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Mulligan RJ, Winckler B. Regulation of Endosomal Trafficking by Rab7 and Its Effectors in Neurons: Clues from Charcot-Marie-Tooth 2B Disease. Biomolecules 2023; 13:1399. [PMID: 37759799 PMCID: PMC10527268 DOI: 10.3390/biom13091399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 09/09/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
Intracellular endosomal trafficking controls the balance between protein degradation and synthesis, i.e., proteostasis, but also many of the cellular signaling pathways that emanate from activated growth factor receptors after endocytosis. Endosomal trafficking, sorting, and motility are coordinated by the activity of small GTPases, including Rab proteins, whose function as molecular switches direct activity at endosomal membranes through effector proteins. Rab7 is particularly important in the coordination of the degradative functions of the pathway. Rab7 effectors control endosomal maturation and the properties of late endosomal and lysosomal compartments, such as coordination of recycling, motility, and fusion with downstream compartments. The spatiotemporal regulation of endosomal receptor trafficking is particularly challenging in neurons because of their enormous size, their distinct intracellular domains with unique requirements (dendrites vs. axons), and their long lifespans as postmitotic, differentiated cells. In Charcot-Marie-Tooth 2B disease (CMT2B), familial missense mutations in Rab7 cause alterations in GTPase cycling and trafficking, leading to an ulcero-mutilating peripheral neuropathy. The prevailing hypothesis to account for CMT2B pathologies is that CMT2B-associated Rab7 alleles alter endocytic trafficking of the neurotrophin NGF and its receptor TrkA and, thereby, disrupt normal trophic signaling in the peripheral nervous system, but other Rab7-dependent pathways are also impacted. Here, using TrkA as a prototypical endocytic cargo, we review physiologic Rab7 effector interactions and control in neurons. Since neurons are among the largest cells in the body, we place particular emphasis on the temporal and spatial regulation of endosomal sorting and trafficking in neuronal processes. We further discuss the current findings in CMT2B mutant Rab7 models, the impact of mutations on effector interactions or balance, and how this dysregulation may confer disease.
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Affiliation(s)
- Ryan J. Mulligan
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22903, USA
- Medical Scientist Training Program, University of Virginia, Charlottesville, VA 22903, USA
| | - Bettina Winckler
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22903, USA
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2
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Rühmkorf A, Harbauer AB. Role of Mitochondria-ER Contact Sites in Mitophagy. Biomolecules 2023; 13:1198. [PMID: 37627263 PMCID: PMC10452924 DOI: 10.3390/biom13081198] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/28/2023] [Accepted: 07/29/2023] [Indexed: 08/27/2023] Open
Abstract
Mitochondria are often referred to as the "powerhouse" of the cell. However, this organelle has many more functions than simply satisfying the cells' metabolic needs. Mitochondria are involved in calcium homeostasis and lipid metabolism, and they also regulate apoptotic processes. Many of these functions require contact with the ER, which is mediated by several tether proteins located on the respective organellar surfaces, enabling the formation of mitochondria-ER contact sites (MERCS). Upon damage, mitochondria produce reactive oxygen species (ROS) that can harm the surrounding cell. To circumvent toxicity and to maintain a functional pool of healthy organelles, damaged and excess mitochondria can be targeted for degradation via mitophagy, a form of selective autophagy. Defects in mitochondria-ER tethers and the accumulation of damaged mitochondria are found in several neurodegenerative diseases, including Parkinson's disease and amyotrophic lateral sclerosis, which argues that the interplay between the two organelles is vital for neuronal health. This review provides an overview of the different mechanisms of mitochondrial quality control that are implicated with the different mitochondria-ER tether proteins, and also provides a novel perspective on how MERCS are involved in mediating mitophagy upon mitochondrial damage.
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Affiliation(s)
- Alina Rühmkorf
- TUM Medical Graduate Center, Technical University of Munich, 81675 Munich, Germany
- Max Planck Institute for Biological Intelligence, 82152 Planegg-Martinsried, Germany
| | - Angelika Bettina Harbauer
- Max Planck Institute for Biological Intelligence, 82152 Planegg-Martinsried, Germany
- Institute of Neuronal Cell Biology, Technical University of Munich, 80802 Munich, Germany
- Munich Cluster for Systems Neurology, 81377 Munich, Germany
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3
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Gonzalez B, Tare A, Ryu S, Johnson SC, Atzmon G, Barzilai N, Kaeberlein M, Suh Y. High-throughput sequencing analysis of nuclear-encoded mitochondrial genes reveals a genetic signature of human longevity. GeroScience 2023; 45:311-330. [PMID: 35948858 PMCID: PMC9886794 DOI: 10.1007/s11357-022-00634-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 07/28/2022] [Indexed: 02/03/2023] Open
Abstract
Mitochondrial dysfunction is a well-known contributor to aging and age-related diseases. The precise mechanisms through which mitochondria impact human lifespan, however, remain unclear. We hypothesize that humans with exceptional longevity harbor rare variants in nuclear-encoded mitochondrial genes (mitonuclear genes) that confer resistance against age-related mitochondrial dysfunction. Here we report an integrated functional genomics study to identify rare functional variants in ~ 660 mitonuclear candidate genes discovered by target capture sequencing analysis of 496 centenarians and 572 controls of Ashkenazi Jewish descent. We identify and prioritize longevity-associated variants, genes, and mitochondrial pathways that are enriched with rare variants. We provide functional gene variants such as those in MTOR (Y2396Lfs*29), CPS1 (T1406N), and MFN2 (G548*) as well as LRPPRC (S1378G) that is predicted to affect mitochondrial translation. Taken together, our results suggest a functional role for specific mitonuclear genes and pathways in human longevity.
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Affiliation(s)
- Brenda Gonzalez
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Archana Tare
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Seungjin Ryu
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Department of Pharmacology, College of Medicine, Hallym University, Chuncheon, Gangwon, 24252, Republic of Korea
| | - Simon C Johnson
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Gil Atzmon
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Department of Biology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Nir Barzilai
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, WA, 98195, USA
| | - Yousin Suh
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
- Departments of Obstetrics and Gynecology, and Genetics and Development, Columbia University, 630 West 168th Street, New York, NY, 10032, USA.
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Abe M, Makino A, Murate M, Hullin-Matsuda F, Yanagawa M, Sako Y, Kobayashi T. PMP2/FABP8 induces PI(4,5)P 2-dependent transbilayer reorganization of sphingomyelin in the plasma membrane. Cell Rep 2021; 37:109935. [PMID: 34758297 DOI: 10.1016/j.celrep.2021.109935] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 08/20/2021] [Accepted: 10/13/2021] [Indexed: 12/11/2022] Open
Abstract
Sphingomyelin (SM) is a mammalian lipid mainly distributed in the outer leaflet of the plasma membrane (PM). We show that peripheral myelin protein 2 (PMP2), a member of the fatty-acid-binding protein (FABP) family, can localize at the PM and controls the transbilayer distribution of SM. Genetic screening with genome-wide small hairpin RNA libraries identifies PMP2 as a protein involved in the transbilayer movement of SM. A biochemical assay demonstrates that PMP2 is a phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2)-binding protein. PMP2 induces the tubulation of model membranes in a PI(4,5)P2-dependent manner, accompanied by the modification of the transbilayer membrane distribution of lipids. In the PM of PMP2-overexpressing cells, inner-leaflet SM is increased whereas outer-leaflet SM is reduced. PMP2 is a causative protein of Charcot-Marie-Tooth disease (CMT). A mutation in PMP2 associated with CMT increases its affinity for PI(4,5)P2, inducing membrane tubulation and the subsequent transbilayer movement of lipids.
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Affiliation(s)
- Mitsuhiro Abe
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan.
| | - Asami Makino
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Motohide Murate
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch, France
| | - Françoise Hullin-Matsuda
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Université de Lyon, CarMeN Laboratory, INSERM U1060, INRAE U1397, Université Claude Bernard Lyon 1, 69495 Pierre-Benite, France
| | - Masataka Yanagawa
- Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Cellular Informatics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan; Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 67401 Illkirch, France.
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Hong JM, Jeon H, Choi YC, Cho H, Hong YB, Park HJ. A Compound Heterozygous Pathogenic Variant in B4GALNT1 Is Associated With Axonal Charcot-Marie-Tooth Disease. J Clin Neurol 2021; 17:534-540. [PMID: 34595861 PMCID: PMC8490901 DOI: 10.3988/jcn.2021.17.4.534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/08/2021] [Accepted: 06/08/2021] [Indexed: 11/17/2022] Open
Abstract
Background and Purpose Pathogenic variants in B4GALNT1 have been reported to cause hereditary spastic paraplegia 26. This study has revealed that a novel compound heterozygous pathogenic variant in B4GALNT1 is associated with axonal Charcot-Marie-Tooth disease (CMT). Methods Whole-exome sequencing (WES) was used to identify the causative factors and characterize the clinical features of a Korean family with sensorimotor polyneuropathy. Functional assessment of the mutant genes was performed using a motor neuron cell line. Results The WES revealed a compound heterozygous pathogenic variant (c.128dupC and c.451G>A) in B4GALNT1 as the causative of the present patient, a 53-year-old male who presented with axonal sensorimotor polyneuropathy and cognitive impairment without spasticity. The electrodiagnostic study showed axonal sensorimotor polyneuropathy. B4GALNT1 was critical to the proliferation of motor neuron cells. The compensation assay revealed that the pathogenic variants might affect the enzymatic activity of B4GALNT1. Conclusions This study is the first to identify a case of autosomal recessive axonal CMT associated with a compound heterozygous pathogenic variant in B4GALNT1. This finding expands the clinical and genetic spectra of peripheral neuropathy.
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Affiliation(s)
- Ji Man Hong
- Department of Neurology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Korea
| | - Hyeonjin Jeon
- Department of Biochemistry, College of Medicine, Dong-A University, Busan, Korea.,Department of Translational Biomedical Sciences, Graduate School of Dong-A University, Busan, Korea
| | - Young Chul Choi
- Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Hanna Cho
- Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Young Bin Hong
- Department of Biochemistry, College of Medicine, Dong-A University, Busan, Korea.,Department of Translational Biomedical Sciences, Graduate School of Dong-A University, Busan, Korea.
| | - Hyung Jun Park
- Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
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Shen S, Picci C, Ustinova K, Benoy V, Kutil Z, Zhang G, Tavares MT, Pavlíček J, Zimprich CA, Robers MB, Van Den Bosch L, Bařinka C, Langley B, Kozikowski AP. Tetrahydroquinoline-Capped Histone Deacetylase 6 Inhibitor SW-101 Ameliorates Pathological Phenotypes in a Charcot-Marie-Tooth Type 2A Mouse Model. J Med Chem 2021; 64:4810-4840. [PMID: 33830764 DOI: 10.1021/acs.jmedchem.0c02210] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Histone deacetylase 6 (HDAC6) is a promising therapeutic target for the treatment of neurodegenerative disorders. SW-100 (1a), a phenylhydroxamate-based HDAC6 inhibitor (HDAC6i) bearing a tetrahydroquinoline (THQ) capping group, is a highly potent and selective HDAC6i that was shown to be effective in mouse models of Fragile X syndrome and Charcot-Marie-Tooth disease type 2A (CMT2A). In this study, we report the discovery of a new THQ-capped HDAC6i, termed SW-101 (1s), that possesses excellent HDAC6 potency and selectivity, together with markedly improved metabolic stability and druglike properties compared to SW-100 (1a). X-ray crystallography data reveal the molecular basis of HDAC6 inhibition by SW-101 (1s). Importantly, we demonstrate that SW-101 (1s) treatment elevates the impaired level of acetylated α-tubulin in the distal sciatic nerve, counteracts progressive motor dysfunction, and ameliorates neuropathic symptoms in a CMT2A mouse model bearing mutant MFN2. Taken together, these results bode well for the further development of SW-101 (1s) as a disease-modifying HDAC6i.
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Affiliation(s)
- Sida Shen
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
| | - Cristina Picci
- School of Health, The University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand
| | - Kseniya Ustinova
- Institute of Biotechnology of the Czech Academy of Sciences, 252 50 Vestec, Czech Republic
| | - Veronick Benoy
- Laboratory of Neurobiology, Center for Brain & Disease (VIB) and Leuven Brain Institute (LBI), KU Leuven, B-3000 Leuven, Belgium
| | - Zsófia Kutil
- Institute of Biotechnology of the Czech Academy of Sciences, 252 50 Vestec, Czech Republic
| | - Guiping Zhang
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
| | - Maurício T Tavares
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
| | - Jiří Pavlíček
- Institute of Biotechnology of the Czech Academy of Sciences, 252 50 Vestec, Czech Republic
| | - Chad A Zimprich
- Promega Corporation, Madison, Wisconsin 53711, United States
| | | | - Ludo Van Den Bosch
- Laboratory of Neurobiology, Center for Brain & Disease (VIB) and Leuven Brain Institute (LBI), KU Leuven, B-3000 Leuven, Belgium
| | - Cyril Bařinka
- Institute of Biotechnology of the Czech Academy of Sciences, 252 50 Vestec, Czech Republic
| | - Brett Langley
- School of Health, The University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand
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Navaratnarajah T, Anand R, Reichert AS, Distelmaier F. The relevance of mitochondrial morphology for human disease. Int J Biochem Cell Biol 2021; 134:105951. [PMID: 33610749 DOI: 10.1016/j.biocel.2021.105951] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 02/01/2021] [Accepted: 02/03/2021] [Indexed: 12/18/2022]
Abstract
Mitochondria are highly dynamic organelles, which undergo frequent structural and metabolic changes to fulfil cellular demands. To facilitate these processes several proteins are required to regulate mitochondrial shape and interorganellar communication. These proteins include the classical mitochondrial fusion (MFN1, MFN2, and OPA1) and fission proteins (DRP1, MFF, FIS1, etc.) as well as several other proteins that are directly or indirectly involved in these processes (e.g. YME1L, OMA1, INF2, GDAP1, MIC13, etc.). During the last two decades, inherited genetic defects in mitochondrial fusion and fission proteins have emerged as an important class of neurodegenerative human diseases with variable onset ranging from infancy to adulthood. So far, no causal treatment strategies are available for these disorders. In this review, we provide an overview about the current knowledge on mitochondrial dynamics under physiological conditions. Moreover, we describe human diseases, which are associated with genetic defects in these pathways.
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Affiliation(s)
- Tharsini Navaratnarajah
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Ruchika Anand
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich-Heine-University-Düsseldorf, Düsseldorf, Germany
| | - Andreas S Reichert
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich-Heine-University-Düsseldorf, Düsseldorf, Germany
| | - Felix Distelmaier
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
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8
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Genetic mechanisms of peripheral nerve disease. Neurosci Lett 2020; 742:135357. [PMID: 33249104 DOI: 10.1016/j.neulet.2020.135357] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/24/2020] [Accepted: 09/02/2020] [Indexed: 12/17/2022]
Abstract
Peripheral neuropathies of genetic etiology are a very diverse group of disorders manifesting either as non-syndromic inherited neuropathies without significant manifestations outside the peripheral nervous system, or as part of a systemic or syndromic genetic disorder. The former and most frequent group is collectively known as Charcot-Marie-Tooth disease (CMT), with prevalence as high as 1:2,500 world-wide, and has proven to be genetically highly heterogeneous. More than 100 different genes have been identified so far to cause various CMT forms, following all possible inheritance patterns. CMT causative genes belong to several common functional pathways that are essential for the integrity of the peripheral nerve. Their discovery has provided insights into the normal biology of axons and myelinating cells, and has highlighted the molecular mechanisms including both loss of function and gain of function effects, leading to peripheral nerve degeneration. Demyelinating neuropathies result from dysfunction of genes primarily affecting myelinating Schwann cells, while axonal neuropathies are caused by genes affecting mostly neurons and their long axons. Furthermore, mutation in genes expressed outside the nervous system, as in the case of inherited amyloid neuropathies, may cause peripheral neuropathy resulting from accumulation of β-structured amyloid fibrils in peripheral nerves in addition to various organs. Increasing insights into the molecular-genetic mechanisms have revealed potential therapeutic targets. These will enable the development of novel therapeutics for genetic neuropathies that remain, in their majority, without effective treatment.
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Guillaud L, El-Agamy SE, Otsuki M, Terenzio M. Anterograde Axonal Transport in Neuronal Homeostasis and Disease. Front Mol Neurosci 2020; 13:556175. [PMID: 33071754 PMCID: PMC7531239 DOI: 10.3389/fnmol.2020.556175] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 08/26/2020] [Indexed: 12/12/2022] Open
Abstract
Neurons are highly polarized cells with an elongated axon that extends far away from the cell body. To maintain their homeostasis, neurons rely extensively on axonal transport of membranous organelles and other molecular complexes. Axonal transport allows for spatio-temporal activation and modulation of numerous molecular cascades, thus playing a central role in the establishment of neuronal polarity, axonal growth and stabilization, and synapses formation. Anterograde and retrograde axonal transport are supported by various molecular motors, such as kinesins and dynein, and a complex microtubule network. In this review article, we will primarily discuss the molecular mechanisms underlying anterograde axonal transport and its role in neuronal development and maturation, including the establishment of functional synaptic connections. We will then provide an overview of the molecular and cellular perturbations that affect axonal transport and are often associated with axonal degeneration. Lastly, we will relate our current understanding of the role of axonal trafficking concerning anterograde trafficking of mRNA and its involvement in the maintenance of the axonal compartment and disease.
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Affiliation(s)
- Laurent Guillaud
- Molecular Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Sara Emad El-Agamy
- Molecular Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Miki Otsuki
- Molecular Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Marco Terenzio
- Molecular Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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10
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Picci C, Wong VSC, Costa CJ, McKinnon MC, Goldberg DC, Swift M, Alam NM, Prusky GT, Shen S, Kozikowski AP, Willis DE, Langley B. HDAC6 inhibition promotes α-tubulin acetylation and ameliorates CMT2A peripheral neuropathy in mice. Exp Neurol 2020; 328:113281. [PMID: 32147437 DOI: 10.1016/j.expneurol.2020.113281] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 02/24/2020] [Accepted: 03/04/2020] [Indexed: 01/13/2023]
Abstract
Charcot-Marie-Tooth type 2A (CMT2A) peripheral neuropathy, the most common axonal form of CMT, is caused by dominantly inherited point mutations in the Mitofusin 2 (Mfn2) gene. It is characterized by progressive length-dependent degeneration of motor and sensory nerves with corresponding clinical features of motor and sensory impairment. There is no cure for CMT, and therapeutic approaches are limited to physical therapy, orthopedic devices, surgery, and analgesics. In this study we focus on histone deacetylase 6 (HDAC6) as a therapeutic target in a mouse model of mutant MFN2 (MFN2R94Q)-induced CMT2A. We report that these mice display progressive motor and sensory dysfunction as well as a significant decrease in α-tubulin acetylation in distal segments of long peripheral nerves. Treatment with a new, highly selective HDAC6 inhibitor, SW-100, was able to restore α-tubulin acetylation and ameliorate motor and sensory dysfunction when given either prior to or after the onset of symptoms. To confirm HDAC6 is the target for ameliorating the CMT2A phenotype, we show that genetic deletion of Hdac6 in CMT2A mice prevents the development of motor and sensory dysfunction. Our findings suggest α-tubulin acetylation defects in distal parts of nerves as a pathogenic mechanism and HDAC6 as a therapeutic target for CMT2A.
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Affiliation(s)
- Cristina Picci
- The Burke Neurological Institute, White Plains, NY, 10605, USA; Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA; School of Health, The University of Waikato, Private Bag 3105, Hamilton, New Zealand.
| | - Victor S C Wong
- The Burke Neurological Institute, White Plains, NY, 10605, USA; Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | | | - Marion C McKinnon
- School of Health, The University of Waikato, Private Bag 3105, Hamilton, New Zealand
| | | | - Michelle Swift
- The Burke Neurological Institute, White Plains, NY, 10605, USA
| | - Nazia M Alam
- The Burke Neurological Institute, White Plains, NY, 10605, USA; Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065, USA
| | - Glen T Prusky
- The Burke Neurological Institute, White Plains, NY, 10605, USA; Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065, USA
| | - Sida Shen
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Alan P Kozikowski
- StarWise Therapeutics LLC, 2020 N Lincoln Park West, Chicago, IL 60614, USA
| | - Dianna E Willis
- The Burke Neurological Institute, White Plains, NY, 10605, USA; Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA.
| | - Brett Langley
- The Burke Neurological Institute, White Plains, NY, 10605, USA; Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA; School of Health, The University of Waikato, Private Bag 3105, Hamilton, New Zealand.
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11
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Shen S, Kozikowski AP. A patent review of histone deacetylase 6 inhibitors in neurodegenerative diseases (2014-2019). Expert Opin Ther Pat 2020; 30:121-136. [PMID: 31865813 PMCID: PMC6950832 DOI: 10.1080/13543776.2019.1708901] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 12/20/2019] [Indexed: 12/24/2022]
Abstract
Introduction: Histone deacetylase 6 (HDAC6) is unique in comparison with other zinc-dependent HDAC family members. An increasing amount of evidence from clinical and preclinical research demonstrates the potential of HDAC6 inhibition as an effective therapeutic approach for the treatment of cancer, autoimmune diseases, as well as neurological disorders. The recently disclosed crystal structures of HDAC6-ligand complexes offer further means for achieving pharmacophore refinement, thus further accelerating the pace of HDAC6 inhibitor discovery in the last few years.Area covered: This review summarizes the latest clinical status of HDAC6 inhibitors, discusses pharmacological applications of selective HDAC6 inhibitors in neurodegenerative diseases, and describes the patent applications dealing with HDAC6 inhibitors from 2014-2019 that have not been reported in research articles.Expert opinion: Phenylhydroxamate has proven a very useful scaffold in the discovery of potent and selective HDAC6 inhibitors. However, weaknesses of the hydroxamate function such as metabolic instability and mutagenic potential limit its application in the neurological field, where long-term administration is required. The recent invention of oxadiazole-based ligands by pharmaceutical companies may provide a new opportunity to optimize the druglike properties of HDAC6 inhibitors for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Sida Shen
- Departments of Chemistry, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, and Center for Developmental Therapeutics, Northwestern University, Evanston, Illinois, United States
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12
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Brindisi M, Saraswati AP, Brogi S, Gemma S, Butini S, Campiani G. Old but Gold: Tracking the New Guise of Histone Deacetylase 6 (HDAC6) Enzyme as a Biomarker and Therapeutic Target in Rare Diseases. J Med Chem 2019; 63:23-39. [PMID: 31415174 DOI: 10.1021/acs.jmedchem.9b00924] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Epigenetic regulation orchestrates many cellular processes and greatly influences key disease mechanisms. Histone deacetylase (HDAC) enzymes play a crucial role either as biomarkers or therapeutic targets owing to their involvement in specific pathophysiological pathways. Beyond their well-characterized role as histone modifiers, HDACs also interact with several nonhistone substrates and their increased expression has been highlighted in specific diseases. The HDAC6 isoform, due to its unique cytoplasmic localization, modulates the acetylation status of tubulin, HSP90, TGF-β, and peroxiredoxins. HDAC6 also exerts noncatalytic activities through its interaction with ubiquitin. Both catalytic and noncatalytic functions of HDACs are being actively studied in the field of specific rare disorders beyond the well-established role in carcinogenesis. This Perspective outlines the application of HDAC(6) inhibitors in rare diseases, such as Rett syndrome, inherited retinal disorders, idiopathic pulmonary fibrosis, and Charcot-Marie-Tooth disease, highlighting their therapeutic potential as innovative and targeted disease-modifying agents.
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Affiliation(s)
- Margherita Brindisi
- Department of Pharmacy, Department of Excellence 2018-2022 , University of Naples Federico II , Via D. Montesano 49 , I-80131 Naples , Italy
| | - A Prasanth Saraswati
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022 , University of Siena , via Aldo Moro 2 , 53100 , Siena , Italy
| | - Simone Brogi
- Department of Pharmacy , University of Pisa , via Bonanno 6 , 56126 , Pisa , Italy
| | - Sandra Gemma
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022 , University of Siena , via Aldo Moro 2 , 53100 , Siena , Italy
| | - Stefania Butini
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022 , University of Siena , via Aldo Moro 2 , 53100 , Siena , Italy
| | - Giuseppe Campiani
- Department of Biotechnology, Chemistry and Pharmacy, Department of Excellence 2018-2022 , University of Siena , via Aldo Moro 2 , 53100 , Siena , Italy
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Chelban V, Wilson MP, Warman Chardon J, Vandrovcova J, Zanetti MN, Zamba‐Papanicolaou E, Efthymiou S, Pope S, Conte MR, Abis G, Liu Y, Tribollet E, Haridy NA, Botía JA, Ryten M, Nicolaou P, Minaidou A, Christodoulou K, Kernohan KD, Eaton A, Osmond M, Ito Y, Bourque P, Jepson JEC, Bello O, Bremner F, Cordivari C, Reilly MM, Foiani M, Heslegrave A, Zetterberg H, Heales SJR, Wood NW, Rothman JE, Boycott KM, Mills PB, Clayton PT, Houlden H. PDXK mutations cause polyneuropathy responsive to pyridoxal 5'-phosphate supplementation. Ann Neurol 2019; 86:225-240. [PMID: 31187503 PMCID: PMC6772106 DOI: 10.1002/ana.25524] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 06/05/2019] [Accepted: 06/07/2019] [Indexed: 12/30/2022]
Abstract
OBJECTIVE To identify disease-causing variants in autosomal recessive axonal polyneuropathy with optic atrophy and provide targeted replacement therapy. METHODS We performed genome-wide sequencing, homozygosity mapping, and segregation analysis for novel disease-causing gene discovery. We used circular dichroism to show secondary structure changes and isothermal titration calorimetry to investigate the impact of variants on adenosine triphosphate (ATP) binding. Pathogenicity was further supported by enzymatic assays and mass spectroscopy on recombinant protein, patient-derived fibroblasts, plasma, and erythrocytes. Response to supplementation was measured with clinical validated rating scales, electrophysiology, and biochemical quantification. RESULTS We identified biallelic mutations in PDXK in 5 individuals from 2 unrelated families with primary axonal polyneuropathy and optic atrophy. The natural history of this disorder suggests that untreated, affected individuals become wheelchair-bound and blind. We identified conformational rearrangement in the mutant enzyme around the ATP-binding pocket. Low PDXK ATP binding resulted in decreased erythrocyte PDXK activity and low pyridoxal 5'-phosphate (PLP) concentrations. We rescued the clinical and biochemical profile with PLP supplementation in 1 family, improvement in power, pain, and fatigue contributing to patients regaining their ability to walk independently during the first year of PLP normalization. INTERPRETATION We show that mutations in PDXK cause autosomal recessive axonal peripheral polyneuropathy leading to disease via reduced PDXK enzymatic activity and low PLP. We show that the biochemical profile can be rescued with PLP supplementation associated with clinical improvement. As B6 is a cofactor in diverse essential biological pathways, our findings may have direct implications for neuropathies of unknown etiology characterized by reduced PLP levels. ANN NEUROL 2019;86:225-240.
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Affiliation(s)
- Viorica Chelban
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Neurology and NeurosurgeryInstitute of Emergency MedicineChisinauMoldova
| | - Matthew P. Wilson
- Genetics and Genomic MedicineUniversity College London Great Ormond Street Institute of Child HealthLondonUnited Kingdom
| | - Jodi Warman Chardon
- Department of Medicine (Neurology)University of OttawaOttawaOntarioCanada
- Ottawa Hospital Research InstituteOttawaOntarioCanada
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
| | - Jana Vandrovcova
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - M. Natalia Zanetti
- Department of Clinical and Experimental EpilepsyUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Eleni Zamba‐Papanicolaou
- Cyprus Institute of Neurology and GeneticsNicosiaCyprus
- Cyprus School of Molecular MedicineNicosiaCyprus
| | - Stephanie Efthymiou
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Simon Pope
- Neurometabolic Unit, National Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - Maria R. Conte
- Randall Centre of Cell and Molecular Biophysics, School of Basic and Medical BiosciencesKing's College LondonLondonUnited Kingdom
| | - Giancarlo Abis
- Randall Centre of Cell and Molecular Biophysics, School of Basic and Medical BiosciencesKing's College LondonLondonUnited Kingdom
| | - Yo‐Tsen Liu
- Department of NeurologyNeurological Institute, Taipei Veterans General HospitalTaipeiTaiwan
- National Yang‐Ming University School of MedicineTaipeiTaiwan
- Institute of Brain Science, National Yang‐Ming UniversityTaipeiTaiwan
| | - Eloise Tribollet
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Nourelhoda A. Haridy
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Neurology and PsychiatryAssiut University Hospital, Faculty of MedicineAsyutEgypt
| | - Juan A. Botía
- Reta Lila Weston Research LaboratoriesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Information and Communications EngineeringUniversity of MurciaMurciaSpain
| | - Mina Ryten
- Reta Lila Weston Research LaboratoriesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Medical & Molecular GeneticsKing's College London, Guy's HospitalLondonUnited Kingdom
| | - Paschalis Nicolaou
- Cyprus Institute of Neurology and GeneticsNicosiaCyprus
- Cyprus School of Molecular MedicineNicosiaCyprus
| | - Anna Minaidou
- Cyprus Institute of Neurology and GeneticsNicosiaCyprus
- Cyprus School of Molecular MedicineNicosiaCyprus
| | - Kyproula Christodoulou
- Cyprus Institute of Neurology and GeneticsNicosiaCyprus
- Cyprus School of Molecular MedicineNicosiaCyprus
| | - Kristin D. Kernohan
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
- Newborn Screening Ontario, Children's Hospital of Eastern OntarioOttawaOntarioCanada
| | - Alison Eaton
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
| | - Matthew Osmond
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
| | - Yoko Ito
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
| | - Pierre Bourque
- Department of Medicine (Neurology)University of OttawaOttawaOntarioCanada
- Ottawa Hospital Research InstituteOttawaOntarioCanada
| | - James E. C. Jepson
- Department of Clinical and Experimental EpilepsyUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Oscar Bello
- Department of Clinical and Experimental EpilepsyUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Fion Bremner
- Neuro‐ophthalmology DepartmentNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - Carla Cordivari
- Clinical Neurophysiology DepartmentNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - Mary M. Reilly
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Martha Foiani
- Clinical Neurophysiology DepartmentNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
- Department of Neurodegenerative DiseaseUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
| | - Amanda Heslegrave
- Department of Neurodegenerative DiseaseUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- UK Dementia Research Institute at University College LondonLondonUnited Kingdom
| | - Henrik Zetterberg
- Department of Neurodegenerative DiseaseUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- UK Dementia Research Institute at University College LondonLondonUnited Kingdom
- Clinical Neurochemistry LaboratorySahlgrenska University HospitalMölndalSweden
- Department of Psychiatry and NeurochemistryInstitute of Neuroscience and Physiology, Sahlgrenska Academy at University of GothenburgMölndalSweden
| | - Simon J. R. Heales
- Neurometabolic Unit, National Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - Nicholas W. Wood
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Neurogenetics LaboratoryNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
| | - James E. Rothman
- Department of Clinical and Experimental EpilepsyUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Department of Cell BiologyYale School of MedicineNew HavenCT
| | - Kym M. Boycott
- Children's Hospital of Eastern Ontario Research Institute, University of OttawaOttawaOntarioCanada
| | - Philippa B. Mills
- Genetics and Genomic MedicineUniversity College London Great Ormond Street Institute of Child HealthLondonUnited Kingdom
| | - Peter T. Clayton
- Genetics and Genomic MedicineUniversity College London Great Ormond Street Institute of Child HealthLondonUnited Kingdom
| | - Henry Houlden
- Department of Neuromuscular DiseasesUniversity College London Queen Square Institute of NeurologyLondonUnited Kingdom
- Neurogenetics LaboratoryNational Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
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14
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Kinesins: Motor Proteins as Novel Target for the Treatment of Chronic Pain. Mol Neurobiol 2018; 56:3854-3864. [DOI: 10.1007/s12035-018-1327-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 08/21/2018] [Indexed: 10/28/2022]
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15
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DHTKD1 Deficiency Causes Charcot-Marie-Tooth Disease in Mice. Mol Cell Biol 2018; 38:MCB.00085-18. [PMID: 29661920 DOI: 10.1128/mcb.00085-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 04/08/2018] [Indexed: 01/20/2023] Open
Abstract
DHTKD1, a part of 2-ketoadipic acid dehydrogenase complex, is involved in lysine and tryptophan catabolism. Mutations in DHTKD1 block the metabolic pathway and cause 2-aminoadipic and 2-oxoadipic aciduria (AMOXAD), an autosomal recessive inborn metabolic disorder. In addition, a nonsense mutation in DHTKD1 that we identified previously causes Charcot-Marie-Tooth disease (CMT) type 2Q, one of the most common inherited neurological disorders affecting the peripheral nerves in the musculature. However, the comprehensive molecular mechanism underlying CMT2Q remains elusive. Here, we show that Dhtkd1-/- mice mimic the major aspects of CMT2 phenotypes, characterized by progressive weakness and atrophy in the distal parts of limbs with motor and sensory dysfunctions, which are accompanied with decreased nerve conduction velocity. Moreover, DHTKD1 deficiency causes severe metabolic abnormalities and dramatically increased levels of 2-ketoadipic acid (2-KAA) and 2-aminoadipic acid (2-AAA) in urine. Further studies revealed that both 2-KAA and 2-AAA could stimulate insulin biosynthesis and secretion. Subsequently, elevated insulin regulates myelin protein zero (Mpz) transcription in Schwann cells via upregulating the expression of early growth response 2 (Egr2), leading to myelin structure damage and axonal degeneration. Finally, 2-AAA-fed mice do reproduce phenotypes similar to CMT2Q phenotypes. In conclusion, we have demonstrated that loss of DHTKD1 causes CMT2Q-like phenotypes through dysregulation of Mpz mRNA and protein zero (P0) which are closely associated with elevated DHTKD1 substrate and insulin levels. These findings further indicate an important role of metabolic disorders in addition to mitochondrial insufficiency in the pathogenesis of peripheral neuropathies.
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16
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Kalmar B, Innes A, Wanisch K, Kolaszynska AK, Pandraud A, Kelly G, Abramov AY, Reilly MM, Schiavo G, Greensmith L. Mitochondrial deficits and abnormal mitochondrial retrograde axonal transport play a role in the pathogenesis of mutant Hsp27-induced Charcot Marie Tooth Disease. Hum Mol Genet 2018; 26:3313-3326. [PMID: 28595321 PMCID: PMC5808738 DOI: 10.1093/hmg/ddx216] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 05/25/2017] [Indexed: 11/26/2022] Open
Abstract
Mutations in the small heat shock protein Hsp27, encoded by the HSPB1 gene, have been shown to cause Charcot Marie Tooth Disease type 2 (CMT-2) or distal hereditary motor neuropathy (dHMN). Protein aggregation and axonal transport deficits have been implicated in the disease. In this study, we conducted analysis of bidirectional movements of mitochondria in primary motor neuron axons expressing wild type and mutant Hsp27. We found significantly slower retrograde transport of mitochondria in Ser135Phe, Pro39Leu and Arg140Gly mutant Hsp27 expressing motor neurons than in wild type Hsp27 neurons, although anterograde movement velocities remained normal. Retrograde transport of other important cargoes, such as the p75 neurotrophic factor receptor was minimally altered in mutant Hsp27 neurons, implicating that axonal transport deficits primarily affect mitochondria and the axonal transport machinery itself is less affected. Investigation of mitochondrial function revealed a decrease in mitochondrial membrane potential in mutant Hsp27 expressing motor axons, as well as a reduction in mitochondrial complex 1 activity, increased vulnerability of mitochondria to mitochondrial stressors, leading to elevated superoxide release and reduced mitochondrial glutathione (GSH) levels, although cytosolic GSH remained normal. This mitochondrial redox imbalance in mutant Hsp27 motor neurons is likely to cause low level of oxidative stress, which in turn will contribute to, and indeed may be the underlying cause of the deficits in mitochondrial axonal transport. Together, these findings suggest that the mitochondrial abnormalities in mutant Hsp27-induced neuropathies may be a primary cause of pathology, leading to further deficits in the mitochondrial axonal transport and onset of disease.
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Affiliation(s)
| | - Amy Innes
- Sobell Department of Motor Neuroscience and Movement Disorders.,MRC Centre for Neuromuscular Diseases
| | - Klaus Wanisch
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square House, Queen Square, London WC1N 3BG, UK
| | | | - Amelie Pandraud
- MRC Centre for Neuromuscular Diseases.,Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square House, Queen Square, London WC1N 3BG, UK
| | - Gavin Kelly
- Bioinformatics and Biostatistics Science Technology Platform, The Francis Crick Institute, London NW1?1AT, UK
| | | | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases.,Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square House, Queen Square, London WC1N 3BG, UK
| | | | - Linda Greensmith
- Sobell Department of Motor Neuroscience and Movement Disorders.,MRC Centre for Neuromuscular Diseases
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17
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Chandhok G, Lazarou M, Neumann B. Structure, function, and regulation of mitofusin-2 in health and disease. Biol Rev Camb Philos Soc 2017; 93:933-949. [PMID: 29068134 PMCID: PMC6446723 DOI: 10.1111/brv.12378] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 09/20/2017] [Accepted: 09/22/2017] [Indexed: 12/12/2022]
Abstract
Mitochondria are highly dynamic organelles that constantly migrate, fuse, and divide to regulate their shape, size, number, and bioenergetic function. Mitofusins (Mfn1/2), optic atrophy 1 (OPA1), and dynamin-related protein 1 (Drp1), are key regulators of mitochondrial fusion and fission. Mutations in these molecules are associated with severe neurodegenerative and non-neurological diseases pointing to the importance of functional mitochondrial dynamics in normal cell physiology. In recent years, significant progress has been made in our understanding of mitochondrial dynamics, which has raised interest in defining the physiological roles of key regulators of fusion and fission and led to the identification of additional functions of Mfn2 in mitochondrial metabolism, cell signalling, and apoptosis. In this review, we summarize the current knowledge of the structural and functional properties of Mfn2 as well as its regulation in different tissues, and also discuss the consequences of aberrant Mfn2 expression.
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Affiliation(s)
- Gursimran Chandhok
- Department of Anatomy and Developmental Biology, and Neuroscience Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria 3800, Australia
| | - Michael Lazarou
- Department of Biochemistry and Molecular Biology, and Neuroscience Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria 3800, Australia
| | - Brent Neumann
- Department of Anatomy and Developmental Biology, and Neuroscience Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria 3800, Australia
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18
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HSPB1 mutations causing hereditary neuropathy in humans disrupt non-cell autonomous protection of motor neurons. Exp Neurol 2017; 297:101-109. [PMID: 28797631 DOI: 10.1016/j.expneurol.2017.08.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/22/2017] [Accepted: 08/06/2017] [Indexed: 12/12/2022]
Abstract
Heat shock protein beta-1 (HSPB1), is a ubiquitously expressed, multifunctional protein chaperone. Mutations in HSPB1 result in the development of a late-onset, distal hereditary motor neuropathy type II (dHMN) and axonal Charcot-Marie Tooth disease with sensory involvement (CMT2F). The functional consequences of HSPB1 mutations associated with hereditary neuropathy are unknown. HSPB1 also displays neuroprotective properties in many neuronal disease models, including the motor neuron disease amyotrophic lateral sclerosis (ALS). HSPB1 is upregulated in SOD1-ALS animal models during disease progression, predominately in glial cells. Glial cells are known to contribute to motor neuron loss in ALS through a non-cell autonomous mechanism. In this study, we examined the non-cell autonomous role of wild type and mutant HSPB1 in an astrocyte-motor neuron co-culture model system of ALS. Astrocyte-specific overexpression of wild type HSPB1 was sufficient to attenuate SOD1(G93A) astrocyte-mediated toxicity in motor neurons, whereas, overexpression of mutHSPB1 failed to ameliorate motor neuron toxicity. Expression of a phosphomimetic HSPB1 mutant in SOD1(G93A) astrocytes also reduced toxicity to motor neurons, suggesting that phosphorylation may contribute to HSPB1 mediated-neuroprotection. These data provide evidence that astrocytic HSPB1 expression may play a central role in motor neuron health and maintenance.
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19
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Holt DE, Brown DC, Henthorn PS. Evaluation of the dynactin 1 gene in Leonbergers and Labrador Retrievers with laryngeal paralysis. Am J Vet Res 2017; 77:1114-20. [PMID: 27668583 DOI: 10.2460/ajvr.77.10.1114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To sequence exons and splice consensus sites of the dynactin subunit 1 (DCTN1) gene in Leonbergers and Labrador Retrievers with clinical laryngeal paralysis. ANIMALS 5 unrelated Leonbergers with laryngeal paralysis, 2 clinically normal Leonbergers, 7 unrelated Labrador Retrievers with laryngeal paralysis, and 2 clinically normal Labrador Retrievers. PROCEDURES Primers were designed for the entire coding regions of the DCTN1 gene, a noncoding exon at the 5´ end of the gene, and a 900-bp single-nucleotide polymorphism (SNP)-rich region located 17 kb upstream of the DCTN1 gene by use of the CanFam3 assembly of the canine genome sequence. Sequences were generated and compared between clinically normal and affected dogs. The SNPs flanking the DCTN1 gene as well as a previously identified nonsynonymous SNP in exon 32 were genotyped in affected and clinically normal Leonbergers and Labrador Retrievers. RESULTS None of the affected dogs were homozygous for any mutation affecting coding regions or splicing consensus sequences. Of the 16 dogs tested for the missense SNP in exon 32, all were homozygous for the reference allele, except for 2 affected and 1 clinically normal Labrador Retriever and 1 clinically normal Leonberger. The DCTN1 gene sequences (5 dogs) and haplotypes of polymorphic markers surrounding the DCTN1 gene (all dogs) were not consistent with the hypothesis that laryngeal paralysis was associated with inheritance of the same DCTN1 disease-causing allele within all Labrador Retrievers or Leonbergers evaluated. CONCLUSIONS AND CLINICAL RELEVANCE Mutations in the DCTN1 gene did not appear to cause laryngeal paralysis in Leonbergers or Labrador Retrievers.
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20
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Poole JL, Huffman M, Hunter A, Mares C, Siegel P. Reliability and validity of the Manual Ability Measure-36 in persons with Charcot-Marie-Tooth disease. J Hand Ther 2016; 28:364-7; quiz 368. [PMID: 26318522 DOI: 10.1016/j.jht.2015.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 03/18/2015] [Accepted: 04/23/2015] [Indexed: 02/03/2023]
Abstract
STUDY DESIGN Descriptive, clinical measurement. INTRODUCTION Charcot-Marie-Tooth disease (CMT) is a genetic disorder that results in demyelination or axonal degeneration in peripheral nerves. Characteristic symptoms include decreased muscle strength and sensation, particularly in the hands and feet. PURPOSE Examine the reliability and validity of the Manual Ability Measure (MAM-36), a 36-item self-report questionnaire specific to hand function, in persons with CMT. METHODS Fourteen participants with CMT completed the MAM-36 at two points one week apart. Participants were also administered performance-based tests for grip and pinch strength, dexterity, and sensation. RESULTS The test-retest intraclass correlation coefficient (ICC) for the MAM-36 was 0.96. Pearson correlation coefficients showed fair to good relationships (r = 0.41-0.64) between the MAM-36 scores and most of the performance tests. CONCLUSION The MAM-36 is a reliable and valid assessment tool for measuring hand function during everyday tasks in persons with CMT. LEVEL OF EVIDENCE IIb.
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Affiliation(s)
- Janet L Poole
- University of New Mexico, Occupational Therapy Graduate Program, Albuquerque, NM, USA.
| | | | | | | | - Patricia Siegel
- University of New Mexico, Occupational Therapy Graduate Program, Albuquerque, NM, USA
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Neupauerová J, Grečmalová D, Seeman P, Laššuthová P. Massively Parallel Sequencing Detected a Mutation in the MFN2 Gene Missed by Sanger Sequencing Due to a Primer Mismatch on an SNP Site. Ann Hum Genet 2016; 80:182-6. [PMID: 26916081 DOI: 10.1111/ahg.12151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 12/22/2015] [Accepted: 01/05/2016] [Indexed: 11/25/2022]
Abstract
We describe a patient with early onset severe axonal Charcot-Marie-Tooth disease (CMT2) with dominant inheritance, in whom Sanger sequencing failed to detect a mutation in the mitofusin 2 (MFN2) gene because of a single nucleotide polymorphism (rs2236057) under the PCR primer sequence. The severe early onset phenotype and the family history with severely affected mother (died after delivery) was very suggestive of CMT2A and this suspicion was finally confirmed by a MFN2 mutation. The mutation p.His361Tyr was later detected in the patient by massively parallel sequencing with a gene panel for hereditary neuropathies. According to this information, new primers for amplification and sequencing were designed which bind away from the polymorphic sites of the patient's DNA. Sanger sequencing with these new primers then confirmed the heterozygous mutation in the MFN2 gene in this patient. This case report shows that massively parallel sequencing may in some rare cases be more sensitive than Sanger sequencing and highlights the importance of accurate primer design which requires special attention.
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Affiliation(s)
- Jana Neupauerová
- DNA Laboratory, Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University in Prague and University Hospital Motol, Prague, Czech Republic
| | - Dagmar Grečmalová
- Department of Medical Genetics, University Hospital in Ostrava, Czech Republic
| | - Pavel Seeman
- DNA Laboratory, Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University in Prague and University Hospital Motol, Prague, Czech Republic
| | - Petra Laššuthová
- DNA Laboratory, Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University in Prague and University Hospital Motol, Prague, Czech Republic
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22
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Shen S, Benoy V, Bergman JA, Kalin JH, Frojuello M, Vistoli G, Haeck W, Van Den Bosch L, Kozikowski AP. Bicyclic-Capped Histone Deacetylase 6 Inhibitors with Improved Activity in a Model of Axonal Charcot-Marie-Tooth Disease. ACS Chem Neurosci 2016; 7:240-58. [PMID: 26599234 DOI: 10.1021/acschemneuro.5b00286] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is a disorder of the peripheral nervous system where progressive degeneration of motor and sensory nerves leads to motor problems and sensory loss and for which no pharmacological treatment is available. Recently, it has been shown in a model for the axonal form of CMT that histone deacetylase 6 (HDAC6) can serve as a target for the development of a pharmacological therapy. Therefore, we aimed at developing new selective and activity-specific HDAC6 inhibitors with improved biochemical properties. By utilizing a bicyclic cap as the structural scaffold from which to build upon, we developed several analogues that showed improved potency compared to tubastatin A while maintaining excellent selectivity compared to HDAC1. Further screening in N2a cells examining both the acetylation of α-tubulin and histones narrowed down the library of compounds to three potent and selective HDAC6 inhibitors. In mutant HSPB1-expressing DRG neurons, serving as an in vitro model for CMT2, these inhibitors were able to restore the mitochondrial axonal transport deficits. Combining structure-based development of HDAC6 inhibitors, screening in N2a cells and in a neuronal model for CMT2F, and preliminary ADMET and pharmacokinetic profiles, resulted in the selection of compound 23d that possesses improved biochemical, functional, and druglike properties compared to tubastatin A.
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Affiliation(s)
- Sida Shen
- Drug
Discovery Program, University of Illinois at Chicago, 833 S. Wood
St., Chicago, Illinois 60612, United States
| | - Veronick Benoy
- Laboratory of Neurobiology, Vesalius Research Center (VIB) and Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven, O&N4 Herestraat 49, B-3000 Leuven, Belgium
| | - Joel A. Bergman
- Drug
Discovery Program, University of Illinois at Chicago, 833 S. Wood
St., Chicago, Illinois 60612, United States
| | - Jay H. Kalin
- Drug
Discovery Program, University of Illinois at Chicago, 833 S. Wood
St., Chicago, Illinois 60612, United States
| | - Mariana Frojuello
- Drug
Discovery Program, University of Illinois at Chicago, 833 S. Wood
St., Chicago, Illinois 60612, United States
| | - Giulio Vistoli
- Dipartimento
di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy
| | - Wanda Haeck
- Laboratory of Neurobiology, Vesalius Research Center (VIB) and Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven, O&N4 Herestraat 49, B-3000 Leuven, Belgium
| | - Ludo Van Den Bosch
- Laboratory of Neurobiology, Vesalius Research Center (VIB) and Leuven Research Institute for Neuroscience and Disease (LIND), KU Leuven, O&N4 Herestraat 49, B-3000 Leuven, Belgium
| | - Alan P. Kozikowski
- Drug
Discovery Program, University of Illinois at Chicago, 833 S. Wood
St., Chicago, Illinois 60612, United States
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Boora GK, Kulkarni AA, Kanwar R, Beyerlein P, Qin R, Banck MS, Ruddy KJ, Pleticha J, Lynch CA, Behrens RJ, Züchner S, Loprinzi CL, Beutler AS. Association of the Charcot-Marie-Tooth disease gene ARHGEF10 with paclitaxel induced peripheral neuropathy in NCCTG N08CA (Alliance). J Neurol Sci 2015; 357:35-40. [PMID: 26143528 DOI: 10.1016/j.jns.2015.06.056] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 05/23/2015] [Accepted: 06/25/2015] [Indexed: 11/26/2022]
Abstract
The predisposition of patients to develop polyneuropathy in response to toxic exposure may have a genetic basis. The previous study Alliance N08C1 found an association of the Charcot-Marie-Tooth disease (CMT) gene ARHGEF10 with paclitaxel chemotherapy induced peripheral neuropathy (CIPN) related to the three non-synonymous, recurrent single nucleotide variants (SNV), whereby rs9657362 had the strongest effect, and rs2294039 and rs17683288 contributed only weakly. In the present report, Alliance N08CA was chosen to attempt to replicate the above finding. N08CA was chosen because it is the methodologically most similar study (to N08C1) performed in the CIPN field to date. N08CA enrolled patients receiving the neurotoxic chemotherapy agent paclitaxel. Polyneuropathy was assessed by serial repeat administration of the previously validated patient reported outcome instrument CIPN20. A study-wide, Rasch type model was used to perform extreme phenotyping in n=138 eligible patients from which "cases" and "controls" were selected for genetic analysis of SNV performed by TaqMan PCR. A significant association of ARHGEF10 with CIPN was found under the pre-specified primary endpoint, with a significance level of p=0.024. As in the original study, the strongest association of a single SNV was seen for rs9657362 (odds ratio=3.56, p=0.018). To further compare results across the new and the previous study, a statistical "classifier" was tested, which achieved a ROC area under the curve of 0.60 for N08CA and 0.66 for N08C1, demonstrating good agreement. Retesting of the primary endpoint of N08C1 in the replication study N08CA validated the association of ARHGEF10 with CIPN.
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Affiliation(s)
| | | | - Rahul Kanwar
- Department of Oncology, Mayo Clinic, Rochester, MN, USA
| | - Peter Beyerlein
- Department of Diagnostic Bioinformatics, Technische Hochschule Wildau, Wildau, Germany
| | - Rui Qin
- Alliance Statistics and Data Center, Mayo Clinic, Rochester, MN, USA
| | | | | | | | | | | | - Stephan Züchner
- Department of Human Genetics and Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA
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Verma A. Next-generation sequencing and genetic diagnosis of Charcot-Marie-Tooth disease. Ann Indian Acad Neurol 2014; 17:383-6. [PMID: 25506157 PMCID: PMC4251009 DOI: 10.4103/0972-2327.144004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 05/08/2014] [Accepted: 05/23/2014] [Indexed: 12/15/2022] Open
Abstract
Over 70 different Charcot-Marie-Tooth disease (CMT)–associated genes have now been discovered and their number is growing. Conventional genetic testing for all CMT genes is cumbersome, expensive, and impractical in an individual patient. Next-generation sequencing (NGS) technology allows cost-effective sequencing of large scale DNA, even entire exome (coding sequences) or whole genome and thus, NGS platform can be employed to effectively target a large number or all CMT-related genes for accurate diagnosis. This overview discusses how NGS can be strategically used for genetic diagnosis in patients with CMT or unexplained neuropathy. A comment is made to combine simple clinical and electrophysiological algorithm to assign patients to major CMT subtypes and then employ NGS to screen for all known mutations in the subtype-specific CMT gene panel.
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Affiliation(s)
- Ashok Verma
- Department of Neurology, University of Miami Miller School of Medicine, Miami, Florida, USA
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TRPV4 channel activity is modulated by direct interaction of the ankyrin domain to PI(4,5)P₂. Nat Commun 2014; 5:4994. [PMID: 25256292 DOI: 10.1038/ncomms5994] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 08/15/2014] [Indexed: 11/09/2022] Open
Abstract
Mutations in the ankyrin repeat domain (ARD) of TRPV4 are responsible for several channelopathies, including Charcot-Marie-Tooth disease type 2C and congenital distal and scapuloperoneal spinal muscular atrophy. However, the molecular pathogenesis mediated by these mutations remains elusive, mainly due to limited understanding of the TRPV4 ARD function. Here we show that phosphoinositide binding to the TRPV4 ARD leads to suppression of the channel activity. Among the phosphoinositides, phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) most potently binds to the TRPV4 ARD. The crystal structure of the TRPV4 ARD in complex with inositol-1,4,5-trisphosphate, the head-group of PI(4,5)P2, and the molecular-dynamics simulations revealed the PI(4,5)P2-binding amino-acid residues. The TRPV4 channel activities were increased by titration or hydrolysis of membrane PI(4,5)P2. Notably, disease-associated TRPV4 mutations that cause a gain-of-function phenotype abolished PI(4,5)P2 binding and PI(4,5)P2 sensitivity. These findings identify TRPV4 ARD as a lipid-binding domain in which interactions with PI(4,5)P2 normalize the channel activity in TRPV4.
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Beutler AS, Kulkarni AA, Kanwar R, Klein CJ, Therneau TM, Qin R, Banck MS, Boora GK, Ruddy KJ, Wu Y, Smalley RL, Cunningham JM, Le-Lindqwister NA, Beyerlein P, Schroth GP, Windebank AJ, Züchner S, Loprinzi CL. Sequencing of Charcot-Marie-Tooth disease genes in a toxic polyneuropathy. Ann Neurol 2014; 76:727-37. [PMID: 25164601 DOI: 10.1002/ana.24265] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 08/14/2014] [Accepted: 08/22/2014] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Mutations in Charcot-Marie-Tooth disease (CMT) genes are the cause of rare familial forms of polyneuropathy. Whether allelic variability in CMT genes is also associated with common forms of polyneuropathy-considered "acquired" in medical parlance-is unknown. Chemotherapy-induced peripheral neuropathy (CIPN) occurs commonly in cancer patients and is individually unpredictable. We used CIPN as a clinical model to investigate the association of non-CMT polyneuropathy with CMT genes. METHODS A total of 269 neurologically asymptomatic cancer patients were enrolled in the clinical trial Alliance N08C1 to receive the neurotoxic drug paclitaxel, while undergoing prospective assessments for polyneuropathy. Forty-nine CMT genes were analyzed by targeted massively parallel sequencing of genomic DNA from patient blood. RESULTS A total of 119 (of 269) patients were identified from the 2 ends of the polyneuropathy phenotype distribution: patients that were most and least susceptible to paclitaxel polyneuropathy. The CMT gene PRX was found to be deleteriously mutated in patients who were susceptible to CIPN but not in controls (p = 8 × 10(-3)). Genetic variation in another CMT gene, ARHGEF10, was highly significantly associated with CIPN (p = 5 × 10(-4)). Three nonsynonymous recurrent single nucleotide variants contributed to the ARHGEF10 signal: rs9657362, rs2294039, and rs17683288. Of these, rs9657362 had the strongest effect (odds ratio = 4.8, p = 4 × 10(-4)). INTERPRETATION The results reveal an association of CMT gene allelic variability with susceptibility to CIPN. The findings raise the possibility that other acquired polyneuropathies may also be codetermined by genetic etiological factors, of which some may be related to genes already known to cause the phenotypically related Mendelian disorders of CMT.
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Affiliation(s)
- Andreas S Beutler
- Department of Oncology, Mayo Clinic, Rochester, MN; Cancer Center, Mayo Clinic, Rochester, MN
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Abstract
Ophthalmic findings are common features of neurodegenerative disorders and, in addition to being clinically important, have emerged as potentially useful biomarkers of disease progression in several conditions. Clinically, these visual system abnormalities can be a clue to diagnosis, as well as being a prominent cause of disability in affected patients. In this Review, we describe the various afferent visual system and other ophthalmic features of inherited neurodegenerative disorders, including the muscular dystrophies, Friedreich ataxia, the spinocerebellar ataxias, hereditary spastic paraplegia, Charcot-Marie-Tooth disease, and other conditions. We focus on the expanding role of optical coherence tomography in diagnostic imaging of the retina and optic nerve head, and the possible use of ophthalmic findings as biomarkers of disease severity in hereditary neurodegenerative disorders. In addition, we discuss the ophthalmic manifestations and treatment implications of mitochondrial dysfunction, which is a feature of many inherited neurodegenerative diseases.
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Hong YB, Lee JH, Park JM, Choi YR, Hyun YS, Yoon BR, Yoo JH, Koo H, Jung SC, Chung KW, Choi BO. A compound heterozygous mutation in HADHB gene causes an axonal Charcot-Marie-tooth disease. BMC MEDICAL GENETICS 2013; 14:125. [PMID: 24314034 PMCID: PMC4029087 DOI: 10.1186/1471-2350-14-125] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 11/28/2013] [Indexed: 12/31/2022]
Abstract
Background Charcot-Marie-Tooth disease (CMT) is a heterogeneous disorder of the peripheral nervous system. So far, mutations in hydroxyacyl-CoA dehydrogenase/3-ketoacyl-CoA thiolase/enoyl-CoA hydratase (trifunctional protein), beta subunit (HADHB) gene exhibit three distinctive phenotypes: severe neonatal presentation with cardiomyopathy, hepatic form with recurrent hypoketotic hypoglycemia, and later-onset axonal sensory neuropathy with episodic myoglobinuria. Methods To identify the causative and characterize clinical features of a Korean family with motor and sensory neuropathies, whole exome study (WES), histopathologic study of distal sural nerve, and lower limb MRIs were performed. Results WES revealed that a compound heterozygous mutation in HADHB is the causative of the present patients. The patients exhibited an early-onset axonal sensorimotor neuropathy without episodic myoglobinuria, and showed typical clinical and electrophysiological features of CMT including predominant distal muscle weakness and atrophy. Histopathologic findings of sural nerve were compatible with an axonal CMT neuropathy. Furthermore, they didn’t exhibit any other symptoms of the previously reported HADHB patients. Conclusions These data implicate that mutation in HADHB gene can also cause early-onset axonal CMT instead of typical manifestations in mitochondrial trifunctional protein (MTP) deficiency. Therefore, this study is the first report of a new subtype of autosomal recessive axonal CMT by a compound heterozygous mutation in HADHB, and will expand the clinical and genetic spectrum of HADHB.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Ki Wha Chung
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong Gangnam-Gu, Seoul 135-710, Korea.
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Lépinoux-Chambaud C, Eyer J. Review on intermediate filaments of the nervous system and their pathological alterations. Histochem Cell Biol 2013; 140:13-22. [PMID: 23749407 DOI: 10.1007/s00418-013-1101-1] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/23/2013] [Indexed: 11/28/2022]
Abstract
Intermediate filaments (IFs) of the nervous system, including neurofilaments, α-internexin, glial fibrillary acidic protein, synemin, nestin, peripherin and vimentin, are finely expressed following elaborated cell, tissue and developmental specific patterns. A common characteristic of several neurodegenerative diseases is the abnormal accumulation of neuronal IFs in cell bodies or along the axon, often associated with impairment of the axonal transport and degeneration of neurons. In this review, we also present several perturbations of IF metabolism and organization associated with neurodegenerative disorders. Such modifications could represent strong markers of neuronal damages. Moreover, recent data suggest that IFs represent potential biomarkers to determine the disease progression or the differential stages of a neuronal disorder. Finally, recent investigations on IF expression and function in cancer provide evidence that they may be useful as markers, or targets of brain tumours, especially high-grade glioma. A better knowledge of the molecular mechanisms of IF alterations, combined to neuroimaging, is essential to improve diagnosis and therapeutic strategies of such neurodegenerative diseases and glioma.
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Affiliation(s)
- Claire Lépinoux-Chambaud
- Laboratoire Neurobiologie and Transgenese, LUNAM, UPRES EA-3143, Centre Hospitalier Universitaire, Bâtiment IBS-IRIS, Université d'Angers, 49033, Angers, France
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30
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Schreiber S, Oldag A, Kornblum C, Kollewe K, Kropf S, Schoenfeld A, Feistner H, Jakubiczka S, Kunz WS, Scherlach C, Tempelmann C, Mawrin C, Dengler R, Schreiber F, Goertler M, Vielhaber S. Sonography of the median nerve in CMT1A, CMT2A, CMTX, and HNPP. Muscle Nerve 2013; 47:385-95. [PMID: 23381770 DOI: 10.1002/mus.23681] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2012] [Indexed: 02/06/2023]
Abstract
INTRODUCTION In this study we compare the ultrasound features in the median nerve in patients with different types of Charcot-Marie-Tooth (CMT) disease and hereditary neuropathies with liability to pressure palsies (HNPP) as a typical entrapment neuropathy. METHODS Median nerve ultrasound and conduction studies were performed in patients with CMT1A (n = 12), MFN2-associated CMT2A (n = 7), CMTX (n = 5), and HNPP (n = 5), and in controls (n = 28). RESULTS Median nerve cross-sectional area (CSA) was significantly increased in CMT1A, whereas, in axonal CMT2A, fascicle diameter (FD) was enlarged. CSA correlated with nerve conduction slowing in CMT1A and with axonal loss, as shown by motor and sensory nerve amplitudes in both CMT1A and CMT2A. A relatively low wrist-to-forearm-ratio (WFR <0.8) or a relatively high WFR (>1.8) appeared to be unlikely in MFN2 and Cx32 mutations of CMT2A and CMTX, respectively. CONCLUSION Differences in CSA, FD, and WFR of the median nerve can be helpful in defining subtypes of hereditary neuropathies.
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Affiliation(s)
- Stefanie Schreiber
- Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany.
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d’Ydewalle C, Benoy V, Van Den Bosch L. Charcot-Marie-Tooth disease: Emerging mechanisms and therapies. Int J Biochem Cell Biol 2012; 44:1299-304. [DOI: 10.1016/j.biocel.2012.04.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 04/20/2012] [Accepted: 04/24/2012] [Indexed: 10/28/2022]
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Neural and molecular features on Charcot-Marie-Tooth disease plasticity and therapy. Neural Plast 2012; 2012:171636. [PMID: 22745917 PMCID: PMC3382403 DOI: 10.1155/2012/171636] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/16/2012] [Indexed: 12/21/2022] Open
Abstract
In the peripheral nervous system disorders plasticity is related to changes on the axon and Schwann cell biology, and the synaptic formations and connections, which could be also a focus for therapeutic research. Charcot-Marie-Tooth disease (CMT) represents a large group of inherited peripheral neuropathies that involve mainly both motor and sensory nerves and induce muscular atrophy and weakness. Genetic analysis has identified several pathways and molecular mechanisms involving myelin structure and proper nerve myelination, transcriptional regulation, protein turnover, vesicle trafficking, axonal transport and mitochondrial dynamics. These pathogenic mechanisms affect the continuous signaling and dialogue between the Schwann cell and the axon, having as final result the loss of myelin and nerve maintenance; however, some late onset axonal CMT neuropathies are a consequence of Schwann cell specific changes not affecting myelin. Comprehension of molecular pathways involved in Schwann cell-axonal interactions is likely not only to increase the understanding of nerve biology but also to identify the molecular targets and cell pathways to design novel therapeutic approaches for inherited neuropathies but also for most common peripheral neuropathies. These approaches should improve the plasticity of the synaptic connections at the neuromuscular junction and regenerate cell viability based on improving myelin and axon interaction.
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Abstract
Vigorous transport of cytoplasmic components along axons over substantial distances is crucial for the maintenance of neuron structure and function. The transport of mitochondria, which serves to distribute mitochondrial functions in a dynamic and non-uniform fashion, has attracted special interest in recent years following the discovery of functional connections among microtubules, motor proteins and mitochondria, and their influences on neurodegenerative diseases. Although the motor proteins that drive mitochondrial movement are now well characterized, the mechanisms by which anterograde and retrograde movement are coordinated with one another and with stationary axonal mitochondria are not yet understood. In this Commentary, we review why mitochondria move and how they move, focusing particularly on recent studies of transport regulation, which implicate control of motor activity by specific cell-signaling pathways, regulation of motor access to transport tracks and static microtubule-mitochondrion linkers. A detailed mechanism for modulating anterograde mitochondrial transport has been identified that involves Miro, a mitochondrial Ca(2+)-binding GTPase, which with associated proteins, can bind and control kinesin-1. Elements of the Miro complex also have important roles in mitochondrial fission-fusion dynamics, highlighting questions about the interdependence of biogenesis, transport, dynamics, maintenance and degradation.
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Affiliation(s)
- William M Saxton
- Department of Molecular Cell and Developmental Biology, University of California, Cruz, CA 95060, USA.
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Raturi A, Simmen T. Where the endoplasmic reticulum and the mitochondrion tie the knot: the mitochondria-associated membrane (MAM). BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:213-24. [PMID: 22575682 DOI: 10.1016/j.bbamcr.2012.04.013] [Citation(s) in RCA: 343] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 04/12/2012] [Accepted: 04/25/2012] [Indexed: 01/01/2023]
Abstract
More than a billion years ago, bacterial precursors of mitochondria became endosymbionts in what we call eukaryotic cells today. The true significance of the word "endosymbiont" has only become clear to cell biologists with the discovery that the endoplasmic reticulum (ER) superorganelle dedicates a special domain for the metabolic interaction with mitochondria. This domain, identified in all eukaryotic cell systems from yeast to man and called the mitochondria-associated membrane (MAM), has a distinct proteome, specific tethers on the cytosolic face and regulatory proteins in the ER lumen of the ER. The MAM has distinct biochemical properties and appears as ER tubules closely apposed to mitochondria on electron micrographs. The functions of the MAM range from lipid metabolism and calcium signaling to inflammasome formation. Consistent with these functions, the MAM is enriched in lipid metabolism enzymes and calcium handling proteins. During cellular stress situations, like an altered cellular redox state, the MAM alters its set of regulatory proteins and thus alters MAM functions. Notably, this set prominently comprises ER chaperones and oxidoreductases that connect protein synthesis and folding inside the ER to mitochondrial metabolism. Moreover, ER membranes associated with mitochondria also accommodate parts of the machinery that determines mitochondrial membrane dynamics and connect mitochondria to the cytoskeleton. Together, these exciting findings demonstrate that the physiological interactions between the ER and mitochondria are so bilateral that we are tempted to compare their relationship to the one of a married couple: distinct, but inseparable and certainly dependent on each other. In this paradigm, the MAM stands for the intracellular location where the two organelles tie the knot. Resembling "real life", the happy marriage between the two organelles prevents the onset of diseases that are characterized by disrupted metabolism and decreased lifespan, including neurodegeneration and cancer. This article is part of a Special Issue entitled: Mitochondrial dynamics and physiology.
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Affiliation(s)
- Arun Raturi
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
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Wang K, Long B, Jiao JQ, Wang JX, Liu JP, Li Q, Li PF. miR-484 regulates mitochondrial network through targeting Fis1. Nat Commun 2012; 3:781. [PMID: 22510686 DOI: 10.1038/ncomms1770] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 03/01/2012] [Indexed: 12/27/2022] Open
Abstract
Mitochondria constantly undergo fusion and fission, two necessary processes for the maintenance of organelle fidelity. The abnormal mitochondrial fission participates in the pathogenesis of many diseases, but its regulation remains poorly understood. Here we show that miR-484 can suppress translation of mitochondrial fission protein Fis1, and inhibit Fis1-mediated fission and apoptosis in cardiomyocytes and in the adrenocortical cancer cells. We demonstrate that Fis1 is necessary for mitochondrial fission and apoptosis, and is upregulated during anoxia, whereas miR-484 is downregulated. miR-484 is able to attenuate Fis1 upregulation and mitochondrial fission, by binding to the amino acid coding sequence of Fis1 and inhibiting its translation. In exploring the underlying mechanism of miR-484 downregulation upon apoptosis, we observe that Foxo3a transactivates miR-484 expression. Foxo3a transgenic or knockout mice exhibit, respectively, a high or low level of miR-484 and a reduced or enhanced mitochondrial fission, apoptosis and myocardial infarction. Our data reveal a model of mitochondrial fission regulation by a microRNA.
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Affiliation(s)
- Kun Wang
- Division of Cardiovascular Research, State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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Berciano J, Sevilla T, Casasnovas C, Sivera R, Vílchez J, Infante J, Ramón C, Pelayo-Negro A, Illa I. Guía diagnóstica en el paciente con enfermedad de Charcot-Marie-Tooth. Neurologia 2012; 27:169-78. [DOI: 10.1016/j.nrl.2011.04.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 04/14/2011] [Indexed: 01/31/2023] Open
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Berciano J, Sevilla T, Casasnovas C, Sivera R, Vílchez J, Infante J, Ramón C, Pelayo-Negro A, Illa I. Guidelines for molecular diagnosis of Charcot-Marie-Tooth disease. NEUROLOGÍA (ENGLISH EDITION) 2012. [DOI: 10.1016/j.nrleng.2012.04.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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Liu S, Sawada T, Lee S, Yu W, Silverio G, Alapatt P, Millan I, Shen A, Saxton W, Kanao T, Takahashi R, Hattori N, Imai Y, Lu B. Parkinson's disease-associated kinase PINK1 regulates Miro protein level and axonal transport of mitochondria. PLoS Genet 2012; 8:e1002537. [PMID: 22396657 PMCID: PMC3291531 DOI: 10.1371/journal.pgen.1002537] [Citation(s) in RCA: 293] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Accepted: 12/29/2011] [Indexed: 11/18/2022] Open
Abstract
Mutations in Pten-induced kinase 1 (PINK1) are linked to early-onset familial Parkinson's disease (FPD). PINK1 has previously been implicated in mitochondrial fission/fusion dynamics, quality control, and electron transport chain function. However, it is not clear how these processes are interconnected and whether they are sufficient to explain all aspects of PINK1 pathogenesis. Here we show that PINK1 also controls mitochondrial motility. In Drosophila, downregulation of dMiro or other components of the mitochondrial transport machinery rescued dPINK1 mutant phenotypes in the muscle and dopaminergic (DA) neurons, whereas dMiro overexpression alone caused DA neuron loss. dMiro protein level was increased in dPINK1 mutant but decreased in dPINK1 or dParkin overexpression conditions. In Drosophila larval motor neurons, overexpression of dPINK1 inhibited axonal mitochondria transport in both anterograde and retrograde directions, whereas dPINK1 knockdown promoted anterograde transport. In HeLa cells, overexpressed hPINK1 worked together with hParkin, another FPD gene, to regulate the ubiquitination and degradation of hMiro1 and hMiro2, apparently in a Ser-156 phosphorylation-independent manner. Also in HeLa cells, loss of hMiro promoted the perinuclear clustering of mitochondria and facilitated autophagy of damaged mitochondria, effects previously associated with activation of the PINK1/Parkin pathway. These newly identified functions of PINK1/Parkin and Miro in mitochondrial transport and mitophagy contribute to our understanding of the complex interplays in mitochondrial quality control that are critically involved in PD pathogenesis, and they may explain the peripheral neuropathy symptoms seen in some PD patients carrying particular PINK1 or Parkin mutations. Moreover, the different effects of loss of PINK1 function on Miro protein level in Drosophila and mouse cells may offer one explanation of the distinct phenotypic manifestations of PINK1 mutants in these two species. Parkinson's disease (PD) is the second most common neurodegenerative disease. It mainly affects movement in elderly people and was traditionally considered a sporadic disease with no known cause. Discoveries of genes associated with familial PD (FPD) have demonstrated that PD pathogenesis can be significantly influenced by an individual's genetic makeup. Understanding the functions of these FPD genes will allow better understanding of the sporadic PD cases. PINK1 and Parkin are genes associated with FPD that affect patients at an early age. Mutations in PINK1 and Parkin lead to the accumulation of damaged mitochondria, the powerhouse of the cell, as a result of impairments of the mitochondrial quality control system. However, the mechanism of PINK1/Parkin action remains poorly understood. Here we show that PINK1 and Parkin act together to regulate Miro, a key component of the mitochondrial transport machinery, and that altered activities of PINK1 cause aberrant mitochondrial transport. Regulation of mitochondrial transport may be a critical aspect of the mechanisms by which the PINK1/Parkin pathway governs mitochondrial quality control. Dysfunction of this process could contribute to the loss of DA neurons, the cardinal feature of PD, as well as the peripheral neuropathy symptom associated with particular PINK1 or Parkin mutations.
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Affiliation(s)
- Song Liu
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Tomoyo Sawada
- Department of Neurology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- CREST (Core Research for Evolutionary Science and Technology), Japan Science and Technology Agency, Saitama, Japan
| | - Seongsoo Lee
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Wendou Yu
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - George Silverio
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Philomena Alapatt
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Ivan Millan
- Neuroscience Program, Stanford University School of Medicine, Stanford, California, United States of America
| | - Alice Shen
- College of Arts and Sciences, Washington University, St. Louis, Missouri, United States of America
| | - William Saxton
- Department of Molecular, Cell, and Developmental Biology, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Tomoko Kanao
- Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Ryosuke Takahashi
- Department of Neurology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- CREST (Core Research for Evolutionary Science and Technology), Japan Science and Technology Agency, Saitama, Japan
| | - Nobutaka Hattori
- CREST (Core Research for Evolutionary Science and Technology), Japan Science and Technology Agency, Saitama, Japan
- Department of Neurology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yuzuru Imai
- Department of Neuroscience for Neurodegenerative Disorders, Juntendo University Graduate School of Medicine, Tokyo, Japan
- * E-mail: (YI); (BL)
| | - Bingwei Lu
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail: (YI); (BL)
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Abstract
Gene products such as organelles, proteins and RNAs are actively transported to synaptic terminals for the remodeling of pre-existing neuronal connections and formation of new ones. Proteins described as molecular motors mediate this transport and utilize specialized cytoskeletal proteins that function as molecular tracks for the motor based transport of cargos. Molecular motors such as kinesins and dynein's move along microtubule tracks formed by tubulins whereas myosin motors utilize tracks formed by actin. Deficits in active transport of gene products have been implicated in a number of neurological disorders. We describe such disorders collectively as "transportopathies". Here we review current knowledge of critical components of active transport and their relevance to neurodegenerative diseases.
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Yi L, Donsante A, Kennerson ML, Mercer JFB, Garbern JY, Kaler SG. Altered intracellular localization and valosin-containing protein (p97 VCP) interaction underlie ATP7A-related distal motor neuropathy. Hum Mol Genet 2011; 21:1794-807. [PMID: 22210628 DOI: 10.1093/hmg/ddr612] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
ATP7A is a P-type ATPase that regulates cellular copper homeostasis by activity at the trans-Golgi network (TGN) and plasma membrane (PM), with the location normally governed by intracellular copper concentration. Defects in ATP7A lead to Menkes disease or its milder variant, occipital horn syndrome or to a newly discovered condition, ATP7A-related distal motor neuropathy (DMN), for which the precise pathophysiology has been obscure. We investigated two ATP7A motor neuropathy mutations (T994I, P1386S) previously associated with abnormal intracellular trafficking. In the patients' fibroblasts, total internal reflection fluorescence microscopy indicated a shift in steady-state equilibrium of ATP7A(T994I) and ATP7A(P1386S), with exaggerated PM localization. Transfection of Hek293T cells and NSC-34 motor neurons with the mutant alleles tagged with the Venus fluorescent protein also revealed excess PM localization. Endocytic retrieval of the mutant alleles from the PM to the TGN was impaired. Immunoprecipitation assays revealed an abnormal interaction between ATP7A(T994I) and p97/VCP, an ubiquitin-selective chaperone which is mutated in two autosomal dominant forms of motor neuron disease: amyotrophic lateral sclerosis and inclusion body myopathy with early-onset Paget disease and fronto-temporal dementia. Small-interfering RNA (SiRNA) knockdown of p97/VCP corrected ATP7A(T994I) mislocalization. Flow cytometry documented that non-permeabilized ATP7A(P1386S) fibroblasts bound a carboxyl-terminal ATP7A antibody, consistent with relocation of the ATP7A di-leucine endocytic retrieval signal to the extracellular surface and partially destabilized insertion of the eighth transmembrane helix. Our findings illuminate the mechanisms underlying ATP7A-related DMN and establish a link between p97/VCP and genetically distinct forms of motor neuron degeneration.
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Affiliation(s)
- Ling Yi
- Unit on Human Copper Metabolism, Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892-1853, USA
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Cavalcanti F, Kidd T, Patitucci A, Valentino P, Bono F, Nisticò R, Quattrone A. An axon regeneration signature in a Charcot-Marie-Tooth disease type 2 patient. J Neurogenet 2011; 23:324-8. [PMID: 19657941 DOI: 10.1080/01677060802447585] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Charcot-Marie-Tooth disease (CMT) is one of the most common inherited peripheral neuropathies. The underlying mutations in demyelinating forms tend to affect genes expressed in Schwann cells (CMT types 1, 3, and 4), while axonal forms of the disease usually have their origins in genes expressed in the affected neurons (CMT type 2). Repeated rounds of nerve degeneration and regeneration characterize CMT2, but evidence for regeneration has not been demonstrated at a molecular level. Subtractive hybridization was performed on sural nerve biopsies from a patient presenting an axonal form of CMT and an unaffected sibling, which revealed an overexpression of genes associated with the regeneration of axons, including PMP22, SPARC/osteonectin, CD9, CD44, EEF1A1, and gamma-actin. These results suggest that axonal degeneration elicits a regeneration transcriptional response in the surrounding Schwann cells. This response contrasts with other neurodegenerative diseases, in which programmed cell death or an inappropriate immune response are activated. Additionally, Lamin A/C, which is mutated in CMT2B1, was overexpressed in the patient, suggesting that CMT-causing genes may interact in a regulatory network.
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Affiliation(s)
- Francesca Cavalcanti
- Institute of Neurological Sciences, National Research Council, Mangone, Cosenza, Italy
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d'Ydewalle C, Krishnan J, Chiheb DM, Van Damme P, Irobi J, Kozikowski AP, Vanden Berghe P, Timmerman V, Robberecht W, Van Den Bosch L. HDAC6 inhibitors reverse axonal loss in a mouse model of mutant HSPB1-induced Charcot-Marie-Tooth disease. Nat Med 2011; 17:968-74. [PMID: 21785432 DOI: 10.1038/nm.2396] [Citation(s) in RCA: 352] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 05/10/2011] [Indexed: 12/20/2022]
Abstract
Charcot-Marie-Tooth disease (CMT) is the most common inherited disorder of the peripheral nervous system. Mutations in the 27-kDa small heat-shock protein gene (HSPB1) cause axonal CMT or distal hereditary motor neuropathy (distal HMN). We developed and characterized transgenic mice expressing two different HSPB1 mutations (S135F and P182L) in neurons only. These mice showed all features of CMT or distal HMN dependent on the mutation. Expression of mutant HSPB1 decreased acetylated α-tubulin abundance and induced severe axonal transport deficits. An increase of α-tubulin acetylation induced by pharmacological inhibition of histone deacetylase 6 (HDAC6) corrected the axonal transport defects caused by HSPB1 mutations and rescued the CMT phenotype of symptomatic mutant HSPB1 mice. Our findings demonstrate the pathogenic role of α-tubulin deacetylation in mutant HSPB1-induced neuropathies and offer perspectives for using HDAC6 inhibitors as a therapeutic strategy for hereditary axonopathies.
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Yamauchi J, Torii T, Kusakawa S, Sanbe A, Nakamura K, Takashima S, Hamasaki H, Kawaguchi S, Miyamoto Y, Tanoue A. The mood stabilizer valproic acid improves defective neurite formation caused by Charcot-Marie-Tooth disease-associated mutant Rab7 through the JNK signaling pathway. J Neurosci Res 2011; 88:3189-97. [PMID: 20645406 DOI: 10.1002/jnr.22460] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Charcot-Marie-Tooth (CMT) disease is the most frequent peripheral neuropathy affecting the Schwann cells and neurons. CMT disease type 2 (CMT2) neuropathies are characterized by peripheral nerve aberrance. Four missense mutations of Rab7, a small GTPase of the Rab family involved in intracellular vesicular trafficking, are associated with the CMT2B phenotype. Despite a growing body of evidence concerning the gene structures responsible for genetically heterogenous CMT2B and other CMT2 neuropathies, little is known about the in vitro neuropathy model and how CMT2B-associated mutation-caused aberrant neuritogenesis is properly reversed. Here, we show that valproic acid (VPA), a classical mood-stabilizing drug, improves defective neurite formation in N1E-115 neuroblastoma cells regardless of which CMT2B-associated Rab7 mutant protein is expressed. The effect is mediated by c-Jun N-terminal kinase (JNK) signaling, but not by deacetylase inhibition activity of VPA itself. Furthermore, VPA has similar effects in dorsal root ganglion (DRG) neurons expressing any of the four mutant Rab7 proteins. Thus, VPA has a previously unknown potential to improve defective neuritogenesis associated with CMT2B in vitro, indicating that JNK should be a potential therapeutic target for treatments aimed at improving neuritogenesis.
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Affiliation(s)
- Junji Yamauchi
- Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo, Japan.
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Yu-Wai-Man P, Griffiths PG, Chinnery PF. Mitochondrial optic neuropathies - disease mechanisms and therapeutic strategies. Prog Retin Eye Res 2011; 30:81-114. [PMID: 21112411 PMCID: PMC3081075 DOI: 10.1016/j.preteyeres.2010.11.002] [Citation(s) in RCA: 431] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leber hereditary optic neuropathy (LHON) and autosomal-dominant optic atrophy (DOA) are the two most common inherited optic neuropathies in the general population. Both disorders share striking pathological similarities, marked by the selective loss of retinal ganglion cells (RGCs) and the early involvement of the papillomacular bundle. Three mitochondrial DNA (mtDNA) point mutations; m.3460G>A, m.11778G>A, and m.14484T>C account for over 90% of LHON cases, and in DOA, the majority of affected families harbour mutations in the OPA1 gene, which codes for a mitochondrial inner membrane protein. Optic nerve degeneration in LHON and DOA is therefore due to disturbed mitochondrial function and a predominantly complex I respiratory chain defect has been identified using both in vitro and in vivo biochemical assays. However, the trigger for RGC loss is much more complex than a simple bioenergetic crisis and other important disease mechanisms have emerged relating to mitochondrial network dynamics, mtDNA maintenance, axonal transport, and the involvement of the cytoskeleton in maintaining a differential mitochondrial gradient at sites such as the lamina cribosa. The downstream consequences of these mitochondrial disturbances are likely to be influenced by the local cellular milieu. The vulnerability of RGCs in LHON and DOA could derive not only from tissue-specific, genetically-determined biological factors, but also from an increased susceptibility to exogenous influences such as light exposure, smoking, and pharmacological agents with putative mitochondrial toxic effects. Our concept of inherited mitochondrial optic neuropathies has evolved over the past decade, with the observation that patients with LHON and DOA can manifest a much broader phenotypic spectrum than pure optic nerve involvement. Interestingly, these phenotypes are sometimes clinically indistinguishable from other neurodegenerative disorders such as Charcot-Marie-Tooth disease, hereditary spastic paraplegia, and multiple sclerosis, where mitochondrial dysfunction is also thought to be an important pathophysiological player. A number of vertebrate and invertebrate disease models has recently been established to circumvent the lack of human tissues, and these have already provided considerable insight by allowing direct RGC experimentation. The ultimate goal is to translate these research advances into clinical practice and new treatment strategies are currently being investigated to improve the visual prognosis for patients with mitochondrial optic neuropathies.
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MESH Headings
- Animals
- DNA, Mitochondrial/genetics
- Disease Models, Animal
- Humans
- Optic Atrophy, Autosomal Dominant/pathology
- Optic Atrophy, Autosomal Dominant/physiopathology
- Optic Atrophy, Autosomal Dominant/therapy
- Optic Atrophy, Hereditary, Leber/pathology
- Optic Atrophy, Hereditary, Leber/physiopathology
- Optic Atrophy, Hereditary, Leber/therapy
- Optic Nerve/pathology
- Phenotype
- Point Mutation
- Retinal Ganglion Cells/pathology
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Affiliation(s)
- Patrick Yu-Wai-Man
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, UK.
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Abe A, Numakura C, Kijima K, Hayashi M, Hashimoto T, Hayasaka K. Molecular diagnosis and clinical onset of Charcot–Marie–Tooth disease in Japan. J Hum Genet 2011; 56:364-8. [DOI: 10.1038/jhg.2011.20] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Cacace AT, Pinheiro JMB. The mitochondrial connection in auditory neuropathy. Audiol Neurootol 2011; 16:398-413. [PMID: 21266802 DOI: 10.1159/000323276] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Accepted: 11/30/2010] [Indexed: 12/21/2022] Open
Abstract
'Auditory neuropathy' (AN), the term used to codify a primary degeneration of the auditory nerve, can be linked directly or indirectly to mitochondrial dysfunction. These observations are based on the expression of AN in known mitochondrial-based neurological diseases (Friedreich's ataxia, Mohr-Tranebjærg syndrome), in conditions where defects in axonal transport, protein trafficking, and fusion processes perturb and/or disrupt mitochondrial dynamics (Charcot-Marie-Tooth disease, autosomal dominant optic atrophy), in a common neonatal condition known to be toxic to mitochondria (hyperbilirubinemia), and where respiratory chain deficiencies produce reductions in oxidative phosphorylation that adversely affect peripheral auditory mechanisms. This body of evidence is solidified by data derived from temporal bone and genetic studies, biochemical, molecular biologic, behavioral, electroacoustic, and electrophysiological investigations.
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Affiliation(s)
- Anthony T Cacace
- Department of Communication Sciences and Disorders, Wayne State University, Detroit, Mich 48202, USA. cacacea @ wayne.edu
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BasuRay S, Mukherjee S, Romero E, Wilson MC, Wandinger-Ness A. Rab7 mutants associated with Charcot-Marie-Tooth disease exhibit enhanced NGF-stimulated signaling. PLoS One 2010; 5:e15351. [PMID: 21151572 PMCID: PMC3000344 DOI: 10.1371/journal.pone.0015351] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 11/11/2010] [Indexed: 11/30/2022] Open
Abstract
Missense mutants in the late endosomal Rab7 GTPase cause the autosomal dominant peripheral neuropathy Charcot-Marie-Tooth disease type 2B (CMT2B). As yet, the pathological mechanisms connecting mutant Rab7 protein expression to altered neuronal function are undefined. Here, we analyze the effects Rab7 CMT2B mutants on nerve growth factor (NGF) dependent intracellular signaling in PC12 cells. The nerve growth factor receptor TrkA interacted similarly with Rab7 wild-type and CMT2B mutant proteins, but the mutant proteins significantly enhanced TrkA phosphorylation in response to brief NGF stimulation. Two downstream signaling pathways (Erk1/2 and Akt) that are directly activated in response to phospho-TrkA were differentially affected. Akt signaling, arising in response to activated TrkA at the plasma membrane was unaffected. However Erk1/2 phosphorylation, triggered on signaling endosomes, was increased. Cytoplasmic phospho-Erk1/2 persisted at elevated levels relative to control samples for up to 24 h following NGF stimulation. Nuclear shuttling of phospho Erk1/2, which is required to induce MAPK phosphatase expression and down regulate signaling, was greatly reduced by the Rab7 CMT2B mutants and explains the previously reported inhibition in PC12 neurite outgrowth. In conclusion, the data demonstrate a mechanistic link between Rab7 CMT2B mutants and altered TrkA and Erk1/2 signaling from endosomes.
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Affiliation(s)
- Soumik BasuRay
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States of America
| | - Sanchita Mukherjee
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States of America
| | - Elsa Romero
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States of America
| | - Michael C. Wilson
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States of America
| | - Angela Wandinger-Ness
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States of America
- * E-mail:
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50
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CMT2B-associated Rab7 mutants inhibit neurite outgrowth. Acta Neuropathol 2010; 120:491-501. [PMID: 20464402 DOI: 10.1007/s00401-010-0696-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 05/04/2010] [Accepted: 05/05/2010] [Indexed: 12/11/2022]
Abstract
Charco-Marie-Tooth type 2B (CMT2B) neuropathy is a rare autosomal-dominant axonal disorder characterized by distal weakness, muscle atrophy, and prominent sensory loss often complicated by foot ulcerations. CMT2B is associated with mutations of the Rab7 protein, a small GTPase controlling late endocytic traffic. Currently, it is still unknown how these mutations cause the neuropathy. Indeed, CMT2B selectively affects neuronal processes, despite the ubiquitous expression of Rab7. Therefore, this study focused on whether these disorder-associated mutations exert an effect on neurite outgrowth. We observed a marked inhibition of neurite outgrowth upon expression of all the CMT2B-associated mutants in the PC12 and Neuro2A cell lines. Thus, our data strongly support previous genetic data which proposed that these Rab7 mutations are indeed causally related to CMT2B. Inhibition of neurite outgrowth by these CMT2B-associated Rab7 mutants was confirmed biochemically by impaired up-regulation of growth-associated protein 43 (GAP43) in PC12 cells and of the nuclear neuronal differentiation marker NeuN in Neuro2A cells. Expression of a constitutively active Rab7 mutant had a similar effect to the expression of the CMT2B-associated Rab7 mutants. The active behavior of these CMT2B-associated mutants is in line with their previously demonstrated increased GTP loading, thus confirming that active Rab7 mutants are responsible for CMT2B. Our findings provide an explanation for the ability of CMT2B-associated Rab7 mutants to override the activity of wild-type Rab7 in heterozygous patients. Thus, our data suggest that lowering the activity of Rab7 in neurons could be a targeted therapy for CMT2B.
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