1
|
Iyer AK, Schoch KM, Verbeck A, Galasso G, Chen H, Smith S, Oldenborg A, Miller TM, Karch CM, Bonni A. Targeted ASO-mediated Atp1a2 knockdown in astrocytes reduces SOD1 aggregation and accelerates disease onset in mutant SOD1 mice. PLoS One 2023; 18:e0294731. [PMID: 38015828 PMCID: PMC10683999 DOI: 10.1371/journal.pone.0294731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 11/07/2023] [Indexed: 11/30/2023] Open
Abstract
Astrocyte-specific ion pump α2-Na+/K+-ATPase plays a critical role in the pathogenesis of amyotrophic lateral sclerosis (ALS). Here, we test the effect of Atp1a2 mRNA-specific antisense oligonucleotides (ASOs) to induce α2-Na+/K+-ATPase knockdown in the widely used ALS animal model, SOD1*G93A mice. Two ASOs led to efficient Atp1a2 knockdown and significantly reduced SOD1 aggregation in vivo. Although Atp1a2 ASO-treated mice displayed no off-target or systemic toxicity, the ASO-treated mice exhibited an accelerated disease onset and shorter lifespan than control mice. Transcriptomics studies reveal downregulation of genes involved in oxidative response, metabolic pathways, trans-synaptic signaling, and upregulation of genes involved in glutamate receptor signaling and complement activation, suggesting a potential role for these molecular pathways in de-coupling SOD1 aggregation from survival in Atp1a2 ASO-treated mice. Together, these results reveal a role for α2-Na+/K+-ATPase in SOD1 aggregation and highlight the critical effect of temporal modulation of genetically validated therapeutic targets in neurodegenerative diseases.
Collapse
Affiliation(s)
- Abhirami K. Iyer
- Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kathleen M. Schoch
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Anthony Verbeck
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Grant Galasso
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Hao Chen
- Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Sarah Smith
- Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Anna Oldenborg
- Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Timothy M. Miller
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Celeste M. Karch
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Azad Bonni
- Neuroscience and Rare Diseases, Roche Pharma Research and Early Development (pRED), Roche Innovation Centre Basel, Basel, Switzerland
| |
Collapse
|
2
|
Zhang X, Lee W, Bian JS. Recent Advances in the Study of Na +/K +-ATPase in Neurodegenerative Diseases. Cells 2022; 11:cells11244075. [PMID: 36552839 PMCID: PMC9777075 DOI: 10.3390/cells11244075] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 12/11/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Na+/K+-ATPase (NKA), a large transmembrane protein, is expressed in the plasma membrane of most eukaryotic cells. It maintains resting membrane potential, cell volume and secondary transcellular transport of other ions and neurotransmitters. NKA consumes about half of the ATP molecules in the brain, which makes NKA highly sensitive to energy deficiency. Neurodegenerative diseases (NDDs) are a group of diseases characterized by chronic, progressive and irreversible neuronal loss in specific brain areas. The pathogenesis of NDDs is sophisticated, involving protein misfolding and aggregation, mitochondrial dysfunction and oxidative stress. The protective effect of NKA against NDDs has been emerging gradually in the past few decades. Hence, understanding the role of NKA in NDDs is critical for elucidating the underlying pathophysiology of NDDs and identifying new therapeutic targets. The present review focuses on the recent progress involving different aspects of NKA in cellular homeostasis to present in-depth understanding of this unique protein. Moreover, the essential roles of NKA in NDDs are discussed to provide a platform and bright future for the improvement of clinical research in NDDs.
Collapse
Affiliation(s)
- Xiaoyan Zhang
- Department of Pharmacology, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Weithye Lee
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117600, Singapore
| | - Jin-Song Bian
- Department of Pharmacology, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
- Correspondence:
| |
Collapse
|
3
|
Calabrese G, Molzahn C, Mayor T. Protein interaction networks in neurodegenerative diseases: from physiological function to aggregation. J Biol Chem 2022; 298:102062. [PMID: 35623389 PMCID: PMC9234719 DOI: 10.1016/j.jbc.2022.102062] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/26/2022] [Accepted: 05/18/2022] [Indexed: 11/25/2022] Open
Abstract
The accumulation of protein inclusions is linked to many neurodegenerative diseases that typically develop in older individuals, due to a combination of genetic and environmental factors. In rare familial neurodegenerative disorders, genes encoding for aggregation-prone proteins are often mutated. While the underlying mechanism leading to these diseases still remains to be fully elucidated, efforts in the past 20 years revealed a vast network of protein–protein interactions that play a major role in regulating the aggregation of key proteins associated with neurodegeneration. Misfolded proteins that can oligomerize and form insoluble aggregates associate with molecular chaperones and other elements of the proteolytic machineries that are the frontline workers attempting to protect the cells by promoting clearance and preventing aggregation. Proteins that are normally bound to aggregation-prone proteins can become sequestered and mislocalized in protein inclusions, leading to their loss of function. In contrast, mutations, posttranslational modifications, or misfolding of aggregation-prone proteins can lead to gain of function by inducing novel or altered protein interactions, which in turn can impact numerous essential cellular processes and organelles, such as vesicle trafficking and the mitochondria. This review examines our current knowledge of protein–protein interactions involving several key aggregation-prone proteins that are associated with Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, or amyotrophic lateral sclerosis. We aim to provide an overview of the protein interaction networks that play a central role in driving or mitigating inclusion formation, while highlighting some of the key proteomic studies that helped to uncover the extent of these networks.
Collapse
Affiliation(s)
- Gaetano Calabrese
- Michael Smith Laboratories, University of British Columbia, V6T 1Z4 Vancouver BC, Canada.
| | - Cristen Molzahn
- Michael Smith Laboratories, University of British Columbia, V6T 1Z4 Vancouver BC, Canada
| | - Thibault Mayor
- Michael Smith Laboratories, University of British Columbia, V6T 1Z4 Vancouver BC, Canada.
| |
Collapse
|
4
|
Une M, Yamakawa M, Watanabe Y, Uchino K, Honda N, Adachi M, Nakanishi M, Umezawa A, Kawata Y, Nakashima K, Hanajima R. SOD1-interacting proteins: Roles of aggregation cores and protein degradation systems. Neurosci Res 2020; 170:295-305. [PMID: 32726594 DOI: 10.1016/j.neures.2020.07.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 07/15/2020] [Accepted: 07/15/2020] [Indexed: 11/26/2022]
Abstract
Cu/Zn superoxide dismutase (SOD1) mutations are associated with amyotrophic lateral sclerosis (ALS). SOD1-positive aggregates in motor neurons, as well as proteins that interact with the aggregates are presumably involved in ALS neurotoxicity. We used a proteomics approach to compare differences in protein expression in spinal cord homogenates from non-transgenic (NTG) and ALS model mice. Using the homogenates, we identified proteins that interacted with SOD1 seeds in vitro. We assessed differences in SOD1-interacting proteins in cell cultures treated with proteasome or autophagy inhibitor. In the first experiment, intermediate filamentous and small heat shock proteins were upregulated in glial cells. We identified 26 protein types that interacted with aggregation cores in ALS model homogenates, and unexpectedly, 40 proteins in were detected in NTG mice. In cell cultures treated with proteasome and autophagy inhibitors, we identified 16 and 11 SOD1-interacting proteins, respectively, and seven proteins in untreated cells. These SOD1-interacting proteins were involved in multiple cellular functions such as protein quality control, cytoskeletal organization, and pathways involved in growth factor signaling and their downstream cascades. The complex interactions between pathways could cause further dysregulation, ultimately leading to fatal cellular dysfunction in ALS.
Collapse
Affiliation(s)
- Mio Une
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Miho Yamakawa
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Yasuhiro Watanabe
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan.
| | - Kazuyuki Uchino
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Tottori, Japan
| | - Naoto Honda
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Mayuka Adachi
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Mami Nakanishi
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Akihiro Umezawa
- Center for Regenerative Medicine, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Yasushi Kawata
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Tottori, Japan
| | - Kenji Nakashima
- Department of Neurology, National Hospital Organization, Matsue Medical Center, Matsue, Japan
| | - Ritsuko Hanajima
- Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
| |
Collapse
|
5
|
Semmler S, Gagné M, Garg P, Pickles SR, Baudouin C, Hamon-Keromen E, Destroismaisons L, Khalfallah Y, Chaineau M, Caron E, Bayne AN, Trempe JF, Cashman NR, Star AT, Haqqani AS, Durcan TM, Meiering EM, Robertson J, Grandvaux N, Plotkin SS, McBride HM, Vande Velde C. TNF receptor-associated factor 6 interacts with ALS-linked misfolded superoxide dismutase 1 and promotes aggregation. J Biol Chem 2020; 295:3808-3825. [PMID: 32029478 DOI: 10.1074/jbc.ra119.011215] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 01/17/2020] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal disease, characterized by the selective loss of motor neurons leading to paralysis. Mutations in the gene encoding superoxide dismutase 1 (SOD1) are the second most common cause of familial ALS, and considerable evidence suggests that these mutations result in an increase in toxicity due to protein misfolding. We previously demonstrated in the SOD1G93A rat model that misfolded SOD1 exists as distinct conformers and forms deposits on mitochondrial subpopulations. Here, using SOD1G93A rats and conformation-restricted antibodies specific for misfolded SOD1 (B8H10 and AMF7-63), we identified the interactomes of the mitochondrial pools of misfolded SOD1. This strategy identified binding proteins that uniquely interacted with either AMF7-63 or B8H10-reactive SOD1 conformers as well as a high proportion of interactors common to both conformers. Of this latter set, we identified the E3 ubiquitin ligase TNF receptor-associated factor 6 (TRAF6) as a SOD1 interactor, and we determined that exposure of the SOD1 functional loops facilitates this interaction. Of note, this conformational change was not universally fulfilled by all SOD1 variants and differentiated TRAF6 interacting from TRAF6 noninteracting SOD1 variants. Functionally, TRAF6 stimulated polyubiquitination and aggregation of the interacting SOD1 variants. TRAF6 E3 ubiquitin ligase activity was required for the former but was dispensable for the latter, indicating that TRAF6-mediated polyubiquitination and aggregation of the SOD1 variants are independent events. We propose that the interaction between misfolded SOD1 and TRAF6 may be relevant to the etiology of ALS.
Collapse
Affiliation(s)
- Sabrina Semmler
- Department of Neurology and Neurosurgery, McGill University, Montréal, Quebec H3A 2B4, Canada.,Centre de Recherche du Centre Hospitalier de Université de Montréal, Montréal, Quebec H2X 0A9, Canada
| | - Myriam Gagné
- Centre de Recherche du Centre Hospitalier de Université de Montréal, Montréal, Quebec H2X 0A9, Canada.,Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Pranav Garg
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Sarah R Pickles
- Centre de Recherche du Centre Hospitalier de Université de Montréal, Montréal, Quebec H2X 0A9, Canada.,Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Charlotte Baudouin
- Centre de Recherche du Centre Hospitalier de Université de Montréal, Montréal, Quebec H2X 0A9, Canada.,Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium
| | - Emeline Hamon-Keromen
- Centre de Recherche du Centre Hospitalier de Université de Montréal, Montréal, Quebec H2X 0A9, Canada.,Université Pierre et Marie Curie, 75005 Paris, France
| | - Laurie Destroismaisons
- Centre de Recherche du Centre Hospitalier de Université de Montréal, Montréal, Quebec H2X 0A9, Canada
| | - Yousra Khalfallah
- Centre de Recherche du Centre Hospitalier de Université de Montréal, Montréal, Quebec H2X 0A9, Canada.,Department of Neurosciences, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Mathilde Chaineau
- Department of Neurology and Neurosurgery, McGill University, Montréal, Quebec H3A 2B4, Canada.,Montreal Neurological Institute, McGill University, Montréal, Quebec H3A 2B4, Canada
| | - Elise Caron
- Centre de Recherche du Centre Hospitalier de Université de Montréal, Montréal, Quebec H2X 0A9, Canada
| | - Andrew N Bayne
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Quebec H3A 2B4, Canada
| | - Jean-François Trempe
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Quebec H3A 2B4, Canada
| | - Neil R Cashman
- Department of Medicine (Neurology), University of British Columbia and Vancouver Coastal Health Research Institute, Brain Research Centre, Vancouver, British Columbia V6T 2B5, Canada
| | - Alexandra T Star
- Human Health Therapeutics Portfolio, National Research Council of Canada, Ottawa, Ontario, K1A 0R6, Canada
| | - Arsalan S Haqqani
- Human Health Therapeutics Portfolio, National Research Council of Canada, Ottawa, Ontario, K1A 0R6, Canada
| | - Thomas M Durcan
- Department of Neurology and Neurosurgery, McGill University, Montréal, Quebec H3A 2B4, Canada.,Montreal Neurological Institute, McGill University, Montréal, Quebec H3A 2B4, Canada
| | - Elizabeth M Meiering
- Department of Chemistry, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Janice Robertson
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario M5T 0S8, Canada
| | - Nathalie Grandvaux
- Centre de Recherche du Centre Hospitalier de Université de Montréal, Montréal, Quebec H2X 0A9, Canada.,Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Steven S Plotkin
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Heidi M McBride
- Department of Neurology and Neurosurgery, McGill University, Montréal, Quebec H3A 2B4, Canada.,Montreal Neurological Institute, McGill University, Montréal, Quebec H3A 2B4, Canada
| | - Christine Vande Velde
- Centre de Recherche du Centre Hospitalier de Université de Montréal, Montréal, Quebec H2X 0A9, Canada .,Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec H3T 1J4, Canada.,Department of Neurosciences, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| |
Collapse
|
6
|
Huai J, Zhang Z. Structural Properties and Interaction Partners of Familial ALS-Associated SOD1 Mutants. Front Neurol 2019; 10:527. [PMID: 31164862 PMCID: PMC6536575 DOI: 10.3389/fneur.2019.00527] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 05/02/2019] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common motor neuron degenerative disease in adults and has also been proven to be a type of conformational disease associated with protein misfolding and dysfunction. To date, more than 150 distinct genes have been found to be associated with ALS, among which Superoxide Dismutase 1 (SOD1) is the first and the most extensively studied gene. It has been well-established that SOD1 mutants-mediated toxicity is caused by a gain-of-function rather than the loss of the detoxifying activity of SOD1. Compared with the clear autosomal dominant inheritance of SOD1 mutants in ALS, the potential toxic mechanisms of SOD1 mutants in motor neurons remain incompletely understood. A large body of evidence has shown that SOD1 mutants may adopt a complex profile of conformations and interact with a wide range of client proteins. Here, in this review, we summarize the fundamental conformational properties and the gained interaction partners of the soluble forms of the SOD1 mutants which have been published in the past decades. Our goal is to find clues to the possible internal links between structural and functional anomalies of SOD1 mutants, as well as the relationships between their exposed epitopes and interaction partners, in order to help reveal and determine potential diagnostic and therapeutic targets.
Collapse
Affiliation(s)
- Jisen Huai
- Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Zhongjian Zhang
- Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| |
Collapse
|
7
|
Structural and kinetic analysis of protein-aggregate strains in vivo using binary epitope mapping. Proc Natl Acad Sci U S A 2015; 112:4489-94. [PMID: 25802384 DOI: 10.1073/pnas.1419228112] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Despite considerable progress in uncovering the molecular details of protein aggregation in vitro, the cause and mechanism of protein-aggregation disease remain poorly understood. One reason is that the amount of pathological aggregates in neural tissue is exceedingly low, precluding examination by conventional approaches. We present here a method for determination of the structure and quantity of aggregates in small tissue samples, circumventing the above problem. The method is based on binary epitope mapping using anti-peptide antibodies. We assessed the usefulness and versatility of the method in mice modeling the neurodegenerative disease amyotrophic lateral sclerosis, which accumulate intracellular aggregates of superoxide dismutase-1. Two strains of aggregates were identified with different structural architectures, molecular properties, and growth kinetics. Both were different from superoxide dismutase-1 aggregates generated in vitro under a variety of conditions. The strains, which seem kinetically under fragmentation control, are associated with different disease progressions, complying with and adding detail to the growing evidence that seeding, infectivity, and strain dependence are unifying principles of neurodegenerative disease.
Collapse
|
8
|
Analysis of mutant SOD1 electrophoretic mobility by Blue Native gel electrophoresis; evidence for soluble multimeric assemblies. PLoS One 2014; 9:e104583. [PMID: 25121776 PMCID: PMC4133237 DOI: 10.1371/journal.pone.0104583] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 07/14/2014] [Indexed: 12/12/2022] Open
Abstract
Mutations in superoxide dismutase 1 (SOD1) cause familial forms of amyotrophic lateral sclerosis (fALS). Disease causing mutations have diverse consequences on the activity and half-life of the protein, ranging from complete inactivity and short half-life to full activity and long-half-life. Uniformly, disease causing mutations induce the protein to misfold and aggregate and such aggregation tendencies are readily visualized by over-expression of the proteins in cultured cells. In the present study we have investigated the potential of using immunoblotting of proteins separated by Blue-Native gel electrophoresis (BNGE) as a means to identify soluble multimeric forms of mutant protein. We find that over-expressed wild-type human SOD1 (hSOD1) is generally not prone to form soluble high molecular weight entities that can be separated by BNGE. For ALS mutant SOD1, we observe that for all mutants examined (A4V, G37R, G85R, G93A, and L126Z), immunoblots of BN-gels separating protein solubilized by digitonin demonstrated varied amounts of high molecular weight immunoreactive entities. These entities lacked reactivity to ubiquitin and were partially dissociated by reducing agents. With the exception of the G93A mutant, these entities were not reactive to the C4F6 conformational antibody. Collectively, these data demonstrate that BNGE can be used to assess the formation of soluble multimeric assemblies of mutant SOD1.
Collapse
|
9
|
Molecular chaperone Hsp110 rescues a vesicle transport defect produced by an ALS-associated mutant SOD1 protein in squid axoplasm. Proc Natl Acad Sci U S A 2013; 110:5428-33. [PMID: 23509252 DOI: 10.1073/pnas.1303279110] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mutant human Cu/Zn superoxide dismutase 1 (SOD1) is associated with motor neuron toxicity and death in an inherited form of amyotrophic lateral sclerosis (ALS; Lou Gehrig disease). One aspect of toxicity in motor neurons involves diminished fast axonal transport, observed both in transgenic mice and, more recently, in axoplasm isolated from squid giant axons. The latter effect appears to be directly mediated by misfolded SOD1, whose addition activates phosphorylation of p38 MAPK and phosphorylation of kinesin. Here, we observe that several different oligomeric states of a fusion protein, comprising ALS-associated human G85R SOD1 joined with yellow fluorescent protein (G85R SOD1YFP), which produces ALS in transgenic mice, inhibited anterograde transport when added to squid axoplasm. Inhibition was blocked both by an apoptosis signal-regulating kinase 1 (ASK1; MAPKKK) inhibitor and by a p38 inhibitor, indicating the transport defect is mediated through the MAPK cascade. In further incubations, we observed that addition of the mammalian molecular chaperone Hsc70, abundantly associated with G85R SOD1YFP in spinal cord of transgenic mice, exerted partial correction of the transport defect, associated with diminished phosphorylation of p38. Most striking, the addition of the molecular chaperone Hsp110, in a concentration substoichiometric to the mutant SOD1 protein, completely rescued both the transport defect and the phosphorylation of p38. Hsp110 has been demonstrated to act as a nucleotide exchange factor for Hsc70 and, more recently, to be able to cooperate with it to mediate protein disaggregation. We speculate that it can cooperate with endogenous squid Hsp(c)70 to mediate binding and/or disaggregation of mutant SOD1 protein, abrogating toxicity.
Collapse
|
10
|
Zetterström P, Graffmo KS, Andersen PM, Brännström T, Marklund SL. Proteins that bind to misfolded mutant superoxide dismutase-1 in spinal cords from transgenic amyotrophic lateral sclerosis (ALS) model mice. J Biol Chem 2011; 286:20130-6. [PMID: 21493711 DOI: 10.1074/jbc.m111.218842] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutant superoxide dismutase-1 (SOD1) has an unidentified toxic property that provokes ALS. Several ALS-linked SOD1 mutations cause long C-terminal truncations, which suggests that common cytotoxic SOD1 conformational species should be misfolded and that the C-terminal end cannot be involved. The cytotoxicity may arise from interaction of cellular proteins with misfolded SOD1 species. Here we specifically immunocaptured misfolded SOD1 by the C-terminal end, from extracts of spinal cords from transgenic ALS model mice. Associated proteins were identified with proteomic techniques. Two transgenic models expressing SOD1s with contrasting molecular properties were examined: the stable G93A mutant, which is abundant in the spinal cord with only a tiny subfraction misfolded, and the scarce disordered truncation mutant G127insTGGG. For comparison, proteins in spinal cord extracts with affinity for immobilized apo G93A mutant SOD1 were determined. Two-dimensional gel patterns with a limited number of bound proteins were found, which were similar for the two SOD1 mutants. Apart from neurofilament light, the proteins identified were all chaperones and by far most abundant was Hsc70. The immobilized apo G93A SOD1, which would populate a variety of conformations, was found to bind to a considerable number of additional proteins. A substantial proportion of the misfolded SOD1 in the spinal cord extracts appeared to be chaperone-associated. Still, only about 1% of the Hsc70 appeared to be associated with misfolded SOD1. The results argue against the notion that chaperone depletion is involved in ALS pathogenesis in the transgenic models and in humans carrying SOD1 mutations.
Collapse
Affiliation(s)
- Per Zetterström
- Department of Medical Biosciences, Clinical Chemistry, Umeå University, SE-901 85 Umeå, Sweden
| | | | | | | | | |
Collapse
|
11
|
Mali Y, Zisapel N. A novel decoy that interrupts G93A-superoxide dismutase gain of interaction with malate dehydrogenase improves survival in an amyotrophic lateral sclerosis cell model. J Med Chem 2009; 52:5442-8. [PMID: 19670830 DOI: 10.1021/jm900631m] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human G93A-superoxide dismutase-1 (G93AhSOD1) mutation causes amyotrophic lateral sclerosis (ALS) in rodents and humans. Recent observations indicate gain of interaction of G93AhSOD1 with cytosolic malate dehydrogenase (MDH1) and subsequent impairment in the malate aspartate shuttle which is vital to neurons. Using fluorescence resonance energy transfer (FRET), we screened an MDH1 derived peptide library for a decoy that would interrupt the G93AhSOD1-MDH1 interaction. A specific 23 amino acid blocker of this interaction was thus discovered, and interruption of interaction was confirmed by pull-down immunoprecipitation studies. A cell permeable 5-carboxytetramethylrhodamine derivative of the decoy peptide improved ATP content of motor neuron derived NSC-34 cells expressing G93AhSOD1 and enhanced cell survival under rotenone and low glucose challenges. Decoy agents capable of interrupting the gain of toxic interaction of G93AhSOD1 with MDH1 provide further evidence for the role of malate aspartate shuttle inhibition in G93AhSOD1 toxicity and a promising new route in ALS drug research.
Collapse
Affiliation(s)
- Yael Mali
- Department of Neurobiology, Tel Aviv University, Tel Aviv 69978, Israel
| | | |
Collapse
|
12
|
Progressive aggregation despite chaperone associations of a mutant SOD1-YFP in transgenic mice that develop ALS. Proc Natl Acad Sci U S A 2009; 106:1392-7. [PMID: 19171884 DOI: 10.1073/pnas.0813045106] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent studies suggest that superoxide dismutase 1 (SOD1)-linked amyotrophic lateral sclerosis results from destabilization and misfolding of mutant forms of this abundant cytosolic enzyme. Here, we have tracked the expression and fate of a misfolding-prone human SOD1, G85R, fused to YFP, in a line of transgenic G85R SOD1-YFP mice. These mice, but not wild-type human SOD1-YFP transgenics, developed lethal paralyzing motor symptoms at 9 months. In situ RNA hybridization of spinal cords revealed predominant expression in motor neurons in spinal cord gray matter in all transgenic animals. Concordantly, G85R SOD-YFP was diffusely fluorescent in motor neurons of animals at 1 and 6 months of age, but at the time of symptoms, punctate aggregates were observed in cell bodies and processes. Biochemical analyses of spinal cord soluble extracts indicated that G85R SOD-YFP behaved as a misfolded monomer at all ages. It became progressively insoluble at 6 and 9 months of age, associated with presence of soluble oligomers observable by gel filtration. Immunoaffinity capture and mass spectrometry revealed association of G85R SOD-YFP, but not WT SOD-YFP, with the cytosolic chaperone Hsc70 at all ages. In addition, 3 Hsp110's, nucleotide exchange factors for Hsp70s, were captured at 6 and 9 months. Despite such chaperone interactions, G85R SOD-YFP formed insoluble inclusions at late times, containing predominantly intermediate filament proteins. We conclude that motor neurons, initially "compensated" to maintain the misfolded protein in a soluble state, become progressively unable to do so.
Collapse
|