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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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Wang JY, Liu YJ, Zhang XL, Liu YH, Jiang LL, Hu HY. PolyQ-expanded ataxin-2 aggregation impairs cellular processing-body homeostasis via sequestering the RNA helicase DDX6. J Biol Chem 2024:107413. [PMID: 38810698 DOI: 10.1016/j.jbc.2024.107413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 04/02/2024] [Accepted: 04/10/2024] [Indexed: 05/31/2024] Open
Abstract
Ataxin-2 (Atx2) is a polyglutamine (polyQ) tract-containing RNA-binding protein, while its polyQ expansion may cause protein aggregation that is implicated in the pathogenesis of neurodegenerative diseases such as spinocerebellar ataxia type 2 (SCA2). However, the molecular mechanism underlying how Atx2 aggregation contributes to the proteinopathies remains elusive. Here, we investigated the influence of Atx2 aggregation on the assembly and functionality of cellular processing bodies (P-bodies) by using biochemical and fluorescence imaging approaches. We have revealed that polyQ-expanded (PQE) Atx2 sequesters the DEAD-box RNA helicase (DDX6), an essential component of P-bodies, into aggregates or puncta via some RNA sequences. The N-terminal like-Sm (LSm) domain of Atx2 (residues 82-184) and the C-terminal helicase domain of DDX6 are responsible for the interaction and specific sequestration. Moreover, sequestration of DDX6 may aggravate pre-mRNA mis-splicing, and interfere with the assembly of cellular P-bodies, releasing the endoribonuclease MARF1 that promotes mRNA decay and translational repression. Rescuing the DDX6 protein level can recover the assembly and functionality of P-bodies preventing targeted mRNA from degradation. This study provides a line of evidence for sequestration of the P-body components and impairment of the P-body homeostasis in dysregulating RNA metabolism, which is implicated in the disease pathologies and a potential therapeutic target.
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Affiliation(s)
- Jian-Yang Wang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, P. R. China; University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Ya-Jun Liu
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, P. R. China; University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xiang-Le Zhang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, P. R. China; University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Yin-Hu Liu
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, P. R. China; University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Lei-Lei Jiang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, P. R. China
| | - Hong-Yu Hu
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, P. R. China.
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3
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Liu YJ, Wang JY, Zhang XL, Jiang LL, Hu HY. Ataxin-2 sequesters Raptor into aggregates and impairs cellular mTORC1 signaling. FEBS J 2024; 291:1795-1812. [PMID: 38308810 DOI: 10.1111/febs.17081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 11/28/2023] [Accepted: 01/26/2024] [Indexed: 02/05/2024]
Abstract
Ataxin-2 (Atx2) is a polyglutamine (polyQ) protein, in which abnormal expansion of the polyQ tract can trigger protein aggregation and consequently cause spinocerebellar ataxia type 2 (SCA2), but the mechanism underlying how Atx2 aggregation leads to proteinopathy remains elusive. Here, we investigate the molecular mechanism and cellular consequences of Atx2 aggregation by molecular cell biology approaches. We have revealed that either normal or polyQ-expanded Atx2 can sequester Raptor, a component of mammalian target of rapamycin complex 1 (mTORC1), into aggregates based on their specific interaction. Further research indicates that the polyQ tract and the N-terminal region (residues 1-784) of Atx2 are responsible for the specific sequestration. Moreover, this sequestration leads to suppression of the mTORC1 activity as represented by down-regulation of phosphorylated P70S6K, which can be reversed by overexpression of Raptor. As mTORC1 is a key regulator of autophagy, Atx2 aggregation and sequestration also induces autophagy by upregulating LC3-II and reducing phosphorylated ULK1 levels. This study proposes that Atx2 sequesters Raptor into aggregates, thereby impairing cellular mTORC1 signaling and inducing autophagy, and will be beneficial for a better understanding of the pathogenesis of SCA2 and other polyQ diseases.
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Affiliation(s)
- Ya-Jun Liu
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jian-Yang Wang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiang-Le Zhang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Lei-Lei Jiang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Hong-Yu Hu
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
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Perlegos AE, Durkin J, Belfer SJ, Rodriguez A, Shcherbakova O, Park K, Luong J, Bonini NM, Kayser MS. TDP-43 impairs sleep in Drosophila through Ataxin-2-dependent metabolic disturbance. SCIENCE ADVANCES 2024; 10:eadj4457. [PMID: 38198547 PMCID: PMC10780954 DOI: 10.1126/sciadv.adj4457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 12/12/2023] [Indexed: 01/12/2024]
Abstract
Neurodegenerative diseases such as amyotrophic lateral sclerosis and frontotemporal dementia are associated with substantial sleep disruption, which may accelerate cognitive decline and brain degeneration. Here, we define a role for trans-activation response element (TAR) DNA binding protein 43 (TDP-43), a protein associated with human neurodegenerative disease, in regulating sleep using Drosophila. Expression of TDP-43 severely disrupts sleep, and the sleep deficit is rescued by Atx2 knockdown. Brain RNA sequencing revealed that Atx2 RNA interference regulates transcripts enriched for small-molecule metabolic signaling in TDP-43 brains. Focusing on these Atx2-regulated genes, we identified suppressors of the TDP-43 sleep phenotype enriched for metabolism pathways. Knockdown of Atx2 or treatment with rapamycin attenuated the sleep phenotype and mitigated the disruption of small-molecule glycogen metabolism caused by TDP-43. Our findings provide a connection between toxicity of TDP-43 and sleep disturbances and highlight key aspects of metabolism that interplay with TDP-43 toxicity upon Atx2 rescue.
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Affiliation(s)
- Alexandra E. Perlegos
- Neuroscience Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jaclyn Durkin
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- National Institute of Neurological Disorders & Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Samuel J. Belfer
- Neuroscience Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anyara Rodriguez
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Oksana Shcherbakova
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kristen Park
- Neuroscience Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jenny Luong
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nancy M. Bonini
- Neuroscience Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Matthew S. Kayser
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Chronobiology Sleep Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
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5
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Chitre M, Emery P. ATXN2 is a target of N-terminal proteolysis. PLoS One 2023; 18:e0296085. [PMID: 38128014 PMCID: PMC10735043 DOI: 10.1371/journal.pone.0296085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 12/04/2023] [Indexed: 12/23/2023] Open
Abstract
Spinocerebellar ataxia 2 (SCA2) is a neurodegenerative disorder caused by the expansion of the poly-glutamine (polyQ) tract of Ataxin-2 (ATXN2). Other polyQ-containing proteins such as ATXN7 and huntingtin are associated with the development of neurodegenerative diseases when their N-terminal polyQ domains are expanded. Furthermore, they undergo proteolytic processing events that produce N-terminal fragments that include the polyQ stretch, which are implicated in pathogenesis. Interestingly, N-terminal ATXN2 fragments were reported in a brain extract from a SCA2 patient, but it is currently unknown whether an expanded polyQ domain contributes to ATXN2 proteolytic susceptibility. Here, we used transient expression in HEK293 cells to determine whether ATXN2 is a target for specific N-terminal proteolysis. We found that ATXN2 proteins with either normal or expanded polyQ stretches undergo proteolytic cleavage releasing an N-terminal polyQ-containing fragment. We identified a short amino acid sequence downstream of the polyQ domain that is necessary for N-terminal cleavage of full-length ATXN2 and sufficient to induce proteolysis of a heterologous protein. However, this sequence is not required for cleavage of a short ATXN2 isoform produced from an alternative start codon located just upstream of the CAG repeats encoding the polyQ domain. Our study extends our understanding of ATXN2 posttranslational regulation by revealing that this protein can be the target of specific proteolytic cleavage events releasing polyQ-containing products that are modulated by the N-terminal domain of ATXN2. N-terminal ATXN2 proteolysis of expanded polyQ domains might contribute to SCA2 pathology, as observed in other neurodegenerative disorders caused by polyQ domain expansion.
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Affiliation(s)
- Monika Chitre
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Patrick Emery
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
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6
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Boeynaems S, Dorone Y, Zhuang Y, Shabardina V, Huang G, Marian A, Kim G, Sanyal A, Şen NE, Griffith D, Docampo R, Lasker K, Ruiz-Trillo I, Auburger G, Holehouse AS, Kabashi E, Lin Y, Gitler AD. Poly(A)-binding protein is an ataxin-2 chaperone that regulates biomolecular condensates. Mol Cell 2023; 83:2020-2034.e6. [PMID: 37295429 PMCID: PMC10318123 DOI: 10.1016/j.molcel.2023.05.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 03/14/2023] [Accepted: 05/17/2023] [Indexed: 06/12/2023]
Abstract
Biomolecular condensation underlies the biogenesis of an expanding array of membraneless assemblies, including stress granules (SGs), which form under a variety of cellular stresses. Advances have been made in understanding the molecular grammar of a few scaffold proteins that make up these phases, but how the partitioning of hundreds of SG proteins is regulated remains largely unresolved. While investigating the rules that govern the condensation of ataxin-2, an SG protein implicated in neurodegenerative disease, we unexpectedly identified a short 14 aa sequence that acts as a condensation switch and is conserved across the eukaryote lineage. We identify poly(A)-binding proteins as unconventional RNA-dependent chaperones that control this regulatory switch. Our results uncover a hierarchy of cis and trans interactions that fine-tune ataxin-2 condensation and reveal an unexpected molecular function for ancient poly(A)-binding proteins as regulators of biomolecular condensate proteins. These findings may inspire approaches to therapeutically target aberrant phases in disease.
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Affiliation(s)
- Steven Boeynaems
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Therapeutic Innovation Center (THINC), Baylor College of Medicine, Houston, TX 77030, USA; Center for Alzheimer's and Neurodegenerative Diseases (CAND), Texas Children's Hospital, Houston, TX 77030, USA; Dan L Duncan Comprehensive Cancer Center (DLDCCC), Baylor College of Medicine, Houston, TX 77030, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA.
| | - Yanniv Dorone
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Yanrong Zhuang
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Centre for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Victoria Shabardina
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37-49, Barcelona 08003 Catalonia, Spain
| | - Guozhong Huang
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Anca Marian
- Imagine Institute, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1163, Paris Descartes Université, 75015 Paris, France
| | - Garam Kim
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Anushka Sanyal
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Nesli-Ece Şen
- Experimental Neurology, Goethe-University Hospital, 60590 Frankfurt, Germany
| | - Daniel Griffith
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for Biomolecular Condensates, Washington University in St Louis, St. Louis, MO 63130, USA
| | - Roberto Docampo
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Keren Lasker
- The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Iñaki Ruiz-Trillo
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37-49, Barcelona 08003 Catalonia, Spain; ICREA, Passeig Lluís Companys 23, Barcelona 08010 Catalonia, Spain
| | - Georg Auburger
- Experimental Neurology, Goethe-University Hospital, 60590 Frankfurt, Germany
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for Biomolecular Condensates, Washington University in St Louis, St. Louis, MO 63130, USA
| | - Edor Kabashi
- Imagine Institute, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1163, Paris Descartes Université, 75015 Paris, France
| | - Yi Lin
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Centre for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Aaron D Gitler
- Department of Genetics, Stanford University, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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7
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Koppenol R, Conceição A, Afonso IT, Afonso-Reis R, Costa RG, Tomé S, Teixeira D, da Silva JP, Côdesso JM, Brito DVC, Mendonça L, Marcelo A, Pereira de Almeida L, Matos CA, Nóbrega C. The stress granule protein G3BP1 alleviates spinocerebellar ataxia-associated deficits. Brain 2023; 146:2346-2363. [PMID: 36511898 PMCID: PMC10232246 DOI: 10.1093/brain/awac473] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 11/04/2022] [Accepted: 11/25/2022] [Indexed: 09/09/2023] Open
Abstract
Polyglutamine diseases are a group of neurodegenerative disorders caused by an abnormal expansion of CAG repeat tracts in the codifying regions of nine, otherwise unrelated, genes. While the protein products of these genes are suggested to play diverse cellular roles, the pathogenic mutant proteins bearing an expanded polyglutamine sequence share a tendency to self-assemble, aggregate and engage in abnormal molecular interactions. Understanding the shared paths that link polyglutamine protein expansion to the nervous system dysfunction and the degeneration that takes place in these disorders is instrumental to the identification of targets for therapeutic intervention. Among polyglutamine diseases, spinocerebellar ataxias (SCAs) share many common aspects, including the fact that they involve dysfunction of the cerebellum, resulting in ataxia. Our work aimed at exploring a putative new therapeutic target for the two forms of SCA with higher worldwide prevalence, SCA type 2 (SCA2) and type 3 (SCA3), which are caused by expanded forms of ataxin-2 (ATXN2) and ataxin-3 (ATXN3), respectively. The pathophysiology of polyglutamine diseases has been described to involve an inability to properly respond to cell stress. We evaluated the ability of GTPase-activating protein-binding protein 1 (G3BP1), an RNA-binding protein involved in RNA metabolism regulation and stress responses, to counteract SCA2 and SCA3 pathology, using both in vitro and in vivo disease models. Our results indicate that G3BP1 overexpression in cell models leads to a reduction of ATXN2 and ATXN3 aggregation, associated with a decrease in protein expression. This protective effect of G3BP1 against polyglutamine protein aggregation was reinforced by the fact that silencing G3bp1 in the mouse brain increases human expanded ATXN2 and ATXN3 aggregation. Moreover, a decrease of G3BP1 levels was detected in cells derived from patients with SCA2 and SCA3, suggesting that G3BP1 function is compromised in the context of these diseases. In lentiviral mouse models of SCA2 and SCA3, G3BP1 overexpression not only decreased protein aggregation but also contributed to the preservation of neuronal cells. Finally, in an SCA3 transgenic mouse model with a severe ataxic phenotype, G3BP1 lentiviral delivery to the cerebellum led to amelioration of several motor behavioural deficits. Overall, our results indicate that a decrease in G3BP1 levels may be a contributing factor to SCA2 and SCA3 pathophysiology, and that administration of this protein through viral vector-mediated delivery may constitute a putative approach to therapy for these diseases, and possibly other polyglutamine disorders.
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Affiliation(s)
- Rebekah Koppenol
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
- PhD Program in Biomedial Sciences, Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-504 Coimbra, Portugal
| | - André Conceição
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
- PhD Program in Biomedial Sciences, Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
| | - Inês T Afonso
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
| | - Ricardo Afonso-Reis
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
| | - Rafael G Costa
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
| | - Sandra Tomé
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-504 Coimbra, Portugal
| | - Diogo Teixeira
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
| | | | - José Miguel Côdesso
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
- PhD Program in Biomedial Sciences, Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-504 Coimbra, Portugal
| | - David V C Brito
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
| | - Liliana Mendonça
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-504 Coimbra, Portugal
| | - Adriana Marcelo
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-504 Coimbra, Portugal
| | - Luís Pereira de Almeida
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, 3004-504 Coimbra, Portugal
- Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Carlos A Matos
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
| | - Clévio Nóbrega
- ABC-RI, Algarve Biomedical Center Research Institute, 8005-139 Faro, Portugal
- Faculdade de Medicina e Ciências Biomédicas, Universidade do Algarve, 8005-139 Faro, Portugal
- Champalimaud Research Program, Champalimaud Center for the Unknown, 1400-038 Lisbon, Portugal
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8
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Granata S, Mercuri S, Troise D, Gesualdo L, Stallone G, Zaza G. mTOR-inhibitors and post-transplant diabetes mellitus: a link still debated in kidney transplantation. Front Med (Lausanne) 2023; 10:1168967. [PMID: 37250653 PMCID: PMC10213242 DOI: 10.3389/fmed.2023.1168967] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Accepted: 04/25/2023] [Indexed: 05/31/2023] Open
Abstract
The mammalian target of rapamycin inhibitors (mTOR-Is, Sirolimus, and Everolimus) are immunosuppressive drugs widely employed in kidney transplantation. Their main mechanism of action includes the inhibition of a serine/threonine kinase with a pivotal role in cellular metabolism and in various eukaryotic biological functions (including proteins and lipids synthesis, autophagy, cell survival, cytoskeleton organization, lipogenesis, and gluconeogenesis). Moreover, as well described, the inhibition of the mTOR pathway may also contribute to the development of the post-transplant diabetes mellitus (PTDM), a major clinical complication that may dramatically impact allograft survival (by accelerating the development of the chronic allograft damage) and increase the risk of severe systemic comorbidities. Several factors may contribute to this condition, but the reduction of the beta-cell mass, the impairment of the insulin secretion and resistance, and the induction of glucose intolerance may play a pivotal role. However, although the results of several in vitro and in animal models, the real impact of mTOR-Is on PTDM is still debated and the entire biological machinery is poorly recognized. Therefore, to better elucidate the impact of the mTOR-Is on the risk of PTDM in kidney transplant recipients and to potentially uncover future research topics (particularly for the clinical translational research), we decided to review the available literature evidence regarding this important clinical association. In our opinion, based on the published reports, we cannot draw any conclusion and PTDM remains a challenge. However, also in this case, the administration of the lowest possible dose of mTOR-I should also be recommended.
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Affiliation(s)
- Simona Granata
- Nephrology, Dialysis and Transplantation Unit, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Silvia Mercuri
- Nephrology, Dialysis and Transplantation Unit, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Dario Troise
- Nephrology, Dialysis and Transplantation Unit, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Loreto Gesualdo
- Renal, Dialysis and Transplantation Unit, Department of Precision and Regenerative Medicine and Ionian Area (DIMEPRE-J), University of Bari, Bari, Italy
| | - Giovanni Stallone
- Nephrology, Dialysis and Transplantation Unit, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Gianluigi Zaza
- Nephrology, Dialysis and Transplantation Unit, Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
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9
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Turner M. Regulation and function of poised mRNAs in lymphocytes. Bioessays 2023; 45:e2200236. [PMID: 37009769 DOI: 10.1002/bies.202200236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 02/15/2023] [Accepted: 02/17/2023] [Indexed: 04/04/2023]
Abstract
Pre-existing but untranslated or 'poised' mRNA exists as a means to rapidly induce the production of specific proteins in response to stimuli and as a safeguard to limit the actions of these proteins. The translation of poised mRNA enables immune cells to express quickly genes that enhance immune responses. The molecular mechanisms that repress the translation of poised mRNA and, upon stimulation, enable translation have yet to be elucidated. They likely reflect intrinsic properties of the mRNAs and their interactions with trans-acting factors that direct poised mRNAs away from or into the ribosome. Here, I discuss mechanisms by which this might be regulated.
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Affiliation(s)
- Martin Turner
- Immunology Programme, The Babraham Institute, Cambridge, UK
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10
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TR-FRET-Based Immunoassay to Measure Ataxin-2 as a Target Engagement Marker in Spinocerebellar Ataxia Type 2. Mol Neurobiol 2023; 60:3553-3567. [PMID: 36894829 PMCID: PMC10122633 DOI: 10.1007/s12035-023-03294-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 02/22/2023] [Indexed: 03/11/2023]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominantly inherited neurodegenerative disease, which belongs to the trinucleotide repeat disease group with a CAG repeat expansion in exon 1 of the ATXN2 gene resulting in an ataxin-2 protein with an expanded polyglutamine (polyQ)-stretch. The disease is late manifesting leading to early death. Today, therapeutic interventions to cure the disease or even to decelerate disease progression are not available yet. Furthermore, primary readout parameter for disease progression and therapeutic intervention studies are limited. Thus, there is an urgent need for quantifiable molecular biomarkers such as ataxin-2 becoming even more important due to numerous potential protein-lowering therapeutic intervention strategies. The aim of this study was to establish a sensitive technique to measure the amount of soluble polyQ-expanded ataxin-2 in human biofluids to evaluate ataxin-2 protein levels as prognostic and/or therapeutic biomarker in SCA2. Time-resolved fluorescence energy transfer (TR-FRET) was used to establish a polyQ-expanded ataxin-2-specific immunoassay. Two different ataxin-2 antibodies and two different polyQ-binding antibodies were validated in three different concentrations and tested in cellular and animal tissue as well as in human cell lines, comparing different buffer conditions to evaluate the best assay conditions. We established a TR-FRET-based immunoassay for soluble polyQ-expanded ataxin-2 and validated measurements in human cell lines including iPSC-derived cortical neurons. Additionally, our immunoassay was sensitive enough to monitor small ataxin-2 expression changes by siRNA or starvation treatment. We successfully established the first sensitive ataxin-2 immunoassay to measure specifically soluble polyQ-expanded ataxin-2 in human biomaterials.
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11
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Wijegunawardana D, Vishal SS, Venkatesh N, Gopal PP. Ataxin-2 polyglutamine expansions aberrantly sequester TDP-43, drive ribonucleoprotein condensate transport dysfunction and suppress local translation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.30.526372. [PMID: 36778347 PMCID: PMC9915502 DOI: 10.1101/2023.01.30.526372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Altered RNA metabolism is a common pathogenic mechanism linked to familial and sporadic Amyotrophic lateral sclerosis (ALS). ALS is characterized by mislocalization and aggregation of TDP-43, an RNA-binding protein (RBP) with multiple roles in post-transcriptional RNA processing. Recent studies have identified genetic interactions between TDP-43 and Ataxin-2, a polyglutamine (polyQ) RBP in which intermediate length polyQ expansions confer increased ALS risk. Here, we used live-cell confocal imaging, photobleaching and translation reporter assays to study the localization, transport dynamics and mRNA regulatory functions of TDP-43/Ataxin-2 in rodent primary cortical neurons. We show that Ataxin-2 polyQ expansions aberrantly sequester TDP-43 within ribonucleoprotein (RNP) condensates, and disrupt both its motility along the axon and liquid-like properties. Our data suggest that Ataxin-2 governs motility and translation of neuronal RNP condensates and that Ataxin-2 polyQ expansions fundamentally perturb spatial localization of mRNA and suppress local translation. Overall, these results indicate Ataxin-2 polyQ expansions have detrimental effects on stability, localization, and translation of transcripts critical for axonal and cytoskeletal integrity, particularly important for motor neurons.
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12
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Rodriguez CM, Bechek SC, Jones GL, Nakayama L, Akiyama T, Kim G, Solow-Cordero DE, Strittmatter SM, Gitler AD. Targeting RTN4/NoGo-Receptor reduces levels of ALS protein ataxin-2. Cell Rep 2022; 41:111505. [PMID: 36288715 PMCID: PMC9664481 DOI: 10.1016/j.celrep.2022.111505] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 05/30/2022] [Accepted: 09/22/2022] [Indexed: 01/27/2023] Open
Abstract
Gene-based therapeutic strategies to lower ataxin-2 levels are emerging for the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and spinocerebellar ataxia type 2 (SCA2). Additional strategies to lower levels of ataxin-2 could be beneficial. Here, we perform a genome-wide arrayed small interfering RNA (siRNA) screen in human cells and identify RTN4R, the gene encoding the RTN4/NoGo-Receptor, as a potent modifier of ataxin-2 levels. RTN4R knockdown, or treatment with a peptide inhibitor, is sufficient to lower ataxin-2 protein levels in mouse and human neurons in vitro, and Rtn4r knockout mice have reduced ataxin-2 levels in vivo. We provide evidence that ataxin-2 shares a role with the RTN4/NoGo-Receptor in limiting axonal regeneration. Reduction of either protein increases axonal regrowth following axotomy. These data define the RTN4/NoGo-Receptor as a novel therapeutic target for ALS and SCA2 and implicate the targeting of ataxin-2 as a potential treatment following nerve injury.
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Affiliation(s)
- Caitlin M Rodriguez
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Sophia C Bechek
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Graham L Jones
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Lisa Nakayama
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Tetsuya Akiyama
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Garam Kim
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Stanford Neurosciences Interdepartmental Program, Stanford University School of Medicine, Stanford, CA, USA
| | - David E Solow-Cordero
- High-Throughput Bioscience Center, Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
| | - Stephen M Strittmatter
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT, USA
| | - Aaron D Gitler
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA.
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13
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Ganassi M, Zammit PS. Involvement of muscle satellite cell dysfunction in neuromuscular disorders: Expanding the portfolio of satellite cell-opathies. Eur J Transl Myol 2022; 32:10064. [PMID: 35302338 PMCID: PMC8992676 DOI: 10.4081/ejtm.2022.10064] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 02/11/2022] [Indexed: 12/03/2022] Open
Abstract
Neuromuscular disorders are a heterogeneous group of acquired or hereditary conditions that affect striated muscle function. The resulting decrease in muscle strength and motility irreversibly impacts quality of life. In addition to directly affecting skeletal muscle, pathogenesis can also arise from dysfunctional crosstalk between nerves and muscles, and may include cardiac impairment. Muscular weakness is often progressive and paralleled by continuous decline in the ability of skeletal muscle to functionally adapt and regenerate. Normally, the skeletal muscle resident stem cells, named satellite cells, ensure tissue homeostasis by providing myoblasts for growth, maintenance, repair and regeneration. We recently defined 'Satellite Cell-opathies' as those inherited neuromuscular conditions presenting satellite cell dysfunction in muscular dystrophies and myopathies (doi:10.1016/j.yexcr.2021.112906). Here, we expand the portfolio of Satellite Cell-opathies by evaluating the potential impairment of satellite cell function across all 16 categories of neuromuscular disorders, including those with mainly neurogenic and cardiac involvement. We explore the expression dynamics of myopathogenes, genes whose mutation leads to skeletal muscle pathogenesis, using transcriptomic analysis. This revealed that 45% of myopathogenes are differentially expressed during early satellite cell activation (0 - 5 hours). Of these 271 myopathogenes, 83 respond to Pax7, a master regulator of satellite cells. Our analysis suggests possible perturbation of satellite cell function in many neuromuscular disorders across all categories, including those where skeletal muscle pathology is not predominant. This characterisation further aids understanding of pathomechanisms and informs on development of prognostic and diagnostic tools, and ultimately, new therapeutics.
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Affiliation(s)
- Massimo Ganassi
- King's College London, Randall Centre for Cell and Molecular Biophysics, Guy's Campus, London.
| | - Peter S Zammit
- King's College London, Randall Centre for Cell and Molecular Biophysics, Guy's Campus, London.
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14
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Sundberg CA, Lakk M, Paul S, Figueroa KP, Scoles DR, Pulst SM, Križaj D. The RNA-binding protein and stress granule component ATAXIN-2 is expressed in mouse and human tissues associated with glaucoma pathogenesis. J Comp Neurol 2022; 530:537-552. [PMID: 34350994 PMCID: PMC8716417 DOI: 10.1002/cne.25228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 07/06/2021] [Indexed: 02/03/2023]
Abstract
Polyglutamine repeat expansions in the Ataxin-2 (ATXN2) gene were first implicated in Spinocerebellar Ataxia Type 2, a disease associated with degeneration of motor neurons and Purkinje cells. Recent studies linked single nucleotide polymorphisms in the gene to elevated intraocular pressure in primary open angle glaucoma (POAG); yet, the localization of ATXN2 across glaucoma-relevant tissues of the vertebrate eye has not been thoroughly examined. This study characterizes ATXN2 expression in the mouse and human retina, and anterior eye, using an antibody validated in ATXN2-/- retinas. ATXN2-ir was localized to cytosolic sub compartments in retinal ganglion cell (RGC) somata and proximal dendrites in addition to GABAergic, glycinergic, and cholinergic amacrine cells in the inner plexiform layer (IPL) and displaced amacrine cells. Human, but not mouse retinas showed modest immunolabeling of bipolar cells. ATXN2 immunofluorescence was prominent in the trabecular meshwork and pigmented and nonpigmented cells of the ciliary body, with analyses of primary human trabecular meshwork cells confirming the finding. The expression of ATXN2 in key POAG-relevant ocular tissues supports the potential role in autophagy and stress granule formation in response to ocular hypertension.
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Affiliation(s)
- Chad A. Sundberg
- Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Monika Lakk
- Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Sharan Paul
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Karla P. Figueroa
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Daniel R. Scoles
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Stefan M. Pulst
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA
- Department of Neurobiology & Anatomy, University of Utah, Salt Lake City, Utah, USA
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15
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Sujkowski A, Hong L, Wessells RJ, Todi SV. The protective role of exercise against age-related neurodegeneration. Ageing Res Rev 2022; 74:101543. [PMID: 34923167 PMCID: PMC8761166 DOI: 10.1016/j.arr.2021.101543] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/01/2021] [Accepted: 12/14/2021] [Indexed: 02/08/2023]
Abstract
Endurance exercise is a widely accessible, low-cost intervention with a variety of benefits to multiple organ systems. Exercise improves multiple indices of physical performance and stimulates pronounced health benefits reducing a range of pathologies including metabolic, cardiovascular, and neurodegenerative disorders. Endurance exercise delays brain aging, preserves memory and cognition, and improves symptoms of neurodegenerative pathologies like Amyotrophic Lateral Sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, and various ataxias. Potential mechanisms underlying the beneficial effects of exercise include neuronal survival and plasticity, neurogenesis, epigenetic modifications, angiogenesis, autophagy, and the synthesis and release of neurotrophins and cytokines. In this review, we discuss shared benefits and molecular pathways driving the protective effects of endurance exercise on various neurodegenerative diseases in animal models and in humans.
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Affiliation(s)
- Alyson Sujkowski
- Department of Physiology, Wayne State University School of Medicine, USA; Department of Pharmacology, Wayne State University School of Medicine, USA
| | - Luke Hong
- Department of Pharmacology, Wayne State University School of Medicine, USA; Department of Neurology, Wayne State University School of Medicine, USA
| | - R J Wessells
- Department of Physiology, Wayne State University School of Medicine, USA
| | - Sokol V Todi
- Department of Pharmacology, Wayne State University School of Medicine, USA; Department of Neurology, Wayne State University School of Medicine, USA.
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16
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Mechanisms contributing to adverse outcomes of COVID-19 in obesity. Mol Cell Biochem 2022; 477:1155-1193. [PMID: 35084674 PMCID: PMC8793096 DOI: 10.1007/s11010-022-04356-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 01/07/2022] [Indexed: 01/08/2023]
Abstract
A growing amount of epidemiological data from multiple countries indicate an increased prevalence of obesity, more importantly central obesity, among hospitalized subjects with COVID-19. This suggests that obesity is a major factor contributing to adverse outcome of the disease. As it is a metabolic disorder with dysregulated immune and endocrine function, it is logical that dysfunctional metabolism contributes to the mechanisms behind obesity being a risk factor for adverse outcome in COVID-19. Emerging data suggest that in obese subjects, (a) the molecular mechanisms of viral entry and spread mediated through ACE2 receptor, a multifunctional host cell protein which links to cellular homeostasis mechanisms, are affected. This includes perturbation of the physiological renin-angiotensin system pathway causing pro-inflammatory and pro-thrombotic challenges (b) existent metabolic overload and ER stress-induced UPR pathway make obese subjects vulnerable to severe COVID-19, (c) host cell response is altered involving reprogramming of metabolism and epigenetic mechanisms involving microRNAs in line with changes in obesity, and (d) adiposopathy with altered endocrine, adipokine, and cytokine profile contributes to altered immune cell metabolism, systemic inflammation, and vascular endothelial dysfunction, exacerbating COVID-19 pathology. In this review, we have examined the available literature on the underlying mechanisms contributing to obesity being a risk for adverse outcome in COVID-19.
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17
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Rehbein U, Prentzell MT, Cadena Sandoval M, Heberle AM, Henske EP, Opitz CA, Thedieck K. The TSC Complex-mTORC1 Axis: From Lysosomes to Stress Granules and Back. Front Cell Dev Biol 2021; 9:751892. [PMID: 34778262 PMCID: PMC8586448 DOI: 10.3389/fcell.2021.751892] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/05/2021] [Indexed: 12/14/2022] Open
Abstract
The tuberous sclerosis protein complex (TSC complex) is a key integrator of metabolic signals and cellular stress. In response to nutrient shortage and stresses, the TSC complex inhibits the mechanistic target of rapamycin complex 1 (mTORC1) at the lysosomes. mTORC1 is also inhibited by stress granules (SGs), RNA-protein assemblies that dissociate mTORC1. The mechanisms of lysosome and SG recruitment of mTORC1 are well studied. In contrast, molecular details on lysosomal recruitment of the TSC complex have emerged only recently. The TSC complex subunit 1 (TSC1) binds lysosomes via phosphatidylinositol-3,5-bisphosphate [PI(3,5)P2]. The SG assembly factors 1 and 2 (G3BP1/2) have an unexpected lysosomal function in recruiting TSC2 when SGs are absent. In addition, high density lipoprotein binding protein (HDLBP, also named Vigilin) recruits TSC2 to SGs under stress. In this mini-review, we integrate the molecular mechanisms of lysosome and SG recruitment of the TSC complex. We discuss their interplay in the context of cell proliferation and migration in cancer and in the clinical manifestations of tuberous sclerosis complex disease (TSC) and lymphangioleiomyomatosis (LAM).
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Affiliation(s)
- Ulrike Rehbein
- Laboratory for Metabolic Signaling, Institute of Biochemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Mirja Tamara Prentzell
- Brain Cancer Metabolism Group, German Consortium of Translational Cancer Research (DKTK) & German Cancer Research Center (DKFZ), Heidelberg, Germany.,Faculty of Bioscience, Heidelberg University, Heidelberg, Germany
| | - Marti Cadena Sandoval
- Laboratory for Metabolic Signaling, Institute of Biochemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria.,Section Systems Medicine of Metabolism and Signaling, Department of Pediatrics, University of Groningen and University Medical Center Groningen, Groningen, Netherlands
| | - Alexander Martin Heberle
- Laboratory for Metabolic Signaling, Institute of Biochemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria.,Section Systems Medicine of Metabolism and Signaling, Department of Pediatrics, University of Groningen and University Medical Center Groningen, Groningen, Netherlands
| | - Elizabeth P Henske
- Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Christiane A Opitz
- Brain Cancer Metabolism Group, German Consortium of Translational Cancer Research (DKTK) & German Cancer Research Center (DKFZ), Heidelberg, Germany.,Department of Neurology, National Center for Tumor Diseases, University Hospital Heidelberg, Heidelberg, Germany
| | - Kathrin Thedieck
- Laboratory for Metabolic Signaling, Institute of Biochemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria.,Section Systems Medicine of Metabolism and Signaling, Department of Pediatrics, University of Groningen and University Medical Center Groningen, Groningen, Netherlands.,Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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18
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Charar C, Metsuyanim-Cohen S, Bar DZ. Lamin regulates the dietary restriction response via the mTOR pathway in Caenorhabditis elegans. J Cell Sci 2021; 134:272061. [PMID: 34383046 PMCID: PMC8445603 DOI: 10.1242/jcs.258428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 07/30/2021] [Indexed: 11/30/2022] Open
Abstract
Animals subjected to dietary restriction (DR) have reduced body size, low fecundity, slower development, lower fat content and longer life span. We identified lamin as a regulator of multiple dietary restriction phenotypes. Downregulation of lmn-1, the single Caenorhabditis elegans lamin gene, increased animal size and fat content specifically in DR animals. The LMN-1 protein acts in the mTOR pathway, upstream of RAPTOR and S6 kinase β1 (S6K), a key component of and target of the mechanistic target of rapamycin (mTOR) complex 1 (mTORC1), respectively. DR excludes the mTORC1 activator RAGC-1 from the nucleus. Downregulation of lmn-1 restores RAGC-1 to the nucleus, a necessary step for the activation of the mTOR pathway. These findings further link lamin to metabolic regulation. Summary: Downregulation of the single C. elegans lamin gene increases animal size and fat content specifically in dietary restricted animals. The lamin protein acts in the mTOR pathway to regulate these phenotypes.
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Affiliation(s)
- Chayki Charar
- The School of Dental Medicine, The Faculty of Medicine, Tel Aviv University, Israel.,The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Israel
| | | | - Daniel Z Bar
- The School of Dental Medicine, The Faculty of Medicine, Tel Aviv University, Israel
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19
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Scoles DR, Dansithong W, Pflieger LT, Paul S, Gandelman M, Figueroa KP, Rigo F, Bennett CF, Pulst SM. ALS-associated genes in SCA2 mouse spinal cord transcriptomes. Hum Mol Genet 2021; 29:1658-1672. [PMID: 32307524 PMCID: PMC7322574 DOI: 10.1093/hmg/ddaa072] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 04/07/2020] [Accepted: 04/09/2020] [Indexed: 12/12/2022] Open
Abstract
The spinocerebellar ataxia type 2 (SCA2) gene ATXN2 has a prominent role in the pathogenesis and treatment of amyotrophic lateral sclerosis (ALS). In addition to cerebellar ataxia, motor neuron disease is often seen in SCA2, and ATXN2 CAG repeat expansions in the long normal range increase ALS risk. Also, lowering ATXN2 expression in TDP-43 ALS mice prolongs their survival. Here we investigated the ATXN2 relationship with motor neuron dysfunction in vivo by comparing spinal cord (SC) transcriptomes reported from TDP-43 and SOD1 ALS mice and ALS patients with those from SCA2 mice. SC transcriptomes were determined using an SCA2 bacterial artificial chromosome mouse model expressing polyglutamine expanded ATXN2. SCA2 cerebellar transcriptomes were also determined, and we also investigated the modification of gene expression following treatment of SCA2 mice with an antisense oligonucleotide (ASO) lowering ATXN2 expression. Differentially expressed genes (DEGs) defined three interconnected pathways (innate immunity, fatty acid biosynthesis and cholesterol biosynthesis) in separate modules identified by weighted gene co-expression network analysis. Other key pathways included the complement system and lysosome/phagosome pathways. Of all DEGs in SC, 12.6% were also dysregulated in the cerebellum. Treatment of mice with an ATXN2 ASO also modified innate immunity, the complement system and lysosome/phagosome pathways. This study provides new insights into the underlying molecular basis of SCA2 SC phenotypes and demonstrates annotated pathways shared with TDP-43 and SOD1 ALS mice and ALS patients. It also emphasizes the importance of ATXN2 in motor neuron degeneration and confirms ATXN2 as a therapeutic target.
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Affiliation(s)
- Daniel R Scoles
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, UT 84132, USA
| | - Warunee Dansithong
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, UT 84132, USA
| | - Lance T Pflieger
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, UT 84132, USA.,Department of Biomedical Informatics, University of Utah, 421 Wakara Way, Salt Lake City, UT 84108, USA
| | - Sharan Paul
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, UT 84132, USA
| | - Mandi Gandelman
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, UT 84132, USA
| | - Karla P Figueroa
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, UT 84132, USA
| | - Frank Rigo
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - C Frank Bennett
- Ionis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, UT 84132, USA
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20
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The ATXN2 Orthologs CID3 and CID4, Act Redundantly to In-Fluence Developmental Pathways throughout the Life Cycle of Arabidopsis thaliana. Int J Mol Sci 2021; 22:ijms22063068. [PMID: 33802796 PMCID: PMC8002431 DOI: 10.3390/ijms22063068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/15/2021] [Accepted: 02/15/2021] [Indexed: 11/17/2022] Open
Abstract
RNA-binding proteins (RBPs) are key elements involved in post-transcriptional regulation. Ataxin-2 (ATXN2) is an evolutionarily conserved RBP protein, whose function has been studied in several model organisms, from Saccharomyces cerevisiae to the Homo sapiens. ATXN2 interacts with poly(A) binding proteins (PABP) and binds to specific sequences at the 3'UTR of target mRNAs to stabilize them. CTC-Interacting Domain3 (CID3) and CID4 are two ATXN2 orthologs present in plant genomes whose function is unknown. In the present study, phenotypical and transcriptome profiling were used to examine the role of CID3 and CID4 in Arabidopsis thaliana. We found that they act redundantly to influence pathways throughout the life cycle. cid3cid4 double mutant showed a delay in flowering time and a reduced rosette size. Transcriptome profiling revealed that key factors that promote floral transition and floral meristem identity were downregulated in cid3cid4 whereas the flowering repressor FLOWERING LOCUS C (FLC) was upregulated. Expression of key factors in the photoperiodic regulation of flowering and circadian clock pathways, were also altered in cid3cid4, as well as the expression of several transcription factors and miRNAs encoding genes involved in leaf growth dynamics. These findings reveal that ATXN2 orthologs may have a role in developmental pathways throughout the life cycle of plants.
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21
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Singh A, Hulsmeier J, Kandi AR, Pothapragada SS, Hillebrand J, Petrauskas A, Agrawal K, RT K, Thiagarajan D, Jayaprakashappa D, VijayRaghavan K, Ramaswami M, Bakthavachalu B. Antagonistic roles for Ataxin-2 structured and disordered domains in RNP condensation. eLife 2021; 10:e60326. [PMID: 33689682 PMCID: PMC7946432 DOI: 10.7554/elife.60326] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 02/23/2021] [Indexed: 02/07/2023] Open
Abstract
Ataxin-2 (Atx2) is a translational control molecule mutated in spinocerebellar ataxia type II and amyotrophic lateral sclerosis. While intrinsically disordered domains (IDRs) of Atx2 facilitate mRNP condensation into granules, how IDRs work with structured domains to enable positive and negative regulation of target mRNAs remains unclear. Using the Targets of RNA-Binding Proteins Identified by Editing technology, we identified an extensive data set of Atx2-target mRNAs in the Drosophila brain and S2 cells. Atx2 interactions with AU-rich elements in 3'UTRs appear to modulate stability/turnover of a large fraction of these target mRNAs. Further genomic and cell biological analyses of Atx2 domain deletions demonstrate that Atx2 (1) interacts closely with target mRNAs within mRNP granules, (2) contains distinct protein domains that drive or oppose RNP-granule assembly, and (3) has additional essential roles outside of mRNP granules. These findings increase the understanding of neuronal translational control mechanisms and inform strategies for Atx2-based interventions under development for neurodegenerative disease.
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Affiliation(s)
- Amanjot Singh
- National Centre for Biological SciencesBangaloreIndia
| | - Joern Hulsmeier
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College DublinDublinIreland
| | - Arvind Reddy Kandi
- National Centre for Biological SciencesBangaloreIndia
- Tata Institute for Genetics and Society Centre at inStem, Bellary RoadBangaloreIndia
| | | | - Jens Hillebrand
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College DublinDublinIreland
| | - Arnas Petrauskas
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College DublinDublinIreland
| | - Khushboo Agrawal
- Tata Institute for Genetics and Society Centre at inStem, Bellary RoadBangaloreIndia
- School of Biotechnology, Amrita Vishwa Vidyapeetham UniversityKollamIndia
| | - Krishnan RT
- National Centre for Biological SciencesBangaloreIndia
| | | | | | | | - Mani Ramaswami
- National Centre for Biological SciencesBangaloreIndia
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College DublinDublinIreland
| | - Baskar Bakthavachalu
- National Centre for Biological SciencesBangaloreIndia
- Tata Institute for Genetics and Society Centre at inStem, Bellary RoadBangaloreIndia
- School of Basic Sciences, Indian Institute of TechnologyMandiIndia
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22
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Rodriguez-Graña T, Rodríguez-Labrada R, Santana-Porbén S, Reynaldo-Cejas L, Medrano-Montero J, Canales-Ochoa N, Silva-Ricardo Y, Torres-Vega R, González-Zaldivar Y, Almaguer-Gotay D, Auburger G, Velázquez-Pérez L. Weight loss is correlated with disease severity in Spinocerebellar ataxia type 2: a cross-sectional cohort study. Nutr Neurosci 2021; 25:1747-1755. [PMID: 33687306 DOI: 10.1080/1028415x.2021.1895479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
BACKGROUND Body weight changes occur frequently during advanced stages of Spinocerebellar Ataxia type 2 (SCA2), nevertheless limited information exists on biomarkers of nutritional status of these patients. OBJECTIVE. To assess changes in surrogate nutritional markers of SCA2 patients; to explore their associations with expanded CAG repeats and disease severity. METHODS One-hundred-thirteen SCA2 patients and 50 healthy controls underwent a comprehensive anthropometrical and biochemical assessment protocol of the nutritional status. Neurological and genotype assessments were also performed. RESULTS A decrease in weight, body mass index (BMI), cutaneous skinfold thickness, fat mass, arm muscle circumference, calf circumference and skeletal muscle mass was observed in SCA2 patients compared to the controls. The total/HDL cholesterol ratio was significantly reduced in patients. BMI was correlated with the age at onset. Overall, anthropometric measures were correlated with clinical markers of disease severity and were more evident in severe and moderate cases. CONCLUSIONS Using anthropometric measures in the assessment of the nutritional status of SCA2 patients might provide hints about pathophysiological mechanisms that underlie metabolic abnormalities in SCA2. Anthropometric are close related with disease severity and progression, and trigger preventive therapies aimed to ameliorate weight loss and wasting in these patients.
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Affiliation(s)
- Tania Rodriguez-Graña
- Centre for the Research and Rehabilitation of Hereditary Ataxias, El Llano, Holguin, Cuba.,Medical University of Holguin, Holguin, Cuba
| | - Roberto Rodríguez-Labrada
- Centre for the Research and Rehabilitation of Hereditary Ataxias, El Llano, Holguin, Cuba.,Cuban Neuroscience Centre, La Havana, Cuba
| | | | - Lorenzo Reynaldo-Cejas
- Centre for the Research and Rehabilitation of Hereditary Ataxias, El Llano, Holguin, Cuba
| | | | - Nalia Canales-Ochoa
- Centre for the Research and Rehabilitation of Hereditary Ataxias, El Llano, Holguin, Cuba
| | | | - Reidenis Torres-Vega
- Centre for the Research and Rehabilitation of Hereditary Ataxias, El Llano, Holguin, Cuba
| | | | - Dennis Almaguer-Gotay
- Centre for the Research and Rehabilitation of Hereditary Ataxias, El Llano, Holguin, Cuba
| | - Georg Auburger
- Exp. Neurology, Medical Faculty, Goethe University, Frankfurt am Main, Germany
| | - Luis Velázquez-Pérez
- Centre for the Research and Rehabilitation of Hereditary Ataxias, El Llano, Holguin, Cuba.,Cuban Academy of Sciences, La Habana, Cuba
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23
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Dennis AG, Almaguer-Mederos LE, Raúl RA, Roberto RL, Luis VP, Dany CA, Yanetza GZ, Yaimeé VM, Annelié ED, Arnoy PA, Reydenis TV. Redox Imbalance Associates with Clinical Worsening in Spinocerebellar Ataxia Type 2. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:9875639. [PMID: 33688396 PMCID: PMC7920744 DOI: 10.1155/2021/9875639] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 12/24/2020] [Accepted: 02/05/2021] [Indexed: 12/30/2022]
Abstract
BACKGROUND Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disease presenting with redox imbalance. However, the nature and implications of redox imbalance in SCA2 physiopathology have not been fully understood. OBJECTIVE The objective of this study is to assess the redox imbalance and its association with disease severity in SCA2 mutation carriers. METHODS A case-control study was conducted involving molecularly confirmed SCA2 patients, presymptomatic individuals, and healthy controls. Several antioxidant parameters were assessed, including serum thiol concentration and the superoxide dismutase, catalase, and glutathione S-transferase enzymatic activities. Also, several prooxidant parameters were evaluated, including thiobarbituric acid-reactive species and protein carbonyl concentrations. Damage, protective, and OXY scores were computed. Clinical correlates were established. RESULTS Significant differences were found between comparison groups for redox markers, including protein carbonyl concentration (F = 3.30; p = 0.041), glutathione S-transferase activity (F = 4.88; p = 0.009), and damage (F = 3.20; p = 0.045), protection (F = 12.75; p < 0.001), and OXY (F = 7.29; p = 0.001) scores. Protein carbonyl concentration was positively correlated with CAG repeat length (r = 0.27; p = 0.022), while both protein carbonyl concentration (r = -0.27; p = 0.018) and OXY score (r = -0.25; p = 0.013) were inversely correlated to the disease duration. Increasing levels of antioxidants and decreasing levels of prooxidant parameters were associated with clinical worsening. CONCLUSIONS There is a disruption of redox balance in SCA2 mutation carriers which depends on the disease stage. Besides, redox changes associate with markers of disease severity, suggesting a link between disruption of redox balance and SCA2 physiopathology.
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Affiliation(s)
- Almaguer-Gotay Dennis
- Center for the Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
- University of Medical Sciences of Holguín, Cuba
| | - Luis E. Almaguer-Mederos
- Center for the Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
- University of Medical Sciences of Holguín, Cuba
| | - Rodríguez-Aguilera Raúl
- Center for the Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
- University of Medical Sciences of Holguín, Cuba
| | | | - Velázquez-Pérez Luis
- Center for the Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
- Cuban Academy of Sciences, Cuba
| | - Cuello-Almarales Dany
- Center for the Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
- University of Medical Sciences of Holguín, Cuba
| | - González-Zaldívar Yanetza
- Center for the Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
- University of Medical Sciences of Holguín, Cuba
| | - Vázquez-Mojena Yaimeé
- Center for the Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
| | | | - Peña-Acosta Arnoy
- Center for the Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
| | - Torres-Vega Reydenis
- Center for the Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
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24
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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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25
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Almaguer-Mederos LE, Pérez-Ávila I, Aguilera-Rodríguez R, Velázquez-Garcés M, Almaguer-Gotay D, Hechavarría-Pupo R, Rodríguez-Estupiñán A, Auburger G. Body Mass Index Is Significantly Associated With Disease Severity in Spinocerebellar Ataxia Type 2 Patients. Mov Disord 2021; 36:1372-1380. [PMID: 33548146 DOI: 10.1002/mds.28498] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 12/09/2020] [Accepted: 12/21/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Spinocerebellar ataxia type 2 is a progressive neurodegenerative disorder due to an unstable expansion of a CAG repeat in the ATXN2 gene. Although weight loss has been associated with disease progression in several neurodegenerative conditions, it has been barely assessed in patients with spinocerebellar ataxia type 2. OBJECTIVE The objective of this study was to test whether body mass index is altered in patients with spinocerebellar ataxia type 2 with varying expansion sizes from early to late disease stages. METHODS A cross-sectional case-control study was performed, which included 222 clinically and molecularly diagnosed patients and 214 sex- and age-matched healthy individuals. ATXN2 genotypes and sex were considered as risk factors. Clinical outcomes included the body mass index, age at onset, disease duration, Scale for the Assessment and Rating of Ataxia score, disease stage, dysphagia, and progression rate. Multiple linear regression models were generated. RESULTS Body mass index was significantly decreased in male patients, but not in female patients, relative to control subjects. In addition to sex, body mass index was significantly associated with age at onset and progression rate. Conversely, body mass index, along with repeat length in ATXN2 expanded alleles and disease duration, was associated with Scale for the Assessment and Rating of Ataxia score. In addition, body mass index, along with the age at onset and the repeat length in ATXN2 normal and expanded alleles, has a significant influence on progression rate. CONCLUSIONS Body mass index might be a useful biomarker of disease severity, particularly in male patients with spinocerebellar ataxia type 2 in the context of nutritional interventions or clinical trials assessing the efficacy of promising new drugs. © 2021 International Parkinson and Movement Disorder Society.
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Affiliation(s)
| | - Ilbedis Pérez-Ávila
- Center for the Investigation and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Center for Sports Medicine, Holguín, Cuba
| | | | | | - Dennis Almaguer-Gotay
- Center for the Investigation and Rehabilitation of Hereditary Ataxias, Holguín, Cuba
| | | | | | - Georg Auburger
- Experimental Neurology, Goethe University Medical Faculty, Frankfurt, Germany
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26
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Cha IJ, Lee D, Park SS, Chung CG, Kim SY, Jo MG, Kim SY, Lee BH, Lee YS, Lee SB. Ataxin-2 Dysregulation Triggers a Compensatory Fragile X Mental Retardation Protein Decrease in Drosophila C4da Neurons. Mol Cells 2020; 43:870-879. [PMID: 33115979 PMCID: PMC7604024 DOI: 10.14348/molcells.2020.0158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 09/24/2020] [Accepted: 09/24/2020] [Indexed: 12/19/2022] Open
Abstract
Dendrites require precise and timely delivery of protein substrates to distal areas to ensure the correct morphology and function of neurons. Many of these protein substrates are supplied in the form of ribonucleoprotein (RNP) complex consisting of RNA-binding proteins (RBPs) and mRNAs, which are subsequently translated in distal dendritic areas. It remains elusive, however, whether key RBPs supply mRNA according to local demands individually or in a coordinated manner. In this study, we investigated how Drosophila sensory neurons respond to the dysregulation of a disease-associated RBP, Ataxin-2 (ATX2), which leads to dendritic defects. We found that ATX2 plays a crucial role in spacing dendritic branches for the optimal dendritic receptive fields in Drosophila class IV dendritic arborization (C4da) neurons, where both expression level and subcellular location of ATX2 contribute significantly to this effect. We showed that translational upregulation through the expression of eukaryotic translation initiation factor 4E (eIF4E) further enhanced the ATX2-induced dendritic phenotypes. Additionally, we found that the expression level of another disease-associated RBP, fragile X mental retardation protein (FMRP), decreased in both cell bodies and dendrites when neurons were faced with aberrant upregulation of ATX2. Finally, we revealed that the PAM2 motif of ATX2, which mediates its interaction with poly(A)-binding protein (PABP), is potentially necessary for the decrease of FMRP in certain neuronal stress conditions. Collectively, our data suggest that dysregulation of RBPs triggers a compensatory regulation of other functionally-overlapping RBPs to minimize RBP dysregulation-associated aberrations that hinder neuronal homeostasis in dendrites.
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Affiliation(s)
- In Jun Cha
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Davin Lee
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Sung Soon Park
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Chang Geon Chung
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Seung Yeon Kim
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Min Gu Jo
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Seung Yeol Kim
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Byung-Hoon Lee
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
- Department of New Biology, DGIST, Daegu 42988, Korea
| | - Young-Sam Lee
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
- Department of New Biology, DGIST, Daegu 42988, Korea
- Well Aging Research Center, Division of Biotechnology, DGIST, Daegu 42988, Korea
| | - Sung Bae Lee
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
- Well Aging Research Center, Division of Biotechnology, DGIST, Daegu 42988, Korea
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27
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Watanabe R, Higashi S, Nonaka T, Kawakami I, Oshima K, Niizato K, Akiyama H, Yoshida M, Hasegawa M, Arai T. Intracellular dynamics of Ataxin-2 in the human brains with normal and frontotemporal lobar degeneration with TDP-43 inclusions. Acta Neuropathol Commun 2020; 8:176. [PMID: 33115537 PMCID: PMC7594343 DOI: 10.1186/s40478-020-01055-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 10/10/2020] [Indexed: 12/15/2022] Open
Abstract
TAR DNA-binding protein of 43 kDa (TDP-43) is a major component of intracellular aggregates formed in brains of the patients with frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS), which are correctively referred to as TDP-43 proteinopathies. A link between Ataxin-2 (ATXN2) and TDP-43 proteinopathies was established when intermediate CAG repeat expansions of ATXN2 gene were found to be associated with ALS and it was shown that ATXN2 modifies TDP-43 toxicity. Although ATXN2's contribution to TDP-43 proteinopathies has been mostly studied in ALS, recent studies have shown that intermediate repeat expansions of ATXN2 also influence the phenotype of FTLD by an unknown mechanism. To address this issue, we immunohistochemically and biochemically analyzed the intracellular dynamics of ATXN2 in brains of normal controls and FTLD-TDP cases. The immunohistochemical studies revealed that ATXN2 localized in the neuronal cytoplasm and proximal dendrites, and expressed widely and uniformly in normal human brains. A semi-quantitative immunofluorescent analysis of normal brains revealed that the cytoplasmic ATXN2 strongly associates with ribosomal protein S6 and poly-A binding protein 1 and partially overlaps with the endoplasmic reticulum marker Calnexin, suggesting a major role of ATXN2 in protein synthesis. The results of immunohistochemical and biochemical analyses of brains from FTLD-TDP cases showed the colocalization of ATXN2 and phosphorylated TDP-43 in the dystrophic neurites and the neuronal cytoplasmic inclusions in the hippocampal region, and a significant reduction of ATXN2 protein compared to controls. These results suggest that ATXN2 is involved in the pathological process of FTLD-TDP. It remains to be clarified whether reduced ATXN2 expression induces neurodegeneration by impairing protein synthesis or plays a neuroprotective role by attenuating the toxicity of TDP-43 aggregates in FTLD-TDP and other TDP-43 proteinopathies.
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Affiliation(s)
- Ryohei Watanabe
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo Japan
- Department of Psychiatry, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki Japan
- Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, 2-1-1 Kamikitazawa, Setagaya, Tokyo Japan
| | - Shinji Higashi
- Department of Psychiatry, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki Japan
- Department of Psychiatry, Tokyo Medical University Ibaraki Medical Center, 3-20-1 Chuo, Ami, Inashiki, Ibaraki Japan
| | - Takashi Nonaka
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo Japan
| | - Ito Kawakami
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo Japan
- Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, 2-1-1 Kamikitazawa, Setagaya, Tokyo Japan
- Brain Bank for Aging Research, Department of Neuropathology, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi, Tokyo Japan
| | - Kenichi Oshima
- Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, 2-1-1 Kamikitazawa, Setagaya, Tokyo Japan
| | - Kazuhiro Niizato
- Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, 2-1-1 Kamikitazawa, Setagaya, Tokyo Japan
| | - Haruhiko Akiyama
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo Japan
- Department of Clinical Research, Yokohama Brain and Spine Center, 1-2-1 Takigashira, Isogo, Yokohama, Kanagawa Japan
| | - Mari Yoshida
- Institute for Medical Science of Aging, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Aichi Japan
| | - Masato Hasegawa
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo Japan
| | - Tetsuaki Arai
- Department of Psychiatry, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki Japan
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28
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Inagaki H, Hosoda N, Tsuiji H, Hoshino SI. Direct evidence that Ataxin-2 is a translational activator mediating cytoplasmic polyadenylation. J Biol Chem 2020; 295:15810-15825. [PMID: 32989052 DOI: 10.1074/jbc.ra120.013835] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 09/13/2020] [Indexed: 12/27/2022] Open
Abstract
The RNA-binding protein Ataxin-2 binds to and stabilizes a number of mRNA sequences, including that of the transactive response DNA-binding protein of 43 kDa (TDP-43). Ataxin-2 is additionally involved in several processes requiring translation, such as germline formation, long-term habituation, and circadian rhythm formation. However, it has yet to be unambiguously demonstrated that Ataxin-2 is actually involved in activating the translation of its target mRNAs. Here we provide direct evidence from a polysome profile analysis showing that Ataxin-2 enhances translation of target mRNAs. Our recently established method for transcriptional pulse-chase analysis under conditions of suppressing deadenylation revealed that Ataxin-2 promotes post-transcriptional polyadenylation of the target mRNAs. Furthermore, Ataxin-2 binds to a poly(A)-binding protein PABPC1 and a noncanonical poly(A) polymerase PAPD4 via its intrinsically disordered region (amino acids 906-1095) to recruit PAPD4 to the targets. Post-transcriptional polyadenylation by Ataxin-2 explains not only how it activates translation but also how it stabilizes target mRNAs, including TDP-43 mRNA. Ataxin-2 is known to be a potent modifier of TDP-43 proteinopathies and to play a causative role in the neurodegenerative disease spinocerebellar ataxia type 2, so these findings suggest that Ataxin-2-induced cytoplasmic polyadenylation and activation of translation might impact neurodegeneration (i.e. TDP-43 proteinopathies), and this process could be a therapeutic target for Ataxin-2-related neurodegenerative disorders.
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Affiliation(s)
- Hiroto Inagaki
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Nao Hosoda
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Hitomi Tsuiji
- Department of Biomedical Science, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Shin-Ichi Hoshino
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan.
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29
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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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Bolourian A, Mojtahedi Z. Obesity and COVID-19: The mTOR pathway as a possible culprit. Obes Rev 2020; 21:e13084. [PMID: 32578354 PMCID: PMC7362054 DOI: 10.1111/obr.13084] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/03/2020] [Accepted: 06/04/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Alireza Bolourian
- College of Pharmacy, Oregon State University, Corvallis, Oregon, USA
| | - Zahra Mojtahedi
- Department of Health Care Administration and Policy, School of Public Health, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
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Zhan Y, Wang H, Ning Y, Zheng H, Liu S, Yang Y, Zhou M, Fan S. Understanding the roles of stress granule during chemotherapy for patients with malignant tumors. Am J Cancer Res 2020; 10:2226-2241. [PMID: 32905441 PMCID: PMC7471355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 07/19/2020] [Indexed: 06/11/2023] Open
Abstract
The assembly of stress granules (SGs) is a conserved mechanism to regulate protein synthesis under cell stress, where the translation of global protein is silenced and selective protein synthesis for survival maintains. SG formation confers survival advantages and chemotherapeutic resistance to malignant cells. Targeting SG assembly may represent a potential treatment strategy to overcome the primary and acquired chemotherapeutic resistance and enhance curative effect. We conduct a comprehensive review of the published literatures focusing on the drugs that potentially induce SGs and the related mechanism, retrospect the relationship between SGs and drug resistance related proteins, illuminate the regulated pathways and potential targets for SG assembly, and discuss future directions of overcoming the resistance to chemotherapy.
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Affiliation(s)
- Yuting Zhan
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha 410011, Hunan, China
| | - Haihua Wang
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha 410011, Hunan, China
| | - Yue Ning
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha 410011, Hunan, China
| | - Hongmei Zheng
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha 410011, Hunan, China
| | - Sile Liu
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha 410011, Hunan, China
| | - Yang Yang
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha 410011, Hunan, China
| | - Ming Zhou
- Cancer Research Institute Xiangya School of Medicine, Central South UniversityChangsha 410078, Hunan, China
| | - Songqing Fan
- Department of Pathology, The Second Xiangya Hospital, Central South UniversityChangsha 410011, Hunan, China
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32
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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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La Rosa P, Petrillo S, Bertini ES, Piemonte F. Oxidative Stress in DNA Repeat Expansion Disorders: A Focus on NRF2 Signaling Involvement. Biomolecules 2020; 10:biom10050702. [PMID: 32369911 PMCID: PMC7277112 DOI: 10.3390/biom10050702] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/13/2022] Open
Abstract
DNA repeat expansion disorders are a group of neuromuscular and neurodegenerative diseases that arise from the inheritance of long tracts of nucleotide repetitions, located in the regulatory region, introns, or inside the coding sequence of a gene. Although loss of protein expression and/or the gain of function of its transcribed mRNA or translated product represent the major pathogenic effect of these pathologies, mitochondrial dysfunction and imbalance in redox homeostasis are reported as common features in these disorders, deeply affecting their severity and progression. In this review, we examine the role that the redox imbalance plays in the pathological mechanisms of DNA expansion disorders and the recent advances on antioxidant treatments, particularly focusing on the expression and the activity of the transcription factor NRF2, the main cellular regulator of the antioxidant response.
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Sun Y, Jiang X, Pan R, Zhou X, Qin D, Xiong R, Wang Y, Qiu W, Wu A, Wu J. Escins Isolated from Aesculus chinensis Bge. Promote the Autophagic Degradation of Mutant Huntingtin and Inhibit its Induced Apoptosis in HT22 cells. Front Pharmacol 2020; 11:116. [PMID: 32158393 PMCID: PMC7052340 DOI: 10.3389/fphar.2020.00116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 01/28/2020] [Indexed: 12/27/2022] Open
Abstract
The pathogenesis of Huntington’s disease (HD), an inherited progressive neurodegenerative disease, is highly associated with the cytotoxicity-inducing mutant huntingtin (mHtt) protein. Emerging evidence indicates that autophagy plays a pivotal role in degrading aggregated proteins such as mHtt to enhance neuronal viability. In this study, by employing preparative high-performance liquid chromatography (pre-HPLC), ultra-high performance liquid chromatography diode-array-detector quadrupole time-of-flight mass spectrometry (UHPLC-DAD-Q-TOF-MS) and nuclear magnetic resonance (NMR), three escins, escin IA (EA), escin IB (EB) and isoescin IA (IEA), were isolated and identified from the seed of Aesculus chinensis Bge. (ACB). After EGFP-HTT74-overexpressing HT22 cells were treated with EA, EB and IEA at safe concentrations, the clearance of mHtt and mHtt-induced apoptosis were investigated by Western blot, immunofluorescence microscopy and flow cytometry methods. In addition, the autophagy induced by these escins in HT22 cells was monitored by detecting GFP-LC3 puncta, P62 and LC3 protein expression. The results showed that EA, EB and IEA could significantly decrease mHtt levels and inhibit its induced apoptosis in HT22 cells. In addition, these three saponins induced autophagic flux by increasing the ratio of RFP-LC3 to GFP-LC3, and by decreasing P62 expression. Among the tested escins, EB displayed the best autophagy induction, which was regulated via both the mTOR and ERK signaling pathways. Furthermore, the degradation of mHtt and the commensurate decrease in its cytotoxic effects by EA, EB and IEA were demonstrated to be closely associated with autophagy induction, which depended on ATG7. In conclusion, we are the first to report that the escins, including EA, EB and IEA are novel autophagy inducers that degrade mHtt and inhibit mHtt-induced apoptosis in vitro and in vivo. As a result of these findings, the triterpenoid saponins in ACB might be considered to be promising candidates for the treatment of HD in the future.
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Affiliation(s)
- Yueshan Sun
- School of Pharmacy, Southwest Medical University, Luzhou, China
| | - Xueqin Jiang
- School of Pharmacy, Southwest Medical University, Luzhou, China
| | - Rong Pan
- School of Pharmacy, Southwest Medical University, Luzhou, China
| | - Xiaogang Zhou
- School of Pharmacy, Southwest Medical University, Luzhou, China
| | - Dalian Qin
- School of Pharmacy, Southwest Medical University, Luzhou, China.,The Key Laboratory of Medical Electrophysiology, Sichuan Key Medical Laboratory of New Drug Discovery and Druggability Evaluation, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, Southwest Medical University, Luzhou, China
| | - Rui Xiong
- School of Pharmacy, Southwest Medical University, Luzhou, China
| | - Yiling Wang
- School of Pharmacy, Southwest Medical University, Luzhou, China
| | - Wenqiao Qiu
- School of Pharmacy, Southwest Medical University, Luzhou, China
| | - Anguo Wu
- School of Pharmacy, Southwest Medical University, Luzhou, China.,The Key Laboratory of Medical Electrophysiology, Sichuan Key Medical Laboratory of New Drug Discovery and Druggability Evaluation, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, Southwest Medical University, Luzhou, China
| | - Jianming Wu
- School of Pharmacy, Southwest Medical University, Luzhou, China.,The Key Laboratory of Medical Electrophysiology, Sichuan Key Medical Laboratory of New Drug Discovery and Druggability Evaluation, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, Southwest Medical University, Luzhou, China.,Department of Pharmacy, Affiliated Hospital of Southwest Medical University, Luzhou, China
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One‑carbon metabolism factor MTHFR variant is associated with saccade latency in Spinocerebellar Ataxia type 2. J Neurol Sci 2020; 409:116586. [PMID: 31812845 DOI: 10.1016/j.jns.2019.116586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 11/20/2019] [Accepted: 11/21/2019] [Indexed: 11/23/2022]
Abstract
BACKGROUND Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disorder due to a CAG-repeat expansion. This work is intended to identify modifiers of the clinical phenotype in SCA2, following up on recent genome-wide association analyses that demonstrated the prominent role of DNA-damage repair and methylation for the severity and progression of polyglutamine diseases. In particular, we assessed the impact of MTHFR as rate-limiting enzyme in DNA methylation pathways, which modulates cerebellar neurotransmission and motor neuron atrophy. METHODS A sample of 166 Cuban SCA2 patients and of 130 healthy subjects from the same geographical and ethnic background was selected. The ATXN2 CAG repeat length was determined by PCR followed by polyacrylamide gel electrophoresis. Two amino acid substitutions known to decrease the enzyme activity of MTHFR, encoded by C677T and A1298C polymorphisms, were assessed by PCR/RFLP. RESULTS No significant differences were observed for C677T or A1298C alleles or genotype frequencies between cases and controls, confirming that disease risk in SCA2 does not depend on MTHFR activity. However, MTHFR A1298C genotypes showed a significant association with saccade latency. CONCLUSIONS \MTHFR A1298C polymorphism is associated with saccade latency in SCA2 patients, but not with disease risk, age at onset or maximal saccade velocity. These results provide evidence that folate-mediated one‑carbon metabolism might be important in the physiopathology of SCA2.
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Velázquez-Pérez L, Medrano-Montero J, Rodríguez-Labrada R, Canales-Ochoa N, Campins Alí J, Carrillo Rodes FJ, Rodríguez Graña T, Hernández Oliver MO, Aguilera Rodríguez R, Domínguez Barrios Y, Torres Vega R, Flores Angulo L, Cordero Navarro NY, Sigler Villanueva AA, Gámez Rodríguez O, Sagaró Zambrano I, Navas Napóles NY, García Zacarías J, Serrano Barrera OR, Ramírez Bautista MB, Estupiñán Rodríguez A, Guerra Rondón LA, Vázquez-Mojena Y, González-Zaldivar Y, Almaguer Mederos LE, Leyva-Mérida A. Hereditary Ataxias in Cuba: A Nationwide Epidemiological and Clinical Study in 1001 Patients. THE CEREBELLUM 2020; 19:252-264. [DOI: 10.1007/s12311-020-01107-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Enhancement of Autophagy and Solubilization of Ataxin-2 Alleviate Apoptosis in Spinocerebellar Ataxia Type 2 Patient Cells. THE CEREBELLUM 2020; 19:165-181. [DOI: 10.1007/s12311-019-01092-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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38
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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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Abstract
Recent advances suggest that the response of RNA metabolism to stress has an important role in the pathophysiology of neurodegenerative diseases, particularly amyotrophic lateral sclerosis, frontotemporal dementias and Alzheimer disease. RNA-binding proteins (RBPs) control the utilization of mRNA during stress, in part through the formation of membraneless organelles termed stress granules (SGs). These structures form through a process of liquid-liquid phase separation. Multiple biochemical pathways regulate SG biology. The major signalling pathways regulating SG formation include the mammalian target of rapamycin (mTOR)-eukaryotic translation initiation factor 4F (eIF4F) and eIF2α pathways, whereas the pathways regulating SG dispersion and removal are mediated by valosin-containing protein and the autolysosomal cascade. Post-translational modifications of RBPs also strongly contribute to the regulation of SGs. Evidence indicates that SGs are supposed to be transient structures, but the chronic stresses associated with ageing lead to chronic, persistent SGs that appear to act as a nidus for the aggregation of disease-related proteins. We suggest a model describing how intrinsic vulnerabilities within the cellular RNA metabolism might lead to the pathological aggregation of RBPs when SGs become persistent. This process might accelerate the pathophysiology of many neurodegenerative diseases and myopathies, and it suggests new targets for disease intervention.
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Affiliation(s)
- Benjamin Wolozin
- Department of Pharmacology, Boston University School of Medicine, Boston, MA, USA.
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA.
| | - Pavel Ivanov
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- The Broad Institute of Harvard and MIT, Cambridge, MA, USA
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Egorova PA, Bezprozvanny IB. Molecular Mechanisms and Therapeutics for Spinocerebellar Ataxia Type 2. Neurotherapeutics 2019; 16:1050-1073. [PMID: 31435879 PMCID: PMC6985344 DOI: 10.1007/s13311-019-00777-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The effective therapeutic treatment and the disease-modifying therapy for spinocerebellar ataxia type 2 (SCA2) (a progressive hereditary disease caused by an expansion of polyglutamine in the ataxin-2 protein) is not available yet. At present, only symptomatic treatment and methods of palliative care are prescribed to the patients. Many attempts were made to study the physiological, molecular, and biochemical changes in SCA2 patients and in a variety of the model systems to find new therapeutic targets for SCA2 treatment. A better understanding of the uncovered molecular mechanisms of the disease allowed the scientific community to develop strategies of potential therapy and helped to create some promising therapeutic approaches for SCA2 treatment. Recent progress in this field will be discussed in this review article.
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Affiliation(s)
- Polina A Egorova
- Laboratory of Molecular Neurodegeneration, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, 195251, Russia
| | - Ilya B Bezprozvanny
- Laboratory of Molecular Neurodegeneration, Peter the Great St.Petersburg Polytechnic University, St. Petersburg, 195251, Russia.
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, ND12.200, Dallas, Texas, 75390, USA.
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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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Rodriguez CM, Todd PK. New pathologic mechanisms in nucleotide repeat expansion disorders. Neurobiol Dis 2019; 130:104515. [PMID: 31229686 DOI: 10.1016/j.nbd.2019.104515] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/07/2019] [Accepted: 06/19/2019] [Indexed: 12/14/2022] Open
Abstract
Tandem microsatellite repeats are common throughout the human genome and intrinsically unstable, exhibiting expansions and contractions both somatically and across generations. Instability in a small subset of these repeats are currently linked to human disease, although recent findings suggest more disease-causing repeats await discovery. These nucleotide repeat expansion disorders (NREDs) primarily affect the nervous system and commonly lead to neurodegeneration through toxic protein gain-of-function, protein loss-of-function, and toxic RNA gain-of-function mechanisms. However, the lines between these categories have blurred with recent findings of unconventional Repeat Associated Non-AUG (RAN) translation from putatively non-coding regions of the genome. Here we review two emerging topics in NREDs: 1) The mechanisms by which RAN translation occurs and its role in disease pathogenesis and 2) How nucleotide repeats as RNA and translated proteins influence liquid-liquid phase separation, membraneless organelle dynamics, and nucleocytoplasmic transport. We examine these topics with a particular eye on two repeats: the CGG repeat expansion responsible for Fragile X syndrome and Fragile X-associated Tremor Ataxia Syndrome (FXTAS) and the intronic GGGGCC repeat expansion in C9orf72, the most common inherited cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Our thesis is that these emerging disease mechanisms can inform a broader understanding of the native roles of microsatellites in cellular function and that aberrations in these native processes provide clues to novel therapeutic strategies for these currently untreatable disorders.
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Affiliation(s)
- C M Rodriguez
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA; Department of Genetics, Stanford University, Stanford, CA, USA
| | - P K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA; VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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Key J, Mueller AK, Gispert S, Matschke L, Wittig I, Corti O, Münch C, Decher N, Auburger G. Ubiquitylome profiling of Parkin-null brain reveals dysregulation of calcium homeostasis factors ATP1A2, Hippocalcin and GNA11, reflected by altered firing of noradrenergic neurons. Neurobiol Dis 2019; 127:114-130. [PMID: 30763678 DOI: 10.1016/j.nbd.2019.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/05/2018] [Accepted: 02/08/2019] [Indexed: 02/06/2023] Open
Abstract
Parkinson's disease (PD) is the second most frequent neurodegenerative disorder in the old population. Among its monogenic variants, a frequent cause is a mutation in the Parkin gene (Prkn). Deficient function of Parkin triggers ubiquitous mitochondrial dysfunction and inflammation in the brain, but it remains unclear how selective neural circuits become vulnerable and finally undergo atrophy. We attempted to go beyond previous work, mostly done in peripheral tumor cells, which identified protein targets of Parkin activity, an ubiquitin E3 ligase. Thus, we now used aged Parkin-knockout (KO) mouse brain for a global quantification of ubiquitylated peptides by mass spectrometry (MS). This approach confirmed the most abundant substrate to be VDAC3, a mitochondrial outer membrane porin that modulates calcium flux, while uncovering also >3-fold dysregulations for neuron-specific factors. Ubiquitylation decreases were prominent for Hippocalcin (HPCA), Calmodulin (CALM1/CALML3), Pyruvate Kinase (PKM2), sodium/potassium-transporting ATPases (ATP1A1/2/3/4), the Rab27A-GTPase activating protein alpha (TBC1D10A) and an ubiquitin ligase adapter (DDB1), while strong increases occurred for calcium transporter ATP2C1 and G-protein subunits G(i)/G(o)/G(Tr). Quantitative immunoblots validated elevated abundance for the electrogenic pump ATP1A2, for HPCA as neuron-specific calcium sensor, which stimulates guanylate cyclases and modifies axonal slow afterhyperpolarization (sAHP), and for the calcium-sensing G-protein GNA11. We assessed if compensatory molecular regulations become insufficient over time, leading to functional deficits. Patch clamp experiments in acute Parkin-KO brain slices indeed revealed alterations of the electrophysiological properties in aged noradrenergic locus coeruleus (LC) neurons. LC neurons of aged Parkin-KO brain showed an acceleration of the spontaneous pacemaker frequency, a reduction in sAHP and shortening of action potential duration, without modulation of KCNQ potassium currents. These findings indicate altered calcium-dependent excitability in a PARK2 model of PD, mediated by diminished turnover of potential Parkin targets such as ATP1A2 and HPCA. The data also identified further novel Parkin substrate candidates like SIRT2, OTUD7B and CUL5. Our elucidation of neuron-specific mechanisms of PD pathogenesis helps to explain the known exceptional susceptibility of noradrenergic and dopaminergic projections to alterations of calcium homeostasis and its mitochondrial buffering.
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Affiliation(s)
- J Key
- Exp. Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - A K Mueller
- Institute for Physiology and Pathophysiology, Vegetative Physiology and Marburg Center for Mind, Brain and Behavior - MCMBB; Clinic for Neurology, Philipps-University Marburg, 35037 Marburg, Germany
| | - S Gispert
- Exp. Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - L Matschke
- Institute for Physiology and Pathophysiology, Vegetative Physiology and Marburg Center for Mind, Brain and Behavior - MCMBB; Clinic for Neurology, Philipps-University Marburg, 35037 Marburg, Germany
| | - I Wittig
- Functional Proteomics, SFB 815 Core Unit, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - O Corti
- Institut du Cerveau et de la Moelle épinière, ICM, Paris, F-75013, France; Inserm, U1127, Paris, F-75013, France; CNRS, UMR 7225, Paris, F-75013, France; Sorbonne Universités, Paris, F-75013, France
| | - C Münch
- Institute of Biochemistry II, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - N Decher
- Institute for Physiology and Pathophysiology, Vegetative Physiology and Marburg Center for Mind, Brain and Behavior - MCMBB; Clinic for Neurology, Philipps-University Marburg, 35037 Marburg, Germany.
| | - G Auburger
- Exp. Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany.
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Abstract
The mechanistic target of rapamycin (mTOR) is an evolutionary conserved protein with a serine/threonine kinase activity that regulates cell growth, proliferation, motility, survival, protein synthesis, autophagy and transcription. It is embedded in 2 large protein complexes: mTORC1 and mTORC2. Regulation of specific mTOR pathway functions depends on multiple GTPases, that act either as regulators of mTOR protein complexes, coupling energy availability with mTORC1 activity, or as downstream effectors of both mTORC1 and mTORC2. In this commentary, we highlight the advantages of studying the mTOR pathway in C. elegans, including the subcellular localization of the signaling pathway components and the animal phenotypes following tissue specific protein over-expression or knockdown. One important regulator that is not limited to the mTOR pathway is RHEB. We discuss in vitro and in vivo data suggesting that RHEB can function as an inhibitor of mTOR when not bound to GTP. RHEB-1 itself is regulated by Rab GDP dissociation inhibitor β, which directly binds to ATX-2. We also highlight the roles of these proteins in dietary restriction-depended reduction in animal size and fat content.
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Affiliation(s)
- Daniel Z Bar
- a National Human Genome Research Institute, National Institutes of Health , Bethesda , MD , USA
| | - Chayki Charar
- b Department of Genetics , Institute of Life Sciences, Hebrew University of Jerusalem , Jerusalem , Israel
| | - Yosef Gruenbaum
- b Department of Genetics , Institute of Life Sciences, Hebrew University of Jerusalem , Jerusalem , Israel
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45
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Rodríguez-Díaz JC, Velázquez-Pérez L, Rodríguez Labrada R, Aguilera Rodríguez R, Laffita Pérez D, Canales Ochoa N, Medrano Montero J, Estupiñán Rodríguez A, Osorio Borjas M, Góngora Marrero M, Reynaldo Cejas L, González Zaldivar Y, Almaguer Gotay D. Neurorehabilitation therapy in spinocerebellar ataxia type 2: A 24-week, rater-blinded, randomized, controlled trial. Mov Disord 2018; 33:1481-1487. [PMID: 30132999 DOI: 10.1002/mds.27437] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 03/28/2018] [Accepted: 04/17/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Neurorehabilitation has become in a widely used approach in spinocerebellar ataxias, but there are scarce powerful clinical studies supporting this notion. OBJECTIVE The objective of this study was to assess the efficacy of a 24-week neurorehabilitative treatment in spinocerebellar ataxia type 2 patients. METHODS A total of 38 spinocerebellar ataxia type 2 patients were enrolled in a rater-blinded, 1:1 randomized, controlled trial using neurorehabilitation for 24 weeks. The treated group received 6 hours of neurorehabilitation therapy, emphasizing on balance, coordination, and muscle strengthening on weekdays, whereas the control group did not receive this intervention. Primary outcome measure was the Scale for the Assessment and Rating of Ataxia score, whereas secondary outcome measures included the count of Inventory of Non-Ataxia Symptoms and saccadic eye movement variables. RESULTS The rehabilitated group had high levels of adherence and retention to the therapy and showed a significant decrease of Scale for the Assessment and Rating of Ataxia score at 24 weeks when compared with the controls, mainly for the gait, stance, sitting, finger chase, and heel-shin test items. Changes in Scale for the Assessment and Rating of Ataxia scores were inversely correlated with the mutation size in the rehabilitated group. The nonataxia symptom count and saccadic measures were unchanged during the study. CONCLUSIONS A comprehensive 24-week rehabilitation program significantly improves the motor cerebellar symptoms of spinocerebellar ataxia type 2 patients as assessed by the ataxia rating score likely as result of the partial preservation of motor learning and neural plasticity mechanisms. These findings provide evidence in support of this therapeutic approach as palliative treatment in spinocerebellar ataxia type 2 suggesting its use in combination with other symptomatic or neuroprotective drugs and in prodromal stages. © 2018 International Parkinson and Movement Disorder Society.
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Affiliation(s)
| | - Luis Velázquez-Pérez
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Cuban Academy of Sciences, Havana, Cuba.,School of Physical Culture and Sport, University of Holguín, Holguín, Cuba
| | - Roberto Rodríguez Labrada
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Cuban Academy of Sciences, Havana, Cuba.,School of Physical Culture and Sport, University of Holguín, Holguín, Cuba
| | | | | | - Nalia Canales Ochoa
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba
| | - Jacqueline Medrano Montero
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,School of Physical Culture and Sport, University of Holguín, Holguín, Cuba
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46
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FAM98A is localized to stress granules and associates with multiple stress granule-localized proteins. Mol Cell Biochem 2018; 451:107-115. [DOI: 10.1007/s11010-018-3397-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 06/26/2018] [Indexed: 12/11/2022]
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47
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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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Zhou Y, Dong F, Mao Y. Control of CNS functions by RNA-binding proteins in neurological diseases. ACTA ACUST UNITED AC 2018; 4:301-313. [PMID: 30410853 DOI: 10.1007/s40495-018-0140-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Purpose of Review This review summarizes recent studies on the molecular mechanisms of RNA binding proteins (RBPs) that control neurological functions and pathogenesis in various neurodevelopmental and neurodegenerative diseases, including autism spectrum disorders, schizophrenia, Alzheimer's disease, amyotrophic lateral sclerosis, frontotemporal dementia, and spinocerebellar ataxia. Recent Findings RBPs are critical players in gene expression that regulate every step of posttranscriptional modifications. Recent genome-wide approaches revealed that many proteins associate with RNA, but do not contain any known RNA binding motifs. Additionally, many causal and risk genes of neurodevelopmental and neurodegenerative diseases are RBPs. Development of high-throughput sequencing methods has mapped out the fingerprints of RBPs on transcripts and provides unprecedented potential to discover new mechanisms of neurological diseases. Insights into how RBPs modulate neural development are important for designing effective therapies for numerous neurodevelopmental and neurodegenerative diseases. Summary RBPs have diverse mechanisms for modulating RNA processing and, thereby, controlling neurogenesis. Understanding the role of disease-associated RBPs in neurogenesis is vital for developing novel treatments for neurological diseases.
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Affiliation(s)
- Yijing Zhou
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Fengping Dong
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Yingwei Mao
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
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Scoles DR, Pulst SM. Spinocerebellar Ataxia Type 2. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1049:175-195. [PMID: 29427103 DOI: 10.1007/978-3-319-71779-1_8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is autosomal dominantly inherited and caused by CAG repeat expansion in the ATXN2 gene. Because the CAG repeat expansion is localized to an encoded region of ATXN2, the result is an expanded polyglutamine (polyQ) tract in the ATXN2 protein. SCA2 is characterized by progressive ataxia, and slow saccades. No treatment for SCA2 exists. ATXN2 mutation causes gains of new or toxic functions for the ATXN2 protein, resulting in abnormally slow Purkinje cell (PC) firing frequency and ultimately PC loss. This chapter describes the characteristics of SCA2 patients briefly, and reviews ATXN2 molecular features and progress toward the identification of a treatment for SCA2.
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Affiliation(s)
- Daniel R Scoles
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, UT, 84132, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, UT, 84132, USA.
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50
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Shenouda M, Zhang AB, Weichert A, Robertson J. Mechanisms Associated with TDP-43 Neurotoxicity in ALS/FTLD. ADVANCES IN NEUROBIOLOGY 2018; 20:239-263. [PMID: 29916022 DOI: 10.1007/978-3-319-89689-2_9] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The discovery of TDP-43 as a major disease protein in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) was first made in 2006. Prior to 2006 there were only 11 publications related to TDP-43, now there are over 2000, indicating the importance of TDP-43 to unraveling the complex molecular mechanisms that underpin the pathogenesis of ALS/FTLD. Subsequent to this discovery, TDP-43 pathology was also found in other neurodegenerative diseases, including Alzheimer's disease, the significance of which is still in the early stages of exploration. TDP-43 is a predominantly nuclear DNA/RNA-binding protein, one of a number of RNA-binding proteins that are now known to be linked with ALS/FTLD, including Fused in Sarcoma (FUS), heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1), and heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1). However, what sets TDP-43 apart is the vast number of cases in which TDP-43 pathology is present, providing a point of convergence, the understanding of which could lead to broadly applicable therapeutics. Here we will focus on TDP-43 in ALS/FTLD, its nuclear and cytoplasmic functions, and consequences should these functions go awry.
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Affiliation(s)
- Marc Shenouda
- Tanz Centre for Research in Neurodegenerative Diseases and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5T 2S8, Canada
| | - Ashley B Zhang
- Tanz Centre for Research in Neurodegenerative Diseases and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5T 2S8, Canada
| | - Anna Weichert
- Tanz Centre for Research in Neurodegenerative Diseases and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5T 2S8, Canada
| | - Janice Robertson
- Tanz Centre for Research in Neurodegenerative Diseases and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5T 2S8, Canada.
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