51
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Ramesh N, Pandey UB. Autophagy Dysregulation in ALS: When Protein Aggregates Get Out of Hand. Front Mol Neurosci 2017; 10:263. [PMID: 28878620 PMCID: PMC5572252 DOI: 10.3389/fnmol.2017.00263] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/03/2017] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder that results from the loss of upper and lower motor neurons. One of the key pathological hallmarks in diseased neurons is the mislocalization of disease-associated proteins and the formation of cytoplasmic aggregates of these proteins and their interactors due to defective protein quality control. This apparent imbalance in the cellular protein homeostasis could be a crucial factor in causing motor neuron death in the later stages of the disease in patients. Autophagy is a major protein degradation pathway that is involved in the clearance of protein aggregates and damaged organelles. Abnormalities in autophagy have been observed in numerous neurodegenerative disorders, including ALS. In this review, we discuss the contribution of autophagy dysfunction in various in vitro and in vivo models of ALS. Furthermore, we examine the crosstalk between autophagy and other cellular stresses implicated in ALS pathogenesis and the therapeutic implications of regulating autophagy in ALS.
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Affiliation(s)
- Nandini Ramesh
- Department of Human Genetics, University of Pittsburgh Graduate School of Public HealthPittsburgh, PA, United States.,Division of Child Neurology, Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical CenterPittsburgh, PA, United States
| | - Udai Bhan Pandey
- Department of Human Genetics, University of Pittsburgh Graduate School of Public HealthPittsburgh, PA, United States.,Division of Child Neurology, Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical CenterPittsburgh, PA, United States.,Department of Neurology, University of Pittsburgh School of MedicinePittsburgh, PA, United States
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52
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Haidar M, Timmerman V. Autophagy as an Emerging Common Pathomechanism in Inherited Peripheral Neuropathies. Front Mol Neurosci 2017; 10:143. [PMID: 28553203 PMCID: PMC5425483 DOI: 10.3389/fnmol.2017.00143] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 04/26/2017] [Indexed: 12/16/2022] Open
Abstract
The inherited peripheral neuropathies (IPNs) comprise a growing list of genetically heterogeneous diseases. With mutations in more than 80 genes being reported to cause IPNs, a wide spectrum of functional consequences is expected to follow this genotypic diversity. Hence, the search for a common pathomechanism among the different phenotypes has become the holy grail of functional research into IPNs. During the last decade, studies on several affected genes have shown a direct and/or indirect correlation with autophagy. Autophagy, a cellular homeostatic process, is required for the removal of cell aggregates, long-lived proteins and dead organelles from the cell in double-membraned vesicles destined for the lysosomes. As an evolutionarily highly conserved process, autophagy is essential for the survival and proper functioning of the cell. Recently, neuronal cells have been shown to be particularly vulnerable to disruption of the autophagic pathway. Furthermore, autophagy has been shown to be affected in various common neurodegenerative diseases of both the central and the peripheral nervous system including Alzheimer's, Parkinson's, and Huntington's diseases. In this review we provide an overview of the genes involved in hereditary neuropathies which are linked to autophagy and we propose the disruption of the autophagic flux as an emerging common pathomechanism. We also shed light on the different steps of the autophagy pathway linked to these genes. Finally, we review the concept of autophagy being a therapeutic target in IPNs, and the possibilities and challenges of this pathway-specific targeting.
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Affiliation(s)
- Mansour Haidar
- Peripheral Neuropathy Research Group, Institute Born Bunge, University of AntwerpAntwerpen, Belgium
| | - Vincent Timmerman
- Peripheral Neuropathy Research Group, Institute Born Bunge, University of AntwerpAntwerpen, Belgium
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53
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Webster CP, Smith EF, Shaw PJ, De Vos KJ. Protein Homeostasis in Amyotrophic Lateral Sclerosis: Therapeutic Opportunities? Front Mol Neurosci 2017; 10:123. [PMID: 28512398 PMCID: PMC5411428 DOI: 10.3389/fnmol.2017.00123] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 04/11/2017] [Indexed: 12/11/2022] Open
Abstract
Protein homeostasis (proteostasis), the correct balance between production and degradation of proteins, is essential for the health and survival of cells. Proteostasis requires an intricate network of protein quality control pathways (the proteostasis network) that work to prevent protein aggregation and maintain proteome health throughout the lifespan of the cell. Collapse of proteostasis has been implicated in the etiology of a number of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), the most common adult onset motor neuron disorder. Here, we review the evidence linking dysfunctional proteostasis to the etiology of ALS and discuss how ALS-associated insults affect the proteostasis network. Finally, we discuss the potential therapeutic benefit of proteostasis network modulation in ALS.
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Affiliation(s)
- Christopher P Webster
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - Emma F Smith
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - Pamela J Shaw
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
| | - Kurt J De Vos
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of SheffieldSheffield, UK
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54
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Kononenko NL, Claßen GA, Kuijpers M, Puchkov D, Maritzen T, Tempes A, Malik AR, Skalecka A, Bera S, Jaworski J, Haucke V. Retrograde transport of TrkB-containing autophagosomes via the adaptor AP-2 mediates neuronal complexity and prevents neurodegeneration. Nat Commun 2017; 8:14819. [PMID: 28387218 PMCID: PMC5385568 DOI: 10.1038/ncomms14819] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 02/06/2017] [Indexed: 12/29/2022] Open
Abstract
Autophagosomes primarily mediate turnover of cytoplasmic proteins or organelles to provide nutrients and eliminate damaged proteins. In neurons, autophagosomes form in distal axons and are trafficked retrogradely to fuse with lysosomes in the soma. Although defective neuronal autophagy is associated with neurodegeneration, the function of neuronal autophagosomes remains incompletely understood. We show that in neurons, autophagosomes promote neuronal complexity and prevent neurodegeneration in vivo via retrograde transport of brain-derived neurotrophic factor (BDNF)-activated TrkB receptors. p150Glued/dynactin-dependent transport of TrkB-containing autophagosomes requires their association with the endocytic adaptor AP-2, an essential protein complex previously thought to function exclusively in clathrin-mediated endocytosis. These data highlight a novel non-canonical function of AP-2 in retrograde transport of BDNF/TrkB-containing autophagosomes in neurons and reveal a causative link between autophagy and BDNF/TrkB signalling. The endocytic adaptor protein complex AP-2 is mostly known for its role in endocytosis and in synaptic vesicle reformation. Here the authors show that AP-2 also mediates retrograde transport of TrkB-containing autophagosomes in neurons; this process promotes neuronal complexity and prevents the degeneration of cortical and thalamic neurons.
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Affiliation(s)
- Natalia L Kononenko
- Leibniz-Institut für Molekulare Pharmakologie, 13125 Berlin, Germany.,NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, 10117 Berlin, Germany.,CECAD Research Center, University of Cologne, 50931 Cologne, Germany
| | - Gala A Claßen
- Leibniz-Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Marijn Kuijpers
- Leibniz-Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Dmytro Puchkov
- Leibniz-Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Tanja Maritzen
- Leibniz-Institut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Aleksandra Tempes
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Anna R Malik
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Agnieszka Skalecka
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Sujoy Bera
- CECAD Research Center, University of Cologne, 50931 Cologne, Germany
| | - Jacek Jaworski
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Volker Haucke
- Leibniz-Institut für Molekulare Pharmakologie, 13125 Berlin, Germany.,NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, 10117 Berlin, Germany.,Freie Universität Berlin, Faculty of Biology, Chemistry and Pharmacy, 14195 Berlin, Germany
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55
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Klemann CJHM, Visser JE, Van Den Bosch L, Martens GJM, Poelmans G. Integrated molecular landscape of amyotrophic lateral sclerosis provides insights into disease etiology. Brain Pathol 2017; 28:203-211. [PMID: 28035716 DOI: 10.1111/bpa.12485] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 12/23/2016] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a severe, progressive and ultimately fatal motor neuron disease caused by a combination of genetic and environmental factors, but its underlying mechanisms are largely unknown. To gain insight into the etiology of ALS, we here conducted genetic network and literature analyses of the top-ranked findings from six genome-wide association studies of sporadic ALS (involving 3589 cases and 8577 controls) as well as genes implicated in ALS etiology through other evidence, including familial ALS candidate gene association studies. We integrated these findings into a molecular landscape of ALS that allowed the identification of three main processes that interact with each other and are crucial to maintain axonal functionality, especially of the long axons of motor neurons, i.e. (1) Rho-GTPase signaling; (2) signaling involving the three regulatory molecules estradiol, folate, and methionine; and (3) ribonucleoprotein granule functioning and axonal transport. Interestingly, estradiol signaling is functionally involved in all three cascades and as such an important mediator of the molecular ALS landscape. Furthermore, epidemiological findings together with an analysis of possible gender effects in our own cohort of sporadic ALS patients indicated that estradiol may be a protective factor, especially for bulbar-onset ALS. Taken together, our molecular landscape of ALS suggests that abnormalities within three interconnected molecular processes involved in the functioning and maintenance of motor neuron axons are important in the etiology of ALS. Moreover, estradiol appears to be an important modulator of the ALS landscape, providing important clues for the development of novel disease-modifying treatments.
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Affiliation(s)
- C J H M Klemann
- Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition and Behaviour, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud University, Nijmegen, The Netherlands
| | - J E Visser
- Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition and Behaviour, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud University, Nijmegen, The Netherlands.,Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Neurology, Amphia Hospital, Breda, The Netherlands
| | - L Van Den Bosch
- Department of Neurosciences, Laboratory of Neurobiology, Experimental Neurology, KU Leuven and VIB, Vesalius Research Center, Leuven, Belgium
| | - G J M Martens
- Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition and Behaviour, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud University, Nijmegen, The Netherlands
| | - G Poelmans
- Department of Molecular Animal Physiology, Donders Institute for Brain, Cognition and Behaviour, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud University, Nijmegen, The Netherlands.,Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
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56
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Neisch AL, Neufeld TP, Hays TS. A STRIPAK complex mediates axonal transport of autophagosomes and dense core vesicles through PP2A regulation. J Cell Biol 2017; 216:441-461. [PMID: 28100687 PMCID: PMC5294782 DOI: 10.1083/jcb.201606082] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 11/09/2016] [Accepted: 12/27/2016] [Indexed: 02/06/2023] Open
Abstract
Autophagy plays an essential role in the cellular homeostasis of neurons, facilitating the clearance of cellular debris. This clearance process is orchestrated through the assembly, transport, and fusion of autophagosomes with lysosomes for degradation. The motor protein dynein drives autophagosome motility from distal sites of assembly to sites of lysosomal fusion. In this study, we identify the scaffold protein CKA (connector of kinase to AP-1) as essential for autophagosome transport in neurons. Together with other core components of the striatin-interacting phosphatase and kinase (STRIPAK) complex, we show that CKA associates with dynein and directly binds Atg8a, an autophagosomal protein. CKA is a regulatory subunit of PP2A, a component of the STRIPAK complex. We propose that the STRIPAK complex modulates dynein activity. Consistent with this hypothesis, we provide evidence that CKA facilitates axonal transport of dense core vesicles and autophagosomes in a PP2A-dependent fashion. In addition, CKA-deficient flies exhibit PP2A-dependent motor coordination defects. CKA function within the STRIPAK complex is crucial to prevent transport defects that may contribute to neurodegeneration.
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Affiliation(s)
- Amanda L Neisch
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455
| | - Thomas P Neufeld
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455
| | - Thomas S Hays
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455
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57
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Kim DK, Kim TH, Lee SJ. Mechanisms of aging-related proteinopathies in Caenorhabditis elegans. Exp Mol Med 2016; 48:e263. [PMID: 27713398 PMCID: PMC5099420 DOI: 10.1038/emm.2016.109] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/05/2016] [Accepted: 07/12/2016] [Indexed: 12/24/2022] Open
Abstract
Aging is the most important risk factor for human neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Pathologically, these diseases are characterized by the deposition of specific protein aggregates in neurons and glia, representing the impairment of neuronal proteostasis. However, the mechanism by which aging affects the proteostasis system and promotes protein aggregation remains largely unknown. The short lifespan and ample genetic resources of Caenorhabditis elegans (C. elegans) have made this species a favorite model organism for aging research, and the development of proteinopathy models in this organism has helped us to understand how aging processes affect protein aggregation and neurodegeneration. Here, we review the recent literature on proteinopathies in C. elegans models and discuss the insights we have gained into the mechanisms of how aging processes are integrated into the pathogenesis of various neurodegenerative diseases.
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Affiliation(s)
- Dong-Kyu Kim
- Department of Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea
- Department of Biomedical Science and Technology, Konkuk University, Seoul, Korea
| | - Tae Ho Kim
- Department of Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea
- Department of Medicine, Inha University School of Medicine, Incheon, Korea
| | - Seung-Jae Lee
- Department of Biomedical Sciences, Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Korea
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58
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Wijdeven RH, Janssen H, Nahidiazar L, Janssen L, Jalink K, Berlin I, Neefjes J. Cholesterol and ORP1L-mediated ER contact sites control autophagosome transport and fusion with the endocytic pathway. Nat Commun 2016; 7:11808. [PMID: 27283760 PMCID: PMC4906411 DOI: 10.1038/ncomms11808] [Citation(s) in RCA: 154] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 05/03/2016] [Indexed: 02/06/2023] Open
Abstract
Autophagy is the main homeostatic pathway guiding cytosolic materials for degradation by the lysosome. Maturation of autophagosomes requires their transport towards the perinuclear region of the cell, with key factors underlying both processes still poorly understood. Here we show that transport and positioning of late autophagosomes depends on cholesterol by way of the cholesterol-sensing Rab7 effector ORP1L. ORP1L localizes to late autophagosomes and—under low-cholesterol conditions—contacts the ER protein VAP-A, forming ER-autophagosome contact sites, which prevent minus-end transport by the Rab7–RILP–dynein complex. ORP1L-mediated contact sites also inhibit localization of PLEKHM1 to Rab7. PLEKHM1, together with RILP, then recruits the homotypic fusion and vacuole protein-sorting (HOPS) complex for fusion of autophagosomes with late endosomes and lysosomes. Thus, ORP1L, via its liganding by lipids and the formation of contacts between autophagic vacuoles and the ER, governs the last steps in autophagy that lead to the lysosomal degradation of cytosolic material. Autophagy requires transport of autophagosomes to the perinuclear region. Here, the authors show that ORP1L localizes to autophagosomes and mediates formation of ER contact sites that prevent autophagosome transport and fusion with endocytic vesicles when cholesterol levels are low.
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Affiliation(s)
- Ruud H Wijdeven
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Hans Janssen
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Leila Nahidiazar
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Lennert Janssen
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.,Department of Chemical Immunology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Kees Jalink
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Ilana Berlin
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.,Department of Chemical Immunology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
| | - Jacques Neefjes
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.,Department of Chemical Immunology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
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59
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Abstract
Autophagy is an essential homeostatic process for degrading cellular cargo. Aging organelles and protein aggregates are degraded by the autophagosome-lysosome pathway, which is particularly crucial in neurons. There is increasing evidence implicating defective autophagy in neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease, Parkinson's disease and Huntington's disease. Recent work using live-cell imaging has identified autophagy as a predominantly polarized process in neuronal axons; autophagosomes preferentially form at the axon tip and undergo retrograde transport back towards the cell body. Autophagosomes engulf cargo including damaged mitochondria (mitophagy) and protein aggregates, and subsequently fuse with lysosomes during axonal transport to effectively degrade their internalized cargo. In this Cell Science at a Glance article and the accompanying poster, we review recent progress on the dynamics of the autophagy pathway in neurons and highlight the defects observed at each step of this pathway during neurodegeneration.
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Affiliation(s)
- Yvette C Wong
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104 USA
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104 USA
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60
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Gershoni-Emek N, Mazza A, Chein M, Gradus-Pery T, Xiang X, Li KW, Sharan R, Perlson E. Proteomic Analysis of Dynein-Interacting Proteins in Amyotrophic Lateral Sclerosis Synaptosomes Reveals Alterations in the RNA-Binding Protein Staufen1. Mol Cell Proteomics 2015; 15:506-22. [PMID: 26598648 DOI: 10.1074/mcp.m115.049965] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Indexed: 12/12/2022] Open
Abstract
Synapse disruption takes place in many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). However, the mechanistic understanding of this process is still limited. We set out to study a possible role for dynein in synapse integrity. Cytoplasmic dynein is a multisubunit intracellular molecule responsible for diverse cellular functions, including long-distance transport of vesicles, organelles, and signaling factors toward the cell center. A less well-characterized role dynein may play is the spatial clustering and anchoring of various factors including mRNAs in distinct cellular domains such as the neuronal synapse. Here, in order to gain insight into dynein functions in synapse integrity and disruption, we performed a screen for novel dynein interactors at the synapse. Dynein immunoprecipitation from synaptic fractions of the ALS model mSOD1(G93A) and wild-type controls, followed by mass spectrometry analysis on synaptic fractions of the ALS model mSOD1(G93A) and wild-type controls, was performed. Using advanced network analysis, we identified Staufen1, an RNA-binding protein required for the transport and localization of neuronal RNAs, as a major mediator of dynein interactions via its interaction with protein phosphatase 1-beta (PP1B). Both in vitro and in vivo validation assays demonstrate the interactions of Staufen1 and PP1B with dynein, and their colocalization with synaptic markers was altered as a result of two separate ALS-linked mutations: mSOD1(G93A) and TDP43(A315T). Taken together, we suggest a model in which dynein's interaction with Staufen1 regulates mRNA localization along the axon and the synapses, and alterations in this process may correlate with synapse disruption and ALS toxicity.
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Affiliation(s)
- Noga Gershoni-Emek
- From the ‡Sagol School of Neuroscience and Department of Physiology and Pharmacology, Sackler School of Medicine and
| | - Arnon Mazza
- §Blavatnik School of Computer Science, Tel Aviv University, Israel
| | - Michael Chein
- From the ‡Sagol School of Neuroscience and Department of Physiology and Pharmacology, Sackler School of Medicine and
| | - Tal Gradus-Pery
- From the ‡Sagol School of Neuroscience and Department of Physiology and Pharmacology, Sackler School of Medicine and
| | - Xin Xiang
- ¶Department of Biochemistry and Molecular Biology, the Uniformed Services University of Health Sciences, Bethesda, MD
| | - Ka Wan Li
- ‖Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, the Netherlands
| | - Roded Sharan
- §Blavatnik School of Computer Science, Tel Aviv University, Israel
| | - Eran Perlson
- From the ‡Sagol School of Neuroscience and Department of Physiology and Pharmacology, Sackler School of Medicine and
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61
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Kaus A, Sareen D. ALS Patient Stem Cells for Unveiling Disease Signatures of Motoneuron Susceptibility: Perspectives on the Deadly Mitochondria, ER Stress and Calcium Triad. Front Cell Neurosci 2015; 9:448. [PMID: 26635528 PMCID: PMC4652136 DOI: 10.3389/fncel.2015.00448] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 11/02/2015] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a largely sporadic progressive neurodegenerative disease affecting upper and lower motoneurons (MNs) whose specific etiology is incompletely understood. Mutations in superoxide dismutase-1 (SOD1), TAR DNA-binding protein 43 (TARDBP/TDP-43) and C9orf72, have been identified in subsets of familial and sporadic patients. Key associated molecular and neuropathological features include ubiquitinated TDP-43 inclusions, stress granules, aggregated dipeptide proteins from mutant C9orf72 transcripts, altered mitochondrial ultrastructure, dysregulated calcium homeostasis, oxidative and endoplasmic reticulum (ER) stress, and an unfolded protein response (UPR). Such impairments have been documented in ALS animal models; however, whether these mechanisms are initiating factors or later consequential events leading to MN vulnerability in ALS patients is debatable. Human induced pluripotent stem cells (iPSCs) are a valuable tool that could resolve this “chicken or egg” causality dilemma. Relevant systems for probing pathophysiologically affected cells from large numbers of ALS patients and discovering phenotypic disease signatures of early MN susceptibility are described. Performing unbiased ‘OMICS and high-throughput screening in relevant neural cells from a cohort of ALS patient iPSCs, and rescuing mitochondrial and ER stress impairments, can identify targeted therapeutics for increasing MN longevity in ALS.
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Affiliation(s)
- Anjoscha Kaus
- Board of Governors-Regenerative Medicine Institute, Cedars-Sinai Medical Center Los Angeles, CA, USA ; Department of Biomedical Sciences, Cedars-Sinai Medical Center Los Angeles, CA, USA
| | - Dhruv Sareen
- Board of Governors-Regenerative Medicine Institute, Cedars-Sinai Medical Center Los Angeles, CA, USA ; Department of Biomedical Sciences, Cedars-Sinai Medical Center Los Angeles, CA, USA ; iPSC Core, The David and Janet Polak Stem Cell Laboratory, Cedars-Sinai Medical Center Los Angeles, CA, USA
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62
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Natale G, Lenzi P, Lazzeri G, Falleni A, Biagioni F, Ryskalin L, Fornai F. Compartment-dependent mitochondrial alterations in experimental ALS, the effects of mitophagy and mitochondriogenesis. Front Cell Neurosci 2015; 9:434. [PMID: 26594150 PMCID: PMC4635226 DOI: 10.3389/fncel.2015.00434] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 10/15/2015] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is characterized by massive loss of motor neurons. Data from ALS patients and experimental models indicate that mitochondria are severely damaged within dying or spared motor neurons. Nonetheless, recent data indicate that mitochondrial preservation, although preventing motor neuron loss, fails to prolong lifespan. On the other hand, the damage to motor axons plays a pivotal role in determining both lethality and disease course. Thus, in the present article each motor neuron compartment (cell body, central, and peripheral axons) of G93A SOD-1 mice was studied concerning mitochondrial alterations as well as other intracellular structures. We could confirm the occurrence of ALS-related mitochondrial damage encompassing total swelling, matrix dilution and cristae derangement along with non-pathological variations of mitochondrial size and number. However, these alterations occur to a different extent depending on motor neuron compartment. Lithium, a well-known autophagy inducer, prevents most pathological changes. However, the efficacy of lithium varies depending on which motor neuron compartment is considered. Remarkably, some effects of lithium are also evident in wild type mice. Lithium is effective also in vitro, both in cell lines and primary cell cultures from the ventral spinal cord. In these latter cells autophagy inhibition within motor neurons in vitro reproduced ALS pathology which was reversed by lithium. Muscle and glial cells were analyzed as well. Cell pathology was mostly severe within peripheral axons and muscles of ALS mice. Remarkably, when analyzing motor axons of ALS mice a subtotal clogging of axoplasm was described for the first time, which was modified under the effects of lithium. The effects induced by lithium depend on several mechanisms such as direct mitochondrial protection, induction of mitophagy and mitochondriogenesis. In this study, mitochondriogenesis induced by lithium was confirmed in situ by a novel approach using [2-3H]-adenosine.
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Affiliation(s)
- Gianfranco Natale
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Italy
| | - Paola Lenzi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Italy
| | - Gloria Lazzeri
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Italy
| | - Alessandra Falleni
- Department of Clinical and Experimental Medicine, University of Pisa Italy
| | | | - Larisa Ryskalin
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Italy
| | - Francesco Fornai
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Italy ; I.R.C.C.S., Neuromed Pozzilli, Italy
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63
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Rint1 inactivation triggers genomic instability, ER stress and autophagy inhibition in the brain. Cell Death Differ 2015; 23:454-68. [PMID: 26383973 DOI: 10.1038/cdd.2015.113] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 06/30/2015] [Accepted: 07/08/2015] [Indexed: 11/08/2022] Open
Abstract
Endoplasmic reticulum (ER) stress, defective autophagy and genomic instability in the central nervous system are often associated with severe developmental defects and neurodegeneration. Here, we reveal the role played by Rint1 in these different biological pathways to ensure normal development of the central nervous system and to prevent neurodegeneration. We found that inactivation of Rint1 in neuroprogenitors led to death at birth. Depletion of Rint1 caused genomic instability due to chromosome fusion in dividing cells. Furthermore, Rint1 deletion in developing brain promotes the disruption of ER and Cis/Trans Golgi homeostasis in neurons, followed by ER-stress increase. Interestingly, Rint1 deficiency was also associated with the inhibition of the autophagosome clearance. Altogether, our findings highlight the crucial roles of Rint1 in vivo in genomic stability maintenance, as well as in prevention of ER stress and autophagy.
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Ruffoli R, Bartalucci A, Frati A, Fornai F. Ultrastructural studies of ALS mitochondria connect altered function and permeability with defects of mitophagy and mitochondriogenesis. Front Cell Neurosci 2015; 9:341. [PMID: 26388731 PMCID: PMC4555074 DOI: 10.3389/fncel.2015.00341] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 08/17/2015] [Indexed: 12/11/2022] Open
Abstract
The key role of mitochondria in patients affected by amyotrophic lateral sclerosis (ALS) is well documented by electron microscopy studies of motor neurons within spinal cord and brainstem. Nonetheless, recent studies challenged the role of mitochondria placed within the cell body of motor neuron. In fact, it was demonstrated that, despite preservation of mitochondria placed within this compartment, there is no increase in the lifespan of transgenic mouse models of ALS. Thus, the present mini-review comments on morphological findings of mitochondrial alterations in ALS patients in connection with novel findings about mitochondrial dynamics within various compartments of motor neurons. The latter issue was recently investigated in relationship with altered calcium homeostasis and autophagy, which affect mitochondria in ALS. In fact, it was recently indicated that a pathological mitophagy, mitochondriogenesis and calcium homeostasis produce different ultrastructural effects within specific regions of motor neurons. This might explain why specific compartments of motor neurons possess different thresholds to mitochondrial damage. In particular, it appears that motor axons represent the most sensitive compartment which undergoes the earliest and most severe alterations in the course of ALS. It is now evident that altered calcium buffering is compartment-dependent, as well as mitophagy and mitochondriogenesis. On the other hand, mitochondrial homeostasis strongly relies on calcium handling, the removal of altered mitochondria through the autophagy flux (mitophagy) and the biogenesis of novel mitochondria (mitochondriogenesis). Thus, recent findings related to altered calcium storage and impaired autophagy flux in ALS may help to understand the occurrence of mitochondrial alterations as a hallmark in ALS patients. At the same time, the compartmentalization of such dysfunctions may be explained considering the compartments of calcium dynamics and autophagy flux within motor neurons.
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Affiliation(s)
- Riccardo Ruffoli
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy
| | - Alessia Bartalucci
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy
| | | | - Francesco Fornai
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy ; I.R.C.C.S., Neuromed Pozzilli, Italy
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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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Degradation of misfolded proteins in neurodegenerative diseases: therapeutic targets and strategies. Exp Mol Med 2015; 47:e147. [PMID: 25766616 PMCID: PMC4351408 DOI: 10.1038/emm.2014.117] [Citation(s) in RCA: 554] [Impact Index Per Article: 61.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 11/19/2014] [Indexed: 12/13/2022] Open
Abstract
Mammalian cells remove misfolded proteins using various proteolytic systems, including the ubiquitin (Ub)-proteasome system (UPS), chaperone mediated autophagy (CMA) and macroautophagy. The majority of misfolded proteins are degraded by the UPS, in which Ub-conjugated substrates are deubiquitinated, unfolded and cleaved into small peptides when passing through the narrow chamber of the proteasome. The substrates that expose a specific degradation signal, the KFERQ sequence motif, can be delivered to and degraded in lysosomes via the CMA. Aggregation-prone substrates resistant to both the UPS and the CMA can be degraded by macroautophagy, in which cargoes are segregated into autophagosomes before degradation by lysosomal hydrolases. Although most misfolded and aggregated proteins in the human proteome can be degraded by cellular protein quality control, some native and mutant proteins prone to aggregation into β-sheet-enriched oligomers are resistant to all known proteolytic pathways and can thus grow into inclusion bodies or extracellular plaques. The accumulation of protease-resistant misfolded and aggregated proteins is a common mechanism underlying protein misfolding disorders, including neurodegenerative diseases such as Huntington's disease (HD), Alzheimer's disease (AD), Parkinson's disease (PD), prion diseases and Amyotrophic Lateral Sclerosis (ALS). In this review, we provide an overview of the proteolytic pathways in neurons, with an emphasis on the UPS, CMA and macroautophagy, and discuss the role of protein quality control in the degradation of pathogenic proteins in neurodegenerative diseases. Additionally, we examine existing putative therapeutic strategies to efficiently remove cytotoxic proteins from degenerating neurons.
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Fan Y, Zhao HC, Liu J, Tan T, Ding T, Li R, Zhao Y, Yan J, Sun X, Yu Y, Qiao J. Aberrant expression of maternal Plk1 and Dctn3 results in the developmental failure of human in-vivo- and in-vitro-matured oocytes. Sci Rep 2015; 5:8192. [PMID: 25645239 PMCID: PMC4314639 DOI: 10.1038/srep08192] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 01/12/2015] [Indexed: 12/31/2022] Open
Abstract
Fertilisation is the first step in embryonic development, and dynamic changes of key genes may potentially improve assisted reproduction techniques efficiency during this process. Here, we analysed genes that were differentially expressed between oocytes and zygotes and focused on cytokinesis-related genes. Plk1 and Dctn3 were identified as showing dramatic changes in expression during fertilisation and were suggested to play a key role in inducing aneuploidy in zygotes and 8-cell embryos. Moreover, we found that maternal Plk1 and Dctn3 were expressed at lower levels in in vitro matured oocytes, which may have contributed to the high ratio of resulting embryos with abnormal Plk1 and Dctn3 expression levels, thereby reducing the developmental competence of the resulting embryos. Furthermore, the overexpression of Dctn3 can silence Plk1 expression, which suggests a potential regulation mechanism. In conclusion, our present study showed that aberrant expression of Plk1 and Dctn3 increases embryo aneuploidy and developmental failure, particularly in in vitro matured oocytes. Our results facilitate a better understanding of the effects of oocyte maternal gene expression on embryonic development and can be used to improve the outcome of assisted reproduction techniques.
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Affiliation(s)
- Yong Fan
- Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Hong-Cui Zhao
- Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, 100191, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, 100191, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, 100191, China
| | - Jianqiao Liu
- Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Tao Tan
- Yunnan Key Laboratory of Primate Biomedical Research and Kunming Biomed International and National Engineering Research Center of Biomedicine and Animal Science, Kunming, 650500, China
| | - Ting Ding
- Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, 100191, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, 100191, China
| | - Rong Li
- Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, 100191, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, 100191, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, 100191, China
| | - Yue Zhao
- Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, 100191, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, 100191, China
| | - Jie Yan
- Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, 100191, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, 100191, China
| | - Xiaofang Sun
- Key Laboratory for Major Obstetric Diseases of Guangdong Province, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Yang Yu
- Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, 100191, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, 100191, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, 100191, China
| | - Jie Qiao
- Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, 100191, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, 100191, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, 100191, China
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Xiao Y, Ma C, Yi J, Wu S, Luo G, Xu X, Lin PH, Sun J, Zhou J. Suppressed autophagy flux in skeletal muscle of an amyotrophic lateral sclerosis mouse model during disease progression. Physiol Rep 2015; 3:3/1/e12271. [PMID: 25602021 PMCID: PMC4387765 DOI: 10.14814/phy2.12271] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Accumulation of abnormal protein inclusions is implicated in motor neuron degeneration in amyotrophic lateral sclerosis (ALS). Autophagy, an intracellular process targeting misfolded proteins and damaged organelles for lysosomal degradation, plays crucial roles in survival and diseased conditions. Efforts were made to understand the role of autophagy in motor neuron degeneration and to target autophagy in motor neuron for ALS treatment. However, results were quite contradictory. Possible autophagy defects in other cell types may also complicate the results. Here, we examined autophagy activity in skeletal muscle of an ALS mouse model G93A. Through overexpression of a fluorescent protein LC3-RFP, we found a basal increase in autophagosome formation in G93A muscle during disease progression when the mice were on a regular diet. As expected, an autophagy induction procedure (starvation plus colchicine) enhanced autophagy flux in skeletal muscle of normal mice. However, in response to the same autophagy induction procedure, G93A muscle showed significant reduction in the autophagy flux. Immunoblot analysis revealed that increased cleaved caspase-3 associated with apoptosis was linked to the cleavage of several key proteins involved in autophagy, including Beclin-1, which is an essential molecule connecting autophagy and apoptosis pathways. Taking together, we provide the evidence that the cytoprotective autophagy pathway is suppressed in G93A skeletal muscle and this suppression may link to the enhanced apoptosis during ALS progression. The abnormal autophagy activity in skeletal muscle likely contributes muscle degeneration and disease progression in ALS.
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Affiliation(s)
- Yajuan Xiao
- Department of Molecular Biophysics and Physiology, Rush University School of Medicine, Chicago, Illinois Department of Physiology, Kansas City University of Medicine and Biosciences, Kansas City, Missouri
| | - Changling Ma
- Department of Molecular Biophysics and Physiology, Rush University School of Medicine, Chicago, Illinois
| | - Jianxun Yi
- Department of Molecular Biophysics and Physiology, Rush University School of Medicine, Chicago, Illinois Department of Physiology, Kansas City University of Medicine and Biosciences, Kansas City, Missouri
| | - Shaoping Wu
- Department of Biochemistry, Rush University School of Medicine, Chicago, Illinois
| | - Guo Luo
- Department of Molecular Biophysics and Physiology, Rush University School of Medicine, Chicago, Illinois
| | - Xiulong Xu
- Department of Cell Biology, Rush University School of Medicine, Chicago, Illinois
| | - Pei-Hui Lin
- Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Jun Sun
- Department of Biochemistry, Rush University School of Medicine, Chicago, Illinois
| | - Jingsong Zhou
- Department of Molecular Biophysics and Physiology, Rush University School of Medicine, Chicago, Illinois Department of Physiology, Kansas City University of Medicine and Biosciences, Kansas City, Missouri
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Ferrier A, De Repentigny Y, Lynch-Godrei A, Gibeault S, Eid W, Kuo D, Zha X, Kothary R. Disruption in the autophagic process underlies the sensory neuropathy in dystonia musculorum mice. Autophagy 2015; 11:1025-36. [PMID: 26043942 PMCID: PMC4590603 DOI: 10.1080/15548627.2015.1052207] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 04/23/2015] [Accepted: 05/11/2015] [Indexed: 12/27/2022] Open
Abstract
A homozygous mutation in the DST (dystonin) gene causes a newly identified lethal form of hereditary sensory and autonomic neuropathy in humans (HSAN-VI). DST loss of function similarly leads to sensory neuron degeneration and severe ataxia in dystonia musculorum (Dst(dt)) mice. DST is involved in maintaining cytoskeletal integrity and intracellular transport. As autophagy is highly reliant upon stable microtubules and motor proteins, we assessed the influence of DST loss of function on autophagy using the Dst(dt-Tg4) mouse model. Electron microscopy (EM) revealed an accumulation of autophagosomes in sensory neurons from these mice. Furthermore, we demonstrated that the autophagic flux was impaired. Levels of LC3-II, a marker of autophagosomes, were elevated. Consequently, Dst(dt-Tg4) sensory neurons displayed impaired protein turnover of autophagosome substrate SQTSM1/p62 and of polyubiquitinated proteins. Interestingly, in a previously described Dst(dt-Tg4) mouse model that is partially rescued by neuronal specific expression of the DST-A2 isoform, autophagosomes, autolysosomes, and damaged organelles were reduced when compared to Dst(dt-Tg4) mutant mice. LC3-II, SQTSM1, polyubiquitinated proteins and autophagic flux were also restored to wild-type levels in the rescued mice. Finally, a significant decrease in DNAIC1 (dynein, axonemal, intermediate chain 1; the mouse ortholog of human DNAI1), a member of the DMC (dynein/dynactin motor complex), was noted in Dst(dt-Tg4) dorsal root ganglia and sensory neurons. Thus, DST-A2 loss of function perturbs late stages of autophagy, and dysfunctional autophagy at least partially underlies Dst(dt) pathogenesis. We therefore conclude that the DST-A2 isoform normally facilitates autophagy within sensory neurons to maintain cellular homeostasis.
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Key Words
- ANOVA, analysis of variance
- BPAG1
- CASP3, caspase 3, apoptosis-related cysteine peptidase
- DMC
- DMC, dynein/dynactin motor complex
- DMEM, Dulbecco's modified Eagle's medium
- DNAIC1, dynein, axonemal, intermediate chain 1
- DRG, dorsal root ganglion
- DST, dystonin
- Dstdt, dystonia musculorum
- EM, electron microscopy
- FBS, fetal bovine serum
- HSAN-VI
- HSAN-VI, hereditary sensory and autonomic neuropathy type VI
- MACF1, microtubule-actin crosslinking factor 1
- MAP1B
- MAP1B, microtubule-associated protein 1B
- MAP1LC3/LC3, microtubule associated-protein 1 light chain 3
- MT, microtubule
- P, postnatal day
- PBS, phosphate-buffered saline
- PCR, polymerase chain reaction
- PrP, prion protein
- RT-PCR, reverse transcription-polymerase chain reaction
- SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis
- SQTSM1/p62, sequestosome 1
- TCA, trichloroacetic acid
- TUBB3, tubulin, β, 3 class III
- WT, wild type
- autophagosome
- dynein
- dystonin
- microtubules
- trafficking
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Affiliation(s)
- Andrew Ferrier
- Ottawa Hospital Research Institute; Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine; University of Ottawa; Ottawa, ON, Canada
| | | | - Anisha Lynch-Godrei
- Ottawa Hospital Research Institute; Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine; University of Ottawa; Ottawa, ON, Canada
| | | | - Walaa Eid
- Ottawa Hospital Research Institute; Ottawa, ON, Canada
- Department of Biochemistry; Microbiology; and Immunology; University of Ottawa; Ottawa, ON, Canada
| | - Daniel Kuo
- Ottawa Hospital Research Institute; Ottawa, ON, Canada
| | - Xiaohui Zha
- Ottawa Hospital Research Institute; Ottawa, ON, Canada
- Department of Biochemistry; Microbiology; and Immunology; University of Ottawa; Ottawa, ON, Canada
- Department of Medicine; University of Ottawa; Ottawa, ON, Canada
| | - Rashmi Kothary
- Ottawa Hospital Research Institute; Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine; University of Ottawa; Ottawa, ON, Canada
- Department of Medicine; University of Ottawa; Ottawa, ON, Canada
- University of Ottawa Center for Neuromuscular Disease; Ottawa, ON, Canada
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70
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Jenzer C, Simionato E, Legouis R. Tools and methods to analyze autophagy in C. elegans. Methods 2014; 75:162-71. [PMID: 25484340 DOI: 10.1016/j.ymeth.2014.11.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/24/2014] [Accepted: 11/25/2014] [Indexed: 11/27/2022] Open
Abstract
For a long time, autophagy has been mainly studied in yeast or mammalian cell lines, and assays for analyzing autophagy in these models have been well described. More recently, the involvement of autophagy in various physiological functions has been investigated in multicellular organisms. Modification of autophagy flux is involved in developmental processes, resistance to stress conditions, aging, cell death and multiple pathologies. So, the use of animal models is essential to understand these processes in the context of different cell types and during the whole life. For ten years, the nematode Caenorhabditis elegans has emerged as a powerful model to analyze autophagy in physiological or pathological contexts. In this article, we present some of the established approaches and the emerging tools available to monitor and manipulate autophagy in C. elegans, and discuss their advantages and limitations.
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Affiliation(s)
- Céline Jenzer
- Centre de Génétique Moléculaire, CNRS UPR3404, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, 1 Avenue de la Terrasse, 91198 Gif sur Yvette, France
| | - Elena Simionato
- Centre de Génétique Moléculaire, CNRS UPR3404, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, 1 Avenue de la Terrasse, 91198 Gif sur Yvette, France
| | - Renaud Legouis
- Centre de Génétique Moléculaire, CNRS UPR3404, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, 1 Avenue de la Terrasse, 91198 Gif sur Yvette, France.
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71
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Poppe L, Rué L, Robberecht W, Van Den Bosch L. Translating biological findings into new treatment strategies for amyotrophic lateral sclerosis (ALS). Exp Neurol 2014; 262 Pt B:138-51. [DOI: 10.1016/j.expneurol.2014.07.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 06/26/2014] [Accepted: 07/02/2014] [Indexed: 02/06/2023]
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Palomo GM, Manfredi G. Exploring new pathways of neurodegeneration in ALS: the role of mitochondria quality control. Brain Res 2014; 1607:36-46. [PMID: 25301687 DOI: 10.1016/j.brainres.2014.09.065] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 09/26/2014] [Accepted: 09/27/2014] [Indexed: 12/11/2022]
Abstract
Neuronal cells are highly dependent on mitochondria, and mitochondrial dysfunction is associated with neurodegenerative diseases. As perturbed mitochondrial function renders neurons extremely sensitive to a wide variety of insults, such as oxidative stress and bioenergetic defects, mitochondrial defects can profoundly affect neuronal fate. Several studies have linked ALS with mitochondrial dysfunction, stemming from observations of mitochondrial abnormalities, both in patients and in cellular and mouse models of familial forms of ALS. Mitochondrial changes have been thoroughly investigated in mutants of superoxide dismutase 1 (SOD1), one of the most common causes of familial ALS, for which excellent cellular and animal models are available, but recently evidence is emerging also in other forms of ALS, both familial and sporadic. Mitochondrial defects in ALS involve many critical physiopathological processes, from defective bioenergetics to abnormal calcium homeostasis, altered morphology and impaired trafficking. In this review, we summarize established evidence of mitochondrial dysfunction in ALS, especially in SOD1 mutant models of familial ALS. The main focus of the review is on defective mitochondrial quality control (MQC) in ALS. MQC operates at multiple levels to clear damaged proteins through proteostasis and to eliminate irreparably damaged organelles through mitophagy. However, since ALS motor neurons progressively accumulate damaged mitochondria, it is plausible that the MQC is ineffective or overwhelmed by excessive workload imposed by the chronic and extensive mitochondrial damage. This article is part of a Special Issue entitled ALS complex pathogenesis.
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Affiliation(s)
- Gloria M Palomo
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, United States
| | - Giovanni Manfredi
- Brain and Mind Research Institute, Weill Medical College of Cornell University, New York, NY 10065, United States.
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73
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Polajnar M, Zerovnik E. Impaired autophagy: a link between neurodegenerative and neuropsychiatric diseases. J Cell Mol Med 2014; 18:1705-11. [PMID: 25139375 PMCID: PMC4196646 DOI: 10.1111/jcmm.12349] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Accepted: 05/16/2014] [Indexed: 12/12/2022] Open
Abstract
Protein misfolding, and subsequent aggregation have been proven as the leading cause of most known dementias. Many of these, in addition to neurodegeneration, show profound changes in behaviour and thinking, thus, psychiatric symptoms. On the basis of the observation that progressive myoclonic epilepsies and neurodegenerative diseases share some common features of neurodegeneration, we proposed autophagy as a possible common impairment in these diseases. Here, we argue along similar lines for some neuropsychiatric conditions, among them depression and schizophrenia. We propose that existing and new therapies for these seemingly different diseases could be augmented with drugs used for neurodegenerative or neuropsychiatric diseases, respectively, among them some which modulate or augment autophagy.
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Affiliation(s)
- Mira Polajnar
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
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74
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Profilin 1 associates with stress granules and ALS-linked mutations alter stress granule dynamics. J Neurosci 2014; 34:8083-97. [PMID: 24920614 DOI: 10.1523/jneurosci.0543-14.2014] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mutations in the PFN1 gene encoding profilin 1 are a rare cause of familial amyotrophic lateral sclerosis (ALS). Profilin 1 is a well studied actin-binding protein but how PFN1 mutations cause ALS is unknown. The budding yeast, Saccharomyces cerevisiae, has one PFN1 ortholog. We expressed the ALS-linked profilin 1 mutant proteins in yeast, demonstrating a loss of protein stability and failure to restore growth to profilin mutant cells, without exhibiting gain-of-function toxicity. This model provides for simple and rapid screening of novel ALS-linked PFN1 variants. To gain insight into potential novel roles for profilin 1, we performed an unbiased, genome-wide synthetic lethal screen with yeast cells lacking profilin (pfy1Δ). Unexpectedly, deletion of several stress granule and processing body genes, including pbp1Δ, were found to be synthetic lethal with pfy1Δ. Mutations in ATXN2, the human ortholog of PBP1, are a known ALS genetic risk factor and ataxin 2 is a stress granule component in mammalian cells. Given this genetic interaction and recent evidence linking stress granule dynamics to ALS pathogenesis, we hypothesized that profilin 1 might also associate with stress granules. Here we report that profilin 1 and related protein profilin 2 are novel stress granule-associated proteins in mouse primary cortical neurons and in human cell lines and that ALS-linked mutations in profilin 1 alter stress granule dynamics, providing further evidence for the potential role of stress granules in ALS pathogenesis.
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75
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Smith GA, Rocha EM, McLean JR, Hayes MA, Izen SC, Isacson O, Hallett PJ. Progressive axonal transport and synaptic protein changes correlate with behavioral and neuropathological abnormalities in the heterozygous Q175 KI mouse model of Huntington's disease. Hum Mol Genet 2014; 23:4510-27. [PMID: 24728190 DOI: 10.1093/hmg/ddu166] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A long-term goal of modeling Huntington's disease (HD) is to recapitulate the cardinal features of the disease in mice that express both mutant and wild-type (WT) huntingtin (Htt), as HD commonly manifests as a heterozygous condition in humans, and loss of WT Htt is associated with loss-of-function. In a new heterozygous Q175 knock-in (KI) mouse model, we performed an extensive evaluation of motor and cognitive functional deficits, neuropathological and biochemical changes and levels of proteins involved in synaptic function, the cytoskeleton and axonal transport, at 1-16 months of age. Motor deficits were apparent at 6 months of age in Q175 KI mice and at that time, postmortem striatal gamma-aminobutyric acid (GABA) levels were elevated and mutant Htt inclusions were present throughout the brain. From 6 months of age, levels of proteins associated with synaptic function, including SNAP-25, Rab3A and PSD-95, and with axonal transport and microtubules, including KIF3A, dynein and dynactin, were altered in the striatum, motor cortex, prefrontal cortex and hippocampus of Q175 KI mice, compared with WT levels. At 12-16 months of age, Q175 KI mice displayed motor and cognitive deficits, which were paralleled at postmortem by striatal atrophy, cortical thinning, degeneration of medium spiny neurons, dense mutant Htt inclusion formation, decreased striatal dopamine levels and loss of striatal brain-derived neurotrophic factor (BDNF). Data from this study indicate that the heterozygous Q175 KI mouse represents a realistic model for HD and also provides new insights into the specific and progressive synaptic, cytoskeletal and axonal transport protein abnormalities that may accompany the disease.
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Affiliation(s)
- Gaynor A Smith
- McLean Hospital/Harvard Medical School, Neuroregeneration Research Institute and Laboratories, Belmont, MA, USA
| | - Emily M Rocha
- McLean Hospital/Harvard Medical School, Neuroregeneration Research Institute and Laboratories, Belmont, MA, USA
| | - Jesse R McLean
- McLean Hospital/Harvard Medical School, Neuroregeneration Research Institute and Laboratories, Belmont, MA, USA
| | - Melissa A Hayes
- McLean Hospital/Harvard Medical School, Neuroregeneration Research Institute and Laboratories, Belmont, MA, USA
| | - Sarah C Izen
- McLean Hospital/Harvard Medical School, Neuroregeneration Research Institute and Laboratories, Belmont, MA, USA
| | - Ole Isacson
- McLean Hospital/Harvard Medical School, Neuroregeneration Research Institute and Laboratories, Belmont, MA, USA
| | - Penelope J Hallett
- McLean Hospital/Harvard Medical School, Neuroregeneration Research Institute and Laboratories, Belmont, MA, USA
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The regulation of autophagosome dynamics by huntingtin and HAP1 is disrupted by expression of mutant huntingtin, leading to defective cargo degradation. J Neurosci 2014; 34:1293-305. [PMID: 24453320 DOI: 10.1523/jneurosci.1870-13.2014] [Citation(s) in RCA: 265] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Autophagy is an essential cellular pathway for degrading defective organelles and aggregated proteins. Defects in autophagy have been implicated in the neurodegenerative disorder Huntington's disease (HD), in which polyglutamine-expanded huntingtin (polyQ-htt) is predominantly cleared by autophagy. In neurons, autophagosomes form constitutively at the axon tip and undergo robust retrograde axonal transport toward the cell body, but the factors regulating autophagosome dynamics and autophagosome maturation are not well understood. Here, we show that both huntingtin (htt) and its adaptor protein huntingtin-associated protein-1 (HAP1) copurify and colocalize with autophagosomes in neurons. We use live-cell imaging and RNAi in primary neurons from GFP-LC3 transgenic mice to show that htt and HAP1 control autophagosome dynamics, regulating dynein and kinesin motors to promote processive transport. Expression of polyQ-htt in either primary neurons or striatal cells from HD knock-in mice is sufficient to disrupt the axonal transport of autophagosomes. Htt is not required for autophagosome formation or cargo loading. However, the defective autophagosome transport observed in both htt-depleted neurons and polyQ-htt-expressing neurons is correlated with inefficient degradation of engulfed mitochondrial fragments. Together, these studies identify htt and HAP1 as regulators of autophagosome transport in neurons and suggest that misregulation of autophagosome transport in HD leads to inefficient autophagosome maturation, potentially due to inhibition of autophagosome/lysosome fusion along the axon. The resulting defective clearance of both polyQ-htt aggregates and dysfunctional mitochondria by neuronal autophagosomes may contribute to neurodegeneration and cell death in HD.
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77
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Katsuno M, Ikenaka K, Kawai K, Sobue G. [Dysfunction of dynactin 1 in motor neuron degeneration]. Rinsho Shinkeigaku 2013; 53:1084-6. [PMID: 24291886 DOI: 10.5692/clinicalneurol.53.1084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Dynactin 1 is an axon motor protein regulating retrograde transport of various proteins and vesicles including autophagosome. We previously demonstrated that the expression levels of dynacin 1 are markedly reduced in spinal motor neurons of sporadic ALS patients. We generated a Caenorhabditis elegans model in which the expression of dnc-1, the homolog of dynactin 1, is specifically knocked down in motor neurons. This model exhibited severe motor defects together with axonal and neuronal degeneration. We also observed the impaired movement and increased number of autophagosomes in the degenerated neurons. Furthermore, the combination of rapamycin, an activator of autophagy, and trichostatin which facilitates axonal transport dramatically ameliorated the motor phenotype and axonal degeneration of this model. Thus, our results suggest that decreased expression of dynactin 1 induces motor neuron degeneration and that the transport of autophagosomes is a novel and substantial therapeutic target for motor neuron degeneration.
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Affiliation(s)
- Masahisa Katsuno
- Department of Neurology, Nagoya University Graduate School of Medicine
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78
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Autophagy in aging and neurodegenerative diseases: implications for pathogenesis and therapy. Neurobiol Aging 2013; 35:941-57. [PMID: 24360503 DOI: 10.1016/j.neurobiolaging.2013.11.019] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 11/17/2013] [Accepted: 11/19/2013] [Indexed: 12/12/2022]
Abstract
Neurodegenerative diseases, such as Alzheimer's disease Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis, share a common cellular and molecular pathogenetic mechanism involving aberrant misfolded protein or peptide aggregation and deposition. Autophagy represents a major route for degradation of aggregated cellular proteins and dysfunctional organelles. Emerging studies have demonstrated that up-regulation of autophagy can lead to decreased levels of these toxic aggregate-prone proteins, and is beneficial in the context of aging and various models of neurodegenerative diseases. Understanding the signaling pathways involved in the regulation of autophagy is crucial to the development of strategies for therapy. This review will discuss the cellular and molecular mechanisms of autophagy and its important role in the pathogenesis of aging and neurodegenerative diseases, and the ongoing drug discovery strategies for therapeutic modulation.
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79
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Kuźma-Kozakiewicz M, Chudy A, Kaźmierczak B, Dziewulska D, Usarek E, Barańczyk-Kuźma A. Dynactin Deficiency in the CNS of Humans with Sporadic ALS and Mice with Genetically Determined Motor Neuron Degeneration. Neurochem Res 2013; 38:2463-2473. [PMID: 24078265 PMCID: PMC3898179 DOI: 10.1007/s11064-013-1160-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 09/11/2013] [Accepted: 09/18/2013] [Indexed: 11/24/2022]
Abstract
Dynactin is a complex motor protein involved in the retrograde axonal transport disturbances of which may lead to amyotrophic lateral sclerosis (ALS). Mice with hSOD1G93A mutation develop ALS-like symptoms and are used as a model for the disease studies. Similar symptoms demonstrate Cra1 mice, with Dync1h1 mutation. Dynactin heavy (DCTN1) and light (DCTN3) subunits were studied in the CNS of humans with sporadic ALS (SALS), mice with hSOD1G93A (SOD1/+), Dync1h1 (Cra1/+), and double (Cra1/SOD1) mutation at presymptomatic and symptomatic stages. In SALS subjects, in contrast to control cases, expression of DCTN1-mRNA but not DCTN3-mRNA in the motor cortex was higher than in the sensory cortex. However, the mean levels of DCTN1-mRNA and protein were lower in both SALS cortexes and in the spinal cord than in control structures. DCTN3 was unchanged in brain cortexes but decreased in the spinal cord on both mRNA and protein levels. In all SALS tissues immunohistochemical analyses revealed degeneration and loss of neuronal cells, and poor expression of dynactin subunits. In SOD1/+ mice both subunits expression was significantly lower in the frontal cortex, spinal cord and hippocampus than in wild-type controls, especially at presymptomatic stage. Fewer changes occurred in Cra1/SOD1 and Cra1/+ mice.It can be concluded that in sporadic and SOD1-related ALS the impairment of axonal retrograde transport may be due to dynactin subunits deficiency and subsequent disturbances of the whole dynein/dynactin complex structure and function. The Dync1h1 mutation itself has slight negative effect on dynactin expression and it alleviates the changes caused by SOD1G93A mutation.
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Affiliation(s)
- Magdalena Kuźma-Kozakiewicz
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
- Neurodegenerative Diseases Research Group, Medical University of Warsaw, Warsaw, Poland
| | - Agnieszka Chudy
- Department of Biochemistry, Medical University of Warsaw, Banacha 1, 02-097 Warsaw, Poland
| | - Beata Kaźmierczak
- Department of Biochemistry, Medical University of Warsaw, Banacha 1, 02-097 Warsaw, Poland
- Neurodegenerative Diseases Research Group, Medical University of Warsaw, Warsaw, Poland
| | - Dorota Dziewulska
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
- Department of Experimental and Clinical Neuropathology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Warsaw, Poland
| | - Ewa Usarek
- Department of Biochemistry, Medical University of Warsaw, Banacha 1, 02-097 Warsaw, Poland
| | - Anna Barańczyk-Kuźma
- Department of Biochemistry, Medical University of Warsaw, Banacha 1, 02-097 Warsaw, Poland
- Neurodegenerative Diseases Research Group, Medical University of Warsaw, Warsaw, Poland
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