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Sheean RK, McKay FC, Cretney E, Bye CR, Perera ND, Tomas D, Weston RA, Scheller KJ, Djouma E, Menon P, Schibeci SD, Marmash N, Yerbury JJ, Nutt SL, Booth DR, Stewart GJ, Kiernan MC, Vucic S, Turner BJ. Association of Regulatory T-Cell Expansion With Progression of Amyotrophic Lateral Sclerosis: A Study of Humans and a Transgenic Mouse Model. JAMA Neurol 2019; 75:681-689. [PMID: 29507931 DOI: 10.1001/jamaneurol.2018.0035] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Importance Neuroinflammation appears to be a key modulator of disease progression in amyotrophic lateral sclerosis (ALS) and thereby a promising therapeutic target. The CD4+Foxp3+ regulatory T-cells (Tregs) infiltrating into the central nervous system suppress neuroinflammation and promote the activation of neuroprotective microglia in mouse models of ALS. To our knowledge, the therapeutic association of host Treg expansion with ALS progression has not been studied in vivo. Objective To assess the role of Tregs in regulating the pathophysiology of ALS in humans and the therapeutic outcome of increasing Treg activity in a mouse model of the disease. Design, Setting, and Participants This prospective multicenter human and animal study was performed in hospitals, outpatient clinics, and research institutes. Clinical and function assessment, as well as immunological studies, were undertaken in 33 patients with sporadic ALS, and results were compared with 38 healthy control participants who were consecutively recruited from the multidisciplinary ALS clinic at Westmead Hospital between February 1, 2013, and December 31, 2014. All data analysis on patients with ALS was undertaken between January 2015 and December 2016. Subsequently, we implemented a novel approach to amplify the endogenous Treg population using peripheral injections of interleukin 2/interleukin 2 monoclonal antibody complexes (IL-2c) in transgenic mice that expressed mutant superoxide dismutase 1 (SOD1), a gene associated with motor neuron degeneration. Main Outcomes and Measures In patients with ALS, Treg levels were determined and then correlated with disease progression. Circulating T-cell populations, motor neuron size, glial cell activation, and T-cell and microglial gene expression in spinal cords were determined in SOD1G93A mice, as well as the association of Treg amplification with disease onset and survival time in mice. Results The cohort of patients with ALS included 24 male patients and 9 female patients (mean [SD] age at assessment, 58.9 [10.9] years). There was an inverse correlation between total Treg levels (including the effector CD45RO+ subset) and rate of disease progression (R = -0.40, P = .002). Expansion of the effector Treg population in the SOD1G93A mice was associated with a significant slowing of disease progression, which was accompanied by an increase in survival time (IL-2c-treated mice: mean [SD], 160.6 [10.8] days; control mice: mean [SD], 144.9 [10.6] days; P = .003). Importantly, Treg expansion was associated with preserved motor neuron soma size and marked suppression of astrocytic and microglial immunoreactivity in the spinal cords of SOD1G93A mice, as well as elevated neurotrophic factor gene expression in spinal cord and peripheral nerves. Conclusions and Relevance These findings establish a neuroprotective effect of Tregs, possibly mediated by suppression of toxic neuroinflammation in the central nervous system. Strategies aimed at enhancing the Treg population and neuroprotective activity from the periphery may prove therapeutically useful for patients with ALS.
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Affiliation(s)
- Rebecca K Sheean
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Fiona C McKay
- Westmead Institute for Medical Research, University of Sydney, Westmead, New South Wales, Australia
| | - Erika Cretney
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Christopher R Bye
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Nirma D Perera
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Doris Tomas
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Richard A Weston
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Karlene J Scheller
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.,Department of Physiology, Anatomy, and Microbiology, La Trobe University, Bundoora, Victoria, Australia
| | - Elvan Djouma
- Department of Physiology, Anatomy, and Microbiology, La Trobe University, Bundoora, Victoria, Australia
| | - Parvathi Menon
- Westmead Hospital, Westmead, New South Wales, Australia.,Western Clinical School, University of Sydney, New South Wales, Australia
| | - Stephen D Schibeci
- Westmead Institute for Medical Research, University of Sydney, Westmead, New South Wales, Australia
| | - Najwa Marmash
- Westmead Hospital, Westmead, New South Wales, Australia
| | - Justin J Yerbury
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, Australia
| | - Stephen L Nutt
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - David R Booth
- Westmead Institute for Medical Research, University of Sydney, Westmead, New South Wales, Australia
| | - Graeme J Stewart
- Westmead Institute for Medical Research, University of Sydney, Westmead, New South Wales, Australia.,Westmead Hospital, Westmead, New South Wales, Australia.,Western Clinical School, University of Sydney, New South Wales, Australia
| | - Mathew C Kiernan
- Brain and Mind Centre, University of Sydney, Camperdown, New South Wales, Australia
| | - Steve Vucic
- Westmead Institute for Medical Research, University of Sydney, Westmead, New South Wales, Australia.,Western Clinical School, University of Sydney, New South Wales, Australia
| | - Bradley J Turner
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
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Perera ND, Sheean RK, Lau CL, Shin YS, Beart PM, Horne MK, Turner BJ. Rilmenidine promotes MTOR-independent autophagy in the mutant SOD1 mouse model of amyotrophic lateral sclerosis without slowing disease progression. Autophagy 2017; 14:534-551. [PMID: 28980850 PMCID: PMC5915012 DOI: 10.1080/15548627.2017.1385674] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 09/15/2017] [Accepted: 09/25/2017] [Indexed: 12/12/2022] Open
Abstract
Macroautophagy/autophagy is the main intracellular catabolic pathway in neurons that eliminates misfolded proteins, aggregates and damaged organelles associated with ageing and neurodegeneration. Autophagy is regulated by both MTOR-dependent and -independent pathways. There is increasing evidence that autophagy is compromised in neurodegenerative disorders, which may contribute to cytoplasmic sequestration of aggregation-prone and toxic proteins in neurons. Genetic or pharmacological modulation of autophagy to promote clearance of misfolded proteins may be a promising therapeutic avenue for these disorders. Here, we demonstrate robust autophagy induction in motor neuronal cells expressing SOD1 or TARDBP/TDP-43 mutants linked to amyotrophic lateral sclerosis (ALS). Treatment of these cells with rilmenidine, an anti-hypertensive agent and imidazoline-1 receptor agonist that induces autophagy, promoted autophagic clearance of mutant SOD1 and efficient mitophagy. Rilmenidine administration to mutant SOD1G93A mice upregulated autophagy and mitophagy in spinal cord, leading to reduced soluble mutant SOD1 levels. Importantly, rilmenidine increased autophagosome abundance in motor neurons of SOD1G93A mice, suggesting a direct action on target cells. Despite robust induction of autophagy in vivo, rilmenidine worsened motor neuron degeneration and symptom progression in SOD1G93A mice. These effects were associated with increased accumulation and aggregation of insoluble and misfolded SOD1 species outside the autophagy pathway, and severe mitochondrial depletion in motor neurons of rilmenidine-treated mice. These findings suggest that rilmenidine treatment may drive disease progression and neurodegeneration in this mouse model due to excessive mitophagy, implying that alternative strategies to beneficially stimulate autophagy are warranted in ALS.
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Affiliation(s)
- Nirma D. Perera
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Rebecca K. Sheean
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Chew L. Lau
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Yea Seul Shin
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Philip M. Beart
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Malcolm K. Horne
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Bradley J. Turner
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
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Lepeta K, Lourenco MV, Schweitzer BC, Martino Adami PV, Banerjee P, Catuara-Solarz S, de La Fuente Revenga M, Guillem AM, Haidar M, Ijomone OM, Nadorp B, Qi L, Perera ND, Refsgaard LK, Reid KM, Sabbar M, Sahoo A, Schaefer N, Sheean RK, Suska A, Verma R, Vicidomini C, Wright D, Zhang XD, Seidenbecher C. Synaptopathies: synaptic dysfunction in neurological disorders - A review from students to students. J Neurochem 2016; 138:785-805. [PMID: 27333343 PMCID: PMC5095804 DOI: 10.1111/jnc.13713] [Citation(s) in RCA: 203] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/03/2016] [Accepted: 06/06/2016] [Indexed: 12/12/2022]
Abstract
Synapses are essential components of neurons and allow information to travel coordinately throughout the nervous system to adjust behavior to environmental stimuli and to control body functions, memories, and emotions. Thus, optimal synaptic communication is required for proper brain physiology, and slight perturbations of synapse function can lead to brain disorders. In fact, increasing evidence has demonstrated the relevance of synapse dysfunction as a major determinant of many neurological diseases. This notion has led to the concept of synaptopathies as brain diseases with synapse defects as shared pathogenic features. In this review, which was initiated at the 13th International Society for Neurochemistry Advanced School, we discuss basic concepts of synapse structure and function, and provide a critical view of how aberrant synapse physiology may contribute to neurodevelopmental disorders (autism, Down syndrome, startle disease, and epilepsy) as well as neurodegenerative disorders (Alzheimer and Parkinson disease). We finally discuss the appropriateness and potential implications of gathering synapse diseases under a single term. Understanding common causes and intrinsic differences in disease-associated synaptic dysfunction could offer novel clues toward synapse-based therapeutic intervention for neurological and neuropsychiatric disorders. In this Review, which was initiated at the 13th International Society for Neurochemistry (ISN) Advanced School, we discuss basic concepts of synapse structure and function, and provide a critical view of how aberrant synapse physiology may contribute to neurodevelopmental (autism, Down syndrome, startle disease, and epilepsy) as well as neurodegenerative disorders (Alzheimer's and Parkinson's diseases), gathered together under the term of synaptopathies. Read the Editorial Highlight for this article on page 783.
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Affiliation(s)
- Katarzyna Lepeta
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Mychael V Lourenco
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Barbara C Schweitzer
- Department for Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology Magdeburg, Magdeburg, Germany
| | - Pamela V Martino Adami
- Laboratory of Amyloidosis and Neurodegeneration, Fundación Instituto Leloir-IIBBA-CONICET, Buenos Aires, Argentina
| | - Priyanjalee Banerjee
- Department of Biochemistry, Institute of Post Graduate Medical Education & Research, Kolkata, West Bengal, India
| | - Silvina Catuara-Solarz
- Systems Biology Program, Cellular and Systems Neurobiology, Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
| | - Mario de La Fuente Revenga
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, United States of America
| | - Alain Marc Guillem
- Laboratorio de Neurotoxicología, Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México D.F. 07000, Mexico
| | - Mouna Haidar
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Omamuyovwi M Ijomone
- Department of Human Anatomy, Cross River University of Technology, Okuku Campus, Cross River, Nigeria
| | - Bettina Nadorp
- The Department of Biological Chemistry, The Edmond and Lily Safra Center for Brain Sciences, The Alexander Grass Center for Bioengineering, The Hebrew University of Jerusalem, Israel
| | - Lin Qi
- Laboratory of Molecular Neuro-Oncology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, United States of America
| | - Nirma D Perera
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Louise K Refsgaard
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Kimberley M Reid
- Department of Pharmacology, UCL School of Pharmacy, 29-39 Brunswick Square, London, WC1N 1AX, UK
| | - Mariam Sabbar
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Arghyadip Sahoo
- Department of Biochemistry, Midnapore Medical College, West Bengal University of Health Sciences, West Bengal, India
| | - Natascha Schaefer
- Institute for Clinical Neurobiology, Julius-Maximilians-University of Wuerzburg, Wuerzburg, Germany
| | - Rebecca K Sheean
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Anna Suska
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Rajkumar Verma
- Department of Neurosciences Uconn Health Center, Farmington, CT, United States of America
| | | | - Dean Wright
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Xing-Ding Zhang
- Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, Houston, TX, United States of America
| | - Constanze Seidenbecher
- Department for Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology Magdeburg, Magdeburg, Germany. .,Center for Behavioral Brain Sciences (CBBS) Magdeburg, Magdeburg, Germany.
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Perera ND, Sheean RK, Crouch PJ, White AR, Horne MK, Turner BJ. Enhancing survival motor neuron expression extends lifespan and attenuates neurodegeneration in mutant TDP-43 mice. Hum Mol Genet 2016; 25:4080-4093. [DOI: 10.1093/hmg/ddw247] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 07/11/2016] [Accepted: 07/14/2016] [Indexed: 12/12/2022] Open
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Sheean RK, Weston RH, Perera ND, D'Amico A, Nutt SL, Turner BJ. Effect of thymic stimulation of CD4+ T cell expansion on disease onset and progression in mutant SOD1 mice. J Neuroinflammation 2015; 12:40. [PMID: 25889790 PMCID: PMC4359394 DOI: 10.1186/s12974-015-0254-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 01/23/2015] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND The peripheral immune system is implicated in modulating microglial activation, neurodegeneration and disease progression in amyotrophic lateral sclerosis (ALS). Specifically, there is reduced thymic function and regulatory T cell (Treg) number in ALS patients and mutant superoxide dismutase 1 (SOD1) mice, while passive transfer of Tregs ameliorates disease in mutant SOD1 mice. Here, we assessed the effects of augmenting endogenous CD4+ T cell number by stimulating the thymus using surgical castration on the phenotype of transgenic SOD1(G93A) mice. METHOD Male SOD1(G93A) mice were castrated or sham operated, and weight loss, disease onset and progression were examined. Thymus atrophy and blood CD4+, CD8+ and CD4+ FoxP3+ T cell numbers were determined by fluorescence activated cell sorting (FACS). Motor neuron counts, glial cell activation and androgen receptor (AR) expression in the spinal cord were investigated using immunohistochemistry and Western blotting. Differences between castrated and sham mice were analysed using an unpaired t test or one-way ANOVA. RESULTS Castration significantly increased thymus weight and total CD4+ T cell numbers in SOD1(G93A) mice, although Tregs levels were not affected. Despite this, disease onset and progression were similar in castrated and sham SOD1(G93A) mice. Castration did not affect motor neuron loss or astrocytic activation in spinal cords of SOD1(G93A) mice; however, microglial activation was reduced, specifically M1 microglia. We also show that AR is principally expressed in spinal motor neurons and progressively downregulated in spinal cords of SOD1(G93A) mice from disease onset which is further enhanced by castration. CONCLUSIONS These results demonstrate that increasing thymic function and CD4+ T cell number by castration confers no clinical benefit in mutant SOD1 mice, which may reflect an inability to stimulate neuroprotective Tregs. Nonetheless, castration decreases M1 microglial activation in the spinal cord without any clinical improvement and motor neuron rescue, in contrast to other approaches to suppress microglia in mutant SOD1 mice. Lastly, diminished AR expression in spinal motor neurons, which links to another motor neuron disorder, spinal bulbar muscular atrophy (SBMA), may contribute to ALS pathogenesis and suggests a common disease pathway in ALS and SBMA mediated by disruption of AR signalling in motor neurons.
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Affiliation(s)
- Rebecca K Sheean
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia.
| | - Richard H Weston
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia.
| | - Nirma D Perera
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia. .,Centre for Neuroscience, University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia.
| | - Angela D'Amico
- The Walter and Eliza Hall Institute of Medical Research, University of Melbourne, 1G Royal Parade, Parkville, Victoria, 3052, Australia.
| | - Stephen L Nutt
- The Walter and Eliza Hall Institute of Medical Research, University of Melbourne, 1G Royal Parade, Parkville, Victoria, 3052, Australia.
| | - Bradley J Turner
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia. .,Centre for Neuroscience, University of Melbourne, 30 Royal Parade, Parkville, Victoria, 3052, Australia.
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Wang TY, Bruggeman KAF, Sheean RK, Turner BJ, Nisbet DR, Parish CL. Characterization of the stability and bio-functionality of tethered proteins on bioengineered scaffolds: implications for stem cell biology and tissue repair. J Biol Chem 2014; 289:15044-51. [PMID: 24700461 DOI: 10.1074/jbc.m113.537381] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Various engineering applications have been utilized to deliver molecules and compounds in both innate and biological settings. In the context of biological applications, the timely delivery of molecules can be critical for cellular and organ function. As such, previous studies have demonstrated the superiority of long-term protein delivery, by way of protein tethering onto bioengineered scaffolds, compared with conventional delivery of soluble protein in vitro and in vivo. Despite such benefits little knowledge exists regarding the stability, release kinetics, longevity, activation of intracellular pathway, and functionality of these proteins over time. By way of example, here we examined the stability, degradation and functionality of a protein, glial-derived neurotrophic factor (GDNF), which is known to influence neuronal survival, differentiation, and neurite morphogenesis. Enzyme-linked immunosorbent assays (ELISA) revealed that GDNF, covalently tethered onto polycaprolactone (PCL) electrospun nanofibrous scaffolds, remained present on the scaffold surface for 120 days, with no evidence of protein leaching or degradation. The tethered GDNF protein remained functional and capable of activating downstream signaling cascades, as revealed by its capacity to phosphorylate intracellular Erk in a neural cell line. Furthermore, immobilization of GDNF protein promoted cell survival and differentiation in culture at both 3 and 7 days, further validating prolonged functionality of the protein, well beyond the minutes to hours timeframe observed for soluble proteins under the same culture conditions. This study provides important evidence of the stability and functionality kinetics of tethered molecules.
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Affiliation(s)
- Ting-Yi Wang
- From the Florey Institute of Neuroscience & Mental Health, The University of Melbourne, Parkville, Australia, 3010 and
| | - Kiara A F Bruggeman
- the Research School of Engineering, The Australian National University, Canberra, Australia, 0200
| | - Rebecca K Sheean
- From the Florey Institute of Neuroscience & Mental Health, The University of Melbourne, Parkville, Australia, 3010 and
| | - Bradley J Turner
- From the Florey Institute of Neuroscience & Mental Health, The University of Melbourne, Parkville, Australia, 3010 and
| | - David R Nisbet
- the Research School of Engineering, The Australian National University, Canberra, Australia, 0200
| | - Clare L Parish
- From the Florey Institute of Neuroscience & Mental Health, The University of Melbourne, Parkville, Australia, 3010 and
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Perera ND, Sheean RK, Scott JW, Kemp BE, Horne MK, Turner BJ. Mutant TDP-43 deregulates AMPK activation by PP2A in ALS models. PLoS One 2014; 9:e90449. [PMID: 24595038 PMCID: PMC3942426 DOI: 10.1371/journal.pone.0090449] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/01/2014] [Indexed: 12/12/2022] Open
Abstract
Bioenergetic abnormalities and metabolic dysfunction occur in amyotrophic lateral sclerosis (ALS) patients and genetic mouse models. However, whether metabolic dysfunction occurs early in ALS pathophysiology linked to different ALS genes remains unclear. Here, we investigated AMP-activated protein kinase (AMPK) activation, which is a key enzyme induced by energy depletion and metabolic stress, in neuronal cells and mouse models expressing mutant superoxide dismutase 1 (SOD1) or TAR DNA binding protein 43 (TDP-43) linked to ALS. AMPK phosphorylation was sharply increased in spinal cords of transgenic SOD1G93A mice at disease onset and accumulated in cytoplasmic granules in motor neurons, but not in pre-symptomatic mice. AMPK phosphorylation also occurred in peripheral tissues, liver and kidney, in SOD1G93A mice at disease onset, demonstrating that AMPK activation occurs late and is not restricted to motor neurons. Conversely, AMPK activity was drastically diminished in spinal cords and brains of presymptomatic and symptomatic transgenic TDP-43A315T mice and motor neuronal cells expressing different TDP-43 mutants. We show that mutant TDP-43 induction of the AMPK phosphatase, protein phosphatase 2A (PP2A), is associated with AMPK inactivation in these ALS models. Furthermore, PP2A inhibition by okadaic acid reversed AMPK inactivation by mutant TDP-43 in neuronal cells. Our results suggest that mutant SOD1 and TDP-43 exert contrasting effects on AMPK activation which may reflect key differences in energy metabolism and neurodegeneration in spinal cords of SOD1G93A and TDP-43A315T mice. While AMPK activation in motor neurons correlates with progression in mutant SOD1-mediated disease, AMPK inactivation mediated by PP2A is associated with mutant TDP-43-linked ALS.
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Affiliation(s)
- Nirma D. Perera
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Victoria, Australia
- Centre for Neuroscience, University of Melbourne, Parkville, Melbourne, Victoria, Australia
| | - Rebecca K. Sheean
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Victoria, Australia
- Centre for Neuroscience, University of Melbourne, Parkville, Melbourne, Victoria, Australia
| | - John W. Scott
- St Vincent's Institute and Department of Medicine, University of Melbourne, Parkville, Melbourne, Australia
| | - Bruce E. Kemp
- St Vincent's Institute and Department of Medicine, University of Melbourne, Parkville, Melbourne, Australia
| | - Malcolm K. Horne
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Victoria, Australia
- Centre for Neuroscience, University of Melbourne, Parkville, Melbourne, Victoria, Australia
| | - Bradley J. Turner
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Victoria, Australia
- Centre for Neuroscience, University of Melbourne, Parkville, Melbourne, Victoria, Australia
- * E-mail:
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