1
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Lorenzoni PJ, Bayer DL, Ducci RDP, Fustes OJH, do Vale Pascoal Rodrigues PR, Werneck LC, Kay CSK, Scola RH. Spectrum of SPTLC1-related disorders: a novel case of 'Ser331 syndrome' that expand the phenotype of hereditary sensory and autonomic neuropathy type 1A and motor neuron diseases. Neurol Sci 2023:10.1007/s10072-023-06763-3. [PMID: 36964315 DOI: 10.1007/s10072-023-06763-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 03/16/2023] [Indexed: 03/26/2023]
Abstract
We report a patient with early-onset hereditary sensory and autonomic neuropathy type 1A (HSAN-1A) who developed a distinct phenotype, with tongue fasciculation and atrophy, due to a mutation at serine 331 in the SPTLC1 gene. HSAN-1A manifestation causing tongue fasciculation and atrophy have been rarely found. Our report adds to the growing evidence of the existence of an overlap between hereditary neuropathy and motor neuron disease caused by pathogenic p.S331Y variant in SPTLC1 gene.
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Affiliation(s)
- Paulo José Lorenzoni
- Service of Neuromuscular Disorders, Division of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal Do Paraná (UFPR), Curitiba, 80060-900, Brazil.
| | - Dafne Luana Bayer
- Service of Neuromuscular Disorders, Division of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal Do Paraná (UFPR), Curitiba, 80060-900, Brazil
| | - Renata Dal-Prá Ducci
- Service of Neuromuscular Disorders, Division of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal Do Paraná (UFPR), Curitiba, 80060-900, Brazil
| | - Otto Jesus Hernandez Fustes
- Service of Neuromuscular Disorders, Division of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal Do Paraná (UFPR), Curitiba, 80060-900, Brazil
| | - Paula Raquel do Vale Pascoal Rodrigues
- Service of Neuromuscular Disorders, Division of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal Do Paraná (UFPR), Curitiba, 80060-900, Brazil
| | - Lineu Cesar Werneck
- Service of Neuromuscular Disorders, Division of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal Do Paraná (UFPR), Curitiba, 80060-900, Brazil
| | - Cláudia Suemi Kamoi Kay
- Service of Neuromuscular Disorders, Division of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal Do Paraná (UFPR), Curitiba, 80060-900, Brazil
| | - Rosana Herminia Scola
- Service of Neuromuscular Disorders, Division of Neurology, Department of Internal Medicine, Hospital de Clínicas, Universidade Federal Do Paraná (UFPR), Curitiba, 80060-900, Brazil
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2
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Lischka A, Lassuthova P, Çakar A, Record CJ, Van Lent J, Baets J, Dohrn MF, Senderek J, Lampert A, Bennett DL, Wood JN, Timmerman V, Hornemann T, Auer-Grumbach M, Parman Y, Hübner CA, Elbracht M, Eggermann K, Geoffrey Woods C, Cox JJ, Reilly MM, Kurth I. Genetic pain loss disorders. Nat Rev Dis Primers 2022; 8:41. [PMID: 35710757 DOI: 10.1038/s41572-022-00365-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/10/2022] [Indexed: 01/05/2023]
Abstract
Genetic pain loss includes congenital insensitivity to pain (CIP), hereditary sensory neuropathies and, if autonomic nerves are involved, hereditary sensory and autonomic neuropathy (HSAN). This heterogeneous group of disorders highlights the essential role of nociception in protecting against tissue damage. Patients with genetic pain loss have recurrent injuries, burns and poorly healing wounds as disease hallmarks. CIP and HSAN are caused by pathogenic genetic variants in >20 genes that lead to developmental defects, neurodegeneration or altered neuronal excitability of peripheral damage-sensing neurons. These genetic variants lead to hyperactivity of sodium channels, disturbed haem metabolism, altered clathrin-mediated transport and impaired gene regulatory mechanisms affecting epigenetic marks, long non-coding RNAs and repetitive elements. Therapies for pain loss disorders are mainly symptomatic but the first targeted therapies are being tested. Conversely, chronic pain remains one of the greatest unresolved medical challenges, and the genes and mechanisms associated with pain loss offer new targets for analgesics. Given the progress that has been made, the coming years are promising both in terms of targeted treatments for pain loss disorders and the development of innovative pain medicines based on knowledge of these genetic diseases.
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Affiliation(s)
- Annette Lischka
- Institute of Human Genetics, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Petra Lassuthova
- Department of Paediatric Neurology, 2nd Faculty of Medicine, Charles University in Prague and Motol University Hospital, Prague, Czech Republic
| | - Arman Çakar
- Neuromuscular Unit, Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Christopher J Record
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Jonas Van Lent
- Peripheral Neuropathy Research Group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born Bunge, Antwerp, Belgium
| | - Jonathan Baets
- Laboratory of Neuromuscular Pathology, Institute Born Bunge, Antwerp, Belgium.,Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Antwerp, Belgium
| | - Maike F Dohrn
- Department of Neurology, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany.,Dr. John T. Macdonald Foundation, Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Jan Senderek
- Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians-University, Munich, Germany
| | - Angelika Lampert
- Institute of Physiology, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany
| | - David L Bennett
- Nuffield Department of Clinical Neuroscience, Oxford University, Oxford, UK
| | - John N Wood
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London, UK
| | - Vincent Timmerman
- Peripheral Neuropathy Research Group, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born Bunge, Antwerp, Belgium
| | - Thorsten Hornemann
- Department of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Michaela Auer-Grumbach
- Department of Orthopedics and Trauma Surgery, Medical University of Vienna, Vienna, Austria
| | - Yesim Parman
- Neuromuscular Unit, Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | | | - Miriam Elbracht
- Institute of Human Genetics, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Katja Eggermann
- Institute of Human Genetics, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany
| | - C Geoffrey Woods
- Cambridge Institute for Medical Research, Keith Peters Building, Cambridge Biomedical Campus, Cambridge, UK
| | - James J Cox
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London, UK
| | - Mary M Reilly
- Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Ingo Kurth
- Institute of Human Genetics, Medical Faculty, Uniklinik RWTH Aachen University, Aachen, Germany.
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3
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Motley W, Chaudry V, Lloyd TE. Treatment and Management of Hereditary Neuropathies. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00014-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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4
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Loh J, Cyr K, Martin R. Ankle Fracture in Hereditary Sensory Neuropathy Type 1. J Foot Ankle Surg 2021; 60:621-625. [PMID: 33509718 PMCID: PMC7538394 DOI: 10.1053/j.jfas.2020.09.015] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 09/30/2020] [Indexed: 02/03/2023]
Abstract
Ankle fractures account for approximately 9% of all adult fractures annually. The ankle anatomically is particularly vulnerable to significant skin compromise in the setting of trauma. Significant fracture blistering and soft tissue compromise is predominantly seen in high-energy ankle injuries. Hereditary sensory autonomic neuropathy type I is a rare progressive neurological disorder resulting in distal sensory loss and autonomic disturbances with variable motor involvement. We present a case involving a hereditary sensory autonomic neuropathy type I patient with unexpected significant soft tissue injury on the background of a low energy ankle fracture. The aim was to outline the diagnosis and complex management considerations related to hereditary sensory neuropathic-associated ankle injuries.
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Affiliation(s)
- Jeremy Loh
- Resident, Orthopaedic Surgery Department, Eastern Heath, St. John's, NL, Canada,Address correspondence to: Jeremy Loh, MBBS, 1168 W.42nd Ave, Vancouver, BC V6M 2A8, Canada
| | - Kayla Cyr
- Resident, Orthopaedic Surgery Department, Eastern Heath, St. John's, NL, Canada
| | - Roderick Martin
- Clinical Associate Professor, Memorial University, St. Clare's Mercy Hospital, St. John's, NL, Canada
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5
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Li L, Jia C, Tang Y, Kong Y, Xia Y, Ma L. Novel Gross Deletion Mutations in NTRK1 Gene Associated With Congenital Insensitivity to Pain With Anhidrosis. Front Pediatr 2021; 9:638190. [PMID: 33748046 PMCID: PMC7969531 DOI: 10.3389/fped.2021.638190] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 01/20/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Congenital insensitivity to pain with anhidrosis (CIPA) is a rare inherited autosomal recessive disorder characterized by insensitivity to noxious stimuli, anhidrosis, recurrent fever, and intellectual disability. CIPA is mainly caused by mutations in the neurotrophic tyrosine kinase receptor type 1 gene (NTRK1). This study aims to identify pathogenic mutations underlying CIPA in two unrelated Chinese families. Methods: DNA was extracted from blood samples of patients and their available family members and subjected to whole exome sequencing (WES). Real-time PCR (qPCR), Gap-PCR, and Sanger sequencing were applied to verify the identified variants. Result: We found novel compound gross deletion mutations [exon1-6 del (g.1-1258_10169del); exon5-7 del (g.6995_11999del)] of NTRK1 (MIM 191315) gene in family 1 and the compound heterozygous mutations [c.851-33T>A; exon5-7 del (g.6995_11999del)] in family 2. Interestingly, we discovered the intragenic novel gross deletion [exon5-7 del (g.6995_11999del)] mediated by recombination between Alu elements. Conclusions: The present study highlights two rare gross deletion mutations in the NTRK1 gene associated with CIPA in two unrelated Chinese families. The deletion of exon1-6 (g.1-1258_10169del) is thought to be the largest NTRK1 deletion reported to date. Our findings expand the mutation spectrum of NTRK1 mutations in the Chinese and could be useful for prenatal interventions and more precise pharmacological treatments to patients. WES conducted in our study is a convenient and useful tool for clinical diagnosis of CIPA and other associated disorders.
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Affiliation(s)
- Lulu Li
- Department of Newborn Screening Center, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing Maternal and Child Health Care Hospital, Beijing, China
| | - Chao Jia
- Department of Neonatology, Hebei Provincial Children's Hospital, Shijiazhuang, China
| | - Yue Tang
- Department of Newborn Screening Center, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing Maternal and Child Health Care Hospital, Beijing, China
| | - Yuanyuan Kong
- Department of Newborn Screening Center, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing Maternal and Child Health Care Hospital, Beijing, China
| | - Yaofang Xia
- Department of Neonatology, Hebei Provincial Children's Hospital, Shijiazhuang, China
| | - Li Ma
- Department of Neonatology, Hebei Provincial Children's Hospital, Shijiazhuang, China
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6
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Kaur D, Tiwana H, Stino A, Sandroni P. Autonomic neuropathies. Muscle Nerve 2020; 63:10-21. [PMID: 32926436 DOI: 10.1002/mus.27048] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 08/07/2020] [Accepted: 08/11/2020] [Indexed: 12/17/2022]
Abstract
Autonomic neuropathies represent a complex group of disorders that preferentially target autonomic fibers and can be classified as either acute/subacute or chronic in onset. Acute-onset autonomic neuropathies manifest with such conditions as paraneoplastic syndromes, Guillain-Barre syndrome, Sjögren syndrome, infection, or toxins/chemotherapy. When the presentation is acute, immune-mediated, and without a secondary cause, autoimmune autonomic ganglionopathy is likely, and should be considered for immunotherapy. Of the chronic-onset forms, diabetes is the most widespread and disabling, with autonomic impairment portending increased mortality and cardiac wall remodeling risk. Acquired light chain (AL) and transthyretin (TTR) amyloidosis represent two other key etiologies, with TTR amyloidosis now amenable to newly-approved gene-modifying therapies. The COMPASS-31 questionnaire is a validated outcome measure that can be used to monitor autonomic severity and track treatment response. Symptomatic treatments targeting orthostatic hypotension, among other symptoms, should be individualized and complement disease-modifying therapy, when possible.
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Affiliation(s)
- Divpreet Kaur
- Department of Neurology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Harmanpreet Tiwana
- Department of Neurology, Dartmouth-Hitchcok Medical Center, Lebanon, New Hampshire, USA
| | - Amro Stino
- Department of Neurology, Division of Neuromuscular Medicine, University of Michigan School of Medicine, Ann Arbor, Michigan, USA
| | - Paola Sandroni
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
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7
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Abstract
Long chain base (LCB) is a unique building block found in sphingolipids. The initial step of LCB biosynthesis stems from serine:palmitoyl-CoA transferase enzyme, producing 3-ketodihydrosphingosine with multiple regulatory proteins including small subunit SPT a/b and orosomucoid-like protein1-3. 3-Ketodihydrosphingosine reductase and sphingolipid Δ4-desaturase, both of them poorly characterized mammalian enzymes, play key roles for neurological homeostasis based on their pathogenic mutation in humans. Ceramide synthase in mammals has six isoforms with distinct phenotype in each knockout mouse. In plants and fungi, sphingolipids also contain phytosphingosine due to sphingolipid C4-hydroxylase. In contrast to previous notion that dietary intake might be its major route in animals, emerging evidences suggested that phytosphingosine biosynthesis does occur in some tissues such as the skin by mammalian C4-hydroxylase activity of the DEGS2 gene. This short review summarizes LCB biosynthesis with their associating metabolic pathways in animals, plants and fungi. Sphingolipid is a group of lipids that contains a unique building block known as long chain base (LCB). LCB is susceptible to various biosynthetic reactions such as unsaturation, hydroxylation and methylation. A failure of these enzymatic reactions leads to the pathogenesis in humans with an elevation of LCB-derived specific biomarkers. Herein, we summarized emerging evidences in mammalian LCB biosynthesis in sphingolipids. Some unique metabolic pathways in plants and fungi were also discussed.
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8
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Haribowo AG, Hannich JT, Michel AH, Megyeri M, Schuldiner M, Kornmann B, Riezman H. Cytotoxicity of 1-deoxysphingolipid unraveled by genome-wide genetic screens and lipidomics in Saccharomyces cerevisiae. Mol Biol Cell 2019; 30:2814-2826. [PMID: 31509475 PMCID: PMC6789163 DOI: 10.1091/mbc.e19-07-0364] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Hereditary sensory and autonomic neuropathy (HSAN) types IA and IC (IA/C) are caused by elevated levels of an atypical class of lipid named 1-deoxysphingolipid (DoxSL). How elevated levels of DoxSL perturb the physiology of the cell and how the perturbations lead to HSAN IA/C are largely unknown. In this study, we show that C26-1-deoxydihydroceramide (C26-DoxDHCer) is highly toxic to the cell, while C16- and C18-DoxDHCer are less toxic. Genome-wide genetic screens and lipidomics revealed the dynamics of DoxSL accumulation and DoxSL species responsible for the toxicity over the course of DoxSL accumulation. Moreover, we show that disruption of F-actin organization, alteration of mitochondrial shape, and accumulation of hydrophobic bodies by DoxSL are not sufficient to cause complete cellular failure. We found that cell death coincides with collapsed ER membrane, although we cannot rule out other possible causes of cell death. Thus, we have unraveled key principles of DoxSL cytotoxicity that may help to explain the clinical features of HSAN IA/C.
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Affiliation(s)
- A Galih Haribowo
- NCCR Chemical Biology and Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland
| | - J Thomas Hannich
- NCCR Chemical Biology and Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland
| | - Agnès H Michel
- Department of Biochemistry, University of Oxford, OX1 3QU Oxford, United Kingdom
| | - Márton Megyeri
- Department of Molecular Genetics, Weizmann Institute of Science, 76100 Rehovot, Israel.,Department of Biomolecular Sciences, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Benoît Kornmann
- Department of Biochemistry, University of Oxford, OX1 3QU Oxford, United Kingdom
| | - Howard Riezman
- NCCR Chemical Biology and Department of Biochemistry, University of Geneva, 1211 Geneva, Switzerland
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9
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Abstract
PURPOSE OF REVIEW Hereditary sensory and autonomic neuropathies (HSANs) are a clinically heterogeneous group of inherited neuropathies featuring prominent sensory and autonomic involvement. Classification of HSAN is based on mode of inheritance, genetic mutation, and phenotype. In this review, we discuss the recent additions to this classification and the important updates on management with a special focus on the recently investigated disease-modifying agents. RECENT FINDINGS In this past decade, three more HSAN types were added to the classification creating even more diversity in the genotype-phenotype. Clinical trials are underway for disease-modifying and symptomatic therapeutics, targeting mainly HSAN type III. Obtaining genetic testing leads to accurate diagnosis and guides focused management in the setting of such a diverse and continuously growing phenotype. It also increases the wealth of knowledge on HSAN pathophysiologies which paves the way toward development of targeted genetic treatments in the era of precision medicine.
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10
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Canine neuropathies: powerful spontaneous models for human hereditary sensory neuropathies. Hum Genet 2019; 138:455-466. [PMID: 30955094 DOI: 10.1007/s00439-019-02003-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 03/18/2019] [Indexed: 12/16/2022]
Abstract
In humans, hereditary sensory neuropathies (HSN), also known as hereditary sensory and autonomic neuropathies (HSAN), constitute a clinically and genetically heterogeneous group of disorders characterized by progressive sensory loss, often accompanied by chronic skin ulcerations and nail dystrophic changes. To date, although around 20 genes have already been discovered, they do not explain the genetic causes of all patients. In dogs, similar neuropathies are also diagnosed, several breeds being predisposed to specific forms of the disease. Indeed, the breed specificity of most canine genetic diseases is due to the small numbers of founders and high levels of inbreeding. Recent knowledge and tools developed to study the canine genome efficiently allows deciphering the genetic bases of such diseases. To date, a dozen breeds are recognized to develop specific HSN. For the Border collie and hunting dog breeds, the genes involved have recently been discovered. Other affected breeds thus constitute potential genetic models, with new genes to be found in dogs that can be considered as candidate genes for human HSAN/HSN. Here, we review the different forms of human and canine HSAN/HSN and we present a novel form in Fox terrier cases, highlighting the advantages of the dog model for such rare human diseases.
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11
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Lone MA, Santos T, Alecu I, Silva LC, Hornemann T. 1-Deoxysphingolipids. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:512-521. [PMID: 30625374 DOI: 10.1016/j.bbalip.2018.12.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 12/14/2022]
Abstract
Sphingolipids (SLs) are fundamental components of eukaryotic cells. 1-Deoxysphingolipids differ structurally from canonical SLs as they lack the essential C1-OH group. Consequently, 1-deoxysphingolipids cannot be converted to complex sphingolipids and are not degraded over the canonical catabolic pathways. Pathologically elevated 1-deoxySLs are involved in several disease conditions. Within this review, we will provide an up-to-date overview on the metabolic, physiological and pathophysiological aspects of this enigmatic class of "headless" sphingolipids.
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Affiliation(s)
- M A Lone
- Institute for Clinical Chemistry, University Hospital Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland
| | - T Santos
- Institute for Clinical Chemistry, University Hospital Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland; iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - I Alecu
- Neural Regeneration Laboratory, India Taylor Lipidomic Research Platform, Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, Ottawa Brain and Mind Research Institute, University of Ottawa, Canada
| | - L C Silva
- iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - T Hornemann
- Institute for Clinical Chemistry, University Hospital Zurich, Switzerland; Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Switzerland.
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12
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Goins L, Spassieva S. Sphingoid bases and their involvement in neurodegenerative diseases. Adv Biol Regul 2018; 70:65-73. [PMID: 30377075 DOI: 10.1016/j.jbior.2018.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 10/22/2018] [Accepted: 10/23/2018] [Indexed: 06/08/2023]
Abstract
Sphingoid bases (also known as long-chain bases) form the backbone of sphingolipids. Sphingolipids comprise a large group of lipid molecules, which function as the building blocks of biological membranes and play important signaling and regulatory roles within cells. The roles of sphingoid bases in neurotoxicity and neurodegeneration have yet to be fully elucidated, as they are complex and multi-faceted. This comprises a new frontier of research that may provide us with important clues regarding their involvement in neurological health and disease. This paper explores various neurological diseases and conditions which result when the metabolism of sphingoid bases and some of their derivatives, such as sphingosine-1-phosphate and psychosine, becomes compromised due to the inhibition or mutation of key enzymes. Dysregulation of sphingoid base metabolism very often manifests with neurological symptoms, as sphingolipids are highly enriched in the nervous system, where they play important signaling and regulatory roles.
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Affiliation(s)
- Laura Goins
- Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Stefka Spassieva
- Department of Physiology, University of Kentucky, Lexington, KY, USA.
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13
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Caractérisation électroclinique des patients présentant une neuropathie sensitive associée à une toux chronique et un reflux gastro-œsophagien : cohorte Bordelaise. Neurophysiol Clin 2018. [DOI: 10.1016/j.neucli.2018.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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14
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Abstract
The human chaperonin TRiC consists of eight non-identical subunits, and its protein-folding activity is critical for cellular health. Misfolded proteins are associated with many human diseases, such as amyloid diseases, cancer, and neuropathies, making TRiC a potential therapeutic target. A detailed structural understanding of its ATP-dependent folding mechanism and substrate recognition is therefore of great importance. Of particular health-related interest is the mutation Histidine 147 to Arginine (H147R) in human TRiC subunit 5 (CCT5), which has been associated with hereditary sensory neuropathy. In this paper, we describe the crystal structures of CCT5 and the CCT5-H147R mutant, which provide important structural information for this vital protein-folding machine in humans. This first X-ray crystallographic study of a single human CCT subunit in the context of a hexadecameric complex can be expanded in the future to the other 7 subunits that form the TRiC complex.
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15
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Plassais J, Lagoutte L, Correard S, Paradis M, Guaguère E, Hédan B, Pommier A, Botherel N, Cadiergues MC, Pilorge P, Silversides D, Bizot M, Samuels M, Arnan C, Johnson R, Hitte C, Salbert G, Méreau A, Quignon P, Derrien T, André C. A Point Mutation in a lincRNA Upstream of GDNF Is Associated to a Canine Insensitivity to Pain: A Spontaneous Model for Human Sensory Neuropathies. PLoS Genet 2016; 12:e1006482. [PMID: 28033318 PMCID: PMC5198995 DOI: 10.1371/journal.pgen.1006482] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 11/15/2016] [Indexed: 01/06/2023] Open
Abstract
Human Hereditary Sensory Autonomic Neuropathies (HSANs) are characterized by insensitivity to pain, sometimes combined with self-mutilation. Strikingly, several sporting dog breeds are particularly affected by such neuropathies. Clinical signs appear in young puppies and consist of acral analgesia, with or without sudden intense licking, biting and severe self-mutilation of the feet, whereas proprioception, motor abilities and spinal reflexes remain intact. Through a Genome Wide Association Study (GWAS) with 24 affected and 30 unaffected sporting dogs using the Canine HD 170K SNP array (Illumina), we identified a 1.8 Mb homozygous locus on canine chromosome 4 (adj. p-val = 2.5x10-6). Targeted high-throughput sequencing of this locus in 4 affected and 4 unaffected dogs identified 478 variants. Only one variant perfectly segregated with the expected recessive inheritance in 300 sporting dogs of known clinical status, while it was never present in 900 unaffected dogs from 130 other breeds. This variant, located 90 kb upstream of the GDNF gene, a highly relevant neurotrophic factor candidate gene, lies in a long intergenic non-coding RNAs (lincRNA), GDNF-AS. Using human comparative genomic analysis, we observed that the canine variant maps onto an enhancer element. Quantitative RT-PCR of dorsal root ganglia RNAs of affected dogs showed a significant decrease of both GDNF mRNA and GDNF-AS expression levels (respectively 60% and 80%), as compared to unaffected dogs. We thus performed gel shift assays (EMSA) that reveal that the canine variant significantly alters the binding of regulatory elements. Altogether, these results allowed the identification in dogs of GDNF as a relevant candidate for human HSAN and insensitivity to pain, but also shed light on the regulation of GDNF transcription. Finally, such results allow proposing these sporting dog breeds as natural models for clinical trials with a double benefit for human and veterinary medicine. In this study, we present a canine neuropathy characterized by insensitivity to pain in the feet, sometimes combined with self-mutilation described in four sporting breeds. This particular phenotype has the clinical hallmarks of human Hereditary Sensory Autonomic Neuropathies (HSAN). As we hypothesized that a monogenic recessive disorder was shared between these breeds, we performed a Genome Wide Association Study (GWAS) to search for the genetic causes and found one homozygous chromosomal region in affected dogs. High-throughput sequencing of this region allowed the identification of a point mutation upstream to the GDNF gene and located in the last exon of a long non-coding RNA, GDNF-AS. We confirmed the perfect association of this variant with the disease using more than 900 unaffected dogs that do not present with this mutation. Functional analyses (qRT-PCR, EMSA) confirmed that the mutation alters the binding of regulatory complex, leading to a significant decrease of both GDNF and GDNF-AS mRNA expression levels. This work in canine spontaneous forms of human neuropathies allowed the identification of a novel gene GDNF and its regulation mechanism, not yet described in human HSAN, opening the field of clinical trials to benefit both canine and human medicine.
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Affiliation(s)
- Jocelyn Plassais
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
- * E-mail: (CA); (JP)
| | - Laetitia Lagoutte
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | - Solenne Correard
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | - Manon Paradis
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, University of Montreal, Montreal, Québec, Canada
| | | | - Benoit Hédan
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | - Alix Pommier
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | - Nadine Botherel
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | | | | | - David Silversides
- Department of Clinical Sciences, Faculté de Médecine Vétérinaire, University of Montreal, Montreal, Québec, Canada
| | - Maud Bizot
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | - Mark Samuels
- Department of Biochemistry and Molecular Medicine, CHU Sainte-Justine, University of Montreal, Montreal, Québec, Canada
| | - Carme Arnan
- Centre for Genomic Regulation (CRG), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Institut Hospital del Mar d’Investigations Mèdiques (IMIM), Barcelona, Spain
| | - Rory Johnson
- Centre for Genomic Regulation (CRG), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Institut Hospital del Mar d’Investigations Mèdiques (IMIM), Barcelona, Spain
| | - Christophe Hitte
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | - Gilles Salbert
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | - Agnès Méreau
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | - Pascale Quignon
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | - Thomas Derrien
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
| | - Catherine André
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, Rennes, France
- Université Rennes 1, UEB, Biosit, Faculté de Médecine, Rennes, France
- * E-mail: (CA); (JP)
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Abstract
Acro-osteolysis is an osteolysis of the distal phalanges of the hands and feet and can affect the terminal tuft or the shaft of the distal phalanx (transverse or band acro-osteolysis). It is often associated with distal digital ischemia, digital calcinosis, or severe sensory neuropathy. Acro-osteolysis has been associated with a heterogeneous group of disorders, including occupational activities, infections, rheumatic disorders (systemic sclerosis, psoriatic arthritis), endocrinopathies, genetic disorders, and lysosomal storage disorders. Plain radiography is the gold standard for the detection of acro-osteolysis.
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Bode H, Bourquin F, Suriyanarayanan S, Wei Y, Alecu I, Othman A, Von Eckardstein A, Hornemann T. HSAN1 mutations in serine palmitoyltransferase reveal a close structure-function-phenotype relationship. Hum Mol Genet 2015; 25:853-65. [PMID: 26681808 DOI: 10.1093/hmg/ddv611] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/12/2015] [Indexed: 12/13/2022] Open
Abstract
Hereditary sensory and autonomic neuropathy type 1 (HSAN1) is a rare autosomal dominant inherited peripheral neuropathy caused by mutations in the SPTLC1 and SPTLC2 subunits of serine palmitoyltransferase (SPT). The mutations induce a permanent shift in the substrate preference from L-serine to L-alanine, which results in the pathological formation of atypical and neurotoxic 1-deoxy-sphingolipids (1-deoxySL). Here we compared the enzymatic properties of 11 SPTLC1 and six SPTLC2 mutants using a uniform isotope labelling approach. In total, eight SPT mutants (STPLC1p.C133W, p.C133Y, p.S331F, p.S331Y and SPTLC2p.A182P, p.G382V, p.S384F, p.I504F) were associated with increased 1-deoxySL synthesis. Despite earlier reports, canonical activity with l-serine was not reduced in any of the investigated SPT mutants. Three variants (SPTLC1p.S331F/Y and SPTLC2p.I505Y) showed an increased canonical activity and increased formation of C20 sphingoid bases. These three mutations are associated with an exceptionally severe HSAN1 phenotype, and increased C20 sphingosine levels were also confirmed in plasma of patients. A principal component analysis of the analysed sphingoid bases clustered the mutations into three separate entities. Each cluster was related to a distinct clinical outcome (no, mild and severe HSAN1 phenotype). A homology model based on the protein structure of the prokaryotic SPT recapitulated the same grouping on a structural level. Mutations associated with the mild form clustered around the active site, whereas mutations associated with the severe form were located on the surface of the protein. In conclusion, we showed that HSAN1 mutations in SPT have distinct biochemical properties, which allowed for the prediction of the clinical symptoms on the basis of the plasma sphingoid base profile.
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Affiliation(s)
- Heiko Bode
- Institute for Clinical Chemistry, University Hospital Zurich, Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Florence Bourquin
- Institute of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Saranya Suriyanarayanan
- Institute for Clinical Chemistry, University Hospital Zurich, Competence Center for Personalized Medicine (CC-PM), Molecular Translation and Biomedicine (MTB), and
| | - Yu Wei
- Institute for Clinical Chemistry, University Hospital Zurich
| | - Irina Alecu
- Institute for Clinical Chemistry, University Hospital Zurich, Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Alaa Othman
- Institute for Clinical Chemistry, University Hospital Zurich, Competence Center for Personalized Medicine (CC-PM), Molecular Translation and Biomedicine (MTB), and
| | - Arnold Von Eckardstein
- Institute for Clinical Chemistry, University Hospital Zurich, Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland, Competence Center for Personalized Medicine (CC-PM), Molecular Translation and Biomedicine (MTB), and
| | - Thorsten Hornemann
- Institute for Clinical Chemistry, University Hospital Zurich, Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland, Competence Center for Personalized Medicine (CC-PM), Molecular Translation and Biomedicine (MTB), and
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Zhou K, Blom T. Trafficking and Functions of Bioactive Sphingolipids: Lessons from Cells and Model Membranes. Lipid Insights 2015; 8:11-20. [PMID: 26715852 PMCID: PMC4685176 DOI: 10.4137/lpi.s31615] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/08/2015] [Accepted: 11/10/2015] [Indexed: 12/15/2022] Open
Abstract
Ceramide and sphingosine and their phosphorylated counterparts are recognized as "bioactive sphingolipids" and modulate membrane integrity, the activity of enzymes, or act as ligands of G protein-coupled receptors. The subcellular distribution of the bioactive sphingolipids is central to their function as the same lipid can mediate diametrically opposite effects depending on its location. To ensure that these lipids are present in the right amount and in the appropriate organelles, cells employ selective lipid transport and compartmentalize sphingolipid-metabolizing enzymes to characteristic subcellular sites. Our knowledge of key mechanisms involved in sphingolipid signaling and trafficking has increased substantially in the past decades-thanks to advances in biochemical and cell biological methods. In this review, we focus on the bioactive sphingolipids and discuss how the combination of studies in cells and in model membranes have contributed to our understanding of how they behave and function in living organisms.
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Affiliation(s)
- Kecheng Zhou
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Tomas Blom
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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Kramer R, Bielawski J, Kistner-Griffin E, Othman A, Alecu I, Ernst D, Kornhauser D, Hornemann T, Spassieva S. Neurotoxic 1-deoxysphingolipids and paclitaxel-induced peripheral neuropathy. FASEB J 2015. [PMID: 26198449 DOI: 10.1096/fj.15-272567] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Peripheral neuropathy is a major dose-limiting side effect of paclitaxel and cisplatin chemotherapy. In the current study, we tested the involvement of a novel class of neurotoxic sphingolipids, the 1-deoxysphingolipids. 1-Deoxysphingolipids are produced when the enzyme serine palmitoyltransferase uses l-alanine instead of l-serine as its amino acid substrate. We tested whether treatment of cells with paclitaxel (250 nM, 1 µM) and cisplatin (250 nM, 1 µM) would result in elevated cellular levels of 1-deoxysphingolipids. Our results revealed that paclitaxel, but not cisplatin treatment, caused a dose-dependent elevation of 1-deoxysphingolipids levels and an increase in the message and activity of serine palmitoyltransferase (P < 0.05). We also tested whether there is an association between peripheral neuropathy symptoms [evaluated by the European Organization for Research and Treatment of Cancer (EORTC) QLQ-chemotherapy-induced peripheral neuropathy-20 (CIPN20) instrument] and the 1-deoxysphingolipid plasma levels (measured by mass spectrometry) in 27 patients with breast cancer who were treated with paclitaxel chemotherapy. Our results showed that there was an association between the incidence and severity of neuropathy and the levels of very-long-chain 1-deoxyceramides such as C24 (P < 0.05), with the strongest association being with motor neuropathy (P < 0.001). Our data from cells and from patients with breast cancer suggest that 1-deoxysphingolipids, the very-long-chain in particular, play a role as molecular intermediates of paclitaxel-induced peripheral neuropathy.
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Affiliation(s)
- Rita Kramer
- *Department of Medicine, Department of Biochemistry and Molecular Biology, and Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA; and Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
| | - Jacek Bielawski
- *Department of Medicine, Department of Biochemistry and Molecular Biology, and Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA; and Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
| | - Emily Kistner-Griffin
- *Department of Medicine, Department of Biochemistry and Molecular Biology, and Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA; and Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
| | - Alaa Othman
- *Department of Medicine, Department of Biochemistry and Molecular Biology, and Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA; and Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
| | - Irina Alecu
- *Department of Medicine, Department of Biochemistry and Molecular Biology, and Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA; and Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
| | - Daniela Ernst
- *Department of Medicine, Department of Biochemistry and Molecular Biology, and Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA; and Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
| | - Drew Kornhauser
- *Department of Medicine, Department of Biochemistry and Molecular Biology, and Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA; and Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
| | - Thorsten Hornemann
- *Department of Medicine, Department of Biochemistry and Molecular Biology, and Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA; and Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
| | - Stefka Spassieva
- *Department of Medicine, Department of Biochemistry and Molecular Biology, and Department of Public Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA; and Institute for Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland
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20
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Neuroprotective effect of erythropoietin against pressure ulcer in a mouse model of small fiber neuropathy. PLoS One 2014; 9:e113454. [PMID: 25422898 PMCID: PMC4244151 DOI: 10.1371/journal.pone.0113454] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/24/2014] [Indexed: 01/31/2023] Open
Abstract
An increased risk of skin pressure ulcers (PUs) is common in patients with sensory neuropathies, including those caused by diabetes mellitus. Recombinant human erythropoietin (rhEPO) has been shown to protect the skin against PUs developed in animal models of long-term diabetes. The aim of this work was to determine whether rhEPO could prevent PU formation in a mouse model of drug-inducedSFN. Functional SFN was induced by systemic injection of resiniferatoxin (RTX, 50 µg/kg, i.p.). RhEPO (3000 UI/kg, i.p.) was given the day before RTX injection and then every other day. Seven days after RTX administration, PUs were induced by applying two magnetic plates on the dorsal skin. RTX-treated mice expressed thermal and mechanical hypoalgesia and showed calcitonin gene-related peptide (CGRP) and substance P (SP) depletion without nerve degeneration or vascular dysfunction. RTX mice developed significantly larger stage 2 PUs than Vehicle mice. RhEPO prevented thermal and mechanical hypoalgesia and neuropeptide depletion in small nerve fibers. RhEPO increased hematocrit and altered endothelium-dependent vasodilatation without any effect on PU formation in Vehicle mice. The characteristics of PUs in RTX mice treated with rhEPO and Vehicle mice were found similar. In conclusion, RTX appeared to increased PU development through depletion of CGRP and SP in small nerve fibers, whereas systemic rhEPO treatment had beneficial effect on peptidergic nerve fibers and restored skin protective capacities against ischemic pressure. Our findings support the evaluation of rhEPO and/or its non-hematopoietic analogs in preventing to prevent PUs in patients with SFN.
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Wei N, Pan J, Pop-Busui R, Othman A, Alecu I, Hornemann T, Eichler FS. Altered sphingoid base profiles in type 1 compared to type 2 diabetes. Lipids Health Dis 2014; 13:161. [PMID: 25305670 PMCID: PMC4271467 DOI: 10.1186/1476-511x-13-161] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 09/27/2014] [Indexed: 11/29/2022] Open
Abstract
Background Sphingolipids are increasingly recognized to play a role in insulin resistance and diabetes. Recently we reported significant elevations of 1-deoxysphingolipids (1-deoxySL) - an atypical class of sphingolipids in patients with metabolic syndrome (MetS) and diabetes type 2 (T2DM). It is unknown whether 1-deoxySL in patients with diabetes type 1 (T1DM) are similarly elevated. Findings We analyzed the long chain base profile by LC-MS after hydrolyzing the N-acyl and O-linked headgroups in plasma from individuals with T1DM (N = 27), T2DM (N = 30) and healthy controls (N = 23). 1-deoxySLs were significantly higher in the groups with T2DM but not different between T1DM and controls. In contrast to patients with T2DM, 1-deoxSL levels are not elevated in T1DM. Conclusions Our study indicates that the 1-deoxySL formation is not per-se caused by hyperglycemia but rather specifically associated with metabolic changes in T2DM, such as elevated triglyceride levels. Electronic supplementary material The online version of this article (doi:10.1186/1476-511X-13-161) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | - Florian S Eichler
- MGH Neuroscience Center, Department of Neurology, Harvard Medical School, 55 Fruit Street ACC 708, Boston, MA 02114, USA.
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Sergeeva OA, Tran MT, Haase-Pettingell C, King JA. Biochemical characterization of mutants in chaperonin proteins CCT4 and CCT5 associated with hereditary sensory neuropathy. J Biol Chem 2014; 289:27470-80. [PMID: 25124038 DOI: 10.1074/jbc.m114.576033] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hereditary sensory neuropathies are a class of disorders marked by degeneration of the nerve fibers in the sensory periphery neurons. Recently, two mutations were identified in the subunits of the eukaryotic cytosolic chaperonin TRiC, a protein machine responsible for folding actin and tubulin in the cell. C450Y CCT4 was identified in a stock of Sprague-Dawley rats, whereas H147R CCT5 was found in a human Moroccan family. As with many genetically identified mutations associated with neuropathies, the underlying molecular basis of the mutants was not defined. We investigated the biochemical properties of these mutants using an expression system in Escherichia coli that produces homo-oligomeric rings of CCT4 and CCT5. Full-length versions of both mutant protein chains were expressed in E. coli at levels approaching that of the WT chains. Sucrose gradient centrifugation revealed chaperonin-sized complexes of both WT and mutant chaperonins, but with reduced recovery of C450Y CCT4 soluble subunits. Electron microscopy of negatively stained samples of C450Y CCT4 revealed few ring-shaped species, whereas WT CCT4, H147R CCT5, and WT CCT5 revealed similar ring structures. CCT5 complexes were assayed for their ability to suppress aggregation of and refold the model substrate γd-crystallin, suppress aggregation of mutant huntingtin, and refold the physiological substrate β-actin in vitro. H147R CCT5 was not as efficient in chaperoning these substrates as WT CCT5. The subtle effects of these mutations are consistent with the homozygous disease phenotype, in which most functions are carried out during development and adulthood, but some selective function is lost or reduced.
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Affiliation(s)
- Oksana A Sergeeva
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Meme T Tran
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Cameron Haase-Pettingell
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Jonathan A King
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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24
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Macefield VG, Norcliffe-Kaufmann L, Axelrod FB, Kaufmann H. Cardiac-locked bursts of muscle sympathetic nerve activity are absent in familial dysautonomia. J Physiol 2012; 591:689-700. [PMID: 23165765 DOI: 10.1113/jphysiol.2012.246264] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Familial dysautonomia (Riley-Day syndrome) is an hereditary sensory and autonomic neuropathy (HSAN type III), expressed at birth, that is associated with reduced pain and temperature sensibilities and absent baroreflexes, causing orthostatic hypotension as well as labile blood pressure that increases markedly during emotional excitement. Given the apparent absence of functional baroreceptor afferents, we tested the hypothesis that the normal cardiac-locked bursts of muscle sympathetic nerve activity (MSNA) are absent in patients with familial dysautonomia. Tungsten microelectrodes were inserted percutaneously into muscle or cutaneous fascicles of the common peroneal nerve in 12 patients with familial dysautonomia. Spontaneous bursts of MSNA were absent in all patients, but in five patients we found evidence of tonically firing sympathetic neurones, with no cardiac rhythmicity, that increased their spontaneous discharge during emotional arousal but not during a manoeuvre that unloads the baroreceptors. Conversely, skin sympathetic nerve activity (SSNA), recorded in four patients, appeared normal. We conclude that the loss of phasic bursts of MSNA and the loss of baroreflex modulation of muscle vasoconstrictor drive contributes to the poor control of blood pressure in familial dysautonomia, and that the increase in tonic firing of muscle vasoconstrictor neurones contributes to the increase in blood pressure during emotional excitement.
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Biegstraaten M, Hollak CEM, Bakkers M, Faber CG, Aerts JMFG, van Schaik IN. Small fiber neuropathy in Fabry disease. Mol Genet Metab 2012; 106:135-41. [PMID: 22497776 DOI: 10.1016/j.ymgme.2012.03.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 03/15/2012] [Accepted: 03/15/2012] [Indexed: 02/05/2023]
Abstract
Previous studies have explicitly shown that small nerve fibers are affected in Fabry disease which is assumed to cause the severe neuropathic pain that patients may have from childhood on. Neuropathic pain and small fiber neuropathy characteristics have therefore been considered as appropriate study endpoints in studies on the efficacy of enzyme replacement therapy. However, the relationship between small fiber neuropathy characteristics and pain, as well as the course of small fiber neuropathy in Fabry disease is still uncertain. In this article a comprehensive overview of the existing literature on small nerve fiber function and structure and the relationship with pain, age and disease severity is presented supplemented with data from the Dutch Fabry cohort, with the aim to identify consensus as well as controversies and to propose a hypothesis on the evolution of neuropathy in Fabry disease.
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Affiliation(s)
- Marieke Biegstraaten
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Academic Medical Center, Amsterdam, The Netherlands.
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26
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Koy A, Freynhagen R, Mayatepek E, Tibussek D. Hereditary sensory and autonomic neuropathy with autonomic crises: a Turkish variant of familial dysautonomia? J Child Neurol 2012; 27:191-6. [PMID: 22140130 DOI: 10.1177/0883073811416664] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Hereditary sensory and autonomic neuropathies have different phenotypes. We report 2 cousins with differing clinical courses of a hereditary sensory and autonomic neuropathy. The progressive disease in case 1 is dominated by loss of sensation, autonomic crises, and pain. Case 2 shows loss of sensation, mental retardation, and deafness, clinically similar to patients with hereditary sensory and autonomic neuropathy type II. Detailed molecular studies in case 1 for all known genes that are associated with hereditary sensory and autonomic neuropathies were negative. However, the occurrence of the 2 cases within 1 kindred makes a common genetic background likely. We, therefore, propose a Turkish variant of familial dysautonomia in these 2 patients.
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Affiliation(s)
- Anne Koy
- Department of General Pediatrics, University Children's Hospital Düsseldorf, Germany.
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Rotthier A, Baets J, Timmerman V, Janssens K. Mechanisms of disease in hereditary sensory and autonomic neuropathies. Nat Rev Neurol 2012; 8:73-85. [PMID: 22270030 DOI: 10.1038/nrneurol.2011.227] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Hereditary sensory and autonomic neuropathies (HSANs) are a clinically and genetically heterogeneous group of disorders of the PNS. Progressive degeneration, predominantly of sensory and autonomic neurons, is the main pathological feature in patients with HSAN, and causes prominent sensory loss and ulcerative mutilations in combination with variable autonomic and motor disturbances. Advances in molecular genetics have enabled identification of disease-causing mutations in 12 genes, and studies on the functional effects of these mutations are underway. Although some of the affected proteins--such as nerve growth factor and its receptor--have obvious nerve-specific roles, others are ubiquitously expressed proteins that are involved in sphingolipid metabolism, vesicular transport, transcription regulation and structural integrity. An important challenge in the future will be to understand the common molecular pathways that result in HSANs. Unraveling the mechanisms that underlie sensory and autonomic neurodegeneration could assist in identifying targets for future therapeutic strategies in patients with HSAN. This Review highlights key advances in the understanding of HSANs, including insights into the molecular mechanisms of disease, derived from genetic studies of patients with these disorders.
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Affiliation(s)
- Annelies Rotthier
- VIB Department of Molecular Genetics, University of Antwerp, Universiteitsplein 1, 2610 Antwerpen, Belgium
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Abstract
An estimated 15-50% of the population experiences pain at any given time, at great personal and societal cost. Pain is the most common reason patients seek medical attention, and there is a high degree of individual variability in reporting the incidence and severity of symptoms. Research suggests that pain sensitivity and risk for chronic pain are complex heritable traits of polygenic origin. Animal studies and candidate gene testing in humans have provided some progress in understanding the heritability of pain, but the application of the genome-wide association methodology offers a new tool for further elucidating the genetic contributions to normal pain responding and pain in clinical populations. Although the determination of the genetics of pain is still in its infancy, it is clear that a number of genes play a critical role in determining pain sensitivity or susceptibility to chronic pain. This review presents an update of the most recent findings that associate genetic variation with variability in pain and an overview of the candidate genes with the highest translational potential.
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Affiliation(s)
- Erin E Young
- Department of Anesthesiology, Molecular Epidemiology of Pain Program, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
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Holzer P. Transient receptor potential (TRP) channels as drug targets for diseases of the digestive system. Pharmacol Ther 2011; 131:142-70. [PMID: 21420431 PMCID: PMC3107431 DOI: 10.1016/j.pharmthera.2011.03.006] [Citation(s) in RCA: 172] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 03/01/2011] [Indexed: 12/12/2022]
Abstract
Approximately 20 of the 30 mammalian transient receptor potential (TRP) channel subunits are expressed by specific neurons and cells within the alimentary canal. They subserve important roles in taste, chemesthesis, mechanosensation, pain and hyperalgesia and contribute to the regulation of gastrointestinal motility, absorptive and secretory processes, blood flow, and mucosal homeostasis. In a cellular perspective, TRP channels operate either as primary detectors of chemical and physical stimuli, as secondary transducers of ionotropic or metabotropic receptors, or as ion transport channels. The polymodal sensory function of TRPA1, TRPM5, TRPM8, TRPP2, TRPV1, TRPV3 and TRPV4 enables the digestive system to survey its physical and chemical environment, which is relevant to all processes of digestion. TRPV5 and TRPV6 as well as TRPM6 and TRPM7 contribute to the absorption of Ca²⁺ and Mg²⁺, respectively. TRPM7 participates in intestinal pacemaker activity, and TRPC4 transduces muscarinic acetylcholine receptor activation to smooth muscle contraction. Changes in TRP channel expression or function are associated with a variety of diseases/disorders of the digestive system, notably gastro-esophageal reflux disease, inflammatory bowel disease, pain and hyperalgesia in heartburn, functional dyspepsia and irritable bowel syndrome, cholera, hypomagnesemia with secondary hypocalcemia, infantile hypertrophic pyloric stenosis, esophageal, gastrointestinal and pancreatic cancer, and polycystic liver disease. These implications identify TRP channels as promising drug targets for the management of a number of gastrointestinal pathologies. As a result, major efforts are put into the development of selective TRP channel agonists and antagonists and the assessment of their therapeutic potential.
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Affiliation(s)
- Peter Holzer
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz, Austria.
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Lack of collagen XV impairs peripheral nerve maturation and, when combined with laminin-411 deficiency, leads to basement membrane abnormalities and sensorimotor dysfunction. J Neurosci 2010; 30:14490-501. [PMID: 20980607 DOI: 10.1523/jneurosci.2644-10.2010] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Although the Schwann cell basement membrane (BM) is required for normal Schwann cell terminal differentiation, the role of BM-associated collagens in peripheral nerve maturation is poorly understood. Collagen XV is a BM zone component strongly expressed in peripheral nerves, and we show that its absence in mice leads to loosely packed axons in C-fibers and polyaxonal myelination. The simultaneous lack of collagen XV and another peripheral nerve component affecting myelination, laminin α4, leads to severely impaired radial sorting and myelination, and the maturation of the nerve is permanently compromised, contrasting with the slow repair observed in Lama4-/- single knock-out mice. Moreover, the Col15a1-/-;Lama4-/- double knock-out (DKO) mice initially lack C-fibers and, even over 1 year of age have only a few, abnormal C-fibers. The Lama4-/- knock-out results in motor and tactile sensory impairment, which is exacerbated by a simultaneous Col15a1-/- knock-out, whereas sensitivity to heat-induced pain is increased in the DKO mice. Lack of collagen XV results in slower sensory nerve conduction, whereas the Lama4-/- and DKO mice exhibit increased sensory nerve action potentials and decreased compound muscle action potentials; x-ray diffraction revealed less mature myelin in the sciatic nerves of the latter than in controls. Ultrastructural analyses revealed changes in the Schwann cell BM in all three mutants, ranging from severe (DKO) to nearly normal (Col15a1-/-). Collagen XV thus contributes to peripheral nerve maturation and C-fiber formation, and its simultaneous deletion from neural BM zones with laminin α4 leads to a DKO phenotype distinct from those of both single knock-outs.
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Braunstein KE, Eschbach J, Ròna-Vörös K, Soylu R, Mikrouli E, Larmet Y, René F, Gonzalez De Aguilar JL, Loeffler JP, Müller HP, Bucher S, Kaulisch T, Niessen HG, Tillmanns J, Fischer K, Schwalenstöcker B, Kassubek J, Pichler B, Stiller D, Petersen A, Ludolph AC, Dupuis L. A point mutation in the dynein heavy chain gene leads to striatal atrophy and compromises neurite outgrowth of striatal neurons. Hum Mol Genet 2010; 19:4385-98. [PMID: 20807776 DOI: 10.1093/hmg/ddq361] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The molecular motor dynein and its associated regulatory subunit dynactin have been implicated in several neurodegenerative conditions of the basal ganglia, such as Huntington's disease (HD) and Perry syndrome, an atypical Parkinson-like disease. This pathogenic role has been largely postulated from the existence of mutations in the dynactin subunit p150(Glued). However, dynactin is also able to act independently of dynein, and there is currently no direct evidence linking dynein to basal ganglia degeneration. To provide such evidence, we used here a mouse strain carrying a point mutation in the dynein heavy chain gene that impairs retrograde axonal transport. These mice exhibited motor and behavioural abnormalities including hindlimb clasping, early muscle weakness, incoordination and hyperactivity. In vivo brain imaging using magnetic resonance imaging showed striatal atrophy and lateral ventricle enlargement. In the striatum, altered dopamine signalling, decreased dopamine D1 and D2 receptor binding in positron emission tomography SCAN and prominent astrocytosis were observed, although there was no neuronal loss either in the striatum or substantia nigra. In vitro, dynein mutant striatal neurons displayed strongly impaired neuritic morphology. Altogether, these findings provide a direct genetic evidence for the requirement of dynein for the morphology and function of striatal neurons. Our study supports a role for dynein dysfunction in the pathogenesis of neurodegenerative disorders of the basal ganglia, such as Perry syndrome and HD.
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Bertea M, Rütti MF, Othman A, Marti-Jaun J, Hersberger M, von Eckardstein A, Hornemann T. Deoxysphingoid bases as plasma markers in diabetes mellitus. Lipids Health Dis 2010; 9:84. [PMID: 20712864 PMCID: PMC2931514 DOI: 10.1186/1476-511x-9-84] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 08/16/2010] [Indexed: 01/13/2023] Open
Abstract
Background Sphingoid bases are formed from the precursors L-serine and palmitoyl-CoA-a reaction which is catalyzed by the serine-palmitoyltransferase (SPT). SPT metabolizes, besides palmitoyl-CoA also other acyl-CoAs but shows also variability towards the use of other amino acid substrates. The enzyme is also able to metabolize alanine, which results in the formation of an atypical deoxy-sphingoid base (DSB). This promiscuous activity is greatly increased in the case of the sensory neuropathy HSAN1, and pathologically elevated DSB levels have been identified as the cause of this disease. Clinically, HSAN1 shows a pronounced similarity to the diabetic sensory neuropathy (DSN), which is the most common chronic complication of diabetes mellitus. Since serine and alanine metabolism is functionally linked to carbohydrate metabolism by their precursors 3-phosphoglycerate and pyruvate, we were interested to see whether the levels of certain sphingoid base metabolites are altered in patients with diabetes. Results In a case-control study we compared plasma sphingoid base levels between healthy and diabetic individuals. DSB levels were higher in the diabetic group whereas C16 and C18 sphingoid bases were not significantly different. Plasma serine, but not alanine levels were lower in the diabetic group. A subsequent lipoprotein fractionation showed that the DSBs are primarily present in the LDL and VLDL fraction. Conclusion Our results suggest that DSBs are a novel category of plasma biomarkers in diabetes which reflect functional impairments of carbohydrate metabolism. Furthermore, elevated DSB levels as we see them in diabetic patients might also contribute to the progression of the diabetic sensory neuropathy, the most frequent complication of diabetes.
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Affiliation(s)
- Mariana Bertea
- Institute for Clinical Chemistry, University Hospital Zurich and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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Canine inherited motor and sensory neuropathies: an updated classification in 22 breeds and comparison to Charcot-Marie-Tooth disease. Vet J 2010; 188:274-85. [PMID: 20638305 DOI: 10.1016/j.tvjl.2010.06.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 06/01/2010] [Accepted: 06/04/2010] [Indexed: 12/15/2022]
Abstract
Canine inherited neuropathies form a group of degenerative diseases affecting motor and/or sensory and autonomic peripheral nerves. There is now a large number of inherited motor and sensory neuropathies (IMSN) reported in the veterinary literature, for which clinical, electrophysiological, histopathological and mode of inheritance data are available. Their resemblance with Charcot-Marie-Tooth disease in humans is suggested, although direct comparison is difficult due to the small number of cases described in each breed and the lack of genetic knowledge in dogs. Charcot-Marie-Tooth disease forms a wide group of hereditary neuropathies for which a genetic mutation is recognised in more than 70% of patients. In dogs, no genetic mutation has so far been identified and the knowledge available for human hereditary neuropathies may be useful to identify genetic mutations in dogs. This review provides an update on data available on inherited neuropathy in Leonberger dogs and three new degenerative neuropathies are briefly described in two Russian Black terriers, two Cocker Spaniels and a Podhale Shepherd dog.
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Xu YH, Barnes S, Sun Y, Grabowski GA. Multi-system disorders of glycosphingolipid and ganglioside metabolism. J Lipid Res 2010; 51:1643-75. [PMID: 20211931 DOI: 10.1194/jlr.r003996] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Glycosphingolipids (GSLs) and gangliosides are a group of bioactive glycolipids that include cerebrosides, globosides, and gangliosides. These lipids play major roles in signal transduction, cell adhesion, modulating growth factor/hormone receptor, antigen recognition, and protein trafficking. Specific genetic defects in lysosomal hydrolases disrupt normal GSL and ganglioside metabolism leading to their excess accumulation in cellular compartments, particularly in the lysosome, i.e., lysosomal storage diseases (LSDs). The storage diseases of GSLs and gangliosides affect all organ systems, but the central nervous system (CNS) is primarily involved in many. Current treatments can attenuate the visceral disease, but the management of CNS involvement remains an unmet medical need. Early interventions that alter the CNS disease have shown promise in delaying neurologic involvement in several CNS LSDs. Consequently, effective treatment for such devastating inherited diseases requires an understanding of the early developmental and pathological mechanisms of GSL and ganglioside flux (synthesis and degradation) that underlie the CNS diseases. These are the focus of this review.
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Affiliation(s)
- You-Hai Xu
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center and the Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229-3039, USA
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Penno A, Reilly MM, Houlden H, Laurá M, Rentsch K, Niederkofler V, Stoeckli ET, Nicholson G, Eichler F, Brown RH, von Eckardstein A, Hornemann T. Hereditary sensory neuropathy type 1 is caused by the accumulation of two neurotoxic sphingolipids. J Biol Chem 2010; 285:11178-87. [PMID: 20097765 DOI: 10.1074/jbc.m109.092973] [Citation(s) in RCA: 263] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
HSAN1 is an inherited neuropathy found to be associated with several missense mutations in the SPTLC1 subunit of serine palmitoyltransferase (SPT). SPT catalyzes the condensation of serine and palmitoyl-CoA, the initial step in the de novo synthesis of sphingolipids. Here we show that the HSAN1 mutations induce a shift in the substrate specificity of SPT, which leads to the formation of the two atypical deoxy-sphingoid bases (DSBs) 1-deoxy-sphinganine and 1-deoxymethyl-sphinganine. Both metabolites lack the C(1) hydroxyl group of sphinganine and can therefore neither be converted to complex sphingolipids nor degraded. Consequently, they accumulate in the cell, as demonstrated in HEK293 cells overexpressing mutant SPTLC1 and lymphoblasts of HSAN1 patients. Elevated DSB levels were also found in the plasma of HSAN1 patients and confirmed in three groups of HSAN1 patients with different SPTLC1 mutations. The DSBs show pronounced neurotoxic effects on neurite formation in cultured sensory neurons. The neurotoxicity co-occurs with a disturbed neurofilament structure in neurites when cultured in the presence of DSBs. Based on these observations, we conclude that HSAN1 is caused by a gain of function mutation, which results in the formation of two atypical and neurotoxic sphingolipid metabolites.
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Affiliation(s)
- Anke Penno
- Institute for Clinical Chemistry, University Hospital Zurich, Raemistrasse 100, CH-8091 Zurich, Switzerland
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Abstract
The endocytosis pathway controls multiple cellular and physiological events. The lysosome is the destination of newly synthesized lysosomal hydrolytic enzymes. Internalized molecules or particles are delivered to the lysosome for degradation through sequential transport along the endocytic pathway. The endocytic pathway is also emerging as a signalling platform, in addition to the well-known role of the plasma membrane for signalling. Rab7 is a late endosome-/lysosome-associated small GTPase, perhaps the only lysosomal Rab protein identified to date. Rab7 plays critical roles in the endocytic processes. Through interaction with its partners (including upstream regulators and downstream effectors), Rab7 participates in multiple regulation mechanisms in endosomal sorting, biogenesis of lysosome [or LRO (lysosome-related organelle)] and phagocytosis. These processes are closely related to substrates degradation, antigen presentation, cell signalling, cell survival and microbial pathogen infection. Consistently, mutations or dysfunctions of Rab7 result in traffic disorders, which cause various diseases, such as neuropathy, cancer and lipid metabolism disease. Rab7 also plays important roles in microbial pathogen infection and survival, as well as in participating in the life cycle of viruses. Here, we give a brief review on the central role of Rab7 in endosomal traffic and summarize the studies focusing on the participation of Rab7 in disease pathogenesis. The underlying mechanism governed by Rab7 and its partners will also be discussed.
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A systematic comparison of all mutations in hereditary sensory neuropathy type I (HSAN I) reveals that the G387A mutation is not disease associated. Neurogenetics 2009; 10:135-43. [PMID: 19132419 DOI: 10.1007/s10048-008-0168-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 12/09/2008] [Indexed: 10/21/2022]
Abstract
Hereditary sensory neuropathy type 1 (HSAN I) is an autosomal dominant inherited neurodegenerative disorder of the peripheral nervous system associated with mutations in the SPTLC1 subunit of the serine palmitoyltransferase (SPT). Four missense mutations (C133W, C133Y, V144D and G387A) in SPTLC1 were reported to cause HSAN I. SPT catalyses the condensation of Serine and Palmitoyl-CoA, which is the first and rate-limiting step in the de novo synthesis of ceramides. Earlier studies showed that C133W and C133Y mutants have a reduced activity, whereas the impact of the V144D and G387A mutations on the human enzyme was not tested yet. In this paper, we show that none of the HSAN I mutations interferes with SPT complex formation. We demonstrate that also V144D has a reduced SPT activity, however to a lower extent than C133W and C133Y. In contrast, the G387A mutation showed no influence on SPT activity. Furthermore, the growth phenotype of LY-B cells--a SPTLC1 deficient CHO cell line--could be reversed by expressing either the wild-type SPTLC1 or the G387A mutant, but not the C133W mutant. This indicates that the G387A mutation is most likely not directly associated with HSAN I. These findings were genetically confirmed by the identification of a nuclear HSAN family which showed segregation of the G387A variant as a non-synonymous SNP.
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