1
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Jafarinia H, van der Giessen E, Onck PR. C9orf72 polyPR directly binds to various nuclear transport components. eLife 2024; 12:RP89694. [PMID: 38483313 PMCID: PMC10939497 DOI: 10.7554/elife.89694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2024] Open
Abstract
The disruption of nucleocytoplasmic transport (NCT) is an important mechanism in neurodegenerative diseases. In the case of C9orf72-ALS, trafficking of macromolecules through the nuclear pore complex (NPC) might get frustrated by the binding of C9orf72-translated arginine-containing dipeptide repeat proteins (R-DPRs) to the Kapβ family of nuclear transport receptors. Besides Kapβs, several other types of transport components have been linked to NCT impairments in R-DPR-expressed cells, but the molecular origin of these observations has not been clarified. Here, we adopt a coarse-grained molecular dynamics model at amino acid resolution to study the direct interaction between polyPR, the most toxic DPR, and various nuclear transport components to elucidate the binding mechanisms and provide a complete picture of potential polyPR-mediated NCT defects. We found polyPR to directly bind to several isoforms of the Impα family, CAS (the specific exporter of Impα) and RanGAP. We observe no binding between polyPR and Ran. Longer polyPRs at lower salt concentrations also make contact with RanGEF and NTF2. Analyzing the polyPR contact sites on the transport components reveals that polyPR potentially interferes with RanGTP/RanGDP binding, with nuclear localization signal (NLS)-containing cargoes (cargo-NLS) binding to Impα, with cargo-NLS release from Impα, and with Impα export from the nucleus. The abundance of polyPR-binding sites on multiple transport components combined with the inherent polyPR length dependence makes direct polyPR interference of NCT a potential mechanistic pathway of C9orf72 toxicity.
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Affiliation(s)
- Hamidreza Jafarinia
- Zernike Institute for Advanced Materials, University of GroningenGroningenNetherlands
| | - Erik van der Giessen
- Zernike Institute for Advanced Materials, University of GroningenGroningenNetherlands
| | - Patrick R Onck
- Zernike Institute for Advanced Materials, University of GroningenGroningenNetherlands
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2
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Stringer RN, Weiss N. Pathophysiology of ion channels in amyotrophic lateral sclerosis. Mol Brain 2023; 16:82. [PMID: 38102715 PMCID: PMC10722804 DOI: 10.1186/s13041-023-01070-6] [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: 08/22/2023] [Accepted: 12/11/2023] [Indexed: 12/17/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) stands as the most prevalent and severe form of motor neuron disease, affecting an estimated 2 in 100,000 individuals worldwide. It is characterized by the progressive loss of cortical, brainstem, and spinal motor neurons, ultimately resulting in muscle weakness and death. Although the etiology of ALS remains poorly understood in most cases, the remodelling of ion channels and alteration in neuronal excitability represent a hallmark of the disease, manifesting not only during the symptomatic period but also in the early pre-symptomatic stages. In this review, we delve into these alterations observed in ALS patients and preclinical disease models, and explore their consequences on neuronal activities. Furthermore, we discuss the potential of ion channels as therapeutic targets in the context of ALS.
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Affiliation(s)
- Robin N Stringer
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Norbert Weiss
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic.
- Center of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia.
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3
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Morello G, La Cognata V, Guarnaccia M, La Bella V, Conforti FL, Cavallaro S. A Diagnostic Gene-Expression Signature in Fibroblasts of Amyotrophic Lateral Sclerosis. Cells 2023; 12:1884. [PMID: 37508548 PMCID: PMC10378077 DOI: 10.3390/cells12141884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/11/2023] [Accepted: 07/15/2023] [Indexed: 07/30/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease with limited treatment options. Diagnosis can be difficult due to the heterogeneity and non-specific nature of the initial symptoms, resulting in delays that compromise prompt access to effective therapeutic strategies. Transcriptome profiling of patient-derived peripheral cells represents a valuable benchmark in overcoming such challenges, providing the opportunity to identify molecular diagnostic signatures. In this study, we characterized transcriptome changes in skin fibroblasts of sporadic ALS patients (sALS) and controls and evaluated their utility as a molecular classifier for ALS diagnosis. Our analysis identified 277 differentially expressed transcripts predominantly involved in transcriptional regulation, synaptic transmission, and the inflammatory response. A support vector machine classifier based on this 277-gene signature was developed to discriminate patients with sALS from controls, showing significant predictive power in both the discovery dataset and in six independent publicly available gene expression datasets obtained from different sALS tissue/cell samples. Taken together, our findings support the utility of transcriptional signatures in peripheral cells as valuable biomarkers for the diagnosis of ALS.
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Affiliation(s)
- Giovanna Morello
- Institute for Biomedical Research and Innovation, National Research Council (CNR-IRIB), 95126 Catania, Italy
| | - Valentina La Cognata
- Institute for Biomedical Research and Innovation, National Research Council (CNR-IRIB), 95126 Catania, Italy
| | - Maria Guarnaccia
- Institute for Biomedical Research and Innovation, National Research Council (CNR-IRIB), 95126 Catania, Italy
| | - Vincenzo La Bella
- ALS Clinical Research Center and Neurochemistry Laboratory, BiND, University of Palermo, 90133 Palermo, Italy
| | - Francesca Luisa Conforti
- Medical Genetics Laboratory, Department of Pharmacy and Health and Nutritional Sciences, University of Calabria, 87036 Rende, Italy
| | - Sebastiano Cavallaro
- Institute for Biomedical Research and Innovation, National Research Council (CNR-IRIB), 95126 Catania, Italy
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4
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McGoldrick P, Lau A, You Z, Durcan TM, Robertson J. Loss of C9orf72 perturbs the Ran-GTPase gradient and nucleocytoplasmic transport, generating compositionally diverse Importin β-1 granules. Cell Rep 2023; 42:112134. [PMID: 36821445 DOI: 10.1016/j.celrep.2023.112134] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 10/05/2022] [Accepted: 01/31/2023] [Indexed: 02/24/2023] Open
Abstract
A hexanucleotide (GGGGCC)n repeat expansion in C9orf72 causes amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), eliciting toxic effects through generation of RNA foci, dipeptide repeat proteins, and/or loss of C9orf72 protein. Defects in nucleocytoplasmic transport (NCT) have been implicated as a pathogenic mechanism underlying repeat expansion toxicity. Here, we show that loss of C9orf72 disrupts the Ran-GTPase gradient and NCT in vitro and in vivo. NCT disruption in vivo is enhanced by the presence of compositionally different types of cytoplasmic Importin β-1 granule that exhibit neuronal subtype-specific properties. We show that the abundance of Importin β-1 granules is increased in the context of C9orf72 deficiency, disrupting interactions with nuclear pore complex proteins. These granules appear to associate with the nuclear envelope and are co-immunoreactive for G3BP1 and K63-ubiquitin. These findings link loss of C9orf72 protein to gain-of-function mechanisms and defects in NCT.
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Affiliation(s)
- Philip McGoldrick
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, 60 Leonard Avenue, Toronto, ON M5T 2S8, Canada.
| | - Agnes Lau
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, 60 Leonard Avenue, Toronto, ON M5T 2S8, Canada
| | - Zhipeng You
- The Neuro's Early Drug Discovery Unit (EDDU), McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada
| | - Thomas M Durcan
- The Neuro's Early Drug Discovery Unit (EDDU), McGill University, 3801 University Street, Montreal, QC H3A 2B4, Canada
| | - Janice Robertson
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, 60 Leonard Avenue, Toronto, ON M5T 2S8, Canada; Department of Laboratory Medicine and Pathobiology, 27 King's College Circle, Toronto, ON M5S 1A1, Canada.
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5
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Torres P, Cabral-Miranda F, Gonzalez-Teuber V, Hetz C. Proteostasis deregulation as a driver of C9ORF72 pathogenesis. J Neurochem 2021; 159:941-957. [PMID: 34679204 DOI: 10.1111/jnc.15529] [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: 09/04/2021] [Revised: 10/16/2021] [Accepted: 10/18/2021] [Indexed: 12/21/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are two related neurodegenerative disorders that display overlapping features. The hexanucleotide repeat expansion GGGGCC (G4 C2 ) in C9ORF72 gene has been causally linked to both ALS and FTD emergence, thus opening a novel potential therapeutic target for disease intervention. The main driver of C9ORF72 pathology is the disruption of distinct cellular processes involved in the function of the proteostasis network. Here we discuss main findings relating to the induction of neurodegeneration by C9ORF72 mutation and proteostasis deregulation, highlighting the role of the endoplasmic reticulum stress, nuclear transport, and autophagy in the disease process. We further discuss possible points of intervention to target proteostasis mediators to treat C9ORF72-linked ALS/FTD.
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Affiliation(s)
- Paulina Torres
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,FONDAP Center for Geroscience, Brain Health, and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Science, University of Chile, Santiago, Chile
| | - Felipe Cabral-Miranda
- Instituto de Ciências Biomédicas, Universidade do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Vicente Gonzalez-Teuber
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,FONDAP Center for Geroscience, Brain Health, and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Science, University of Chile, Santiago, Chile
| | - Claudio Hetz
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,FONDAP Center for Geroscience, Brain Health, and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Science, University of Chile, Santiago, Chile.,Buck Institute for Research on Aging, Novato, California, USA
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6
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Coyne AN, Baskerville V, Zaepfel BL, Dickson DW, Rigo F, Bennett F, Lusk CP, Rothstein JD. Nuclear accumulation of CHMP7 initiates nuclear pore complex injury and subsequent TDP-43 dysfunction in sporadic and familial ALS. Sci Transl Med 2021; 13:eabe1923. [PMID: 34321318 PMCID: PMC9022198 DOI: 10.1126/scitranslmed.abe1923] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 03/02/2021] [Accepted: 06/09/2021] [Indexed: 01/29/2023]
Abstract
Alterations in the components [nucleoporins (Nups)] and function of the nuclear pore complex (NPC) have been implicated as contributors to the pathogenesis of genetic forms of neurodegeneration including C9orf72 amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD). We hypothesized that Nup alterations and the consequential loss of NPC function may lie upstream of TDP-43 dysfunction and mislocalization widely observed in ALS, FTD, and related neurodegenerative diseases. Here, we provide evidence that CHMP7, a critical mediator of NPC quality control, is increased in nuclei of C9orf72 and sporadic ALS induced pluripotent stem cell (iPSC)-derived spinal neurons (iPSNs) and postmortem human motor cortex before the emergence of Nup alterations. Inhibiting the nuclear export of CHMP7 triggered Nup reduction and TDP-43 dysfunction and pathology in human neurons. Knockdown of CHMP7 alleviated disease-associated Nup alterations, deficits in Ran GTPase localization, defects in TDP-43-associated mRNA expression, and downstream glutamate-induced neuronal death. Thus, our data support a role for altered CHMP7-mediated Nup homeostasis as a prominent initiating pathological mechanism for familial and sporadic ALS and highlight the potential for CHMP7 as therapeutic target.
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Affiliation(s)
- Alyssa N Coyne
- Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Victoria Baskerville
- Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Benjamin L Zaepfel
- Biochemistry, Cellular, and Molecular Biology Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Dennis W Dickson
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, CA 92010, USA
| | | | - C Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Jeffrey D Rothstein
- Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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7
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Yoshizawa T, Guo L. Karyopherin-βs play a key role as a phase separation regulator. J Biochem 2021; 170:15-23. [PMID: 34223614 DOI: 10.1093/jb/mvab072] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/08/2021] [Indexed: 11/13/2022] Open
Abstract
Recent studies have revealed that cells utilize liquid-liquid phase separation (LLPS) as a mechanism in assembly of membrane-less organelles, such as RNP granules. The nucleus is a well-known membrane-bound organelle surrounded by the nuclear envelope; the nuclear pore complex on the nuclear envelope likely applies LLPS in the central channel to facilitate selective biological macromolecule exchange. Karyopherin-β family proteins exclusively pass through the central channel with cargos by dissolving the phase separated hydrogel formed by the phenylalanine-glycine (FG) repeats-containing nucleoporins. Karyopherin-βs also exhibit dissolution activity for the phase separation of cargo proteins. Many cargos, including RNA-binding proteins containing intrinsically disordered regions (IDRs), undergo phase separation; however, aberrant phase separation is linked to fatal neurodegenerative diseases. Multiple weak interactions between karyopherin-βs and phase separation-prone proteins, such as FG repeats-containing nucleoporins or IDR-containing karyopherin-β cargos, are likely to be important for passing through the nuclear pore complex and maintaining the soluble state of cargo, respectively. In this review, we discuss how karyopherin-βs regulate phase separation to function.
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Affiliation(s)
- Takuya Yoshizawa
- Department of Biotechnology, College of Life Sciences, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu-shi, Shiga 525-8577, Japan
| | - Lin Guo
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA 19107, USA
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8
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Nikbakhtzadeh M, Shaerzadeh F, Ashabi G. Highlighting the protective or degenerative role of AMPK activators in dementia experimental models. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2021; 20:786-801. [PMID: 34042039 DOI: 10.2174/1871527320666210526160214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 11/02/2020] [Accepted: 12/21/2020] [Indexed: 11/22/2022]
Abstract
AMP-activated protein kinase (AMPK) is a serine/threonine kinase and a driving or deterrent factor in the development of neurodegenerative diseases and dementia. AMPK affects intracellular proteins like the mammalian target of rapamycin (mTOR). Peroxisome proliferator-activated receptor-γ coactivator 1-α (among others) contributes to a wide range of intracellular activities based on its downstream molecules such as energy balancing (ATP synthesis), extracellular inflammation, cell growth, and neuronal cell death (such as apoptosis, necrosis, and necroptosis). Several studies have looked at the dual role of AMPK in neurodegenerative diseases such as Parkinson's disease (PD), Alzheimer's disease (AD), and Huntington disease (HD) but the exact effect of this enzyme on dementia, stroke, and motor neuron dysfunction disorders has not been elucidated yet. In this article, we review current research on the effects of AMPK on the brain to give an overview of the relationship. More specifically, we review the neuroprotective or neurodegenerative effects of AMPK or AMPK activators like metformin, resveratrol, and 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside on neurological diseases and dementia, which exert through the intracellular molecules involved in neuronal survival or death.
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Affiliation(s)
- Marjan Nikbakhtzadeh
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Fatemeh Shaerzadeh
- Department of Neuroscience, University of Florida College of Medicine and McKnight Brain Institute, Gainesville, United States
| | - Ghorbangol Ashabi
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
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9
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Low YH, Asi Y, Foti SC, Lashley T. Heterogeneous Nuclear Ribonucleoproteins: Implications in Neurological Diseases. Mol Neurobiol 2021; 58:631-646. [PMID: 33000450 PMCID: PMC7843550 DOI: 10.1007/s12035-020-02137-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/17/2020] [Indexed: 12/13/2022]
Abstract
Heterogenous nuclear ribonucleoproteins (hnRNPs) are a complex and functionally diverse family of RNA binding proteins with multifarious roles. They are involved, directly or indirectly, in alternative splicing, transcriptional and translational regulation, stress granule formation, cell cycle regulation, and axonal transport. It is unsurprising, given their heavy involvement in maintaining functional integrity of the cell, that their dysfunction has neurological implications. However, compared to their more established roles in cancer, the evidence of hnRNP implication in neurological diseases is still in its infancy. This review aims to consolidate the evidences for hnRNP involvement in neurological diseases, with a focus on spinal muscular atrophy (SMA), Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), multiple sclerosis (MS), congenital myasthenic syndrome (CMS), and fragile X-associated tremor/ataxia syndrome (FXTAS). Understanding more about hnRNP involvement in neurological diseases can further elucidate the pathomechanisms involved in these diseases and perhaps guide future therapeutic advances.
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Affiliation(s)
- Yi-Hua Low
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
- Duke-NUS Medical School, Singapore, Singapore
| | - Yasmine Asi
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Sandrine C Foti
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Tammaryn Lashley
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK.
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10
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Fortier G, Butti Z, Patten SA. Modelling C9orf72-Related Amyotrophic Lateral Sclerosis in Zebrafish. Biomedicines 2020; 8:E440. [PMID: 33096681 PMCID: PMC7589578 DOI: 10.3390/biomedicines8100440] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/16/2020] [Accepted: 10/17/2020] [Indexed: 12/12/2022] Open
Abstract
A hexanucleotide repeat expansion within the C9orf72 gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and its discovery has revolutionized our understanding of this devastating disease. Model systems are a valuable tool for studying ALS pathobiology and potential therapies. The zebrafish (Danio rerio) has particularly become a useful model organism to study neurological diseases, including ALS, due to high genetic and physiological homology to mammals, and sensitivity to various genetic and pharmacological manipulations. In this review we summarize the zebrafish models that have been used to study the pathology of C9orf72-related ALS. We discuss their value in providing mechanistic insights and their potential use for drug discovery.
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Affiliation(s)
- Gabrielle Fortier
- INRS-Centre Armand-Frappier Santé et Biotechnologie, Laval, QC H7V 1B7, Canada; (G.F.); (Z.B.)
| | - Zoé Butti
- INRS-Centre Armand-Frappier Santé et Biotechnologie, Laval, QC H7V 1B7, Canada; (G.F.); (Z.B.)
| | - Shunmoogum A. Patten
- INRS-Centre Armand-Frappier Santé et Biotechnologie, Laval, QC H7V 1B7, Canada; (G.F.); (Z.B.)
- Centre d’Excellence en Recherche sur les Maladies Orphelines—Fondation Courtois (CERMO-FC), Université du Québec à Montréal (UQAM), Montréal, QC H2X 3Y7, Canada
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11
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Gillon A, Steel C, Cornwall J, Sheard P. Increased nuclear permeability is a driver for age-related motoneuron loss. GeroScience 2020; 42:833-847. [PMID: 32002784 PMCID: PMC7286994 DOI: 10.1007/s11357-020-00155-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 01/09/2020] [Indexed: 12/11/2022] Open
Abstract
Sarcopenia is the loss of skeletal muscle mass with age, the precise cause of which remains unclear. Several studies have shown that sarcopenia is at least partly driven by denervation which, in turn, is related to loss of motor nerve cells. Recent data suggests degradation of the nucleocytoplasmic barrier and nuclear envelope transport process are contributors to nerve loss in a number of neurodegenerative diseases. Having recently shown that important components of the nuclear barrier are lost with advancing age, we now ask whether these emergent defects accompany increased nuclear permeability, chromatin disorganization and lower motoneuron loss in normal ageing, and if so, whether exercise attenuates these changes. Immunohistochemistry was used on young adult, old and exercised mouse tissues to examine nucleocytoplasmic transport regulatory proteins and chromatin organization. We used a nuclear permeability assay to investigate the patency of the nuclear barrier on extracts of the spinal cord from each group. We found increased permeability in nuclei isolated from spinal cords of old animals that correlated with both mislocalization of essential nuclear transport proteins and chromatin disorganization, and also found that in each case, exercise attenuated the age-associated changes. Findings suggest that the loss of nuclear barrier integrity in combination with previously described defects in nucleocytoplasmic transport may drive increased nuclear permeability and contribute to age-related motoneuron death. These events may be significant indirect drivers of skeletal muscle loss.
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Affiliation(s)
- Ashley Gillon
- Department of Physiology, School of Biomedical Sciences, University of Otago, P.O. Box 913, Dunedin, New Zealand
| | - Charlotte Steel
- Department of Physiology, School of Biomedical Sciences, University of Otago, P.O. Box 913, Dunedin, New Zealand
| | - Jon Cornwall
- Centre for Early Learning in Medicine, Otago Medical School, University of Otago, Dunedin, New Zealand
| | - Philip Sheard
- Department of Physiology, School of Biomedical Sciences, University of Otago, P.O. Box 913, Dunedin, New Zealand
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12
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Ishiguro A, Kimura N, Noma T, Shimo-Kon R, Ishihama A, Kon T. Molecular dissection of ALS-linked TDP-43 - involvement of the Gly-rich domain in interaction with G-quadruplex mRNA. FEBS Lett 2020; 594:2254-2265. [PMID: 32337711 DOI: 10.1002/1873-3468.13800] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/15/2020] [Accepted: 04/20/2020] [Indexed: 12/12/2022]
Abstract
TDP-43 is the major pathogenic protein of amyotrophic lateral sclerosis (ALS). Previously, we identified that TDP-43 interacts with G-quadruplex (G4)-containing RNA and is involved in their long-distance transport in neurons. For the molecular dissection of the TDP-43 and G4-RNA interaction, we analyzed it here in vitro and in cultured cells using a set of 10 mutant TDP-43 proteins from familial and sporadic ALS patients as well as using the TDP-43 C-terminal Gly-rich domain alone. Our results altogether indicate the involvement of the Gly-rich region of TDP-43 in the initial recognition and binding of G4-RNA, which then induces tight binding of TDP-43 with target RNAs, supposedly in conjunction with its RNA recognition motifs.
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Affiliation(s)
- Akira Ishiguro
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Japan
| | - Nobuyuki Kimura
- Section of Cell Biology and Pathology, Department of Alzheimer's Disease Research, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Takashi Noma
- Department of Biological Science, Graduate School of Science, and Faculty of Science Osaka University, Toyonaka, Japan
| | - Rieko Shimo-Kon
- Department of Biological Science, Graduate School of Science, and Faculty of Science Osaka University, Toyonaka, Japan
| | - Akira Ishihama
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Japan
| | - Takahide Kon
- Department of Biological Science, Graduate School of Science, and Faculty of Science Osaka University, Toyonaka, Japan
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13
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Moore S, Rabichow BE, Sattler R. The Hitchhiker's Guide to Nucleocytoplasmic Trafficking in Neurodegeneration. Neurochem Res 2020; 45:1306-1327. [PMID: 32086712 DOI: 10.1007/s11064-020-02989-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/12/2020] [Accepted: 02/14/2020] [Indexed: 12/12/2022]
Abstract
The widespread nature of nucleocytoplasmic trafficking defects and protein accumulation suggests distinct yet overlapping mechanisms in a variety of neurodegenerative diseases. Detailed understanding of the cellular pathways involved in nucleocytoplasmic transport and its dysregulation are essential for elucidating neurodegenerative pathogenesis and pinpointing potential areas for therapeutic intervention. The transport of cargos from the nucleus to the cytoplasm is generally regulated by the structure and function of the nuclear pore as well as the karyopherin α/β, importin, exportin, and mRNA export mechanisms. The disruption of these crucial transport mechanisms has been extensively described in the context of neurodegenerative diseases. One common theme in neurodegeneration is the cytoplasmic aggregation of proteins, including nuclear RNA binding proteins, repeat expansion associated gene products, and tau. These cytoplasmic aggregations are partly a consequence of failed nucleocytoplasmic transport machinery, but can also further disrupt transport, creating cyclical feed-forward mechanisms that exacerbate neurodegeneration. Here we describe the canonical mechanisms that regulate nucleocytoplasmic trafficking as well as how these mechanisms falter in neurodegenerative diseases.
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Affiliation(s)
- Stephen Moore
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Road, Phoenix, AZ, 85013, USA.,School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Benjamin E Rabichow
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Road, Phoenix, AZ, 85013, USA
| | - Rita Sattler
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Road, Phoenix, AZ, 85013, USA.
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14
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Schlachetzki JCM, Toda T, Mertens J. When function follows form: Nuclear compartment structure and the epigenetic landscape of the aging neuron. Exp Gerontol 2020; 133:110876. [PMID: 32068088 DOI: 10.1016/j.exger.2020.110876] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 01/29/2020] [Accepted: 02/10/2020] [Indexed: 12/21/2022]
Abstract
The human brain is affected by cellular aging. Neurons are primarily generated during embryogenesis and early life with a limited capacity for renewal and replacement, making them some of the oldest cells in the human body. Our present understanding of neurodegenerative diseases points towards advanced neuronal age as a prerequisite for the development of these disorders. While significant progress has been made in understanding the relationship between aging and neurological disease, it will be essential to delve further into the molecular mechanisms of neuronal aging in order to develop therapeutic interventions targeting age-related brain dysfunction. In this mini review, we highlight recent findings on the relationship between the aging of nuclear structures and changes in the epigenetic landscape during neuronal aging and disease.
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Affiliation(s)
- Johannes C M Schlachetzki
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
| | - Tomohisa Toda
- Nuclear Architecture in Neural Plasticity and Aging, German Center for Neurodegenerative Diseases (DZNE), Dresden, Germany.
| | - Jerome Mertens
- Institute of Molecular Biology & CMBI, Leopold-Franzens-University Innsbruck, Austria; Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA, USA.
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15
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Tabassum R, Jeong NY, Jung J. Protective effect of hydrogen sulfide on oxidative stress-induced neurodegenerative diseases. Neural Regen Res 2020; 15:232-241. [PMID: 31552888 PMCID: PMC6905340 DOI: 10.4103/1673-5374.265543] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 06/06/2019] [Indexed: 12/11/2022] Open
Abstract
Hydrogen sulfide is an antioxidant molecule that has a wide range of biological effects against oxidative stress. Balanced oxidative stress is also vital for maintaining cellular function in biological system, where reactive oxygen species are the main source of oxidative stress. When the normal redox balance is disturbed, deoxyribonucleic acid, lipid, and protein molecules are oxidized under pathological conditions, like diabetes mellitus that leads to diabetic peripheral neuropathy. In diabetes mellitus-induced diabetic peripheral neuropathy, due to hyperglycemia, pancreatic beta cell (β cell) shows resistance to insulin secretion. As a consequence, glucose metabolism is disturbed in neuronal cells which are distracted from providing proper cell signaling pathway. Not only diabetic peripheral neuropathy but also other central damages occur in brain neuropathy. Neurological studies regarding type 1 diabetes mellitus patients with Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis have shown changes in the central nervous system because high blood glucose levels (HbA1c) appeared with poor cognitive function. Oxidative stress plays a role in inhibiting insulin signaling that is necessary for brain function. Hydrogen sulfide exhibits antioxidant effects against oxidative stress, where cystathionine β synthase, cystathionine γ lyase, and 3-mercaptopyruvate sulfurtransferase are the endogenous sources of hydrogen sulfide. This review is to explore the pathogenesis of diabetes mellitus-induced diabetic peripheral neuropathy and other neurological comorbid disorders under the oxidative stress condition and the anti-oxidative effects of hydrogen sulfide.
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Affiliation(s)
- Rubaiya Tabassum
- Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Seo-gu, Busan, Korea
- Department of Medicine, Graduate School, Dong-A University, Seo-gu, Busan, Korea
| | - Na Young Jeong
- Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Seo-gu, Busan, Korea
- Department of Medicine, Graduate School, Dong-A University, Seo-gu, Busan, Korea
| | - Junyang Jung
- Department of Anatomy and Neurobiology, College of Medicine, Kyung Hee University, Dongdaemun-gu, Seoul, Korea
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16
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Park S, Park SK, Watanabe N, Hashimoto T, Iwatsubo T, Shelkovnikova TA, Liebman SW. Calcium-responsive transactivator (CREST) toxicity is rescued by loss of PBP1/ATXN2 function in a novel yeast proteinopathy model and in transgenic flies. PLoS Genet 2019; 15:e1008308. [PMID: 31390360 PMCID: PMC6699716 DOI: 10.1371/journal.pgen.1008308] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 08/19/2019] [Accepted: 07/12/2019] [Indexed: 12/26/2022] Open
Abstract
Proteins associated with familial neurodegenerative disease often aggregate in patients’ neurons. Several such proteins, e.g. TDP-43, aggregate and are toxic when expressed in yeast. Deletion of the ATXN2 ortholog, PBP1, reduces yeast TDP-43 toxicity, which led to identification of ATXN2 as an amyotrophic lateral sclerosis (ALS) risk factor and therapeutic target. Likewise, new yeast neurodegenerative disease models could facilitate identification of other risk factors and targets. Mutations in SS18L1, encoding the calcium-responsive transactivator (CREST) chromatin-remodeling protein, are associated with ALS. We show that CREST is toxic in yeast and forms nuclear and occasionally cytoplasmic foci that stain with Thioflavin-T, a dye indicative of amyloid-like protein. Like the yeast chromatin-remodeling factor SWI1, CREST inhibits silencing of FLO genes. Toxicity of CREST is enhanced by the [PIN+] prion and reduced by deletion of the HSP104 chaperone required for the propagation of many yeast prions. Likewise, deletion of PBP1 reduced CREST toxicity and aggregation. In accord with the yeast data, we show that the Drosophila ortholog of human ATXN2, dAtx2, is a potent enhancer of CREST toxicity. Downregulation of dAtx2 in flies overexpressing CREST in retinal ganglion cells was sufficient to largely rescue the severe degenerative phenotype induced by human CREST. Overexpression caused considerable co-localization of CREST and PBP1/ATXN2 in cytoplasmic foci in both yeast and mammalian cells. Thus, co-aggregation of CREST and PBP1/ATXN2 may serve as one of the mechanisms of PBP1/ATXN2-mediated toxicity. These results extend the spectrum of ALS associated proteins whose toxicity is regulated by PBP1/ATXN2, suggesting that therapies targeting ATXN2 may be effective for a wide range of neurodegenerative diseases. Mutations in the calcium-responsive transactivator (CREST) protein have been shown to cause amyotrophic lateral sclerosis (ALS). Here we show that the human CREST protein expressed in yeast forms largely nuclear aggregates and is toxic. We also show that the HSP104 chaperone required for propagation of yeast prions is likewise required for CREST toxicity. Furthermore deletion of HSP104 affects CREST aggregation. ATXN2, previously shown to modify ALS toxicity caused by mutations in the TDP-43 encoding gene, also modifies toxicity of CREST expressed in either yeast or flies. In addition, deletion of the yeast ATXN2 ortholog reduces CREST aggregation. These results extend the spectrum of ALS associated proteins whose toxicity is regulated by ATXN2, suggesting that therapies targeting ATXN2 may be effective for a wide range of neurodegenerative diseases.
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Affiliation(s)
- Sangeun Park
- Department of Pharmacology, University of Nevada, Reno, Untied States of America
| | - Sei-Kyoung Park
- Department of Pharmacology, University of Nevada, Reno, Untied States of America
| | | | | | | | | | - Susan W. Liebman
- Department of Pharmacology, University of Nevada, Reno, Untied States of America
- * E-mail:
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17
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Chi B, O'Connell JD, Iocolano AD, Coady JA, Yu Y, Gangopadhyay J, Gygi SP, Reed R. The neurodegenerative diseases ALS and SMA are linked at the molecular level via the ASC-1 complex. Nucleic Acids Res 2019; 46:11939-11951. [PMID: 30398641 PMCID: PMC6294556 DOI: 10.1093/nar/gky1093] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 10/19/2018] [Indexed: 12/12/2022] Open
Abstract
Understanding the molecular pathways disrupted in motor neuron diseases is urgently needed. Here, we employed CRISPR knockout (KO) to investigate the functions of four ALS-causative RNA/DNA binding proteins (FUS, EWSR1, TAF15 and MATR3) within the RNAP II/U1 snRNP machinery. We found that each of these structurally related proteins has distinct roles with FUS KO resulting in loss of U1 snRNP and the SMN complex, EWSR1 KO causing dissociation of the tRNA ligase complex, and TAF15 KO resulting in loss of transcription factors P-TEFb and TFIIF. However, all four ALS-causative proteins are required for association of the ASC-1 transcriptional co-activator complex with the RNAP II/U1 snRNP machinery. Remarkably, mutations in the ASC-1 complex are known to cause a severe form of Spinal Muscular Atrophy (SMA), and we show that an SMA-causative mutation in an ASC-1 component or an ALS-causative mutation in FUS disrupts association between the ASC-1 complex and the RNAP II/U1 snRNP machinery. We conclude that ALS and SMA are more intimately tied to one another than previously thought, being linked via the ASC-1 complex.
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Affiliation(s)
- Binkai Chi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave. Boston MA 02115, USA
| | - Jeremy D O'Connell
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave. Boston MA 02115, USA
| | - Alexander D Iocolano
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave. Boston MA 02115, USA
| | - Jordan A Coady
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave. Boston MA 02115, USA
| | - Yong Yu
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave. Boston MA 02115, USA
| | - Jaya Gangopadhyay
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave. Boston MA 02115, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave. Boston MA 02115, USA
| | - Robin Reed
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave. Boston MA 02115, USA
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18
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Alonso R, Pisa D, Carrasco L. Searching for Bacteria in Neural Tissue From Amyotrophic Lateral Sclerosis. Front Neurosci 2019; 13:171. [PMID: 30863279 PMCID: PMC6399391 DOI: 10.3389/fnins.2019.00171] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 02/13/2019] [Indexed: 12/28/2022] Open
Abstract
Despite great efforts in the investigation, the exact etiology of amyotrophic lateral sclerosis (ALS) is a matter of intensive research. We recently advanced the idea that ALS might be caused by fungal infection. Indeed, fungal yeast and hyphal structures can be directly visualized in neural tissue of ALS patients, and a number of fungal species have been identified in the central nervous system (CNS). In the present work, we tested the possibility that bacterial infections can accompany these mycoses. Our findings establish the presence of bacterial DNA in different regions of the CNS from all ALS patients examined. Specifically, we used PCR and next generation sequencing (NGS) to precisely determine the bacterial species present in ALS tissue. Consistent with these findings, immunohistochemistry analysis of CNS sections using specific anti-bacterial antibodies identified prokaryotic cells in neural tissue. Finally, we assayed for the repeat expansion of the hexanucleotide repeat GGGGCC in C9orf72, which is considered the most common genetic cause of ALS in patients, using DNA extracted from ALS CNS tissue. We failed to find this repeated sequence in any of the eleven patients analyzed. Our results indicate that bacterial DNA and prokaryotic cells are present in CNS tissue, leading to the concept that both fungal and bacterial infections coexist in patients with ALS. These observations lay the groundwork for the use of appropriate therapies to eradicate the polymicrobial infections in ALS.
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Affiliation(s)
- Ruth Alonso
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Diana Pisa
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Luis Carrasco
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
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19
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Guo L, Fare CM, Shorter J. Therapeutic Dissolution of Aberrant Phases by Nuclear-Import Receptors. Trends Cell Biol 2019; 29:308-322. [PMID: 30660504 DOI: 10.1016/j.tcb.2018.12.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 12/11/2018] [Accepted: 12/14/2018] [Indexed: 12/14/2022]
Abstract
Nuclear-import receptors (NIRs) bind nuclear-localization signals (NLSs) of protein cargo in the cytoplasm and transport them into the nucleus. Here, we review advances establishing that NIRs also function in the cytoplasm to prevent and reverse functional and aberrant phase transitions of their cargo, including neurodegenerative disease-linked RNA-binding proteins (RBPs) with prion-like domains, such as TDP-43, FUS, hnRNPA1, and hnRNPA2. NIRs selectively extract cargo from condensed liquid phases thereby regulating functional phase separation. Consequently, NIRs sculpt cytoplasmic membraneless organelles and regulate cellular organization beyond their canonical role in nuclear import. Elevating NIR expression dissolves cytoplasmic RBP aggregates, restores functional RBPs to the nucleus, and rescues disease-linked RBP toxicity. Thus, NIRs could be leveraged therapeutically to restore RBP homeostasis and mitigate neurodegeneration.
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Affiliation(s)
- Lin Guo
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Joint first authors
| | - Charlotte M Fare
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Joint first authors
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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20
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Tavolieri MV, Droppelmann CA, Campos-Melo D, Volkening K, Strong MJ. A novel overlapping NLS/NES region within the PH domain of Rho Guanine Nucleotide Exchange Factor (RGNEF) regulates its nuclear-cytoplasmic localization. Eur J Cell Biol 2019; 98:27-35. [PMID: 30482479 DOI: 10.1016/j.ejcb.2018.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 10/08/2018] [Accepted: 11/13/2018] [Indexed: 10/27/2022] Open
Abstract
Rho Guanine Nucleotide Exchange Factor (RGNEF) is a 190 kDa protein implicated in both amyotrophic lateral sclerosis (ALS) and cancer. Under normal physiological conditions, RGNEF is predominantly cytoplasmic with moderate levels of nuclear localization. We have identified a 23-amino acid region containing a bipartite nuclear localization signal (NLS) within the Pleckstrin Homology (PH) domain of RGNEF, which when deleted or mutated abolishes the nuclear localization of this protein. Fusion proteins containing only the PH domain demonstrated that this region by itself is able to translocate a 160 kDa protein to the nucleus. Interestingly, we also detected a nuclear export signal (NES) within the linker region of this bipartite NLS which is able to export from the nucleus a fusion protein containing two NLSs. Experiments using Leptomycin-B -an inhibitor of nuclear export- confirmed that this region promotes nuclear export in an exportin-1 dependent manner. This study is the first report demonstrating either of these signals embedded within a PH domain. Notably, this is also the first description of a functional overlapped NLS/NES signal.
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Affiliation(s)
- Michael V Tavolieri
- Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
| | - Cristian A Droppelmann
- Molecular Medicine Group, Robarts Research Institute, Western University, London, Ontario, Canada.
| | - Danae Campos-Melo
- Molecular Medicine Group, Robarts Research Institute, Western University, London, Ontario, Canada.
| | - Kathryn Volkening
- Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Molecular Medicine Group, Robarts Research Institute, Western University, London, Ontario, Canada.
| | - Michael J Strong
- Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Molecular Medicine Group, Robarts Research Institute, Western University, London, Ontario, Canada.
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21
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Patient-derived frontotemporal lobar degeneration brain extracts induce formation and spreading of TDP-43 pathology in vivo. Nat Commun 2018; 9:4220. [PMID: 30310141 PMCID: PMC6181940 DOI: 10.1038/s41467-018-06548-9] [Citation(s) in RCA: 152] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/14/2018] [Indexed: 12/12/2022] Open
Abstract
The stereotypical distribution of TAR DNA-binding 43 protein (TDP-43) aggregates in frontotemporal lobar degeneration (FTLD-TDP) suggests that pathological TDP-43 spreads throughout the brain via cell-to-cell transmission and correlates with disease progression, but no in vivo experimental data support this hypothesis. We first develop a doxycycline-inducible cell line expressing GFP-tagged cytoplasmic TDP-43 protein (iGFP-NLSm) as a cell-based system to screen and identify seeding activity of human brain-derived pathological TDP-43 isolated from sporadic FTLD-TDP and familial cases with Granulin (FTLD-TDP-GRN) or C9orf72 repeat expansion mutations (FTLD-TDP-C9+). We demonstrate that intracerebral injections of biologically active pathogenic FTLD-TDP seeds into transgenic mice expressing cytoplasmic human TDP-43 (lines CamKIIa-hTDP-43NLSm, rNLS8, and CamKIIa-208) and non-transgenic mice led to the induction of de-novo TDP-43 pathology. Moreover, TDP-43 pathology progressively spreads throughout the brain in a time-dependent manner via the neuroanatomic connectome. Our study suggests that the progression of FTLD-TDP reflects the templated cell-to-cell transneuronal spread of pathological TDP-43.
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22
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Mertens J, Reid D, Lau S, Kim Y, Gage FH. Aging in a Dish: iPSC-Derived and Directly Induced Neurons for Studying Brain Aging and Age-Related Neurodegenerative Diseases. Annu Rev Genet 2018; 52:271-293. [PMID: 30208291 DOI: 10.1146/annurev-genet-120417-031534] [Citation(s) in RCA: 184] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Age-associated neurological diseases represent a profound challenge in biomedical research as we are still struggling to understand the interface between the aging process and the manifestation of disease. Various pathologies in the elderly do not directly result from genetic mutations, toxins, or infectious agents but are primarily driven by the many manifestations of biological aging. Therefore, the generation of appropriate model systems to study human aging in the nervous system demands new concepts that lie beyond transgenic and drug-induced models. Although access to viable human brain specimens is limited and induced pluripotent stem cell models face limitations due to reprogramming-associated cellular rejuvenation, the direct conversion of somatic cells into induced neurons allows for the generation of human neurons that capture many aspects of aging. Here, we review advances in exploring age-associated neurodegenerative diseases using human cell reprogramming models, and we discuss general concepts, promises, and limitations of the field.
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Affiliation(s)
- Jerome Mertens
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA; .,Department of Genomics, Stem Cell Biology and Regenerative Medicine, Institute of Molecular Biology, and Center for Molecular Biosciences Innsbruck, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Dylan Reid
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
| | - Shong Lau
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
| | - Yongsung Kim
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
| | - Fred H Gage
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
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23
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Interactome analyses revealed that the U1 snRNP machinery overlaps extensively with the RNAP II machinery and contains multiple ALS/SMA-causative proteins. Sci Rep 2018; 8:8755. [PMID: 29884807 PMCID: PMC5993797 DOI: 10.1038/s41598-018-27136-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 05/24/2018] [Indexed: 12/12/2022] Open
Abstract
Mutations in multiple RNA/DNA binding proteins cause Amyotrophic Lateral Sclerosis (ALS). Included among these are the three members of the FET family (FUS, EWSR1 and TAF15) and the structurally similar MATR3. Here, we characterized the interactomes of these four proteins, revealing that they largely have unique interactors, but share in common an association with U1 snRNP. The latter observation led us to analyze the interactome of the U1 snRNP machinery. Surprisingly, this analysis revealed the interactome contains ~220 components, and of these, >200 are shared with the RNA polymerase II (RNAP II) machinery. Among the shared components are multiple ALS and Spinal muscular Atrophy (SMA)-causative proteins and numerous discrete complexes, including the SMN complex, transcription factor complexes, and RNA processing complexes. Together, our data indicate that the RNAP II/U1 snRNP machinery functions in a wide variety of molecular pathways, and these pathways are candidates for playing roles in ALS/SMA pathogenesis.
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24
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Scherz B, Rabl R, Flunkert S, Rohler S, Neddens J, Taub N, Temmel M, Panzenboeck U, Niederkofler V, Zimmermann R, Hutter-Paier B. mTh1 driven expression of hTDP-43 results in typical ALS/FTLD neuropathological symptoms. PLoS One 2018; 13:e0197674. [PMID: 29787578 PMCID: PMC5963763 DOI: 10.1371/journal.pone.0197674] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 05/07/2018] [Indexed: 12/12/2022] Open
Abstract
Transgenic mouse models are indispensable tools to mimic human diseases and analyze the effectiveness of related new drugs. For a long time amyotrophic lateral sclerosis (ALS) research depended on only a few mouse models that exhibit a very strong and early phenotype, e.g. SOD1 mice, resulting in a short treatment time window. By now, several models are available that need to be characterized to highlight characteristics of each model. Here we further characterized the mThy1-hTDP-43 transgenic mouse model TAR6/6 that overexpresses wild type human TARDBP, also called TDP-43, under control of the neuronal Thy-1 promoter presented by Wils and colleagues, 2010, by using biochemical, histological and behavioral readouts. Our results show that TAR6/6 mice exhibit a strong TDP-43 expression in the hippocampus, spinal cord, hypothalamus and medulla oblongata. Apart from prominent protein expression in the nucleus, TDP-43 protein was found at lower levels in the cytosol of transgenic mice. Additionally, we detected insoluble TDP-43 in the cortex, motoneuron loss, and increased neuroinflammation in the central nervous system of TAR6/6 animals. Behavioral analyses revealed early motor deficits in the clasping- and wire suspension test as well as decreased anxiety in the elevated plus maze. Further motor tests showed differences at later time points compared to non-transgenic littermates, thus allowing the observation of onset and severity of such deficits. Together, TAR6/6 mice are a valuable tool to test new ALS/FTLD drugs that target TDP-43 expression and insolubility, neuroinflammation, motoneuron loss or other TDP-43 related downstream signaling pathways since these mice exhibit a later pathology as previously used ALS/FTLD mouse models.
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Affiliation(s)
- Barbara Scherz
- QPS Austria GmbH, Grambach, Austria
- Karl-Franzens University, Institute of Molecular Biosciences, Graz, Austria
| | | | | | - Siegfried Rohler
- Medical University Graz, Institute of Pathophysiology and Immunology, Graz, Austria
| | | | | | | | - Ute Panzenboeck
- Medical University Graz, Institute of Pathophysiology and Immunology, Graz, Austria
| | | | - Robert Zimmermann
- Karl-Franzens University, Institute of Molecular Biosciences, Graz, Austria
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25
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Gillon A, Nielsen K, Steel C, Cornwall J, Sheard P. Exercise attenuates age-associated changes in motoneuron number, nucleocytoplasmic transport proteins and neuromuscular health. GeroScience 2018; 40:177-192. [PMID: 29736782 DOI: 10.1007/s11357-018-0020-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 04/17/2018] [Indexed: 12/31/2022] Open
Abstract
Life expectancy continues to extend, although frailty caused by loss of skeletal muscle mass continues unimpeded. Muscle atrophy caused by withdrawal of motor nerves is a feature of old age, as it is in amyotrophic lateral sclerosis (ALS) in which skeletal muscle denervation results from motoneuron death. In ALS, direct links have been established between motoneuron death and altered nucleocytoplasmic transport, so we ask whether similar defects accompany motoneuron death in normal ageing. We used immunohistochemistry on mouse tissues to explore potential links between neuromuscular junction (NMJ) degeneration, motoneuron death and nucleocytoplasmic transport regulatory proteins. Old age brought neuromuscular degeneration, motoneuron loss and reductions in immunodetectable levels of key nucleocytoplasmic transport proteins in lumbar motoneurons. We then asked whether exercise inhibited these changes and found that active elderly mice experienced less motoneuron death, improved neuromuscular junction morphology and retention of key nucleocytoplasmic transport proteins in lumbar motoneurons. Our results suggest that emergent defects in nucleocytoplasmic transport may contribute to motoneuron death and age-related loss of skeletal muscle mass, and that these defects may be reduced by exercise.
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Affiliation(s)
- Ashley Gillon
- Department of Physiology, School of Biomedical Sciences, University of Otago, P.O. Box 913, Dunedin, New Zealand.
| | - Kathrine Nielsen
- Department of Physiology, School of Biomedical Sciences, University of Otago, P.O. Box 913, Dunedin, New Zealand
| | - Charlotte Steel
- Department of Physiology, School of Biomedical Sciences, University of Otago, P.O. Box 913, Dunedin, New Zealand
| | - Jon Cornwall
- Otago Medical School, University of Otago, Dunedin, New Zealand
| | - Philip Sheard
- Department of Physiology, School of Biomedical Sciences, University of Otago, P.O. Box 913, Dunedin, New Zealand
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26
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Ederle H, Funk C, Abou-Ajram C, Hutten S, Funk EBE, Kehlenbach RH, Bailer SM, Dormann D. Nuclear egress of TDP-43 and FUS occurs independently of Exportin-1/CRM1. Sci Rep 2018; 8:7084. [PMID: 29728564 PMCID: PMC5935713 DOI: 10.1038/s41598-018-25007-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 04/13/2018] [Indexed: 12/11/2022] Open
Abstract
TDP-43 and FUS are nuclear proteins with multiple functions in mRNA processing. They play key roles in ALS (amyotrophic lateral sclerosis) and FTD (frontotemporal dementia), where they are partially lost from the nucleus and aggregate in the cytoplasm of neurons and glial cells. Defects in nucleocytoplasmic transport contribute to this pathology, hence nuclear import of both proteins has been studied in detail. However, their nuclear export routes remain poorly characterized and it is unclear whether aberrant nuclear export contributes to TDP-43 or FUS pathology. Here we show that predicted nuclear export signals in TDP-43 and FUS are non-functional and that both proteins are exported independently of the export receptor CRM1/Exportin-1. Silencing of Exportin-5 or the mRNA export factor Aly/REF, as well as mutations that abrogate RNA-binding do not impair export of TDP-43 and FUS. However, artificially enlarging TDP-43 or FUS impairs their nuclear egress, suggesting that they could leave the nucleus by passive diffusion. Finally, we found that inhibition of transcription causes accelerated nuclear egress of TDP-43, suggesting that newly synthesized RNA retains TDP-43 in the nucleus, limiting its egress into the cytoplasm. Our findings implicate reduced nuclear retention as a possible factor contributing to mislocalization of TDP-43 in ALS/FTD.
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Affiliation(s)
- Helena Ederle
- BioMedical Center (BMC), Cell Biology, Ludwig-Maximilians-University Munich, 82152, Planegg-Martinsried, Germany
- Graduate School of Systemic Neurosciences (GSN), 82152, Planegg-Martinsried, Germany
| | - Christina Funk
- Institute for Interfacial Engineering and Plasma Technology IGVP, University of Stuttgart, 70569, Stuttgart, Germany
- Frauenhofer Institute for Interfacial Engineering and Biotechnology, 70569, Stuttgart, Germany
| | - Claudia Abou-Ajram
- BioMedical Center (BMC), Cell Biology, Ludwig-Maximilians-University Munich, 82152, Planegg-Martinsried, Germany
| | - Saskia Hutten
- BioMedical Center (BMC), Cell Biology, Ludwig-Maximilians-University Munich, 82152, Planegg-Martinsried, Germany
| | - Eva B E Funk
- BioMedical Center (BMC), Biochemistry, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Ralph H Kehlenbach
- Department of Molecular Biology, Faculty of Medicine, GZMB, Georg-August-University Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Susanne M Bailer
- Institute for Interfacial Engineering and Plasma Technology IGVP, University of Stuttgart, 70569, Stuttgart, Germany
- Frauenhofer Institute for Interfacial Engineering and Biotechnology, 70569, Stuttgart, Germany
| | - Dorothee Dormann
- BioMedical Center (BMC), Cell Biology, Ludwig-Maximilians-University Munich, 82152, Planegg-Martinsried, Germany.
- Graduate School of Systemic Neurosciences (GSN), 82152, Planegg-Martinsried, Germany.
- Munich Cluster for Systems Neurology (SyNergy), 81377, Munich, Germany.
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27
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Cascarina SM, Paul KR, Ross ED. Manipulating the aggregation activity of human prion-like proteins. Prion 2018; 11:323-331. [PMID: 28934062 DOI: 10.1080/19336896.2017.1356560] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Considerable advances in understanding the protein features favoring prion formation in yeast have facilitated the development of effective yeast prion prediction algorithms. Here we discuss a recent study in which we systematically explored the utility of the yeast prion prediction algorithm PAPA for designing mutations to modulate the aggregation activity of the human prion-like protein hnRNPA2B1. Mutations in hnRNPA2B1 cause multisystem proteinopathy in humans, and accelerate aggregation of the protein in vitro. Additionally, mutant hnRNPA2B1 forms cytoplasmic inclusions when expressed in Drosophila, and the mutant prion-like domain can substitute for a portion of a yeast prion domain in supporting prion activity in yeast. PAPA was quite successful at predicting the effects of PrLD mutations on prion activity in yeast and on in vitro aggregation propensity. Additionally, PAPA successfully predicted the effects of most, but not all, mutations in the PrLD of the hnRNPA2B1 protein when expressed in Drosophila. These results suggest that PAPA is quite effective at predicting the effects of mutations on intrinsic aggregation propensity, but that intracellular factors can influence aggregation and prion-like activity in vivo. A more complete understanding of these intracellular factors may inform the next generation of prion prediction algorithms.
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Affiliation(s)
- Sean M Cascarina
- a Department of Biochemistry and Molecular Biology , Colorado State University , Fort Collins , CO , USA
| | - Kacy R Paul
- a Department of Biochemistry and Molecular Biology , Colorado State University , Fort Collins , CO , USA
| | - Eric D Ross
- a Department of Biochemistry and Molecular Biology , Colorado State University , Fort Collins , CO , USA
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28
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Alonso R, Pisa D, Fernández-Fernández AM, Rábano A, Carrasco L. Fungal infection in neural tissue of patients with amyotrophic lateral sclerosis. Neurobiol Dis 2017; 108:249-260. [DOI: 10.1016/j.nbd.2017.09.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 08/24/2017] [Accepted: 09/03/2017] [Indexed: 12/11/2022] Open
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29
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Haass C, Neumann M. Frontotemporal dementia: from molecular mechanisms to therapy. J Neurochem 2017; 138 Suppl 1:3-5. [PMID: 27502123 DOI: 10.1111/jnc.13619] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 03/11/2016] [Accepted: 03/12/2016] [Indexed: 12/14/2022]
Abstract
Frontotemporal dementia (FTD) is a heterogeneous clinical syndrome characterized by frontotemporal lobar degeneration (FTLD). Neuropathologically, FTLD is characterized by abnormal protein deposits and almost all cases can now be classified into three major molecular subgroups based on specific accumulating proteins with the most common being FTLD-tau and FTLD-TDP (accounting for ~40% and 50%, respectively) and FTLD-FET (accounting for ~5-10%). In this special issue, the molecular and genetic basics as well as clinical approaches and therapeutics are reviewed in a series of articles. This article is part of the Frontotemporal Dementia special issue.
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Affiliation(s)
- Christian Haass
- BioMedical Center (BMC), Biochemistry, Ludwig-Maximilians-University Munich, Munich, Germany.,German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Manuela Neumann
- Department for Neuropathology, University Hospital of Tübingen, Tübingen, Germany.,German Center for Neurodegenerative Diseases (DZNE) Tübingen, Tübingen, Germany
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30
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Sakuma S, D'Angelo MA. The roles of the nuclear pore complex in cellular dysfunction, aging and disease. Semin Cell Dev Biol 2017; 68:72-84. [PMID: 28506892 DOI: 10.1016/j.semcdb.2017.05.006] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 05/11/2017] [Indexed: 12/19/2022]
Abstract
The study of the Nuclear Pore Complex (NPC), the proteins that compose it (nucleoporins), and the nucleocytoplasmic transport that it controls have revealed an unexpected layer to pathogenic disease onset and progression. Recent advances in the study of the regulation of NPC composition and function suggest that the precise control of this structure is necessary to prevent diseases from arising or progressing. Here we discuss the role of nucleoporins in a diverse set of diseases, many of which directly or indirectly increase in occurrence and severity as we age, and often shorten the human lifespan. NPC biology has been shown to play a direct role in these diseases and therefore in the process of healthy aging.
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Affiliation(s)
- Stephen Sakuma
- Development, Aging and Regeneration Program (DARe), Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Maximiliano A D'Angelo
- Development, Aging and Regeneration Program (DARe), Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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31
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Liu YJ, Tsai PY, Chern Y. Energy Homeostasis and Abnormal RNA Metabolism in Amyotrophic Lateral Sclerosis. Front Cell Neurosci 2017; 11:126. [PMID: 28522961 PMCID: PMC5415567 DOI: 10.3389/fncel.2017.00126] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 04/18/2017] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease that is clinically characterized by progressive muscle weakness and impaired voluntary movement due to the loss of motor neurons in the brain, brain stem and spinal cord. To date, no effective treatment is available. Ample evidence suggests that impaired RNA homeostasis and abnormal energy status are two major pathogenesis pathways in ALS. In the present review article, we focus on recent studies that report molecular insights of both pathways, and discuss the possibility that energy dysfunction might negatively regulate RNA homeostasis via the impairment of cytoplasmic-nuclear shuttling in motor neurons and subsequently contribute to the development of ALS.
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Affiliation(s)
- Yu-Ju Liu
- Division of Neuroscience, Institute of Biomedical Sciences, Academia SinicaTaipei, Taiwan
| | - Po-Yi Tsai
- Division of Neuroscience, Institute of Biomedical Sciences, Academia SinicaTaipei, Taiwan
| | - Yijuang Chern
- Division of Neuroscience, Institute of Biomedical Sciences, Academia SinicaTaipei, Taiwan
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32
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Ederle H, Dormann D. TDP-43 and FUS en route from the nucleus to the cytoplasm. FEBS Lett 2017; 591:1489-1507. [PMID: 28380257 DOI: 10.1002/1873-3468.12646] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 03/24/2017] [Accepted: 04/02/2017] [Indexed: 12/13/2022]
Abstract
Misfolded or mislocalized RNA-binding proteins (RBPs) and, consequently, altered mRNA processing, can cause neuronal dysfunction, eventually leading to neurodegeneration. Two prominent examples are the RBPs TAR DNA-binding protein of 43 kDa (TDP-43) and fused in sarcoma (FUS), which form pathological messenger ribonucleoprotein aggregates in patients suffering from amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two devastating neurodegenerative disorders. Here, we review the multiple functions of TDP-43 and FUS in mRNA processing, both in the nucleus and in the cytoplasm. We discuss how TDP-43 and FUS may exit the nucleus and how defects in both nuclear and cytosolic mRNA processing events, and possibly nuclear export defects, may contribute to neurodegeneration and ALS/FTD pathogenesis.
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Affiliation(s)
- Helena Ederle
- BioMedical Center (BMC), Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany.,Graduate School of Systemic Neurosciences (GSN), Planegg-Martinsried, Germany
| | - Dorothee Dormann
- BioMedical Center (BMC), Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany.,Graduate School of Systemic Neurosciences (GSN), Planegg-Martinsried, Germany.,Munich Cluster for Systems Neurology (SyNergy), Germany
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33
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Synofzik M, Schüle R. Overcoming the divide between ataxias and spastic paraplegias: Shared phenotypes, genes, and pathways. Mov Disord 2017; 32:332-345. [PMID: 28195350 PMCID: PMC6287914 DOI: 10.1002/mds.26944] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 01/07/2017] [Accepted: 01/15/2017] [Indexed: 12/11/2022] Open
Abstract
Autosomal-dominant spinocerebellar ataxias, autosomal-recessive spinocerebellar ataxias, and hereditary spastic paraplegias have traditionally been designated in separate clinicogenetic disease classifications. This classification system still largely frames clinical thinking and genetic workup in clinical practice. Yet, with the advent of next-generation sequencing, phenotypically unbiased studies have revealed the limitations of this classification system. Various genes (eg, SPG7, SYNE1, PNPLA6) traditionally rooted in either the ataxia or hereditary spastic paraplegia classification system have now been shown to cause ataxia on the one end of the disease continuum and hereditary spastic paraplegia on the other. Other genes such as GBA2 and KIF1C were almost simultaneously published as both a hereditary spastic paraplegia and an ataxia gene. The variability and fluidity of observed phenotypes along the ataxia-spasticity spectrum warrants a rethinking of the traditional classification system. We propose to replace this divisive diagnosis-driven ataxia and hereditary spastic paraplegia classification system by a descriptive, unbiased approach of modular phenotyping. This approach is also open to expansion of the phenotype beyond ataxia and spasticity, which often occur as part of broader multisystem neuronal dysfunction. The concept of a continuous ataxia-spasticity disease spectrum is further supported by ataxias and hereditary spastic paraplegias sharing not only overlapping phenotypes and underlying genes, but also common cellular pathways and disease mechanisms. This suggests a shared vulnerability of cerebellar and corticospinal neurons for common pathophysiological processes. It might be this mechanistic overlap that drives their clinical overlap. A mechanistically inspired classification system will help to pave the way for mechanism-based strategies for drug development. © 2017 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Matthis Synofzik
- Department of Neurodegeneration, Hertie Institute for Clinical Brain Research (HIH), University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Rebecca Schüle
- Department of Neurodegeneration, Hertie Institute for Clinical Brain Research (HIH), University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
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34
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Majumder P, Chu JF, Chatterjee B, Swamy KBS, Shen CKJ. Co-regulation of mRNA translation by TDP-43 and Fragile X Syndrome protein FMRP. Acta Neuropathol 2016; 132:721-738. [PMID: 27518042 PMCID: PMC5073124 DOI: 10.1007/s00401-016-1603-8] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/28/2016] [Accepted: 07/28/2016] [Indexed: 01/15/2023]
Abstract
For proper mammalian brain development and functioning, the translation of many neuronal mRNAs needs to be repressed without neuronal activity stimulations. We have discovered that the expression of a subclass of neuronal proteins essential for neurodevelopment and neuron plasticity is co-regulated at the translational level by TDP-43 and the Fragile X Syndrome protein FMRP. Using molecular, cellular and imaging approaches, we show that these two RNA-binding proteins (RBP) co-repress the translation initiation of Rac1, Map1b and GluR1 mRNAs, and consequently the hippocampal spinogenesis. The co-repression occurs through binding of TDP-43 to mRNA(s) at specific UG/GU sequences and recruitment of the inhibitory CYFIP1-FMRP complex by its glycine-rich domain. This novel regulatory scenario could be utilized to silence a significant portion of around 160 common target mRNAs of the two RBPs. The study establishes a functional/physical partnership between FMRP and TDP-43 that mechanistically links several neurodevelopmental disorders and neurodegenerative diseases.
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35
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Mouzat K, Raoul C, Polge A, Kantar J, Camu W, Lumbroso S. Liver X receptors: from cholesterol regulation to neuroprotection-a new barrier against neurodegeneration in amyotrophic lateral sclerosis? Cell Mol Life Sci 2016; 73:3801-8. [PMID: 27510420 PMCID: PMC11108529 DOI: 10.1007/s00018-016-2330-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 08/04/2016] [Indexed: 12/13/2022]
Abstract
Cholesterol plays a central role in numerous nervous system functions. Cholesterol is the major constituent of myelin sheaths, is essential for synapse and dendrite formation, axon guidance as well as neurotransmission. Among regulators of cholesterol homeostasis, liver X receptors (LXRs), two members of the nuclear receptor superfamily, play a determinant role. LXRs act as cholesterol sensors and respond to high intracellular cholesterol concentration by decreasing plasmatic and intracellular cholesterol content. Beyond their cholesterol-lowering role, LXRs have been proposed as regulators of immunity and anti-inflammatory factors. Dysregulation of cholesterol metabolism combined to neuroinflammatory context have been described in neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). ALS is characterized by the progressive loss of motoneurons in the brain and spinal cord, leading to severe paralytic condition and death of patients in a median time of 3 years. Motoneuron degeneration is accompanied by chronic neuroinflammatory response, involving microglial and astrocytic activation, infiltration of blood-derived immune cells and release of pro-inflammatory factors. We propose to discuss here the role of LXRs as a molecular link between the central nervous system cholesterol metabolism, neuroinflammation, motoneuron survival and their potential as promising therapeutic candidates for ALS therapy.
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Affiliation(s)
- Kevin Mouzat
- Department of Biochemistry and Molecular Biology, Nîmes University Hospital, Nîmes, France.
- University of Montpellier, Montpellier, France.
- INSERM UMR1051, The Neuroscience Institute of Montpellier (INM), Saint Eloi Hospital, Montpellier, France.
| | - Cédric Raoul
- INSERM UMR1051, The Neuroscience Institute of Montpellier (INM), Saint Eloi Hospital, Montpellier, France
| | - Anne Polge
- Department of Biochemistry and Molecular Biology, Nîmes University Hospital, Nîmes, France
| | - Jovana Kantar
- Department of Biochemistry and Molecular Biology, Nîmes University Hospital, Nîmes, France
- INSERM UMR1051, The Neuroscience Institute of Montpellier (INM), Saint Eloi Hospital, Montpellier, France
| | - William Camu
- University of Montpellier, Montpellier, France
- INSERM UMR1051, The Neuroscience Institute of Montpellier (INM), Saint Eloi Hospital, Montpellier, France
- Neurology Department, ALS Center, Gui de Chauliac Hospital, Montpellier, France
| | - Serge Lumbroso
- Department of Biochemistry and Molecular Biology, Nîmes University Hospital, Nîmes, France
- University of Montpellier, Montpellier, France
- INSERM UMR1051, The Neuroscience Institute of Montpellier (INM), Saint Eloi Hospital, Montpellier, France
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36
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Rao M, Gershon MD. The bowel and beyond: the enteric nervous system in neurological disorders. Nat Rev Gastroenterol Hepatol 2016; 13:517-28. [PMID: 27435372 PMCID: PMC5005185 DOI: 10.1038/nrgastro.2016.107] [Citation(s) in RCA: 342] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The enteric nervous system (ENS) is large, complex and uniquely able to orchestrate gastrointestinal behaviour independently of the central nervous system (CNS). An intact ENS is essential for life and ENS dysfunction is often linked to digestive disorders. The part the ENS plays in neurological disorders, as a portal or participant, has also become increasingly evident. ENS structure and neurochemistry resemble that of the CNS, therefore pathogenic mechanisms that give rise to CNS disorders might also lead to ENS dysfunction, and nerves that interconnect the ENS and CNS can be conduits for disease spread. We review evidence for ENS dysfunction in the aetiopathogenesis of autism spectrum disorder, amyotrophic lateral sclerosis, transmissible spongiform encephalopathies, Parkinson disease and Alzheimer disease. Animal models suggest that common pathophysiological mechanisms account for the frequency of gastrointestinal comorbidity in these conditions. Moreover, the neurotropic pathogen, varicella zoster virus (VZV), unexpectedly establishes latency in enteric and other autonomic neurons that do not innervate skin. VZV reactivation in these neurons produces no rash and is therefore a clandestine cause of gastrointestinal disease, meningitis and strokes. The gut-brain alliance has raised consciousness as a contributor to health, but a gut-brain axis that contributes to disease merits equal attention.
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Affiliation(s)
- Meenakshi Rao
- Department of Pediatrics, Columbia University College of Physicians and Surgeons, 622 West 168th Street, New York, New York 10032, USA
| | - Michael D. Gershon
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, New York 10032, USA
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