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Keeley O, Coyne AN. Nuclear and degradative functions of the ESCRT-III pathway: implications for neurodegenerative disease. Nucleus 2024; 15:2349085. [PMID: 38700207 PMCID: PMC11073439 DOI: 10.1080/19491034.2024.2349085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Accepted: 04/24/2024] [Indexed: 05/05/2024] Open
Abstract
The ESCRT machinery plays a pivotal role in membrane-remodeling events across multiple cellular processes including nuclear envelope repair and reformation, nuclear pore complex surveillance, endolysosomal trafficking, and neuronal pruning. Alterations in ESCRT-III functionality have been associated with neurodegenerative diseases including Frontotemporal Dementia (FTD), Amyotrophic Lateral Sclerosis (ALS), and Alzheimer's Disease (AD). In addition, mutations in specific ESCRT-III proteins have been identified in FTD/ALS. Thus, understanding how disruptions in the fundamental functions of this pathway and its individual protein components in the human central nervous system (CNS) may offer valuable insights into mechanisms underlying neurodegenerative disease pathogenesis and identification of potential therapeutic targets. In this review, we discuss ESCRT components, dynamics, and functions, with a focus on the ESCRT-III pathway. In addition, we explore the implications of altered ESCRT-III function for neurodegeneration with a primary emphasis on nuclear surveillance and endolysosomal trafficking within the CNS.
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Affiliation(s)
- Olivia Keeley
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Alyssa N. Coyne
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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2
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López-Carbonero JI, García-Toledo I, Fernández-Hernández L, Bascuñana P, Gil-Moreno MJ, Matías-Guiu JA, Corrochano S. In vivo diagnosis of TDP-43 proteinopathies: in search of biomarkers of clinical use. Transl Neurodegener 2024; 13:29. [PMID: 38831349 PMCID: PMC11149336 DOI: 10.1186/s40035-024-00419-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 05/06/2024] [Indexed: 06/05/2024] Open
Abstract
TDP-43 proteinopathies are a heterogeneous group of neurodegenerative disorders that share the presence of aberrant, misfolded and mislocalized deposits of the protein TDP-43, as in the case of amyotrophic lateral sclerosis and some, but not all, pathological variants of frontotemporal dementia. In recent years, many other diseases have been reported to have primary or secondary TDP-43 proteinopathy, such as Alzheimer's disease, Huntington's disease or the recently described limbic-predominant age-related TDP-43 encephalopathy, highlighting the need for new and accurate methods for the early detection of TDP-43 proteinopathy to help on the stratification of patients with overlapping clinical diagnosis. Currently, TDP-43 proteinopathy remains a post-mortem pathologic diagnosis. Although the main aim is to determine the pathologic TDP-43 proteinopathy in the central nervous system (CNS), the ubiquitous expression of TDP-43 in biofluids and cells outside the CNS facilitates the use of other accessible target tissues that might reflect the potential TDP-43 alterations in the brain. In this review, we describe the main developments in the early detection of TDP-43 proteinopathies, and their potential implications on diagnosis and future treatments.
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Affiliation(s)
- Juan I López-Carbonero
- Neurological Disorders Group, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), 28040, Madrid, Spain
| | - Irene García-Toledo
- Neurological Disorders Group, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), 28040, Madrid, Spain
| | - Laura Fernández-Hernández
- Neurological Disorders Group, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), 28040, Madrid, Spain
| | - Pablo Bascuñana
- Neurological Disorders Group, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), 28040, Madrid, Spain
| | - María J Gil-Moreno
- Neurological Disorders Group, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), 28040, Madrid, Spain
| | - Jordi A Matías-Guiu
- Neurological Disorders Group, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), 28040, Madrid, Spain
| | - Silvia Corrochano
- Neurological Disorders Group, Hospital Clínico San Carlos, Instituto de Investigación Sanitaria San Carlos (IdISSC), 28040, Madrid, Spain.
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3
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Turco A, Primiceri E, Chiriacò MS, La Pesa V, Ferrara F, Riva N, Quattrini A, Romano A, Maruccio G. Advancing amyotrophic lateral sclerosis disease diagnosis: A lab-on-chip electrochemical immunosensor for ultra-sensitive TDP-43 protein detection and monitoring in serum patients'. Talanta 2024; 273:125866. [PMID: 38490025 DOI: 10.1016/j.talanta.2024.125866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 12/22/2023] [Accepted: 02/29/2024] [Indexed: 03/17/2024]
Abstract
The global increase in population aging has led to a rise in neurodegenerative diseases (NDs), posing significant challenges to public health. Developing selective and specific biomarkers for early diagnosis and drug development is crucial addressing the growing burden of NDs. In this context, the RNA-binding protein TDP-43 has emerged as a promising biomarker for amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), and TDP-43-associated proteinopathies. However, existing detection methods suffer from limitations such as cost, complexity, and operator dependence. Here, we present a novel electrochemical biosensor integrated into a lab-on-chip (LoC) platform to detect TDP-43. The sensor utilizes electrosynthesized polypyrrole derivatives with carboxylic groups for transducer functionalization, enabling targeted immobilization of TDP-43 antibodies. Differential pulsed voltammetry (DPV) is used for the indirect detection and quantification of TDP-43. The chip exhibits rapid response, good reproducibility, a linear detection range, and sensitivity from 0.01 ng/mL to 25 ng/mL of TDP-43 protein concentration with a LOD = 10 pg/mL. Furthermore, successful TDP-43 detection in complex matrices like serum of ALS patients and healthy individuals demonstrates its potential as a point-of-care diagnostic device. This electrochemical biosensor integrated into a chip offers good sensitivity, rapid response, and robust performance, providing a promising avenue for advancing neurodegenerative disease diagnostics and therapeutic development.
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Affiliation(s)
- Antonio Turco
- CNR Nanotec Institute of Nanotechnology, Via Monteroni, 73100, Lecce, Italy; IRCCS San Raffaele Scientific Institute, Neuropathology Unit, Institute of Experimental Neurology, 20132, Milan, Italy
| | | | | | - Velia La Pesa
- IRCCS San Raffaele Scientific Institute, Neuropathology Unit, Institute of Experimental Neurology, 20132, Milan, Italy
| | - Francesco Ferrara
- CNR Nanotec Institute of Nanotechnology, Via Monteroni, 73100, Lecce, Italy
| | - Nilo Riva
- IRCCS San Raffaele Scientific Institute, Neuropathology Unit, Institute of Experimental Neurology, 20132, Milan, Italy
| | - Angelo Quattrini
- IRCCS San Raffaele Scientific Institute, Neuropathology Unit, Institute of Experimental Neurology, 20132, Milan, Italy
| | - Alessandro Romano
- IRCCS San Raffaele Scientific Institute, Neuropathology Unit, Institute of Experimental Neurology, 20132, Milan, Italy
| | - Giuseppe Maruccio
- CNR Nanotec Institute of Nanotechnology, Via Monteroni, 73100, Lecce, Italy; Omnics Research Group, Department of Mathematics and Physics "Ennio De Giorgi", University of Salento, Via per Monteroni, 73100, Lecce, Italy
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4
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Gomez N, Hsieh C, Li X, Dykstra M, Waksmacki J, Altheim C, Bechar Y, Klim J, Zaepfel B, Rothstein J, Tank EE, Barmada SJ. Counter-regulation of RNA stability by UPF1 and TDP43. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.31.578310. [PMID: 38352350 PMCID: PMC10862862 DOI: 10.1101/2024.01.31.578310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
RNA quality control is crucial for proper regulation of gene expression. Disruption of nonsense mediated mRNA decay (NMD), the primary RNA decay pathway responsible for the degradation of transcripts containing premature termination codons (PTCs), can disrupt development and lead to multiple diseases in humans and other animals. Similarly, therapies targeting NMD may have applications in hematological, neoplastic and neurological disorders. As such, tools capable of accurately quantifying NMD status could be invaluable for investigations of disease pathogenesis and biomarker identification. Toward this end, we assemble, validate, and apply a next-generation sequencing approach (NMDq) for identifying and measuring the abundance of PTC-containing transcripts. After validating NMDq performance and confirming its utility for tracking RNA surveillance, we apply it to determine pathway activity in two neurodegenerative diseases, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) characterized by RNA misprocessing and abnormal RNA stability. Despite the genetic and pathologic evidence implicating dysfunctional RNA metabolism, and NMD in particular, in these conditions, we detected no significant differences in PTC-encoding transcripts in ALS models or disease. Contrary to expectations, overexpression of the master NMD regulator UPF1 had little effect on the clearance of transcripts with PTCs, but rather restored RNA homeostasis through differential use and decay of alternatively poly-adenylated isoforms. Together, these data suggest that canonical NMD is not a significant contributor to ALS/FTD pathogenesis, and that UPF1 promotes neuronal survival by regulating transcripts with abnormally long 3'UTRs.
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5
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Perlegos AE, Durkin J, Belfer SJ, Rodriguez A, Shcherbakova O, Park K, Luong J, Bonini NM, Kayser MS. TDP-43 impairs sleep in Drosophila through Ataxin-2-dependent metabolic disturbance. SCIENCE ADVANCES 2024; 10:eadj4457. [PMID: 38198547 PMCID: PMC10780954 DOI: 10.1126/sciadv.adj4457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 12/12/2023] [Indexed: 01/12/2024]
Abstract
Neurodegenerative diseases such as amyotrophic lateral sclerosis and frontotemporal dementia are associated with substantial sleep disruption, which may accelerate cognitive decline and brain degeneration. Here, we define a role for trans-activation response element (TAR) DNA binding protein 43 (TDP-43), a protein associated with human neurodegenerative disease, in regulating sleep using Drosophila. Expression of TDP-43 severely disrupts sleep, and the sleep deficit is rescued by Atx2 knockdown. Brain RNA sequencing revealed that Atx2 RNA interference regulates transcripts enriched for small-molecule metabolic signaling in TDP-43 brains. Focusing on these Atx2-regulated genes, we identified suppressors of the TDP-43 sleep phenotype enriched for metabolism pathways. Knockdown of Atx2 or treatment with rapamycin attenuated the sleep phenotype and mitigated the disruption of small-molecule glycogen metabolism caused by TDP-43. Our findings provide a connection between toxicity of TDP-43 and sleep disturbances and highlight key aspects of metabolism that interplay with TDP-43 toxicity upon Atx2 rescue.
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Affiliation(s)
- Alexandra E. Perlegos
- Neuroscience Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jaclyn Durkin
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- National Institute of Neurological Disorders & Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Samuel J. Belfer
- Neuroscience Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anyara Rodriguez
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Oksana Shcherbakova
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kristen Park
- Neuroscience Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jenny Luong
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nancy M. Bonini
- Neuroscience Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Matthew S. Kayser
- Department of Psychiatry, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
- Chronobiology Sleep Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
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6
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Rothstein JD, Warlick C, Coyne AN. Highly variable molecular signatures of TDP-43 loss of function are associated with nuclear pore complex injury in a population study of sporadic ALS patient iPSNs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.12.571299. [PMID: 38168312 PMCID: PMC10760028 DOI: 10.1101/2023.12.12.571299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
The nuclear depletion and cytoplasmic aggregation of the RNA binding protein TDP-43 is widely considered a pathological hallmark of Amyotrophic Lateral Sclerosis (ALS) and related neurodegenerative diseases. Recent studies have artificially reduced TDP-43 in wildtype human neurons to replicate loss of function associated events. Although this prior work has defined a number of gene expression and mRNA splicing changes that occur in a TDP-43 dependent manner, it is unclear how these alterations relate to authentic ALS where TDP-43 is not depleted from the cell but miscompartmentalized to variable extents. Here, in this population study, we generate ~30,000 qRT-PCR data points spanning 20 genes in induced pluripotent stem cell (iPSC) derived neurons (iPSNs) from >150 control, C9orf72 ALS/FTD, and sALS patients to examine molecular signatures of TDP-43 dysfunction. This data set defines a time dependent and variable profile of individual molecular hallmarks of TDP-43 loss of function within and amongst individual patient lines. Importantly, nearly identical changes are observed in postmortem CNS tissues obtained from a subset of patients whose iPSNs were examined. Notably, these studies provide evidence that induction of nuclear pore complex (NPC) injury via reduction of the transmembrane Nup POM121 in wildtype iPSNs is sufficient to phenocopy disease associated signatured of TDP-43 loss of function thereby directly linking NPC integrity to TDP-43 loss of function. Therapeutically, we demonstrate that the expression of all mRNA species associated with TDP-43 loss of function can be restored in sALS iPSNs via two independent methods to repair NPC injury. Collectively, this data 1) represents a substantial resource for the community to examine TDP-43 loss of function events in authentic sALS patient iPSNs, 2) demonstrates that patient derived iPSNs can accurately reflect actual TDP-43 associated alterations in patient brain, and 3) that targeting NPC injury events can be preclinically and reliably accomplished in an iPSN based platform of a sporadic disease.
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Affiliation(s)
- Jeffrey D. Rothstein
- Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore MD 21205
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore MD 21205
| | - Caroline Warlick
- Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore MD 21205
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore MD 21205
| | - Alyssa N. Coyne
- Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore MD 21205
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore MD 21205
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7
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Pisciottani A, Croci L, Lauria F, Marullo C, Savino E, Ambrosi A, Podini P, Marchioretto M, Casoni F, Cremona O, Taverna S, Quattrini A, Cioni JM, Viero G, Codazzi F, Consalez GG. Neuronal models of TDP-43 proteinopathy display reduced axonal translation, increased oxidative stress, and defective exocytosis. Front Cell Neurosci 2023; 17:1253543. [PMID: 38026702 PMCID: PMC10679756 DOI: 10.3389/fncel.2023.1253543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 10/13/2023] [Indexed: 12/01/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive, lethal neurodegenerative disease mostly affecting people around 50-60 years of age. TDP-43, an RNA-binding protein involved in pre-mRNA splicing and controlling mRNA stability and translation, forms neuronal cytoplasmic inclusions in an overwhelming majority of ALS patients, a phenomenon referred to as TDP-43 proteinopathy. These cytoplasmic aggregates disrupt mRNA transport and localization. The axon, like dendrites, is a site of mRNA translation, permitting the local synthesis of selected proteins. This is especially relevant in upper and lower motor neurons, whose axon spans long distances, likely accentuating their susceptibility to ALS-related noxae. In this work we have generated and characterized two cellular models, consisting of virtually pure populations of primary mouse cortical neurons expressing a human TDP-43 fusion protein, wt or carrying an ALS mutation. Both forms facilitate cytoplasmic aggregate formation, unlike the corresponding native proteins, giving rise to bona fide primary culture models of TDP-43 proteinopathy. Neurons expressing TDP-43 fusion proteins exhibit a global impairment in axonal protein synthesis, an increase in oxidative stress, and defects in presynaptic function and electrical activity. These changes correlate with deregulation of axonal levels of polysome-engaged mRNAs playing relevant roles in the same processes. Our data support the emerging notion that deregulation of mRNA metabolism and of axonal mRNA transport may trigger the dying-back neuropathy that initiates motor neuron degeneration in ALS.
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Affiliation(s)
- Alessandra Pisciottani
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Laura Croci
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Fabio Lauria
- Institute of Biophysics, CNR Unit at Trento, Povo, Italy
| | - Chiara Marullo
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Elisa Savino
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Alessandro Ambrosi
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Paola Podini
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Filippo Casoni
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Ottavio Cremona
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
| | - Stefano Taverna
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Angelo Quattrini
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Jean-Michel Cioni
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | | | - Franca Codazzi
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - G. Giacomo Consalez
- Faculty of Medicine and Surgery, Università Vita-Salute San Raffaele, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
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8
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Tanaka Y, Ito SI, Honma Y, Hasegawa M, Kametani F, Suzuki G, Kozuma L, Takeya K, Eto M. Dysregulation of the progranulin-driven autophagy-lysosomal pathway mediates secretion of the nuclear protein TDP-43. J Biol Chem 2023; 299:105272. [PMID: 37739033 PMCID: PMC10641265 DOI: 10.1016/j.jbc.2023.105272] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 09/04/2023] [Accepted: 09/12/2023] [Indexed: 09/24/2023] Open
Abstract
The cytoplasmic accumulation of the nuclear protein transactive response DNA-binding protein 43 kDa (TDP-43) has been linked to the progression of amyotrophic lateral sclerosis and frontotemporal lobar degeneration. TDP-43 secreted into the extracellular space has been suggested to contribute to the cell-to-cell spread of the cytoplasmic accumulation of TDP-43 throughout the brain; however, the underlying mechanisms remain unknown. We herein demonstrated that the secretion of TDP-43 was stimulated by the inhibition of the autophagy-lysosomal pathway driven by progranulin (PGRN), a causal protein of frontotemporal lobar degeneration. Among modulators of autophagy, only vacuolar-ATPase inhibitors, such as bafilomycin A1 (Baf), increased the levels of the full-length and cleaved forms of TDP-43 and the autophagosome marker LC3-II (microtubule-associated proteins 1A/1B light chain 3B) in extracellular vesicle fractions prepared from the culture media of HeLa, SH-SY5Y, or NSC-34 cells, whereas vacuolin-1, MG132, chloroquine, rapamycin, and serum starvation did not. The C-terminal fragment of TDP-43 was required for Baf-induced TDP-43 secretion. The Baf treatment induced the translocation of the aggregate-prone GFP-tagged C-terminal fragment of TDP-43 and mCherry-tagged LC3 to the plasma membrane. The Baf-induced secretion of TDP-43 was attenuated in autophagy-deficient ATG16L1 knockout HeLa cells. The knockdown of PGRN induced the secretion of cleaved TDP-43 in an autophagy-dependent manner in HeLa cells. The KO of PGRN in mouse embryonic fibroblasts increased the secretion of the cleaved forms of TDP-43 and LC3-II. The treatment inducing TDP-43 secretion increased the nuclear translocation of GFP-tagged transcription factor EB, a master regulator of the autophagy-lysosomal pathway in SH-SY5Y cells. These results suggest that the secretion of TDP-43 is promoted by dysregulation of the PGRN-driven autophagy-lysosomal pathway.
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Affiliation(s)
- Yoshinori Tanaka
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, Imabari-shi, Ehime, Japan.
| | - Shun-Ichi Ito
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, Imabari-shi, Ehime, Japan
| | - Yuki Honma
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, Imabari-shi, Ehime, Japan
| | - Masato Hasegawa
- Department of Brain and Neurosciences, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Fuyuki Kametani
- Department of Brain and Neurosciences, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Genjiro Suzuki
- Department of Brain and Neurosciences, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Lina Kozuma
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, Imabari-shi, Ehime, Japan
| | - Kosuke Takeya
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, Imabari-shi, Ehime, Japan
| | - Masumi Eto
- Biochemistry Unit, Faculty of Veterinary Medicine, Okayama University of Science, Imabari-shi, Ehime, Japan
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9
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Genin EC, Abou-Ali M, Paquis-Flucklinger V. Mitochondria, a Key Target in Amyotrophic Lateral Sclerosis Pathogenesis. Genes (Basel) 2023; 14:1981. [PMID: 38002924 PMCID: PMC10671245 DOI: 10.3390/genes14111981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 10/19/2023] [Accepted: 10/21/2023] [Indexed: 11/26/2023] Open
Abstract
Mitochondrial dysfunction occurs in numerous neurodegenerative diseases, particularly amyotrophic lateral sclerosis (ALS), where it contributes to motor neuron (MN) death. Of all the factors involved in ALS, mitochondria have been considered as a major player, as secondary mitochondrial dysfunction has been found in various models and patients. Abnormal mitochondrial morphology, defects in mitochondrial dynamics, altered activities of respiratory chain enzymes and increased production of reactive oxygen species have been described. Moreover, the identification of CHCHD10 variants in ALS patients was the first genetic evidence that a mitochondrial defect may be a primary cause of MN damage and directly links mitochondrial dysfunction to the pathogenesis of ALS. In this review, we focus on the role of mitochondria in ALS and highlight the pathogenic variants of ALS genes associated with impaired mitochondrial functions. The multiple pathways demonstrated in ALS pathogenesis suggest that all converge to a common endpoint leading to MN loss. This may explain the disappointing results obtained with treatments targeting a single pathological process. Fighting against mitochondrial dysfunction appears to be a promising avenue for developing combined therapies in the future.
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Affiliation(s)
- Emmanuelle C. Genin
- Institute for Research on Cancer and Aging, Nice (IRCAN), Université Côte d’Azur, Inserm U1081, CNRS UMR7284, Centre Hospitalier Universitaire (CHU) de Nice, 06200 Nice, France; (M.A.-A.); (V.P.-F.)
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10
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Necarsulmer JC, Simon JM, Evangelista BA, Chen Y, Tian X, Nafees S, Marquez AB, Jiang H, Wang P, Ajit D, Nikolova VD, Harper KM, Ezzell JA, Lin FC, Beltran AS, Moy SS, Cohen TJ. RNA-binding deficient TDP-43 drives cognitive decline in a mouse model of TDP-43 proteinopathy. eLife 2023; 12:RP85921. [PMID: 37819053 PMCID: PMC10567115 DOI: 10.7554/elife.85921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023] Open
Abstract
TDP-43 proteinopathies including frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative disorders characterized by aggregation and mislocalization of the nucleic acid-binding protein TDP-43 and subsequent neuronal dysfunction. Here, we developed endogenous models of sporadic TDP-43 proteinopathy based on the principle that disease-associated TDP-43 acetylation at lysine 145 (K145) alters TDP-43 conformation, impairs RNA-binding capacity, and induces downstream mis-regulation of target genes. Expression of acetylation-mimic TDP-43K145Q resulted in stress-induced nuclear TDP-43 foci and loss of TDP-43 function in primary mouse and human-induced pluripotent stem cell (hiPSC)-derived cortical neurons. Mice harboring the TDP-43K145Q mutation recapitulated key hallmarks of FTLD, including progressive TDP-43 phosphorylation and insolubility, TDP-43 mis-localization, transcriptomic and splicing alterations, and cognitive dysfunction. Our study supports a model in which TDP-43 acetylation drives neuronal dysfunction and cognitive decline through aberrant splicing and transcription of critical genes that regulate synaptic plasticity and stress response signaling. The neurodegenerative cascade initiated by TDP-43 acetylation recapitulates many aspects of human FTLD and provides a new paradigm to further interrogate TDP-43 proteinopathies.
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Affiliation(s)
- Julie C Necarsulmer
- Department of Cell Biology and Physiology, University of North CarolinaChapel HillUnited States
- Department of Neurology, University of North CarolinaChapel HillUnited States
| | - Jeremy M Simon
- UNC Neuroscience Center, University of North CarolinaChapel HillUnited States
- Carolina Institute for Developmental Disabilities, University of North CarolinaChapel HillUnited States
- Department of Genetics, University of North CarolinaChapel HillUnited States
| | - Baggio A Evangelista
- Department of Cell Biology and Physiology, University of North CarolinaChapel HillUnited States
- Department of Neurology, University of North CarolinaChapel HillUnited States
| | - Youjun Chen
- Department of Neurology, University of North CarolinaChapel HillUnited States
| | - Xu Tian
- Department of Neurology, University of North CarolinaChapel HillUnited States
| | - Sara Nafees
- Department of Neurology, University of North CarolinaChapel HillUnited States
| | - Ariana B Marquez
- Human Pluripotent Stem Cell Core, University of North CarolinaChapel HillUnited States
| | - Huijun Jiang
- Department of Biostatistics, University of North CarolinaChapel HillUnited States
| | - Ping Wang
- Department of Neurology, University of North CarolinaChapel HillUnited States
| | - Deepa Ajit
- Department of Neurology, University of North CarolinaChapel HillUnited States
| | - Viktoriya D Nikolova
- Carolina Institute for Developmental Disabilities, University of North CarolinaChapel HillUnited States
- Department of Psychiatry, The University of North CarolinaChapel HillUnited States
| | - Kathryn M Harper
- Carolina Institute for Developmental Disabilities, University of North CarolinaChapel HillUnited States
- Department of Psychiatry, The University of North CarolinaChapel HillUnited States
| | - J Ashley Ezzell
- Department of Cell Biology & Physiology, Histology Research Core Facility, University of North CarolinaChapel HillUnited States
| | - Feng-Chang Lin
- Department of Biostatistics, University of North CarolinaChapel HillUnited States
| | - Adriana S Beltran
- Department of Genetics, University of North CarolinaChapel HillUnited States
- Human Pluripotent Stem Cell Core, University of North CarolinaChapel HillUnited States
- Department of Pharmacology, University of North CarolinaChapel HillUnited States
| | - Sheryl S Moy
- Carolina Institute for Developmental Disabilities, University of North CarolinaChapel HillUnited States
- Department of Psychiatry, The University of North CarolinaChapel HillUnited States
| | - Todd J Cohen
- Department of Cell Biology and Physiology, University of North CarolinaChapel HillUnited States
- Department of Neurology, University of North CarolinaChapel HillUnited States
- UNC Neuroscience Center, University of North CarolinaChapel HillUnited States
- Department of Biochemistry and Biophysics, University of North CarolinaChapel HillUnited States
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11
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Tomé SO, Tsaka G, Ronisz A, Ospitalieri S, Gawor K, Gomes LA, Otto M, von Arnim CAF, Van Damme P, Van Den Bosch L, Ghebremedhin E, Laureyssen C, Sleegers K, Vandenberghe R, Rousseau F, Schymkowitz J, Thal DR. TDP-43 pathology is associated with increased tau burdens and seeding. Mol Neurodegener 2023; 18:71. [PMID: 37777806 PMCID: PMC10544192 DOI: 10.1186/s13024-023-00653-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 09/04/2023] [Indexed: 10/02/2023] Open
Abstract
BACKGROUND Most Alzheimer's Disease (AD) cases also exhibit limbic predominant age-related TDP-43 encephalopathy neuropathological changes (LATE-NC), besides amyloid-β plaques and neurofibrillary tangles (NFTs) containing hyperphosphorylated tau (p-tau). LATE-NC is characterized by cytoplasmic aggregates positive for pathological TDP-43 and is associated with more severe clinical outcomes in AD, compared to AD cases lacking TDP-43 pathology TDP-43: AD(LATE-NC-). Accumulating evidence suggests that TDP-43 and p-tau interact and exhibit pathological synergy during AD pathogenesis. However, it is not yet fully understood how the presence of TDP-43 affects p-tau aggregation in symptomatic AD. METHODS In this study, we investigated the impact of TDP-43 proteinopathy on p-tau pathology with different approaches: histologically, in a human post-mortem cohort (n = 98), as well as functionally using a tau biosensor cell line and TDP-43A315T transgenic mice. RESULTS We found that AD cases with comorbid LATE-NC, AD(LATE-NC+), have increased burdens of pretangles and/or NFTs as well as increased brain levels of p-tau199, compared to AD(LATE-NC-) cases and controls. The burden of TDP-43 pathology was also correlated with the Braak NFT stages. A tau biosensor cell line treated with sarkosyl-insoluble, brain-derived homogenates from AD(LATE-NC+) cases displayed exacerbated p-tau seeding, compared to control and AD(LATE-NC-)-treated cells. Consistently, TDP-43A315T mice injected with AD(LATE-NC+)-derived extracts also exhibited a more severe hippocampal seeding, compared to the remaining experimental groups, albeit no TDP-43 aggregation was observed. CONCLUSIONS Our findings extend the current knowledge by supporting a functional synergy between TDP-43 and p-tau. We further demonstrate that TDP-43 pathology worsens p-tau aggregation in an indirect manner and increases its seeding potential, probably by increasing p-tau levels. This may ultimately contribute to tau-driven neurotoxicity and cell death. Because most AD cases present with comorbid LATE-NC, this study has an impact on the understanding of TDP-43 and tau pathogenesis in AD and LATE, which account for the majority of dementia cases worldwide. Moreover, it highlights the need for the development of a biomarker that detects TDP-43 during life, in order to properly stratify AD and LATE patients.
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Affiliation(s)
- Sandra O Tomé
- Laboratory of Neuropathology - Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.
- Leuven Brain Institute, KU Leuven, Leuven, Belgium.
| | - Grigoria Tsaka
- Laboratory of Neuropathology - Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Switch Laboratory, VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Alicja Ronisz
- Laboratory of Neuropathology - Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Simona Ospitalieri
- Laboratory of Neuropathology - Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Klara Gawor
- Laboratory of Neuropathology - Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Luis Aragão Gomes
- Laboratory of Neuropathology - Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Markus Otto
- Department of Neurology, University of Ulm, Ulm, Germany
- Department of Neurology, University of Halle, Halle, Germany
| | - Christine A F von Arnim
- Department of Neurology, University of Ulm, Ulm, Germany
- Department of Geriatrics, University Medical Center Göttingen, Göttingen, Germany
| | - Philip Van Damme
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Laboratory for Neurobiology - VIB-KU Leuven, Leuven, Belgium
- Department of Neurology, UZ Leuven, Leuven, Belgium
| | - Ludo Van Den Bosch
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Laboratory for Neurobiology - VIB-KU Leuven, Leuven, Belgium
| | - Estifanos Ghebremedhin
- Institute for Clinical Neuroanatomy - Johann Wolfgang Goethe University, Frankfurt Am Main, Germany
| | - Celeste Laureyssen
- Complex Genetics of Alzheimer's Disease Group, VIB-University of Antwerp Center for Molecular Neurology, Antwerp, Belgium
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Kristel Sleegers
- Complex Genetics of Alzheimer's Disease Group, VIB-University of Antwerp Center for Molecular Neurology, Antwerp, Belgium
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Rik Vandenberghe
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Department of Neurology, UZ Leuven, Leuven, Belgium
- Laboratory of Experimental Neurology - Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Frederic Rousseau
- Switch Laboratory, VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Joost Schymkowitz
- Switch Laboratory, VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Dietmar Rudolf Thal
- Laboratory of Neuropathology - Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Department of Pathology, UZ Leuven, Leuven, Belgium
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12
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Cao MC, Ryan B, Wu J, Curtis MA, Faull RLM, Dragunow M, Scotter EL. A panel of TDP-43-regulated splicing events verifies loss of TDP-43 function in amyotrophic lateral sclerosis brain tissue. Neurobiol Dis 2023; 185:106245. [PMID: 37527763 DOI: 10.1016/j.nbd.2023.106245] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 07/13/2023] [Accepted: 07/28/2023] [Indexed: 08/03/2023] Open
Abstract
TDP-43 dysfunction is a molecular hallmark of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). A major hypothesis of TDP-43 dysfunction in disease is the loss of normal nuclear function, resulting in impaired RNA regulation and the emergence of cryptic exons. Cryptic exons and differential exon usage are emerging as promising markers of lost TDP-43 function in addition to revealing biological pathways involved in neurodegeneration in ALS/FTD. In this brief report, we identified markers of TDP-43 loss of function by depleting TARDBP from post-mortem human brain pericytes, a manipulable in vitro primary human brain cell model, and identifying differential exon usage events with bulk RNA-sequencing analysis. We present these data in an interactive database (https://www.scotterlab.auckland.ac.nz/research-themes/tdp43-lof-db-v2/) together with seven other TDP-43-depletion datasets we meta-analysed previously, for user analysis of differential expression and splicing signatures. Differential exon usage events that were validated by qPCR were then compiled into a 'differential exon usage panel' with other well-established TDP-43 loss-of-function exon markers. This differential exon usage panel was investigated in ALS and control motor cortex tissue to verify whether, and to what extent, TDP-43 loss of function occurs in ALS. We find that profiles of TDP-43-regulated cryptic exons, changed exon usage and changed 3' UTR usage discriminate ALS brain tissue from controls, verifying that TDP-43 loss of function occurs in ALS. We propose that TDP-43-regulated splicing events that occur in brain tissue will have promise as predictors of disease.
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Affiliation(s)
- Maize C Cao
- Department of Pharmacology, University of Auckland, New Zealand; Centre for Brain Research, University of Auckland, New Zealand.
| | - Brigid Ryan
- Department of Anatomy and Medical Imaging, University of Auckland, New Zealand; Centre for Brain Research, University of Auckland, New Zealand.
| | - Jane Wu
- Department of Anatomy and Medical Imaging, University of Auckland, New Zealand; Centre for Brain Research, University of Auckland, New Zealand.
| | - Maurice A Curtis
- Department of Anatomy and Medical Imaging, University of Auckland, New Zealand; Centre for Brain Research, University of Auckland, New Zealand.
| | - Richard L M Faull
- Department of Anatomy and Medical Imaging, University of Auckland, New Zealand; Centre for Brain Research, University of Auckland, New Zealand.
| | - Mike Dragunow
- Department of Pharmacology, University of Auckland, New Zealand; Centre for Brain Research, University of Auckland, New Zealand.
| | - Emma L Scotter
- School of Biological Sciences, University of Auckland, New Zealand; Centre for Brain Research, University of Auckland, New Zealand.
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13
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Ramachandran S, Grozdanov V, Leins B, Kandler K, Witzel S, Mulaw M, Ludolph AC, Weishaupt JH, Danzer KM. Low T-cell reactivity to TDP-43 peptides in ALS. Front Immunol 2023; 14:1193507. [PMID: 37545536 PMCID: PMC10401033 DOI: 10.3389/fimmu.2023.1193507] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 07/03/2023] [Indexed: 08/08/2023] Open
Abstract
Background Dysregulation of the immune system in amyotrophic lateral sclerosis (ALS) includes changes in T-cells composition and infiltration of T cells in the brain and spinal cord. Recent studies have shown that cytotoxic T cells can directly induce motor neuron death in a mouse model of ALS and that T cells from ALS patients are cytotoxic to iPSC-derived motor neurons from ALS patients. Furthermore, a clonal expansion to unknown epitope(s) was recently found in familial ALS and increased peripheral and intrathecal activation of cytotoxic CD8+ T cells in sporadic ALS. Results Here, we show an increased activation of peripheral T cells from patients with sporadic ALS by IL-2 treatment, suggesting an increase of antigen-experienced T cells in ALS blood. However, a putative antigen for T-cell activation in ALS has not yet been identified. Therefore, we investigated if peptides derived from TDP-43, a key protein in ALS pathogenesis, can act as epitopes for antigen-mediated activation of human T cells by ELISPOT and flow cytometry. We found that TDP-43 peptides induced only a weak MHCI or MHCII-restricted activation of both naïve and antigen-experienced T cells from healthy controls and ALS patients. Interestingly, we found less activation in T cells from ALS patients to TDP-43 and control stimuli. Furthermore, we found no change in the levels of naturally occurring auto-antibodies against full-length TDP-43 in ALS. Conclusion Our data suggests a general increase in antigen-experienced T cells in ALS blood, measured by in-vitro culture with IL-2 for 14 days. Furthermore, it suggests that TDP-43 is a weak autoantigen.
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Affiliation(s)
| | | | - Bianca Leins
- Neurology, University Clinic, University of Ulm, Ulm, Germany
| | | | - Simon Witzel
- Neurology, University Clinic, University of Ulm, Ulm, Germany
| | - Medhanie Mulaw
- Institute of Experimental Cancer Research, Medical Faculty, University of Ulm, Ulm, Germany
| | - Albert C. Ludolph
- Neurology, University Clinic, University of Ulm, Ulm, Germany
- German Center for Neurodegenerative Diseases (DZNE), Ulm, Germany
| | - Jochen H. Weishaupt
- Neurology, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Karin M. Danzer
- Neurology, University Clinic, University of Ulm, Ulm, Germany
- German Center for Neurodegenerative Diseases (DZNE), Ulm, Germany
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14
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Afroz T, Chevalier E, Audrain M, Dumayne C, Ziehm T, Moser R, Egesipe AL, Mottier L, Ratnam M, Neumann M, Havas D, Ollier R, Piorkowska K, Chauhan M, Silva AB, Thapa S, Stöhr J, Bavdek A, Eligert V, Adolfsson O, Nelson PT, Porta S, Lee VMY, Pfeifer A, Kosco-Vilbois M, Seredenina T. Immunotherapy targeting the C-terminal domain of TDP-43 decreases neuropathology and confers neuroprotection in mouse models of ALS/FTD. Neurobiol Dis 2023; 179:106050. [PMID: 36809847 DOI: 10.1016/j.nbd.2023.106050] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/10/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
Effective therapies are urgently needed to safely target TDP-43 pathology as it is closely associated with the onset and development of devastating diseases such as frontotemporal lobar degeneration with TDP-43 pathology (FTLD-TDP) and amyotrophic lateral sclerosis (ALS). In addition, TDP-43 pathology is present as a co-pathology in other neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Our approach is to develop a TDP-43-specific immunotherapy that exploits Fc gamma-mediated removal mechanisms to limit neuronal damage while maintaining physiological TDP-43 function. Thus, using both in vitro mechanistic studies in conjunction with the rNLS8 and CamKIIa inoculation mouse models of TDP-43 proteinopathy, we identified the key targeting domain in TDP-43 to accomplish these therapeutic objectives. Targeting the C-terminal domain of TDP-43 but not the RNA recognition motifs (RRM) reduces TDP-43 pathology and avoids neuronal loss in vivo. We demonstrate that this rescue is dependent on Fc receptor-mediated immune complex uptake by microglia. Furthermore, monoclonal antibody (mAb) treatment enhances phagocytic capacity of ALS patient-derived microglia, providing a mechanism to restore the compromised phagocytic function in ALS and FTD patients. Importantly, these beneficial effects are achieved while preserving physiological TDP-43 activity. Our findings demonstrate that a mAb targeting the C-terminal domain of TDP-43 limits pathology and neurotoxicity, enabling clearance of misfolded TDP-43 through microglia engagement, and supporting the clinical strategy to target TDP-43 by immunotherapy. SIGNIFICANCE STATEMENT: TDP-43 pathology is associated with various devastating neurodegenerative disorders with high unmet medical needs such as frontotemporal dementia (FTD), amyotrophic lateral sclerosis (ALS) and Alzheimer's disease. Thus, safely and effectively targeting pathological TDP-43 represents a key paradigm for biotechnical research as currently there is little in clinical development. After years of research, we have determined that targeting the C-terminal domain of TDP-43 rescues multiple patho-mechanisms involved in disease progression in two animal models of FTD/ALS. In parallel, importantly, our studies establish that this approach does not alter the physiological functions of this ubiquitously expressed and indispensable protein. Together, our findings substantially contribute to the understanding of TDP-43 pathobiology and support the prioritization for clinical testing of immunotherapy approaches targeting TDP-43.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Manuela Neumann
- Department of Neuropathology, University of Tübingen, Tübingen, Germany; DZNE, German Center for Neurodegenerative Diseases, Tübingen, Germany
| | | | | | | | | | | | | | | | | | | | | | | | - Sílvia Porta
- Center for Neurodegenerative Disease Research (CNDR), Institute on Aging, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Virginia M-Y Lee
- Center for Neurodegenerative Disease Research (CNDR), Institute on Aging, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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15
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Doke AA, Jha SK. Shapeshifter TDP-43: Molecular mechanism of structural polymorphism, aggregation, phase separation and their modulators. Biophys Chem 2023; 295:106972. [PMID: 36812677 DOI: 10.1016/j.bpc.2023.106972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/09/2023] [Accepted: 02/12/2023] [Indexed: 02/17/2023]
Abstract
TDP-43 is a nucleic acid-binding protein that performs physiologically essential functions and is known to undergo phase separation and aggregation during stress. Initial observations have shown that TDP-43 forms heterogeneous assemblies, including monomer, dimer, oligomers, aggregates, phase-separated assemblies, etc. However, the significance of each assembly of TDP-43 concerning its function, phase separation, and aggregation is poorly known. Furthermore, how different assemblies of TDP-43 are related to each other is unclear. In this review, we focus on the various assemblies of TDP-43 and discuss the plausible origin of the structural heterogeneity of TDP-43. TDP-43 is involved in multiple physiological processes like phase separation, aggregation, prion-like seeding, and performing physiological functions. However, the molecular mechanism behind the physiological process performed by TDP-43 is not well understood. The current review discusses the plausible molecular mechanism of phase separation, aggregation, and prion-like propagation of TDP-43.
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Affiliation(s)
- Abhilasha A Doke
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Santosh Kumar Jha
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India.
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16
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McMillan M, Gomez N, Hsieh C, Bekier M, Li X, Miguez R, Tank EMH, Barmada SJ. RNA methylation influences TDP43 binding and disease pathogenesis in models of amyotrophic lateral sclerosis and frontotemporal dementia. Mol Cell 2023; 83:219-236.e7. [PMID: 36634675 PMCID: PMC9899051 DOI: 10.1016/j.molcel.2022.12.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 11/14/2022] [Accepted: 12/16/2022] [Indexed: 01/13/2023]
Abstract
RNA methylation at adenosine N6 (m6A) is one of the most common RNA modifications, impacting RNA stability, transport, and translation. Previous studies uncovered RNA destabilization in amyotrophic lateral sclerosis (ALS) models in association with accumulation of the RNA-binding protein TDP43. Here, we show that TDP43 recognizes m6A RNA and that RNA methylation is critical for both TDP43 binding and autoregulation. We also observed extensive RNA hypermethylation in ALS spinal cord, corresponding to methylated TDP43 substrates. Emphasizing the importance of m6A for TDP43 binding and function, we identified several m6A factors that enhance or suppress TDP43-mediated toxicity via single-cell CRISPR-Cas9 in primary neurons. The most promising modifier-the canonical m6A reader YTHDF2-accumulated within ALS spinal neurons, and its knockdown prolonged the survival of human neurons carrying ALS-associated mutations. Collectively, these data show that m6A modifications modulate RNA binding by TDP43 and that m6A is pivotal for TDP43-related neurodegeneration in ALS.
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Affiliation(s)
- Michael McMillan
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Nicolas Gomez
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109, USA; Medical Scientist Training Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Caroline Hsieh
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Michael Bekier
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Xingli Li
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Roberto Miguez
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Elizabeth M H Tank
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sami J Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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17
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Sirtuin-1 sensitive lysine-136 acetylation drives phase separation and pathological aggregation of TDP-43. Nat Commun 2022; 13:1223. [PMID: 35264561 PMCID: PMC8907366 DOI: 10.1038/s41467-022-28822-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 01/11/2022] [Indexed: 12/12/2022] Open
Abstract
Trans-activation response DNA-binding protein of 43 kDa (TDP-43) regulates RNA processing and forms neuropathological aggregates in patients with amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Investigating TDP-43 post-translational modifications, we discovered that K84 acetylation reduced nuclear import whereas K136 acetylation impaired RNA binding and splicing capabilities of TDP-43. Such failure of RNA interaction triggered TDP-43 phase separation mediated by the C-terminal low complexity domain, leading to the formation of insoluble aggregates with pathologically phosphorylated and ubiquitinated TDP-43. Introduction of acetyl-lysine at the identified sites via amber suppression confirmed the results from site-directed mutagenesis. K84-acetylated TDP-43 showed cytoplasmic mislocalization, and the aggregation propensity of K136-acetylated TDP-43 was confirmed. We generated antibodies selective for TDP-43 acetylated at these lysines, and found that sirtuin-1 can potently deacetylate K136-acetylated TDP-43 and reduce its aggregation propensity. Thus, distinct lysine acetylations modulate nuclear import, RNA binding and phase separation of TDP-43, suggesting regulatory mechanisms for TDP-43 pathogenesis.
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18
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TDP-43 Cytoplasmic Translocation in the Skin Fibroblasts of ALS Patients. Cells 2022; 11:cells11020209. [PMID: 35053327 PMCID: PMC8773870 DOI: 10.3390/cells11020209] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/23/2021] [Accepted: 01/04/2022] [Indexed: 12/10/2022] Open
Abstract
Diagnosis of ALS is based on clinical symptoms when motoneuron degeneration is significant. Therefore, new approaches for early diagnosis are needed. We aimed to assess if alterations in appearance and cellular localization of cutaneous TDP-43 may represent a biomarker for ALS. Skin biopsies from 64 subjects were analyzed: 44 ALS patients, 10 healthy controls (HC) and 10 neurological controls (NC) (Parkinson’s disease and multiple sclerosis). TDP-43 immunoreactivity in epidermis and dermis was analyzed, as well as the percentage of cells with TDP-43 cytoplasmic localization. We detected a higher amount of TDP-43 in epidermis (p < 0.001) and in both layers of dermis (p < 0.001), as well as a higher percentage of TDP-43 cytoplasmic positive cells (p < 0.001) in the ALS group compared to HC and NC groups. Dermal cells containing TDP-43 were fibroblasts as identified by co-labeling against vimentin. ROC analyses (AUC 0.867, p < 0.001; CI 95% 0.800–0.935) showed that detection of 24.1% cells with cytoplasmic TDP-43 positivity in the dermis had 85% sensitivity and 80% specificity for detecting ALS. We have identified significantly increased TDP-43 levels in epidermis and in the cytoplasm of dermal cells of ALS patients. Our findings provide support for the use of TDP-43 in skin biopsies as a potential biomarker.
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19
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Corbet GA, Wheeler JR, Parker R, Weskamp K. TDP43 ribonucleoprotein granules: physiologic function to pathologic aggregates. RNA Biol 2021; 18:128-138. [PMID: 34412568 DOI: 10.1080/15476286.2021.1963099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Ribonucleoprotein (RNP) assemblies are ubiquitous in eukaryotic cells and have functions throughout RNA transcription, splicing, and stability. Of the RNA-binding proteins that form RNPs, TAR DNA-binding protein of 43 kD (TDP43) is of particular interest due to its essential nature and its association with disease. TDP43 plays critical roles in RNA metabolism, many of which require its recruitment to RNP granules such as stress granules, myo-granules, and neuronal transport granules. Moreover, the presence of cytoplasmic TDP43-positive inclusions is a pathological hallmark of several neurodegenerative diseases. Despite the pervasiveness of TDP43 aggregates, TDP43 mutations are exceedingly rare, suggesting that aggregation may be linked to dysregulation of TDP43 function. Oligomerization is a part of normal TDP43 function; thus, it is of interest to understand what triggers the irreversible aggregation that is seen in disease. Herein, we examine TDP43 functions, particularly in RNP granules, and the mechanisms which may explain pathological TDP43 aggregation.
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Affiliation(s)
- Giulia Ada Corbet
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | | | - Roy Parker
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.,Department of Chemistry, Howard Hughes Medical Institute, Chevy Chase, MD, USA
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20
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Mitochondria-Induced Immune Response as a Trigger for Neurodegeneration: A Pathogen from Within. Int J Mol Sci 2021; 22:ijms22168523. [PMID: 34445229 PMCID: PMC8395232 DOI: 10.3390/ijms22168523] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 01/14/2023] Open
Abstract
Symbiosis between the mitochondrion and the ancestor of the eukaryotic cell allowed cellular complexity and supported life. Mitochondria have specialized in many key functions ensuring cell homeostasis and survival. Thus, proper communication between mitochondria and cell nucleus is paramount for cellular health. However, due to their archaebacterial origin, mitochondria possess a high immunogenic potential. Indeed, mitochondria have been identified as an intracellular source of molecules that can elicit cellular responses to pathogens. Compromised mitochondrial integrity leads to release of mitochondrial content into the cytosol, which triggers an unwanted cellular immune response. Mitochondrial nucleic acids (mtDNA and mtRNA) can interact with the same cytoplasmic sensors that are specialized in recognizing genetic material from pathogens. High-energy demanding cells, such as neurons, are highly affected by deficits in mitochondrial function. Notably, mitochondrial dysfunction, neurodegeneration, and chronic inflammation are concurrent events in many severe debilitating disorders. Interestingly in this context of pathology, increasing number of studies have detected immune-activating mtDNA and mtRNA that induce an aberrant production of pro-inflammatory cytokines and interferon effectors. Thus, this review provides new insights on mitochondria-driven inflammation as a potential therapeutic target for neurodegenerative and primary mitochondrial diseases.
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21
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Lehmkuhl EM, Loganathan S, Alsop E, Blythe AD, Kovalik T, Mortimore NP, Barrameda D, Kueth C, Eck RJ, Siddegowda BB, Joardar A, Ball H, Macias ME, Bowser R, Van Keuren-Jensen K, Zarnescu DC. TDP-43 proteinopathy alters the ribosome association of multiple mRNAs including the glypican Dally-like protein (Dlp)/GPC6. Acta Neuropathol Commun 2021; 9:52. [PMID: 33762006 PMCID: PMC7992842 DOI: 10.1186/s40478-021-01148-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 03/06/2021] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a genetically heterogeneous neurodegenerative disease in which 97% of patients exhibit cytoplasmic aggregates containing the RNA binding protein TDP-43. Using tagged ribosome affinity purifications in Drosophila models of TDP-43 proteinopathy, we identified TDP-43 dependent translational alterations in motor neurons impacting the spliceosome, pentose phosphate and oxidative phosphorylation pathways. A subset of the mRNAs with altered ribosome association are also enriched in TDP-43 complexes suggesting that they may be direct targets. Among these, dlp mRNA, which encodes the glypican Dally like protein (Dlp)/GPC6, a wingless (Wg/Wnt) signaling regulator is insolubilized both in flies and patient tissues with TDP-43 pathology. While Dlp/GPC6 forms puncta in the Drosophila neuropil and ALS spinal cords, it is reduced at the neuromuscular synapse in flies suggesting compartment specific effects of TDP-43 proteinopathy. These findings together with genetic interaction data show that Dlp/GPC6 is a novel, physiologically relevant target of TDP-43 proteinopathy.
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Affiliation(s)
- Erik M. Lehmkuhl
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Suvithanandhini Loganathan
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Eric Alsop
- Translational Genomics Research Institute, 445 N 5th St, Phoenix, AZ 85004 USA
| | - Alexander D. Blythe
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Tina Kovalik
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Rd, Phoenix, AZ 85013 USA
| | - Nicholas P. Mortimore
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Dianne Barrameda
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Chuol Kueth
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Randall J. Eck
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Bhavani B. Siddegowda
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Archi Joardar
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Hannah Ball
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Maria E. Macias
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
| | - Robert Bowser
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Rd, Phoenix, AZ 85013 USA
| | | | - Daniela C. Zarnescu
- Department of Cellular and Molecular Biology, University of Arizona, 1007 E. Lowell St, LSS RM 548A, Tucson, AZ 85721 USA
- Department of Neuroscience, University of Arizona, 1040 4th St, Tucson, AZ 85721 USA
- Department of Neurology, University of Arizona, 1501 N Campbell Ave, Tucson, AZ 85724 USA
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22
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Spijkers XM, Pasteuning-Vuhman S, Dorleijn JC, Vulto P, Wevers NR, Pasterkamp RJ. A directional 3D neurite outgrowth model for studying motor axon biology and disease. Sci Rep 2021; 11:2080. [PMID: 33483540 PMCID: PMC7822896 DOI: 10.1038/s41598-021-81335-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 01/04/2021] [Indexed: 01/30/2023] Open
Abstract
We report a method to generate a 3D motor neuron model with segregated and directed axonal outgrowth. iPSC-derived motor neurons are cultured in extracellular matrix gel in a microfluidic platform. Neurons extend their axons into an adjacent layer of gel, whereas dendrites and soma remain predominantly in the somal compartment, as verified by immunofluorescent staining. Axonal outgrowth could be precisely quantified and was shown to respond to the chemotherapeutic drug vincristine in a highly reproducible dose-dependent manner. The model was shown susceptible to excitotoxicity upon exposure with excess glutamate and showed formation of stress granules upon excess glutamate or sodium arsenite exposure, mimicking processes common in motor neuron diseases. Importantly, outgrowing axons could be attracted and repelled through a gradient of axonal guidance cues, such as semaphorins. The platform comprises 40 chips arranged underneath a microtiter plate providing both throughput and compatibility to standard laboratory equipment. The model will thus prove ideal for studying axonal biology and disease, drug discovery and regenerative medicine.
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Affiliation(s)
- Xandor M. Spijkers
- grid.474144.6MIMETAS BV, Organ-On-a-Chip Company, 2333 CH Leiden, The Netherlands ,grid.5477.10000000120346234Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, 3584 CG Utrecht, The Netherlands
| | - Svetlana Pasteuning-Vuhman
- grid.5477.10000000120346234Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, 3584 CG Utrecht, The Netherlands
| | - Jennifa C. Dorleijn
- grid.474144.6MIMETAS BV, Organ-On-a-Chip Company, 2333 CH Leiden, The Netherlands
| | - Paul Vulto
- grid.474144.6MIMETAS BV, Organ-On-a-Chip Company, 2333 CH Leiden, The Netherlands
| | - Nienke R. Wevers
- grid.474144.6MIMETAS BV, Organ-On-a-Chip Company, 2333 CH Leiden, The Netherlands ,grid.10419.3d0000000089452978Department of Cell and Chemical Biology, Leiden University Medical Centre, Einthovenweg 20, 2333 ZC Leiden, The Netherlands
| | - R. Jeroen Pasterkamp
- grid.5477.10000000120346234Department of Translational Neuroscience, University Medical Center Utrecht Brain Center, Utrecht University, 3584 CG Utrecht, The Netherlands
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23
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Smeltzer S, Quadri Z, Miller A, Zamudio F, Hunter J, Stewart NJF, Saji S, Lee DC, Chaput D, Selenica MLB. Hypusination of Eif5a regulates cytoplasmic TDP-43 aggregation and accumulation in a stress-induced cellular model. Biochim Biophys Acta Mol Basis Dis 2021; 1867:165939. [PMID: 32882370 DOI: 10.1016/j.bbadis.2020.165939] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/27/2020] [Accepted: 08/17/2020] [Indexed: 11/23/2022]
Abstract
TAR DNA-binding protein 43 (TDP-43) is a nuclear RNA/DNA binding protein involved in mRNA metabolism. Aberrant mislocalization to the cytoplasm and formation of phosphorylated/aggregated TDP-43 inclusions remains the hallmark pathology in a spectrum of neurodegenerative diseases, including frontotemporal disorders and Alzheimer's disease. Eukaryotic Translation Initiation Factor 5A undergoes a unique post-translation modification of lysine to hypusine (K50), which determines eIF5A binding partners. We used a sodium arsenite-induced cellular stress model to investigate the role of hypusinated eIF5A (eIF5AHypK50) in governing TDP-43 cytoplasmic mislocalization and accumulation in stress granule. Our proteomics and functional data provide evidence that eIF5A interacts with TDP-43 in a hypusine-dependent manner. Additionally, we showed that following stress TDP-43 interactions with eIF5AHypK50 were induced both in the cytoplasm and stress granules. Pharmacological reduction of hypusination or mutations of lysine residues within the hypusine loop decreased phosphorylated and insoluble TDP-43 levels. The proteomic and biochemical analysis also identified nuclear pore complex importins KPNA1/2, KPNB1, and RanGTP as interacting partners of eIF5AHypK50. These findings are the first to provide a novel pathway and potential therapeutic targets that require further investigation in models of TDP-43 proteinopathies.
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Affiliation(s)
- Shayna Smeltzer
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA
| | - Zainuddin Quadri
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA; Sanders-Brown Center on Aging, Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, KY, USA
| | - Abraian Miller
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA
| | - Frank Zamudio
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA
| | - Jordan Hunter
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA
| | - Nicholas J F Stewart
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA
| | - Sheba Saji
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA
| | - Daniel C Lee
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA; Sanders-Brown Center on Aging, Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, KY, USA
| | - Dale Chaput
- Proteomics and Mass Spectrometry Core Facility, Florida Center of Excellence for Drug Discovery and Innovation (CDDI), University of South Florida, 3720 Spectrum Blvd, Suite 303, Tampa, FL 33612, USA
| | - Maj-Linda B Selenica
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, 12901 Bruce B. Downs Blvd, Tampa, FL 33612, USA; Sanders-Brown Center on Aging, Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, KY, USA.
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24
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Dyer MS, Reale LA, Lewis KE, Walker AK, Dickson TC, Woodhouse A, Blizzard CA. Mislocalisation of TDP-43 to the cytoplasm causes cortical hyperexcitability and reduced excitatory neurotransmission in the motor cortex. J Neurochem 2020; 157:1300-1315. [PMID: 33064315 DOI: 10.1111/jnc.15214] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 10/04/2020] [Accepted: 10/06/2020] [Indexed: 12/13/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a chronic neurodegenerative disease pathologically characterised by mislocalisation of the RNA-binding protein TAR-DNA-binding protein 43 (TDP-43) from the nucleus to the cytoplasm. Changes to neuronal excitability and synapse dysfunction in the motor cortex are early pathological changes occurring in people with ALS and mouse models of disease. To investigate the effect of mislocalised TDP-43 on the function of motor cortex neurons we utilised mouse models that express either human wild-type (TDP-43WT ) or nuclear localisation sequence-deficient TDP-43 (TDP-43ΔNLS ) on an inducible promoter that enriches expression to forebrain neurons. Pathophysiology was investigated through immunohistochemistry and whole-cell patch-clamp electrophysiology. Thirty days expression of TDP-43ΔNLS in adult mice did not cause any changes in the number of CTIP2-positive neurons in the motor cortex. However, at this time-point, the expression of TDP-43ΔNLS drives intrinsic hyperexcitability in layer V excitatory neurons of the motor cortex. This hyperexcitability occurs concomitantly with a decrease in excitatory synaptic input to these cells and fluctuations in both directions of ionotropic glutamate receptors. This pathophysiology is not present with TDP-43WT expression, demonstrating that the localisation of TDP-43 to the cytoplasm is crucial for the altered excitability phenotype. This study has important implications for the mechanisms of toxicity of one of the most notorious proteins linked to ALS, TDP-43. We provide the first evidence that TDP-43 mislocalisation causes aberrant synaptic function and a hyperexcitability phenotype in the motor cortex, linking some of the earliest dysfunctions to arise in people with ALS to mislocalisation of TDP-43.
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Affiliation(s)
- Marcus S Dyer
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, Tas, Australia
| | - Laura A Reale
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, Tas, Australia
| | - Katherine E Lewis
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, Tas, Australia
| | - Adam K Walker
- Neurodegeneration Pathobiology Laboratory, Queensland Brain Institute, University of Queensland, Brisbane, Qld, Australia
| | - Tracey C Dickson
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, Tas, Australia
| | - Adele Woodhouse
- Wicking Dementia Research and Education Centre, College of Health and Medicine, University of Tasmania, Hobart, Tas, Australia
| | - Catherine A Blizzard
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, Tas, Australia
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25
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Clark CM, Clark RM, Hoyle JA, Dickson TC. Pathogenic or protective? Neuropeptide Y in amyotrophic lateral sclerosis. J Neurochem 2020; 156:273-289. [PMID: 32654149 DOI: 10.1111/jnc.15125] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/16/2020] [Accepted: 06/24/2020] [Indexed: 12/13/2022]
Abstract
Neuropeptide Y (NPY) is an endogenous peptide of the central and enteric nervous systems which has gained significant interest as a potential neuroprotective agent for treatment of neurodegenerative disease. Amyotrophic lateral sclerosis (ALS) is an aggressive and fatal neurodegenerative disease characterized by motor deficits and motor neuron loss. In ALS, recent evidence from ALS patients and animal models has indicated that NPY may have a role in the disease pathogenesis. Increased NPY levels were found to correlate with disease progression in ALS patients. Similarly, NPY expression is increased in the motor cortex of ALS mice by end stages of the disease. Although the functional consequence of increased NPY levels in ALS is currently unknown, NPY has been shown to exert a diverse range of neuroprotective roles in other neurodegenerative diseases; through modulation of potassium channel activity, increased production of neurotrophins, inhibition of endoplasmic reticulum stress and autophagy, reduction of excitotoxicity, oxidative stress, neuroinflammation and hyperexcitability. Several of these mechanisms and signalling pathways are heavily implicated in the pathogenesis of ALS. Therefore, in this review, we discuss possible effects of NPY and NPY-receptor signalling in the ALS disease context, as determining NPY's contribution to, or impact on, ALS disease mechanisms will be essential for future studies investigating the NPY system as a therapeutic strategy in this devastating disease.
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Affiliation(s)
- Courtney M Clark
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Rosemary M Clark
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Joshua A Hoyle
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Tracey C Dickson
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, TAS, Australia
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26
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Sharkey LM, Sandoval-Pistorius SS, Moore SJ, Gerson JE, Komlo R, Fischer S, Negron-Rios KY, Crowley EV, Padron F, Patel R, Murphy GG, Paulson HL. Modeling UBQLN2-mediated neurodegenerative disease in mice: Shared and divergent properties of wild type and mutant UBQLN2 in phase separation, subcellular localization, altered proteostasis pathways, and selective cytotoxicity. Neurobiol Dis 2020; 143:105016. [PMID: 32653673 DOI: 10.1016/j.nbd.2020.105016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/26/2020] [Accepted: 07/07/2020] [Indexed: 12/12/2022] Open
Abstract
The ubiquitin-binding proteasomal shuttle protein UBQLN2 is implicated in common neurodegenerative disorders due to its accumulation in disease-specific aggregates and, when mutated, directly causes familial frontotemporal dementia/amyotrophic lateral sclerosis (FTD/ALS). Like other proteins linked to FTD/ALS, UBQLN2 undergoes phase separation to form condensates. The relationship of UBQLN2 phase separation and accumulation to neurodegeneration, however, remains uncertain. Employing biochemical, neuropathological and behavioral assays, we studied the impact of overexpressing WT or mutant UBQLN2 in the CNS of transgenic mice. Expression of UBQLN2 harboring a pathogenic mutation (P506T) elicited profound and widespread intraneuronal inclusion formation and aggregation without prominent neurodegenerative or behavioral changes. Both WT and mutant UBQLN2 formed ubiquitin- and P62-positive inclusions in neurons, supporting the view that UBQLN2 is intrinsically prone to phase separate, with the size, shape and frequency of inclusions depending on expression level and the presence or absence of a pathogenic mutation. Overexpression of WT or mutant UBQLN2 resulted in a dose-dependent decrease in levels of a key interacting chaperone, HSP70, as well as dose-dependent profound degeneration of the retina. We conclude that, at least in mice, robust aggregation of a pathogenic form of UBQLN2 is insufficient to cause neuronal loss recapitulating that of human FTD/ALS. Our results nevertheless support the view that altering the normal cellular balance of UBQLN2, whether wild type or mutant protein, has deleterious effects on cells of the CNS and retina that likely reflect perturbations in ubiquitin-dependent protein homeostasis.
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Affiliation(s)
- Lisa M Sharkey
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America.
| | - Stephanie S Sandoval-Pistorius
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, United States of America
| | - Shannon J Moore
- Michigan Neuroscience Institute and Department of Physiology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Julia E Gerson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Robert Komlo
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Svetlana Fischer
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Keyshla Y Negron-Rios
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Emily V Crowley
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Francisco Padron
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Ronak Patel
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Geoffrey G Murphy
- Michigan Neuroscience Institute and Department of Physiology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109-2200, United States of America.
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27
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Weskamp K, Tank EM, Miguez R, McBride JP, Gómez NB, White M, Lin Z, Gonzalez CM, Serio A, Sreedharan J, Barmada SJ. Shortened TDP43 isoforms upregulated by neuronal hyperactivity drive TDP43 pathology in ALS. J Clin Invest 2020; 130:1139-1155. [PMID: 31714900 PMCID: PMC7269575 DOI: 10.1172/jci130988] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 11/06/2019] [Indexed: 12/13/2022] Open
Abstract
Cortical hyperexcitability and mislocalization of the RNA-binding protein TDP43 are highly conserved features in amyotrophic lateral sclerosis (ALS). Nevertheless, the relationship between these phenomena remains poorly defined. Here, we showed that hyperexcitability recapitulates TDP43 pathology by upregulating shortened TDP43 (sTDP43) splice isoforms. These truncated isoforms accumulated in the cytoplasm and formed insoluble inclusions that sequestered full-length TDP43 via preserved N-terminal interactions. Consistent with these findings, sTDP43 overexpression was toxic to mammalian neurons, suggesting neurodegeneration arising from complementary gain- and loss-of-function mechanisms. In humans and mice, sTDP43 transcripts were enriched in vulnerable motor neurons, and we observed a striking accumulation of sTDP43 within neurons and glia of ALS patients. Collectively, these studies uncover a pathogenic role for alternative TDP43 isoforms in ALS, and implicate sTDP43 as a key contributor to the susceptibility of motor neurons in this disorder.
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Affiliation(s)
| | | | | | - Jonathon P. McBride
- Department of Neurology
- Cellular and Molecular Biology Program, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Nicolás B. Gómez
- Department of Neurology
- Cellular and Molecular Biology Program, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Ziqiang Lin
- Department of Basic and Clinical Neuroscience and
| | - Carmen Moreno Gonzalez
- Centre for Craniofacial and Regenerative Biology, King’s College London, London, United Kingdom
| | - Andrea Serio
- Centre for Craniofacial and Regenerative Biology, King’s College London, London, United Kingdom
| | | | - Sami J. Barmada
- Department of Neurology
- Neuroscience Graduate Program, and
- Cellular and Molecular Biology Program, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, USA
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28
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Moore S, Rabichow BE, Sattler R. The Hitchhiker's Guide to Nucleocytoplasmic Trafficking in Neurodegeneration. Neurochem Res 2020; 45:1306-1327. [PMID: 32086712 DOI: 10.1007/s11064-020-02989-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/12/2020] [Accepted: 02/14/2020] [Indexed: 12/12/2022]
Abstract
The widespread nature of nucleocytoplasmic trafficking defects and protein accumulation suggests distinct yet overlapping mechanisms in a variety of neurodegenerative diseases. Detailed understanding of the cellular pathways involved in nucleocytoplasmic transport and its dysregulation are essential for elucidating neurodegenerative pathogenesis and pinpointing potential areas for therapeutic intervention. The transport of cargos from the nucleus to the cytoplasm is generally regulated by the structure and function of the nuclear pore as well as the karyopherin α/β, importin, exportin, and mRNA export mechanisms. The disruption of these crucial transport mechanisms has been extensively described in the context of neurodegenerative diseases. One common theme in neurodegeneration is the cytoplasmic aggregation of proteins, including nuclear RNA binding proteins, repeat expansion associated gene products, and tau. These cytoplasmic aggregations are partly a consequence of failed nucleocytoplasmic transport machinery, but can also further disrupt transport, creating cyclical feed-forward mechanisms that exacerbate neurodegeneration. Here we describe the canonical mechanisms that regulate nucleocytoplasmic trafficking as well as how these mechanisms falter in neurodegenerative diseases.
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Affiliation(s)
- Stephen Moore
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Road, Phoenix, AZ, 85013, USA.,School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Benjamin E Rabichow
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Road, Phoenix, AZ, 85013, USA
| | - Rita Sattler
- Department of Neurobiology, Barrow Neurological Institute, 350 W Thomas Road, Phoenix, AZ, 85013, USA.
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29
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Seranova E, Palhegyi AM, Verma S, Dimova S, Lasry R, Naama M, Sun C, Barrett T, Rosenstock TR, Kumar D, Cohen MA, Buganim Y, Sarkar S. Human Induced Pluripotent Stem Cell Models of Neurodegenerative Disorders for Studying the Biomedical Implications of Autophagy. J Mol Biol 2020; 432:2754-2798. [PMID: 32044344 DOI: 10.1016/j.jmb.2020.01.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/22/2020] [Accepted: 01/23/2020] [Indexed: 12/12/2022]
Abstract
Autophagy is an intracellular degradation process that is essential for cellular survival, tissue homeostasis, and human health. The housekeeping functions of autophagy in mediating the clearance of aggregation-prone proteins and damaged organelles are vital for post-mitotic neurons. Improper functioning of this process contributes to the pathology of myriad human diseases, including neurodegeneration. Impairment in autophagy has been reported in several neurodegenerative diseases where pharmacological induction of autophagy has therapeutic benefits in cellular and transgenic animal models. However, emerging studies suggest that the efficacy of autophagy inducers, as well as the nature of the autophagy defects, may be context-dependent, and therefore, studies in disease-relevant experimental systems may provide more insights for clinical translation to patients. With the advancements in human stem cell technology, it is now possible to establish disease-affected cellular platforms from patients for investigating disease mechanisms and identifying candidate drugs in the appropriate cell types, such as neurons that are otherwise not accessible. Towards this, patient-derived human induced pluripotent stem cells (hiPSCs) have demonstrated considerable promise in constituting a platform for effective disease modeling and drug discovery. Multiple studies have utilized hiPSC models of neurodegenerative diseases to study autophagy and evaluate the therapeutic efficacy of autophagy inducers in neuronal cells. This review provides an overview of the regulation of autophagy, generation of hiPSCs via cellular reprogramming, and neuronal differentiation. It outlines the findings in various neurodegenerative disorders where autophagy has been studied using hiPSC models.
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Affiliation(s)
- Elena Seranova
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Adina Maria Palhegyi
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Surbhi Verma
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom; Cellular Immunology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Simona Dimova
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Rachel Lasry
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Jerusalem, 91120, Israel
| | - Moriyah Naama
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Jerusalem, 91120, Israel
| | - Congxin Sun
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Timothy Barrett
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Tatiana Rosado Rosenstock
- Department of Physiological Science, Santa Casa de São Paulo School of Medical Sciences, São Paulo, SP, 01221-020, Brazil
| | - Dhiraj Kumar
- Cellular Immunology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | - Malkiel A Cohen
- Whitehead Institute for Biomedical Research, Cambridge, MA, 02142, USA
| | - Yosef Buganim
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, The Hebrew University Hadassah Medical School, Jerusalem, 91120, Israel
| | - Sovan Sarkar
- Institute of Cancer and Genomic Sciences, Institute of Biomedical Research, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
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30
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Mejzini R, Flynn LL, Pitout IL, Fletcher S, Wilton SD, Akkari PA. ALS Genetics, Mechanisms, and Therapeutics: Where Are We Now? Front Neurosci 2019; 13:1310. [PMID: 31866818 PMCID: PMC6909825 DOI: 10.3389/fnins.2019.01310] [Citation(s) in RCA: 435] [Impact Index Per Article: 87.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 11/22/2019] [Indexed: 12/11/2022] Open
Abstract
The scientific landscape surrounding amyotrophic lateral sclerosis (ALS) continues to shift as the number of genes associated with the disease risk and pathogenesis, and the cellular processes involved, continues to grow. Despite decades of intense research and over 50 potentially causative or disease-modifying genes identified, etiology remains unexplained and treatment options remain limited for the majority of ALS patients. Various factors have contributed to the slow progress in understanding and developing therapeutics for this disease. Here, we review the genetic basis of ALS, highlighting factors that have contributed to the elusiveness of genetic heritability. The most commonly mutated ALS-linked genes are reviewed with an emphasis on disease-causing mechanisms. The cellular processes involved in ALS pathogenesis are discussed, with evidence implicating their involvement in ALS summarized. Past and present therapeutic strategies and the benefits and limitations of the model systems available to ALS researchers are discussed with future directions for research that may lead to effective treatment strategies outlined.
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Affiliation(s)
- Rita Mejzini
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
| | - Loren L. Flynn
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, Australia
| | - Ianthe L. Pitout
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, Australia
| | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, Australia
| | - Steve D. Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, Australia
| | - P. Anthony Akkari
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA, Australia
- The Perron Institute for Neurological and Translational Science, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, The University of Western Australia, Perth, WA, Australia
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Pobran TD, Forgrave LM, Zheng YZ, Lim JG, Mackenzie IR, DeMarco ML. Detection and characterization of TDP-43 in human cells and tissues by multiple reaction monitoring mass spectrometry. CLINICAL MASS SPECTROMETRY 2019; 14 Pt B:66-73. [DOI: 10.1016/j.clinms.2019.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 07/11/2019] [Accepted: 07/12/2019] [Indexed: 02/07/2023]
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Motor neuron degeneration, severe myopathy and TDP-43 increase in a transgenic pig model of SOD1-linked familiar ALS. Neurobiol Dis 2018; 124:263-275. [PMID: 30471417 DOI: 10.1016/j.nbd.2018.11.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 10/26/2018] [Accepted: 11/19/2018] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a neural disorder gradually leading to paralysis of the whole body. Alterations in superoxide dismutase SOD1 gene have been linked with several variants of familial ALS. Here, we investigated a transgenic (Tg) cloned swine model expressing the human pathological hSOD1G93A allele. As in patients, these Tg pigs transmitted the disease to the progeny with an autosomal dominant trait and showed ALS onset from about 27 months of age. Post mortem analysis revealed motor neuron (MN) degeneration, gliosis and hSOD1 protein aggregates in brainstem and spinal cord. Severe skeletal muscle pathology including necrosis and inflammation was observed at the end stage, as well. Remarkably, as in human patients, these Tg pigs showed a quite long presymptomatic phase in which gradually increasing amounts of TDP-43 were detected in peripheral blood mononuclear cells. Thus, this transgenic swine model opens the unique opportunity to investigate ALS biomarkers even before disease onset other than testing novel drugs and possible medical devices.
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Chung CG, Lee H, Lee SB. Mechanisms of protein toxicity in neurodegenerative diseases. Cell Mol Life Sci 2018; 75:3159-3180. [PMID: 29947927 PMCID: PMC6063327 DOI: 10.1007/s00018-018-2854-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 06/06/2018] [Accepted: 06/07/2018] [Indexed: 12/12/2022]
Abstract
Protein toxicity can be defined as all the pathological changes that ensue from accumulation, mis-localization, and/or multimerization of disease-specific proteins. Most neurodegenerative diseases manifest protein toxicity as one of their key pathogenic mechanisms, the details of which remain unclear. By systematically deconstructing the nature of toxic proteins, we aim to elucidate and illuminate some of the key mechanisms of protein toxicity from which therapeutic insights may be drawn. In this review, we focus specifically on protein toxicity from the point of view of various cellular compartments such as the nucleus and the mitochondria. We also discuss the cell-to-cell propagation of toxic disease proteins that complicates the mechanistic understanding of the disease progression as well as the spatiotemporal point at which to therapeutically intervene. Finally, we discuss selective neuronal vulnerability, which still remains largely enigmatic.
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Affiliation(s)
- Chang Geon Chung
- Department of Brain and Cognitive Sciences, DGIST, Daegu, 42988, Republic of Korea
| | - Hyosang Lee
- Department of Brain and Cognitive Sciences, DGIST, Daegu, 42988, Republic of Korea.
| | - Sung Bae Lee
- Department of Brain and Cognitive Sciences, DGIST, Daegu, 42988, Republic of Korea.
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34
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Posa D, Martínez-González L, Bartolomé F, Nagaraj S, Porras G, Martínez A, Martín-Requero Á. Recapitulation of Pathological TDP-43 Features in Immortalized Lymphocytes from Sporadic ALS Patients. Mol Neurobiol 2018; 56:2424-2432. [PMID: 30030753 DOI: 10.1007/s12035-018-1249-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/15/2018] [Indexed: 11/24/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal progressive neurodegenerative disorder of still unknown etiology that results in loss of motoneurons, paralysis, and death, usually between 2 and 4 years from onset. There are no currently available ALS biomarkers to support early diagnosis and to facilitate the assessment of the efficacy of new treatments. Since ALS is considered a multisystemic disease, here we have investigated the usefulness of immortalized lymphocytes from sporadic ALS patients to study TDP-43 homeostasis as well as to provide a convenient platform to evaluate TDP-43 phosphorylation as a novel therapeutic approach for ALS. We report here that lymphoblasts from ALS patients recapitulate the hallmarks of TDP-43 processing in affected motoneurons, such as increased phosphorylation, truncation, and mislocalization of TDP-43. Moreover, modulation of TDP-43 by an in-house designed protein casein kinase-1δ (CK-1δ) inhibitor, IGS3.27, reduced phosphorylation of TDP-43, and normalized the nucleo-cytosol translocation of TDP-43 in ALS lymphoblasts. Therefore, we conclude that lymphoblasts, easily accessible cells, from ALS patients could be a useful model to study pathological features of ALS disease and a suitable platform to test the effects of potential disease-modifying drugs even in a personalized manner.
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Affiliation(s)
- Diana Posa
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Loreto Martínez-González
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Fernando Bartolomé
- Neurodegenerative Disorders Group, Instituto de Investigacion Hospital 12 de Octubre, Madrid, Spain.,CIBER de Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Siranjeevi Nagaraj
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain.,Laboratory of Preclinical Testing of Higher Standard, Nencki Institute of Experimental Biology, Polish Academy of Science, Pasteur 3 St, 02-093, Warsaw, Poland
| | - Gracia Porras
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - Ana Martínez
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain.
| | - Ángeles Martín-Requero
- Department of Molecular Biomedicine, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain.
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35
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Jeon GS, Shim YM, Lee DY, Kim JS, Kang M, Ahn SH, Shin JY, Geum D, Hong YH, Sung JJ. Pathological Modification of TDP-43 in Amyotrophic Lateral Sclerosis with SOD1 Mutations. Mol Neurobiol 2018; 56:2007-2021. [PMID: 29982983 PMCID: PMC6394608 DOI: 10.1007/s12035-018-1218-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 06/29/2018] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal, adult-onset, progressive neurodegenerative disorder with no known cure. Cu/Zn-superoxide dismutase (SOD1) was the first identified protein associated with familial ALS (fALS). Recently, TAR DNA-binding protein 43 (TDP-43) has been found to be a principal component of ubiquitinated cytoplasmic inclusions in neurons and glia in ALS. However, it remains unclear whether these ALS-linked proteins partly have a shared pathogenesis. Here, we determine the association between mutant SOD1 and the modification of TDP-43 and the relationship of pathologic TDP-43 to neuronal cytotoxicity in SOD1 ALS. In this work, using animal model, human tissue, and cell models, we provide the evidence that the association between the TDP-43 modification and the pathogenesis of SOD1 fALS. We demonstrated an age-dependent increase in TDP-43 C-terminal fragments and phosphorylation in motor neurons and glia of SOD1 mice and SOD1G85S ALS patient. Cytoplasmic TDP-43 was also observed in iPSC-derived motor neurons from SOD1G17S ALS patient. Moreover, we observed that mutant SOD1 interacts with TDP-43 in co-immunoprecipitation assays with G93A hSOD1-transfected cell lines. Mutant SOD1 overexpression led to an increase in TDP-43 modification in the detergent-insoluble fraction in the spinal cord of SOD1 mice and fALS patient. Additionally, we showed cellular apoptosis in response to the interaction of mutant SOD1 and fragment forms of TDP-43. These findings suggest that mutant SOD1 could affect the solubility/insolubility of TDP-43 through physical interactions and the resulting pathological modifications of TDP-43 may be involved in motor neuron death in SOD1 fALS.
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Affiliation(s)
- Gye Sun Jeon
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, South Korea
| | - Yu-Mi Shim
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea
| | - Do-Yeon Lee
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea
| | - Jun-Soon Kim
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea
| | - MinJin Kang
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, South Korea
| | - So Hyun Ahn
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea
| | - Je-Young Shin
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea
| | - Dongho Geum
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, South Korea
| | - Yoon Ho Hong
- Department of Neurology, Seoul National University Seoul Metropolitan Government Boramae Medical Center, Seoul, South Korea
| | - Jung-Joon Sung
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea. .,Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, South Korea.
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36
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Coyne AN, Lorenzini I, Chou CC, Torvund M, Rogers RS, Starr A, Zaepfel BL, Levy J, Johannesmeyer J, Schwartz JC, Nishimune H, Zinsmaier K, Rossoll W, Sattler R, Zarnescu DC. Post-transcriptional Inhibition of Hsc70-4/HSPA8 Expression Leads to Synaptic Vesicle Cycling Defects in Multiple Models of ALS. Cell Rep 2018; 21:110-125. [PMID: 28978466 DOI: 10.1016/j.celrep.2017.09.028] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 05/09/2017] [Accepted: 09/07/2017] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a synaptopathy accompanied by the presence of cytoplasmic aggregates containing TDP-43, an RNA-binding protein linked to ∼97% of ALS cases. Using a Drosophila model of ALS, we show that TDP-43 overexpression (OE) in motor neurons results in decreased expression of the Hsc70-4 chaperone at the neuromuscular junction (NMJ). Mechanistically, mutant TDP-43 sequesters hsc70-4 mRNA and impairs its translation. Expression of the Hsc70-4 ortholog, HSPA8, is also reduced in primary motor neurons and NMJs of mice expressing mutant TDP-43. Electrophysiology, imaging, and genetic interaction experiments reveal TDP-43-dependent defects in synaptic vesicle endocytosis. These deficits can be partially restored by OE of Hsc70-4, cysteine-string protein (Csp), or dynamin. This suggests that TDP-43 toxicity results in part from impaired activity of the synaptic CSP/Hsc70 chaperone complex impacting dynamin function. Finally, Hsc70-4/HSPA8 expression is also post-transcriptionally reduced in fly and human induced pluripotent stem cell (iPSC) C9orf72 models, suggesting a common disease pathomechanism.
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Affiliation(s)
- Alyssa N Coyne
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA; Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA
| | - Ileana Lorenzini
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
| | - Ching-Chieh Chou
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Meaghan Torvund
- Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA
| | - Robert S Rogers
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS 66160, USA
| | - Alexander Starr
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
| | - Benjamin L Zaepfel
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Jennifer Levy
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
| | - Jeffrey Johannesmeyer
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Jacob C Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Hiroshi Nishimune
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS 66160, USA
| | - Konrad Zinsmaier
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA; Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA
| | - Wilfried Rossoll
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Rita Sattler
- Department of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
| | - Daniela C Zarnescu
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA; Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA; Department of Neurology, University of Arizona, Tucson, AZ 85721, USA.
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37
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Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating, uniformly lethal degenerative disorder of motor neurons that overlaps clinically with frontotemporal dementia (FTD). Investigations of the 10% of ALS cases that are transmitted as dominant traits have revealed numerous gene mutations and variants that either cause these disorders or influence their clinical phenotype. The evolving understanding of the genetic architecture of ALS has illuminated broad themes in the molecular pathophysiology of both familial and sporadic ALS and FTD. These central themes encompass disturbances of protein homeostasis, alterations in the biology of RNA binding proteins, and defects in cytoskeletal dynamics, as well as numerous downstream pathophysiological events. Together, these findings from ALS genetics provide new insight into therapies that target genetically distinct subsets of ALS and FTD.
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Affiliation(s)
- Mehdi Ghasemi
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
| | - Robert H Brown
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
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38
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TDP43 nuclear export and neurodegeneration in models of amyotrophic lateral sclerosis and frontotemporal dementia. Sci Rep 2018; 8:4606. [PMID: 29545601 PMCID: PMC5854632 DOI: 10.1038/s41598-018-22858-w] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 03/02/2018] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are progressive neurodegenerative disorders marked in most cases by the nuclear exclusion and cytoplasmic deposition of the RNA binding protein TDP43. We previously demonstrated that ALS-associated mutant TDP43 accumulates within the cytoplasm, and that TDP43 mislocalization predicts neurodegeneration. Here, we sought to prevent neurodegeneration in ALS/FTD models using selective inhibitor of nuclear export (SINE) compounds that target exportin-1 (XPO1). SINE compounds modestly extend cellular survival in neuronal ALS/FTD models and mitigate motor symptoms in an in vivo rat ALS model. At high doses, SINE compounds block nuclear egress of an XPO1 cargo reporter, but not at lower concentrations that were associated with neuroprotection. Neither SINE compounds nor leptomycin B, a separate XPO1 inhibitor, enhanced nuclear TDP43 levels, while depletion of XPO1 or other exportins had little effect on TDP43 localization, suggesting that no single exporter is necessary for TDP43 export. Supporting this hypothesis, we find overexpression of XPO1, XPO7 and NXF1 are each sufficient to promote nuclear TDP43 egress. Taken together, our results indicate that redundant pathways regulate TDP43 nuclear export, and that therapeutic prevention of cytoplasmic TDP43 accumulation in ALS/FTD may be enhanced by targeting several overlapping mechanisms.
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39
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Weskamp K, Barmada SJ. TDP43 and RNA instability in amyotrophic lateral sclerosis. Brain Res 2018; 1693:67-74. [PMID: 29395044 DOI: 10.1016/j.brainres.2018.01.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 01/09/2018] [Accepted: 01/12/2018] [Indexed: 12/13/2022]
Abstract
The nuclear RNA-binding protein TDP43 is integrally involved in RNA processing. In accord with this central function, TDP43 levels are tightly regulated through a negative feedback loop, in which TDP43 recognizes its own RNA transcript, destabilizes it, and reduces new TDP43 protein production. In the neurodegenerative disorder amyotrophic lateral sclerosis (ALS), cytoplasmic mislocalization and accumulation of TDP43 disrupt autoregulation; conversely, inefficient TDP43 autoregulation can lead to cytoplasmic TDP43 deposition and subsequent neurodegeneration. Because TDP43 plays a multifaceted role in maintaining RNA metabolism, its mislocalization and accumulation interrupt several RNA processing pathways that in turn affect RNA stability and gene expression. TDP43-mediated disruption of these pathways-including alternative mRNA splicing, non-coding RNA processing, and RNA granule dynamics-may directly or indirectly contribute to ALS pathogenesis. Therefore, strategies that restore effective TDP43 autoregulation may ultimately prevent neurodegeneration in ALS and related disorders.
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Affiliation(s)
- Kaitlin Weskamp
- Neuroscience Graduate Program and Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI, United States
| | - Sami J Barmada
- Neuroscience Graduate Program and Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI, United States.
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40
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Ayyadevara S, Balasubramaniam M, Kakraba S, Alla R, Mehta JL, Shmookler Reis RJ. Aspirin-Mediated Acetylation Protects Against Multiple Neurodegenerative Pathologies by Impeding Protein Aggregation. Antioxid Redox Signal 2017; 27:1383-1396. [PMID: 28537433 PMCID: PMC5661865 DOI: 10.1089/ars.2016.6978] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
AIMS Many progressive neurological disorders, including Alzheimer's disease (AD), Huntington's disease, and Parkinson's disease (PD), are characterized by accumulation of insoluble protein aggregates. In prospective trials, the cyclooxygenase inhibitor aspirin (acetylsalicylic acid) reduced the risk of AD and PD, as well as cardiovascular events and many late-onset cancers. Considering the role played by protein hyperphosphorylation in aggregation and neurodegenerative diseases, and aspirin's known ability to donate acetyl groups, we asked whether aspirin might reduce both phosphorylation and aggregation by acetylating protein targets. RESULTS Aspirin was substantially more effective than salicylate in reducing or delaying aggregation in human neuroblastoma cells grown in vitro, and in Caenorhabditis elegans models of human neurodegenerative diseases in vivo. Aspirin acetylates many proteins, while reducing phosphorylation, suggesting that acetylation may oppose phosphorylation. Surprisingly, acetylated proteins were largely excluded from compact aggregates. Molecular-dynamic simulations indicate that acetylation of amyloid peptide energetically disfavors its association into dimers and octamers, and oligomers that do form are less compact and stable than those comprising unacetylated peptides. INNOVATION Hyperphosphorylation predisposes certain proteins to aggregate (e.g., tau, α-synuclein, and transactive response DNA-binding protein 43 [TDP-43]), and it is a critical pathogenic marker in both cardiovascular and neurodegenerative diseases. We present novel evidence that acetylated proteins are underrepresented in protein aggregates, and that aggregation varies inversely with acetylation propensity after diverse genetic and pharmacologic interventions. CONCLUSIONS These results are consistent with the hypothesis that aspirin inhibits protein aggregation and the ensuing toxicity of aggregates through its acetyl-donating activity. This mechanism may contribute to the neuro-protective, cardio-protective, and life-prolonging effects of aspirin. Antioxid. Redox Signal. 27, 1383-1396.
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Affiliation(s)
- Srinivas Ayyadevara
- 1 Central Arkansas Veterans Healthcare System, Research & Development Service , Little Rock, Arkansas.,2 Department of Geriatrics, Reynolds Institute on Aging, University of Arkansas for Medical Sciences , Little Rock, Arkansas
| | - Meenakshisundaram Balasubramaniam
- 1 Central Arkansas Veterans Healthcare System, Research & Development Service , Little Rock, Arkansas.,2 Department of Geriatrics, Reynolds Institute on Aging, University of Arkansas for Medical Sciences , Little Rock, Arkansas
| | - Samuel Kakraba
- 3 Bioinformatics Program, University of Arkansas for Medical Sciences, and University of Arkansas at Little Rock , Little Rock, Arkansas
| | - Ramani Alla
- 1 Central Arkansas Veterans Healthcare System, Research & Development Service , Little Rock, Arkansas.,2 Department of Geriatrics, Reynolds Institute on Aging, University of Arkansas for Medical Sciences , Little Rock, Arkansas
| | - Jawahar L Mehta
- 1 Central Arkansas Veterans Healthcare System, Research & Development Service , Little Rock, Arkansas.,4 Divison of Cardiology, Department of Medicine, University of Arkansas for Medical Sciences , Little Rock, Arkansas
| | - Robert J Shmookler Reis
- 1 Central Arkansas Veterans Healthcare System, Research & Development Service , Little Rock, Arkansas.,2 Department of Geriatrics, Reynolds Institute on Aging, University of Arkansas for Medical Sciences , Little Rock, Arkansas.,3 Bioinformatics Program, University of Arkansas for Medical Sciences, and University of Arkansas at Little Rock , Little Rock, Arkansas
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41
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Polymenidou M, Cleveland DW. Biological Spectrum of Amyotrophic Lateral Sclerosis Prions. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a024133. [PMID: 28062558 DOI: 10.1101/cshperspect.a024133] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia (FTLD) are two neurodegenerative diseases with distinct clinical features but common genetic causes and neuropathological signatures. Ten years after the RNA-binding protein TDP-43 was discovered as the main protein in the cytoplasmic inclusions that characterize ALS and FTLD, their pathogenic mechanisms have never seemed more complex. Indeed, discoveries of the past decade have revolutionized our understanding of these diseases, highlighting their genetic heterogeneity and the involvement of protein-RNA assemblies in their pathogenesis. Importantly, these assemblies serve as the foci of protein misfolding and mature into insoluble structures, which further recruit native proteins, turning them into misfolded forms. This self-perpetuating mechanism is a twisted version of classical prion replication that leads to amplification of pathological protein complexes that spread throughout the neuraxis, offering a pathogenic principle that underlies the rapid disease progression that characterizes ALS and FTLD.
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Affiliation(s)
- Magdalini Polymenidou
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Don W Cleveland
- Ludwig Institute for Cancer Research and Department of Cellular and Molecular Medicine, University of California, 9500 Gilman Drive, San Diego, La Jolla, California 92093-0670
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42
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Byrne DJ, Harmon MJ, Simpson JC, Blackstone C, O'Sullivan NC. Roles for the VCP co-factors Npl4 and Ufd1 in neuronal function in Drosophila melanogaster. J Genet Genomics 2017; 44:493-501. [PMID: 29037990 PMCID: PMC5666124 DOI: 10.1016/j.jgg.2017.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/02/2017] [Accepted: 06/19/2017] [Indexed: 12/18/2022]
Abstract
The VCP-Ufd1-Npl4 complex regulates proteasomal processing within cells by delivering ubiquitinated proteins to the proteasome for degradation. Mutations in VCP are associated with two neurodegenerative diseases, amyotrophic lateral sclerosis (ALS) and inclusion body myopathy with Paget's disease of the bone and frontotemporal dementia (IBMPFD), and extensive study has revealed crucial functions of VCP within neurons. By contrast, little is known about the functions of Npl4 or Ufd1 in vivo. Using neuronal-specific knockdown of Npl4 or Ufd1 in Drosophila melanogaster, we infer that Npl4 contributes to microtubule organization within developing motor neurons. Moreover, Npl4 RNAi flies present with neurodegenerative phenotypes including progressive locomotor deficits, reduced lifespan and increased accumulation of TAR DNA-binding protein-43 homolog (TBPH). Knockdown, but not overexpression, of TBPH also exacerbates Npl4 RNAi-associated adult-onset neurodegenerative phenotypes. In contrast, we find that neuronal knockdown of Ufd1 has little effect on neuromuscular junction (NMJ) organization, TBPH accumulation or adult behaviour. These findings suggest the differing neuronal functions of Npl4 and Ufd1 in vivo.
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Affiliation(s)
- Dwayne J Byrne
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Mark J Harmon
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Jeremy C Simpson
- UCD School of Biology and Environmental Science, UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland
| | - Craig Blackstone
- Cell Biology Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Niamh C O'Sullivan
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland.
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43
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Restoration of Motor Defects Caused by Loss of Drosophila TDP-43 by Expression of the Voltage-Gated Calcium Channel, Cacophony, in Central Neurons. J Neurosci 2017; 37:9486-9497. [PMID: 28847811 DOI: 10.1523/jneurosci.0554-17.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 08/17/2017] [Accepted: 08/19/2017] [Indexed: 01/08/2023] Open
Abstract
Defects in the RNA-binding protein, TDP-43, are known to cause a variety of neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal lobar dementia. A variety of experimental systems have shown that neurons are sensitive to TDP-43 expression levels, yet the specific functional defects resulting from TDP-43 dysregulation have not been well described. Using the Drosophila TDP-43 ortholog TBPH, we previously showed that TBPH-null animals display locomotion defects as third instar larvae. Furthermore, loss of TBPH caused a reduction in cacophony, a Type II voltage-gated calcium channel, expression and that genetically restoring cacophony in motor neurons in TBPH mutant animals was sufficient to rescue the locomotion defects. In the present study, we examined the relative contributions of neuromuscular junction physiology and the motor program to the locomotion defects and identified subsets of neurons that require cacophony expression to rescue the defects. At the neuromuscular junction, we showed mEPP amplitudes and frequency require TBPH. Cacophony expression in motor neurons rescued mEPP frequency but not mEPP amplitude. We also showed that TBPH mutants displayed reduced motor neuron bursting and coordination during crawling and restoring cacophony selectively in two pairs of cells located in the brain, the AVM001b/2b neurons, also rescued the locomotion and motor defects, but not the defects in neuromuscular junction physiology. These results suggest that the behavioral defects associated with loss of TBPH throughout the nervous system can be associated with defects in a small number of genes in a limited number of central neurons, rather than peripheral defects.SIGNIFICANCE STATEMENT TDP-43 dysfunction is a common feature in neurodegenerative diseases, including amyotrophic lateral sclerosis, frontotemporal lobar dementia, and Alzheimer's disease. Loss- and gain-of-function models have shown that neurons are sensitive to TDP-43 expression levels, but the specific defects caused by TDP-43 loss of function have not been described in detail. A Drosophila loss-of-function model displays pronounced locomotion defects that can be reversed by restoring the expression levels of a voltage-gated calcium channel, cacophony. We show these defects can be rescued by expression of cacophony in motor neurons and by expression in two pairs of neurons in the brain. These data suggest that loss of TDP-43 can disrupt the central circuitry of the CNS, opening up identification of alternative therapeutic targets for TDP-43 proteinopathies.
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Osuru HP, Pramoonjago P, Abhyankar MM, Swanson E, Roker LA, Cathro H, Reddi PP. Immunolocalization of TAR DNA-binding protein of 43 kDa (TDP-43) in mouse seminiferous epithelium. Mol Reprod Dev 2017; 84:675-685. [PMID: 28600885 DOI: 10.1002/mrd.22851] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/19/2017] [Accepted: 05/25/2017] [Indexed: 12/13/2022]
Abstract
TAR DNA-binding protein of 43 kDa (TDP-43) is an evolutionarily conserved, ubiquitously expressed, multi-functional DNA/RNA-binding protein with roles in gene transcription, mRNA splicing, stability, transport, micro RNA biogenesis, and suppression of transposons. Aberrant expression of TDP-43 in testis and sperm was recently shown to be associated with male infertility, which highlights the need to understand better the expression of TDP-43 in the testis. We previously cloned TDP-43 from a mouse testis cDNA library, and showed that it functions as a transcriptional repressor and regulates the precise spatiotemporal expression of the Acrv1 gene, which encodes the acrosomal protein SP-10, during spermatogenesis. Here, we performed immunoblotting and immunohistochemistry of the mouse testis using four separate antibodies recognizing the amino and carboxyl termini of TDP-43. TDP-43 is present in the nuclei of germ cells as well as Sertoli cells. TDP-43 expression begins in type B/intermediate spermatogonia, peaks in preleptotene spermatocytes, and becomes undetectable in leptotene and zygotene spermatocytes. Pachytene spermatocytes and early round spermatids again express TDP-43, but its abundance diminishes later in spermatids (at steps 5-8). Interestingly, two of the four antibodies showed TDP-43 expression in spermatids at steps 9-10, which coincides with the initial phase of the histone-to-protamine transition. Immunoreactivity patterns observed in the study suggest that TDP-43 assumes different conformational states at different stages of spermatogenesis. TDP-43 pathology has been extensively studied in the context of neurodegenerative diseases; its role in spermatogenesis warrants further detailed investigation of the involvement of TDP-43 in male infertility.
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Affiliation(s)
- Hari Prasad Osuru
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Patcharin Pramoonjago
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Mayuresh M Abhyankar
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Eric Swanson
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia
| | - LaToya Ann Roker
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Helen Cathro
- Department of Pathology, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Prabhakara P Reddi
- Department of Comparative Biosciences, University of Illinois at Urbana Champaign, Urbana, Illinois
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45
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Shahheydari H, Ragagnin A, Walker AK, Toth RP, Vidal M, Jagaraj CJ, Perri ER, Konopka A, Sultana JM, Atkin JD. Protein Quality Control and the Amyotrophic Lateral Sclerosis/Frontotemporal Dementia Continuum. Front Mol Neurosci 2017; 10:119. [PMID: 28539871 PMCID: PMC5423993 DOI: 10.3389/fnmol.2017.00119] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/10/2017] [Indexed: 12/11/2022] Open
Abstract
Protein homeostasis, or proteostasis, has an important regulatory role in cellular function. Protein quality control mechanisms, including protein folding and protein degradation processes, have a crucial function in post-mitotic neurons. Cellular protein quality control relies on multiple strategies, including molecular chaperones, autophagy, the ubiquitin proteasome system, endoplasmic reticulum (ER)-associated degradation (ERAD) and the formation of stress granules (SGs), to regulate proteostasis. Neurodegenerative diseases are characterized by the presence of misfolded protein aggregates, implying that protein quality control mechanisms are dysfunctional in these conditions. Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases that are now recognized to overlap clinically and pathologically, forming a continuous disease spectrum. In this review article, we detail the evidence for dysregulation of protein quality control mechanisms across the whole ALS-FTD continuum, by discussing the major proteins implicated in ALS and/or FTD. We also discuss possible ways in which protein quality mechanisms could be targeted therapeutically in these disorders and highlight promising protein quality control-based therapeutics for clinical trials.
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Affiliation(s)
- Hamideh Shahheydari
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Audrey Ragagnin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Adam K Walker
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Reka P Toth
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Marta Vidal
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Cyril J Jagaraj
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Emma R Perri
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Anna Konopka
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Jessica M Sultana
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia
| | - Julie D Atkin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie UniversitySydney, NSW, Australia.,Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe UniversityMelbourne, VIC, Australia
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46
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Moujalled D, Grubman A, Acevedo K, Yang S, Ke YD, Moujalled DM, Duncan C, Caragounis A, Perera ND, Turner BJ, Prudencio M, Petrucelli L, Blair I, Ittner LM, Crouch PJ, Liddell JR, White AR. TDP-43 mutations causing amyotrophic lateral sclerosis are associated with altered expression of RNA-binding protein hnRNP K and affect the Nrf2 antioxidant pathway. Hum Mol Genet 2017; 26:1732-1746. [PMID: 28334913 DOI: 10.1093/hmg/ddx093] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/07/2017] [Indexed: 12/12/2022] Open
Abstract
TAR DNA binding protein 43 (TDP-43) is a major disease-associated protein involved in the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U). Our previous studies found a direct association between TDP-43 and heterogeneous nuclear ribonucleoprotein K (hnRNP K). In this study, utilizing ALS patient fibroblasts harboring a TDP-43M337V mutation and NSC-34 motor neuronal cell line expressing TDP-43Q331K mutation, we show that hnRNP K expression is impaired in urea soluble extracts from mutant TDP-43 cell models. This was confirmed in vivo using TDP-43Q331K and inducible TDP-43A315T murine ALS models. We further investigated the potential pathological effects of mutant TDP-43-mediated changes to hnRNP K metabolism by RNA binding immunoprecipitation analysis. hnRNP K protein was bound to antioxidant NFE2L2 transcripts encoding Nrf2 antioxidant transcription factor, with greater enrichment in TDP-43M337V patient fibroblasts compared to healthy controls. Subsequent gene expression profiling revealed an increase in downstream antioxidant transcript expression of Nrf2 signaling in the spinal cord of TDP-43Q331K mice compared to control counterparts, yet the corresponding protein expression was not up-regulated in transgenic mice. Despite the elevated expression of antioxidant transcripts, we observed impaired levels of glutathione (downstream Nrf2 antioxidant) in TDP-43M337V patient fibroblasts and astrocyte cultures from TDP-43Q331K mice, indicative of elevated oxidative stress and failure of some upregulated antioxidant genes to be translated into protein. Our findings indicate that further exploration of the interplay between hnRNP K (or other hnRNPs) and Nrf2-mediated antioxidant signaling is warranted and may be an important driver for motor neuron degeneration in ALS.
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Affiliation(s)
- Diane Moujalled
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia
| | - Alexandra Grubman
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia
| | - Karla Acevedo
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia
| | - Shu Yang
- The Australian School of Advanced Medicine, Macquarie University, NSW 2109, Australia
| | - Yazi D Ke
- Dementia Research Unit, Department of Anatomy, Faculty of Medicine, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia
| | - Donia M Moujalled
- Australian Centre for Blood Diseases (ACBD), The Alfred Centre, Victoria 3004, Australia
| | - Clare Duncan
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria 3010, Australia
| | | | - Nirma D Perera
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria 3010, Australia
| | - Bradley J Turner
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria 3010, Australia
| | | | | | - Ian Blair
- The Australian School of Advanced Medicine, Macquarie University, NSW 2109, Australia
| | - Lars M Ittner
- Dementia Research Unit, Department of Anatomy, Faculty of Medicine, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia
| | - Peter J Crouch
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria 3010, Australia
| | - Jeffrey R Liddell
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia
| | - Anthony R White
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria 3010, Australia
- Berghofer Medical Research Institute, Herston, Queensland 4006, Australia
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Bhandare VV, Ramaswamy A. The proteinopathy of D169G and K263E mutants at the RNA Recognition Motif (RRM) domain of tar DNA-binding protein (tdp43) causing neurological disorders: A computational study. J Biomol Struct Dyn 2017; 36:1075-1093. [DOI: 10.1080/07391102.2017.1310670] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
| | - Amutha Ramaswamy
- Centre for Bioinformatics, Pondicherry University, Pondicherry 605014, India
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48
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Krug L, Chatterjee N, Borges-Monroy R, Hearn S, Liao WW, Morrill K, Prazak L, Rozhkov N, Theodorou D, Hammell M, Dubnau J. Retrotransposon activation contributes to neurodegeneration in a Drosophila TDP-43 model of ALS. PLoS Genet 2017; 13:e1006635. [PMID: 28301478 PMCID: PMC5354250 DOI: 10.1371/journal.pgen.1006635] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 02/14/2017] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are two incurable neurodegenerative disorders that exist on a symptomological spectrum and share both genetic underpinnings and pathophysiological hallmarks. Functional abnormality of TAR DNA-binding protein 43 (TDP-43), an aggregation-prone RNA and DNA binding protein, is observed in the vast majority of both familial and sporadic ALS cases and in ~40% of FTLD cases, but the cascade of events leading to cell death are not understood. We have expressed human TDP-43 (hTDP-43) in Drosophila neurons and glia, a model that recapitulates many of the characteristics of TDP-43-linked human disease including protein aggregation pathology, locomotor impairment, and premature death. We report that such expression of hTDP-43 impairs small interfering RNA (siRNA) silencing, which is the major post-transcriptional mechanism of retrotransposable element (RTE) control in somatic tissue. This is accompanied by de-repression of a panel of both LINE and LTR families of RTEs, with somewhat different elements being active in response to hTDP-43 expression in glia versus neurons. hTDP-43 expression in glia causes an early and severe loss of control of a specific RTE, the endogenous retrovirus (ERV) gypsy. We demonstrate that gypsy causes the degenerative phenotypes in these flies because we are able to rescue the toxicity of glial hTDP-43 either by genetically blocking expression of this RTE or by pharmacologically inhibiting RTE reverse transcriptase activity. Moreover, we provide evidence that activation of DNA damage-mediated programmed cell death underlies both neuronal and glial hTDP-43 toxicity, consistent with RTE-mediated effects in both cell types. Our findings suggest a novel mechanism in which RTE activity contributes to neurodegeneration in TDP-43-mediated diseases such as ALS and FTLD.
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Affiliation(s)
- Lisa Krug
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Nabanita Chatterjee
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | | | - Stephen Hearn
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Wen-Wei Liao
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Kathleen Morrill
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Lisa Prazak
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
- Department of Biology, Farmingdale State College, Farmingdale, NY United States of America
| | - Nikolay Rozhkov
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Delphine Theodorou
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Molly Hammell
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Josh Dubnau
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
- Department of Anesthesiology, Stony Brook School of Medicine, Stony Brook, New York, United States of America
- Department of Neurobiology and Behavior, Stony Brook School of Medicine, Stony Brook, New York, United States of America
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Altered Intracellular Milieu of ADAR2-Deficient Motor Neurons in Amyotrophic Lateral Sclerosis. Genes (Basel) 2017; 8:genes8020060. [PMID: 28208729 PMCID: PMC5333049 DOI: 10.3390/genes8020060] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/25/2017] [Accepted: 01/26/2017] [Indexed: 12/12/2022] Open
Abstract
Transactive response DNA-binding protein (TDP-43) pathology, and failure of A-to-I conversion (RNA editing) at the glutamine/arginine (Q/R) site of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor subunit GluA2, are etiology-linked molecular abnormalities that concomitantly occur in the motor neurons of most patients with amyotrophic lateral sclerosis (ALS). Adenosine deaminase acting on RNA 2 (ADAR2) specifically catalyzes GluA2 Q/R site-RNA editing. Furthermore, conditional ADAR2 knockout mice (AR2) exhibit a progressive ALS phenotype with TDP-43 pathology in the motor neurons, which is the most reliable pathological marker of ALS. Therefore, the evidence indicates that ADAR2 downregulation is a causative factor in ALS, and AR2 mice exhibit causative molecular changes that occur in ALS. We discuss the contributors to ADAR2 downregulation and TDP-43 pathology in AR2 mouse motor neurons. We describe mechanisms of exaggerated Ca2+ influx amelioration via AMPA receptors, which is neuroprotective in ADAR2-deficient motor neurons with normalization of TDP-43 pathology in AR2 mice. Development of drugs to treat diseases requires appropriate animal models and a sensitive method of evaluating efficacy. Therefore, normalization of disrupted intracellular environments resulting from ADAR2 downregulation may be a therapeutic target for ALS. We discuss the development of targeted therapy for ALS using the AR2 mouse model.
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Abstract
ALS is a relentless neurodegenerative disease in which motor neurons are the susceptible neuronal population. Their death results in progressive paresis of voluntary and respiratory muscles. The unprecedented rate of discoveries over the last two decades have broadened our knowledge of genetic causes and helped delineate molecular pathways. Here we critically review ALS epidemiology, genetics, pathogenic mechanisms, available animal models, and iPS cell technologies with a focus on their translational therapeutic potential. Despite limited clinical success in treatments to date, the new discoveries detailed here offer new models for uncovering disease mechanisms as well as novel strategies for intervention.
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