS), hence mutations in both pathways have been associated with the onset of neurodegenerative diseases, particularly those induced by protein misfolding and accumulation of aggregates. Many crucial discoveries regarding the molecular and cellular events underlying the role of autophagy in these diseases have come from studies using Drosophila models. Indeed, despite the physiological and morphological differences between the fly and the human brain, most of the biochemical and molecular aspects regulating protein homeostasis, including autophagy, are conserved between the two species.In this review, we will provide an overview of the most common neurodegenerative proteinopathies, which include PolyQ diseases (Huntington's disease, Spinocerebellar ataxia 1, 2, and 3), Amyotrophic Lateral Sclerosis (C9orf72, SOD1, TDP-43, FUS), Alzheimer's disease (APP, Tau) Parkinson's disease (a-syn, parkin and PINK1, LRRK2) and prion diseases, highlighting the studies using Drosophila that have contributed to understanding the conserved mechanisms and elucidating the role of autophagy in these diseases.
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Affiliation(s)
- Stefania Santarelli
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
| | - Chiara Londero
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
| | - Alessia Soldano
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
- Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
| | - Carlotta Candelaresi
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
| | - Leonardo Todeschini
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
| | - Luisa Vernizzi
- Institute of Molecular Life Sciences, University of Zurich, Zürich, Switzerland
| | - Paola Bellosta
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
- Department of Medicine, NYU Langone Medical Center, New York, NY, United States
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3
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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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4
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Lee WS, Al-Ramahi I, Jeong HH, Jang Y, Lin T, Adamski CJ, Lavery LA, Rath S, Richman R, Bondar VV, Alcala E, Revelli JP, Orr HT, Liu Z, Botas J, Zoghbi HY. Cross-species genetic screens identify transglutaminase 5 as a regulator of polyglutamine-expanded ataxin-1. J Clin Invest 2022; 132:e156616. [PMID: 35499073 PMCID: PMC9057624 DOI: 10.1172/jci156616] [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: 11/10/2021] [Accepted: 03/08/2022] [Indexed: 12/31/2022] Open
Abstract
Many neurodegenerative disorders are caused by abnormal accumulation of misfolded proteins. In spinocerebellar ataxia type 1 (SCA1), accumulation of polyglutamine-expanded (polyQ-expanded) ataxin-1 (ATXN1) causes neuronal toxicity. Lowering total ATXN1, especially the polyQ-expanded form, alleviates disease phenotypes in mice, but the molecular mechanism by which the mutant ATXN1 is specifically modulated is not understood. Here, we identified 22 mutant ATXN1 regulators by performing a cross-species screen of 7787 and 2144 genes in human cells and Drosophila eyes, respectively. Among them, transglutaminase 5 (TG5) preferentially regulated mutant ATXN1 over the WT protein. TG enzymes catalyzed cross-linking of ATXN1 in a polyQ-length-dependent manner, thereby preferentially modulating mutant ATXN1 stability and oligomerization. Perturbing Tg in Drosophila SCA1 models modulated mutant ATXN1 toxicity. Moreover, TG5 was enriched in the nuclei of SCA1-affected neurons and colocalized with nuclear ATXN1 inclusions in brain tissue from patients with SCA1. Our work provides a molecular insight into SCA1 pathogenesis and an opportunity for allele-specific targeting for neurodegenerative disorders.
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Affiliation(s)
- Won-Seok Lee
- Integrative Molecular and Biomedical Science Program, and
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Ismael Al-Ramahi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Hyun-Hwan Jeong
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Department of Pediatrics-Neurology, and
| | - Youjin Jang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Tao Lin
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas, USA
| | - Carolyn J. Adamski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Howard Hughes Medical Institute, Houston, Texas, USA
| | - Laura A. Lavery
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Smruti Rath
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Ronald Richman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Howard Hughes Medical Institute, Houston, Texas, USA
| | - Vitaliy V. Bondar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Elizabeth Alcala
- Exceptional Research Opportunities Program, Howard Hughes Medical Institute, Houston, Texas, USA
| | - Jean-Pierre Revelli
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Harry T. Orr
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Zhandong Liu
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Department of Pediatrics-Neurology, and
| | - Juan Botas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
| | - Huda Y. Zoghbi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Jan and Dan Duncan Neurological Research Institute, Houston, Texas, USA
- Department of Pediatrics-Neurology, and
- Howard Hughes Medical Institute, Houston, Texas, USA
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5
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Huelsmeier J, Walker E, Bakthavachalu B, Ramaswami M. A C-terminal ataxin-2 disordered region promotes Huntingtin protein aggregation and neurodegeneration in Drosophila models of Huntington’s disease. G3 GENES|GENOMES|GENETICS 2021; 11:6385240. [PMID: 34718534 PMCID: PMC8664476 DOI: 10.1093/g3journal/jkab355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/01/2021] [Indexed: 11/15/2022]
Abstract
The Ataxin-2 (Atx2) protein contributes to the progression of neurodegenerative phenotypes in animal models of amyotrophic lateral sclerosis (ALS), type 2 spinocerebellar ataxia (SCA-2), Parkinson’s disease, and Huntington’s disease (HD). However, because the Atx2 protein contains multiple separable activities, deeper understanding requires experiments to address the exact mechanisms by which Atx2 modulates neurodegeneration (ND) progression. Recent work on two ALS models, C9ORF72 and FUS, in Drosophila has shown that a C-terminal intrinsically disordered region (cIDR) of Atx2 protein, required for assembly of ribonucleoprotein (RNP) granules, is essential for the progression of neurodegenerative phenotypes as well as for accumulation of protein inclusions associated with these ALS models. Here, we show that the Atx2-cIDR also similarly contributes to the progression of degenerative phenotypes and accumulation of Huntingtin protein aggregates in Drosophila models of HD. Because Huntingtin is not an established component of RNP granules, these observations support a recently hypothesized, unexpected protein-handling function for RNP granules, which could contribute to the progression of Huntington’s disease and, potentially, other proteinopathies.
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Affiliation(s)
- Joern Huelsmeier
- School of Genetics and Microbiology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Emily Walker
- School of Genetics and Microbiology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Baskar Bakthavachalu
- School of Basic Science, Indian Institute of Technology, Mandi, Suran 175075, India
| | - Mani Ramaswami
- School of Genetics and Microbiology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
- National Centre for Biological Sciences, TIFR, Bangalore 560065, India
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6
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Lee WS, Lavery L, Rousseaux MWC, Rutledge EB, Jang Y, Wan YW, Wu SR, Kim W, Al-Ramahi I, Rath S, Adamski CJ, Bondar VV, Tewari A, Soleimani S, Mota S, Yalamanchili HK, Orr HT, Liu Z, Botas J, Zoghbi HY. Dual targeting of brain region-specific kinases potentiates neurological rescue in Spinocerebellar ataxia type 1. EMBO J 2021; 40:e106106. [PMID: 33709453 DOI: 10.15252/embj.2020106106] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 02/01/2021] [Accepted: 02/10/2021] [Indexed: 12/26/2022] Open
Abstract
A critical question in neurodegeneration is why the accumulation of disease-driving proteins causes selective neuronal loss despite their brain-wide expression. In Spinocerebellar ataxia type 1 (SCA1), accumulation of polyglutamine-expanded Ataxin-1 (ATXN1) causes selective degeneration of cerebellar and brainstem neurons. Previous studies revealed that inhibiting Msk1 reduces phosphorylation of ATXN1 at S776 as well as its levels leading to improved cerebellar function. However, there are no regulators that modulate ATXN1 in the brainstem-the brain region whose pathology is most closely linked to premature death. To identify new regulators of ATXN1, we performed genetic screens and identified a transcription factor-kinase axis (ZBTB7B-RSK3) that regulates ATXN1 levels. Unlike MSK1, RSK3 is highly expressed in the human and mouse brainstems where it regulates Atxn1 by phosphorylating S776. Reducing Rsk3 rescues brainstem-associated pathologies and deficits, and lowering Rsk3 and Msk1 together improves cerebellar and brainstem function in an SCA1 mouse model. Our results demonstrate that selective vulnerability of brain regions in SCA1 is governed by region-specific regulators of ATXN1, and targeting multiple regulators could rescue multiple degenerating brain areas.
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Affiliation(s)
- Won-Seok Lee
- Integrative Molecular and Biomedical Science Program, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Laura Lavery
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Maxime W C Rousseaux
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Eric B Rutledge
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.,Department of Pediatrics-Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Youjin Jang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Ying-Wooi Wan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Sih-Rong Wu
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Wonho Kim
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.,Howard Hughes Medical Institute, Houston, TX, USA
| | - Ismael Al-Ramahi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Smruti Rath
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Carolyn J Adamski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.,Howard Hughes Medical Institute, Houston, TX, USA
| | - Vitaliy V Bondar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Ambika Tewari
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Shirin Soleimani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Samantha Mota
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Hari K Yalamanchili
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.,Department of Pediatrics-Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Harry T Orr
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - Zhandong Liu
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.,Department of Pediatrics-Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Juan Botas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Huda Y Zoghbi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.,Department of Pediatrics-Neurology, Baylor College of Medicine, Houston, TX, USA.,Howard Hughes Medical Institute, Houston, TX, USA
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7
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Canet-Pons J, Sen NE, Arsović A, Almaguer-Mederos LE, Halbach MV, Key J, Döring C, Kerksiek A, Picchiarelli G, Cassel R, René F, Dieterlé S, Fuchs NV, König R, Dupuis L, Lütjohann D, Gispert S, Auburger G. Atxn2-CAG100-KnockIn mouse spinal cord shows progressive TDP43 pathology associated with cholesterol biosynthesis suppression. Neurobiol Dis 2021; 152:105289. [PMID: 33577922 DOI: 10.1016/j.nbd.2021.105289] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/11/2020] [Accepted: 02/03/2021] [Indexed: 12/12/2022] Open
Abstract
Large polyglutamine expansions in Ataxin-2 (ATXN2) cause multi-system nervous atrophy in Spinocerebellar Ataxia type 2 (SCA2). Intermediate size expansions carry a risk for selective motor neuron degeneration, known as Amyotrophic Lateral Sclerosis (ALS). Conversely, the depletion of ATXN2 prevents disease progression in ALS. Although ATXN2 interacts directly with RNA, and in ALS pathogenesis there is a crucial role of RNA toxicity, the affected functional pathways remain ill defined. Here, we examined an authentic SCA2 mouse model with Atxn2-CAG100-KnockIn for a first definition of molecular mechanisms in spinal cord pathology. Neurophysiology of lower limbs detected sensory neuropathy rather than motor denervation. Triple immunofluorescence demonstrated cytosolic ATXN2 aggregates sequestrating TDP43 and TIA1 from the nucleus. In immunoblots, this was accompanied by elevated CASP3, RIPK1 and PQBP1 abundance. RT-qPCR showed increase of Grn, Tlr7 and Rnaset2 mRNA versus Eif5a2, Dcp2, Uhmk1 and Kif5a decrease. These SCA2 findings overlap well with known ALS features. Similar to other ataxias and dystonias, decreased mRNA levels for Unc80, Tacr1, Gnal, Ano3, Kcna2, Elovl5 and Cdr1 contrasted with Gpnmb increase. Preterminal stage tissue showed strongly activated microglia containing ATXN2 aggregates, with parallel astrogliosis. Global transcriptome profiles from stages of incipient motor deficit versus preterminal age identified molecules with progressive downregulation, where a cluster of cholesterol biosynthesis enzymes including Dhcr24, Msmo1, Idi1 and Hmgcs1 was prominent. Gas chromatography demonstrated a massive loss of crucial cholesterol precursor metabolites. Overall, the ATXN2 protein aggregation process affects diverse subcellular compartments, in particular stress granules, endoplasmic reticulum and receptor tyrosine kinase signaling. These findings identify new targets and potential biomarkers for neuroprotective therapies.
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Affiliation(s)
- Júlia Canet-Pons
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Nesli-Ece Sen
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany; Faculty of Biosciences, Goethe University, 60438 Frankfurt am Main, Germany
| | - Aleksandar Arsović
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Luis-Enrique Almaguer-Mederos
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany; Center for Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
| | - Melanie V Halbach
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Jana Key
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany; Faculty of Biosciences, Goethe University, 60438 Frankfurt am Main, Germany
| | - Claudia Döring
- Dr. Senckenberg Institute of Pathology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Anja Kerksiek
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, 53127 Bonn, Nordrhein-Westfalen, Germany
| | - Gina Picchiarelli
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Raphaelle Cassel
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Frédérique René
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Stéphane Dieterlé
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Nina V Fuchs
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225 Langen, Germany
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225 Langen, Germany
| | - Luc Dupuis
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Dieter Lütjohann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, 53127 Bonn, Nordrhein-Westfalen, Germany
| | - Suzana Gispert
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany.
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8
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Arsović A, Halbach MV, Canet-Pons J, Esen-Sehir D, Döring C, Freudenberg F, Czechowska N, Seidel K, Baader SL, Gispert S, Sen NE, Auburger G. Mouse Ataxin-2 Expansion Downregulates CamKII and Other Calcium Signaling Factors, Impairing Granule-Purkinje Neuron Synaptic Strength. Int J Mol Sci 2020; 21:E6673. [PMID: 32932600 PMCID: PMC7555182 DOI: 10.3390/ijms21186673] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/07/2020] [Accepted: 09/10/2020] [Indexed: 12/13/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is caused by polyglutamine expansion in Ataxin-2 (ATXN2). This factor binds RNA/proteins to modify metabolism after stress, and to control calcium (Ca2+) homeostasis after stimuli. Cerebellar ataxias and corticospinal motor neuron degeneration are determined by gain/loss in ATXN2 function, so we aimed to identify key molecules in this atrophic process, as potential disease progression markers. Our Atxn2-CAG100-Knock-In mouse faithfully models features observed in patients at pre-onset, early and terminal stages. Here, its cerebellar global RNA profiling revealed downregulation of signaling cascades to precede motor deficits. Validation work at mRNA/protein level defined alterations that were independent of constant physiological ATXN2 functions, but specific for RNA/aggregation toxicity, and progressive across the short lifespan. The earliest changes were detected at three months among Ca2+ channels/transporters (Itpr1, Ryr3, Atp2a2, Atp2a3, Trpc3), IP3 metabolism (Plcg1, Inpp5a, Itpka), and Ca2+-Calmodulin dependent kinases (Camk2a, Camk4). CaMKIV-Sam68 control over alternative splicing of Nrxn1, an adhesion component of glutamatergic synapses between granule and Purkinje neurons, was found to be affected. Systematic screening of pre/post-synapse components, with dendrite morphology assessment, suggested early impairment of CamKIIα abundance together with the weakening of parallel fiber connectivity. These data reveal molecular changes due to ATXN2 pathology, primarily impacting excitability and communication.
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Affiliation(s)
- Aleksandar Arsović
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
| | - Melanie Vanessa Halbach
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
| | - Júlia Canet-Pons
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
| | - Dilhan Esen-Sehir
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Medical Faculty, Goethe University, Heinrich-Hoffmann-Str. 10, 60528 Frankfurt am Main, Germany; (D.E.-S.); (F.F.)
- Faculty of Biosciences, Goethe-University, Max von Laue Strasse 9, 60438 Frankfurt am Main, Germany
| | - Claudia Döring
- Dr. Senckenberg Institute of Pathology, Goethe University Frankfurt, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany;
| | - Florian Freudenberg
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Medical Faculty, Goethe University, Heinrich-Hoffmann-Str. 10, 60528 Frankfurt am Main, Germany; (D.E.-S.); (F.F.)
| | - Nicoletta Czechowska
- Institute of Anatomy, Anatomy and Cell Biology, University of Bonn, Nussallee 10, 53115 Bonn, Germany; (N.C.); (K.S.); (S.L.B.)
| | - Kay Seidel
- Institute of Anatomy, Anatomy and Cell Biology, University of Bonn, Nussallee 10, 53115 Bonn, Germany; (N.C.); (K.S.); (S.L.B.)
| | - Stephan L. Baader
- Institute of Anatomy, Anatomy and Cell Biology, University of Bonn, Nussallee 10, 53115 Bonn, Germany; (N.C.); (K.S.); (S.L.B.)
| | - Suzana Gispert
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
| | - Nesli-Ece Sen
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
- Faculty of Biosciences, Goethe-University, Max von Laue Strasse 9, 60438 Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (A.A.); (M.V.H.); (J.C.-P.); (S.G.)
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9
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Key J, Harter PN, Sen NE, Gradhand E, Auburger G, Gispert S. Mid-Gestation lethality of Atxn2l-Ablated Mice. Int J Mol Sci 2020; 21:E5124. [PMID: 32698485 PMCID: PMC7404131 DOI: 10.3390/ijms21145124] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/10/2020] [Accepted: 07/16/2020] [Indexed: 12/11/2022] Open
Abstract
Depletion of yeast/fly Ataxin-2 rescues TDP-43 overexpression toxicity. In mouse models of Amyotrophic Lateral Sclerosis via TDP-43 overexpression, depletion of its ortholog ATXN2 mitigated motor neuron degeneration and extended lifespan from 25 days to >300 days. There is another ortholog in mammals, named ATXN2L (Ataxin-2-like), which is almost uncharacterized but also functions in RNA surveillance at stress granules. We generated mice with Crispr/Cas9-mediated deletion of Atxn2l exons 5-8, studying homozygotes prenatally and heterozygotes during aging. Our novel findings indicate that ATXN2L absence triggers mid-gestational embryonic lethality, affecting female animals more strongly. Weight and development stages of homozygous mutants were reduced. Placenta phenotypes were not apparent, but brain histology showed lamination defects and apoptosis. Aged heterozygotes showed no locomotor deficits or weight loss over 12 months. Null mutants in vivo displayed compensatory efforts to maximize Atxn2l expression, which were prevented upon nutrient abundance in vitro. Mouse embryonal fibroblast cells revealed more multinucleated giant cells upon ATXN2L deficiency. In addition, in human neural cells, transcript levels of ATXN2L were induced upon starvation and glucose and amino acids exposure, but this induction was partially prevented by serum or low cholesterol administration. Neither ATXN2L depletion triggered dysregulation of ATXN2, nor a converse effect was observed. Overall, this essential role of ATXN2L for embryogenesis raises questions about its role in neurodegenerative diseases and neuroprotective therapies.
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Affiliation(s)
- Jana Key
- Exp. Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (J.K.); (N.-E.S.)
- Faculty of Biosciences, Goethe-University, Altenhöferallee 1, 60438 Frankfurt am Main, Germany
| | - Patrick N. Harter
- Institute of Neurology (Edinger-Institute), University Hospital Frankfurt, Goethe University, Heinrich-Hoffmann-Strasse 7, 60528 Frankfurt am Main, Germany;
| | - Nesli-Ece Sen
- Exp. Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (J.K.); (N.-E.S.)
- Faculty of Biosciences, Goethe-University, Altenhöferallee 1, 60438 Frankfurt am Main, Germany
| | - Elise Gradhand
- Dr. Senckenberg Institute for Pathology, University Hospital, Goethe University, Theodor-Stern-Kai-7, 60590 Frankfurt am Main, Germany;
| | - Georg Auburger
- Exp. Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (J.K.); (N.-E.S.)
| | - Suzana Gispert
- Exp. Neurology, Medical Faculty, Goethe University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (J.K.); (N.-E.S.)
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10
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Kim T, Song B, Lee IS. Drosophila Glia: Models for Human Neurodevelopmental and Neurodegenerative Disorders. Int J Mol Sci 2020; 21:E4859. [PMID: 32660023 PMCID: PMC7402321 DOI: 10.3390/ijms21144859] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 06/27/2020] [Accepted: 07/07/2020] [Indexed: 12/12/2022] Open
Abstract
Glial cells are key players in the proper formation and maintenance of the nervous system, thus contributing to neuronal health and disease in humans. However, little is known about the molecular pathways that govern glia-neuron communications in the diseased brain. Drosophila provides a useful in vivo model to explore the conserved molecular details of glial cell biology and their contributions to brain function and disease susceptibility. Herein, we review recent studies that explore glial functions in normal neuronal development, along with Drosophila models that seek to identify the pathological implications of glial defects in the context of various central nervous system disorders.
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Affiliation(s)
| | | | - Im-Soon Lee
- Department of Biological Sciences, Center for CHANS, Konkuk University, Seoul 05029, Korea; (T.K.); (B.S.)
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11
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Sen NE, Arsovic A, Meierhofer D, Brodesser S, Oberschmidt C, Canet-Pons J, Kaya ZE, Halbach MV, Gispert S, Sandhoff K, Auburger G. In Human and Mouse Spino-Cerebellar Tissue, Ataxin-2 Expansion Affects Ceramide-Sphingomyelin Metabolism. Int J Mol Sci 2019; 20:E5854. [PMID: 31766565 PMCID: PMC6928749 DOI: 10.3390/ijms20235854] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 02/08/2023] Open
Abstract
Ataxin-2 (human gene symbol ATXN2) acts during stress responses, modulating mRNA translation and nutrient metabolism. Ataxin-2 knockout mice exhibit progressive obesity, dyslipidemia, and insulin resistance. Conversely, the progressive ATXN2 gain of function due to the fact of polyglutamine (polyQ) expansions leads to a dominantly inherited neurodegenerative process named spinocerebellar ataxia type 2 (SCA2) with early adipose tissue loss and late muscle atrophy. We tried to understand lipid dysregulation in a SCA2 patient brain and in an authentic mouse model. Thin layer chromatography of a patient cerebellum was compared to the lipid metabolome of Atxn2-CAG100-Knockin (KIN) mouse spinocerebellar tissue. The human pathology caused deficits of sulfatide, galactosylceramide, cholesterol, C22/24-sphingomyelin, and gangliosides GM1a/GD1b despite quite normal levels of C18-sphingomyelin. Cerebellum and spinal cord from the KIN mouse showed a consistent decrease of various ceramides with a significant elevation of sphingosine in the more severely affected spinal cord. Deficiency of C24/26-sphingomyelins contrasted with excess C18/20-sphingomyelin. Spinocerebellar expression profiling revealed consistent reductions of CERS protein isoforms, Sptlc2 and Smpd3, but upregulation of Cers2 mRNA, as prominent anomalies in the ceramide-sphingosine metabolism. Reduction of Asah2 mRNA correlated to deficient S1P levels. In addition, downregulations for the elongase Elovl1, Elovl4, Elovl5 mRNAs and ELOVL4 protein explain the deficit of very long-chain sphingomyelin. Reduced ASMase protein levels correlated to the accumulation of long-chain sphingomyelin. Overall, a deficit of myelin lipids was prominent in SCA2 nervous tissue at prefinal stage and not compensated by transcriptional adaptation of several metabolic enzymes. Myelination is controlled by mTORC1 signals; thus, our human and murine observations are in agreement with the known role of ATXN2 yeast, nematode, and mouse orthologs as mTORC1 inhibitors and autophagy promoters.
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Affiliation(s)
- Nesli-Ece Sen
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
- Faculty of Biosciences, Goethe-University, 60438 Frankfurt am Main, Germany
| | - Aleksandar Arsovic
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany;
| | - Susanne Brodesser
- Membrane Biology and Lipid Biochemistry Unit, Life and Medical Sciences Institute, University of Bonn, 53121 Bonn, Germany;
| | - Carola Oberschmidt
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Júlia Canet-Pons
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Zeynep-Ece Kaya
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
- Cerrahpasa School of Medicine, Istanbul University, 34098 Istanbul, Turkey
| | - Melanie-Vanessa Halbach
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Suzana Gispert
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Konrad Sandhoff
- Membrane Biology and Lipid Biochemistry Unit, Life and Medical Sciences Institute, University of Bonn, 53121 Bonn, Germany;
| | - Georg Auburger
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
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12
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Xu F, Kula-Eversole E, Iwanaszko M, Lim C, Allada R. Ataxin2 functions via CrebA to mediate Huntingtin toxicity in circadian clock neurons. PLoS Genet 2019; 15:e1008356. [PMID: 31593562 PMCID: PMC6782096 DOI: 10.1371/journal.pgen.1008356] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 08/07/2019] [Indexed: 12/12/2022] Open
Abstract
Disrupted circadian rhythms is a prominent and early feature of neurodegenerative diseases including Huntington’s disease (HD). In HD patients and animal models, striatal and hypothalamic neurons expressing molecular circadian clocks are targets of mutant Huntingtin (mHtt) pathogenicity. Yet how mHtt disrupts circadian rhythms remains unclear. In a genetic screen for modifiers of mHtt effects on circadian behavior in Drosophila, we discovered a role for the neurodegenerative disease gene Ataxin2 (Atx2). Genetic manipulations of Atx2 modify the impact of mHtt on circadian behavior as well as mHtt aggregation and demonstrate a role for Atx2 in promoting mHtt aggregation as well as mHtt-mediated neuronal dysfunction. RNAi knockdown of the Fragile X mental retardation gene, dfmr1, an Atx2 partner, also partially suppresses mHtt effects and Atx2 effects depend on dfmr1. Atx2 knockdown reduces the cAMP response binding protein A (CrebA) transcript at dawn. CrebA transcript level shows a prominent diurnal regulation in clock neurons. Loss of CrebA also partially suppresses mHtt effects on behavior and cell loss and restoration of CrebA can suppress Atx2 effects. Our results indicate a prominent role of Atx2 in mediating mHtt pathology, specifically via its regulation of CrebA, defining a novel molecular pathway in HD pathogenesis. Circadian clocks evolved to anticipate 24 h environmental rhythms driven by the earth’s daily rotation and regulate nearly all aspects of behavior, physiology and the genome. Disruptions of the circadian clock have been associated with a wide range of human diseases, including neurodegenerative diseases such as Huntington’s disease (HD). Using an HD animal model in which a mutant Huntingtin (mHtt) protein is expressed, we identify a role for the RNA binding protein and neurodegenerative disease gene Ataxin-2 (Atx2) in mediating mHtt effects on circadian behavioral rhythms. Using transcriptomics, we identify the transcription factor CrebA as a potential target of both Atx2 and the circadian clock. Finally, we demonstrate a role for CrebA in mediating mHtt effects on circadian behavior, defining a novel Atx2-CrebA pathway in a neurodegenerative disease model. These studies define the molecular mechanisms by which mHtt can disrupt circadian rhythms identifying potential novel therapeutic targets for this uniformly fatal disease.
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Affiliation(s)
- Fangke Xu
- Department of Neurobiology, Northwestern University, Evanston, Illinois, United States of America
| | - Elzbieta Kula-Eversole
- Department of Neurobiology, Northwestern University, Evanston, Illinois, United States of America
| | - Marta Iwanaszko
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Chunghun Lim
- Department of Neurobiology, Northwestern University, Evanston, Illinois, United States of America
| | - Ravi Allada
- Department of Neurobiology, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
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13
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Sen NE, Canet-Pons J, Halbach MV, Arsovic A, Pilatus U, Chae WH, Kaya ZE, Seidel K, Rollmann E, Mittelbronn M, Meierhofer D, De Zeeuw CI, Bosman LWJ, Gispert S, Auburger G. Generation of an Atxn2-CAG100 knock-in mouse reveals N-acetylaspartate production deficit due to early Nat8l dysregulation. Neurobiol Dis 2019; 132:104559. [PMID: 31376479 DOI: 10.1016/j.nbd.2019.104559] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/16/2019] [Accepted: 07/30/2019] [Indexed: 12/13/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disorder caused by CAG-expansion mutations in the ATXN2 gene, mainly affecting motor neurons in the spinal cord and Purkinje neurons in the cerebellum. While the large expansions were shown to cause SCA2, the intermediate length expansions lead to increased risk for several atrophic processes including amyotrophic lateral sclerosis and Parkinson variants, e.g. progressive supranuclear palsy. Intense efforts to pioneer a neuroprotective therapy for SCA2 require longitudinal monitoring of patients and identification of crucial molecular pathways. The ataxin-2 (ATXN2) protein is mainly involved in RNA translation control and regulation of nutrient metabolism during stress periods. The preferential mRNA targets of ATXN2 are yet to be determined. In order to understand the molecular disease mechanism throughout different prognostic stages, we generated an Atxn2-CAG100-knock-in (KIN) mouse model of SCA2 with intact murine ATXN2 expression regulation. Its characterization revealed somatic mosaicism of the expansion, with shortened lifespan, a progressive spatio-temporal pattern of pathology with subsequent phenotypes, and anomalies of brain metabolites such as N-acetylaspartate (NAA), all of which mirror faithfully the findings in SCA2 patients. Novel molecular analyses from stages before the onset of motor deficits revealed a strong selective effect of ATXN2 on Nat8l mRNA which encodes the enzyme responsible for NAA synthesis. This metabolite is a prominent energy store of the brain and a well-established marker for neuronal health. Overall, we present a novel authentic rodent model of SCA2, where in vivo magnetic resonance imaging was feasible to monitor progression and where the definition of earliest transcriptional abnormalities was possible. We believe that this model will not only reveal crucial insights regarding the pathomechanism of SCA2 and other ATXN2-associated disorders, but will also aid in developing gene-targeted therapies and disease prevention.
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Affiliation(s)
- Nesli-Ece Sen
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Júlia Canet-Pons
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Melanie V Halbach
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Aleksandar Arsovic
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Ulrich Pilatus
- Institute of Neuroradiology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Woon-Hyung Chae
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, 60596 Frankfurt am Main, Germany
| | - Zeynep-Ece Kaya
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany; Department of Neurology, Cerrahpasa School of Medicine, Istanbul University, 34098 Istanbul, Turkey
| | - Kay Seidel
- Department of Anatomy II, Institute of Clinical Neuroanatomy, Goethe University, 60590 Frankfurt am Main, Germany
| | - Ewa Rollmann
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Michel Mittelbronn
- Neurological Institute (Edinger Institute), Goethe University, 60590 Frankfurt am Main, Germany; Luxembourg Centre of Neuropathology (LCNP), Luxembourg; Department of Pathology, Laboratoire National de Santé (LNS), Dudelange, Luxembourg; Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Esch-sur-Alzette, Luxembourg; Department of Oncology, NORLUX Neuro-Oncology Laboratory, Luxembourg Institute of Health (LIH), Luxembourg
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Chris I De Zeeuw
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands; Department of Neuroscience, Erasmus Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Laurens W J Bosman
- Department of Neuroscience, Erasmus Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Suzana Gispert
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany.
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14
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Mathis S, Goizet C, Soulages A, Vallat JM, Masson GL. Genetics of amyotrophic lateral sclerosis: A review. J Neurol Sci 2019; 399:217-226. [PMID: 30870681 DOI: 10.1016/j.jns.2019.02.030] [Citation(s) in RCA: 162] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 02/01/2019] [Accepted: 02/20/2019] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder of the motor pathways, invariably leading to death within a few years of onset. Most cases of ALS are sporadic, but familial forms of the disease (FALS) constitute 10% of the cases. Since the first identification of a causative gene in the 1990s and with recent advances in genetics, more than twenty genes have now been linked to FALS. This increased number of genes led to a tremendous amount of research, clearly contributed to a better understanding of the pathophysiology of this disorder, and paved the way for the development of new therapeutics and new hope for this fatal disease.
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Affiliation(s)
- Stéphane Mathis
- Department of Neurology, Nerve-Muscle Unit, CHU Bordeaux, (Pellegrin Hospital), University of Bordeaux, F-33000 Bordeaux, France; ALS Center, Nerve-Muscle Unit, CHU Bordeaux, (Pellegrin Hospital), University of Bordeaux, F-33000 Bordeaux, France.
| | - Cyril Goizet
- Department of Medical Genetics, 'Centre de Référence Maladies Rares Neurogénétique', CHU Bordeaux (Pellegrin Hospital), University of Bordeaux, 33000 Bordeaux, France; Laboratoire MRGM, INSERM U1211, F-33000 Bordeaux, France
| | - Antoine Soulages
- Department of Neurology, Nerve-Muscle Unit, CHU Bordeaux, (Pellegrin Hospital), University of Bordeaux, F-33000 Bordeaux, France
| | - Jean-Michel Vallat
- Department of Neurology, 'Centre de référence neuropathies rares', 2 avenue Martin Luther King, F-87000 Limoges, France
| | - Gwendal Le Masson
- Department of Neurology, Nerve-Muscle Unit, CHU Bordeaux, (Pellegrin Hospital), University of Bordeaux, F-33000 Bordeaux, France; Neurocentre Magendie, 'Physiopathologie de la Plasticité Neuronale', University of Bordeaux, U862, F-33000 Bordeaux, France; INSERM, Neurocentre Magendie, 'Physiopathologie de la Plasticité Neuronale', U862, F-33000 Bordeaux, France
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15
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Papanikolopoulou K, Mudher A, Skoulakis E. An assessment of the translational relevance of Drosophila in drug discovery. Expert Opin Drug Discov 2019; 14:303-313. [PMID: 30664368 DOI: 10.1080/17460441.2019.1569624] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Drosophila melanogaster offers a powerful expedient and economical system with facile genetics. Because of the high sequence and functional conservation with human disease-associated genes, it has been cardinal in deciphering disease mechanisms at the genetic and molecular level. Drosophila are amenable to and respond well to pharmaceutical treatment which coupled to their genetic tractability has led to discovery, repositioning, and validation of a number of compounds. Areas covered: This review summarizes the generation of fly models of human diseases, their advantages and use in elucidation of human disease mechanisms. Representative studies provide examples of the utility of this system in modeling diseases and the discovery, repositioning and testing on pharmaceuticals to ameliorate them. Expert opinion: Drosophila offers a facile and economical whole animal system with many homologous organs to humans, high functional conservation and established methods of generating and validating human disease models. Nevertheless, it remains relatively underused as a drug discovery tool probably because its relevance to mammalian systems remains under question. However, recent exciting success stories using Drosophila disease models for drug screening, repositioning and validation strongly suggest that fly models should figure prominently in the drug discovery pipeline from bench to bedside.
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Affiliation(s)
- Katerina Papanikolopoulou
- a Division of Neuroscience , Biomedical Sciences Research Centre "Alexander Fleming" , Vari , Greece
| | - Amrit Mudher
- b Centre for Biological Sciences , University of Southampton , Southampton , UK
| | - Efthimios Skoulakis
- a Division of Neuroscience , Biomedical Sciences Research Centre "Alexander Fleming" , Vari , Greece
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16
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Bondar VV, Adamski CJ, Onur TS, Tan Q, Wang L, Diaz-Garcia J, Park J, Orr HT, Botas J, Zoghbi HY. PAK1 regulates ATXN1 levels providing an opportunity to modify its toxicity in spinocerebellar ataxia type 1. Hum Mol Genet 2018; 27:2863-2873. [PMID: 29860311 PMCID: PMC6077814 DOI: 10.1093/hmg/ddy200] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 04/23/2018] [Accepted: 05/22/2018] [Indexed: 11/14/2022] Open
Abstract
Spinocerebellar ataxia type 1 (SCA1) is caused by the expansion of a trinucleotide repeat that encodes a polyglutamine tract in ataxin-1 (ATXN1). The expanded polyglutamine in ATXN1 increases the protein's stability and results in its accumulation and toxicity. Previous studies have demonstrated that decreasing ATXN1 levels ameliorates SCA1 phenotypes and pathology in mouse models. We rationalized that reducing ATXN1 levels through pharmacological inhibition of its modulators could provide a therapeutic avenue for SCA1. Here, through a forward genetic screen in Drosophila we identified, p21-activated kinase 3 (Pak3) as a modulator of ATXN1 levels. Loss-of-function of fly Pak3 or Pak1, whose mammalian homologs belong to Group I of PAK proteins, reduces ATXN1 levels, and accordingly, improves disease pathology in a Drosophila model of SCA1. Knockdown of PAK1 potently reduces ATXN1 levels in mammalian cells independent of the well-characterized S776 phosphorylation site (known to stabilize ATXN1) thus revealing a novel molecular pathway that regulates ATXN1 levels. Furthermore, pharmacological inhibition of PAKs decreases ATXN1 levels in a mouse model of SCA1. To explore the potential of using PAK inhibitors in combination therapy, we combined the pharmacological inhibition of PAK with MSK1, a previously identified modulator of ATXN1, and examined their effects on ATXN1 levels. We found that inhibition of both pathways results in an additive decrease in ATXN1 levels. Together, this study identifies PAK signaling as a distinct molecular pathway that regulates ATXN1 levels and presents a promising opportunity to pursue for developing potential therapeutics for SCA1.
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Affiliation(s)
- Vitaliy V Bondar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Carolyn J Adamski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, USA
| | - Tarik S Onur
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Qiumin Tan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Li Wang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Javier Diaz-Garcia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Jeehye Park
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
| | - Harry T Orr
- Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, USA
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA
| | - Juan Botas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
| | - Huda Y Zoghbi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, TX, USA
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
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17
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Karimi-Moghadam A, Charsouei S, Bell B, Jabalameli MR. Parkinson Disease from Mendelian Forms to Genetic Susceptibility: New Molecular Insights into the Neurodegeneration Process. Cell Mol Neurobiol 2018; 38:1153-1178. [PMID: 29700661 PMCID: PMC6061130 DOI: 10.1007/s10571-018-0587-4] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 04/20/2018] [Indexed: 12/13/2022]
Abstract
Parkinson disease (PD) is known as a common progressive neurodegenerative disease which is clinically diagnosed by the manifestation of numerous motor and nonmotor symptoms. PD is a genetically heterogeneous disorder with both familial and sporadic forms. To date, researches in the field of Parkinsonism have identified 23 genes or loci linked to rare monogenic familial forms of PD with Mendelian inheritance. Biochemical studies revealed that the products of these genes usually play key roles in the proper protein and mitochondrial quality control processes, as well as synaptic transmission and vesicular recycling pathways within neurons. Despite this, large number of patients affected with PD typically tends to show sporadic forms of disease with lack of a clear family history. Recent genome-wide association studies (GWAS) meta-analyses on the large sporadic PD case-control samples from European populations have identified over 12 genetic risk factors. However, the genetic etiology that underlies pathogenesis of PD is also discussed, since it remains unidentified in 40% of all PD-affected cases. Nowadays, with the emergence of new genetic techniques, international PD genomics consortiums and public online resources such as PDGene, there are many hopes that future large-scale genetics projects provide further insights into the genetic etiology of PD and improve diagnostic accuracy and therapeutic clinical trial designs.
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Affiliation(s)
- Amin Karimi-Moghadam
- Division of Genetics, Department of Biology, Faculty of Science, University of Isfahan, Isfahan, Iran
| | - Saeid Charsouei
- Department of Neurology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Benjamin Bell
- Human Genetics & Genomic Medicine, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Mohammad Reza Jabalameli
- Division of Genetics, Department of Biology, Faculty of Science, University of Isfahan, Isfahan, Iran.
- Human Genetics & Genomic Medicine, Faculty of Medicine, Southampton General Hospital, University of Southampton, Southampton, UK.
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18
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Ueyama M, Nagai Y. Repeat Expansion Disease Models. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1076:63-78. [PMID: 29951815 DOI: 10.1007/978-981-13-0529-0_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
Repeat expansion disorders are a group of inherited neuromuscular diseases, which are caused by expansion mutations of repeat sequences in the disease-causing genes. Repeat expansion disorders include a class of diseases caused by repeat expansions in the coding region of the genes, producing mutant proteins with amino acid repeats, mostly the polyglutamine (polyQ) diseases, and another class of diseases caused by repeat expansions in the noncoding regions, producing aberrant RNA with expanded repeats, which are called noncoding repeat expansion diseases. A variety of Drosophila disease models have been established for both types of diseases, and they have made significant contributions toward elucidating the molecular mechanisms of and developing therapies for these neuromuscular diseases.
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Affiliation(s)
- Morio Ueyama
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Yoshitaka Nagai
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine, Osaka, Japan.
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19
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Lee J, Kim M, Itoh TQ, Lim C. Ataxin-2: A versatile posttranscriptional regulator and its implication in neural function. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1488. [PMID: 29869836 DOI: 10.1002/wrna.1488] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 05/04/2018] [Accepted: 05/09/2018] [Indexed: 12/13/2022]
Abstract
Ataxin-2 (ATXN2) is a eukaryotic RNA-binding protein that is conserved from yeast to human. Genetic expansion of a poly-glutamine tract in human ATXN2 has been implicated in several neurodegenerative diseases, likely acting through gain-of-function effects. Emerging evidence, however, suggests that ATXN2 plays more direct roles in neural function via specific molecular and cellular pathways. ATXN2 and its associated protein complex control distinct steps in posttranscriptional gene expression, including poly-A tailing, RNA stabilization, microRNA-dependent gene silencing, and translational activation. Specific RNA substrates have been identified for the functions of ATXN2 in aspects of neural physiology, such as circadian rhythms and olfactory habituation. Genetic models of ATXN2 loss-of-function have further revealed its significance in stress-induced cytoplasmic granules, mechanistic target of rapamycin signaling, and cellular metabolism, all of which are crucial for neural homeostasis. Accordingly, we propose that molecular evolution has been selecting the ATXN2 protein complex as an important trans-acting module for the posttranscriptional control of diverse neural functions. This explains how ATXN2 intimately interacts with various neurodegenerative disease genes, and suggests that loss-of-function effects of ATXN2 could be therapeutic targets for ATXN2-related neurological disorders. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Jongbo Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Minjong Kim
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Taichi Q Itoh
- Faculty of Arts and Science, Kyushu University, Fukuoka, Japan
| | - Chunghun Lim
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
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20
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Hamzeiy H, Savaş D, Tunca C, Şen NE, Gündoğdu Eken A, Şahbaz I, Calini D, Tiloca C, Ticozzi N, Ratti A, Silani V, Başak AN. Elevated Global DNA Methylation Is Not Exclusive to Amyotrophic Lateral Sclerosis and Is Also Observed in Spinocerebellar Ataxia Types 1 and 2. NEURODEGENER DIS 2018; 18:38-48. [PMID: 29428949 DOI: 10.1159/000486201] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 12/08/2017] [Indexed: 12/12/2022] Open
Abstract
Adult-onset neurological disorders are caused and influenced by a multitude of different factors, including epigenetic modifications. Here, using an ELISA kit selected upon careful testing, we investigated global 5-methylcytosine (5-mC) levels in sporadic and familial amyotrophic lateral sclerosis (sALS and fALS), spinocerebellar ataxia types 1 and 2 (SCA1 and SCA2), Huntington's disease, Friedreich's ataxia, and myotonic dystrophy type 1. We report a significant elevation in global 5-mC levels of about 2-7% on average for sALS (p < 0.01 [F(1, 243) = 9.159, p = 0.0027]) and various forms of fALS along with SCA1 (p < 0.01 [F(1, 83) = 11.285], p = 0.0012) and SCA2 (p < 0.001 [F(1, 122) = 29.996, p = 0.0001]) when compared to age- and sex-matched healthy controls. C9orf72 expansion carrier ALS patients exhibit the highest global 5-mC levels along with C9orf72 promoter hypermethylation. We failed to measure global 5-hydroxymethylcytosine (5-hmC) levels in blood, probably due to the very low levels of 5-hmC and the limitations of the commercially available ELISA kits. Our results point towards a role for epigenetics modification in ALS, SCA1, and SCA2, and help conclude a dispute on the global 5-mC levels in sALS blood.
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Affiliation(s)
- Hamid Hamzeiy
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Molecular Biology and Genetics Department, Boğaziçi University, Istanbul, Turkey
| | - Doruk Savaş
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Molecular Biology and Genetics Department, Boğaziçi University, Istanbul, Turkey
| | - Ceren Tunca
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Molecular Biology and Genetics Department, Boğaziçi University, Istanbul, Turkey
| | - Nesli Ece Şen
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Molecular Biology and Genetics Department, Boğaziçi University, Istanbul, Turkey
| | - Aslı Gündoğdu Eken
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Molecular Biology and Genetics Department, Boğaziçi University, Istanbul, Turkey
| | - Irmak Şahbaz
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Molecular Biology and Genetics Department, Boğaziçi University, Istanbul, Turkey
| | - Daniela Calini
- Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan, Italy
| | - Cinzia Tiloca
- Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan, Italy
| | - Nicola Ticozzi
- Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan, Italy.,Department of Pathophysiology and Transplantation, "Dino Ferrari" Center, Università degli Studi di Milano, Milan, Italy
| | - Antonia Ratti
- Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan, Italy.,Department of Pathophysiology and Transplantation, "Dino Ferrari" Center, Università degli Studi di Milano, Milan, Italy
| | - Vincenzo Silani
- Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan, Italy.,Department of Pathophysiology and Transplantation, "Dino Ferrari" Center, Università degli Studi di Milano, Milan, Italy
| | - A Nazlı Başak
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Molecular Biology and Genetics Department, Boğaziçi University, Istanbul, Turkey
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21
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Kuo PH, Gan SR, Wang J, Lo RY, Figueroa KP, Tomishon D, Pulst SM, Perlman S, Wilmot G, Gomez CM, Schmahmann JD, Paulson H, Shakkottai VG, Ying SH, Zesiewicz T, Bushara K, Geschwind MD, Xia G, Subramony SH, Ashizawa T, Kuo SH. Dystonia and ataxia progression in spinocerebellar ataxias. Parkinsonism Relat Disord 2017; 45:75-80. [PMID: 29089256 DOI: 10.1016/j.parkreldis.2017.10.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 10/03/2017] [Accepted: 10/09/2017] [Indexed: 12/20/2022]
Abstract
BACKGROUND Dystonia is a common feature in spinocerebellar ataxias (SCAs). Whether the presence of dystonia is associated with different rate of ataxia progression is not known. OBJECTIVES To study clinical characteristics and ataxia progression in SCAs with and without dystonia. METHODS We studied 334 participants with SCA 1, 2, 3 and 6 from the Clinical Research Consortium for Spinocerebellar Ataxias (CRC-SCA) and compared the clinical characteristics of SCAs with and without dystonia. We repeatedly measured ataxia progression by the Scale for Assessment and Rating of Ataxia every 6 months for 2 years. Regression models were employed to study the association between dystonia and ataxia progression after adjusting for age, sex and pathological CAG repeats. We used logistic regression to analyze the impact of different repeat expansion genes on dystonia in SCAs. RESULTS Dystonia was most commonly observed in SCA3, followed by SCA2, SCA1, and SCA6. Dystonia was associated with longer CAG repeats in SCA3. The CAG repeat number in TBP normal alleles appeared to modify the presence of dystonia in SCA1. The presence of dystonia was associated with higher SARA scores in SCA1, 2, and 3. Although relatively rare in SCA6, the presence of dystonia was associated with slower progression of ataxia. CONCLUSIONS The presence of dystonia is associated with greater severity of ataxia in SCA1, 2, and 3, but predictive of a slower progression in SCA6. Complex genetic interactions among repeat expansion genes can lead to diverse clinical symptoms and progression in SCAs.
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Affiliation(s)
- Pei-Hsin Kuo
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Neurology, Buddhist Tzu Chi General Hospital, Tzu Chi University, Hualien, Taiwan
| | - Shi-Rui Gan
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Neurology, Institute of Neurology, First Affiliated Hospital of Fujian Medical University, Fujian Key Laboratory of Molecular Neurology, Fuzhou, China
| | - Jie Wang
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA; Department of Fundamental and Community Nursing, School of Nursing, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Raymond Y Lo
- Department of Neurology, Buddhist Tzu Chi General Hospital, Tzu Chi University, Hualien, Taiwan
| | - Karla P Figueroa
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Darya Tomishon
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Susan Perlman
- Department of Neurology, University of California, Los Angeles, CA, USA
| | - George Wilmot
- Department of Neurology, Emory University, Atlanta, GA, USA
| | | | - Jeremy D Schmahmann
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Henry Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | | | - Sarah H Ying
- Department of Neurology, Johns Hopkins University, Baltimore, MD, USA
| | - Theresa Zesiewicz
- Department of Neurology, University of South Florida, Tampa, FL, USA
| | - Khalaf Bushara
- Department of Neurology, University of Minnesota, Minneapolis, MN, USA
| | | | - Guangbin Xia
- Department of Neurology, University of New Mexico, Albuquerque, NM, USA
| | - S H Subramony
- Department of Neurology, McKnight Brain Institute, University of Florida, Gainsville, FL, USA
| | | | - Sheng-Han Kuo
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
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22
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Halbach MV, Gispert S, Stehning T, Damrath E, Walter M, Auburger G. Atxn2 Knockout and CAG42-Knock-in Cerebellum Shows Similarly Dysregulated Expression in Calcium Homeostasis Pathway. THE CEREBELLUM 2017; 16:68-81. [PMID: 26868665 PMCID: PMC5243904 DOI: 10.1007/s12311-016-0762-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominantly inherited neurodegenerative disorder with preferential affection of Purkinje neurons, which are known as integrators of calcium currents. The expansion of a polyglutamine (polyQ) domain in the RNA-binding protein ataxin-2 (ATXN2) is responsible for this disease, but the causal roles of deficient ATXN2 functions versus aggregation toxicity are still under debate. Here, we studied mouse mutants with Atxn2 knockout (KO) regarding their cerebellar global transcriptome by microarray and RT-qPCR, in comparison with data from Atxn2-CAG42-knock-in (KIN) mouse cerebellum. Global expression downregulations involved lipid and growth signaling pathways in good agreement with previous data. As a novel effect, downregulations of key factors in calcium homeostasis pathways (the transcription factor Rora, transporters Itpr1 and Atp2a2, as well as regulator Inpp5a) were observed in the KO cerebellum, and some of them also occurred subtly early in KIN cerebellum. The ITPR1 protein levels were depleted from soluble fractions of cerebellum in both mutants, but accumulated in its membrane-associated form only in the SCA2 model. Coimmunoprecipitation demonstrated no association of ITPR1 with Q42-expanded or with wild-type ATXN2. These findings provide evidence that the physiological functions and protein interactions of ATXN2 are relevant for calcium-mediated excitation of Purkinje cells as well as for ATXN2-triggered neurotoxicity. These insights may help to understand pathogenesis and tissue specificity in SCA2 and other polyQ ataxias like SCA1, where inositol regulation of calcium flux and RORalpha play a role.
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Affiliation(s)
- Melanie Vanessa Halbach
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany
| | - Suzana Gispert
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany
| | - Tanja Stehning
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany
| | - Ewa Damrath
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany
| | - Michael Walter
- Institute for Medical Genetics, Eberhard-Karls-University of Tuebingen, 72076, Tuebingen, Germany
| | - Georg Auburger
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany.
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23
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Velázquez-Pérez LC, Rodríguez-Labrada R, Fernandez-Ruiz J. Spinocerebellar Ataxia Type 2: Clinicogenetic Aspects, Mechanistic Insights, and Management Approaches. Front Neurol 2017; 8:472. [PMID: 28955296 PMCID: PMC5601978 DOI: 10.3389/fneur.2017.00472] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 08/25/2017] [Indexed: 12/14/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant cerebellar ataxia that occurs as a consequence of abnormal CAG expansions in the ATXN2 gene. Progressive clinical features result from the neurodegeneration of cerebellum and extra-cerebellar structures including the pons, the basal ganglia, and the cerebral cortex. Clinical, electrophysiological, and imaging approaches have been used to characterize the natural history of the disease, allowing its classification into four distinct stages, with special emphasis on the prodromal stage, which is characterized by a plethora of motor and non-motor features. Neuropathological investigations of brain tissue from SCA2 patients reveal a widespread involvement of multiple brain systems, mainly cerebellar and brainstem systems. Recent findings linking ataxin-2 intermediate expansions to other neurodegenerative diseases such as amyotrophic lateral sclerosis have provided insights into the ataxin-2-related toxicity mechanism in neurodegenerative diseases and have raised new ethical challenges to molecular predictive diagnosis of SCA2. No effective neuroprotective therapies are currently available for SCA2 patients, but some therapeutic options such as neurorehabilitation and some emerging neuroprotective drugs have shown palliative benefits.
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Affiliation(s)
- Luis C Velázquez-Pérez
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Medical University of Holguín "Mariana Grajales", Holguín, Cuba
| | - Roberto Rodríguez-Labrada
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Physical Culture School, University of Holguin "Oscar Lucero", Holguín, Cuba
| | - Juan Fernandez-Ruiz
- Department of Physiology, Medicine School, UNAM, Cuernavaca, Mexico.,Psychology School, Universidad Veracruzana, Xalapa, Mexico
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24
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Auburger G, Sen NE, Meierhofer D, Başak AN, Gitler AD. Efficient Prevention of Neurodegenerative Diseases by Depletion of Starvation Response Factor Ataxin-2. Trends Neurosci 2017; 40:507-516. [DOI: 10.1016/j.tins.2017.06.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 06/09/2017] [Indexed: 12/13/2022]
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25
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Dysregulation of mRNA Localization and Translation in Genetic Disease. J Neurosci 2017; 36:11418-11426. [PMID: 27911744 DOI: 10.1523/jneurosci.2352-16.2016] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/01/2016] [Accepted: 09/02/2016] [Indexed: 11/21/2022] Open
Abstract
RNA-binding proteins (RBPs) acting at various steps in the post-transcriptional regulation of gene expression play crucial roles in neuronal development and synaptic plasticity. Genetic mutations affecting several RBPs and associated factors lead to diverse neurological symptoms, as characterized by neurodevelopmental and neuropsychiatric disorders, neuromuscular and neurodegenerative diseases, and can often be multisystemic diseases. We will highlight the physiological roles of a few specific proteins in molecular mechanisms of cytoplasmic mRNA regulation, and how these processes are dysregulated in genetic disease. Recent advances in computational biology and genomewide analysis, integrated with diverse experimental approaches and model systems, have provided new insights into conserved mechanisms and the shared pathobiology of mRNA dysregulation in disease. Progress has been made to understand the pathobiology of disease mechanisms for myotonic dystrophy, spinal muscular atrophy, and fragile X syndrome, with broader implications for other RBP-associated genetic neurological diseases. This gained knowledge of underlying basic mechanisms has paved the way to the development of therapeutic strategies targeting disease mechanisms.
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26
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Ataxin-2: From RNA Control to Human Health and Disease. Genes (Basel) 2017; 8:genes8060157. [PMID: 28587229 PMCID: PMC5485521 DOI: 10.3390/genes8060157] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/23/2017] [Accepted: 05/31/2017] [Indexed: 12/13/2022] Open
Abstract
RNA-binding proteins play fundamental roles in the regulation of molecular processes critical to cellular and organismal homeostasis. Recent studies have identified the RNA-binding protein Ataxin-2 as a genetic determinant or risk factor for various diseases including spinocerebellar ataxia type II (SCA2) and amyotrophic lateral sclerosis (ALS), amongst others. Here, we first discuss the increasingly wide-ranging molecular functions of Ataxin-2, from the regulation of RNA stability and translation to the repression of deleterious accumulation of the RNA-DNA hybrid-harbouring R-loop structures. We also highlight the broader physiological roles of Ataxin-2 such as in the regulation of cellular metabolism and circadian rhythms. Finally, we discuss insight from clinically focused studies to shed light on the impact of molecular and physiological roles of Ataxin-2 in various human diseases. We anticipate that deciphering the fundamental functions of Ataxin-2 will uncover unique approaches to help cure or control debilitating and lethal human diseases.
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27
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An Evolutionarily Conserved Role of Presenilin in Neuronal Protection in the Aging Drosophila Brain. Genetics 2017; 206:1479-1493. [PMID: 28495961 DOI: 10.1534/genetics.116.196881] [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: 10/17/2016] [Accepted: 05/05/2017] [Indexed: 11/18/2022] Open
Abstract
Mutations in the Presenilin genes are the major genetic cause of Alzheimer's disease. Presenilin and Nicastrin are essential components of γ-secretase, a multi-subunit protease that cleaves Type I transmembrane proteins. Genetic studies in mice previously demonstrated that conditional inactivation of Presenilin or Nicastrin in excitatory neurons of the postnatal forebrain results in memory deficits, synaptic impairment, and age-dependent neurodegeneration. The roles of Drosophila Presenilin (Psn) and Nicastrin (Nct) in the adult fly brain, however, are unknown. To knockdown (KD) Psn or Nct selectively in neurons of the adult brain, we generated multiple shRNA lines. Using a ubiquitous driver, these shRNA lines resulted in 80-90% reduction of mRNA and pupal lethality-a phenotype that is shared with Psn and Nct mutants carrying nonsense mutations. Furthermore, expression of these shRNAs in the wing disc caused notching wing phenotypes, which are also shared with Psn and Nct mutants. Similar to Nct, neuron-specific Psn KD using two independent shRNA lines led to early mortality and rough eye phenotypes, which were rescued by a fly Psn transgene. Interestingly, conditional KD (cKD) of Psn or Nct in adult neurons using the elav-Gal4 and tubulin-Gal80ts system caused shortened lifespan, climbing defects, increases in apoptosis, and age-dependent neurodegeneration. Together, these findings demonstrate that, similar to their mammalian counterparts, Drosophila Psn and Nct are required for neuronal survival during aging and normal lifespan, highlighting an evolutionarily conserved role of Presenilin in neuronal protection in the aging brain.
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28
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Carmo-Silva S, Nobrega C, Pereira de Almeida L, Cavadas C. Unraveling the Role of Ataxin-2 in Metabolism. Trends Endocrinol Metab 2017; 28:309-318. [PMID: 28117213 DOI: 10.1016/j.tem.2016.12.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/14/2016] [Accepted: 12/23/2016] [Indexed: 12/21/2022]
Abstract
Ataxin-2 is a polyglutamine protein implicated in several biological processes such as RNA metabolism and cytoskeleton reorganization. Ataxin-2 is highly expressed in various tissues including the hypothalamus, a brain region that controls food intake and energy balance. Ataxin-2 expression is influenced by nutritional status. Emerging studies discussed here now show that ataxin-2 deficiency correlates with insulin resistance and dyslipidemia, an action mediated via the mTOR pathway, suggesting that ataxin-2 might play key roles in metabolic homeostasis including body weight regulation, insulin sensitivity, and cellular stress responses. In this review we also discuss the relevance of ataxin-2 in the hypothalamic regulation of energy balance, and its potential as a therapeutic target in metabolic disorders such as obesity.
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Affiliation(s)
- Sara Carmo-Silva
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Clevio Nobrega
- Department of Biomedical Sciences and Medicine, Center for Biomedical Research (CBMR), University of Algarve, Faro, Portugal
| | - Luís Pereira de Almeida
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Claudia Cavadas
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.
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29
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Seidel G, Meierhofer D, Şen NE, Guenther A, Krobitsch S, Auburger G. Quantitative Global Proteomics of Yeast PBP1 Deletion Mutants and Their Stress Responses Identifies Glucose Metabolism, Mitochondrial, and Stress Granule Changes. J Proteome Res 2016; 16:504-515. [PMID: 27966978 DOI: 10.1021/acs.jproteome.6b00647] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The yeast protein PBP1 is implicated in very diverse pathways. Intriguingly, its deletion mitigates the toxicity of human neurodegeneration factors. Here, we performed label-free quantitative global proteomics to identify crucial downstream factors, either without stress or under cell stress conditions (heat and NaN3). Compared to the wildtype BY4741 strain, PBP1 deletion always triggered downregulation of the key bioenergetics enzyme KGD2 and the prion protein RNQ1 as well as upregulation of the leucine biosynthesis enzyme LEU1. Without stress, enrichment of stress response factors was consistently detected for both deletion mutants; upon stress, these factors were more pronounced. The selective analysis of components of stress granules and P-bodies revealed a prominent downregulation of GIS2. Our yeast data are in good agreement with a global proteomics and metabolomics publication that the PBP1 ortholog ATAXIN-2 (ATXN2) knockout (KO) in mouse results in mitochondrial deficits in leucine/fatty acid catabolism and bioenergetics, with an obesity phenotype. Furthermore, our data provide the completely novel insight that PBP1 mutations in stress periods involve GIS2, a plausible scenario in view of previous data that both PBP1 and GIS2 relocalize from ribosomes to stress granules, interact with poly(A)-binding protein in translation regulation and prevent mitochondrial precursor overaccumulation stress (mPOS). This may be relevant for human diseases like spinocerebellar ataxias, amyotrophic lateral sclerosis, and the metabolic syndrome.
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Affiliation(s)
- Gunnar Seidel
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Nesli-Ece Şen
- Experimental Neurology, Goethe University Medical School , Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Anika Guenther
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Sylvia Krobitsch
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Georg Auburger
- Experimental Neurology, Goethe University Medical School , Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
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Alves-Cruzeiro JMDC, Mendonça L, Pereira de Almeida L, Nóbrega C. Motor Dysfunctions and Neuropathology in Mouse Models of Spinocerebellar Ataxia Type 2: A Comprehensive Review. Front Neurosci 2016; 10:572. [PMID: 28018166 PMCID: PMC5156697 DOI: 10.3389/fnins.2016.00572] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 11/28/2016] [Indexed: 12/16/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant ataxia caused by an expansion of CAG repeats in the exon 1 of the gene ATXN2, conferring a gain of toxic function that triggers the appearance of the disease phenotype. SCA2 is characterized by several symptoms including progressive gait ataxia and dysarthria, slow saccadic eye movements, sleep disturbances, cognitive impairments, and psychological dysfunctions such as insomnia and depression, among others. The available treatments rely on palliative care, which mitigate some of the major symptoms but ultimately fail to block the disease progression. This persistent lack of effective therapies led to the development of several models in yeast, C. elegans, D. melanogaster, and mice to serve as platforms for testing new therapeutic strategies and to accelerate the research on the complex disease mechanisms. In this work, we review 4 transgenic and 1 knock-in mouse that exhibit a SCA2-related phenotype and discuss their usefulness in addressing different scientific problems. The knock-in mice are extremely faithful to the human disease, with late onset of symptoms and physiological levels of mutant ataxin-2, while the other transgenic possess robust and well-characterized motor impairments and neuropathological features. Furthermore, a new BAC model of SCA2 shows promise to study the recently explored role of non-coding RNAs as a major pathogenic mechanism in this devastating disorder. Focusing on specific aspects of the behavior and neuropathology, as well as technical aspects, we provide a highly practical description and comparison of all the models with the purpose of creating a useful resource for SCA2 researchers worldwide.
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Affiliation(s)
| | - Liliana Mendonça
- Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Luís Pereira de Almeida
- Center for Neuroscience and Cell Biology, University of CoimbraCoimbra, Portugal; Faculty of Pharmacy, University of CoimbraCoimbra, Portugal
| | - Clévio Nóbrega
- Department of Biomedical Sciences and Medicine and Center for Biomedical Research, University of Algarve Faro, Portugal
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Vianna MCB, Poleto DC, Gomes PF, Valente V, Paçó‐Larson ML. Drosophila ataxin-2 gene encodes two differentially expressed isoforms and its function in larval fat body is crucial for development of peripheral tissues. FEBS Open Bio 2016; 6:1040-1053. [PMID: 27833845 PMCID: PMC5095142 DOI: 10.1002/2211-5463.12124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 08/02/2016] [Accepted: 09/01/2016] [Indexed: 01/28/2023] Open
Abstract
Different isoforms of ataxin‐2 are predicted in Drosophila and may underlie different cellular processes. Here, we validated the isoforms B and C of Drosophila ataxin‐2 locus (dAtx2), which we found to be expressed in various tissues and at different levels during development. dAtx2‐B mRNA was detected at low amounts during all developmental stages, whereas dAtx2‐C mRNA levels increase by eightfold from L3 to pupal–adult stages. Higher amounts of dAtx2‐B protein were detected in embryos, while dAtx2‐C protein was also expressed in higher levels in pupal–adult stages, indicating post‐transcriptional control for isoform B and transcription induction for isoform C, respectively. Moreover, in the fat body of L3 larvae dAtx2‐C, but not dAtx2‐B, accumulates in cytoplasmic foci that colocalize with sec23, a marker of endoplasmic reticulum exit sites (ERES). Interestingly, animals subjected to selective knockdown of dAtx2 in the larval fat body do not complete metamorphosis and die at the third larval stage or early puparium. Additionally, larvae knocked down for dAtx2, grown at 29 °C, are significantly smaller than control animals due to reduction in DNA replication and cell growth, which are consistent with the decreased levels of phosphorylated‐AKT observed in the fat body. Based on the localization of ataxin‐2 (dAtx2‐C) in ERESs, and on the phenotypes observed by dAtx2 knockdown in the larval fat body, we speculate a possible role for this protein in processes that regulate ERES formation. These data provide new insights into the biological function of ataxin‐2 with potential relevance to neurodegenerative diseases.
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Affiliation(s)
- Murilo Carlos Bizam Vianna
- Department of Cellular and Molecular BiologyRibeirão Preto School of MedicineUniversity of São PauloRibeirão PretoSPBrazil
- Present address: Center of Biological SciencesState University of LondrinaCampus Universitário, LondrinaPR 86057‐97Brazil
| | - Deise Cristina Poleto
- Department of Cellular and Molecular BiologyRibeirão Preto School of MedicineUniversity of São PauloRibeirão PretoSPBrazil
| | - Paula Fernanda Gomes
- Department of Cellular and Molecular BiologyRibeirão Preto School of MedicineUniversity of São PauloRibeirão PretoSPBrazil
| | - Valéria Valente
- Department of Cellular and Molecular BiologyRibeirão Preto School of MedicineUniversity of São PauloRibeirão PretoSPBrazil
- Present address: Department of Clinical AnalysisFaculty of Pharmaceutical Sciences of AraraquaraUniversity of São Paulo State (UNESP)R. Expedicionários do Brasil, 1628, AraraquaraSP 14801‐902Brazil
| | - Maria Luisa Paçó‐Larson
- Department of Cellular and Molecular BiologyRibeirão Preto School of MedicineUniversity of São PauloRibeirão PretoSPBrazil
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Sen NE, Drost J, Gispert S, Torres-Odio S, Damrath E, Klinkenberg M, Hamzeiy H, Akdal G, Güllüoğlu H, Başak AN, Auburger G. Search for SCA2 blood RNA biomarkers highlights Ataxin-2 as strong modifier of the mitochondrial factor PINK1 levels. Neurobiol Dis 2016; 96:115-126. [PMID: 27597528 DOI: 10.1016/j.nbd.2016.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/24/2016] [Accepted: 09/01/2016] [Indexed: 12/13/2022] Open
Abstract
Ataxin-2 (ATXN2) polyglutamine domain expansions of large size result in an autosomal dominantly inherited multi-system-atrophy of the nervous system named spinocerebellar ataxia type 2 (SCA2), while expansions of intermediate size act as polygenic risk factors for motor neuron disease (ALS and FTLD) and perhaps also for Levodopa-responsive Parkinson's disease (PD). In view of the established role of ATXN2 for RNA processing in periods of cell stress and the expression of ATXN2 in blood cells such as platelets, we investigated whether global deep RNA sequencing of whole blood from SCA2 patients identifies a molecular profile which might serve as diagnostic biomarker. The bioinformatic analysis of SCA2 blood global transcriptomics revealed various significant effects on RNA processing pathways, as well as the pathways of Huntington's disease and PD where mitochondrial dysfunction is crucial. Notably, an induction of PINK1 and PARK7 expression was observed. Conversely, expression of Pink1 was severely decreased upon global transcriptome profiling of Atxn2-knockout mouse cerebellum and liver, in parallel to strong effects on Opa1 and Ghitm, which encode known mitochondrial dynamics regulators. These results were validated by quantitative PCR and immunoblots. Starvation stress of human SH-SY5Y neuroblastoma cells led to a transcriptional phasic induction of ATXN2 in parallel to PINK1, and the knockdown of one enhanced the expression of the other during stress response. These findings suggest that ATXN2 may modify the known PINK1 roles for mitochondrial quality control and autophagy during cell stress. Given that PINK1 is responsible for autosomal recessive juvenile PD, this genetic interaction provides a concept how the degeneration of nigrostriatal dopaminergic neurons and the Parkinson phenotype may be triggered by ATXN2 mutations.
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Affiliation(s)
- Nesli Ece Sen
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany; Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Boğaziçi University, 34342 Istanbul, Turkey
| | - Jessica Drost
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Suzana Gispert
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Sylvia Torres-Odio
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Ewa Damrath
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Michael Klinkenberg
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany
| | - Hamid Hamzeiy
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Boğaziçi University, 34342 Istanbul, Turkey
| | - Gülden Akdal
- Department of Neurology, Faculty of Medicine, Dokuz Eylül University, Izmir, Turkey
| | - Halil Güllüoğlu
- Department of Neurology, Faculty of Medicine, Izmir University, Izmir, Turkey
| | - A Nazlı Başak
- Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Boğaziçi University, 34342 Istanbul, Turkey.
| | - Georg Auburger
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt/Main, Germany.
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Meierhofer D, Halbach M, Şen NE, Gispert S, Auburger G. Ataxin-2 (Atxn2)-Knock-Out Mice Show Branched Chain Amino Acids and Fatty Acids Pathway Alterations. Mol Cell Proteomics 2016; 15:1728-39. [PMID: 26850065 DOI: 10.1074/mcp.m115.056770] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Indexed: 12/13/2022] Open
Abstract
Human Ataxin-2 (ATXN2) gene locus variants have been associated with obesity, diabetes mellitus type 1,and hypertension in genome-wide association studies, whereas mouse studies showed the knock-out of Atxn2 to lead to obesity, insulin resistance, and dyslipidemia. Intriguingly, the deficiency of ATXN2 protein orthologs in yeast and flies rescues the neurodegeneration process triggered by TDP-43 and Ataxin-1 toxicity. To understand the molecular effects of ATXN2 deficiency by unbiased approaches, we quantified the global proteome and metabolome of Atxn2-knock-out mice with label-free mass spectrometry. In liver tissue, significant downregulations of the proteins ACADS, ALDH6A1, ALDH7A1, IVD, MCCC2, PCCA, OTC, together with bioinformatic enrichment of downregulated pathways for branched chain and other amino acid metabolism, fatty acids, and citric acid cycle were observed. Statistical trends in the cerebellar proteome and in the metabolomic profiles supported these findings. They are in good agreement with recent claims that PBP1, the yeast ortholog of ATXN2, sequestrates the nutrient sensor TORC1 in periods of cell stress. Overall, ATXN2 appears to modulate nutrition and metabolism, and its activity changes are determinants of growth excess or cell atrophy.
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Affiliation(s)
- David Meierhofer
- From the ‡Max Planck Institute for Molecular Genetics, Ihnestraβe 63-73, 14195 Berlin, Germany;
| | - Melanie Halbach
- §Experimental Neurology, Building 89, Goethe University Medical School, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Nesli Ece Şen
- §Experimental Neurology, Building 89, Goethe University Medical School, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Suzana Gispert
- §Experimental Neurology, Building 89, Goethe University Medical School, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Georg Auburger
- §Experimental Neurology, Building 89, Goethe University Medical School, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
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Nóbrega C, Carmo-Silva S, Albuquerque D, Vasconcelos-Ferreira A, Vijayakumar UG, Mendonça L, Hirai H, de Almeida LP. Re-establishing ataxin-2 downregulates translation of mutant ataxin-3 and alleviates Machado-Joseph disease. Brain 2015; 138:3537-54. [PMID: 26490332 DOI: 10.1093/brain/awv298] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 08/25/2015] [Indexed: 01/09/2023] Open
Abstract
Machado-Joseph disease is a progressive neurodegenerative disorder associated with the polyQ-expanded ataxin-3 (encoded by ATXN3), for which no therapy is available. With the aim of clarifying the mechanism of neurodegeneration, we hypothesized that the abnormally long polyQ tract would interact aberrantly with ataxin-2 (encoded by ATXN2), another polyQ protein whose function has recently been linked to translational regulation. Using patient's samples and cellular and animal's models we found that in Machado-Joseph disease: (i) ataxin-2 levels are reduced; and (ii) its subcellular localization is changed towards the nucleus. Restoring ataxin-2 levels by lentiviral-mediated overexpression: (i) reduced mutant ataxin-3 levels; and (ii) rescued behaviour defects and neuropathology in a transgenic mouse model of Machado-Joseph disease. Conversely (i) mutating the ataxin-2 motif that enables binding to its natural interactor and translation activator poly(A)-binding protein; or (ii) overexpressing poly(A)-binding protein, had opposite effects, increasing mutant ataxin-3 translation and aggregation. This work suggests that in Machado-Joseph disease, mutant ataxin-3 drives an abnormal reduction of ataxin-2 levels, which overactivates poly(A)-binding protein, increases translation of mutant ataxin-3 and other proteins and aggravates Machado-Joseph disease. Re-establishment of ataxin-2 levels reduces mutant ataxin-3 and alleviates Machado-Joseph disease pathogenesis opening a new avenue for therapeutic intervention in this and potentially other polyQ disorders.
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Affiliation(s)
- Clévio Nóbrega
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal
| | - Sara Carmo-Silva
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal 2 Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
| | - David Albuquerque
- 3 Faculty of Sciences and Technology, University of Coimbra, 3004- 517 Coimbra, Portugal
| | - Ana Vasconcelos-Ferreira
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal 2 Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Udaya-Geetha Vijayakumar
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal
| | - Liliana Mendonça
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal
| | - Hirokazu Hirai
- 4 Department of Neurophysiology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
| | - Luís Pereira de Almeida
- 1 CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Rua Larga, FMUC, 3004- 504 Coimbra, Portugal 2 Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
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Ruden DM, Cingolani PE, Sen A, Qu W, Wang L, Senut MC, Garfinkel MD, Sollars VE, Lu X. Epigenetics as an answer to Darwin's "special difficulty," Part 2: natural selection of metastable epialleles in honeybee castes. Front Genet 2015; 6:60. [PMID: 25759717 PMCID: PMC4338822 DOI: 10.3389/fgene.2015.00060] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Accepted: 02/08/2015] [Indexed: 11/15/2022] Open
Abstract
In a recent perspective in this journal, Herb (2014) discussed how epigenetics is a possible mechanism to circumvent Charles Darwin's "special difficulty" in using natural selection to explain the existence of the sterile-fertile dimorphism in eusocial insects. Darwin's classic book "On the Origin of Species by Means of Natural Selection" explains how natural selection of the fittest individuals in a population can allow a species to adapt to a novel or changing environment. However, in bees and other eusocial insects, such as ants and termites, there exist two or more castes of genetically similar females, from fertile queens to multiple sub-castes of sterile workers, with vastly different phenotypes, lifespans, and behaviors. This necessitates the selection of groups (or kin) rather than individuals in the evolution of honeybee hives, but group and kin selection theories of evolution are controversial and mechanistically uncertain. Also, group selection would seem to be prohibitively inefficient because the effective population size of a colony is reduced from thousands to a single breeding queen. In this follow-up perspective, we elaborate on possible mechanisms for how a combination of both epigenetics, specifically, the selection of metastable epialleles, and genetics, the selection of mutations generated by the selected metastable epialleles, allows for a combined means for selection amongst the fertile members of a species to increase colony fitness. This "intra-caste evolution" hypothesis is a variation of the epigenetic directed genetic error hypothesis, which proposes that selected metastable epialleles increase genetic variability by directing mutations specifically to the epialleles. Natural selection of random metastable epialleles followed by a second round of natural selection of random mutations generated by the metastable epialleles would allow a way around the small effective population size of eusocial insects.
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Affiliation(s)
- Douglas M. Ruden
- Department of Obstetrics and Gynecology, C. S. Mott Center for Human Growth and Development and Center for Urban Responses to Environmental Stressors, Institute of Environmental Health Sciences, Wayne State UniversityDetroit, MI, USA
| | - Pablo E. Cingolani
- School of Computer Science and Genome Quebec Innovation Centre, McGill UniversityMontreal, QC, Canada
| | - Arko Sen
- Department of Pharmacology, Wayne State UniversityDetroit, MI, USA
| | - Wen Qu
- Department of Pharmacology, Wayne State UniversityDetroit, MI, USA
| | - Luan Wang
- Institute of Environmental Health Sciences, Wayne State UniversityDetroit, MI, USA
| | - Marie-Claude Senut
- Institute of Environmental Health Sciences, Wayne State UniversityDetroit, MI, USA
| | - Mark D. Garfinkel
- Department of Biological Sciences, University of Alabama in HuntsvilleHuntsville, AL, USA
| | - Vincent E. Sollars
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall UniversityHuntington, WV, USA
| | - Xiangyi Lu
- Institute of Environmental Health Sciences, Wayne State UniversityDetroit, MI, USA
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Role of dynamic and mitochondrial mutations in neurodegenerative diseases with ataxia: lower repeats and LNAs at multiple loci as alternative pathogenesis. J Mol Neurosci 2014; 54:837-47. [PMID: 25303857 DOI: 10.1007/s12031-014-0431-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 09/24/2014] [Indexed: 10/24/2022]
Abstract
Spinocerebellar ataxia is a growing group of hereditary neurodegenerative diseases for which ≥30 different genetic loci have been identified. In this study, we assessed the repeats at eight spinocerebellar ataxia (SCA) loci in 188 clinical SCA patients and 100 individuals without any neurological signs. Results from the present study were able to identify 16/188 (8.5%) clinical ataxia patients with repeat expansions in the pathological range of SCA genes, with the majority having expansion at the SCA1, 2, and 3 loci. The present study further evaluated two mitochondrial mutations associated with ataxia, i.e., T8993G and A8344G. Six patients were identified with A8344G mutation and none had the mutation in ATPase 6 gene; however, G8994A variation was found in three cases. Overall, three cases had triplet repeat expansions as well as mitochondrial (mt) mutations, which indicates potential association of triplet repeat expansions and mitochondrial mutations. Both the molecular analysis of several SCA loci and two relevant mt mutations indicated that the majority of ataxia cases were still undiagnosed; hence, the following hypotheses were proposed and tested based on available data: (i) lower repeats than normal range and (ii) large normal alleles (LNAs) at multiple loci may be an alternative basis for disease pathogenesis.
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37
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Burr AA, Tsou WL, Ristic G, Todi SV. Using membrane-targeted green fluorescent protein to monitor neurotoxic protein-dependent degeneration of Drosophila eyes. J Neurosci Res 2014; 92:1100-9. [PMID: 24798551 DOI: 10.1002/jnr.23395] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 03/07/2014] [Accepted: 04/01/2014] [Indexed: 12/27/2022]
Abstract
Age-related neurodegeneration has been studied extensively through the use of model organisms, including the genetically versatile Drosophila melanogaster. Various neurotoxic proteins have been expressed in fly eyes to approximate degeneration occurring in humans, and much has been learned from this heterologous system. Although Drosophila expedites scientific research through rapid generational times and relative inexpensiveness, one factor that can hinder analyses is the examination of milder forms of degeneration caused by some toxic proteins in fly eyes. Whereas several disease proteins cause massive degeneration that is easily observed by examining the external structure of the fly eye, others cause mild degeneration that is difficult to observe externally and requires laborious histological preparation to assess and monitor. Here, we describe a sensitive fluorescence-based method to observe, monitor, and quantify mild Drosophila eye degeneration caused by various proteins, including the polyglutamine disease proteins ataxin-3 (spinocerebellar ataxia type 3) and huntingtin (Huntington's disease), mutant α-synuclein (Parkinson's disease), and Aβ42 (Alzheimer's disease). We show that membrane-targeted green fluorescent protein reports degeneration robustly and quantitatively. This simple yet powerful technique, which is amenable to large-scale screens, can help accelerate studies to understand age-related degeneration and to find factors that suppress it for therapeutic purposes.
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Affiliation(s)
- Aaron A Burr
- Graduate Program in Cancer Biology, Wayne State University School of Medicine, Detroit, Michigan; Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan
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38
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Medved V, Huang ZY, Popadic A. Ubx promotes corbicular development in Apis mellifera. Biol Lett 2014; 10:20131021. [PMID: 24478202 DOI: 10.1098/rsbl.2013.1021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The key morphological feature that distinguishes corbiculate bees from other members of the Apidae family is the presence of the corbicula (pollen basket) on the tibial segment of hind legs. Here, we show that in the honeybee (Apis mellifera), the depletion of the gene Ultrabithorax (Ubx) by RNAi transforms the corbicula from a smooth, bristle-free concave structure to one covered with bristles. This is accompanied by a reduction of the pollen press, which is located on the basitarsus and used for packing the pollen pellet as well as a loss of the orderly arrangement of the rows of bristles that form the pollen comb. All these changes make the overall identity of workers' T3 legs assume that of the queen. Furthermore, in a corbiculate bee of a different genus, Bombus impatiens, Ubx expression is also localized in T3 tibia and basitarsus. These observations suggest that the evolution of the pollen gathering apparatus in corbiculate bees may have a shared origin and could be traced to the acquisition of novel functions by Ubx, which in Apis were instrumental for subsequent castes and behavioural differentiation.
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Affiliation(s)
- Victor Medved
- Department of Biological Sciences, Wayne State University, , Detroit, MI, USA
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Yamashita C, Tomiyama H, Funayama M, Inamizu S, Ando M, Li Y, Yoshino H, Araki T, Ichikawa T, Ehara Y, Ishikawa K, Mizusawa H, Hattori N. Evaluation of polyglutamine repeats in autosomal dominant Parkinson's disease. Neurobiol Aging 2014; 35:1779.e17-21. [PMID: 24534762 DOI: 10.1016/j.neurobiolaging.2014.01.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 01/20/2014] [Accepted: 01/21/2014] [Indexed: 12/13/2022]
Abstract
We evaluated the contributions of various polyglutamine (polyQ) disease genes to Parkinson's disease (PD). We compared the distributions of polyQ repeat lengths in 8 common genes (ATXN1, ATXN2, ATXN3, CACNA1A, ATXN7, TBP, ATN1, and HTT) in 299 unrelated patients with autosomal dominant PD (ADPD) and 329 normal controls. We also analyzed the possibility of genetic interactions between ATXN1 and ATXN2, ATXN2 and ATXN3, and ATXN2 and CACNA1A. Intermediate-length polyQ expansions (>24 Qs) of ATXN2 were found in 7 ADPD patients and no controls (7/299 = 2.34% and 0/329 = 0%, respectively; p = 0.0053 < 0.05/8 after Bonferroni correction). These patients showed typical L-DOPA-responsive PD phenotypes. Conversely, no significant differences in polyQ repeat lengths were found between the ADPD patients and the controls for the other 7 genes. Our results may support the hypothesis that ATXN2 polyQ expansion is a specific predisposing factor for multiple neurodegenerative diseases.
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Affiliation(s)
- Chikara Yamashita
- Department of Neurology, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan
| | - Hiroyuki Tomiyama
- Department of Neurology, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan; Department of Neuroscience for Neurodegenerative Disorders, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan
| | - Manabu Funayama
- Department of Neurology, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan; Research Institute for Diseases of Old Age, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan
| | - Saeko Inamizu
- Department of Neurology, Hiroshima Red Cross Hospital & Atomic-bomb Survivors Hospital, Naka-ku, Hiroshima, Japan
| | - Maya Ando
- Department of Neurology, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan
| | - Yuanzhe Li
- Research Institute for Diseases of Old Age, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan
| | - Hiroyo Yoshino
- Research Institute for Diseases of Old Age, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan
| | - Takehisa Araki
- Department of Neurology, Hiroshima Red Cross Hospital & Atomic-bomb Survivors Hospital, Naka-ku, Hiroshima, Japan
| | - Tadashi Ichikawa
- Department of Neurology, Saitama Prefectural Rehablitation Center, Ageo-city, Saitama, Japan
| | - Yoshiro Ehara
- Department of Medical Education, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan
| | - Kinya Ishikawa
- Department of Neurology and Neurological Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
| | - Hidehiro Mizusawa
- Department of Neurology and Neurological Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
| | - Nobutaka Hattori
- Department of Neurology, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan; Department of Neuroscience for Neurodegenerative Disorders, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan; Research Institute for Diseases of Old Age, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan.
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A functional deficiency of TERA/VCP/p97 contributes to impaired DNA repair in multiple polyglutamine diseases. Nat Commun 2013; 4:1816. [PMID: 23652004 DOI: 10.1038/ncomms2828] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 03/11/2013] [Accepted: 04/03/2013] [Indexed: 11/08/2022] Open
Abstract
It is hypothesized that a common underlying mechanism links multiple neurodegenerative disorders. Here we show that transitional endoplasmic reticulum ATPase (TERA)/valosin-containing protein (VCP)/p97 directly binds to multiple polyglutamine disease proteins (huntingtin, ataxin-1, ataxin-7 and androgen receptor) via polyglutamine sequence. Although normal and mutant polyglutamine proteins interact with TERA/VCP/p97, only mutant proteins affect dynamism of TERA/VCP/p97. Among multiple functions of TERA/VCP/p97, we reveal that functional defect of TERA/VCP/p97 in DNA double-stranded break repair is critical for the pathology of neurons in which TERA/VCP/p97 is located dominantly in the nucleus in vivo. Mutant polyglutamine proteins impair accumulation of TERA/VCP/p97 and interaction of related double-stranded break repair proteins, finally causing the increase of unrepaired double-stranded break. Consistently, the recovery of lifespan in polyglutamine disease fly models by TERA/VCP/p97 corresponds well to the improvement of double-stranded break in neurons. Taken together, our results provide a novel common pathomechanism in multiple polyglutamine diseases that is mediated by DNA repair function of TERA/VCP/p97.
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FMRP and Ataxin-2 function together in long-term olfactory habituation and neuronal translational control. Proc Natl Acad Sci U S A 2013; 111:E99-E108. [PMID: 24344294 DOI: 10.1073/pnas.1309543111] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Fragile X mental retardation protein (FMRP) and Ataxin-2 (Atx2) are triplet expansion disease- and stress granule-associated proteins implicated in neuronal translational control and microRNA function. We show that Drosophila FMRP (dFMR1) is required for long-term olfactory habituation (LTH), a phenomenon dependent on Atx2-dependent potentiation of inhibitory transmission from local interneurons (LNs) to projection neurons (PNs) in the antennal lobe. dFMR1 is also required for LTH-associated depression of odor-evoked calcium transients in PNs. Strong transdominant genetic interactions among dFMR1, atx2, the deadbox helicase me31B, and argonaute1 (ago1) mutants, as well as coimmunoprecitation of dFMR1 with Atx2, indicate that dFMR1 and Atx2 function together in a microRNA-dependent process necessary for LTH. Consistently, PN or LN knockdown of dFMR1, Atx2, Me31B, or the miRNA-pathway protein GW182 increases expression of a Ca2+/calmodulin-dependent protein kinase II (CaMKII) translational reporter. Moreover, brain immunoprecipitates of dFMR1 and Atx2 proteins include CaMKII mRNA, indicating respective physical interactions with this mRNA. Because CaMKII is necessary for LTH, these data indicate that fragile X mental retardation protein and Atx2 act via at least one common target RNA for memory-associated long-term synaptic plasticity. The observed requirement in LNs and PNs supports an emerging view that both presynaptic and postsynaptic translation are necessary for long-term synaptic plasticity. However, whereas Atx2 is necessary for the integrity of dendritic and somatic Me31B-containing particles, dFmr1 is not. Together, these data indicate that dFmr1 and Atx2 function in long-term but not short-term memory, regulating translation of at least some common presynaptic and postsynaptic target mRNAs in the same cells.
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Na D, Rouf M, O'Kane CJ, Rubinsztein DC, Gsponer J. NeuroGeM, a knowledgebase of genetic modifiers in neurodegenerative diseases. BMC Med Genomics 2013; 6:52. [PMID: 24229347 PMCID: PMC3833180 DOI: 10.1186/1755-8794-6-52] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 11/08/2013] [Indexed: 11/26/2022] Open
Abstract
Background Neurodegenerative diseases (NDs) are characterized by the progressive loss of neurons in the human brain. Although the majority of NDs are sporadic, evidence is accumulating that they have a strong genetic component. Therefore, significant efforts have been made in recent years to not only identify disease-causing genes but also genes that modify the severity of NDs, so-called genetic modifiers. To date there exists no compendium that lists and cross-links genetic modifiers of different NDs. Description In order to address this need, we present NeuroGeM, the first comprehensive knowledgebase providing integrated information on genetic modifiers of nine different NDs in the model organisms D. melanogaster, C. elegans, and S. cerevisiae. NeuroGeM cross-links curated genetic modifier information from the different NDs and provides details on experimental conditions used for modifier identification, functional annotations, links to homologous proteins and color-coded protein-protein interaction networks to visualize modifier interactions. We demonstrate how this database can be used to generate new understanding through meta-analysis. For instance, we reveal that the Drosophila genes DnaJ-1, thread, Atx2, and mub are generic modifiers that affect multiple if not all NDs. Conclusion As the first compendium of genetic modifiers, NeuroGeM will assist experimental and computational scientists in their search for the pathophysiological mechanisms underlying NDs. http://chibi.ubc.ca/neurogem.
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Affiliation(s)
| | | | | | | | - Jörg Gsponer
- Department of Biochemistry and Molecular Biology, Centre for High-throughput Biology, University of British Columbia, 2125 East Mall, Vancouver, BC V6T 1Z4, Canada.
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Drost J, Nonis D, Eich F, Leske O, Damrath E, Brunt ER, Lastres-Becker I, Heumann R, Nowock J, Auburger G. Ataxin-2 modulates the levels of Grb2 and SRC but not ras signaling. J Mol Neurosci 2013; 51:68-81. [PMID: 23335000 PMCID: PMC3739869 DOI: 10.1007/s12031-012-9949-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 12/28/2012] [Indexed: 12/13/2022]
Abstract
Ataxin-2 (ATXN2) is implicated mainly in mRNA processing. Some ATXN2 associates with receptor tyrosine kinases (RTK), inhibiting their endocytic internalization through interaction of proline-rich domains (PRD) in ATXN2 with SH3 motifs in Src. Gain of function of ATXN2 leads to neuronal atrophy in the diseases spinocerebellar ataxia type 2 (SCA2) and amyotrophic lateral sclerosis (ALS). Conversely, ATXN2 knockout (KO) mice show hypertrophy and insulin resistance. To elucidate the influence of ATXN2 on trophic regulation, we surveyed interactions of ATXN2 with SH3 motifs from numerous proteins and observed a novel interaction with Grb2. Direct binding in glutathione S-transferase (GST) pull-down assays and coimmunoprecipitation of the endogenous proteins indicated a physiologically relevant association. In SCA2 patient fibroblasts, Grb2 more than Src protein levels were diminished, with an upregulation of both transcripts suggesting enhanced protein turnover. In KO mouse embryonal fibroblasts (MEF), the protein levels of Grb2 and Src were decreased. ATXN2 absence by itself was insufficient to significantly change Grb2-dependent signaling for endogenous Ras levels, Ras-GTP levels, and kinetics as well as MEK1 phosphorylation, suggesting that other factors compensate for proliferation control. In KO tissue with postmitotic neurons, a significant decrease of Src protein levels is prominent rather than Grb2. ATXN2 mutations modulate the levels of several components of the RTK endocytosis complex and may thus contribute to alter cell proliferation as well as translation and growth.
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Affiliation(s)
- Jessica Drost
- Section Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd Floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - David Nonis
- Section Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd Floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
- Present Address: Department of Reproductive Medicine, University of California at San Diego, School of Medicine, 9500 Gilman Dr., La Jolla, CA 92093-0633 USA
| | - Florian Eich
- Section Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd Floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Oliver Leske
- Department Molecular Neurobiochemistry, Faculty for Chemistry and Biochemistry, Ruhr-University Bochum, Universitätsstraβe 150, 44780 Bochum, Germany
| | - Ewa Damrath
- Section Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd Floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Ewout R. Brunt
- Department of Neurology, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, 9713 RB Groningen, The Netherlands
| | - Isabel Lastres-Becker
- Section Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd Floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
- Present Address: Departamento de Bioquímica, Instituto de Investigaciones Biomédicas “Alberto Sols”, and Centro de Investigación en Red en Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Rolf Heumann
- Department Molecular Neurobiochemistry, Faculty for Chemistry and Biochemistry, Ruhr-University Bochum, Universitätsstraβe 150, 44780 Bochum, Germany
| | - Joachim Nowock
- Section Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd Floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Georg Auburger
- Section Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd Floor, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
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Genetic circuitry of Survival motor neuron, the gene underlying spinal muscular atrophy. Proc Natl Acad Sci U S A 2013; 110:E2371-80. [PMID: 23757500 DOI: 10.1073/pnas.1301738110] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The clinical severity of the neurodegenerative disorder spinal muscular atrophy (SMA) is dependent on the levels of functional Survival Motor Neuron (SMN) protein. Consequently, current strategies for developing treatments for SMA generally focus on augmenting SMN levels. To identify additional potential therapeutic avenues and achieve a greater understanding of SMN, we applied in vivo, in vitro, and in silico approaches to identify genetic and biochemical interactors of the Drosophila SMN homolog. We identified more than 300 candidate genes that alter an Smn-dependent phenotype in vivo. Integrating the results from our genetic screens, large-scale protein interaction studies, and bioinformatic analysis, we define a unique interactome for SMN that provides a knowledge base for a better understanding of SMA.
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RAS-MAPK-MSK1 pathway modulates ataxin 1 protein levels and toxicity in SCA1. Nature 2013; 498:325-331. [PMID: 23719381 DOI: 10.1038/nature12204] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 04/19/2013] [Indexed: 12/14/2022]
Abstract
Many neurodegenerative disorders, such as Alzheimer's, Parkinson's and polyglutamine diseases, share a common pathogenic mechanism: the abnormal accumulation of disease-causing proteins, due to either the mutant protein's resistance to degradation or overexpression of the wild-type protein. We have developed a strategy to identify therapeutic entry points for such neurodegenerative disorders by screening for genetic networks that influence the levels of disease-driving proteins. We applied this approach, which integrates parallel cell-based and Drosophila genetic screens, to spinocerebellar ataxia type 1 (SCA1), a disease caused by expansion of a polyglutamine tract in ataxin 1 (ATXN1). Our approach revealed that downregulation of several components of the RAS-MAPK-MSK1 pathway decreases ATXN1 levels and suppresses neurodegeneration in Drosophila and mice. Importantly, pharmacological inhibitors of components of this pathway also decrease ATXN1 levels, suggesting that these components represent new therapeutic targets in mitigating SCA1. Collectively, these data reveal new therapeutic entry points for SCA1 and provide a proof-of-principle for tackling other classes of intractable neurodegenerative diseases.
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Rüb U, Schöls L, Paulson H, Auburger G, Kermer P, Jen JC, Seidel K, Korf HW, Deller T. Clinical features, neurogenetics and neuropathology of the polyglutamine spinocerebellar ataxias type 1, 2, 3, 6 and 7. Prog Neurobiol 2013; 104:38-66. [PMID: 23438480 DOI: 10.1016/j.pneurobio.2013.01.001] [Citation(s) in RCA: 234] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 01/22/2013] [Accepted: 01/31/2013] [Indexed: 12/18/2022]
Abstract
The spinocerebellar ataxias type 1 (SCA1), 2 (SCA2), 3 (SCA3), 6 (SCA6) and 7 (SCA7) are genetically defined autosomal dominantly inherited progressive cerebellar ataxias (ADCAs). They belong to the group of CAG-repeat or polyglutamine diseases and share pathologically expanded and meiotically unstable glutamine-encoding CAG-repeats at distinct gene loci encoding elongated polyglutamine stretches in the disease proteins. In recent years, progress has been made in the understanding of the pathogenesis of these currently incurable diseases: Identification of underlying genetic mechanisms made it possible to classify the different ADCAs and to define their clinical and pathological features. Furthermore, advances in molecular biology yielded new insights into the physiological and pathophysiological role of the gene products of SCA1, SCA2, SCA3, SCA6 and SCA7 (i.e. ataxin-1, ataxin-2, ataxin-3, α-1A subunit of the P/Q type voltage-dependent calcium channel, ataxin-7). In the present review we summarize our current knowledge about the polyglutamine ataxias SCA1, SCA2, SCA3, SCA6 and SCA7 and compare their clinical and electrophysiological features, genetic and molecular biological background, as well as their brain pathologies. Furthermore, we provide an overview of the structure, interactions and functions of the different disease proteins. On the basis of these comprehensive data, similarities, differences and possible disease mechanisms are discussed.
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Affiliation(s)
- Udo Rüb
- Dr. Senckenberg Chronomedical Institute, Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt/Main, Germany.
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Camero S, Benítez MJ, Jiménez JS. Anomalous Protein–DNA Interactions Behind Neurological Disorders. PROTEIN-NUCLEIC ACIDS INTERACTIONS 2013; 91:37-63. [DOI: 10.1016/b978-0-12-411637-5.00002-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Miller JP, Yates BE, Al-Ramahi I, Berman AE, Sanhueza M, Kim E, de Haro M, DeGiacomo F, Torcassi C, Holcomb J, Gafni J, Mooney SD, Botas J, Ellerby LM, Hughes RE. A genome-scale RNA-interference screen identifies RRAS signaling as a pathologic feature of Huntington's disease. PLoS Genet 2012; 8:e1003042. [PMID: 23209424 PMCID: PMC3510027 DOI: 10.1371/journal.pgen.1003042] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 08/29/2012] [Indexed: 11/19/2022] Open
Abstract
A genome-scale RNAi screen was performed in a mammalian cell-based assay to identify modifiers of mutant huntingtin toxicity. Ontology analysis of suppressor data identified processes previously implicated in Huntington's disease, including proteolysis, glutamate excitotoxicity, and mitochondrial dysfunction. In addition to established mechanisms, the screen identified multiple components of the RRAS signaling pathway as loss-of-function suppressors of mutant huntingtin toxicity in human and mouse cell models. Loss-of-function in orthologous RRAS pathway members also suppressed motor dysfunction in a Drosophila model of Huntington's disease. Abnormal activation of RRAS and a down-stream effector, RAF1, was observed in cellular models and a mouse model of Huntington's disease. We also observe co-localization of RRAS and mutant huntingtin in cells and in mouse striatum, suggesting that activation of R-Ras may occur through protein interaction. These data indicate that mutant huntingtin exerts a pathogenic effect on this pathway that can be corrected at multiple intervention points including RRAS, FNTA/B, PIN1, and PLK1. Consistent with these results, chemical inhibition of farnesyltransferase can also suppress mutant huntingtin toxicity. These data suggest that pharmacological inhibition of RRAS signaling may confer therapeutic benefit in Huntington's disease.
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Affiliation(s)
- John P. Miller
- The Buck Institute for Research on Aging, Novato, California, United States of America
| | - Bridget E. Yates
- The Buck Institute for Research on Aging, Novato, California, United States of America
| | - Ismael Al-Ramahi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ari E. Berman
- The Buck Institute for Research on Aging, Novato, California, United States of America
| | - Mario Sanhueza
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Eugene Kim
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Maria de Haro
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Francesco DeGiacomo
- The Buck Institute for Research on Aging, Novato, California, United States of America
| | - Cameron Torcassi
- The Buck Institute for Research on Aging, Novato, California, United States of America
| | - Jennifer Holcomb
- The Buck Institute for Research on Aging, Novato, California, United States of America
| | - Juliette Gafni
- The Buck Institute for Research on Aging, Novato, California, United States of America
| | - Sean D. Mooney
- The Buck Institute for Research on Aging, Novato, California, United States of America
| | - Juan Botas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lisa M. Ellerby
- The Buck Institute for Research on Aging, Novato, California, United States of America
- * E-mail: (LME); (REH)
| | - Robert E. Hughes
- The Buck Institute for Research on Aging, Novato, California, United States of America
- * E-mail: (LME); (REH)
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Damrath E, Heck MV, Gispert S, Azizov M, Nowock J, Seifried C, Rüb U, Walter M, Auburger G. ATXN2-CAG42 sequesters PABPC1 into insolubility and induces FBXW8 in cerebellum of old ataxic knock-in mice. PLoS Genet 2012; 8:e1002920. [PMID: 22956915 PMCID: PMC3431311 DOI: 10.1371/journal.pgen.1002920] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Accepted: 07/10/2012] [Indexed: 12/15/2022] Open
Abstract
Spinocerebellar Ataxia Type 2 (SCA2) is caused by expansion of a polyglutamine encoding triplet repeat in the human ATXN2 gene beyond (CAG)31. This is thought to mediate toxic gain-of-function by protein aggregation and to affect RNA processing, resulting in degenerative processes affecting preferentially cerebellar neurons. As a faithful animal model, we generated a knock-in mouse replacing the single CAG of murine Atxn2 with CAG42, a frequent patient genotype. This expansion size was inherited stably. The mice showed phenotypes with reduced weight and later motor incoordination. Although brain Atxn2 mRNA became elevated, soluble ATXN2 protein levels diminished over time, which might explain partial loss-of-function effects. Deficits in soluble ATXN2 protein correlated with the appearance of insoluble ATXN2, a progressive feature in cerebellum possibly reflecting toxic gains-of-function. Since in vitro ATXN2 overexpression was known to reduce levels of its protein interactor PABPC1, we studied expansion effects on PABPC1. In cortex, PABPC1 transcript and soluble and insoluble protein levels were increased. In the more vulnerable cerebellum, the progressive insolubility of PABPC1 was accompanied by decreased soluble protein levels, with PABPC1 mRNA showing no compensatory increase. The sequestration of PABPC1 into insolubility by ATXN2 function gains was validated in human cell culture. To understand consequences on mRNA processing, transcriptome profiles at medium and old age in three different tissues were studied and demonstrated a selective induction of Fbxw8 in the old cerebellum. Fbxw8 is encoded next to the Atxn2 locus and was shown in vitro to decrease the level of expanded insoluble ATXN2 protein. In conclusion, our data support the concept that expanded ATXN2 undergoes progressive insolubility and affects PABPC1 by a toxic gain-of-function mechanism with tissue-specific effects, which may be partially alleviated by the induction of FBXW8. Frequent age-associated neurodegenerative disorders like Alzheimer's, Parkinson's, and Lou Gehrig's disease are being elucidated molecularly by studying rare heritable variants. Various hereditary neurodegenerative disorders are caused by polyglutamine expansions in different proteins. In spite of this common pathogenesis and the pathological aggregation of most affected proteins, investigators were puzzled that the pattern of affected neuron population varies and that molecular mechanisms seem different between such disorders. The polyglutamine expansions in the Ataxin-2 (ATXN2) protein are exceptional in view of the lack of aggregate clumps in nuclei of affected Purkinje neurons and well documented alterations of RNA processing in the resulting disorders SCA2 and ALS. Here, as a faithful disease model and to overcome the unavailability of autopsied patient brain tissues, we generated and characterized an ATXN2-CAG42-knock-in mouse mutant. Our data show that the unspecific, chronically present mutation leads to progressive insolubility and to reduced soluble levels of the disease protein and of an interactor protein, which modulates RNA processing. Compensatory efforts are particularly weak in vulnerable tissue. They appear to include the increased degradation of the toxic disease protein by FBXW8. Thus the link between protein and RNA pathology becomes clear, and crucial molecular targets for preventive therapy are identified.
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Affiliation(s)
- Ewa Damrath
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Frankfurt am Main, Germany
| | - Melanie V. Heck
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Frankfurt am Main, Germany
| | - Suzana Gispert
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Frankfurt am Main, Germany
| | - Mekhman Azizov
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Frankfurt am Main, Germany
| | - Joachim Nowock
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Frankfurt am Main, Germany
| | - Carola Seifried
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Frankfurt am Main, Germany
| | - Udo Rüb
- Department of Clinical Neuroanatomy, Dr. Senckenbergisches Chronomedizinisches Institut, Goethe University Medical School, Frankfurt am Main, Germany
| | - Michael Walter
- Institute of Medical Genetics, Eberhard Karls University, Tübingen, Germany
| | - Georg Auburger
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Frankfurt am Main, Germany
- * E-mail:
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Rincon-Limas DE, Jensen K, Fernandez-Funez P. Drosophila models of proteinopathies: the little fly that could. Curr Pharm Des 2012; 18:1108-22. [PMID: 22288402 PMCID: PMC3290773 DOI: 10.2174/138161212799315894] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Accepted: 12/19/2011] [Indexed: 02/08/2023]
Abstract
Alzheimer’s, Parkinson’s, and Huntington’s disease are complex neurodegenerative conditions with high prevalence characterized by protein misfolding and deposition in the brain. Considerable progress has been made in the last two decades in identifying the genes and proteins responsible for several human ‘proteinopathies’. A wide variety of wild type and mutant proteins associated with neurodegenerative conditions are structurally unstable, misfolded, and acquire conformations rich in ß-sheets (ß-state). These conformers form highly toxic self-assemblies that kill the neurons in stereotypical patterns. Unfortunately, the detailed understanding of the molecular and cellular perturbations caused by these proteins has not produced a single disease-modifying therapy. More than a decade ago, several groups demonstrated that human proteinopathies reproduce critical features of the disease in transgenic flies, including protein misfolding, aggregation, and neurotoxicity. These initial reports led to an explosion of research that has contributed to a better understanding of the molecular mechanisms regulating conformational dynamics and neurotoxic cascades. To remain relevant in this competitive environment, Drosophila models will need to expand their flexible, innovative, and multidisciplinary approaches to find new discoveries and translational applications.
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Affiliation(s)
- Diego E Rincon-Limas
- Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, FL 32610-0236, USA.
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