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Knorr S, Rauschenberger L, Muthuraman M, McFleder R, Ott T, Grundmann-Hauser K, Higuchi T, Volkmann J, Ip CW. Disturbed brain energy metabolism in a rodent model of DYT-TOR1A dystonia. Neurobiol Dis 2024; 194:106462. [PMID: 38442845 DOI: 10.1016/j.nbd.2024.106462] [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: 01/17/2024] [Revised: 02/21/2024] [Accepted: 03/01/2024] [Indexed: 03/07/2024] Open
Abstract
DYT-TOR1A (DYT1) dystonia, characterized by reduced penetrance and suspected environmental triggers, is explored using a "second hit" DYT-TOR1A rat model. We aim to investigate the biological mechanisms driving the conversion into a dystonic phenotype, focusing on the striatum's role in dystonia pathophysiology. Sciatic nerve crush injury was induced in ∆ETorA rats, lacking spontaneous motor abnormalities, and wild-type (wt) rats. Twelve weeks post-injury, unbiased RNA-sequencing was performed on the striatum to identify differentially expressed genes (DEGs) and pathways. Fenofibrate, a PPARα agonist, was introduced to assess its effects on gene expression. 18F-FDG autoradiography explored metabolic alterations in brain networks. Low transcriptomic variability existed between naïve wt and ∆ETorA rats (17 DEGs). Sciatic nerve injury significantly impacted ∆ETorA rats (1009 DEGs) compared to wt rats (216 DEGs). Pathway analyses revealed disruptions in energy metabolism, specifically in fatty acid β-oxidation and glucose metabolism. Fenofibrate induced gene expression changes in wt rats but failed in ∆ETorA rats. Fenofibrate increased dystonia-like movements in wt rats but reduced them in ∆ETorA rats. 18F-FDG autoradiography indicated modified glucose metabolism in motor and somatosensory cortices and striatum in both ∆ETorA and wt rats post-injury. Our findings highlight perturbed energy metabolism pathways in DYT-TOR1A dystonia, emphasizing compromised PPARα agonist efficacy in the striatum. Furthermore, we identify impaired glucose metabolism in the brain network, suggesting a potential shift in energy substrate utilization in dystonic DYT-TOR1A rats. These results contribute to understanding the pathophysiology and potential therapeutic targets for DYT-TOR1A dystonia.
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Affiliation(s)
- Susanne Knorr
- Department of Neurology, University Hospital Würzburg, 97080, Germany
| | | | | | - Rhonda McFleder
- Department of Neurology, University Hospital Würzburg, 97080, Germany
| | - Thomas Ott
- Institute for Medical Genetics and Applied Genomics, University of Tübingen, 72076, Germany; Core Facility Transgenic Animals, University Hospital of Tübingen, 72076, Germany; Max Planck Institute for Biological Cybernetics, Tübingen, 72076, Germany
| | - Kathrin Grundmann-Hauser
- Institute for Medical Genetics and Applied Genomics, University of Tübingen, 72076, Germany; Centre for Rare Diseases, University of Tübingen, 72076, Germany
| | - Takahiro Higuchi
- Department of Nuclear Medicine, University Hospital Würzburg, 97080, Germany
| | - Jens Volkmann
- Department of Neurology, University Hospital Würzburg, 97080, Germany
| | - Chi Wang Ip
- Department of Neurology, University Hospital Würzburg, 97080, Germany.
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2
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Gonzalez-Alegre P. Advances in molecular and cell biology of dystonia: Focus on torsinA. Neurobiol Dis 2019; 127:233-241. [DOI: 10.1016/j.nbd.2019.03.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 02/20/2019] [Accepted: 03/09/2019] [Indexed: 12/15/2022] Open
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3
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Dominguez Gonzalez B, Billion K, Rous S, Pavie B, Lange C, Goodchild R. Excess LINC complexes impair brain morphogenesis in a mouse model of recessive TOR1A disease. Hum Mol Genet 2019; 27:2154-2170. [PMID: 29868845 DOI: 10.1093/hmg/ddy125] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 04/06/2018] [Indexed: 01/08/2023] Open
Abstract
Heterozygosity for the TOR1A-Δgag mutation causes semi-penetrant childhood-onset dystonia (OMIM #128100). More recently, homozygous TOR1A mutations were shown to cause severe neurological dysfunction in infants. However, there is little known about the recessive cases, including whether existing reports define the full spectrum of recessive TOR1A disease. Here we describe abnormal brain morphogenesis in ∼30% of Tor1a-/- mouse embryos while, in contrast, this is not found in Tor1aΔgag/Δgag mice. The abnormal Tor1a-/- brains contain excess neural tissue, as well as proliferative zone cytoarchitectural defects related to radial glial cell polarity and cytoskeletal organization. In cultured cells torsinA effects the linker of nucleoskeleton and cytoskeleton (LINC) complex that couples the nucleus and cytoskeleton. Here we identify that torsinA loss elevates LINC complex levels in the proliferative zone, and that genetic reduction of LINC complexes prevents abnormal brain morphogenesis in Tor1a-/- embryos. These data show that Tor1a affects radial glial cells via a LINC complex mediated mechanism. They also predict human TOR1A disease will include incompletely penetrant defects in embryonic brain morphogenesis in cases where mutations ablate TOR1A function.
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Affiliation(s)
- Beatriz Dominguez Gonzalez
- VIB & KU Leuven Centre for Brain & Disease Research, Campus Gasthuisberg, 3000 Leuven, Belgium.,Department of Neurosciences, Campus Gasthuisberg, KU Leuven, 3000 Leuven, Belgium
| | - Karolien Billion
- VIB & KU Leuven Centre for Brain & Disease Research, Campus Gasthuisberg, 3000 Leuven, Belgium.,Department of Neurosciences, Campus Gasthuisberg, KU Leuven, 3000 Leuven, Belgium
| | - Stef Rous
- VIB & KU Leuven Centre for Brain & Disease Research, Campus Gasthuisberg, 3000 Leuven, Belgium.,Department of Neurosciences, Campus Gasthuisberg, KU Leuven, 3000 Leuven, Belgium
| | - Benjamin Pavie
- VIB & KU Leuven Centre for Brain & Disease Research, Campus Gasthuisberg, 3000 Leuven, Belgium.,VIB Bio Imaging Core, Campus Gasthuisberg, 3000 Leuven, Belgium
| | - Christian Lange
- DFG-Research Center and Cluster of Excellence for Regenerative Therapies (CRTD), Technische Universität Dresden, Fetscherstr. 105, D-01307, Dresden, Germany
| | - Rose Goodchild
- VIB & KU Leuven Centre for Brain & Disease Research, Campus Gasthuisberg, 3000 Leuven, Belgium.,Department of Neurosciences, Campus Gasthuisberg, KU Leuven, 3000 Leuven, Belgium
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4
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Pernigo S, Chegkazi MS, Yip YY, Treacy C, Glorani G, Hansen K, Politis A, Bui S, Dodding MP, Steiner RA. Structural basis for isoform-specific kinesin-1 recognition of Y-acidic cargo adaptors. eLife 2018; 7:38362. [PMID: 30320553 PMCID: PMC6214655 DOI: 10.7554/elife.38362] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 10/14/2018] [Indexed: 12/19/2022] Open
Abstract
The light chains (KLCs) of the heterotetrameric microtubule motor kinesin-1, that bind to cargo adaptor proteins and regulate its activity, have a capacity to recognize short peptides via their tetratricopeptide repeat domains (KLCTPR). Here, using X-ray crystallography, we show how kinesin-1 recognizes a novel class of adaptor motifs that we call ‘Y-acidic’ (tyrosine flanked by acidic residues), in a KLC-isoform specific manner. Binding specificities of Y-acidic motifs (present in JIP1 and in TorsinA) to KLC1TPR are distinct from those utilized for the recognition of W-acidic motifs found in adaptors that are KLC- isoform non-selective. However, a partial overlap on their receptor binding sites implies that adaptors relying on Y-acidic and W-acidic motifs must act independently. We propose a model to explain why these two classes of motifs that bind to the concave surface of KLCTPR with similar low micromolar affinity can exhibit different capacities to promote kinesin-1 activity.
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Affiliation(s)
- Stefano Pernigo
- Randall Centre of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Magda S Chegkazi
- Randall Centre of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Yan Y Yip
- Randall Centre of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Conor Treacy
- Randall Centre of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Giulia Glorani
- Randall Centre of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Kjetil Hansen
- Department of Chemistry, King's College London, London, United Kingdom
| | - Argyris Politis
- Department of Chemistry, King's College London, London, United Kingdom
| | - Soi Bui
- Randall Centre of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Mark P Dodding
- Randall Centre of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom.,School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Roberto A Steiner
- Randall Centre of Cell and Molecular Biophysics, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
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5
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Nguyen TQ, Aumont-Nicaise M, Andreani J, Velours C, Chenon M, Vilela F, Geneste C, Varela PF, Llinas P, Ménétrey J. Characterization of the binding mode of JNK-interacting protein 1 (JIP1) to kinesin-light chain 1 (KLC1). J Biol Chem 2018; 293:13946-13960. [PMID: 30026235 PMCID: PMC6130945 DOI: 10.1074/jbc.ra118.003916] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/17/2018] [Indexed: 01/05/2023] Open
Abstract
JIP1 was first identified as scaffold protein for the MAP kinase JNK and is a cargo protein for the kinesin1 molecular motor. JIP1 plays significant and broad roles in neurons, mainly as a regulator of kinesin1-dependent transport, and is associated with human pathologies such as cancer and Alzheimer disease. JIP1 is specifically recruited by the kinesin-light chain 1 (KLC1) of kinesin1, but the details of this interaction are not yet fully elucidated. Here, using calorimetry, we extensively biochemically characterized the interaction between KLC1 and JIP1. Using various truncated fragments of the tetratricopeptide repeat (TPR) domain of KLC1, we narrowed down its JIP1-binding region and identified seven KLC1 residues critical for JIP1 binding. These isothermal titration calorimetry (ITC)-based binding data enabled us to footprint the JIP1-binding site on KLC1-TPR. This footprint was used to uncover the structural basis for the marginal inhibition of JIP1 binding by the autoinhibitory LFP-acidic motif of KLC1, as well as for the competition between JIP1 and another cargo protein of kinesin1, the W-acidic motif-containing alcadein-α. Also, we examined the role of each of these critical residues of KLC1 for JIP1 binding in light of the previously reported crystal structure of the KLC1-TPR:JIP1 complex. Finally, sequence search in eukaryotic genomes identified several proteins, among which is SH2D6, that exhibit a motif similar to the KLC1-binding motif of JIP1. Overall, our extensive biochemical characterization of the KLC:JIP1 interaction, as well as identification of potential KLC1-binding partners, improves the understanding of how this growing family of cargos is recruited to kinesin1 by KLC1.
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Affiliation(s)
- T Quyen Nguyen
- From the Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France and
- the Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Magali Aumont-Nicaise
- the Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Jessica Andreani
- the Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Christophe Velours
- From the Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France and
- the Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Mélanie Chenon
- From the Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France and
- the Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Fernando Vilela
- From the Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France and
- the Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Clémentine Geneste
- the Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Paloma F Varela
- From the Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France and
- the Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Paola Llinas
- From the Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France and
- the Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Julie Ménétrey
- From the Laboratoire d'Enzymologie et Biochimie Structurales (LEBS), CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France and
- the Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
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6
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Human TorsinA can function in the yeast cytosol as a molecular chaperone. Biochem J 2017; 474:3439-3454. [PMID: 28871039 PMCID: PMC5628414 DOI: 10.1042/bcj20170395] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 08/25/2017] [Accepted: 09/01/2017] [Indexed: 11/17/2022]
Abstract
TorsinA (TorA) is an AAA+ (ATPases associated with diverse cellular activities) ATPase linked to dystonia type 1 (DYT1), a neurological disorder that leads to uncontrollable muscular movements. Although DYT1 is linked to a 3 bp deletion in the C-terminus of TorA, the biological function of TorA remains to be established. Here, we use the yeast Saccharomyces cerevisiae as a tractable in vivo model to explore TorA function. We demonstrate that TorA can protect yeast cells against different forms of environmental stress and show that in the absence of the molecular disaggregase Hsp104, TorA can refold heat-denatured luciferase in vivo in an ATP-dependent manner. However, this activity requires TorA to be translocated to the cytoplasm from the endoplasmic reticulum in order to access and process cytoplasmic protein aggregates. Furthermore, mutational or chemical inactivation of the ATPase activity of TorA blocks this activity. We also find that TorA can inhibit the propagation of certain conformational variants of [PSI+], the aggregated prion form of the endogenous Sup35 protein. Finally, we show that while cellular localisation remains unchanged in the dystonia-linked TorA mutant ΔE302-303, the ability of this mutant form of TorA to protect against cellular stress and to facilitate protein refolding is impaired, consistent with it being a loss-of-function mutation.
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7
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Zacchi LF, Dittmar JC, Mihalevic MJ, Shewan AM, Schulz BL, Brodsky JL, Bernstein KA. Early-onset torsion dystonia: a novel high-throughput yeast genetic screen for factors modifying protein levels of torsinAΔE. Dis Model Mech 2017; 10:1129-1140. [PMID: 28768697 PMCID: PMC5611967 DOI: 10.1242/dmm.029926] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 07/18/2017] [Indexed: 12/12/2022] Open
Abstract
Dystonia is the third most common movement disorder, but its diagnosis and treatment remain challenging. One of the most severe types of dystonia is early-onset torsion dystonia (EOTD). The best studied and validated EOTD-associated mutation, torsinAΔE, is a deletion of a C-terminal glutamate residue in the AAA+ ATPase torsinA. TorsinA appears to be an endoplasmic reticulum (ER)/nuclear envelope chaperone with multiple roles in the secretory pathway and in determining subcellular architecture. Many functions are disabled in the torsinAΔE variant, and torsinAΔE is also less stable than wild-type torsinA and is a substrate for ER-associated degradation. Nevertheless, the molecular factors involved in the biogenesis and degradation of torsinA and torsinAΔE have not been fully explored. To identify conserved cellular factors that can alter torsinAΔE protein levels, we designed a new high-throughput, automated, genome-wide screen utilizing our validated Saccharomyces cerevisiae torsinA expression system. By analyzing the yeast non-essential gene deletion collection, we identified 365 deletion strains with altered torsinAΔE steady-state levels. One notable hit was EUG1, which encodes a member of the protein disulfide isomerase family (PDIs). PDIs reside in the ER and catalyze the formation of disulfide bonds, mediate protein quality control and aid in nascent protein folding. We validated the role of select human PDIs in torsinA biogenesis in mammalian cells and found that overexpression of PDIs reduced the levels of torsinA and torsinAΔE. Together, our data report the first genome-wide screen to identify cellular factors that alter expression levels of the EOTD-associated protein torsinAΔE. More generally, the identified hits help in dissecting the cellular machinery involved in folding and degrading a torsinA variant, and constitute potential therapeutic factors for EOTD. This screen can also be readily adapted to identify factors impacting the levels of any protein of interest, considerably expanding the applicability of yeast in both basic and applied research.
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Affiliation(s)
- Lucía F Zacchi
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - John C Dittmar
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Michael J Mihalevic
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 5117 Centre Avenue, UPCI Research Pavilion, 2.42e, Pittsburgh, PA 15213, USA
| | - Annette M Shewan
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Benjamin L Schulz
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Jeffrey L Brodsky
- Department of Biological Sciences, A320 Langley Hall, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Kara A Bernstein
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 5117 Centre Avenue, UPCI Research Pavilion, 2.42e, Pittsburgh, PA 15213, USA
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8
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Cascalho A, Jacquemyn J, Goodchild RE. Membrane defects and genetic redundancy: Are we at a turning point for DYT1 dystonia? Mov Disord 2016; 32:371-381. [PMID: 27911022 DOI: 10.1002/mds.26880] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/24/2016] [Accepted: 10/29/2016] [Indexed: 12/11/2022] Open
Abstract
Heterozygosity for a 3-base pair deletion (ΔGAG) in TOR1A/torsinA is one of the most common causes of hereditary dystonia. In this review, we highlight current understanding of how this mutation causes disease from research spanning structural biochemistry, cell science, neurobiology, and several model organisms. We now know that homozygosity for ΔGAG has the same effects as Tor1aKO , implicating a partial loss of function mechanism in the ΔGAG/+ disease state. In addition, torsinA loss specifically affects neurons in mice, even though the gene is broadly expressed, apparently because of differential expression of homologous torsinB. Furthermore, certain neuronal subtypes are more severely affected by torsinA loss. Interestingly, these include striatal cholinergic interneurons that display abnormal responses to dopamine in several Tor1a animal models. There is also progress on understanding torsinA molecular cell biology. The structural basis of how ΔGAG inhibits torsinA ATPase activity is defined, although mutant torsinAΔGAG protein also displays some characteristics suggesting it contributes to dystonia by a gain-of-function mechanism. Furthermore, a consistent relationship is emerging between torsin dysfunction and membrane biology, including an evolutionarily conserved regulation of lipid metabolism. Considered together, these findings provide major advances toward understanding the molecular, cellular, and neurobiological pathologies of DYT1/TOR1A dystonia that can hopefully be exploited for new approaches to treat this disease. © 2016 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Ana Cascalho
- Vlaams Instituut voor Biotechnologie Centre for the Biology of Disease, Leuven, Belgium.,KU Leuven, Department of Human Genetics, Leuven, Belgium
| | - Julie Jacquemyn
- Vlaams Instituut voor Biotechnologie Centre for the Biology of Disease, Leuven, Belgium.,KU Leuven, Department of Human Genetics, Leuven, Belgium
| | - Rose E Goodchild
- Vlaams Instituut voor Biotechnologie Centre for the Biology of Disease, Leuven, Belgium.,KU Leuven, Department of Human Genetics, Leuven, Belgium
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9
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Abstract
Torsin ATPases (Torsins) belong to the widespread AAA+ (ATPases associated with a variety of cellular activities) family of ATPases, which share structural similarity but have diverse cellular functions. Torsins are outliers in this family because they lack many characteristics of typical AAA+ proteins, and they are the only members of the AAA+ family located in the endoplasmic reticulum and contiguous perinuclear space. While it is clear that Torsins have essential roles in many, if not all metazoans, their precise cellular functions remain elusive. Studying Torsins has significant medical relevance since mutations in Torsins or Torsin-associated proteins result in a variety of congenital human disorders, the most frequent of which is early-onset torsion (DYT1) dystonia, a severe movement disorder. A better understanding of the Torsin system is needed to define the molecular etiology of these diseases, potentially enabling corrective therapy. Here, we provide a comprehensive overview of the Torsin system in metazoans, discuss functional clues obtained from various model systems and organisms and provide a phylogenetic and structural analysis of Torsins and their regulatory cofactors in relation to disease-causative mutations. Moreover, we review recent data that have led to a dramatically improved understanding of these machines at a molecular level, providing a foundation for investigating the molecular defects underlying the associated movement disorders. Lastly, we discuss our ideas on how recent progress may be utilized to inform future studies aimed at determining the cellular role(s) of these atypical molecular machines and their implications for dystonia treatment options.
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Affiliation(s)
- April E Rose
- a Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , CT , USA and
| | - Rebecca S H Brown
- a Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , CT , USA and
| | - Christian Schlieker
- a Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , CT , USA and.,b Department of Cell Biology , Yale School of Medicine , New Haven , CT , USA
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10
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Cerebellar synaptogenesis is compromised in mouse models of DYT1 dystonia. Exp Neurol 2015; 271:457-67. [DOI: 10.1016/j.expneurol.2015.07.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 07/01/2015] [Accepted: 07/07/2015] [Indexed: 12/16/2022]
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11
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Kim AY, Seo JB, Kim WT, Choi HJ, Kim SY, Morrow G, Tanguay RM, Steller H, Koh YH. The pathogenic human Torsin A in Drosophila activates the unfolded protein response and increases susceptibility to oxidative stress. BMC Genomics 2015; 16:338. [PMID: 25903460 PMCID: PMC4415242 DOI: 10.1186/s12864-015-1518-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Accepted: 04/10/2015] [Indexed: 01/11/2023] Open
Abstract
Background Dystonia1 (DYT1) dystonia is caused by a glutamic acid deletion (ΔE) mutation in the gene encoding Torsin A in humans (HTorA). To investigate the unknown molecular and cellular mechanisms underlying DYT1 dystonia, we performed an unbiased proteomic analysis. Results We found that the amount of proteins and transcripts of an Endoplasmic reticulum (ER) resident chaperone Heat shock protein cognate 3 (HSC3) and a mitochondria chaperone Heat Shock Protein 22 (HSP22) were significantly increased in the HTorAΔE– expressing brains compared to the normal HTorA (HTorAWT) expressing brains. The physiological consequences included an increased susceptibility to oxidative and ER stress compared to normal HTorAWT flies. The alteration of transcripts of Inositol-requiring enzyme-1 (IRE1)-dependent spliced X box binding protein 1(Xbp1), several ER chaperones, a nucleotide exchange factor, Autophagy related protein 8b (ATG8b) and components of the ER associated degradation (ERAD) pathway and increased expression of the Xbp1-enhanced Green Fluorescence Protein (eGFP) in HTorAΔE brains strongly indicated the activation of the unfolded protein response (UPR). In addition, perturbed expression of the UPR sensors and inducers in the HTorAΔEDrosophila brains resulted in a significantly reduced life span of the flies. Furthermore, the types and quantities of proteins present in the anti-HSC3 positive microsomes in the HTorAΔE brains were different from those of the HTorAWT brains. Conclusion Taken together, these data show that HTorAΔE in Drosophila brains may activate the UPR and increase the expression of HSP22 to compensate for the toxic effects caused by HTorAΔE in the brains. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1518-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- A-Young Kim
- ILSONG Institute of Life Science, Hallym University, 1605-4 Gwanyangdong, Dongan-gu, Anyang, Gyeonggido, 431-060, Republic of Korea. .,Department of Biomedical Gerontology, Graduate School of Hallym University, Chuncheon, Gangwon-do, 200-702, Republic of Korea.
| | - Jong Bok Seo
- Korea Basic Science Institute, Sungbuk-gu, Seoul, 136-713, Republic of Korea.
| | - Won-Tae Kim
- National Academy of Agricultural Science, Rural Development Administration, Suwon, 441-707, Republic of Korea.
| | - Hee Jeong Choi
- ILSONG Institute of Life Science, Hallym University, 1605-4 Gwanyangdong, Dongan-gu, Anyang, Gyeonggido, 431-060, Republic of Korea. .,Department of Biomedical Gerontology, Graduate School of Hallym University, Chuncheon, Gangwon-do, 200-702, Republic of Korea.
| | - Soo-Young Kim
- Korea Basic Science Institute, Sungbuk-gu, Seoul, 136-713, Republic of Korea.
| | - Genevieve Morrow
- Department of Molecular Biology, Medical Biochemistry & Pathology, Université Laval, Québec, Qc, G1V 0A6, Canada.
| | - Robert M Tanguay
- Department of Molecular Biology, Medical Biochemistry & Pathology, Université Laval, Québec, Qc, G1V 0A6, Canada.
| | - Hermann Steller
- Howard Hughes Medical Institute, the Rockefeller University, New York, NY, 10065, USA.
| | - Young Ho Koh
- ILSONG Institute of Life Science, Hallym University, 1605-4 Gwanyangdong, Dongan-gu, Anyang, Gyeonggido, 431-060, Republic of Korea. .,Department of Biomedical Gerontology, Graduate School of Hallym University, Chuncheon, Gangwon-do, 200-702, Republic of Korea.
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12
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LeDoux MS. Dystonia. Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00024-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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13
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Harata NC. Current Gaps in the Understanding of the Subcellular Distribution of Exogenous and Endogenous Protein TorsinA. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2014; 4:260. [PMID: 25279252 PMCID: PMC4175402 DOI: 10.7916/d8js9nr2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Accepted: 08/25/2014] [Indexed: 12/01/2022]
Abstract
Background An in-frame deletion leading to the loss of a single glutamic acid residue in the protein torsinA (ΔE-torsinA) results in an inherited movement disorder, DYT1 dystonia. This autosomal dominant disease affects the function of the brain without causing neurodegeneration, by a mechanism that remains unknown. Methods We evaluated the literature regarding the subcellular localization of torsinA. Results Efforts to elucidate the pathophysiological basis of DYT1 dystonia have relied partly on examining the subcellular distribution of the wild-type and mutated proteins. A typical approach is to introduce the human torsinA gene (TOR1A) into host cells and overexpress the protein therein. In both neurons and non-neuronal cells, exogenous wild-type torsinA introduced in this manner has been found to localize mainly to the endoplasmic reticulum, whereas exogenous ΔE-torsinA is predominantly in the nuclear envelope or cytoplasmic inclusions. Although these outcomes are relatively consistent, findings for the localization of endogenous torsinA have been variable, leaving its physiological distribution a matter of debate. Discussion As patients’ cells do not overexpress torsinA proteins, it is important to understand why the reported distributions of the endogenous proteins are inconsistent. We propose that careful optimization of experimental methods will be critical in addressing the causes of the differences among the distributions of endogenous (non-overexpressed) vs. exogenously introduced (overexpressed) proteins.
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Affiliation(s)
- N Charles Harata
- Department of Molecular Physiology & Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
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Koh JY, Iwabuchi S, Harata NC. Dystonia-associated protein torsinA is not detectable at the nerve terminals of central neurons. Neuroscience 2013; 253:316-29. [PMID: 24025868 DOI: 10.1016/j.neuroscience.2013.08.060] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/28/2013] [Accepted: 08/28/2013] [Indexed: 01/23/2023]
Abstract
Presynaptic functions of the mammalian central neurons are regulated by a network of protein interactions. Synaptic vesicle recycling in and neurotransmitter release from the presynaptic nerve terminals are altered when a glutamate-deleting mutation is present in the torsinA protein (ΔE-torsinA). This mutation is linked with a hereditary form of the movement disorder dystonia known as DYT1 dystonia. Although torsinA expression is prevalent throughout the central nervous system, its subcellular localization - in particular with respect to presynaptic nerve terminals - remains unclear. This information would be useful in narrowing down possible models for how wild-type torsinA affects presynaptic function, as well as the nature of the presynaptic dysfunction that arises in the context of ΔE-torsinA mutation. Here we report on an analysis of the presynaptic localization of torsinA in cultured neurons obtained from a knock-in mouse model of DYT1 dystonia. Primary cultures of neurons were established from heterozygous and homozygous ΔE-torsinA knock-in mice, as well as from their wild-type littermates. Neurons were obtained from the striatum, cerebral cortex and hippocampus of these mice, and were subjected to immunocytochemistry. This analysis revealed the expression of both proteins in the somata and dendrites. However, neither the nerve terminals nor axonal shafts were immunoreactive. These results were confirmed by fluorogram-based quantitation. Our findings indicate that neither the wild-type nor the ΔE-torsinA mutant protein is present at substantial levels in the presynaptic structures of cultured neurons. Thus, the effects of torsinA, in wild-type and mutant forms, appear to influence presynaptic function indirectly, without residing in presynaptic structures.
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Affiliation(s)
- J-Y Koh
- Department of Molecular Physiology & Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, USA
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15
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Kawarai T, Miyamoto R, Murakami N, Miyazaki Y, Koizumi H, Sako W, Mukai Y, Sato K, Matsumoto S, Sakamoto T, Izumi Y, Kaji R. [Dystonia genes and elucidation of their roles in dystonia pathogenesis]. Rinsho Shinkeigaku 2013; 53:419-29. [PMID: 23782819 DOI: 10.5692/clinicalneurol.53.419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Identification of causative genes for hereditary dystonia and elucidation of their functions are crucial for better understanding of dystonia pathogenesis. As seen in other hereditary neurologic disorders, intra- and inter-familial clinical variations have been demonstrated in hereditary dystonia. Asymptomatic carriers can be found due to alterations in penetrance, generally reduced in succeeding generations. Current known dystonia genes include those related to dopamine metabolism, transcription factor, cytoskeleton, transport of glucose and sodium ion, etc. It has been reported that effects of deep brain stimulation can vary significantly depending on genotype. Accumulation of genotype-outcome correlations would contribute to treatment decisions for dystonia patients.
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Affiliation(s)
- Toshitaka Kawarai
- Department of Clinical Neuroscience Institute of Health Biosciences, Graduate School of Medicine, University of Tokushima
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Puglisi F, Vanni V, Ponterio G, Tassone A, Sciamanna G, Bonsi P, Pisani A, Mandolesi G. Torsin A Localization in the Mouse Cerebellar Synaptic Circuitry. PLoS One 2013; 8:e68063. [PMID: 23840813 PMCID: PMC3686744 DOI: 10.1371/journal.pone.0068063] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/24/2013] [Indexed: 11/19/2022] Open
Abstract
Torsin A (TA) is a ubiquitous protein belonging to the superfamily of proteins called "ATPases associated with a variety of cellular activities" (AAA(+) ATPase). To date, a great deal of attention has been focused on neuronal TA since its mutant form causes early-onset (DYT1) torsion dystonia, an inherited movement disorder characterized by sustained muscle contractions and abnormal postures. Interestingly, it has been proposed that TA, by interacting with the cytoskeletal network, may contribute to the control of neurite outgrowth and/or by acting as a chaperone at synapses could affect synaptic vesicle turnover and neurotransmitter release. Accordingly, both its peculiar developmental expression in striatum and cerebellum and evidence from DYT1 knock-in mice suggest that TA may influence dendritic arborization and synaptogenesis in the brain. Therefore, to better understand TA function a detailed description of its localization at synaptic level is required. Here, we characterized by means of rigorous quantitative confocal analysis TA distribution in the mouse cerebellum at postnatal day 14 (P14), when both cerebellar synaptogenesis and TA expression peak. We observed that the protein is broadly distributed both in cerebellar cortex and in the deep cerebellar nuclei (DCN). Of note, Purkinje cells (PC) express high levels of TA also in the spines and axonal terminals. In addition, abundant expression of the protein was found in the main GABA-ergic and glutamatergic inputs of the cerebellar cortex. Finally, TA was observed also in glial cells, a cellular population little explored so far. These results extend our knowledge on TA synaptic localization providing a clue to its potential role in synaptic development.
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Affiliation(s)
- Francesca Puglisi
- Department of Systems Medicine, University of Rome Tor Vergata/Laboratory of Neurophysiology and Synaptic Plasticity, Fondazione Santa Lucia, Rome, Italy
| | - Valentina Vanni
- Department of Systems Medicine, University of Rome Tor Vergata/Laboratory of Neurophysiology and Synaptic Plasticity, Fondazione Santa Lucia, Rome, Italy
| | - Giulia Ponterio
- Department of Systems Medicine, University of Rome Tor Vergata/Laboratory of Neurophysiology and Synaptic Plasticity, Fondazione Santa Lucia, Rome, Italy
| | - Annalisa Tassone
- Department of Systems Medicine, University of Rome Tor Vergata/Laboratory of Neurophysiology and Synaptic Plasticity, Fondazione Santa Lucia, Rome, Italy
| | - Giuseppe Sciamanna
- Department of Systems Medicine, University of Rome Tor Vergata/Laboratory of Neurophysiology and Synaptic Plasticity, Fondazione Santa Lucia, Rome, Italy
| | - Paola Bonsi
- Department of Systems Medicine, University of Rome Tor Vergata/Laboratory of Neurophysiology and Synaptic Plasticity, Fondazione Santa Lucia, Rome, Italy
| | - Antonio Pisani
- Department of Systems Medicine, University of Rome Tor Vergata/Laboratory of Neurophysiology and Synaptic Plasticity, Fondazione Santa Lucia, Rome, Italy
- * E-mail:
| | - Georgia Mandolesi
- Department of Systems Medicine, University of Rome Tor Vergata/Laboratory of Neurophysiology and Synaptic Plasticity, Fondazione Santa Lucia, Rome, Italy
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Lohmann K, Wilcox RA, Winkler S, Ramirez A, Rakovic A, Park JS, Arns B, Lohnau T, Groen J, Kasten M, Brüggemann N, Hagenah J, Schmidt A, Kaiser FJ, Kumar KR, Zschiedrich K, Alvarez-Fischer D, Altenmüller E, Ferbert A, Lang AE, Münchau A, Kostic V, Simonyan K, Agzarian M, Ozelius LJ, Langeveld APM, Sue CM, Tijssen MAJ, Klein C. Whispering dysphonia (DYT4 dystonia) is caused by a mutation in the TUBB4 gene. Ann Neurol 2013; 73:537-45. [PMID: 23595291 DOI: 10.1002/ana.23829] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 11/13/2012] [Accepted: 11/30/2012] [Indexed: 12/19/2022]
Abstract
OBJECTIVE A study was undertaken to identify the gene underlying DYT4 dystonia, a dominantly inherited form of spasmodic dysphonia combined with other focal or generalized dystonia and a characteristic facies and body habitus, in an Australian family. METHODS Genome-wide linkage analysis was carried out in 14 family members followed by genome sequencing in 2 individuals. The index patient underwent a detailed neurological follow-up examination, including electrophysiological studies and magnetic resonance imaging scanning. Biopsies of the skin and olfactory mucosa were obtained, and expression levels of TUBB4 mRNA were determined by quantitative real-time polymerase chain reaction in 3 different cell types. All exons of TUBB4 were screened for mutations in 394 unrelated dystonia patients. RESULTS The disease-causing gene was mapped to a 23cM region on chromosome 19p13.3-p13.2 with a maximum multipoint LOD score of 5.338 at markers D9S427 and D9S1034. Genome sequencing revealed a missense variant in the TUBB4 (tubulin beta-4; Arg2Gly) gene as the likely cause of disease. Sequencing of TUBB4 in 394 unrelated dystonia patients revealed another missense variant (Ala271Thr) in a familial case of segmental dystonia with spasmodic dysphonia. mRNA expression studies demonstrated significantly reduced levels of mutant TUBB4 mRNA in different cell types from a heterozygous Arg2Gly mutation carrier compared to controls. INTERPRETATION A mutation in TUBB4 causes DYT4 dystonia in this Australian family with so-called whispering dysphonia, and other mutations in TUBB4 may contribute to spasmodic dysphonia. Given that TUBB4 is a neuronally expressed tubulin, our results imply abnormal microtubule function as a novel mechanism in the pathophysiology of dystonia.
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Affiliation(s)
- Katja Lohmann
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
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Abstract
Dystonia has been defined as a syndrome of involuntary, sustained muscle contractions affecting one or more sites of the body, frequently causing twisting and repetitive movements or abnormal postures. Dystonia is also a clinical sign that can be the presenting or prominent manifestation of many neurodegenerative and neurometabolic disorders. Etiological categories include primary dystonia, secondary dystonia, heredodegenerative diseases with dystonia, and dystonia plus. Primary dystonia includes syndromes in which dystonia is the sole phenotypic manifestation with the exception that tremor can be present as well. Most primary dystonia begins in adults, and approximately 10% of probands report one or more affected family members. Many cases of childhood- and adolescent-onset dystonia are due to mutations in TOR1A and THAP1. Mutations in THAP1 and CIZ1 have been associated with sporadic and familial adult-onset dystonia. Although significant recent progress had been made in defining the genetic basis for most of the dystonia-plus and heredodegenerative diseases with dystonia, a major gap remains in understanding the genetic etiologies for most cases of adult-onset primary dystonia. Common themes in the cellular biology of dystonia include G1/S cell cycle control, monoaminergic neurotransmission, mitochondrial dysfunction, and the neuronal stress response.
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Affiliation(s)
- Mark S LeDoux
- Department of Neurology, University of Tennessee Health Science Center, Memphis, TN, USA
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19
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Untethering the nuclear envelope and cytoskeleton: biologically distinct dystonias arising from a common cellular dysfunction. Int J Cell Biol 2012; 2012:634214. [PMID: 22611399 PMCID: PMC3352338 DOI: 10.1155/2012/634214] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 12/12/2011] [Accepted: 01/08/2012] [Indexed: 12/31/2022] Open
Abstract
Most cases of early onset DYT1 dystonia in humans are caused by a GAG deletion in the TOR1A gene leading to loss of a glutamic acid (ΔE) in the torsinA protein, which underlies a movement disorder associated with neuronal dysfunction without apparent neurodegeneration. Mutation/deletion of the gene (Dst) encoding dystonin in mice results in a dystonic movement disorder termed dystonia musculorum, which resembles aspects of dystonia in humans. While torsinA and dystonin proteins do not share modular domain architecture, they participate in a similar function by modulating a structural link between the nuclear envelope and the cytoskeleton in neuronal cells. We suggest that through a shared interaction with the nuclear envelope protein nesprin-3α, torsinA and the neuronal dystonin-a2 isoform comprise a bridge complex between the outer nuclear membrane and the cytoskeleton, which is critical for some aspects of neuronal development and function. Elucidation of the overlapping roles of torsinA and dystonin-a2 in nuclear/endoplasmic reticulum dynamics should provide insights into the cellular mechanisms underlying the dystonic phenotype.
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20
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Zhu H, Lee HY, Tong Y, Hong BS, Kim KP, Shen Y, Lim KJ, Mackenzie F, Tempel W, Park HW. Crystal structures of the tetratricopeptide repeat domains of kinesin light chains: insight into cargo recognition mechanisms. PLoS One 2012; 7:e33943. [PMID: 22470497 PMCID: PMC3314626 DOI: 10.1371/journal.pone.0033943] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 02/23/2012] [Indexed: 01/07/2023] Open
Abstract
Kinesin-1 transports various cargos along the axon by interacting with the cargos through its light chain subunit. Kinesin light chains (KLC) utilize its tetratricopeptide repeat (TPR) domain to interact with over 10 different cargos. Despite a high sequence identity between their TPR domains (87%), KLC1 and KLC2 isoforms exhibit differential binding properties towards some cargos. We determined the structures of human KLC1 and KLC2 tetratricopeptide repeat (TPR) domains using X-ray crystallography and investigated the different mechanisms by which KLCs interact with their cargos. Using isothermal titration calorimetry, we attributed the specific interaction between KLC1 and JNK-interacting protein 1 (JIP1) cargo to residue N343 in the fourth TRP repeat. Structurally, the N343 residue is adjacent to other asparagines and lysines, creating a positively charged polar patch within the groove of the TPR domain. Whereas, KLC2 with the corresponding residue S328 did not interact with JIP1. Based on these finding, we propose that N343 of KLC1 can form "a carboxylate clamp" with its neighboring asparagine to interact with JIP1, similar to that of HSP70/HSP90 organizing protein-1's (HOP1) interaction with heat shock proteins. For the binding of cargos shared by KLC1 and KLC2, we propose a different site located within the groove but not involving N343. We further propose a third binding site on KLC1 which involves a stretch of polar residues along the inter-TPR loops that may form a network of hydrogen bonds to JIP3 and JIP4. Together, these results provide structural insights into possible mechanisms of interaction between KLC TPR domains and various cargo proteins.
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Affiliation(s)
- Haizhong Zhu
- Structural Genomics Consortium, Toronto, Ontario, Canada
| | - Han Youl Lee
- Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada
| | - Yufeng Tong
- Structural Genomics Consortium, Toronto, Ontario, Canada
| | - Bum-Soo Hong
- Structural Genomics Consortium, Toronto, Ontario, Canada
| | - Kyung-Phil Kim
- Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada
| | - Yang Shen
- Structural Genomics Consortium, Toronto, Ontario, Canada
| | - Kyung Jik Lim
- Philip Pocock Catholic Secondary School, Mississauga, Ontario, Canada
| | | | - Wolfram Tempel
- Structural Genomics Consortium, Toronto, Ontario, Canada
| | - Hee-Won Park
- Structural Genomics Consortium, Toronto, Ontario, Canada
- Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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21
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Abstract
The last 25 years have seen remarkable advances in our understanding of the genetic etiologies of dystonia, new approaches into dissecting underlying pathophysiology, and independent progress in identifying effective treatments. In this review we highlight some of these advances, especially the genetic findings that have taken us from phenomenological to molecular-based diagnoses. Twenty DYT loci have been designated and 10 genes identified, all based on linkage analyses in families. Hand in hand with these genetic findings, neurophysiological and imaging techniques have been employed that have helped illuminate the similarities and differences among the various etiological dystonia subtypes. This knowledge is just beginning to yield new approaches to treatment including those based on DYT1 animal models. Despite the lag in identifying genetically based therapies, effective treatments, including impressive benefits from deep brain stimulation and botulinum toxin chemodenervation, have marked the last 25 years. The challenge ahead includes continued advancement into understanding dystonia's many underlying causes and associated pathology and using this knowledge to advance treatment including preventing genetic disease expression.
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Affiliation(s)
- Laurie J Ozelius
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, New York, USA
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22
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Zhang L, Yokoi F, Jin YH, DeAndrade MP, Hashimoto K, Standaert DG, Li Y. Altered dendritic morphology of Purkinje cells in Dyt1 ΔGAG knock-in and purkinje cell-specific Dyt1 conditional knockout mice. PLoS One 2011; 6:e18357. [PMID: 21479250 PMCID: PMC3066238 DOI: 10.1371/journal.pone.0018357] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2011] [Accepted: 02/28/2011] [Indexed: 11/18/2022] Open
Abstract
Background DYT1 early-onset generalized dystonia is a neurological movement disorder characterized by involuntary muscle contractions. It is caused by a trinucleotide deletion of a GAG (ΔGAG) in the DYT1 (TOR1A) gene encoding torsinA; the mouse homolog of this gene is Dyt1 (Tor1a). Although structural and functional alterations in the cerebellum have been reported in DYT1 dystonia, neuronal morphology has not been examined in vivo. Methodology/Principal Findings In this study, we examined the morphology of the cerebellum in Dyt1 ΔGAG knock-in (KI) mice. Golgi staining of the cerebellum revealed a reduction in the length of primary dendrites and a decrease in the number of spines on the distal dendrites of Purkinje cells. To determine if this phenomenon was cell autonomous and mediated by a loss of torsinA function in Purkinje cells, we created a knockout of the Dyt1 gene only in Purkinje cells of mice. We found the Purkinje-cell specific Dyt1 conditional knockout (Dyt1 pKO) mice have similar alterations in Purkinje cell morphology, with shortened primary dendrites and decreased spines on the distal dendrites. Conclusion/Significance These results suggest that the torsinA is important for the proper development of the cerebellum and a loss of this function in the Purkinje cells results in an alteration in dendritic structure.
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Affiliation(s)
- Lin Zhang
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Fumiaki Yokoi
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Yuan-Hu Jin
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Mark P. DeAndrade
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| | - David G. Standaert
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Yuqing Li
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail:
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23
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Genetics and Pharmacological Treatment of Dystonia. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2011. [DOI: 10.1016/b978-0-12-381328-2.00019-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Ezquerra M, Compta Y, Marti MJ. Identifying the genetic components underlying the pathophysiology of movement disorders. APPLICATION OF CLINICAL GENETICS 2011; 4:81-92. [PMID: 23776369 PMCID: PMC3681180 DOI: 10.2147/tacg.s7333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Movement disorders are a heterogeneous group of neurological conditions, few of which have been classically described as bona fide hereditary illnesses (Huntington’s chorea, for instance). Most are considered to be either sporadic or to feature varying degrees of familial aggregation (parkinsonism and dystonia). In the late twentieth century, Mendelian monogenic mutations were found for movement disorders with a clear and consistent family history. Although important, these findings apply only to very rare forms of movement disorders. Already in the twenty-first century, and taking advantage of the modern developments in genetics and molecular biology, growing attention is being paid to the complex genetics of movement disorders. The search for risk genetic variants (polymorphisms) in large cohorts and the identification of different risk variants across different populations and ethnic groups are under way, with the most relevant findings to date corresponding to recent genome wide association studies in Parkinson’s disease. These new approaches focusing on risk variants may enable the design of screening tests for early or even preclinical disease, and the identification of likely therapeutic targets.
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Affiliation(s)
- Mario Ezquerra
- Parkinson's Disease and Movement Disorders Unit, Service of Neurology, Institute of Clinical Neurosciences, Hospital Clinic of Barcelona, IDIBAPS, CIBERNED, Spain
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25
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Genetic and clinical features of primary torsion dystonia. Neurobiol Dis 2010; 42:127-35. [PMID: 21168499 DOI: 10.1016/j.nbd.2010.12.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 12/08/2010] [Accepted: 12/10/2010] [Indexed: 12/31/2022] Open
Abstract
Primary torsion dystonia (PTD) is defined as a syndrome in which dystonia is the only clinical sign (except for tremor), and there is no evidence of neuronal degeneration or an acquired cause by history or routine laboratory assessment. Seven different loci have been recognized for PTD but only two of the genes have been identified. In this review we will describe the phenotypes associated with these loci and discuss the responsible gene. This article is part of a Special Issue entitled "Advances in dystonia".
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CSN complex controls the stability of selected synaptic proteins via a torsinA-dependent process. EMBO J 2010; 30:181-93. [PMID: 21102408 DOI: 10.1038/emboj.2010.285] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Accepted: 10/20/2010] [Indexed: 11/08/2022] Open
Abstract
DYT1 dystonia is caused by an autosomal dominant mutation that leads to a glutamic acid deletion in torsinA (TA), a member of the AAA+ ATPase superfamily. In this study, we identified a novel-binding partner of TA, the subunit 4 (CSN4) of CSN signalosome. TA binds CSN4 and the synaptic regulator snapin in neuroblastoma cells and in brain synaptosomes. CSN4 and TA are required for the stability of both snapin and the synaptotagmin-specific endocytic adaptor stonin 2, as downregulation of CSN4 or TA reduces the levels of both proteins. Snapin is phosphorylated by the CSN-associated kinase protein kinase D (PKD) and its expression is decreased upon PKD inhibition. In contrast, the stability of stonin 2 is regulated by neddylation, another CSN-associated activity. Overexpression of the pathological TA mutant (ΔE-TA) reduces stonin 2 expression, causing the accumulation of the calcium sensor synaptotagmin 1 on the cell surface. Retrieval of surface-stranded synaptotagmin 1 is restored by overexpression of stonin 2 in ΔE-TA-expressing cells, suggesting that the DYT1 mutation compromises the role of TA in protein stabilisation and synaptic vesicle recycling.
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Characterization of Atp1a3 mutant mice as a model of rapid-onset dystonia with parkinsonism. Behav Brain Res 2010; 216:659-65. [PMID: 20850480 DOI: 10.1016/j.bbr.2010.09.009] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 09/06/2010] [Accepted: 09/08/2010] [Indexed: 11/23/2022]
Abstract
Rapid-onset dystonia with parkinsonism (RDP) or DYT12 dystonia is a rare form of primary, generalized dystonia. Patients do not present with any symptoms until triggered by a physiological stressor. Within days, patients will show both dystonia and parkinsonism. Mutations resulting in a loss of function in the ATP1A3 gene have been identified as the cause of RDP. ATP1A3 encodes the α3 subunit of the Na(+)/K(+)-ATPase, which is exclusively expressed in neurons and cardiac cells. We have previously created a line of mice harboring a point mutation of the Atp1a3 gene (mouse homolog of the human ATP1A3 gene) that results in a loss of function of the α3 subunit. The Atp1a3 mutant mice showed hyperactivity, spatial learning and memory deficits, and increased locomotion induced by methamphetamine. However, the full spectrum of the motor phenotype has not been characterized in the mutant mice and it is not known whether triggers such as restraint stress affect the motor phenotype. Here, we characterized the motor phenotype in normal heterozygous Atp1a3 mutant mice and heterozygous Atp1a3 mutant mice that have been exposed to a restraint stress. We found that this type of trigger induced significant deficits in motor coordination and balance in the mutant mice, characteristic of other genotypic dystonia mouse models. Furthermore, stressed mutant mice also had a decreased thermal sensitivity and alterations in monoamine metabolism. These results suggest that the Atp1a3 mutant mouse models several characteristics of RDP and further analysis of this mouse model will provide great insight into pathogenesis of RDP.
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28
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Abstract
DYT1 dystonia is an autosomal dominant movement disorder, characterized by early onset of involuntary sustained muscle contractions. It is caused by a 3-bp deletion in the DYT1 gene, which results in the deletion of a single glutamate residue in the C-terminus of the protein TA (torsinA). TA is a member of the AAA+ (ATPase associated with various cellular activities) family of chaperones with multiple functions in the cell. There is no evidence of neurodegeneration in DYT1 dystonia, which suggests that mutant TA leads to functional neuronal abnormalities, leading to dystonic movements. In recent years, different functional roles have been attributed to TA, including being a component of the cytoskeleton and the NE (nuclear envelope), and involvement in the secretory pathway and SV (synaptic vesicle) machinery. The aim of the present review is to summarize these findings and the different models proposed, which have contributed to our current understanding of the function of TA, and also to discuss the evidence implicating TA in SV function.
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Page ME, Bao L, Andre P, Pelta-Heller J, Sluzas E, Gonzalez-Alegre P, Bogush A, Khan LE, Iacovitti L, Rice ME, Ehrlich ME. Cell-autonomous alteration of dopaminergic transmission by wild type and mutant (DeltaE) TorsinA in transgenic mice. Neurobiol Dis 2010; 39:318-26. [PMID: 20460154 DOI: 10.1016/j.nbd.2010.04.016] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Revised: 04/15/2010] [Accepted: 04/26/2010] [Indexed: 02/03/2023] Open
Abstract
Early onset torsion dystonia is an autosomal dominant movement disorder of variable penetrance caused by a glutamic acid, i.e. DeltaE, deletion in DYT1, encoding the protein TorsinA. Genetic and structural data implicate basal ganglia dysfunction in dystonia. TorsinA, however, is diffusely expressed, and therefore the primary source of dysfunction may be obscured in pan-neuronal transgenic mouse models. We utilized the tyrosine hydroxylase (TH) promoter to direct transgene expression specifically to dopaminergic neurons of the midbrain to identify cell-autonomous abnormalities. Expression of both the human wild type (hTorsinA) and mutant (DeltaE-hTorsinA) protein resulted in alterations of dopamine release as detected by microdialysis and fast cycle voltammetry. Motor abnormalities detected in these mice mimicked those noted in transgenic mice with pan-neuronal transgene expression. The locomotor response to cocaine in both TH-hTorsinA and TH-DeltaE-hTorsinA, in the face of abnormal extracellular DA levels relative to non-transgenic mice, suggests compensatory, post-synaptic alterations in striatal DA transmission. This is the first cell-subtype-specific DYT1 transgenic mouse that can serve to differentiate between primary and secondary changes in dystonia, thereby helping to target disease therapies.
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Affiliation(s)
- Michelle E Page
- Thomas Jefferson University, Department of Neurosurgery, Farber Institute for Neurosciences, Philadelphia, PA 19107, USA
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Chen XP, Hu XH, Wu SH, Zhang YW, Xiao B, Shang HF. RNA interference-mediated inhibition of wild-type Torsin A expression increases apoptosis caused by oxidative stress in cultured cells. Neurochem Res 2010; 35:1214-23. [PMID: 20455020 DOI: 10.1007/s11064-010-0177-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2010] [Indexed: 02/05/2023]
Abstract
To assess RNAi mediated inhibition of the expression of wt-DYT1 on H(2)O(2)-induced toxicity in NIH 3T3 cells and primary cortical neurons. To detect the function of wild-type Torsin A and the effect of SiRNA on the wt-DYT1 gene. The shRNA expression vector was constructed by ligating annealed complementary shRNA oligonucleotides into the down-stream of the human U6 promoter (PU6) of the RNAi-ready pSIREN-Shuttle vector. Then, the pSIREN-Shuttle-DYT1-shRNA cassette was ligated to Adeno-X Viral DNA to construct the recombinant adenoviral vector pAd-DYT1-shRNA. Cultured cerebral cortical neurons and NIH 3T3 cells were transfected with pAd-DYT1-shRNA and pSIREN-Shuttle-DYT1-shRNA. We evaluated NIH 3T3 cells and neurons in the presence of oxidative stress using a TUNEL assay under different conditions. The knockdown efficacy of the DYT1 was confirmed by real-time RT-PCR and Western Blot analysis. After exposure to H(2)O(2,) the quantity of NIH 3T3 cells transfected with pSIREN-Shuttle-DYT1-shRNA, which stained positively in the TUNEL assay, was significantly higher than the cells transfected with pSIREN-Shuttle-negative control-shRNA. (44.85 +/- 1.81% vs. 8.98 +/- 2.73%, t = 26.168). There were significantly more apoptotic neurons infected with pAd-DYT1-shRNA (45.63 +/- 7.53%) than neurons infected with pAd-X-negative control-shRNA (17.33 +/- 2.43%) (t = 9.816). The observed silencing of wild-type Torsin A expression by DYT1-shRNA was sequence-specific. RNAi-mediated inhibition of the expression of wild-type Torsin A increases apoptosis caused by oxidative stress. It is reasonable to consider that wild-type Torsin A has the capacity to protect cortical neurons against oxidative stress, and in the development of DYT1-delta GAG-dystonia the neuroprotective function of wild-type Torsin A may be compromised.
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Affiliation(s)
- Xue-Ping Chen
- Department of Neurology, West China Hospital, SiChuan University, Chengdu, Sichuan, China
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Morgan GW, Hollinshead M, Ferguson BJ, Murphy BJ, Carpentier DCJ, Smith GL. Vaccinia protein F12 has structural similarity to kinesin light chain and contains a motor binding motif required for virion export. PLoS Pathog 2010; 6:e1000785. [PMID: 20195521 PMCID: PMC2829069 DOI: 10.1371/journal.ppat.1000785] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Accepted: 01/21/2010] [Indexed: 01/16/2023] Open
Abstract
Vaccinia virus (VACV) uses microtubules for export of virions to the cell surface and this process requires the viral protein F12. Here we show that F12 has structural similarity to kinesin light chain (KLC), a subunit of the kinesin-1 motor that binds cargo. F12 and KLC share similar size, pI, hydropathy and cargo-binding tetratricopeptide repeats (TPRs). Moreover, molecular modeling of F12 TPRs upon the crystal structure of KLC2 TPRs showed a striking conservation of structure. We also identified multiple TPRs in VACV proteins E2 and A36. Data presented demonstrate that F12 is critical for recruitment of kinesin-1 to virions and that a conserved tryptophan and aspartic acid (WD) motif, which is conserved in the kinesin-1-binding sequence (KBS) of the neuronal protein calsyntenin/alcadein and several other cellular kinesin-1 binding proteins, is essential for kinesin-1 recruitment and virion transport. In contrast, mutation of WD motifs in protein A36 revealed they were not required for kinesin-1 recruitment or IEV transport. This report of a viral KLC-like protein containing a KBS that is conserved in several cellular proteins advances our understanding of how VACV recruits the kinesin motor to virions, and exemplifies how viruses use molecular mimicry of cellular components to their advantage.
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Affiliation(s)
- Gareth W. Morgan
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Michael Hollinshead
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Brian J. Ferguson
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Brendan J. Murphy
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - David C. J. Carpentier
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Geoffrey L. Smith
- Department of Virology, Faculty of Medicine, Imperial College London, London, United Kingdom
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Walter M, Bonin M, Pullman RS, Valente EM, Loi M, Gambarin M, Raymond D, Tinazzi M, Kamm C, Glöckle N, Poths S, Gasser T, Bressman SB, Klein C, Ozelius LJ, Riess O, Grundmann K. Expression profiling in peripheral blood reveals signature for penetrance in DYT1 dystonia. Neurobiol Dis 2010; 38:192-200. [PMID: 20053375 DOI: 10.1016/j.nbd.2009.12.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 12/14/2009] [Accepted: 12/20/2009] [Indexed: 11/27/2022] Open
Abstract
DYT1 dystonia is an autosomal-dominantly inherited movement disorder, which is usually caused by a GAG deletion in the TOR1A gene. Due to the reduced penetrance of approximately 30-40%, the determination of the mutation in a subject is of limited use with regard to actual manifestation of symptoms. In the present study, we used Affymetrix oligonucleotide microarrays to analyze global gene expression in blood samples of 15 manifesting and 15 non-manifesting mutation carriers in order to identify a susceptibility profile beyond the GAG deletion which is associated with the manifestation of symptoms in DYT1 dystonia. We identified a genetic signature which distinguished between asymptomatic mutation carriers and symptomatic DYT1 patients with 86.7% sensitivity and 100% specificity. This genetic signature could correctly predict the disease state in an independent test set with a sensitivity of 87.5% and a specificity of 85.7%. Conclusively, this genetic signature might provide a possibility to distinguish DYT1 patients from asymptomatic mutation carriers.
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Affiliation(s)
- M Walter
- Department of Medical Genetics, Institute of Human Genetics, University of Tuebingen, Tuebingen, Germany
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Jungwirth M, Dear ML, Brown P, Holbrook K, Goodchild R. Relative tissue expression of homologous torsinB correlates with the neuronal specific importance of DYT1 dystonia-associated torsinA. Hum Mol Genet 2009; 19:888-900. [DOI: 10.1093/hmg/ddp557] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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O'Farrell CA, Martin KL, Hutton M, Delatycki MB, Cookson MR, Lockhart PJ. Mutant torsinA interacts with tyrosine hydroxylase in cultured cells. Neuroscience 2009; 164:1127-37. [PMID: 19761814 DOI: 10.1016/j.neuroscience.2009.09.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Revised: 08/18/2009] [Accepted: 09/09/2009] [Indexed: 01/22/2023]
Abstract
A specific mutation (DeltaE302/303) in the torsinA gene underlies most cases of dominantly inherited early-onset torsion dystonia. This mutation causes the protein to aggregate and form intracellular inclusion bodies in cultured cells and animal models. Co-expression of the wildtype and mutant proteins resulted in the redistribution of the wildtype protein from the endoplasmic reticulum to inclusion bodies in cultured HEK293 cells, and this was associated with increased interaction between the two proteins. Expression of DeltaE302/303 but not wildtype torsinA in primary postnatal midbrain neurons resulted in the formation of intracellular inclusion bodies, predominantly in dopaminergic neurons. Tyrosine hydroxylase was sequestered in these inclusions and this process was mediated by increased protein-protein interaction between mutant torsinA and tyrosine hydroxylase. Analysis in an inducible neuroblastoma cell culture model demonstrated altered tyrosine hydroxylase activity in the presence of the mutant but not wildtype torsinA protein. Our results suggest that the interaction of tyrosine hydroxylase and mutant torsinA may contribute to the phenotype and reported dopaminergic dysfunction in torsinA-mediated dystonia.
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Affiliation(s)
- C A O'Farrell
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA
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Martin JN, Bair TB, Bode N, Dauer WT, Gonzalez-Alegre P. Transcriptional and proteomic profiling in a cellular model of DYT1 dystonia. Neuroscience 2009; 164:563-72. [PMID: 19665049 DOI: 10.1016/j.neuroscience.2009.07.068] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 07/27/2009] [Accepted: 07/28/2009] [Indexed: 10/20/2022]
Abstract
DYT1, the most common inherited dystonia, is caused by a common dominant mutation in the TOR1A gene that leads to a glutamic acid deletion in the protein torsinA. Wild-type torsinA locates preferentially in the endoplasmic reticulum while the disease-linked mutant accumulates in the nuclear envelope. As a result, it has been proposed that DYT1 pathogenesis could result either from transcriptional dysregulation caused by abnormal interactions of mutant torsinA with nuclear envelope proteins, or from a loss of torsinA function in the endoplasmic reticulum that would impair specific neurobiological pathways. Aiming to determine whether one or both of these potential mechanisms are implicated in DYT1 pathogenesis, we completed unbiased transcriptional and proteomic profiling in well-characterized neural cell lines that inducibly express wild-type or mutant torsinA. These experiments demonstrated that the accumulation of mutant torsinA in the nuclear envelope is not sufficient to cause transcriptional dysregulation. However, we detected expression changes at the protein level that, together with other reports, suggest a potential implication of torsinA on energy metabolism and regulation of the redox state. Furthermore, several proteins identified in this study have been previously linked to other forms of dystonia. In conclusion, our results argue against the hypothesis of transcriptional dysregulation in DYT1 dystonia, suggesting potential alternative pathogenic pathways.
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Affiliation(s)
- J N Martin
- Graduate Program in Genetics, The University of Iowa, Iowa City, IA, USA
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Argyelan M, Carbon M, Niethammer M, Uluğ AM, Voss HU, Bressman SB, Dhawan V, Eidelberg D. Cerebellothalamocortical connectivity regulates penetrance in dystonia. J Neurosci 2009; 29:9740-7. [PMID: 19657027 PMCID: PMC2745646 DOI: 10.1523/jneurosci.2300-09.2009] [Citation(s) in RCA: 229] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 06/16/2009] [Accepted: 06/20/2009] [Indexed: 11/21/2022] Open
Abstract
Dystonia is a brain disorder characterized by sustained involuntary muscle contractions. It is typically inherited as an autosomal dominant trait with incomplete penetrance. While lacking clear degenerative neuropathology, primary dystonia is thought to involve microstructural and functional changes in neuronal circuitry. In the current study, we used magnetic resonance diffusion tensor imaging and probabilistic tractography to identify the specific circuit abnormalities that underlie clinical penetrance in carriers of genetic mutations for this disorder. This approach revealed reduced integrity of cerebellothalamocortical fiber tracts, likely developmental in origin, in both manifesting and clinically nonmanifesting dystonia mutation carriers. In these subjects, reductions in cerebellothalamic connectivity correlated with increased motor activation responses, consistent with loss of inhibition at the cortical level. Nonmanifesting mutation carriers were distinguished by an additional area of fiber tract disruption situated distally along the thalamocortical segment of the pathway, in tandem with the proximal cerebellar outflow abnormality. In individual gene carriers, clinical penetrance was determined by the difference in connectivity measured at these two sites. Overall, these findings point to a novel mechanism to explain differences in clinical expression in carriers of genes for brain disease.
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Affiliation(s)
- Miklos Argyelan
- Center for Neurosciences, The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, New York 11030
| | - Maren Carbon
- Center for Neurosciences, The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, New York 11030
- Departments of Neurology and
- Medicine, North Shore University Hospital and New York University School of Medicine, Manhasset, New York 11030
| | - Martin Niethammer
- Center for Neurosciences, The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, New York 11030
- Departments of Neurology and
- Medicine, North Shore University Hospital and New York University School of Medicine, Manhasset, New York 11030
| | - Aziz M. Uluğ
- Center for Neurosciences, The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, New York 11030
| | - Henning U. Voss
- Department of Radiology, Weill Cornell Medical College, New York, New York 10065, and
| | - Susan B. Bressman
- Mirken Department of Neurology, Beth Israel Medical Center, New York, New York 10003
| | - Vijay Dhawan
- Center for Neurosciences, The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, New York 11030
- Departments of Neurology and
- Medicine, North Shore University Hospital and New York University School of Medicine, Manhasset, New York 11030
| | - David Eidelberg
- Center for Neurosciences, The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, New York 11030
- Departments of Neurology and
- Medicine, North Shore University Hospital and New York University School of Medicine, Manhasset, New York 11030
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Giles LM, Li L, Chin LS. Printor, a novel torsinA-interacting protein implicated in dystonia pathogenesis. J Biol Chem 2009; 284:21765-75. [PMID: 19535332 DOI: 10.1074/jbc.m109.004838] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Early onset generalized dystonia (DYT1) is an autosomal dominant neurological disorder caused by deletion of a single glutamate residue (torsinA DeltaE) in the C-terminal region of the AAA(+) (ATPases associated with a variety of cellular activities) protein torsinA. The pathogenic mechanism by which torsinA DeltaE mutation leads to dystonia remains unknown. Here we report the identification and characterization of a 628-amino acid novel protein, printor, that interacts with torsinA. Printor co-distributes with torsinA in multiple brain regions and co-localizes with torsinA in the endoplasmic reticulum. Interestingly, printor selectively binds to the ATP-free form but not to the ATP-bound form of torsinA, supporting a role for printor as a cofactor rather than a substrate of torsinA. The interaction of printor with torsinA is completely abolished by the dystonia-associated torsinA DeltaE mutation. Our findings suggest that printor is a new component of the DYT1 pathogenic pathway and provide a potential molecular target for therapeutic intervention in dystonia.
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Affiliation(s)
- Lisa M Giles
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Abstract
A GAG deletion in the DYT1 gene is responsible for the autosomal dominant movement disorder, early onset primary torsion dystonia, which is characterised by involuntary sustained muscle contractions and abnormal posturing of the limbs. The mutation leads to deletion of a single glutamate residue in the C-terminus of the protein torsinA, a member of the AAA+ ATPase family of proteins with multiple functions. Since no evidence of neurodegeneration has been found in DYT1 patients, the dystonic phenotype is likely to be the result of neuronal functional defect(s), the nature of which is only partially understood. Biochemical, structural and cell biological studies have been performed in order to characterise torsinA. These studies, together with the generation of several animal models, have contributed to identify cellular compartments and pathways, including the cytoskeleton and the nuclear envelope, the secretory pathway and the synaptic vesicle machinery where torsinA function may be crucial. However, the role of torsinA and the correlation between the dysfunction caused by the mutation and the dystonic phenotype remain unclear. This review provides an overview of the findings of the last ten years of research on torsinA, a critical evaluation of the different models proposed and insights towards future avenues of research.
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Affiliation(s)
- Alessandra Granata
- Department of Clinical Neurosciences, UCL Institute of Neurology, London, UK.
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Characterization of the porcine TOR1A gene: The first step towards generation of a pig model for dystonia. Gene 2009; 430:105-15. [DOI: 10.1016/j.gene.2008.10.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 10/14/2008] [Accepted: 10/14/2008] [Indexed: 01/11/2023]
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Shimamoto S, Takata M, Tokuda M, Oohira F, Tokumitsu H, Kobayashi R. Interactions of S100A2 and S100A6 with the tetratricopeptide repeat proteins, Hsp90/Hsp70-organizing protein and kinesin light chain. J Biol Chem 2008; 283:28246-58. [PMID: 18669640 PMCID: PMC2661394 DOI: 10.1074/jbc.m801473200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 07/09/2008] [Indexed: 11/06/2022] Open
Abstract
S100A2 and S100A6 interact with several target proteins in a Ca2+-regulated manner. However, the exact intracellular roles of the S100 proteins are unclear. In this study we identified Hsp70/Hsp90-organizing protein (Hop) and kinesin light chain (KLC) as novel targets of S100A2 and S100A6. Hop directly associates with Hsp70 and Hsp90 through the tetratricopeptide (TPR) domains and regulates Hop-Hsp70 and Hop-Hsp90 complex formation. We have found that S100A2 and S100A6 bind to the TPR domain of Hop, resulting in inhibition of the Hop-Hsp70 and Hop-Hsp90 interactions in vitro. Although endogenous Hsp70 and Hsp90 interact with Hop in resting Cos-7 cells, but not with S100A6, stimulation of these cells with ionomycin caused a Hop-S100A6 interaction, resulting in the dissociation of Hsp70 and Hsp90 from Hop. Similarly, glutathione S-transferase pulldown and co-immunoprecipitation experiments revealed that S100A6 binds to the TPR domain of KLC, resulting in inhibition of the KLC-c-Jun N-terminal kinase (JNK)-interacting protein 1 (JIP-1) interaction in vitro. The transiently expressed JIP-1 interacts with KLC in resting Cos-7 cells but not with S100A6. Stimulation of these cells with ionomycin also caused a KLC-S100A6 interaction, resulting in dissociation of JIP-1 from KLC. These results strongly suggest that the S100 proteins modulate Hsp70-Hop-Hsp90 multichaperone complex formation and KLC-cargo interaction via Ca2+-dependent S100 protein-TPR protein complex formation in vivo as well as in vitro. Moreover, we have shown that S100A2 and S100A6 interact with another TPR protein Tom70 and regulate the Tom70-ligand interaction in vitro. Thus, our findings suggest a new intracellular Ca2+-signaling pathway via S100 proteins-TPR motif interactions.
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Affiliation(s)
- Seiko Shimamoto
- Department of Signal Transduction Sciences, Kagawa University Faculty of Medicine, 1750-1 Ikenobe, Kita-gun, Kagawa 761-0793, Japan
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Nery FC, Zeng J, Niland BP, Hewett J, Farley J, Irimia D, Li Y, Wiche G, Sonnenberg A, Breakefield XO. TorsinA binds the KASH domain of nesprins and participates in linkage between nuclear envelope and cytoskeleton. J Cell Sci 2008; 121:3476-86. [PMID: 18827015 DOI: 10.1242/jcs.029454] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A specific mutation (DeltaE) in torsinA underlies most cases of the dominantly inherited movement disorder, early-onset torsion dystonia (DYT1). TorsinA, a member of the AAA+ ATPase superfamily, is located within the lumen of the nuclear envelope (NE) and endoplasmic reticulum (ER). We investigated an association between torsinA and nesprin-3, which spans the outer nuclear membrane (ONM) of the NE and links it to vimentin via plectin in fibroblasts. Mouse nesprin-3alpha co-immunoprecipitated with torsinA and this involved the C-terminal region of torsinA and the KASH domain of nesprin-3alpha. This association with human nesprin-3 appeared to be stronger for torsinADeltaE than for torsinA. TorsinA also associated with the KASH domains of nesprin-1 and -2 (SYNE1 and 2), which link to actin. In the absence of torsinA, in knockout mouse embryonic fibroblasts (MEFs), nesprin-3alpha was localized predominantly in the ER. Enrichment of yellow fluorescent protein (YFP)-nesprin-3 in the ER was also seen in the fibroblasts of DYT1 patients, with formation of YFP-positive globular structures enriched in torsinA, vimentin and actin. TorsinA-null MEFs had normal NE structure, but nuclear polarization and cell migration were delayed in a wound-healing assay, as compared with wild-type MEFs. These studies support a role for torsinA in dynamic interactions between the KASH domains of nesprins and their protein partners in the lumen of the NE, with torsinA influencing the localization of nesprins and associated cytoskeletal elements and affecting their role in nuclear and cell movement.
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Affiliation(s)
- Flávia C Nery
- Molecular Neurogenetics Unit, Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Program in Neuroscience, Harvard Medical School, Boston, MA 02114, USA
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Hirokawa N, Noda Y. Intracellular Transport and Kinesin Superfamily Proteins, KIFs: Structure, Function, and Dynamics. Physiol Rev 2008; 88:1089-118. [DOI: 10.1152/physrev.00023.2007] [Citation(s) in RCA: 345] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Various molecular cell biology and molecular genetic approaches have indicated significant roles for kinesin superfamily proteins (KIFs) in intracellular transport and have shown that they are critical for cellular morphogenesis, functioning, and survival. KIFs not only transport various membrane organelles, protein complexes, and mRNAs for the maintenance of basic cellular activity, but also play significant roles for various mechanisms fundamental for life, such as brain wiring, higher brain functions such as memory and learning and activity-dependent neuronal survival during brain development, and for the determination of important developmental processes such as left-right asymmetry formation and suppression of tumorigenesis. Accumulating data have revealed a molecular mechanism of cargo recognition involving scaffolding or adaptor protein complexes. Intramolecular folding and phosphorylation also regulate the binding activity of motor proteins. New techniques using molecular biophysics, cryoelectron microscopy, and X-ray crystallography have detected structural changes in motor proteins, synchronized with ATP hydrolysis cycles, leading to the development of independent models of monomer and dimer motors for processive movement along microtubules.
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Zhao Y, Xiao J, Ueda M, Wang Y, Hines M, Nowak TS, LeDoux MS. Glial elements contribute to stress-induced torsinA expression in the CNS and peripheral nervous system. Neuroscience 2008; 155:439-53. [PMID: 18538941 DOI: 10.1016/j.neuroscience.2008.04.053] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 04/22/2008] [Accepted: 04/25/2008] [Indexed: 12/31/2022]
Abstract
DYT1 dystonia is caused by a single GAG deletion in exon 5 of TOR1A, the gene encoding torsinA, a putative chaperone protein. In this study, central and peripheral nervous system perturbations (transient forebrain ischemia and sciatic nerve transection, respectively) were used to examine the systems biology of torsinA in rats. After forebrain ischemia, quantitative real-time reverse transcriptase-polymerase chain reaction identified increased torsinA transcript levels in hippocampus, cerebral cortex, thalamus, striatum, and cerebellum at 24 h and 7 days. Expression declined toward sham values by 14 days in striatum, thalamus and cortex, and by 21 days in cerebellum and hippocampus. TorsinA transcripts were localized to dentate granule cells and pyramidal neurons in control hippocampus and were moderately elevated in these cell populations at 24 h after ischemia, after which CA1 expression was reduced, consistent with the loss of this vulnerable neuronal population. Increased in situ hybridization signal in CA1 stratum radiatum, stratum lacunosum-moleculare, and stratum oriens at 7 days after ischemia was correlated with the detection of torsinA immunoreactivity in interneurons and reactive astrocytes at 7 and 14 days. Sciatic nerve transection increased torsinA transcript levels between 24 h and 7 days in both ipsilateral and contralateral dorsal root ganglia (DRG). However, increased torsinA immunoreactivity was localized to both ganglion cells and satellite cells in ipsilateral DRG but was restricted to satellite cells contralaterally. These results suggest that torsinA participates in the response of neural tissue to central and peripheral insults and its sustained up-regulation indicates that torsinA may contribute to remodeling of neuronal circuitry. The striking induction of torsinA in astrocytes and satellite cells points to the potential involvement of glial elements in the pathobiology of DYT1 dystonia.
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Affiliation(s)
- Y Zhao
- University of Tennessee Health Science Center, Departments of Neurology and Anatomy and Neurobiology, 855 Monroe Avenue, Suite 415, Memphis, TN 38163, USA
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Hammond JW, Griffin K, Jih GT, Stuckey J, Verhey KJ. Co-operative Versus Independent Transport of Different Cargoes by Kinesin-1. Traffic 2008; 9:725-41. [DOI: 10.1111/j.1600-0854.2008.00722.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Abstract
Early-onset torsion dystonia is a severe generalized form of primary dystonia, with most cases caused by a specific mutation (ΔGAG) in the DYT1 gene encoding torsinA. This mutation is autosomal dominant and is thought to result in reduced torsinA activity. TorsinA is an AAA protein located in the lumen of the endoplasmic reticulum and nuclear envelope of most cells (with high levels in some brain neurons). It is thought to serve as a chaperone protein and/or a link between these membranes and the cytoskeleton. Other sequence variations in DYT1 can affect penetrance of the ΔGAG mutation and may be associated with more common, late-onset focal forms of dystonia. Animal models of DYT1 dystonia are emerging that will allow preclinical evaluation of drugs that can be used to prevent or treat this non-neurodegenerative neurologic disease.
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Affiliation(s)
- Christoph Kamm
- Department of Neurodegenerative Diseases & Hertie-Institute for Clinical Brain Research, University of Tuebingen, Otfried-Mueller-Str. 27 72076 Tuebingen, Germany
| | - Laurie J Ozelius
- Associate Professor Bachmann Strauss Professor, Mount Sinai Medical School, One Gustave L Levy Place, NY 10029, USA
| | - Xandra O Breakefield
- Massachusetts General Hospital-East, Molecular Neurogenetics Unit, 13th Street, Building 149, Charlestown, MA 02129 USA
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Granata A, Watson R, Collinson LM, Schiavo G, Warner TT. The dystonia-associated protein torsinA modulates synaptic vesicle recycling. J Biol Chem 2007; 283:7568-79. [PMID: 18167355 DOI: 10.1074/jbc.m704097200] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The loss of a glutamic acid residue in the AAA-ATPase (ATPases associated with diverse cellular activities) torsinA is responsible for most cases of early onset autosomal dominant primary dystonia. In this study, we found that snapin, which binds SNAP-25 (synaptosome-associated protein of 25,000 Da) and enhances the association of the SNARE complex with synaptotagmin, is an interacting partner for both wild type and mutant torsinA. Snapin co-localized with endogenous torsinA on dense core granules in PC12 cells and was recruited to perinuclear inclusions containing mutant DeltaE-torsinA in neuroblastoma SH-SY5Y cells. In view of these observations, synaptic vesicle recycling was analyzed using the lipophilic dye FM1-43 and an antibody directed against an intravesicular epitope of synaptotagmin I. We found that overexpression of wild type torsinA negatively affects synaptic vesicle endocytosis. Conversely, overexpression of DeltaE-torsinA in neuroblastoma cells increases FM1-43 uptake. Knockdown of snapin and/or torsinA using small interfering RNAs had a similar inhibitory effect on the exo-endocytic process. In addition, down-regulation of torsinA causes the persistence of synaptotagmin I on the plasma membrane, which closely resembles the effect observed by the overexpression of the DeltaE-torsinA mutant. Altogether, these findings suggest that torsinA plays a role together with snapin in regulated exocytosis and that DeltaE-torsinA exerts its pathological effects through a loss of function mechanism. This may affect neuronal uptake of neurotransmitters, such as dopamine, playing a role in the development of dystonic movements.
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Affiliation(s)
- Alessandra Granata
- Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom
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Callan A, Bunning S, Jones O, High S, Swanton E. Biosynthesis of the dystonia-associated AAA+ ATPase torsinA at the endoplasmic reticulum. Biochem J 2007; 401:607-12. [PMID: 17037984 PMCID: PMC1820811 DOI: 10.1042/bj20061313] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
TorsinA is a widely expressed AAA(+) (ATPases associated with various cellular activities) ATPase of unknown function. Previous studies have described torsinA as a type II protein with a cleavable signal sequence, a single membrane spanning domain, and its C-terminus located in the ER (endoplasmic reticulum) lumen. However, in the present study we show that torsinA is not in fact an integral membrane protein. Instead we find that the mature protein associates peripherally with the ER membrane, most likely through an interaction with an integral membrane protein. Consistent with this model, we provide evidence that the signal peptidase complex cleaves the signal sequence of torsinA, and we show that the region previously suggested to form a transmembrane domain is translocated into the lumen of the ER. The finding that torsinA is a peripheral, and not an integral membrane protein as previously thought, has important implications for understanding the function of this novel ATPase.
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Affiliation(s)
- Anna C. Callan
- Faculty of Life Sciences, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, U.K
| | - Sandra Bunning
- Faculty of Life Sciences, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, U.K
| | - Owen T. Jones
- Faculty of Life Sciences, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, U.K
| | - Stephen High
- Faculty of Life Sciences, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, U.K
| | - Eileithyia Swanton
- Faculty of Life Sciences, University of Manchester, The Michael Smith Building, Oxford Road, Manchester M13 9PT, U.K
- To whom correspondence should be addressed (email )
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Esapa CT, Waite A, Locke M, Benson MA, Kraus M, McIlhinney RAJ, Sillitoe RV, Beesley PW, Blake DJ. SGCE missense mutations that cause myoclonus-dystonia syndrome impair ε-sarcoglycan trafficking to the plasma membrane: modulation by ubiquitination and torsinA. Hum Mol Genet 2007; 16:327-42. [PMID: 17200151 DOI: 10.1093/hmg/ddl472] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Myoclonus-dystonia syndrome (MDS) is a genetically heterogeneous disorder characterized by myoclonic jerks often seen in combination with dystonia and psychiatric co-morbidities and epilepsy. Mutations in the gene encoding epsilon-sarcoglycan (SGCE) have been found in some patients with MDS. SGCE is a maternally imprinted gene with the disease being inherited in an autosomal dominant pattern with reduced penetrance upon maternal transmission. In the central nervous system, epsilon-sarcoglycan is widely expressed in neurons of the cerebral cortex, basal ganglia, hippocampus, cerebellum and the olfactory bulb. epsilon-Sarcoglycan is located at the plasma membrane in neurons, muscle and transfected cells. To determine the effect of MDS-associated mutations on the function of epsilon-sarcoglycan we examined the biosynthesis and trafficking of wild-type and mutant proteins in cultured cells. In contrast to the wild-type protein, disease-associated epsilon-sarcoglycan missense mutations (H36P, H36R and L172R) produce proteins that are undetectable at the cell surface and are retained intracellularly. These mutant proteins become polyubiquitinated and are rapidly degraded by the proteasome. Furthermore, torsinA, that is mutated in DYT1 dystonia, a rare type of primary dystonia, binds to and promotes the degradation of epsilon-sarcoglycan mutants when both proteins are co-expressed. These data demonstrate that some MDS-associated mutations in SGCE impair trafficking of the mutant protein to the plasma membrane and suggest a role for torsinA and the ubiquitin proteasome system in the recognition and processing of misfolded epsilon-sarcoglycan.
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Affiliation(s)
- Christopher T Esapa
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
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