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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.
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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
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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.
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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
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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.
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Melentev PA, Ryabova EV, Sarantseva SV. A Private History of Neurogenetics: The swiss cheese Gene and Its Orthologs. RUSS J GENET+ 2021. [DOI: 10.1134/s1022795421090076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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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.
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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.
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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.
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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
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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.
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Sunderhaus ER, Law AD, Kretzschmar D. Disease-Associated PNPLA6 Mutations Maintain Partial Functions When Analyzed in Drosophila. Front Neurosci 2019; 13:1207. [PMID: 31780887 PMCID: PMC6852622 DOI: 10.3389/fnins.2019.01207] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 10/25/2019] [Indexed: 12/22/2022] Open
Abstract
Mutations in patatin-like phospholipase domain-containing protein 6 (PNPLA6) have been linked with a number of inherited diseases with clinical symptoms that include spastic paraplegia, ataxia, and chorioretinal dystrophy. PNPLA6 is an evolutionary conserved protein whose ortholog in Drosophila is Swiss-Cheese (SWS). Both proteins are phospholipases hydrolyzing lysophosphatidylcholine (LPC) and phosphatidylcholine (PC). Consequently, loss of SWS/PNPLA6 in flies and mice increases both lipids and leads to locomotion deficits and neurodegeneration. PNPLA6 knock-out mice are embryonic lethal, and a mutation creating an early stop codon in human PNPLA6 has only been identified in compound heterozygote patients. In contrast, disease-causing point mutations are found in homozygous patients, with some localized in the phospholipase domain while others are in a region that contains several cNMP binding sites. To investigate how different mutations affect the function of PNPLA6 in an in vivo model, we expressed them in the Drosophila sws1 null mutant. Expressing wild-type PNPLA6 suppressed the locomotion and degenerative phenotypes in sws 1 and restored lipid levels, confirming that the human protein can replace fly SWS. In contrast, none of the mutant proteins restored lipid levels, although they suppressed the behavioral and degenerative phenotypes, at least in early stages. These results show that these mutant forms of PNPLA6 retain some biological function, indicating that disruption of lipid homeostasis is only part of the pathogenic mechanism. Furthermore, our finding that mutations in the cNMP binding sites prevented the restoration of normal lipid levels supports previous evidence that cNMP regulates the phospholipase activity of PNPLA6.
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Affiliation(s)
| | | | - Doris Kretzschmar
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, United States
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9
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Sánchez-Santed F, Colomina MT, Herrero Hernández E. Organophosphate pesticide exposure and neurodegeneration. Cortex 2016; 74:417-26. [DOI: 10.1016/j.cortex.2015.10.003] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Revised: 09/28/2015] [Accepted: 10/05/2015] [Indexed: 12/11/2022]
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10
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Sujkowski A, Rainier S, Fink JK, Wessells RJ. Delayed Induction of Human NTE (PNPLA6) Rescues Neurodegeneration and Mobility Defects of Drosophila swiss cheese (sws) Mutants. PLoS One 2015; 10:e0145356. [PMID: 26671664 PMCID: PMC4684404 DOI: 10.1371/journal.pone.0145356] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 12/02/2015] [Indexed: 12/04/2022] Open
Abstract
Human PNPLA6 gene encodes Neuropathy Target Esterase protein (NTE). PNPLA6 gene mutations cause hereditary spastic paraplegia (SPG39 HSP), Gordon-Holmes syndrome, Boucher-Neuhäuser syndromes, Laurence-Moon syndrome, and Oliver-McFarlane syndrome. Mutations in the Drosophila NTE homolog swiss cheese (sws) cause early-onset, progressive behavioral defects and neurodegeneration characterized by vacuole formation. We investigated sws5 flies and show for the first time that this allele causes progressive vacuolar formation in the brain and progressive deterioration of negative geotaxis speed and endurance. We demonstrate that inducible, neuron-specific expression of full-length human wildtype NTE reduces vacuole formation and substantially rescues mobility. Indeed, neuron-specific expression of wildtype human NTE is capable of rescuing mobility defects after 10 days of adult life at 29°C, when significant degeneration has already occurred, and significantly extends longevity of mutants at 25°C. These results raise the exciting possibility that late induction of NTE function may reduce or ameliorate neurodegeneration in humans even after symptoms begin. In addition, these results highlight the utility of negative geotaxis endurance as a new assay for longitudinal tracking of degenerative phenotypes in Drosophila.
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Affiliation(s)
- Alyson Sujkowski
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Shirley Rainier
- Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - John K. Fink
- Department of Neurology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Geriatric Research Education and Clinical Center, Ann Arbor Veterans Affairs Medical Center, Ann Arbor, Michigan, United States of America
- * E-mail: (RJW); (JKF)
| | - Robert J. Wessells
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- * E-mail: (RJW); (JKF)
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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.
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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
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12
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Kmoch S, Majewski J, Ramamurthy V, Cao S, Fahiminiya S, Ren H, MacDonald IM, Lopez I, Sun V, Keser V, Khan A, Stránecký V, Hartmannová H, Přistoupilová A, Hodaňová K, Piherová L, Kuchař L, Baxová A, Chen R, Barsottini OGP, Pyle A, Griffin H, Splitt M, Sallum J, Tolmie JL, Sampson JR, Chinnery P, Banin E, Sharon D, Dutta S, Grebler R, Helfrich-Foerster C, Pedroso JL, Kretzschmar D, Cayouette M, Koenekoop RK. Mutations in PNPLA6 are linked to photoreceptor degeneration and various forms of childhood blindness. Nat Commun 2015; 6:5614. [PMID: 25574898 DOI: 10.1038/ncomms6614] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 10/21/2014] [Indexed: 11/09/2022] Open
Abstract
Blindness due to retinal degeneration affects millions of people worldwide, but many disease-causing mutations remain unknown. PNPLA6 encodes the patatin-like phospholipase domain containing protein 6, also known as neuropathy target esterase (NTE), which is the target of toxic organophosphates that induce human paralysis due to severe axonopathy of large neurons. Mutations in PNPLA6 also cause human spastic paraplegia characterized by motor neuron degeneration. Here we identify PNPLA6 mutations in childhood blindness in seven families with retinal degeneration, including Leber congenital amaurosis and Oliver McFarlane syndrome. PNPLA6 localizes mostly at the inner segment plasma membrane in photoreceptors and mutations in Drosophila PNPLA6 lead to photoreceptor cell death. We also report that lysophosphatidylcholine and lysophosphatidic acid levels are elevated in mutant Drosophila. These findings show a role for PNPLA6 in photoreceptor survival and identify phospholipid metabolism as a potential therapeutic target for some forms of blindness.
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Affiliation(s)
- S Kmoch
- First Faculty of Medicine, Institute for Inherited Metabolic Disorders, Charles University in Prague, 120 00 Prague 2, Czech Republic
| | - J Majewski
- Faculty of Medicine, Department of Human Genetics, McGill University and Genome Quebec Innovation Center, Montreal, Quebec, Canada H3A 0G1
| | - V Ramamurthy
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), 110, Ave des Pins Ouest, Montreal, Quebec, Canada H2W 1R7
| | - S Cao
- 1] McGill University, 845 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0G4 [2] McGill Ocular Genetics Laboratory; Departments of Paediatric Surgery, Human Genetics and Ophthalmology, Montreal Children's Hospital, McGill University Health Centre, 2300 Tupper, Montreal, Quebec, Canada H3H 1P3
| | - S Fahiminiya
- Faculty of Medicine, Department of Human Genetics, McGill University and Genome Quebec Innovation Center, Montreal, Quebec, Canada H3A 0G1
| | - H Ren
- 1] McGill University, 845 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0G4 [2] McGill Ocular Genetics Laboratory; Departments of Paediatric Surgery, Human Genetics and Ophthalmology, Montreal Children's Hospital, McGill University Health Centre, 2300 Tupper, Montreal, Quebec, Canada H3H 1P3
| | - I M MacDonald
- Department of Ophthalmology and Visual Sciences, University of Alberta/Royal Alexandra Hospital, 10240 Kingsway Avenue, Edmonton, Alberta, Canada AB T5H 3V9
| | - I Lopez
- 1] McGill University, 845 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0G4 [2] McGill Ocular Genetics Laboratory; Departments of Paediatric Surgery, Human Genetics and Ophthalmology, Montreal Children's Hospital, McGill University Health Centre, 2300 Tupper, Montreal, Quebec, Canada H3H 1P3
| | - V Sun
- 1] McGill University, 845 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0G4 [2] McGill Ocular Genetics Laboratory; Departments of Paediatric Surgery, Human Genetics and Ophthalmology, Montreal Children's Hospital, McGill University Health Centre, 2300 Tupper, Montreal, Quebec, Canada H3H 1P3
| | - V Keser
- 1] McGill University, 845 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0G4 [2] McGill Ocular Genetics Laboratory; Departments of Paediatric Surgery, Human Genetics and Ophthalmology, Montreal Children's Hospital, McGill University Health Centre, 2300 Tupper, Montreal, Quebec, Canada H3H 1P3
| | - A Khan
- 1] McGill University, 845 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0G4 [2] McGill Ocular Genetics Laboratory; Departments of Paediatric Surgery, Human Genetics and Ophthalmology, Montreal Children's Hospital, McGill University Health Centre, 2300 Tupper, Montreal, Quebec, Canada H3H 1P3
| | - V Stránecký
- First Faculty of Medicine, Institute for Inherited Metabolic Disorders, Charles University in Prague, 120 00 Prague 2, Czech Republic
| | - H Hartmannová
- First Faculty of Medicine, Institute for Inherited Metabolic Disorders, Charles University in Prague, 120 00 Prague 2, Czech Republic
| | - A Přistoupilová
- First Faculty of Medicine, Institute for Inherited Metabolic Disorders, Charles University in Prague, 120 00 Prague 2, Czech Republic
| | - K Hodaňová
- First Faculty of Medicine, Institute for Inherited Metabolic Disorders, Charles University in Prague, 120 00 Prague 2, Czech Republic
| | - L Piherová
- First Faculty of Medicine, Institute for Inherited Metabolic Disorders, Charles University in Prague, 120 00 Prague 2, Czech Republic
| | - L Kuchař
- First Faculty of Medicine, Institute for Inherited Metabolic Disorders, Charles University in Prague, 120 00 Prague 2, Czech Republic
| | - A Baxová
- First Faculty of Medicine, Institute of Biology and Medical Genetics, Charles University in Prague, 120 00 Prague 2, Czech Republic
| | - R Chen
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
| | - O G P Barsottini
- Division of General Neurology and Ataxia Unit, Department of Neurology, Universidade Federal de São Paulo, Sao Paulo 04021-001, Brazil
| | - A Pyle
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - H Griffin
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - M Splitt
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - J Sallum
- Department of Ophthalmology, Universidade Federal de São Paulo, Sao Paulo 04021-001, Brazil
| | - J L Tolmie
- Department of Clinical Genetics, Southern General Hospital, Glasgow G51 4TF, UK
| | - J R Sampson
- Institute of Medical Genetics, Cardiff University School of Medicine, Cardiff CF14 4XN, UK
| | - P Chinnery
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | | | - E Banin
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - D Sharon
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - S Dutta
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - R Grebler
- Lehrstuhl fuer Neurobiology und Genetik, Universitaet Wuerzburg, 97074 Wuerzburg, Germany
| | - C Helfrich-Foerster
- Lehrstuhl fuer Neurobiology und Genetik, Universitaet Wuerzburg, 97074 Wuerzburg, Germany
| | - J L Pedroso
- Division of General Neurology and Ataxia Unit, Department of Neurology, Universidade Federal de São Paulo, Sao Paulo 04021-001, Brazil
| | - D Kretzschmar
- Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - M Cayouette
- 1] Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), 110, Ave des Pins Ouest, Montreal, Quebec, Canada H2W 1R7 [2] Departement de Médecine, Université de Montréal, Montreal, Quebec, Canada H3T 1P1 [3] Division of Experimental Medicine, Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada H3A 2B2
| | - R K Koenekoop
- 1] McGill University, 845 Sherbrooke Street West, Montreal, Quebec, Canada H3A 0G4 [2] McGill Ocular Genetics Laboratory; Departments of Paediatric Surgery, Human Genetics and Ophthalmology, Montreal Children's Hospital, McGill University Health Centre, 2300 Tupper, Montreal, Quebec, Canada H3H 1P3
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13
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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.
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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
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14
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Matsuzaka Y, Ohkubo T, Kikuti YY, Mizutani A, Tsuda M, Aoyama Y, Kakuta K, Oka A, Inoko H, Sakabe K, Ishikawa S, Kulski JK, Kimura M. Association of sick building syndrome with neuropathy target esterase (NTE) activity in Japanese. ENVIRONMENTAL TOXICOLOGY 2014; 29:1217-1226. [PMID: 23418070 DOI: 10.1002/tox.21839] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 12/10/2012] [Indexed: 06/01/2023]
Abstract
Sick building syndrome (SBS) is a set of several clinically recognizable symptoms reported by occupants of a building without a clear cause. Neuropathy target esterase (NTE) is a membrane bound serine esterase and its reaction with organophosphates (OPs) can lead to OP-induced delayed neuropathy (OPIDN) and nerve axon degeneration. The aim of our study was to determine whether there was a difference in NTE activity in the peripheral blood mononuclear cells (PBMCs) of Japanese patients with SBS and healthy controls and whether PNPLA6 (alias NTE) gene polymorphisms were associated with SBS. We found that the enzymatic activity of NTE was significantly higher (P < 0.0005) in SBS patients compared with controls. Moreover, population with an AA genotype of a single nucleotide polymorphism (SNP), rs480208, in intron 21 of the PNPLA6 gene strongly reduced the activity of NTE. Fifty-eight SNP markers within the PNPLA6 gene were tested for association in a case-control study of 188 affected individuals and 401 age-matched controls. Only one SNP, rs480208, was statistically different in genotype distribution (P = 0.005) and allele frequency (P = 0.006) between the cases and controls (uncorrected for testing multiple SNP sites), but these were not significant by multiple corrections. The findings of the association between the enzymatic activity of NTE and SBS in Japanese show for the first time that NTE activity might be involved with SBS.
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Affiliation(s)
- Yasunari Matsuzaka
- Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Bohseidai, Isehara, Kanagawa, Japan
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15
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Organophosphate-induced changes in the PKA regulatory function of Swiss Cheese/NTE lead to behavioral deficits and neurodegeneration. PLoS One 2014; 9:e87526. [PMID: 24558370 PMCID: PMC3928115 DOI: 10.1371/journal.pone.0087526] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 12/31/2013] [Indexed: 12/02/2022] Open
Abstract
Organophosphate-induced delayed neuropathy (OPIDN) is a Wallerian-type axonopathy that occurs weeks after exposure to certain organophosphates (OPs). OPs have been shown to bind to Neuropathy Target Esterase (NTE), thereby inhibiting its enzymatic activity. However, only OPs that also induce the so-called aging reaction cause OPIDN. This reaction results in the release and possible transfer of a side group from the bound OP to NTE and it has been suggested that this induces an unknown toxic function of NTE. To further investigate the mechanisms of aging OPs, we used Drosophila, which expresses a functionally conserved orthologue of NTE named Swiss Cheese (SWS). Treating flies with the organophosporous compound tri-ortho-cresyl phosphate (TOCP) resulted in behavioral deficits and neurodegeneration two weeks after exposure, symptoms similar to the delayed effects observed in other models. In addition, we found that primary neurons showed signs of axonal degeneration within an hour after treatment. Surprisingly, increasing the levels of SWS, and thereby its enzymatic activity after exposure, did not ameliorate these phenotypes. In contrast, reducing SWS levels protected from TOCP-induced degeneration and behavioral deficits but did not affect the axonopathy observed in cell culture. Besides its enzymatic activity as a phospholipase, SWS also acts as regulatory PKA subunit, binding and inhibiting the C3 catalytic subunit. Measuring PKA activity in TOCP treated flies revealed a significant decrease that was also confirmed in treated rat hippocampal neurons. Flies expressing additional PKA-C3 were protected from the behavioral and degenerative phenotypes caused by TOCP exposure whereas primary neurons were not. In addition, knocking-down PKA-C3 caused similar behavioral and degenerative phenotypes as TOCP treatment. We therefore propose a model in which OP-modified SWS cannot release PKA-C3 and that the resulting loss of PKA-C3 activity plays a crucial role in developing the delayed symptoms of OPIDN but not in the acute toxicity.
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16
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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.
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Affiliation(s)
- Rudy J Richardson
- Toxicology Program, University of Michigan, Ann Arbor, MI 48109-2029, USA.
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17
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Glynn P. Neuronal phospholipid deacylation is essential for axonal and synaptic integrity. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:633-41. [PMID: 22903185 DOI: 10.1016/j.bbalip.2012.07.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 07/20/2012] [Accepted: 07/31/2012] [Indexed: 12/24/2022]
Abstract
Recessively-inherited deficiency in the catalytic activity of calcium-independent phospholipase A2-beta (iPLA2β) and neuropathy target esterase (NTE) causes infantile neuroaxonal dystrophy and hereditary spastic paraplegia, respectively. Thus, these two related phospholipases have non-redundant functions that are essential for structural integrity of synapses and axons. Both enzymes are expressed in essentially all neurons and also have independent roles in glia. iPLA2β liberates sn-2 fatty acid and lysophospholipids from diacyl-phospholipids. Ca(2+)-calmodulin tonically-inhibits iPLA2β, but this can be alleviated by oleoyl-CoA. Together with fatty acyl-CoA-mediated conversion of lysophospholipid to diacyl-phospholipid this may regulate sn-2 fatty acyl composition of phospholipids. In the nervous system, iPLA2β is especially important for the turnover of polyunsaturated fatty acid-associated phospholipid at synapses. More information is required on the interplay between iPLA2β and iPLA2-gamma in deacylation of neuronal mitochondrial phospholipids. NTE reduces levels of phosphatidylcholine (PtdCho) by degrading it to glycerophosphocholine and two free fatty acids. The substrate for NTE may be nascent PtdCho complexed with a phospholipid-binding protein. Protein kinase A-mediated phosphorylation enhances PtdCho synthesis and may allow PtdCho accumulation by coordinate inhibition of NTE activity. NTE operates primarily at the endoplasmic reticulum in neuronal soma but is also present in axons. NTE-mediated PtdCho homeostasis facilitates membrane trafficking and this appears most critical for the integrity of axon terminals in the spinal cord and hippocampus. For maintenance of peripheral nerve axons, iPLA2β activity may be able to compensate for NTE-deficiency but not vice-versa. Whether agonists acting at neuronal receptors modulate the activity of either enzyme remains to be determined. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Affiliation(s)
- Paul Glynn
- Department of Cell Physiology & Pharmacology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK.
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18
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Emerick GL, DeOliveira GH, dos Santos AC, Ehrich M. Mechanisms for consideration for intervention in the development of organophosphorus-induced delayed neuropathy. Chem Biol Interact 2012; 199:177-84. [PMID: 22819951 DOI: 10.1016/j.cbi.2012.07.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 07/05/2012] [Accepted: 07/11/2012] [Indexed: 11/15/2022]
Abstract
Organophosphorus-induced delayed neuropathy (OPIDN) is a neurodegenerative disorder characterised by ataxia progressing to paralysis with concomitant central and peripheral distal axonopathy. Symptoms of OPIDN in people include tingling of the hands and feet. This tingling is followed by sensory loss, progressive muscle weakness and flaccidity of the distal skeletal muscles of the lower and upper extremities and ataxia, which appear about 8-14 days after exposure. Some organophosphorus compounds (OPs) that are still used in worldwide agriculture have potential to induce OPIDN, including methamidophos, trichlorfon, dichlorvos and chorpyrifos. This review summarizes experimental attempts to prevent and/or treat OPIDN and the different mechanisms involved in each approach. The initial mechanism associated with development of OPIDN is phosphorylation and inhibition of neuropathy target esterase (NTE). The phosphorylated enzyme undergoes a second reaction known as "aging" that results in the loss of one of the "R" groups bound to the phosphorus of the OP. A second mechanism involved in OPIDN is an imbalance in calcium homeostasis. This can lead to the activation of calcium-activated neutral protease and increases in calcium/calmodulin-dependent protein kinases. These events contribute to aberrant phosphorylation of cytoskeletal proteins and protein digestion in the terminal axon that can proceed similarly to Wallerian-type degeneration. Several experimental studies demonstrated alleviation of the signs and symptoms of OPIDN by restoring calcium balance. Other studies have used preadministration of NTE inhibitors, such as carbamates, thiocarbamates, sulfonyl fluorides and phosphinate to prevent OPIDN. Progress is being made, but there is yet no single specific treatment available for use in clinical practice to prevent or alleviate the severe effects of OPIDN.
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Affiliation(s)
- Guilherme L Emerick
- Department of Natural Active Principles and Toxicology, School of Pharmaceutical Sciences, Univ Estadual Paulista - UNESP, Araraquara, SP, Brazil.
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19
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Radchenko EV, Mel’nikov AA, Makhaeva GF, Palyulin VA, Zefirov NS. Molecular design of O-phosphorylated oximes—Selective inhibitors of butyrylcholinesterase. DOKL BIOCHEM BIOPHYS 2012; 443:91-5. [DOI: 10.1134/s1607672912020093] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Indexed: 11/23/2022]
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20
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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]
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