101
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Molliex A, Temirov J, Lee J, Coughlin M, Kanagaraj AP, Kim HJ, Mittag T, Taylor JP. Phase separation by low complexity domains promotes stress granule assembly and drives pathological fibrillization. Cell 2015; 163:123-33. [PMID: 26406374 PMCID: PMC5149108 DOI: 10.1016/j.cell.2015.09.015] [Citation(s) in RCA: 1712] [Impact Index Per Article: 190.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/05/2015] [Accepted: 08/25/2015] [Indexed: 02/07/2023]
Abstract
Stress granules are membrane-less organelles composed of RNA-binding proteins (RBPs) and RNA. Functional impairment of stress granules has been implicated in amyotrophic lateral sclerosis, frontotemporal dementia, and multisystem proteinopathy-diseases that are characterized by fibrillar inclusions of RBPs. Genetic evidence suggests a link between persistent stress granules and the accumulation of pathological inclusions. Here, we demonstrate that the disease-related RBP hnRNPA1 undergoes liquid-liquid phase separation (LLPS) into protein-rich droplets mediated by a low complexity sequence domain (LCD). While the LCD of hnRNPA1 is sufficient to mediate LLPS, the RNA recognition motifs contribute to LLPS in the presence of RNA, giving rise to several mechanisms for regulating assembly. Importantly, while not required for LLPS, fibrillization is enhanced in protein-rich droplets. We suggest that LCD-mediated LLPS contributes to the assembly of stress granules and their liquid properties and provides a mechanistic link between persistent stress granules and fibrillar protein pathology in disease.
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Affiliation(s)
- Amandine Molliex
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jamshid Temirov
- Cell and Tissue Imaging Center, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jihun Lee
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Maura Coughlin
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Anderson P Kanagaraj
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Hong Joo Kim
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Tanja Mittag
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - J Paul Taylor
- Howard Hughes Medical Institute, Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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Shrestha A, Megeney LA. Yeast proteinopathy models: a robust tool for deciphering the basis of neurodegeneration. MICROBIAL CELL 2015; 2:458-465. [PMID: 28357271 PMCID: PMC5354604 DOI: 10.15698/mic2015.12.243] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein quality control or proteostasis is an essential determinant of basic cell health and aging. Eukaryotic cells have evolved a number of proteostatic mechanisms to ensure that proteins retain functional conformation, or are rapidly degraded when proteins misfold or self-aggregate. Disruption of proteostasis is now widely recognized as a key feature of aging related illness, specifically neurodegenerative disease. For example, Alzheimer’s disease, Huntington’s disease, Parkinson’s disease and Amyotrophic Lateral Sclerosis (ALS) each target and afflict distinct neuronal cell subtypes, yet this diverse array of human pathologies share the defining feature of aberrant protein aggregation within the affected cell population. Here, we review the use of budding yeast as a robust proxy to study the intersection between proteostasis and neurodegenerative disease. The humanized yeast model has proven to be an amenable platform to identify both, conserved proteostatic mechanisms across eukaryotic phyla and novel disease specific molecular dysfunction. Moreover, we discuss the intriguing concept that yeast specific proteins may be utilized as bona fide therapeutic agents, to correct proteostasis errors across various forms of neurodegeneration.
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Affiliation(s)
- Amit Shrestha
- Ottawa Hospital Research Institute, Regenerative Medicine Program, Sprott Centre for Stem Cell Research, The Ottawa Hospital, Ottawa, Ontario, Canada. ; Department of Cellular and Molecular Medicine University of Ottawa, Ottawa, Ontario, Canada
| | - Lynn A Megeney
- Ottawa Hospital Research Institute, Regenerative Medicine Program, Sprott Centre for Stem Cell Research, The Ottawa Hospital, Ottawa, Ontario, Canada. ; Department of Cellular and Molecular Medicine University of Ottawa, Ottawa, Ontario, Canada ; Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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103
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Freischmidt A, Schöpflin M, Feiler MS, Fleck AK, Ludolph AC, Weishaupt JH. Profilin 1 with the amyotrophic lateral sclerosis associated mutation T109M displays unaltered actin binding and does not affect the actin cytoskeleton. BMC Neurosci 2015; 16:77. [PMID: 26572741 PMCID: PMC4647582 DOI: 10.1186/s12868-015-0214-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 11/03/2015] [Indexed: 12/11/2022] Open
Abstract
Background The recent identification of several mutations in PFN1, a protein involved in actin dynamics, strengthens the hypothesis that pathology of amyotrophic lateral sclerosis is linked to cytoskeletal defects. Impaired actin binding is a common denominator of several PFN1 mutations associated with amyotrophic lateral sclerosis, although further mechanisms may also contribute to the death of motor neurons. In this study we examine the actin binding properties of PFN1 carrying the causal T109M mutation and its effects on the actin cytoskeleton. Methods Actin binding of PFN1 T109M was examined by co-immunoprecipitation experiments, a split luciferase complementation assay and a pulldown assay with recombinant PFN1. The actin cytoskeleton was investigated by fluorescence microscopy and by ultracentrifuge separation of globular and filamentous actin fractions followed by Western blotting. Results Using different technical approaches we show that PFN1 T109M displays unaltered actin binding. Furthermore we show that the actin cytoskeleton is not affected by PFN1 carrying the T109M mutation. Conclusion Our data suggest that actin independent mechanisms contribute to the pathogenicity of PFN1 T109M and possibly other PFN1 mutations.
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Affiliation(s)
- Axel Freischmidt
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
| | - Marcel Schöpflin
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
| | - Marisa S Feiler
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
| | - Ann-Katrin Fleck
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
| | - Albert C Ludolph
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
| | - Jochen H Weishaupt
- Department of Neurology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
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104
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Gallego-Iradi MC, Clare AM, Brown HH, Janus C, Lewis J, Borchelt DR. Subcellular Localization of Matrin 3 Containing Mutations Associated with ALS and Distal Myopathy. PLoS One 2015; 10:e0142144. [PMID: 26528920 PMCID: PMC4631352 DOI: 10.1371/journal.pone.0142144] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/18/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Mutations in Matrin 3 [MATR3], an RNA- and DNA-binding protein normally localized to the nucleus, have been linked to amyotrophic lateral sclerosis (ALS) and distal myopathies. In the present study, we have used transient transfection of cultured cell lines to examine the impact of different disease-causing mutations on the localization of Matrin 3 within cells. RESULTS Using CHO and human H4 neuroglioma cell models, we find that ALS/myopathy mutations do not produce profound changes in the localization of the protein. Although we did observe variable levels of Matrin 3 in the cytoplasm either by immunostaining or visualization of fluorescently-tagged protein, the majority of cells expressing either wild-type (WT) or mutant Matrin 3 showed nuclear localization of the protein. When cytoplasmic immunostaining, or fusion protein fluorescence, was seen in the cytoplasm, the stronger intensity of staining or fluorescence was usually evident in the nucleus. In ~80% of cells treated with sodium arsenite (Ars) to induce cytoplasmic stress granules, the nuclear localization of WT and F115C mutant Matrin 3 was not disturbed. Notably, over-expression of mutant Matrin 3 did not induce the formation of obvious large inclusion-like structures in either the cytoplasm or nucleus. CONCLUSIONS Our findings indicate that mutations in Matrin 3 that are associated with ALS and myopathy do not dramatically alter the normal localization of the protein or readily induce inclusion formation.
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Affiliation(s)
- M. Carolina Gallego-Iradi
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
- Santa Fe HealthCare Alzheimer’s Disease Research Center, University of Florida, Gainesville, Florida, United States of America
| | - Alexis M. Clare
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
| | - Hilda H. Brown
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
- Santa Fe HealthCare Alzheimer’s Disease Research Center, University of Florida, Gainesville, Florida, United States of America
| | - Christopher Janus
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
| | - Jada Lewis
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
| | - David R. Borchelt
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
- Santa Fe HealthCare Alzheimer’s Disease Research Center, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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Aulas A, Vande Velde C. Alterations in stress granule dynamics driven by TDP-43 and FUS: a link to pathological inclusions in ALS? Front Cell Neurosci 2015; 9:423. [PMID: 26557057 PMCID: PMC4615823 DOI: 10.3389/fncel.2015.00423] [Citation(s) in RCA: 160] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/06/2015] [Indexed: 12/12/2022] Open
Abstract
Stress granules (SGs) are RNA-containing cytoplasmic foci formed in response to stress exposure. Since their discovery in 1999, over 120 proteins have been described to be localized to these structures (in 154 publications). Most of these components are RNA binding proteins (RBPs) or are involved in RNA metabolism and translation. SGs have been linked to several pathologies including inflammatory diseases, cancer, viral infection, and neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). In ALS and FTD, the majority of cases have no known etiology and exposure to external stress is frequently proposed as a contributor to either disease initiation or the rate of disease progression. Of note, both ALS and FTD are characterized by pathological inclusions, where some well-known SG markers localize with the ALS related proteins TDP-43 and FUS. We propose that TDP-43 and FUS serve as an interface between genetic susceptibility and environmental stress exposure in disease pathogenesis. Here, we will discuss the role of TDP-43 and FUS in SG dynamics and how disease-linked mutations affect this process.
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Affiliation(s)
- Anaïs Aulas
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal Montréal, QC, Canada ; Department of Biochemistry, Université de Montréal Montréal, QC, Canada
| | - Christine Vande Velde
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal Montréal, QC, Canada ; Department of Neurosciences, Université de Montréal Montréal, QC, Canada
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106
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Brettle M, Suchowerska AK, Chua SW, Ittner LM, Fath T. Amyotrophic lateral sclerosis-associated mutant profilin 1 increases dendritic arborisation and spine formation in primary hippocampal neurons. Neurosci Lett 2015; 609:223-8. [PMID: 26499959 DOI: 10.1016/j.neulet.2015.09.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/25/2015] [Accepted: 09/26/2015] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease and familial ALS accounts for 10% of cases. The identification of familial ALS mutations in the actin-binding protein profilin 1 directly implicates actin dynamics and regulation in the pathogenesis of ALS. The mechanism by which these mutations cause ALS is unknown. In this study we show that expression of the ALS-associated actin-binding deficient mutant of PFN1 (PFN1(C71G)) results in increased dendritic arborisation and spine formation, and cytoplasmic inclusions in cultured mouse hippocampal neurons.
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Affiliation(s)
- Merryn Brettle
- Neurodegeneration and Repair Unit, School of Medical Sciences, University of New South Wales, Australia
| | - Alexandra K Suchowerska
- Neurodegeneration and Repair Unit, School of Medical Sciences, University of New South Wales, Australia
| | - Sook W Chua
- Dementia Research Unit, School of Medical Sciences, University of New South Wales, Australia
| | - Lars M Ittner
- Dementia Research Unit, School of Medical Sciences, University of New South Wales, Australia.
| | - Thomas Fath
- Neurodegeneration and Repair Unit, School of Medical Sciences, University of New South Wales, Australia.
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107
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Biasiotto G, Di Lorenzo D, Archetti S, Zanella I. Iron and Neurodegeneration: Is Ferritinophagy the Link? Mol Neurobiol 2015; 53:5542-74. [PMID: 26468157 DOI: 10.1007/s12035-015-9473-y] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/01/2015] [Indexed: 12/12/2022]
Abstract
Mounting evidence indicates that the lysosome-autophagy pathway plays a critical role in iron release from ferritin, the main iron storage cellular protein, hence in the distribution of iron to the cells. The recent identification of nuclear receptor co-activator 4 as the receptor for ferritin delivery to selective autophagy sheds further light on the understanding of the mechanisms underlying this pathway. The emerging view is that iron release from ferritin through the lysosomes is a general mechanism in normal and tumour cells of different tissue origins, but it has not yet been investigated in brain cells. Defects in the lysosome-autophagy pathway are often involved in the pathogenesis of neurodegenerative disorders, and brain iron homeostasis disruption is a hallmark of many of these diseases. However, in most cases, it has not been established whether iron dysregulation is directly involved in the pathogenesis of the diseases or if it is a secondary effect derived from other pathogenic mechanisms. The recent evidence of the crucial involvement of autophagy in cellular iron handling offers new perspectives about the role of iron in neurodegeneration, suggesting that autophagy dysregulation could cause iron dyshomeostasis. In this review, we recapitulate our current knowledge on the routes through which iron is released from ferritin, focusing on the most recent advances. We summarise the current evidence concerning lysosome-autophagy pathway dysfunctions and those of iron metabolism and discuss their potential interconnections in several neurodegenerative disorders, such as Alzheimer's, Parkinson's and Huntington's diseases; amyotrophic lateral sclerosis; and frontotemporal lobar dementia.
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Affiliation(s)
- Giorgio Biasiotto
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy
- Biotechnology Laboratory, Department of Diagnostics, Civic Hospital of Brescia, Piazzale Spedali Civili 1, 25123, Brescia, Italy
| | - Diego Di Lorenzo
- Biotechnology Laboratory, Department of Diagnostics, Civic Hospital of Brescia, Piazzale Spedali Civili 1, 25123, Brescia, Italy
| | - Silvana Archetti
- Biotechnology Laboratory, Department of Diagnostics, Civic Hospital of Brescia, Piazzale Spedali Civili 1, 25123, Brescia, Italy
| | - Isabella Zanella
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy.
- Biotechnology Laboratory, Department of Diagnostics, Civic Hospital of Brescia, Piazzale Spedali Civili 1, 25123, Brescia, Italy.
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108
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Abdelkarim S, Morgan S, Plagnol V, Lu CH, Adamson G, Howard R, Malaspina A, Orrell R, Sharma N, Sidle K, Clarke J, Fox NC, Rossor MN, Warren JD, Clark CN, Rohrer JD, Fisher EMC, Mead S, Pittman A, Fratta P. CHCHD10 Pro34Ser is not a highly penetrant pathogenic variant for amyotrophic lateral sclerosis and frontotemporal dementia. Brain 2015; 139:e9. [PMID: 26362910 DOI: 10.1093/brain/awv223] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Samir Abdelkarim
- 1 Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Sarah Morgan
- 2 Department of Molecular Neuroscience, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Vincent Plagnol
- 3 UCL Genetics Institute, Department of Genetics, Environment and Evolution, UCL, London WC1E 6BT, UK
| | - Ching-Hua Lu
- 4 Sobell Department of Motor Neuroscience and Movement Disorders, Queen Square, London, WC1N 3BG, UK 5 Centre for Neuroscience and Trauma, Blizard Institute, Queen Mary University of London, North-East London and Essex Regional MND Care Centre, E1 2AT, UK
| | - Gary Adamson
- 6 Medical Research Council Prion Unit, Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - Robin Howard
- 7 National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Andrea Malaspina
- 5 Centre for Neuroscience and Trauma, Blizard Institute, Queen Mary University of London, North-East London and Essex Regional MND Care Centre, E1 2AT, UK
| | - Richard Orrell
- 2 Department of Molecular Neuroscience, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Nikhil Sharma
- 4 Sobell Department of Motor Neuroscience and Movement Disorders, Queen Square, London, WC1N 3BG, UK
| | - Katie Sidle
- 2 Department of Molecular Neuroscience, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Jan Clarke
- 7 National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Nick C Fox
- 8 Dementia Research Centre, Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Martin N Rossor
- 8 Dementia Research Centre, Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Jason D Warren
- 8 Dementia Research Centre, Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Camilla N Clark
- 8 Dementia Research Centre, Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Jonathan D Rohrer
- 8 Dementia Research Centre, Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Elizabeth M C Fisher
- 1 Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Simon Mead
- 6 Medical Research Council Prion Unit, Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - Alan Pittman
- 2 Department of Molecular Neuroscience, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Pietro Fratta
- 1 Department of Neurodegenerative Disease, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK 4 Sobell Department of Motor Neuroscience and Movement Disorders, Queen Square, London, WC1N 3BG, UK
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Autophagy and Neurodegeneration: Insights from a Cultured Cell Model of ALS. Cells 2015; 4:354-86. [PMID: 26287246 PMCID: PMC4588041 DOI: 10.3390/cells4030354] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 07/07/2015] [Accepted: 07/27/2015] [Indexed: 12/11/2022] Open
Abstract
Autophagy plays a major role in the elimination of cellular waste components, the renewal of intracellular proteins and the prevention of the build-up of redundant or defective material. It is fundamental for the maintenance of homeostasis and especially important in post-mitotic neuronal cells, which, without competent autophagy, accumulate protein aggregates and degenerate. Many neurodegenerative diseases are associated with defective autophagy; however, whether altered protein turnover or accumulation of misfolded, aggregate-prone proteins is the primary insult in neurodegeneration has long been a matter of debate. Amyotrophic lateral sclerosis (ALS) is a fatal disease characterized by selective degeneration of motor neurons. Most of the ALS cases occur in sporadic forms (SALS), while 10%–15% of the cases have a positive familial history (FALS). The accumulation in the cell of misfolded/abnormal proteins is a hallmark of both SALS and FALS, and altered protein degradation due to autophagy dysregulation has been proposed to contribute to ALS pathogenesis. In this review, we focus on the main molecular features of autophagy to provide a framework for discussion of our recent findings about the role in disease pathogenesis of the ALS-linked form of the VAPB gene product, a mutant protein that drives the generation of unusual cytoplasmic inclusions.
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110
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Boopathy S, Silvas TV, Tischbein M, Jansen S, Shandilya SM, Zitzewitz JA, Landers JE, Goode BL, Schiffer CA, Bosco DA. Structural basis for mutation-induced destabilization of profilin 1 in ALS. Proc Natl Acad Sci U S A 2015; 112:7984-9. [PMID: 26056300 PMCID: PMC4491777 DOI: 10.1073/pnas.1424108112] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mutations in profilin 1 (PFN1) are associated with amyotrophic lateral sclerosis (ALS); however, the pathological mechanism of PFN1 in this fatal disease is unknown. We demonstrate that ALS-linked mutations severely destabilize the native conformation of PFN1 in vitro and cause accelerated turnover of the PFN1 protein in cells. This mutation-induced destabilization can account for the high propensity of ALS-linked variants to aggregate and also provides rationale for their reported loss-of-function phenotypes in cell-based assays. The source of this destabilization is illuminated by the X-ray crystal structures of several PFN1 proteins, revealing an expanded cavity near the protein core of the destabilized M114T variant. In contrast, the E117G mutation only modestly perturbs the structure and stability of PFN1, an observation that reconciles the occurrence of this mutation in the control population. These findings suggest that a destabilized form of PFN1 underlies PFN1-mediated ALS pathogenesis.
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Affiliation(s)
- Sivakumar Boopathy
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Tania V Silvas
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Maeve Tischbein
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Silvia Jansen
- Department of Biology, Brandeis University, Waltham, MA 02453
| | - Shivender M Shandilya
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Jill A Zitzewitz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605
| | - John E Landers
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Bruce L Goode
- Department of Biology, Brandeis University, Waltham, MA 02453
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Daryl A Bosco
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605; Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605;
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Kukharsky MS, Quintiero A, Matsumoto T, Matsukawa K, An H, Hashimoto T, Iwatsubo T, Buchman VL, Shelkovnikova TA. Calcium-responsive transactivator (CREST) protein shares a set of structural and functional traits with other proteins associated with amyotrophic lateral sclerosis. Mol Neurodegener 2015; 10:20. [PMID: 25888396 PMCID: PMC4428507 DOI: 10.1186/s13024-015-0014-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/25/2015] [Indexed: 12/14/2022] Open
Abstract
Background Mutations in calcium-responsive transactivator (CREST) encoding gene have been recently linked to ALS. Similar to several proteins implicated in ALS, CREST contains a prion-like domain and was reported to be a component of paraspeckles. Results We demonstrate that CREST is prone to aggregation and co-aggregates with FUS but not with other two ALS-linked proteins, TDP-43 and TAF15, in cultured cells. Aggregation of CREST affects paraspeckle integrity, probably by trapping other paraspeckle proteins within aggregates. Like several other ALS-associated proteins, CREST is recruited to induced stress granules. Neither of the CREST mutations described in ALS alters its subcellular localization, stress granule recruitment or detergent solubility; however Q388stop mutation results in elevated steady-state levels and more frequent nuclear aggregation of the protein. Both wild-type protein and its mutants negatively affect neurite network complexity of unstimulated cultured neurons when overexpressed, with Q388stop mutation being the most deleterious. When overexpressed in the fly eye, wild-type CREST or its mutants lead to severe retinal degeneration without obvious differences between the variants. Conclusions Our data indicate that CREST and certain other ALS-linked proteins share several features implicated in ALS pathogenesis, namely the ability to aggregate, be recruited to stress granules and alter paraspeckle integrity. A change in CREST levels in neurons which might occur under pathological conditions would have a profound negative effect on neuronal homeostasis. Electronic supplementary material The online version of this article (doi:10.1186/s13024-015-0014-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michail S Kukharsky
- School of Biosciences, Cardiff University, Museum Avenue, CF10 3AX, Cardiff, UK. .,Institute of Physiologically Active Compounds Russian Academy of Sciences, 1 Severniy proezd, Chernogolovka, 142432, Moscow Region, Russian Federation.
| | - Annamaria Quintiero
- School of Biosciences, Cardiff University, Museum Avenue, CF10 3AX, Cardiff, UK.
| | - Taisei Matsumoto
- Department of Neuropathology, The University of Tokyo, Tokyo, Japan.
| | - Koji Matsukawa
- Department of Neuropathology, The University of Tokyo, Tokyo, Japan.
| | - Haiyan An
- School of Biosciences, Cardiff University, Museum Avenue, CF10 3AX, Cardiff, UK.
| | | | - Takeshi Iwatsubo
- Department of Neuropathology, The University of Tokyo, Tokyo, Japan.
| | - Vladimir L Buchman
- School of Biosciences, Cardiff University, Museum Avenue, CF10 3AX, Cardiff, UK.
| | - Tatyana A Shelkovnikova
- School of Biosciences, Cardiff University, Museum Avenue, CF10 3AX, Cardiff, UK. .,Institute of Physiologically Active Compounds Russian Academy of Sciences, 1 Severniy proezd, Chernogolovka, 142432, Moscow Region, Russian Federation.
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112
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Abstract
The degeneration of motor neurons in amyotrophic lateral sclerosis (ALS) inevitably causes paralysis and death within a matter of years. Mounting genetic and functional evidence suggest that abnormalities in RNA processing and metabolism underlie motor neuron loss in sporadic and familial ALS. Abnormal localization and aggregation of essential RNA-binding proteins are fundamental pathological features of sporadic ALS, and mutations in genes encoding RNA processing enzymes cause familial disease. Also, expansion mutations occurring in the noncoding region of C9orf72-the most common cause of inherited ALS-result in nuclear RNA foci, underscoring the link between abnormal RNA metabolism and neurodegeneration in ALS. This review summarizes the current understanding of RNA dysfunction in ALS, and builds upon this knowledge base to identify converging mechanisms of neurodegeneration in ALS. Potential targets for therapy development are highlighted, with particular emphasis on early and conserved pathways that lead to motor neuron loss in ALS.
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Affiliation(s)
- Sami J Barmada
- Department of Neurology, University of Michigan, 109 Zina Pitcher Place, 5015 Biomedical Sciences Research Building, SSPC 2200, Ann Arbor, MI, 48109, USA,
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Autophagy receptor defects and ALS-FTLD. Mol Cell Neurosci 2015; 66:43-52. [PMID: 25683489 DOI: 10.1016/j.mcn.2015.01.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/16/2015] [Accepted: 01/27/2015] [Indexed: 12/11/2022] Open
Abstract
Various pathophysiological mechanisms have been implicated in the ALS-FTLD clinicopathological spectrum of neurodegenerative disorders. Here we focus on the role of autophagy, an intracellular catabolic pathway, in these conditions. Growing evidence suggests that the autophagic process can be disturbed in ALS-FTLD, including by genetic mutations affecting autophagy receptor proteins (ubiquilin-2, optineurin, SQSTM1/p62) and regulators (VCP). Such mutations may impair clearance of autophagy substrates with pathological consequences. Recent studies have also uncovered a direct connection between autophagy and RNA processing, supporting an integrated model connecting several ALS-FTLD associated gene products. This article is part of a Special Issue entitled 'Neuronal Protein'.
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Couthouis J, Raphael AR, Daneshjou R, Gitler AD. Targeted exon capture and sequencing in sporadic amyotrophic lateral sclerosis. PLoS Genet 2014; 10:e1004704. [PMID: 25299611 PMCID: PMC4191946 DOI: 10.1371/journal.pgen.1004704] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 08/25/2014] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease that results in progressive degeneration of motor neurons, ultimately leading to paralysis and death. Approximately 10% of ALS cases are familial, with the remaining 90% of cases being sporadic. Genetic studies in familial cases of ALS have been extremely informative in determining the causative mutations behind ALS, especially as the same mutations identified in familial ALS can also cause sporadic disease. However, the cause of ALS in approximately 30% of familial cases and in the majority of sporadic cases remains unknown. Sporadic ALS cases represent an underutilized resource for genetic information about ALS; therefore, we undertook a targeted sequencing approach of 169 known and candidate ALS disease genes in 242 sporadic ALS cases and 129 matched controls to try to identify novel variants linked to ALS. We found a significant enrichment in novel and rare variants in cases versus controls, indicating that we are likely identifying disease associated mutations. This study highlights the utility of next generation sequencing techniques combined with functional studies and rare variant analysis tools to provide insight into the genetic etiology of a heterogeneous sporadic disease. Amyotrophic lateral sclerosis (ALS), also known as Charcot disease or Lou Gehrig's disease, is one of the most common neuromuscular diseases worldwide. This disease is characterized by a progressive degeneration of motor neurons, leading to patient death within a few years after onset. Despite the fact that most ALS cases are sporadic, most of the ALS genetic studies have focused on familial forms, leading to the genetic determination of cause for 70% of cases of familial ALS but for only 10% of sporadic ALS cases. This, coupled with the dearth of families available for study, suggests that researchers should begin tapping into the relatively untouched reservoir of available sporadic samples to identify novel genetic causes of sporadic ALS. Here we take advantage of high-throughput target sequencing techniques to test four different hypotheses about the genetic causes of ALS in sporadic ALS and uncover new candidate genes and pathways implicated in ALS.
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Affiliation(s)
- Julien Couthouis
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Alya R. Raphael
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Roxana Daneshjou
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Aaron D. Gitler
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail:
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115
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Matus S, Bosco DA, Hetz C. Autophagy meets fused in sarcoma-positive stress granules. Neurobiol Aging 2014; 35:2832-2835. [PMID: 25444610 DOI: 10.1016/j.neurobiolaging.2014.08.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 08/18/2014] [Indexed: 01/11/2023]
Abstract
Mutations in fused in sarcoma and/or translocated in liposarcoma (FUS, TLS or FUS) are linked to familial cases of amyotrophic lateral sclerosis (ALS). Mutant FUS selectively accumulates into discrete cytosolic structures known as stress granules under various stress conditions. In addition, mutant FUS expression can alter the dynamics and morphology of stress granules. Although the link between mutant FUS and stress granules is well established, the mechanisms modulating stress granule formation and disassembly in the context of ALS are poorly understood. In this issue of Neurobiology of Aging, Ryu et al. uncover the impact of autophagy on the potential toxicity of mutant FUS-positive stress granules. The authors provide evidence indicating that enhanced autophagy activity reduces the number of stress granules, which in the case of cells containing mutant FUS-positive stress granules, is neuroprotective. Overall, this study identifies an intersection between the proteostasis network and alterations in RNA metabolism in ALS through the dynamic assembly and disassembly of stress granules.
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Affiliation(s)
- Soledad Matus
- Neurounion Biomedical Foundation, CENPAR, Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile.
| | - Daryl A Bosco
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA; Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Claudio Hetz
- Neurounion Biomedical Foundation, CENPAR, Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile.
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