1
|
Liu J, He Y, Lwin C, Han M, Guan B, Naik A, Bender C, Moore N, Huryn LA, Sergeev YV, Qian H, Zeng Y, Dong L, Liu P, Lei J, Haugen CJ, Prasov L, Shi R, Dollfus H, Aristodemou P, Laich Y, Németh AH, Taylor J, Downes S, Krawczynski MR, Meunier I, Strassberg M, Tenney J, Gao J, Shear MA, Moore AT, Duncan JL, Menendez B, Hull S, Vincent AL, Siskind CE, Traboulsi EI, Blackstone C, Sisk RA, Miraldi Utz V, Webster AR, Michaelides M, Arno G, Synofzik M, Hufnagel RB. Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders. Brain 2024; 147:2085-2097. [PMID: 38735647 PMCID: PMC11146429 DOI: 10.1093/brain/awae055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 01/08/2024] [Accepted: 01/28/2024] [Indexed: 05/14/2024] Open
Abstract
Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism and hair anomalies. PNPLA6 encodes neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a systematic evidence-based review of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6-associated clinical diagnoses unambiguously reclassified 36 variants as pathogenic and 10 variants as likely pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship, and the generation of a preclinical animal model, pave the way for therapeutic trials, using NTE as a biomarker.
Collapse
Affiliation(s)
- James Liu
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yi He
- Fermentation Facility, Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD 20892, USA
| | - Cara Lwin
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Marina Han
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Bin Guan
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Amelia Naik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chelsea Bender
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Nia Moore
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Laryssa A Huryn
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yuri V Sergeev
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yong Zeng
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lijin Dong
- Genetic Engineering Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Pinghu Liu
- Genetic Engineering Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jingqi Lei
- Genetic Engineering Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Carl J Haugen
- Genetic Engineering Core, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lev Prasov
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, MI 48105, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48105, USA
| | - Ruifang Shi
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, 100730 Beijing, China
| | - Hélène Dollfus
- Centre de référence pour les Affections Rares Ophtalmologiques CARGO, Hôpitaux Universitaires de Strasbourg, Université de Strasbourg, UMRS_1112, Strasbourg 67091, France
| | - Petros Aristodemou
- Cyprus Institute of Neurology and Genetics, Nicosia 1683, Cyprus
- VRMCy Centre, Limassol 3025, Cyprus
| | - Yannik Laich
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- Department of Genetics, Moorfields Eye Hospital NHS Trust, London EC1V 2PD, UK
| | - Andrea H Németh
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, ACE Building, Nuffield Orthopaedic Centre, Oxford OX3 7HE, UK
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - John Taylor
- Oxford Regional Genetics Laboratory, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Susan Downes
- Nuffield Department of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Maciej R Krawczynski
- Department of Medical Genetics, Poznan University of Medical Sciences, Poznan 60-512, Poland
| | - Isabelle Meunier
- National Referent Centre for Rare Sensory Diseases, Montpellier University Hospital, Montpellier University, Montpellier 34295, France
| | | | - Jessica Tenney
- Division of Medical Genetics, Department of Pediatrics, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Josephine Gao
- Division of Medical Genetics, Department of Pediatrics, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Matthew A Shear
- Division of Medical Genetics, Department of Pediatrics, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Anthony T Moore
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- Department of Ophthalmology, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Jacque L Duncan
- Department of Ophthalmology, UCSF School of Medicine, San Francisco, CA 94143, USA
| | - Beatriz Menendez
- Department of Pediatrics, University of Illinois School of Medicine, Chicago, IL 60612, USA
| | - Sarah Hull
- Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand
| | - Andrea L Vincent
- Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand
| | - Carly E Siskind
- Neurology and Neurological Sciences, Stanford School of Medicine, Stanford, CA 94305, USA
| | - Elias I Traboulsi
- The Center for Genetic Eye Diseases, The Cleveland Clinic Eye Institute, Cleveland, OH 44106, USA
| | - Craig Blackstone
- Movement Disorders Division, Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Robert A Sisk
- Department of Ophthalmology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Virginia Miraldi Utz
- Department of Ophthalmology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
- Abrahamson Pediatric Eye Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Andrew R Webster
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- Department of Genetics, Moorfields Eye Hospital NHS Trust, London EC1V 2PD, UK
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- Department of Genetics, Moorfields Eye Hospital NHS Trust, London EC1V 2PD, UK
| | - Gavin Arno
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- Department of Genetics, Moorfields Eye Hospital NHS Trust, London EC1V 2PD, UK
| | - Matthis Synofzik
- Division Translational Genomics of Neurodegenerative Diseases Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen 72076, Germany
- German Center of Neurodegenerative Diseases (DZNE), Tübingen 72076, Germany
| | - Robert B Hufnagel
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Department of Genetics and Center for Integrated Healthcare Research, Kaiser Permanente Hawaii Region, Honolulu, HI 98619, USA
| |
Collapse
|
2
|
Abstract
BACKGROUND Variants in the patatin-like phospholipase domain containing 6 (PNPLA6) gene cause a broad spectrum of neurological disorders characterized by gait disturbance, visual impairment, anterior hypopituitarism, and hair anomalies. This review examines the clinical, cellular, and biochemical features found across the five PNPLA6-related diseases, with a focus on future questions to be addressed. MATERIALS AND METHODS A literature review was performed on published clinical reports on patients with PNPLA6 variants. Additionally, in vitro and in vivo models used to study the encoded protein, Neuropathy Target Esterase (NTE), are summarized to lend mechanistic perspective to human diseases. RESULTS Biallelic pathogenic PNPLA6 variants cause five systemic neurological disorders: spastic paraplegia type 39, Gordon-Holmes, Boucher-Neuhäuser, Laurence-Moon, and Oliver-McFarlane syndromes. PNPLA6 encodes NTE, an enzyme involved in maintaining phospholipid homeostasis and trafficking in the nervous system. Retinal disease presents with a unique chorioretinal dystrophy that is phenotypically similar to choroideremia and Leber congenital amaurosis. Animal and cellular models support a loss-of-function mechanism. CONCLUSIONS Clinicians should be aware of choroideremia-like ocular presentation in patients who also experience growth defects, motor dysfunction, and/or hair anomalies. Although NTE biochemistry is well characterized, further research on the relationship between genotype and the presence or absence of retinopathy should be explored to improve diagnosis and prognosis.
Collapse
Affiliation(s)
- James Liu
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Robert B Hufnagel
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| |
Collapse
|
3
|
Liu J, He Y, Lwin C, Han M, Guan B, Naik A, Bender C, Moore N, Huryn LA, Sergeev Y, Qian H, Zeng Y, Dong L, Liu P, Lei J, Haugen CJ, Prasov L, Shi R, Dollfus H, Aristodemou P, Laich Y, Németh AH, Taylor J, Downes S, Krawczynski M, Meunier I, Strassberg M, Tenney J, Gao J, Shear MA, Moore AT, Duncan JL, Menendez B, Hull S, Vincent A, Siskind CE, Traboulsi EI, Blackstone C, Sisk R, Utz V, Webster AR, Michaelides M, Arno G, Synofzik M, Hufnagel RB. Neuropathy target esterase activity predicts retinopathy among PNPLA6 disorders. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.09.544373. [PMID: 37333224 PMCID: PMC10274907 DOI: 10.1101/2023.06.09.544373] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism, and hair anomalies. PNPLA6 encodes Neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a clinical meta-analysis of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6 -associated clinical diagnoses unambiguously reclassified 10 variants as likely pathogenic and 36 variants as pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship and the generation of a preclinical animal model pave the way for therapeutic trials, using NTE as a biomarker.
Collapse
|
4
|
Lulić AM, Katalinić M. The PNPLA family of enzymes: characterisation and biological role. Arh Hig Rada Toksikol 2023; 74:75-89. [PMID: 37357879 PMCID: PMC10291501 DOI: 10.2478/aiht-2023-74-3723] [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: 02/01/2023] [Revised: 02/01/2023] [Accepted: 05/01/2023] [Indexed: 06/27/2023] Open
Abstract
This paper brings a brief review of the human patatin-like phospholipase domain-containing protein (PNPLA) family. Even though it consists of only nine members, their physiological roles and mechanisms of their catalytic activity are not fully understood. However, the results of a number of knock-out and gain- or loss-of-function research models suggest that these enzymes have an important role in maintaining the homeostasis and integrity of organelle membranes, in cell growth, signalling, cell death, and the metabolism of lipids such as triacylglycerol, phospholipids, ceramides, and retinyl esters. Research has also revealed a connection between PNPLA family member mutations or irregular catalytic activity and the development of various diseases. Here we summarise important findings published so far and discuss their structure, localisation in the cell, distribution in the tissues, specificity for substrates, and their potential physiological role, especially in view of their potential as drug targets.
Collapse
Affiliation(s)
- Ana-Marija Lulić
- Institute for Medical Research and Occupational Health, Biochemistry and Organic Analytical Chemistry Unit, Zagreb, Croatia
| | - Maja Katalinić
- Institute for Medical Research and Occupational Health, Biochemistry and Organic Analytical Chemistry Unit, Zagreb, Croatia
| |
Collapse
|
5
|
Miš K, Lulić AM, Marš T, Pirkmajer S, Katalinić M. Insulin, dibutyryl-cAMP, and glucose modulate expression of patatin-like domain containing protein 7 in cultured human myotubes. Front Endocrinol (Lausanne) 2023; 14:1139303. [PMID: 37033214 PMCID: PMC10073714 DOI: 10.3389/fendo.2023.1139303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 03/06/2023] [Indexed: 04/11/2023] Open
Abstract
Expression of patatin-like phospholipase domain containing protein 7 (PNPLA7), also known as neuropathy target esterase-related esterase (NRE), a lysophospholipase, increases with fasting and decreases with feeding in mouse skeletal muscle, indicating it is regulated by insulin, counterregulatory hormones, such as glucocorticoids and catecholamines, and/or nutrients. In cultured mouse adipocytes insulin reduces Pnpla7 expression, underscoring the possibility that insulin regulates PNPLA7 in skeletal muscle. The first aim of this study was to establish whether PNPLA7 is functionally expressed in cultured human skeletal muscle cells. The second aim was to determine whether PNPLA7 is regulated by insulin, glucocorticoids, cAMP/protein kinase A pathway, and/or glucose. Cultured human skeletal muscle cells expressed PNPLA7 mRNA and protein. Gene silencing of PNPLA7 in myoblasts reduced the phosphorylation of 70 kDa ribosomal protein S6 kinase and ribosomal protein S6 as well as the abundance of α1-subunit of Na+,K+-ATPase and acetyl-CoA carboxylase, indirectly suggesting that PNPLA7 is functionally important. In myotubes, insulin suppressed PNPLA7 mRNA at 1 g/L glucose, but not at low (0.5 g/L) or high (4.5 g/L) concentrations. Treatment with synthetic glucocorticoid dexamethasone and activator of adenylyl cyclase forskolin had no effect on PNPLA7 regardless of glucose concentration, while dibutyryl-cAMP, a cell-permeable cAMP analogue, suppressed PNPLA7 mRNA at 4.5 g/L glucose. The abundance of PNPLA7 protein correlated inversely with the glucose concentrations. Collectively, our results highlight that PNPLA7 in human myotubes is regulated by metabolic signals, implicating a role for PNPLA7 in skeletal muscle energy metabolism.
Collapse
Affiliation(s)
- Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Ana-Marija Lulić
- Biochemistry and Organic Analytical Chemistry Unit, Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Tomaž Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- *Correspondence: Sergej Pirkmajer, ; Maja Katalinić,
| | - Maja Katalinić
- Biochemistry and Organic Analytical Chemistry Unit, Institute for Medical Research and Occupational Health, Zagreb, Croatia
- *Correspondence: Sergej Pirkmajer, ; Maja Katalinić,
| |
Collapse
|
6
|
Wu S, Sun Z, Zhu T, Weleber RG, Yang P, Wei X, Pennesi ME, Sui R. Novel variants in PNPLA6 causing syndromic retinal dystrophy. Exp Eye Res 2020; 202:108327. [PMID: 33141049 DOI: 10.1016/j.exer.2020.108327] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/15/2020] [Accepted: 10/20/2020] [Indexed: 12/18/2022]
Abstract
PNPLA6-related disorders include several phenotypes, such as Boucher-Neuhäuser syndrome, Gordon Holmes syndrome, spastic paraplegia, photoreceptor degeneration, Oliver-McFarlane syndrome and Laurence-Moon syndrome. In this study, detailed clinical evaluations and genetic testing were performed in five (4 Chinese and 1 Caucasian/Chinese) syndromic retinal dystrophy patients. Genotype-phenotype correlations were analyzed based on review of the literatures of previously published PNPLA6-related cases. The mean age of patients and at first visit were 20.8 years (11, 12, 25, 28, 28) and 14.2 years (4, 7, 11, 24, 25), respectively. They all presented with severe chorioretinal dystrophy and profoundly decreased vision. The best corrected visual acuity (BCVA) ranged from 20/200 to 20/2000. Systemic manifestations included cerebellar ataxia, hypogonadotropic hypogonadism and hair anomalies. Six novel and three reported pathogenic variants in PNPLA6 (NM_001166111) were identified. The genotypes of the five cases are: c.3134C > T (p.Ser1045Leu) and c.3846+1G > A, c.3547C > T (p.Arg1183Trp) and c.1841+3A > G, c.3436G > A (p.Ala1146Thr) and c.2212-10A > G, c.3436G > A (p.Ala1146Thr) and c.2266C > T (p.Gln756*), c.1238_1239insC (p.Leu414Serfs*28) and c.3130A > G (p.Thr1044Ala). RT-PCR confirmed that the splicing variants indeed led to abnormal splicing. Missense variants p.Thr1044Ala, p.Ser1045Leu, p.Ala1146Thr, p.Arg1183Trp and c.3846+1G > A are located in Patatin-like phospholipase (Pat) domain. In conclusion, we report the phenotypes in five patients with PNPLA6 associated syndromic retinal dystrophy with variable systemic involvement and typical choroideremia-like fundus changes. Ocular manifestations may be the first and the only findings for years. All of our patients carried one severe deleterious variant (stop-gain or splicing variant) and one milder variant (missense variant). Retinal involvement was significantly correlated with severe deleterious variants and variants in Pat domain.
Collapse
Affiliation(s)
- Shijing Wu
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Zixi Sun
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Tian Zhu
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Richard G Weleber
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Paul Yang
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Xing Wei
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Mark E Pennesi
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA.
| | - Ruifang Sui
- Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
| |
Collapse
|
7
|
Richardson RJ, Fink JK, Glynn P, Hufnagel RB, Makhaeva GF, Wijeyesakere SJ. Neuropathy target esterase (NTE/PNPLA6) and organophosphorus compound-induced delayed neurotoxicity (OPIDN). ADVANCES IN NEUROTOXICOLOGY 2020; 4:1-78. [PMID: 32518884 PMCID: PMC7271139 DOI: 10.1016/bs.ant.2020.01.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Systemic inhibition of neuropathy target esterase (NTE) with certain organophosphorus (OP) compounds produces OP compound-induced delayed neurotoxicity (OPIDN), a distal degeneration of axons in the central nervous system (CNS) and peripheral nervous system (PNS), thereby providing a powerful model for studying a spectrum of neurodegenerative diseases. Axonopathies are important medical entities in their own right, but in addition, illnesses once considered primary neuronopathies are now thought to begin with axonal degeneration. These disorders include Alzheimer's disease, Parkinson's disease, and motor neuron diseases such as amyotrophic lateral sclerosis (ALS). Moreover, conditional knockout of NTE in the mouse CNS produces vacuolation and other degenerative changes in large neurons in the hippocampus, thalamus, and cerebellum, along with degeneration and swelling of axons in ascending and descending spinal cord tracts. In humans, NTE mutations cause a variety of neurodegenerative conditions resulting in a range of deficits including spastic paraplegia and blindness. Mutations in the Drosophila NTE orthologue SwissCheese (SWS) produce neurodegeneration characterized by vacuolization that can be partially rescued by expression of wild-type human NTE, suggesting a potential therapeutic approach for certain human neurological disorders. This chapter defines NTE and OPIDN, presents an overview of OP compounds, provides a rationale for NTE research, and traces the history of discovery of NTE and its relationship to OPIDN. It then briefly describes subsequent studies of NTE, including practical applications of the assay; aspects of its domain structure, subcellular localization, and tissue expression; abnormalities associated with NTE mutations, knockdown, and conventional or conditional knockout; and hypothetical models to help guide future research on elucidating the role of NTE in OPIDN.
Collapse
Affiliation(s)
- Rudy J. Richardson
- Molecular Simulations Laboratory, Department of Environmental Health Sciences, University of Michigan, Ann Arbor, MI, United States,Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States,Center for Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, United States,Michigan Institute for Computational Discovery and Engineering, University of Michigan, Ann Arbor, MI, United States,Corresponding author:
| | - John K. Fink
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States,Ann Arbor Veterans Affairs Medical Center, Ann Arbor, MI, United States
| | - Paul Glynn
- Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Robert B. Hufnagel
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, United States
| | - Galina F. Makhaeva
- Institute of Physiologically Active Compounds Russian Academy of Sciences, Chernogolovka, Russia
| | - Sanjeeva J. Wijeyesakere
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, United States
| |
Collapse
|
8
|
Characterization of the Interaction of Neuropathy Target Esterase with the Endoplasmic Reticulum and Lipid Droplets. Biomolecules 2019; 9:biom9120848. [PMID: 31835418 PMCID: PMC6995513 DOI: 10.3390/biom9120848] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/05/2019] [Accepted: 12/05/2019] [Indexed: 12/02/2022] Open
Abstract
Neuropathy target esterase (NTE) is an endoplasmic reticulum (ER)-localized phospholipase that deacylates phosphatidylcholine (PC) and lysophosphatidylcholine (LPC). Loss-of-function mutations in the human NTE gene have been associated with a spectrum of neurodegenerative disorders such as hereditary spastic paraplegia, ataxia and chorioretinal dystrophy. Despite this, little is known about structure–function relationships between NTE protein domains, enzymatic activity and the interaction with cellular organelles. In the current study we show that the C-terminal region of NTE forms a catalytically active domain that exhibits high affinity for lipid droplets (LDs), cellular storage organelles for triacylglycerol (TAG), which have been recently implicated in the progression of neurodegenerative diseases. Ectopic expression of the C domain in cultured cells decreases cellular PC, elevates TAG and induces LD clustering. LD interactions of NTE are inhibited by default by a non-enzymatic regulatory (R) region with three putative nucleotide monophosphate binding sites. Together with a N-terminal TMD the R region promotes proper distribution of the catalytic C-terminal region to the ER network. Taken together, our data indicate that NTE may exhibit dynamic interactions with the ER and LDs depending on the interplay of its functional regions. Mutations that disrupt this interplay may contribute to NTE-associated disorders by affecting NTE positioning.
Collapse
|
9
|
Faria M, Fuertes I, Prats E, Abad JL, Padrós F, Gomez-Canela C, Casas J, Estevez J, Vilanova E, Piña B, Raldúa D. Analysis of the neurotoxic effects of neuropathic organophosphorus compounds in adult zebrafish. Sci Rep 2018; 8:4844. [PMID: 29555973 PMCID: PMC5859099 DOI: 10.1038/s41598-018-22977-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/05/2018] [Indexed: 12/13/2022] Open
Abstract
Inhibition and aging of neuropathy target esterase (NTE) by exposure to neuropathic organophosphorus compounds (OPs) can result in OP-induced delayed neuropathy (OPIDN). In the present study we aimed to build a model of OPIDN in adult zebrafish. First, inhibition and aging of zebrafish NTE activity were characterized in the brain by using the prototypic neuropathic compounds cresyl saligenin phosphate (CBDP) and diisopropylphosphorofluoridate (DFP). Our results show that, as in other animal models, zebrafish NTE is inhibited and aged by both neuropathic OPs. Then, a neuropathic concentration inhibiting NTE activity by at least 70% for at least 24 h was selected for each compound to analyze changes in phosphatidylcholines (PCs), lysophosphatidylcholines (LPCs) and glycerolphosphocholine (GPC) profiles. In spite to the strong inhibition of the NTE activity found for both compounds, only a mild increase in the LPCs level was found after 48 h of the exposure to DFP, and no effect were observed by CBDP. Moreover, histopathological evaluation and motor function outcome analyses failed to find any neurological abnormalities in the exposed fish. Thus, our results strongly suggest that zebrafish is not a suitable species for the development of an experimental model of human OPIDN.
Collapse
Affiliation(s)
- Melissa Faria
- Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18, E-08034, Barcelona, Spain
| | - Inmaculada Fuertes
- Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18, E-08034, Barcelona, Spain
| | - Eva Prats
- CID-CSIC, Jordi Girona 18, E-08034, Barcelona, Spain
| | - Jose Luis Abad
- Department of Biomedicinal Chemistry, Institute for Advanced Chemistry of Catalonia, (IQAC-CSIC), Jordi Girona 18, E-08034, Barcelona, Spain
| | - Francesc Padrós
- Fish Diseases Diagnostic Service, Facultat de Veterinaria Universitat Autònoma de Barcelona, 08190, Bellaterra (Cerdanyola del Vallès), Spain
| | - Cristian Gomez-Canela
- Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18, E-08034, Barcelona, Spain
| | - Josefina Casas
- Department of Biomedicinal Chemistry, Institute for Advanced Chemistry of Catalonia, (IQAC-CSIC), Jordi Girona 18, E-08034, Barcelona, Spain
| | - Jorge Estevez
- Institute of Bioengineering, University "Miguel Hernandez" of Elche, Alicante, Spain
| | - Eugenio Vilanova
- Institute of Bioengineering, University "Miguel Hernandez" of Elche, Alicante, Spain
| | - Benjamin Piña
- Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18, E-08034, Barcelona, Spain
| | - Demetrio Raldúa
- Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Jordi Girona 18, E-08034, Barcelona, Spain.
| |
Collapse
|
10
|
Ramanadham S, Ali T, Ashley JW, Bone RN, Hancock WD, Lei X. Calcium-independent phospholipases A2 and their roles in biological processes and diseases. J Lipid Res 2015; 56:1643-68. [PMID: 26023050 DOI: 10.1194/jlr.r058701] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Indexed: 12/24/2022] Open
Abstract
Among the family of phospholipases A2 (PLA2s) are the Ca(2+)-independent PLA2s (iPLA2s) and they are designated group VI iPLA2s. In relation to secretory and cytosolic PLA2s, the iPLA2s are more recently described and details of their expression and roles in biological functions are rapidly emerging. The iPLA2s or patatin-like phospholipases (PNPLAs) are intracellular enzymes that do not require Ca(2+) for activity, and contain lipase (GXSXG) and nucleotide-binding (GXGXXG) consensus sequences. Though nine PNPLAs have been recognized, PNPLA8 (membrane-associated iPLA2γ) and PNPLA9 (cytosol-associated iPLA2β) are the most widely studied and understood. The iPLA2s manifest a variety of activities in addition to phospholipase, are ubiquitously expressed, and participate in a multitude of biological processes, including fat catabolism, cell differentiation, maintenance of mitochondrial integrity, phospholipid remodeling, cell proliferation, signal transduction, and cell death. As might be expected, increased or decreased expression of iPLA2s can have profound effects on the metabolic state, CNS function, cardiovascular performance, and cell survival; therefore, dysregulation of iPLA2s can be a critical factor in the development of many diseases. This review is aimed at providing a general framework of the current understanding of the iPLA2s and discussion of the potential mechanisms of action of the iPLA2s and related involved lipid mediators.
Collapse
Affiliation(s)
- Sasanka Ramanadham
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Tomader Ali
- Undergraduate Research Office, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Jason W Ashley
- Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104
| | - Robert N Bone
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - William D Hancock
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Xiaoyong Lei
- Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294 Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294
| |
Collapse
|
11
|
Hufnagel RB, Arno G, Hein ND, Hersheson J, Prasad M, Anderson Y, Krueger LA, Gregory LC, Stoetzel C, Jaworek TJ, Hull S, Li A, Plagnol V, Willen CM, Morgan TM, Prows CA, Hegde RS, Riazuddin S, Grabowski GA, Richardson RJ, Dieterich K, Huang T, Revesz T, Martinez-Barbera JP, Sisk RA, Jefferies C, Houlden H, Dattani MT, Fink JK, Dollfus H, Moore AT, Ahmed ZM. Neuropathy target esterase impairments cause Oliver-McFarlane and Laurence-Moon syndromes. J Med Genet 2014; 52:85-94. [PMID: 25480986 DOI: 10.1136/jmedgenet-2014-102856] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Oliver-McFarlane syndrome is characterised by trichomegaly, congenital hypopituitarism and retinal degeneration with choroidal atrophy. Laurence-Moon syndrome presents similarly, though with progressive spinocerebellar ataxia and spastic paraplegia and without trichomegaly. Both recessively inherited disorders have no known genetic cause. METHODS Whole-exome sequencing was performed to identify the genetic causes of these disorders. Mutations were functionally validated in zebrafish pnpla6 morphants. Embryonic expression was evaluated via in situ hybridisation in human embryonic sections. Human neurohistopathology was performed to characterise cerebellar degeneration. Enzymatic activities were measured in patient-derived fibroblast cell lines. RESULTS Eight mutations in six families with Oliver-McFarlane or Laurence-Moon syndrome were identified in the PNPLA6 gene, which encodes neuropathy target esterase (NTE). PNPLA6 expression was found in the developing human eye, pituitary and brain. In zebrafish, the pnpla6 curly-tailed morphant phenotype was fully rescued by wild-type human PNPLA6 mRNA and not by mutation-harbouring mRNAs. NTE enzymatic activity was significantly reduced in fibroblast cells derived from individuals with Oliver-McFarlane syndrome. Intriguingly, adult brain histology from a patient with highly overlapping features of Oliver-McFarlane and Laurence-Moon syndromes revealed extensive cerebellar degeneration and atrophy. CONCLUSIONS Previously, PNPLA6 mutations have been associated with spastic paraplegia type 39, Gordon-Holmes syndrome and Boucher-Neuhäuser syndromes. Discovery of these additional PNPLA6-opathies further elucidates a spectrum of neurodevelopmental and neurodegenerative disorders associated with NTE impairment and suggests a unifying mechanism with diagnostic and prognostic importance.
Collapse
Affiliation(s)
- Robert B Hufnagel
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - Gavin Arno
- UCL Institute of Ophthalmology and Moorfields Eye Hospital, London, UK
| | - Nichole D Hein
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Joshua Hersheson
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Megana Prasad
- Laboratoire de génétique Médicale, Université de Strasbourg, FMTS, Strasbourg, France
| | - Yvonne Anderson
- Department of Paediatrics, Taranaki Base Hospital, New Plymouth, New Zealand Liggins Institute, University of Auckland, Auckland, New Zealand
| | - Laura A Krueger
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - Louise C Gregory
- Developmental Endocrinology Research Group, Genetics and Epigenetics in Health and Disease Section, Genetics and Genomic Medicine Programme, University College London Institute of Child Health, London, UK
| | - Corinne Stoetzel
- Laboratoire de génétique Médicale, Université de Strasbourg, FMTS, Strasbourg, France
| | - Thomas J Jaworek
- Department of Otorhinolaryngology, University of Maryland, Baltimore, Maryland, USA
| | - Sarah Hull
- UCL Institute of Ophthalmology and Moorfields Eye Hospital, London, UK
| | - Abi Li
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Vincent Plagnol
- Department of Statistical Genetics, University College London, London, UK
| | - Christi M Willen
- Department of Pediatric Ophthalmology, University of Kentucky, Lexington, Kentucky, USA
| | - Thomas M Morgan
- Department of Pediatrics, Vanderbilt University, Nashville, Tennessee, USA
| | - Cynthia A Prows
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - Rashmi S Hegde
- Developmental Biology, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - Saima Riazuddin
- Department of Otorhinolaryngology, University of Maryland, Baltimore, Maryland, USA
| | - Gregory A Grabowski
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - Rudy J Richardson
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan, USA
| | - Klaus Dieterich
- Département de Génétique et Procréation, Hôpital Couple Enfant, CHU Grenoble and Grenoble Institut des Neurosciences, Equipe Muscle et Pathologie, Grenoble, France
| | - Taosheng Huang
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - Tamas Revesz
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - J P Martinez-Barbera
- Developmental Endocrinology Research Group, Genetics and Epigenetics in Health and Disease Section, Genetics and Genomic Medicine Programme, University College London Institute of Child Health, London, UK
| | - Robert A Sisk
- Division of Pediatric Ophthalmology, Cincinnati Children's Hospital, Cincinnati, Ohio, USA Cincinnati Eye Institute, Cincinnati, Ohio, USA
| | - Craig Jefferies
- Department of Paediatric Endocrinology, Starship Children's Hospital, Auckland, New Zealand
| | - Henry Houlden
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Mehul T Dattani
- Developmental Endocrinology Research Group, Genetics and Epigenetics in Health and Disease Section, Genetics and Genomic Medicine Programme, University College London Institute of Child Health, London, UK
| | - John K Fink
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Helene Dollfus
- Laboratoire de génétique Médicale, Université de Strasbourg, FMTS, Strasbourg, France Centre de référence pour les Affections Rares Ophtalmologiques CARGO, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Anthony T Moore
- UCL Institute of Ophthalmology and Moorfields Eye Hospital, London, UK
| | - Zubair M Ahmed
- Department of Otorhinolaryngology, University of Maryland, Baltimore, Maryland, USA
| |
Collapse
|
12
|
Lo Giudice T, Lombardi F, Santorelli FM, Kawarai T, Orlacchio A. Hereditary spastic paraplegia: clinical-genetic characteristics and evolving molecular mechanisms. Exp Neurol 2014; 261:518-39. [PMID: 24954637 DOI: 10.1016/j.expneurol.2014.06.011] [Citation(s) in RCA: 244] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Revised: 06/07/2014] [Accepted: 06/12/2014] [Indexed: 12/12/2022]
Abstract
Hereditary spastic paraplegia (HSP) is a group of clinically and genetically heterogeneous neurological disorders characterized by pathophysiologic hallmark of length-dependent distal axonal degeneration of the corticospinal tracts. The prominent features of this pathological condition are progressive spasticity and weakness of the lower limbs. To date, 72 spastic gait disease-loci and 55 spastic paraplegia genes (SPGs) have been identified. All modes of inheritance (autosomal dominant, autosomal recessive, and X-linked) have been described. Recently, a late onset spastic gait disorder with maternal trait of inheritance has been reported, as well as mutations in genes not yet classified as spastic gait disease. Several cellular processes are involved in its pathogenesis, such as membrane and axonal transport, endoplasmic reticulum membrane modeling and shaping, mitochondrial function, DNA repair, autophagy, and abnormalities in lipid metabolism and myelination processes. Moreover, recent evidences have been found about the impairment of endosome membrane trafficking in vesicle formation and about the involvement of oxidative stress and mtDNA polymorphisms in the onset of the disease. Interactome networks have been postulated by bioinformatics and biological analyses of spastic paraplegia genes, which would contribute to the development of new therapeutic approaches.
Collapse
Affiliation(s)
- Temistocle Lo Giudice
- Laboratorio di Neurogenetica, Centro Europeo di Ricerca sul Cervello (CERC) - Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Santa Lucia, Rome, Italy; Dipartimento di Medicina dei Sistemi, Università di Roma "Tor Vergata", Rome, Italy
| | - Federica Lombardi
- Laboratorio di Neurogenetica, Centro Europeo di Ricerca sul Cervello (CERC) - Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Santa Lucia, Rome, Italy
| | - Filippo Maria Santorelli
- Unità Operativa Complessa di Medicina Molecolare, Neurogenetica e Malattie Neurodegenerative, IRCCS Stella Maris, Pisa, Italy
| | - Toshitaka Kawarai
- Department of Clinical Neuroscience, Institute of Health Biosciences, Graduate School of Medicine, University of Tokushima, Tokushima, Japan
| | - Antonio Orlacchio
- Laboratorio di Neurogenetica, Centro Europeo di Ricerca sul Cervello (CERC) - Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Santa Lucia, Rome, Italy; Dipartimento di Medicina dei Sistemi, Università di Roma "Tor Vergata", Rome, Italy.
| |
Collapse
|
13
|
Functional pathways altered after silencing Pnpla6 (the codifying gene of neuropathy target esterase) in mouse embryonic stem cells under differentiation. In Vitro Cell Dev Biol Anim 2013; 50:261-73. [PMID: 24142151 DOI: 10.1007/s11626-013-9691-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Accepted: 09/10/2013] [Indexed: 12/15/2022]
Abstract
Neuropathy target esterase (NTE) is involved in several disorders in adult organisms and embryos. A relationship between NTE and nervous system integrity and maintenance in adult systems has been suggested. NTE-related motor neuron disease is associated with the expression of a mutant form of NTE and the inhibition and further modification of NTE by organophosphorus compounds is the trigger of a delayed neurodegenerative neuropathy. Homozygotic NTE knockout mice embryos are not viable, while heterozygotic NTE knockout mice embryos yields mice with neurological disorders, which suggest that this protein plays a critical role in embryonic development. The present study used D3 mouse embryonic stem cells with the aim of gaining mechanistic insights on the role of Pnpla6 (NTE gene encoding) in the developmental process. D3 cells were silenced by lipofectamine transfection with a specific interference RNA for Pnpla6. Silencing Pnpla6 in D3 monolayer cultures reduced NTE enzymatic activity to 50% 20 h post-treatment, while the maximum loss of Pnpla6 expression reached 80% 48 h postsilencing. Pnpla6 was silenced in embryoid bodies and 545 genes were differentially expressed regarding the control 96 h after silencing, which revealed alterations in multiple genetic pathways, such as cell motion and cell migration, vesicle regulation, and cell adhesion. These findings also allow considering that these altered pathways would impair the formation of respiratory, neural, and vascular tubes causing the deficiencies observed in the in vivo development of nervous and vascular systems. Our findings, therefore, support the previous observations made in vivo concerning lack of viability of mice embryos not expressing NTE and help to understand the biology of several neurological and developmental disorders in which NTE is involved.
Collapse
|
14
|
Richardson RJ, Hein ND, Wijeyesakere SJ, Fink JK, Makhaeva GF. Neuropathy target esterase (NTE): overview and future. Chem Biol Interact 2012; 203:238-44. [PMID: 23220002 DOI: 10.1016/j.cbi.2012.10.024] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/22/2012] [Accepted: 10/30/2012] [Indexed: 11/29/2022]
Abstract
Neuropathy target esterase (NTE) was discovered by M.K. Johnson in his quest for the entity responsible for the striking and mysterious paralysis brought about by certain organophosphorus (OP) esters. His pioneering work on OP neuropathy led to the view that the biochemical lesion consisted of NTE that had undergone OP inhibition and aging. Indeed, nonaging NTE inhibitors failed to produce disease but protected against neuropathy from subsequently administered aging inhibitors. Thus, inhibition of NTE activity was not the culprit; rather, formation of an abnormal protein was the agent of the disorder. More recently, however, Paul Glynn and colleagues showed that whereas conventional knockout of the NTE gene was embryonic lethal, conditional knockout of central nervous system NTE produced neurodegeneration, suggesting to these authors that the absence of NTE rather than its presence in some altered form caused disease. We now know that NTE is the 6th member of a 9-protein family called patatin-like phospholipase domain-containing proteins, PNPLA1-9. Mutations in the catalytic domain of NTE (PNPLA6) are associated with a slowly developing disease akin to OP neuropathy and hereditary spastic paraplegia called NTE-related motor neuron disorder (NTE-MND). Furthermore, the NTE protein from affected individuals has altered enzymological characteristics. Moreover, closely related PNPLA7 is regulated by insulin and glucose. These seemingly disparate findings are not necessarily mutually exclusive, but we need to reconcile recent genetic findings with the historical body of toxicological data indicating that inhibition and aging of NTE are both necessary in order to produce neuropathy from exposure to certain OP compounds. Solving this mystery will be satisfying in itself, but it is also an enterprise likely to pay dividends by enhancing our understanding of the physiological and pathogenic roles of the PNPLA family of proteins in neurological health and disease, including a potential role for NTE in diabetic neuropathy.
Collapse
Affiliation(s)
- Rudy J Richardson
- Toxicology Program, University of Michigan, Ann Arbor, MI 48109-2029, USA.
| | | | | | | | | |
Collapse
|
15
|
Song Y, Wang M, Mao F, Shao M, Zhao B, Song Z, Shao C, Gong Y. Knockdown of Pnpla6 protein results in motor neuron defects in zebrafish. Dis Model Mech 2012; 6:404-13. [PMID: 22996643 PMCID: PMC3597022 DOI: 10.1242/dmm.009688] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Mutations in patatin-like phospholipase domain containing 6 (PNPLA6), also known as neuropathy target esterase (NTE) or SPG39, cause hereditary spastic paraplegia (HSP). Although studies on animal models, including mice and Drosophila, have extended our understanding of PNPLA6, its roles in neural development and in HSP are not clearly understood. Here, we describe the generation of a vertebrate model of PNPLA6 insufficiency using morpholino oligonucleotide knockdown in zebrafish (Danio rerio). Pnpla6 knockdown resulted in developmental abnormalities and motor neuron defects, including axon truncation and branching. The phenotypes in pnpla6 knockdown morphants were rescued by the introduction of wild-type, but not mutant, human PNPLA6 mRNA. Our results also revealed the involvement of BMP signaling in pnpla6 knockdown phenotypes. Taken together, these results demonstrate an important role of PNPLA6 in motor neuron development and implicate overexpression of BMP signaling as a possible mechanism underlying the developmental defects in pnpla6 morphants.
Collapse
Affiliation(s)
- Yang Song
- Institute of Medical Genetics and Key Laboratory for Experimental Teratology of Ministry of Education, School of Medicine, Shandong University, Jinan 250012 Shandong, China
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Finsterer J, Löscher W, Quasthoff S, Wanschitz J, Auer-Grumbach M, Stevanin G. Hereditary spastic paraplegias with autosomal dominant, recessive, X-linked, or maternal trait of inheritance. J Neurol Sci 2012; 318:1-18. [PMID: 22554690 DOI: 10.1016/j.jns.2012.03.025] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 03/25/2012] [Accepted: 03/29/2012] [Indexed: 12/12/2022]
Abstract
Hereditary spastic paraplegia (SPG) is a clinically and genetically heterogeneous group of neurodegenerative disorders that are clinically characterised by progressive spasticity and weakness of the lower-limbs (pure SPG) and, majoritorian, additional more extensive neurological or non-neurological manifestations (complex or complicated SPG). Pure SPG is characterised by progressive spasticity and weakness of the lower-limbs, and occasionally sensory disturbances or bladder dysfunction. Complex SPGs additionally include cognitive impairment, dementia, epilepsy, extrapyramidal disturbances, cerebellar involvement, retinopathy, optic atrophy, deafness, polyneuropathy, or skin lesions in the absence of coexisting disorders. Nineteen SPGs follow an autosomal-dominant (AD-SPG), 27 an autosomal-recessive (AR-SPG), 5 X-linked (XL-SPG), and one a maternal trait of inheritance. SPGs are due to mutations in genes encoding for proteins involved in the maintenance of corticospinal tract neurons. Among the AD-SPGs, 40-45% of patients carry mutations in the SPAST-gene (SPG4) and 10% in the ATL1-gene (SPG3), while the other 9 genes are more rarely involved (NIPA1 (SPG6), KIAA0196 (SPG8), KIF5A (SPG10), RNT2 (SPG12), SPGD1 (SPG13), BSCL2 (SPG17), REEP1 (SPG31), ZFYVE27 (SPG33, debated), and SLC33A1 (SPG42, debated)). Among the AR-SPGs, ~20% of the patients carry mutations in the KIAA1840 (SPG11) gene whereas the 15 other genes are rarely mutated and account for SPGs in single families yet (CYP7B1 (SPG5), SPG7 (SPG7), ZFYVE26 (SPG15), ERLIN2 (SPG18), SPG20 (SPG20), ACP33 (SPG21), KIF1A (SPG30), FA2H (SPG35), NTE (SPG39), GJA12/GJC2 (SPG44), KIAA0415 (SPG48) and 4 genes encoding for the AP4-complex (SPG47)). Among the XL-SPGs, 3 causative genes have been identified (L1CAM (SPG1), PLP1 (SPG2), and SLC16A2 (SPG22)). The diagnosis of SPGs is based on clinical, instrumental and genetic investigations. Treatment is exclusively symptomatic.
Collapse
|
17
|
Neurodegenerations Induced by Organophosphorous Compounds. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 724:189-204. [DOI: 10.1007/978-1-4614-0653-2_15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
|
18
|
Current world literature. Curr Opin Neurol 2011; 24:511-6. [PMID: 21900773 DOI: 10.1097/wco.0b013e32834be5c1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
19
|
Rainier S, Albers JW, Dyck PJ, Eldevik OP, Wilcock S, Richardson RJ, Fink JK. Motor neuron disease due to neuropathy target esterase gene mutation: clinical features of the index families. Muscle Nerve 2011; 43:19-25. [PMID: 21171093 DOI: 10.1002/mus.21777] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Recently, we reported that mutations in the neuropathy target esterase (NTE) gene cause autosomal recessive motor neuron disease (NTE-MND). We describe clinical, neurophysiologic, and neuroimaging features of affected subjects in the index families. NTE-MND subjects exhibited progressive lower extremity spastic weakness that began in childhood and was later associated with atrophy of distal leg and intrinsic hand muscles. NTE-MND resembles Troyer syndrome, except that short stature, cognitive impairment, and dysmorphic features, which often accompany Troyer syndrome, are not features of NTE-MND. Early onset, symmetry, and slow progression distinguish NTE-MND from typical amyotrophic lateral sclerosis. NTE is implicated in organophosphorus compound-induced delayed neurotoxicity (OPIDN). NTE-MND patients have upper and lower motor neuron deficits that are similar to OPIDN. Motor neuron degeneration in subjects with NTE mutations supports the role of NTE and its biochemical cascade in the molecular pathogenesis of OPIDN and possibly other degenerative neurologic disorders.
Collapse
Affiliation(s)
- Shirley Rainier
- Department of Neurology, University of Michigan, 5013 BSRB, 109 Zina Pitcher Place, Ann Arbor, Michigan 48109, USA
| | | | | | | | | | | | | |
Collapse
|
20
|
Hein ND, Rainier SR, Richardson RJ, Fink JK. Motor neuron disease due to neuropathy target esterase mutation: enzyme analysis of fibroblasts from human subjects yields insights into pathogenesis. Toxicol Lett 2010; 199:1-5. [PMID: 20603202 DOI: 10.1016/j.toxlet.2010.06.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 06/24/2010] [Accepted: 06/25/2010] [Indexed: 11/25/2022]
Abstract
Recently, we identified neuropathy target esterase (NTE) mutation as the cause of an autosomal recessive motor neuron disease (NTE-MND). Subsequently, we showed that NTE-MND mutations reduced specific activity (SA) and altered inhibitory kinetics of NTE catalytic domain constructs. Recent preliminary results showed that NTE is expressed in cultured human skin fibroblasts, and others have used mutant forms of neuronal proteins expressed in fibroblasts as biomarkers of neurogenetic diseases. Therefore, the present study was carried out to test the hypothesis that NTE in cultured skin fibroblasts from NTE-MND subjects also exhibit altered enzymological properties assessed by SA and IC(50) values of mipafox (MIP) and chlorpyrifos oxon (CPO). NTE SA was reduced to 65% of control (wild-type NTE from commercially obtained fibroblasts) in homozygous M1012V fibroblasts and 59-61% of control in compound heterozygous R890H/c2946_2947InsCAGC fibroblasts. MIP IC(50) values were unaffected by the NTE mutations, but the CPO IC(50) increased 4.5-fold in homozygous M1012V fibroblasts. Interestingly, markedly reduced NTE SAs (40-43% of control) were observed in fibroblasts from asymptomatic subjects heterozygous for NTE insertion c2946_2947InsCAGC. This insertion is predicted to produce truncated NTE missing the last 235 residues of its catalytic domain. These observations confirm that NTE-MND mutations reduce NTE SA in vitro. Moreover, to the extent observations made in cultured fibroblasts may be generalized to events in the nervous system, lack of correlation between reduced fibroblast NTE SA and the occurrence of NTE-MND in NTE insertion mutation heterozygotes indicates that reduction of NTE SA alone is insufficient to cause MND.
Collapse
Affiliation(s)
- Nichole D Hein
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | | | | | | |
Collapse
|