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Encarnação M, Ribeiro I, David H, Coutinho MF, Quelhas D, Alves S. Challenges in the Definitive Diagnosis of Niemann-Pick Type C-Leaky Variants and Alternative Transcripts. Genes (Basel) 2023; 14:1990. [PMID: 38002933 PMCID: PMC10671040 DOI: 10.3390/genes14111990] [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: 09/29/2023] [Revised: 10/17/2023] [Accepted: 10/23/2023] [Indexed: 11/26/2023] Open
Abstract
Niemann-Pick type C (NPC, ORPHA: 646) is a neuro-visceral, psychiatric disease caused predominantly by pathogenic variants in the NPC1 gene or seldom in NPC2. The rarity of the disease, and its wide range of clinical phenotypes and ages of onset, turn the diagnosis into a significant challenge. Other than the detailed clinical history, the typical diagnostic work-up for NPC includes the quantification of pathognomonic metabolites. However, the molecular basis diagnosis is still of utmost importance to fully characterize the disorder. Here, the authors provide an overview of splicing variants in the NPC1 and NPC2 genes and propose a new workflow for NPC diagnosis. Splicing variants cover a significant part of the disease-causing variants in NPC. The authors used cDNA analysis to study the impact of such variants, including the collection of data to classify them as leaky or non-leaky pathogenic variants. However, the presence of naturally occurring spliced transcripts can misdiagnose or mask a pathogenic variant and make the analysis even more difficult. Analysis of the NPC1 cDNA in NPC patients in parallel with controls is vital to assess and detect alternatively spliced forms. Moreover, nonsense-mediated mRNA decay (NMD) analysis plays an essential role in evaluating the naturally occurring transcripts during cDNA analysis and distinguishing them from other pathogenic variants' associated transcripts.
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Affiliation(s)
- Marisa Encarnação
- Research and Development Unit, Department of Human Genetics, National Institute of Health Doutor Ricardo Jorge, INSA I.P., Rua Alexandre Herculano, 321, 4000-055 Porto, Portugal; (M.E.); (H.D.); (M.F.C.)
- Center for the Study of Animal Science-Instituto de Ciências, Tecnologias e Agroambiente da Universidade do Porto, CECA-ICETA, University of Porto, Praça Gomes Teixeira, Apartado 55142, 4051-401 Porto, Portugal
- Associate Laboratory for Animal and Veterinary Sciences, AL4AnimalS, Faculdade de Medicina Veterinária Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Isaura Ribeiro
- Laboratório de Bioquímica Genética, Serviço de Genética Laboratorial, Centro de Genética Médica Jacinto Magalhães, Centro Hospitalar e Universitário de Santo António (CHUdSA), 4099-001 Porto, Portugal; (I.R.); (D.Q.)
- UMIB-Unit for Multidisciplinary Research in Biomedicine, ICBAS, University of Porto, 4099-002 Porto, Portugal
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-600 Porto, Portugal
| | - Hugo David
- Research and Development Unit, Department of Human Genetics, National Institute of Health Doutor Ricardo Jorge, INSA I.P., Rua Alexandre Herculano, 321, 4000-055 Porto, Portugal; (M.E.); (H.D.); (M.F.C.)
- Center for the Study of Animal Science-Instituto de Ciências, Tecnologias e Agroambiente da Universidade do Porto, CECA-ICETA, University of Porto, Praça Gomes Teixeira, Apartado 55142, 4051-401 Porto, Portugal
- Associate Laboratory for Animal and Veterinary Sciences, AL4AnimalS, Faculdade de Medicina Veterinária Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
- Biology Department, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
| | - Maria Francisca Coutinho
- Research and Development Unit, Department of Human Genetics, National Institute of Health Doutor Ricardo Jorge, INSA I.P., Rua Alexandre Herculano, 321, 4000-055 Porto, Portugal; (M.E.); (H.D.); (M.F.C.)
- Center for the Study of Animal Science-Instituto de Ciências, Tecnologias e Agroambiente da Universidade do Porto, CECA-ICETA, University of Porto, Praça Gomes Teixeira, Apartado 55142, 4051-401 Porto, Portugal
- Associate Laboratory for Animal and Veterinary Sciences, AL4AnimalS, Faculdade de Medicina Veterinária Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Dulce Quelhas
- Laboratório de Bioquímica Genética, Serviço de Genética Laboratorial, Centro de Genética Médica Jacinto Magalhães, Centro Hospitalar e Universitário de Santo António (CHUdSA), 4099-001 Porto, Portugal; (I.R.); (D.Q.)
- UMIB-Unit for Multidisciplinary Research in Biomedicine, ICBAS, University of Porto, 4099-002 Porto, Portugal
- ITR—Laboratory for Integrative and Translational Research in Population Health, 4050-600 Porto, Portugal
| | - Sandra Alves
- Research and Development Unit, Department of Human Genetics, National Institute of Health Doutor Ricardo Jorge, INSA I.P., Rua Alexandre Herculano, 321, 4000-055 Porto, Portugal; (M.E.); (H.D.); (M.F.C.)
- Center for the Study of Animal Science-Instituto de Ciências, Tecnologias e Agroambiente da Universidade do Porto, CECA-ICETA, University of Porto, Praça Gomes Teixeira, Apartado 55142, 4051-401 Porto, Portugal
- Associate Laboratory for Animal and Veterinary Sciences, AL4AnimalS, Faculdade de Medicina Veterinária Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
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Majer F, Asfaw B, Kuchař L, Mušálková D, Steiner-Mrázová L, Dobrovolný R, Ledvinová J, Hřebíček M. Loading of cell cultures with cholesterol-dextran particles as a new functional test for Niemann-Pick type C disease. J Inherit Metab Dis 2022; 45:584-592. [PMID: 35088900 DOI: 10.1002/jimd.12481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/07/2022] [Accepted: 01/25/2022] [Indexed: 11/09/2022]
Abstract
Deuterium-labeled cholesterol-dextran particles (d4-CholDex), prepared by co-precipitation, were internalized by cultured human skin fibroblasts and HEK293 cells. Subcellular particles from d4-CholDex-treated HEK293 cells were fractionated on iodixanol gradients. More than 60% of d4-cholesterol (d4-UC) in the gradient co-fractionated with lysosomal markers and NPC1. This and formation of d4-cholesteryl esters (d4-CE) in the cells suggests that d4-CholDex is lysosomally processed. In accordance with these findings, we observed an increase in lysosomal cholesterol content by fluorescence microscopy in CholDex-loaded cells. Fibroblast cultures including 13 NPC1-deficient, four heterozygous and six control lines were treated with d4-CholDex at final d4-UC concentration of 0.05 mg/ml (127.98 μmol/L) for 3 h and chased for 48 h in medium without d4-CholDex. Concentrations of d4-UC and d4-CE in harvested cells were measured by tandem mass spectrometry (MS/MS). d4-UC/d4-CE ratios were elevated in NP-C lines compared to controls (n = 6, mean = 4.36, range = 1.89-8.91), with the highest ratios in severe NP-C1 phenotypes and the lowest in adolescent/adult type patients. There were overlaps between NP-C1 forms: early infantile (n = 1, mean = 48.6), late infantile (n = 4, mean = 36.3, range = 20.6-54.0), juvenile (n = 5, mean = 24.7, range = 13.4-38.3), adolescent/adult (n = 3, mean = 14.5, range = 11.7-19.8). The ratios in NP-C1 heterozygotes were mildly elevated (n = 4, mean = 16.4, range = 14.9-17.4) and comparable to patients with adolescent/adult NP-C1. The test can be useful in evaluation of suspected NP-C patients with inconclusive results of biomarker or molecular tests. Its advantages include standardized preparation of particles with longer shelf life at 4 °C, quantitative results, and no requirement for radioactive chemicals.
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Affiliation(s)
- Filip Majer
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Befekadu Asfaw
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Ladislav Kuchař
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Dita Mušálková
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Lenka Steiner-Mrázová
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Robert Dobrovolný
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Jana Ledvinová
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Martin Hřebíček
- Research Unit for Rare Diseases, Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
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Evelina M, Roberto F, Caterina R, Federica D, Giovanni P, Vincenza G, Alberto B, Massimo S. ATHEROGENIC LIPID PROFILE IN PATIENTS WITH NIEMANN-PICK DISEASE TYPE B: WHAT TREATMENT STRATEGIES? J Clin Lipidol 2022; 16:143-154. [DOI: 10.1016/j.jacl.2022.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 11/05/2021] [Accepted: 01/24/2022] [Indexed: 11/26/2022]
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Völkner C, Liedtke M, Untucht R, Hermann A, Frech MJ. Patient-Specific iPSC-Derived Neural Differentiated and Hepatocyte-like Cells, Carrying the Compound Heterozygous Mutation p.V1023Sfs*15/p.G992R, Present the "Variant" Biochemical Phenotype of Niemann-Pick Type C1 Disease. Int J Mol Sci 2021; 22:ijms222212184. [PMID: 34830064 PMCID: PMC8624182 DOI: 10.3390/ijms222212184] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/03/2021] [Accepted: 11/08/2021] [Indexed: 02/07/2023] Open
Abstract
Niemann–Pick disease type C1 (NP-C1) is a rare lysosomal storage disorder caused by autosomal recessive mutations in the NPC1 gene. Patients display a wide spectrum on the clinical as well as on the molecular level, wherein a so-called “variant” biochemical phenotype can be observed. Here, we report an in vitro analysis of fibroblasts obtained from an NP-C1 patient carrying the undescribed compound heterozygous mutation p.V1023Sfs*15/p.G992R. Since NP-C1 is a neurovisceral disease and the patient suffers from severe neurological as well as hepatic symptoms, we extended our study to neural differentiated and hepatocyte-like cells derived from patient-specific induced pluripotent stem cells. We detected slightly increased intracellular cholesterol levels compared to the control cell line in fibroblasts, neural differentiated and hepatocyte-like cells, suggesting a “variant” biochemical phenotype. Furthermore, the total NPC1 protein, as well as post-ER glycoforms of the NPC1 protein, tended to be reduced. In addition, colocalization analysis revealed a mild reduction of the NPC1 protein in the lysosomes. The patient was diagnosed with NP-C1 at the age of 34 years, after an initial misdiagnosis of schizophrenia. After years of mild and unspecific symptoms, such as difficulties in coordination and concentration, symptoms progressed and the patient finally presented with ataxia, dysarthria, dysphagia, vertical supranuclear gaze palsy, and hepatosplenomegaly. Genetic testing finally pointed towards an NP-C1 diagnosis, revealing the so-far undescribed compound heterozygous mutation p.V1023Sfs*15/p.G992R in the NPC1 gene. In light of these findings, this case provides support for the p.G992R mutation being causative for a “variant” biochemical phenotype leading to an adult-onset type of NP-C1 disease.
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Affiliation(s)
- Christin Völkner
- Translational Neurodegeneration Section “Albrecht Kossel”, Department of Neurology, University Medical Center Rostock, 18147 Rostock, Germany; (C.V.); (M.L.); (A.H.)
| | - Maik Liedtke
- Translational Neurodegeneration Section “Albrecht Kossel”, Department of Neurology, University Medical Center Rostock, 18147 Rostock, Germany; (C.V.); (M.L.); (A.H.)
| | - Robert Untucht
- Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany;
| | - Andreas Hermann
- Translational Neurodegeneration Section “Albrecht Kossel”, Department of Neurology, University Medical Center Rostock, 18147 Rostock, Germany; (C.V.); (M.L.); (A.H.)
- Center for Transdisciplinary Neurosciences Rostock (CTNR), University Medical Center Rostock, 18147 Rostock, Germany
- German Center for Neurodegenerative Diseases (DZNE) Rostock/Greifswald, 18147 Rostock, Germany
| | - Moritz J. Frech
- Translational Neurodegeneration Section “Albrecht Kossel”, Department of Neurology, University Medical Center Rostock, 18147 Rostock, Germany; (C.V.); (M.L.); (A.H.)
- Center for Transdisciplinary Neurosciences Rostock (CTNR), University Medical Center Rostock, 18147 Rostock, Germany
- Correspondence:
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5
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Ebrahimi-Fakhari D, Alecu JE, Brechmann B, Ziegler M, Eberhardt K, Jumo H, D’Amore A, Habibzadeh P, Faghihi MA, De Bleecker JL, Vuillaumier-Barrot S, Auvin S, Santorelli FM, Neuser S, Popp B, Yang E, Barrett L, Davies AK, Saffari A, Hirst J, Sahin M. High-throughput imaging of ATG9A distribution as a diagnostic functional assay for adaptor protein complex 4-associated hereditary spastic paraplegia. Brain Commun 2021; 3:fcab221. [PMID: 34729478 PMCID: PMC8557665 DOI: 10.1093/braincomms/fcab221] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/05/2021] [Accepted: 08/19/2021] [Indexed: 01/09/2023] Open
Abstract
Adaptor protein complex 4-associated hereditary spastic paraplegia is caused by biallelic loss-of-function variants in AP4B1, AP4M1, AP4E1 or AP4S1, which constitute the four subunits of this obligate complex. While the diagnosis of adaptor protein complex 4-associated hereditary spastic paraplegia relies on molecular testing, the interpretation of novel missense variants remains challenging. Here, we address this diagnostic gap by using patient-derived fibroblasts to establish a functional assay that measures the subcellular localization of ATG9A, a transmembrane protein that is sorted by adaptor protein complex 4. Using automated high-throughput microscopy, we determine the ratio of the ATG9A fluorescence in the trans-Golgi-network versus cytoplasm and ascertain that this metric meets standards for screening assays (Z'-factor robust >0.3, strictly standardized mean difference >3). The 'ATG9A ratio' is increased in fibroblasts of 18 well-characterized adaptor protein complex 4-associated hereditary spastic paraplegia patients [mean: 1.54 ± 0.13 versus 1.21 ± 0.05 (standard deviation) in controls] and receiver-operating characteristic analysis demonstrates robust diagnostic power (area under the curve: 0.85, 95% confidence interval: 0.849-0.852). Using fibroblasts from two individuals with atypical clinical features and novel biallelic missense variants of unknown significance in AP4B1, we show that our assay can reliably detect adaptor protein complex 4 function. Our findings establish the 'ATG9A ratio' as a diagnostic marker of adaptor protein complex 4-associated hereditary spastic paraplegia.
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Affiliation(s)
- Darius Ebrahimi-Fakhari
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
- The Manton Center for Orphan Disease Research, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Julian E Alecu
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Barbara Brechmann
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
- Division of Neuropediatrics and Inherited Metabolic Diseases, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Marvin Ziegler
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
- Ruprecht-Karls University Heidelberg, Medical School, 69120 Heidelberg, Germany
| | - Kathrin Eberhardt
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Hellen Jumo
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Angelica D’Amore
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Parham Habibzadeh
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, 71347 Shiraz, Iran
| | - Mohammad Ali Faghihi
- Department of Psychiatry and Behavioral Sciences, University of Miami, Miami, FL 33136, USA
| | - Jan L De Bleecker
- Department of Neurology, Ghent University Hospital, 9000 Ghent, Belgium
| | | | - Stéphane Auvin
- Pediatric Neurology Department, AP-HP, Robert Debré Hospital, 75019 Paris, France
| | - Filippo M Santorelli
- Department of Molecular Medicine, IRCCS Fondazione Stella Maris, 56128 Pisa, Italy
| | - Sonja Neuser
- Institute of Human Genetics, University of Leipzig Medical Center, 04103 Leipzig, Germany
| | - Bernt Popp
- Institute of Human Genetics, University of Leipzig Medical Center, 04103 Leipzig, Germany
| | - Edward Yang
- Division of Neuroradiology, Department of Radiology, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Lee Barrett
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children’s Hospital, Boston, MA 02115, USA
| | - Alexandra K Davies
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Afshin Saffari
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
- Division of Neuropediatrics and Inherited Metabolic Diseases, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Jennifer Hirst
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Mustafa Sahin
- Department of Neurology, The F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children’s Hospital, Boston, MA 02115, USA
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Encarnação M, Coutinho MF, Cho SM, Cardoso MT, Ribeiro I, Chaves P, Santos JI, Quelhas D, Lacerda L, Leão Teles E, Futerman AH, Vilarinho L, Alves S. NPC1 silent variant induces skipping of exon 11 (p.V562V) and unfolded protein response was found in a specific Niemann-Pick type C patient. Mol Genet Genomic Med 2020; 8:e1451. [PMID: 32931663 PMCID: PMC7667330 DOI: 10.1002/mgg3.1451] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 06/27/2020] [Accepted: 07/22/2020] [Indexed: 01/31/2023] Open
Abstract
Background Niemann‐Pick type C (NPC, MIM #257220) is a neuro‐visceral disease, caused predominantly by pathogenic variants in the NPC1 gene. Here we studied patients with clinical diagnosis of NPC but inconclusive results regarding the molecular analysis. Methods We used a Next‐Generation Sequencing (NGS)‐panel followed by cDNA analysis. Latter, we used massively parallel single‐cell RNA‐seq (MARS‐Seq) to address gene profiling changes and finally the effect of different variants on the protein and cellular levels. Results We identified novel variants and cDNA analysis allowed us to establish the functional effect of a silent variant, previously reported as a polymorphism. We demonstrated that this variant induces the skipping of exon 11 leading to a premature stop codon and identified it in NPC patients from two unrelated families. MARS‐Seq analysis showed that a number of upregulated genes were related to the unfolded protein response (UPR) and endoplasmic reticulum (ER) stress in one specific patient. Also, for all analyzed variants, the NPC1 protein was partially retained in the ER. Conclusion We showed that the NPC1 silent polymorphism (p.V562V) is a disease‐causing variant in NPC and that the UPR is upregulated in an NPC patient.
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Affiliation(s)
- Marisa Encarnação
- Research & Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, Porto, Portugal.,Newborn Screening, Metabolism & Genetics Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, Porto, Portugal.,Center for the Study of Animal Science, CECA-ICETA, University of Porto, Porto, Portugal
| | - Maria Francisca Coutinho
- Research & Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, Porto, Portugal.,Center for the Study of Animal Science, CECA-ICETA, University of Porto, Porto, Portugal
| | - Soo Min Cho
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Maria Teresa Cardoso
- Centro de Referência de Doenças Metabólicas do Centro Hospitalar, Universitário São João, Porto, Portugal
| | - Isaura Ribeiro
- Unidade de Bioquímica Genética, Centro de Genética Médica Jacinto Magalhães - Centro Hospitalar e Universitário do Porto (CHP), Porto, Portugal.,Clinical and Experimental Human Genomics group (CEHG), UMIB-Unit for Multidisciplinary Research in Biomedicine, ICBAS, University of Porto, Porto, Portugal.,MetabERN-European Reference Network for Rare Hereditary Metabolic Disorder, Reference Centre for Diagnosis and Treatment - CHP, Porto, Portugal
| | - Paulo Chaves
- Centro de Referência de Doenças Metabólicas do Centro Hospitalar, Universitário São João, Porto, Portugal
| | - Juliana Inês Santos
- Research & Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, Porto, Portugal
| | - Dulce Quelhas
- Unidade de Bioquímica Genética, Centro de Genética Médica Jacinto Magalhães - Centro Hospitalar e Universitário do Porto (CHP), Porto, Portugal.,Clinical and Experimental Human Genomics group (CEHG), UMIB-Unit for Multidisciplinary Research in Biomedicine, ICBAS, University of Porto, Porto, Portugal.,MetabERN-European Reference Network for Rare Hereditary Metabolic Disorder, Reference Centre for Diagnosis and Treatment - CHP, Porto, Portugal
| | - Lúcia Lacerda
- Unidade de Bioquímica Genética, Centro de Genética Médica Jacinto Magalhães - Centro Hospitalar e Universitário do Porto (CHP), Porto, Portugal.,Clinical and Experimental Human Genomics group (CEHG), UMIB-Unit for Multidisciplinary Research in Biomedicine, ICBAS, University of Porto, Porto, Portugal.,MetabERN-European Reference Network for Rare Hereditary Metabolic Disorder, Reference Centre for Diagnosis and Treatment - CHP, Porto, Portugal
| | - Elisa Leão Teles
- Centro de Referência de Doenças Metabólicas do Centro Hospitalar, Universitário São João, Porto, Portugal
| | - Anthony H Futerman
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Laura Vilarinho
- Research & Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, Porto, Portugal.,Newborn Screening, Metabolism & Genetics Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, Porto, Portugal.,Center for the Study of Animal Science, CECA-ICETA, University of Porto, Porto, Portugal
| | - Sandra Alves
- Research & Development Unit, Human Genetics Department, National Institute of Health Doutor Ricardo Jorge, Porto, Portugal.,Center for the Study of Animal Science, CECA-ICETA, University of Porto, Porto, Portugal
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Paron F, Dardis A, Buratti E. Pre-mRNA splicing defects and RNA binding protein involvement in Niemann Pick type C disease. J Biotechnol 2020; 318:20-30. [PMID: 32387451 DOI: 10.1016/j.jbiotec.2020.03.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 03/25/2020] [Accepted: 03/26/2020] [Indexed: 12/22/2022]
Abstract
Niemann-Pick type C (NPC) is an autosomal recessive lysosomal storage disorder due to mutations in NPC1 (95 % cases) or NPC2 genes, encoding NPC1 and NPC2 proteins, respectively. Both NPC1 and NPC2 proteins are involved in transport of intracellular cholesterol and their alteration leads to the accumulation of unesterified cholesterol and other lipids within the lysosomes. The disease is characterized by visceral, neurological and psychiatric symptoms. However, the pathogenic mechanisms that lead to the fatal neurodegeneration are still unclear. To date, several mutations leading to the generation of aberrant splicing variants or mRNA degradation in NPC1 and NPC2 genes have been reported. In addition, different lines of experimental evidence have highlighted the possible role of RNA-binding proteins and RNA-metabolism, in the onset and progression of many neurodegenerative disorders, that could explain NPC neurological features and in general, the disease pathogenesis. In this review, we will provide an overview of the impact of mRNA processing and metabolism on NPC disease pathology.
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Affiliation(s)
- Francesca Paron
- Molecular Pathology, International Institute for Genetic Engineering and Biotechnology, Trieste, Italy.
| | - Andrea Dardis
- Regional Coordinator Centre for Rare Diseases, Academic Hospital Santa Maria della Misericordia, Udine, Italy.
| | - Emanuele Buratti
- Molecular Pathology, International Institute for Genetic Engineering and Biotechnology, Trieste, Italy.
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8
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Subramanian K, Hutt DM, Scott SM, Gupta V, Mao S, Balch WE. Correction of Niemann-Pick type C1 trafficking and activity with the histone deacetylase inhibitor valproic acid. J Biol Chem 2020; 295:8017-8035. [PMID: 32354745 DOI: 10.1074/jbc.ra119.010524] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 04/13/2020] [Indexed: 12/12/2022] Open
Abstract
Niemann-Pick type C (NPC) disease is primarily caused by mutations in the NPC1 gene and is characterized by the accumulation of unesterified cholesterol and lipids in the late endosomal (LE) and lysosomal (Ly) compartments. The most prevalent disease-linked mutation is the I1061T variant of NPC1, which exhibits defective folding and trafficking from the endoplasmic reticulum to the LE/Ly compartments. We now show that the FDA-approved histone deacetylase inhibitor (HDACi) valproic acid (VPA) corrects the folding and trafficking defect associated with I1061T-NPC1 leading to restoration of cholesterol homeostasis, an effect that is largely driven by a reduction in HDAC7 expression. The VPA-mediated trafficking correction is in part associated with an increase in the acetylation of lysine residues in the cysteine-rich domain of NPC1. The HDACi-mediated correction is synergistically improved by combining it with the FDA-approved anti-malarial, chloroquine, a known lysosomotropic compound, which improved the stability of the LE/Ly-localized fraction of the I1061T variant. We posit that combining the activity of VPA, to modulate epigenetically the cellular acetylome, with chloroquine, to alter the lysosomal environment to favor stability of the trafficked I1061T variant protein can have a significant therapeutic benefit in patients carrying at least one copy of the I1061T variant of NPC1, the most common disease-associated mutation leading to NPC disease. Given its ability to cross the blood-brain barrier, we posit VPA provides a potential mechanism to improve the response to 2-hydroxypropyl-β-cyclodextrin, by restoring a functional NPC1 to the cholesterol managing compartment as an adjunct therapy.
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Affiliation(s)
| | - Darren M Hutt
- Department of Molecular Medicine, Scripps Research, La Jolla, California, USA
| | - Samantha M Scott
- Department of Molecular Medicine, Scripps Research, La Jolla, California, USA
| | - Vijay Gupta
- Department of Molecular Medicine, Scripps Research, La Jolla, California, USA
| | - Shu Mao
- Department of Biochemistry, Weill Cornell Medical College, New York, New York, USA
| | - William E Balch
- Department of Molecular Medicine, Scripps Research, La Jolla, California, USA
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9
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Musalkova D, Majer F, Kuchar L, Luksan O, Asfaw B, Vlaskova H, Storkanova G, Reboun M, Poupetova H, Jahnova H, Hulkova H, Ledvinova J, Dvorakova L, Sikora J, Jirsa M, Vanier MT, Hrebicek M. Transcript, protein, metabolite and cellular studies in skin fibroblasts demonstrate variable pathogenic impacts of NPC1 mutations. Orphanet J Rare Dis 2020; 15:85. [PMID: 32248828 PMCID: PMC7132889 DOI: 10.1186/s13023-020-01360-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/17/2020] [Indexed: 12/18/2022] Open
Abstract
Background Niemann-Pick type C (NP-C) is a rare neurovisceral genetic disorder caused by mutations in the NPC1 or the NPC2 gene. NPC1 is a multipass-transmembrane protein essential for egress of cholesterol from late endosomes/lysosomes. To evaluate impacts of NPC1 mutations, we examined fibroblast cultures from 26 NP-C1 patients with clinical phenotypes ranging from infantile to adult neurologic onset forms. The cells were tested with multiple assays including NPC1 mRNA expression levels and allele expression ratios, assessment of NPC1 promoter haplotypes, NPC1 protein levels, cellular cholesterol staining, localization of the mutant NPC1 proteins to lysosomes, and cholesterol/cholesteryl ester ratios. These results were correlated with phenotypes of the individual patients. Results Overall we identified 5 variant promoter haplotypes. Three of them showed reporter activity decreased down to 70% of the control sequence. None of the haplotypes were consistently associated with more severe clinical presentation of NP-C. Levels of transcripts carrying null NPC1 alleles were profoundly lower than levels of the missense variants. Low levels of the mutant NPC1 protein were identified in most samples. The protein localised to lysosomes in cultures expressing medium to normal NPC1 levels. Fibroblasts from patients with severe infantile phenotypes had higher cholesterol levels and higher cholesterol/cholesteryl ester ratios. On the contrary, cell lines from patients with juvenile and adolescent/adult phenotypes showed values comparable to controls. Conclusion No single assay fully correlated with the disease severity. However, low residual levels of NPC1 protein and high cholesterol/cholesteryl ester ratios associated with severe disease. The results suggest not only low NPC1 expression due to non-sense mediated decay or low mutant protein stability, but also dysfunction of the stable mutant NPC1 as contributors to the intracellular lipid transport defect.
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Affiliation(s)
- Dita Musalkova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Filip Majer
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic.
| | - Ladislav Kuchar
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Ondrej Luksan
- Laboratory of Experimental Hepatology, Institute of Clinical and Experimental Medicine, Prague, Czech Republic
| | - Befekadu Asfaw
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Hana Vlaskova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Gabriela Storkanova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Martin Reboun
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Helena Poupetova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Helena Jahnova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Helena Hulkova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Jana Ledvinova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Lenka Dvorakova
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Jakub Sikora
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic
| | - Milan Jirsa
- Laboratory of Experimental Hepatology, Institute of Clinical and Experimental Medicine, Prague, Czech Republic
| | - Marie T Vanier
- INSERM U820, Lyon, France.,Laboratoire Gillet-Mérieux, Lyon University Hospitals (HCL), Lyon, France
| | - Martin Hrebicek
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, Ke Karlovu 2, 120 00, Prague 2, Czech Republic.
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10
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Different Trafficking Phenotypes of Niemann-Pick C1 Gene Mutations Correlate with Various Alterations in Lipid Storage, Membrane Composition and Miglustat Amenability. Int J Mol Sci 2020; 21:ijms21062101. [PMID: 32204338 PMCID: PMC7139583 DOI: 10.3390/ijms21062101] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 03/15/2020] [Accepted: 03/16/2020] [Indexed: 12/24/2022] Open
Abstract
Niemann-Pick Type C (NPC) is an autosomal recessive lysosomal storage disease leading to progressive neurodegeneration. Mutations in the NPC1 gene, which accounts for 95% of the cases, lead to a defect in intra-lysosomal trafficking of cholesterol and an accumulation of storage material including cholesterol and sphingolipids in the endo-lysosomal system. Symptoms are progressive neurological and visceral deterioration, with variable onset and severity of the disease. This study investigates the influence of two different NPC1 mutations on the biochemical phenotype in fibroblasts isolated from NPC patients in comparison to healthy, wild type (WT) cells. Skin derived fibroblasts were cultured from one patient compound-heterozygous for D874V/D948Y mutations, which presented wild-type like intracellular trafficking of NPC1, and a second patient compound- heterozygous for I1061T/P887L mutations, which exhibited a more severe biochemical phenotype as revealed in the delayed trafficking of NPC1. Biochemical analysis using HPLC and TLC indicated that lipid accumulations were mutation-dependent and correlated with the trafficking pattern of NPC1: higher levels of cholesterol and glycolipids were associated with the mutations that exhibited delayed intracellular trafficking, as compared to their WT-like trafficked or wild type (WT) counterparts. Furthermore, variations in membrane structure was confirmed in these cell lines based on alteration in lipid rafts composition as revealed by the shift in flotillin-2 (FLOT2) distribution, a typical lipid rafts marker, which again showed marked alterations only in the NPC1 mutant showing major trafficking delay. Finally, treatment with N-butyldeoxynojirimycin (NB-DNJ, Miglustat) led to a reduction of stored lipids in cells from both patients to various extents, however, no normalisation in lipid raft structure was achieved. The data presented in this study help in understanding the varying biochemical phenotypes observed in patients harbouring different mutations, which explain why the effectiveness of NB-DNJ treatment is patient specific.
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11
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Molecular Genetics of Niemann-Pick Type C Disease in Italy: An Update on 105 Patients and Description of 18 NPC1 Novel Variants. J Clin Med 2020; 9:jcm9030679. [PMID: 32138288 PMCID: PMC7141276 DOI: 10.3390/jcm9030679] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/19/2020] [Accepted: 02/25/2020] [Indexed: 02/07/2023] Open
Abstract
Niemann-Pick type C (NPC) disease is an autosomal recessive lysosomal storage disorder caused by mutations in NPC1 or NPC2 genes. In 2009, the molecular characterization of 44 NPC Italian patients has been published. Here, we present an update of the genetic findings in 105 Italian NPC patients belonging to 83 unrelated families (77 NPC1 and 6 NPC2). NPC1 and NPC2 genes were studied following an algorithm recently published. Eighty-four different NPC1 and five NPC2 alleles were identified. Only two NPC1 alleles remained non detected. Sixty-two percent of NPC1 alleles were due to missense variants. The most frequent NPC1 mutation was the p.F284Lfs*26 (5.8% of the alleles). All NPC2 mutations were found in the homozygous state, and all but one was severe. Among newly diagnosed patients, 18 novel NPC1 mutations were identified. The pathogenic nature of 7/9 missense alleles and 3/4 intronic variants was confirmed by filipin staining and NPC1 protein analysis or mRNA expression in patient’s fibroblasts. Taken together, our previous published data and new results provide an overall picture of the molecular characteristics of NPC patients diagnosed so far in Italy.
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12
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Wang C, Scott SM, Subramanian K, Loguercio S, Zhao P, Hutt DM, Farhat NY, Porter FD, Balch WE. Quantitating the epigenetic transformation contributing to cholesterol homeostasis using Gaussian process. Nat Commun 2019; 10:5052. [PMID: 31699992 PMCID: PMC6838179 DOI: 10.1038/s41467-019-12969-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 10/10/2019] [Indexed: 12/11/2022] Open
Abstract
To understand the impact of epigenetics on human misfolding disease, we apply Gaussian-process regression (GPR) based machine learning (ML) (GPR-ML) through variation spatial profiling (VSP). VSP generates population-based matrices describing the spatial covariance (SCV) relationships that link genetic diversity to fitness of the individual in response to histone deacetylases inhibitors (HDACi). Niemann-Pick C1 (NPC1) is a Mendelian disorder caused by >300 variants in the NPC1 gene that disrupt cholesterol homeostasis leading to the rapid onset and progression of neurodegenerative disease. We determine the sequence-to-function-to-structure relationships of the NPC1 polypeptide fold required for membrane trafficking and generation of a tunnel that mediates cholesterol flux in late endosomal/lysosomal (LE/Ly) compartments. HDACi treatment reveals unanticipated epigenomic plasticity in SCV relationships that restore NPC1 functionality. GPR-ML based matrices capture the epigenetic processes impacting information flow through central dogma, providing a framework for quantifying the effect of the environment on the healthspan of the individual.
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Affiliation(s)
- Chao Wang
- Department of Molecular Medicine, Scripps Research, La Jolla, CA, 92037, USA
| | - Samantha M Scott
- Department of Molecular Medicine, Scripps Research, La Jolla, CA, 92037, USA
| | | | - Salvatore Loguercio
- Department of Molecular Medicine, Scripps Research, La Jolla, CA, 92037, USA
| | - Pei Zhao
- Department of Molecular Medicine, Scripps Research, La Jolla, CA, 92037, USA
| | - Darren M Hutt
- Department of Molecular Medicine, Scripps Research, La Jolla, CA, 92037, USA
| | - Nicole Y Farhat
- Section on Molecular Dysmorphology, Division of Translational Medicine, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20814, USA
| | - Forbes D Porter
- Section on Molecular Dysmorphology, Division of Translational Medicine, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20814, USA
| | - William E Balch
- Department of Molecular Medicine, Scripps Research, La Jolla, CA, 92037, USA.
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13
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Determination of the Pathological Features of NPC1 Variants in a Cellular Complementation Test. Int J Mol Sci 2019; 20:ijms20205185. [PMID: 31635081 PMCID: PMC6834306 DOI: 10.3390/ijms20205185] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 10/09/2019] [Accepted: 10/15/2019] [Indexed: 12/20/2022] Open
Abstract
Niemann-Pick Type C (NP-C) is a rare disorder of lipid metabolism caused by mutations within the NPC1 and NPC2 genes. NP-C is a neurovisceral disease leading to a heterogeneous, multisystemic spectrum of symptoms in those affected. Until now, there is no investigative tool to demonstrate the significance of single variants within the NPC genes. Hence, the aim of the study was to establish a test that allows for an objective assessment of the pathological potential of NPC1 gene variants. Chinese hamster ovary cells defective in the NPC1 gene accumulate cholesterol in lysosomal storage organelles. The cells were transfected with NPC1-GFP plasmid vectors carrying distinct sequence variants. Filipin staining was used to test for complementation of the phenotype. The known variant p.Ile1061Thr showed a significantly impaired cholesterol clearance after 12 and 24 h compared to the wild type. Among the investigated variants, p.Ser954Leu and p.Glu1273Lys showed decelerated cholesterol clearance as well. The remaining variants p.Gln60His, p.Val494Met, and p.Ile787Val showed a cholesterol clearance indistinguishable from wild type. Further, p.Ile1061Thr acquired an enhanced clearance ability upon 25-hydroxycholesterol treatment. We conclude that the variants that caused an abnormal clearance phenotype are highly likely to be of clinical relevance. Moreover, we present a system that can be utilized to screen for new drugs.
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14
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LaLone V, Fawaz MV, Morales-Mercado J, Mourão MA, Snyder CS, Kim SY, Lieberman AP, Tuteja A, Mehta G, Standiford TJ, Raghavendran K, Shedden K, Schwendeman A, Stringer KA, Rosania GR. Inkjet-printed micro-calibration standards for ultraquantitative Raman spectral cytometry. Analyst 2019; 144:3790-3799. [PMID: 31116195 PMCID: PMC6711383 DOI: 10.1039/c9an00500e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein we report the development of a cytometric analysis platform for measuring the contents of individual cells in absolute (picogram) scales; this study represents the first report of Raman-based quantitation of the absolute mass - or the total amount - of multiple endogenous biomolecules within single-cells. To enable ultraquantitative calibration, we engineered single-cell-sized micro-calibration standards of known composition by inkjet-printer deposition of biomolecular components in microarrays across the surface of silicon chips. We demonstrate clinical feasibility by characterizing the compositional phenotype of human skin fibroblast and porcine alveolar macrophage cell populations in the respective contexts of Niemann-Pick disease and drug-induced phospholipidosis: two types of lipid storage disorders. We envision this microanalytical platform as the foundation for many future biomedical applications, ranging from diagnostic assays to pathological analysis to advanced pharmaco/toxicokinetic research studies.
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Affiliation(s)
- Vernon LaLone
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Maria V Fawaz
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jomar Morales-Mercado
- School of Sciences, Technology, and Environment, Universidad Ana G. Méndez Cupey Campus, San Juan, Puerto Rico
| | - Márcio A Mourão
- CSCAR Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Catherine S Snyder
- Department of Materials Science and Engineering, College of Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sang Yeop Kim
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Andrew P Lieberman
- Department of Pathology, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
| | - Anish Tuteja
- Department of Materials Science and Engineering, College of Engineering, University of Michigan, Ann Arbor, MI 48109, USA and Biointerfaces Institute, Macromolecular Science and Engineering, Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Geeta Mehta
- Department of Materials Science and Engineering, College of Engineering, University of Michigan, Ann Arbor, MI 48109, USA and Department of Biomedical Engineering, Macromolecular Science and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Theodore J Standiford
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
| | - Krishnan Raghavendran
- Department of Surgery, Michigan Medicine, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
| | - Kerby Shedden
- CSCAR Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Anna Schwendeman
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Kathleen A Stringer
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI 48109, USA and Department of Clinical Pharmacy, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA
| | - Gus R Rosania
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA.
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15
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Bryant D, Liu Y, Datta S, Hariri H, Seda M, Anderson G, Peskett E, Demetriou C, Sousa S, Jenkins D, Clayton P, Bitner-Glindzicz M, Moore GE, Henne WM, Stanier P. SNX14 mutations affect endoplasmic reticulum-associated neutral lipid metabolism in autosomal recessive spinocerebellar ataxia 20. Hum Mol Genet 2019; 27:1927-1940. [PMID: 29635513 DOI: 10.1093/hmg/ddy101] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/15/2018] [Indexed: 12/12/2022] Open
Abstract
Mutations in SNX14 cause the autosomal recessive cerebellar ataxia 20 (SCAR20). Mutations generally result in loss of protein although several coding region deletions have also been reported. Patient-derived fibroblasts show disrupted autophagy, but the precise function of SNX14 is unknown. The yeast homolog, Mdm1, functions in endoplasmic reticulum (ER)-lysosome/vacuole inter-organelle tethering, but functional conservation in mammals is still required. Here, we show that loss of SNX14 alters but does not block autophagic flux. In addition, we find that SNX14 is an ER-associated protein that functions in neutral lipid homeostasis and inter-organelle crosstalk. SNX14 requires its N-terminal transmembrane helices for ER localization, while the Phox homology (PX) domain is dispensable for subcellular localization. Both SNX14-mutant fibroblasts and SNX14KO HEK293 cells accumulate aberrant cytoplasmic vacuoles, suggesting defects in endolysosomal homeostasis. However, ER-late endosome/lysosome contact sites are maintained in SNX14KO cells, indicating that it is not a prerequisite for ER-endolysosomal tethering. Further investigation of SNX14- deficiency indicates general defects in neutral lipid metabolism. SNX14KO cells display distinct perinuclear accumulation of filipin in LAMP1-positive lysosomal structures indicating cholesterol accumulation. Consistent with this, SNX14KO cells display a slight but detectable decrease in cholesterol ester levels, which is exacerbated with U18666A. Finally, SNX14 associates with ER-derived lipid droplets (LD) following oleate treatment, indicating a role in ER-LD crosstalk. We therefore identify an important role for SNX14 in neutral lipid homeostasis between the ER, lysosomes and LDs that may provide an early intervention target to alleviate the clinical symptoms of SCAR20.
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Affiliation(s)
- Dale Bryant
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Yang Liu
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sanchari Datta
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Hanaa Hariri
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Marian Seda
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Glenn Anderson
- Histopathology Department, Great Ormond Street Hospital, London WC1N 3JH, UK
| | - Emma Peskett
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Charalambos Demetriou
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Sergio Sousa
- Serviço de Genética Medica, Hospital Pediatrico, Centro Hospitalar e Universitário de Coimbra, 3000-602 Coimbra, Portugal
| | - Dagan Jenkins
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Peter Clayton
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Maria Bitner-Glindzicz
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Gudrun E Moore
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Philip Stanier
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
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16
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Wei X, Nishi T, Kondou S, Kimura H, Mody I. Preferential enhancement of GluN2B-containing native NMDA receptors by the endogenous modulator 24S-hydroxycholesterol in hippocampal neurons. Neuropharmacology 2018; 148:11-20. [PMID: 30594698 DOI: 10.1016/j.neuropharm.2018.12.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/11/2018] [Accepted: 12/26/2018] [Indexed: 11/24/2022]
Abstract
24S-hydroxycholesterol (24HC) is the major metabolic breakdown product of cholesterol in the brain. Among its other effects on neurons, 24HC modulates N-methyl-d-aspartate (NMDA or GluN) receptors, but our understanding of this mechanism is poor. We used whole-cell patch clamp recordings and various pharmacological approaches in mouse brain slices to record isolated NMDAR-mediated (INMDA) tonic and evoked synaptic currents. 24HC (1 μΜ) significantly enhanced tonic, but not evoked, INMDA of dentate gyrus granule cells. The INMDA had both GluN2A and GluN2B-mediated components. Preincubation of the slices with PEAQX (a GluN2A antagonist) or Ro25-6981 (a GluN2B antagonist) dramatically changed the INMDA modulatory potential of 24HC. Ro25-6981 blocked the enhancing effect of 24HC on tonic INMDA, while preincubation with PEAQX had no effect. In cholesterol 24-hydroxylase (CYP46A1) knockout mice, in sharp contrast to WT, 24HC slightly decreased the tonic INMDA of granule cells. Furthermore, 24HC had no effect on tonic INMDA of dentate gyrus parvalbumin interneurons (PV-INs), known to express different GluN subunits than granule cells. Taken together, our results revealed a specific enhancement of GluN2B-containing NMDARs by 24HC, indicating a novel endogenous pathway to influence a subclass of NMDARs critically involved in cortical plasticity and in numerous neurological and psychiatric disorders.
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Affiliation(s)
- Xiaofei Wei
- Department of Neurology, The David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA
| | - Toshiya Nishi
- Department of Physiology, The David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA
| | - Shinichi Kondou
- Department of Physiology, The David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA
| | - Haruhide Kimura
- Department of Physiology, The David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA
| | - Istvan Mody
- Department of Neurology, The David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA; Research, Takeda Pharmaceutical Company Ltd, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-8555, Japan.
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17
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Coordinate regulation of mutant NPC1 degradation by selective ER autophagy and MARCH6-dependent ERAD. Nat Commun 2018; 9:3671. [PMID: 30202070 PMCID: PMC6131187 DOI: 10.1038/s41467-018-06115-2] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 07/26/2018] [Indexed: 12/30/2022] Open
Abstract
Niemann–Pick type C disease is a fatal, progressive neurodegenerative disorder caused by loss-of-function mutations in NPC1, a multipass transmembrane glycoprotein essential for intracellular lipid trafficking. We sought to define the cellular machinery controlling degradation of the most common disease-causing mutant, I1061T NPC1. We show that this mutant is degraded, in part, by the proteasome following MARCH6-dependent ERAD. Unexpectedly, we demonstrate that I1061T NPC1 is also degraded by a recently described autophagic pathway called selective ER autophagy (ER-phagy). We establish the importance of ER-phagy both in vitro and in vivo, and identify I1061T as a misfolded endogenous substrate for this FAM134B-dependent process. Subcellular fractionation of I1061T Npc1 mouse tissues and analysis of human samples show alterations of key components of ER-phagy, including FAM134B. Our data establish that I1061T NPC1 is recognized in the ER and degraded by two different pathways that function in a complementary fashion to regulate protein turnover. Niemann-Pick type C1 disease is most commonly caused by the allele NPC1 I1061T, which is misfolded in the ER and rapidly degraded by the ubiquitin proteasome system. Here the authors show that the I1061T mutant is also degraded by ER-phagy.
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18
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Lamri A, Pigeyre M, Garver WS, Meyre D. The Extending Spectrum of NPC1-Related Human Disorders: From Niemann-Pick C1 Disease to Obesity. Endocr Rev 2018; 39:192-220. [PMID: 29325023 PMCID: PMC5888214 DOI: 10.1210/er.2017-00176] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 01/02/2018] [Indexed: 12/22/2022]
Abstract
The Niemann-Pick type C1 (NPC1) protein regulates the transport of cholesterol and fatty acids from late endosomes/lysosomes and has a central role in maintaining lipid homeostasis. NPC1 loss-of-function mutations in humans cause NPC1 disease, a rare autosomal-recessive lipid-storage disorder characterized by progressive and lethal neurodegeneration, as well as liver and lung failure, due to cholesterol infiltration. In humans, genome-wide association studies and post-genome-wide association studies highlight the implication of common variants in NPC1 in adult-onset obesity, body fat mass, and type 2 diabetes. Heterozygous human carriers of rare loss-of-function coding variants in NPC1 display an increased risk of morbid adult obesity. These associations have been confirmed in mice models, showing an important interaction with high-fat diet. In this review, we describe the current state of knowledge for NPC1 variants in relationship to pleiotropic effects on metabolism. We provide evidence that NPC1 gene variations may predispose to common metabolic diseases by modulating steroid hormone synthesis and/or lipid homeostasis. We also propose several important directions of research to further define the complex roles of NPC1 in metabolism. This review emphasizes the contribution of NPC1 to obesity and its metabolic complications.
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Affiliation(s)
- Amel Lamri
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada
| | - Marie Pigeyre
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada.,INSERM 1190, European Genomics Institute for Diabetes, University of Lille, CHRU Lille, Lille, France
| | - William S Garver
- Department of Biochemistry and Molecular Biology, School of Medicine, University of New Mexico, Albuquerque, New Mexico
| | - David Meyre
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada.,Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
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19
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Peter F, Rost S, Rolfs A, Frech MJ. Activation of PKC triggers rescue of NPC1 patient specific iPSC derived glial cells from gliosis. Orphanet J Rare Dis 2017; 12:145. [PMID: 28841900 PMCID: PMC5574080 DOI: 10.1186/s13023-017-0697-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 08/20/2017] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Niemann-Pick disease Type C1 (NPC1) is a rare progressive neurodegenerative disorder caused by mutations in the NPC1 gene. The pathological mechanisms, underlying NPC1 are not yet completely understood. Especially the contribution of glial cells and gliosis to the progression of NPC1, are controversially discussed. As an analysis of affected cells is unfeasible in NPC1-patients, we recently developed an in vitro model system, based on cells derived from NPC1-patient specific iPSCs. Here, we asked if this model system recapitulates gliosis, observed in non-human model systems and NPC1 patient post mortem biopsies. We determined the amount of reactive astrocytes and the regulation of the intermediate filaments GFAP and vimentin, all indicating gliosis. Furthermore, we were interested in the assembly and phosphorylation of these intermediate filaments and finally the impact of the activation of protein kinase C (PKC), which is described to ameliorate the pathogenic phenotype of NPC1-deficient fibroblasts, including hypo-phosphorylation of vimentin and cholesterol accumulation. METHODS We analysed glial cells derived from NPC1 patient specific induced pluripotent stem cells, carrying different NPC1 mutations. The amount of reactive astrocytes was determined by means of immuncytochemical stainings and FACS-analysis. Semi-quantitative western blot was used to determine the amount of phosphorylated GFAP and vimentin. Cholesterol accumulation was analysed by Filipin staining and quantified by Amplex Red Assay. U18666A was used to induce NPC1 phenotype in unaffected cells of the control cell line. Phorbol 12-myristate 13-acetate (PMA) was used to activate PKC. RESULTS Immunocytochemical detection of GFAP, vimentin and Ki67 revealed that NPC1 mutant glial cells undergo gliosis. We found hypo-phosphorylation of the intermediate filaments GFAP and vimentin and alterations in the assembly of these intermediate filaments in NPC1 mutant cells. The application of U18666A induced not only NPC1 phenotypical accumulation of cholesterol, but characteristics of gliosis in glial cells derived from unaffected control cells. The application of phorbol 12-myristate 13-acetate, an activator of protein kinase C resulted in a significantly reduced number of reactive astrocytes and further characteristics of gliosis in NPC1-deficient cells. Furthermore, it triggered a restoration of cholesterol amounts to level of control cells. CONCLUSION Our data demonstrate that glial cells derived from NPC1-patient specific iPSCs undergo gliosis. The application of U18666A induced comparable characteristics in un-affected control cells, suggesting that gliosis is triggered by hampered function of NPC1 protein. The activation of protein kinase C induced an amelioration of gliosis, as well as a reduction of cholesterol amount. These results provide further support for the line of evidence that gliosis might not be only a secondary reaction to the loss of neurons, but might be a direct consequence of a reduced PKC activity due to the phenotypical cholesterol accumulation observed in NPC1. In addition, our data support the involvement of PKCs in NPC1 disease pathogenesis and suggest that PKCs may be targeted in future efforts to develop therapeutics for NPC1 disease.
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Affiliation(s)
- Franziska Peter
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University Medicine Rostock, Gehlsheimer Straße 20, 18147 Rostock, Germany
| | - Sebastian Rost
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University Medicine Rostock, Gehlsheimer Straße 20, 18147 Rostock, Germany
| | - Arndt Rolfs
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University Medicine Rostock, Gehlsheimer Straße 20, 18147 Rostock, Germany
| | - Moritz J. Frech
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University Medicine Rostock, Gehlsheimer Straße 20, 18147 Rostock, Germany
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20
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Probert F, Ruiz-Rodado V, Vruchte DT, Nicoli ER, Claridge TDW, Wassif CA, Farhat N, Porter FD, Platt FM, Grootveld M. NMR analysis reveals significant differences in the plasma metabolic profiles of Niemann Pick C1 patients, heterozygous carriers, and healthy controls. Sci Rep 2017; 7:6320. [PMID: 28740230 PMCID: PMC5524790 DOI: 10.1038/s41598-017-06264-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 06/09/2017] [Indexed: 02/07/2023] Open
Abstract
Niemann-Pick type C1 (NPC1) disease is a rare autosomal recessive, neurodegenerative lysosomal storage disorder, which presents with a range of clinical phenotypes and hence diagnosis remains a challenge. In view of these difficulties, the search for a novel, NPC1-specific biomarker (or set of biomarkers) is a topic of much interest. Here we employed high-resolution 1H nuclear magnetic resonance spectroscopy coupled with advanced multivariate analysis techniques in order to explore and seek differences between blood plasma samples acquired from NPC1 (untreated and miglustat treated), heterozygote, and healthy control subjects. Using this approach, we were able to identify NPC1 disease with 91% accuracy confirming that there are significant differences in the NMR plasma metabolic profiles of NPC1 patients when compared to healthy controls. The discrimination between NPC1 (both miglustat treated and untreated) and healthy controls was dominated by lipoprotein triacylglycerol 1H NMR resonances and isoleucine. Heterozygote plasma samples displayed also increases in the intensities of selected lipoprotein triacylglycerol 1H NMR signals over those of healthy controls. The metabolites identified could represent useful biomarkers in the future and provide valuable insight in to the underlying pathology of NPC1 disease.
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Affiliation(s)
- Fay Probert
- Department of Pharmacology, De Montfort University, Leicester, UK.,Department of Pharmacology, University of Oxford, Oxford, UK
| | | | | | | | | | - Christopher A Wassif
- Department of Pharmacology, University of Oxford, Oxford, UK.,Section of Molecular Dysmorphology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institute of Health, Department of Health and Human Services, Bethesda, MD, USA
| | - Nicole Farhat
- Section of Molecular Dysmorphology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institute of Health, Department of Health and Human Services, Bethesda, MD, USA
| | - Forbes D Porter
- Section of Molecular Dysmorphology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institute of Health, Department of Health and Human Services, Bethesda, MD, USA
| | - Frances M Platt
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Martin Grootveld
- Department of Pharmacology, De Montfort University, Leicester, UK.
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21
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De Castro-Orós I, Irún P, Cebolla JJ, Rodriguez-Sureda V, Mallén M, Pueyo MJ, Mozas P, Dominguez C, Pocoví M. Assessment of plasma chitotriosidase activity, CCL18/PARC concentration and NP-C suspicion index in the diagnosis of Niemann-Pick disease type C: a prospective observational study. J Transl Med 2017; 15:43. [PMID: 28222799 PMCID: PMC5320753 DOI: 10.1186/s12967-017-1146-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 02/09/2017] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Niemann-Pick disease type C (NP-C) is a rare, autosomal recessive neurodegenerative disease caused by mutations in either the NPC1 or NPC2 genes. The diagnosis of NP-C remains challenging due to the non-specific, heterogeneous nature of signs/symptoms. This study assessed the utility of plasma chitotriosidase (ChT) and Chemokine (C-C motif) ligand 18 (CCL18)/pulmonary and activation-regulated chemokine (PARC) in conjunction with the NP-C suspicion index (NP-C SI) for guiding confirmatory laboratory testing in patients with suspected NP-C. METHODS In a prospective observational cohort study, incorporating a retrospective determination of NP-C SI scores, two different diagnostic approaches were applied in two separate groups of unrelated patients from 51 Spanish medical centers (n = 118 in both groups). From Jan 2010 to Apr 2012 (Period 1), patients with ≥2 clinical signs/symptoms of NP-C were considered 'suspected NP-C' cases, and NPC1/NPC2 sequencing, plasma chitotriosidase (ChT), CCL18/PARC and sphingomyelinase levels were assessed. Based on findings in Period 1, plasma ChT and CCL18/PARC, and NP-C SI prediction scores were determined in a second group of patients between May 2012 and Apr 2014 (Period 2), and NPC1 and NPC2 were sequenced only in those with elevated ChT and/or elevated CCL18/PARC and/or NP-C SI ≥70. Filipin staining and 7-ketocholesterol (7-KC) measurements were performed in all patients with NP-C gene mutations, where possible. RESULTS In total across Periods 1 and 2, 10/236 (4%) patients had a confirmed diagnosis o NP-C based on gene sequencing (5/118 [4.2%] in each Period): all of these patients had two causal NPC1 mutations. Single mutant NPC1 alleles were detected in 8/236 (3%) patients, overall. Positive filipin staining results comprised three classical and five variant biochemical phenotypes. No NPC2 mutations were detected. All patients with NPC1 mutations had high ChT activity, high CCL18/PARC concentrations and/or NP-C SI scores ≥70. Plasma 7-KC was higher than control cut-off values in all patients with two NPC1 mutations, and in the majority of patients with single mutations. Family studies identified three further NP-C patients. CONCLUSION This approach may be very useful for laboratories that do not have mass spectrometry facilities and therefore, they cannot use other NP-C biomarkers for diagnosis.
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Affiliation(s)
- Isabel De Castro-Orós
- Department of Biochemistry and Molecular and Cellular Biology, Faculty of Science, University of Zaragoza, C. Pedro Cerbuna 12, 50009, Saragossa, Spain. .,Instituto de Investigación Sanitaria Aragón (IIS Aragón), Saragossa, Spain.
| | - Pilar Irún
- Department of Biochemistry and Molecular and Cellular Biology, Faculty of Science, University of Zaragoza, C. Pedro Cerbuna 12, 50009, Saragossa, Spain.,Instituto de Investigación Sanitaria Aragón (IIS Aragón), Saragossa, Spain.,Centro de Investigación Biomédica en Red (CIBERER), Instituto de Salud Carlos III, Saragossa, Spain
| | - Jorge Javier Cebolla
- Department of Biochemistry and Molecular and Cellular Biology, Faculty of Science, University of Zaragoza, C. Pedro Cerbuna 12, 50009, Saragossa, Spain.,Spanish Foundation for the Study and Therapy of Gaucher Disease, Saragossa, Spain
| | - Victor Rodriguez-Sureda
- Centro de Investigación Biomédica en Red (CIBERER), Instituto de Salud Carlos III, Saragossa, Spain.,Biochemistry and Molecular Biology Research Centre for Nanomedicine, Vall d'Hebron University Hospital, Barcelona, Spain
| | - Miguel Mallén
- Department of Biochemistry and Molecular and Cellular Biology, Faculty of Science, University of Zaragoza, C. Pedro Cerbuna 12, 50009, Saragossa, Spain
| | - María Jesús Pueyo
- Department of Biochemistry and Molecular and Cellular Biology, Faculty of Science, University of Zaragoza, C. Pedro Cerbuna 12, 50009, Saragossa, Spain
| | - Pilar Mozas
- Department of Biochemistry and Molecular and Cellular Biology, Faculty of Science, University of Zaragoza, C. Pedro Cerbuna 12, 50009, Saragossa, Spain
| | - Carmen Dominguez
- Centro de Investigación Biomédica en Red (CIBERER), Instituto de Salud Carlos III, Saragossa, Spain.,Biochemistry and Molecular Biology Research Centre for Nanomedicine, Vall d'Hebron University Hospital, Barcelona, Spain
| | - Miguel Pocoví
- Department of Biochemistry and Molecular and Cellular Biology, Faculty of Science, University of Zaragoza, C. Pedro Cerbuna 12, 50009, Saragossa, Spain.,Instituto de Investigación Sanitaria Aragón (IIS Aragón), Saragossa, Spain
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22
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Ebrahimi-Fakhari D, Wahlster L, Bartz F, Werenbeck-Ueding J, Praggastis M, Zhang J, Joggerst-Thomalla B, Theiss S, Grimm D, Ory DS, Runz H. Reduction of TMEM97 increases NPC1 protein levels and restores cholesterol trafficking in Niemann-pick type C1 disease cells. Hum Mol Genet 2016; 25:3588-3599. [PMID: 27378690 PMCID: PMC5179952 DOI: 10.1093/hmg/ddw204] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 06/15/2016] [Accepted: 06/16/2016] [Indexed: 02/07/2023] Open
Abstract
Niemann-Pick type C disease (NP-C) is a progressive lysosomal lipid storage disease caused by mutations in the NPC1 and NPC2 genes. NPC1 is essential for transporting cholesterol and other lipids out of lysosomes, but little is known about the mechanisms that control its cellular abundance and localization. Here we show that a reduction of TMEM97, a cholesterol-responsive NPC1-binding protein, increases NPC1 levels in cells through a post-transcriptional mechanism. Reducing TMEM97 through RNA-interference reduces lysosomal lipid storage and restores cholesterol trafficking to the endoplasmic reticulum in cell models of NP-C. In TMEM97 knockdown cells, NPC1 levels can be reinstated with wild type TMEM97, but not TMEM97 missing an ER-retention signal suggesting that TMEM97 contributes to controlling the availability of NPC1 to the cell. Importantly, knockdown of TMEM97 also increases levels of residual NPC1 in NPC1-mutant patient fibroblasts and reduces cholesterol storage in an NPC1-dependent manner. Our findings propose TMEM97 inhibition as a novel strategy to increase residual NPC1 levels in cells and a potential therapeutic target for NP-C.
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Affiliation(s)
- Darius Ebrahimi-Fakhari
- Institute of Human Genetics, Ruprecht-Karls-University Heidelberg
- Division of Pediatric Neurology and Metabolic Medicine, Department of Pediatrics, Heidelberg University Hospital, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
| | - Lara Wahlster
- Institute of Human Genetics, Ruprecht-Karls-University Heidelberg
- Division of Pediatric Neurology and Metabolic Medicine, Department of Pediatrics, Heidelberg University Hospital, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany
| | - Fabian Bartz
- Institute of Human Genetics, Ruprecht-Karls-University Heidelberg
| | | | - Maria Praggastis
- Diabetic Cardiovascular Disease Center and Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Jessie Zhang
- Diabetic Cardiovascular Disease Center and Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Susanne Theiss
- Institute of Human Genetics, Ruprecht-Karls-University Heidelberg
| | - Dirk Grimm
- Center for Infectious Diseases/Virology, BioQuant BQ0030, Heidelberg, Germany
| | - Daniel S Ory
- Diabetic Cardiovascular Disease Center and Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Heiko Runz
- Institute of Human Genetics, Ruprecht-Karls-University Heidelberg
- Molecular Medicine Partnership Unit (MMPU), Ruprecht-Karls-University Heidelberg/European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
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23
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Vanier MT, Gissen P, Bauer P, Coll MJ, Burlina A, Hendriksz CJ, Latour P, Goizet C, Welford RWD, Marquardt T, Kolb SA. Diagnostic tests for Niemann-Pick disease type C (NP-C): A critical review. Mol Genet Metab 2016; 118:244-54. [PMID: 27339554 DOI: 10.1016/j.ymgme.2016.06.004] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 06/03/2016] [Accepted: 06/03/2016] [Indexed: 12/14/2022]
Abstract
Niemann-Pick disease type C (NP-C) is a neurovisceral lysosomal cholesterol trafficking and lipid storage disorder caused by mutations in one of the two genes, NPC1 or NPC2. Diagnosis has often been a difficult task, due to the wide range in age of onset of NP-C and clinical presentation of the disease, combined with the complexity of the cell biology (filipin) laboratory testing, even in combination with genetic testing. This has led to substantial delays in diagnosis, largely depending on the access to specialist centres and the level of knowledge about NP-C of the physician in the area. In recent years, advances in mass spectrometry has allowed identification of several sensitive plasma biomarkers elevated in NP-C (e.g. cholestane-3β,5α,6β-triol, lysosphingomyelin isoforms and bile acid metabolites), which, together with the concomitant progress in molecular genetic technology, have greatly impacted the strategy of laboratory testing. Specificity of the biomarkers is currently under investigation and other pathologies are being found to also result in elevations. Molecular genetic testing also has its limitations, notably with unidentified mutations and the classification of new variants. This review is intended to increase awareness on the currently available approaches to laboratory diagnosis of NP-C, to provide an up to date, comprehensive and critical evaluation of the various techniques (cell biology, biochemical biomarkers and molecular genetics), and to briefly discuss ongoing/future developments. The use of current tests in proper combination enables a rapid and correct diagnosis in a large majority of cases. However, even with recent progress, definitive diagnosis remains challenging in some patients, for whom combined genetic/biochemical/cytochemical markers do not provide a clear answer. Expertise and reference laboratories thus remain essential, and further work is still required to fulfill unmet needs.
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Affiliation(s)
- Marie T Vanier
- INSERM Unit 820, 7 Rue Guillaume Paradin, 69008 Lyon, France; Laboratoire Gillet-Mérieux, Centre de Biologie et Pathologie Est, Hospices Civils de Lyon, 69500 Bron, France.
| | - Paul Gissen
- UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK; Great Ormond Street Hospital, London WC1N 3JH, UK.
| | - Peter Bauer
- Institute of Medical Genetics and Applied Genomics, University Hospital of Tübingen, 72076 Tübingen, Germany.
| | - Maria J Coll
- Inborn Errors of Metabolism Section, Biochemistry and Molecular Genetics Service, Hospital Clínic of Barcelona, 08036 Barcelona, Spain; CIBERER, Spain.
| | - Alberto Burlina
- Division of Inherited Metabolic Diseases, Department of Pediatrics, University Hospital, 35129 Padova, Italy.
| | - Christian J Hendriksz
- The Mark Holland Metabolic Unit, Salford Royal Foundation NHS Trust, Salford, Manchester M68HD, UK; University of Pretoria, Steve Biko Academic Hospital, Department of Paediatrics and Child Health, Pretoria 0001, South Africa.
| | - Philippe Latour
- UF de Neurogénétique Moléculaire, Centre de Biologie et Pathologie Est, Hospices Civils de Lyon, 69500 Bron, France.
| | - Cyril Goizet
- CHU Bordeaux, Department of Medical Genetics, 33076 Bordeaux, France; INSERM Unit 1211, University of Bordeaux, 33076 Bordeaux, France.
| | - Richard W D Welford
- Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, 4123 Allschwil, Switzerland.
| | - Thorsten Marquardt
- Unit for Inborn Errors of Metabolism, University Hospital Münster, 48149 Münster, Germany.
| | - Stefan A Kolb
- Actelion Pharmaceuticals Ltd., Gewerbestrasse 16, 4123 Allschwil, Switzerland.
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24
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Guo H, Zhao M, Qiu X, Deis JA, Huang H, Tang QQ, Chen X. Niemann-Pick type C2 deficiency impairs autophagy-lysosomal activity, mitochondrial function, and TLR signaling in adipocytes. J Lipid Res 2016; 57:1644-58. [PMID: 27402802 DOI: 10.1194/jlr.m066522] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Indexed: 12/26/2022] Open
Abstract
In this study, we investigated the role and mechanism of Niemann-Pick type C (NPC)2 in regulating lysosomal activity, mitophagy, and mitochondrial function in adipocytes. We found that knocking down NPC2 impaired lysosomal activity, as evidenced by the reduced mature cathepsin B, the increased accumulation of light chain 3 (LC3) and p62, and the decreased autophagic flux. In NPC2-knockdown (kd) adipocytes, the starvation-induced conversion of LC3-I to LC3-II was abolished. More interestingly, the majority of NPC2 was found in the mitochondrial fraction, and NPC2 deficiency led to impaired autophagic flux and decreased induction of LC3-II in the mitochondrial fraction during mitochondrial stress. Moreover, cellular respiration profiling revealed that NPC2-kd adipocytes had significantly decreased basal/maximal respiration and mitochondrial gene expression compared with scrambled cells, suggesting mitochondrial dysfunction. Additionally, we found that the mitochondrial recruitment of LC3-II induced by lipopolysaccharide (LPS), but not TNFα, was blunted in NPC2-kd adipocytes. Most intriguingly, NPC2-kd selectively diminished LPS-induced NFκB and ERK1/2 phosphorylation and the expression of pro-inflammatory genes, indicating that toll-like receptor signaling activation is impaired in the absence of NPC2. Our results suggest that NPC2 is in a mitochondrially associated autophagosome and plays an important role in regulating mitophagy, mitochondrial quality control, and mitochondrial function.
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Affiliation(s)
- Hong Guo
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN
| | - Ming Zhao
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN
| | - Xiaoxue Qiu
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN
| | - Jessica A Deis
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN
| | - Haiyan Huang
- Key Laboratory of Metabolism and Molecular Medicine and Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai, China
| | - Qi-Qun Tang
- Key Laboratory of Metabolism and Molecular Medicine and Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai, China
| | - Xiaoli Chen
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, MN
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25
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Sadananda SN, Foo JN, Toh MT, Cermakova L, Trigueros-Motos L, Chan T, Liany H, Collins JA, Gerami S, Singaraja RR, Hayden MR, Francis GA, Frohlich J, Khor CC, Brunham LR. Targeted next-generation sequencing to diagnose disorders of HDL cholesterol. J Lipid Res 2015; 56:1993-2001. [PMID: 26255038 DOI: 10.1194/jlr.p058891] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Indexed: 01/01/2023] Open
Abstract
A low level of HDL cholesterol (HDL-C) is a common clinical scenario and an important marker for increased cardiovascular risk. Many patients with very low or very high HDL-C have a rare mutation in one of several genes, but identification of the molecular abnormality in patients with extreme HDL-C is rarely performed in clinical practice. We investigated the accuracy and diagnostic yield of a targeted next-generation sequencing (NGS) assay for extreme levels of HDL-C. We developed a targeted NGS panel to capture the exons, intron/exon boundaries, and untranslated regions of 26 genes with highly penetrant effects on plasma lipid levels. We sequenced 141 patients with extreme HDL-C levels and prioritized variants in accordance with medical genetics guidelines. We identified 35 pathogenic and probably pathogenic variants in HDL genes, including 21 novel variants, and performed functional validation on a subset of these. Overall, a molecular diagnosis was established in 35.9% of patients with low HDL-C and 5.2% with high HDL-C, and all prioritized variants identified by NGS were confirmed by Sanger sequencing. Our results suggest that a molecular diagnosis can be identified in a substantial proportion of patients with low HDL-C using targeted NGS.
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Affiliation(s)
- Singh N Sadananda
- Translational Laboratory in Genetic Medicine, Agency for Science Technology and Research (ASTAR) and National University of Singapore, Singapore
| | - Jia Nee Foo
- Human Genetics, Genome Institute of Singapore, Agency for Science Technology and Research (ASTAR), Singapore
| | - Meng Tiak Toh
- Translational Laboratory in Genetic Medicine, Agency for Science Technology and Research (ASTAR) and National University of Singapore, Singapore
| | - Lubomira Cermakova
- Healthy Heart Program Prevention Clinic, St. Paul's Hospital, Vancouver, Canada
| | - Laia Trigueros-Motos
- Translational Laboratory in Genetic Medicine, Agency for Science Technology and Research (ASTAR) and National University of Singapore, Singapore
| | - Teddy Chan
- Centre for Heart Lung Innovation, University of British Columbia, Vancouver, Canada
| | - Herty Liany
- Human Genetics, Genome Institute of Singapore, Agency for Science Technology and Research (ASTAR), Singapore
| | - Jennifer A Collins
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, Canada
| | - Sima Gerami
- Healthy Heart Program Prevention Clinic, St. Paul's Hospital, Vancouver, Canada
| | - Roshni R Singaraja
- Translational Laboratory in Genetic Medicine, Agency for Science Technology and Research (ASTAR) and National University of Singapore, Singapore
| | - Michael R Hayden
- Translational Laboratory in Genetic Medicine, Agency for Science Technology and Research (ASTAR) and National University of Singapore, Singapore Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, Canada Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Gordon A Francis
- Healthy Heart Program Prevention Clinic, St. Paul's Hospital, Vancouver, Canada Centre for Heart Lung Innovation, University of British Columbia, Vancouver, Canada Departments of Medicine University of British Columbia, Vancouver, Canada
| | - Jiri Frohlich
- Healthy Heart Program Prevention Clinic, St. Paul's Hospital, Vancouver, Canada Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada
| | - Chiea Chuen Khor
- Human Genetics, Genome Institute of Singapore, Agency for Science Technology and Research (ASTAR), Singapore
| | - Liam R Brunham
- Translational Laboratory in Genetic Medicine, Agency for Science Technology and Research (ASTAR) and National University of Singapore, Singapore Healthy Heart Program Prevention Clinic, St. Paul's Hospital, Vancouver, Canada Centre for Heart Lung Innovation, University of British Columbia, Vancouver, Canada Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore Departments of Medicine University of British Columbia, Vancouver, Canada
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26
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Rauniyar N, Subramanian K, Lavallée-Adam M, Martínez-Bartolomé S, Balch WE, Yates JR. Quantitative Proteomics of Human Fibroblasts with I1061T Mutation in Niemann-Pick C1 (NPC1) Protein Provides Insights into the Disease Pathogenesis. Mol Cell Proteomics 2015; 14:1734-49. [PMID: 25873482 DOI: 10.1074/mcp.m114.045609] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Indexed: 11/06/2022] Open
Abstract
Niemann-Pick type C (NPC) disease is a fatal neurodegenerative disorder characterized by the accumulation of unesterified cholesterol in the late endosomal/lysosomal compartments. Mutations in the NPC1 protein are implicated in 95% of patients with NPC disease. The most prevalent mutation is the missense mutation I1061T that occurs in ∼ 15-20% of the disease alleles. In our study, an isobaric labeling-based quantitative analysis of proteome of NPC1(I1061T) primary fibroblasts when compared with wild-type cells identified 281 differentially expressed proteins based on stringent data analysis criteria. Gene ontology enrichment analysis revealed that these proteins play important roles in diverse cellular processes such as protein maturation, energy metabolism, metabolism of reactive oxygen species, antioxidant activity, steroid metabolism, lipid localization, and apoptosis. The relative expression level of a subset of differentially expressed proteins (TOR4A, DHCR24, CLGN, SOD2, CHORDC1, HSPB7, and GAA) was independently and successfully substantiated by Western blotting. We observed that treating NPC1(I1061T) cells with four classes of seven different compounds that are potential NPC drugs increased the expression level of SOD2 and DHCR24. We have also shown an abnormal accumulation of glycogen in NPC1(I1061T) fibroblasts possibly triggered by defective processing of lysosomal alpha-glucosidase. Our study provides a starting point for future more focused investigations to better understand the mechanisms by which the reported dysregulated proteins triggers the pathological cascade in NPC, and furthermore, their effect upon therapeutic interventions.
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Affiliation(s)
| | - Kanagaraj Subramanian
- §Department of Cell and Molecular Biology, The Scripps Research Institute, 10550, North Torrey Pines Road, La Jolla, California-92037
| | | | | | - William E Balch
- §Department of Cell and Molecular Biology, The Scripps Research Institute, 10550, North Torrey Pines Road, La Jolla, California-92037.
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27
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Wassif CA, Cross JL, Iben J, Sanchez-Pulido L, Cougnoux A, Platt FM, Ory DS, Ponting CP, Bailey-Wilson JE, Biesecker LG, Porter FD. High incidence of unrecognized visceral/neurological late-onset Niemann-Pick disease, type C1, predicted by analysis of massively parallel sequencing data sets. Genet Med 2015; 18:41-8. [PMID: 25764212 PMCID: PMC4486368 DOI: 10.1038/gim.2015.25] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Accepted: 01/21/2015] [Indexed: 11/20/2022] Open
Abstract
Purpose Niemann-Pick disease, type C (NPC) is a recessive, neurodegenerative, lysosomal storage disease caused by mutations in either NPC1 or NPC2. The diagnosis is difficult and frequently delayed. Ascertainment is likely incomplete due to both these factors and that the full phenotypic spectrum may not have been fully delineated. Given the recent development of a blood-based diagnostic test and development of potential therapies, it is important to understand the incidence of NPC and to define at risk patient populations. Method We evaluated data from four large massively parallel exome sequencing data sets. Variant sequences were identified and classified as pathogenic or non-pathogenic based on a combination of literature review and bioinformatic analysis. This methodology provided an unbiased approach to determining the allele frequency. Results Our data suggests an incidence rate for NPC1 and NPC2 of 1/92,104 and 1/2,858,998, respectively. However, evaluation of common NPC1 variants, suggests that there may be a late-onset NPC1phenotype with a markedly higher incidence on the order of 1/20,000-39,000. Conclusions We determined a combined incidence of classical NPC of 1/89,229 or 1.12 affected patients per 100,000 conceptions, but predict incomplete ascertainment of a late-onset phenotype of NPC1. This finding strongly supports the need for increased screening of potential patients.
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Affiliation(s)
- Christopher A Wassif
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA.,Department of Pharmacology, University of Oxford, Oxford, UK
| | - Joanna L Cross
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA.,Department of Pharmacology, University of Oxford, Oxford, UK
| | - James Iben
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Luis Sanchez-Pulido
- Department of Physiology, Anatomy and Genetics, MRC Functional Genomics Unit, University of Oxford, Oxford, UK
| | - Antony Cougnoux
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Frances M Platt
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Daniel S Ory
- Diabetic Cardiovascular Disease Center, Washington University School of Medicine, St Louis, Missouri, USA
| | - Chris P Ponting
- Department of Physiology, Anatomy and Genetics, MRC Functional Genomics Unit, University of Oxford, Oxford, UK
| | - Joan E Bailey-Wilson
- Statistical Genetics Section, Computational and Statistical Genomics Branch, National Human Genome Research Institute, National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Leslie G Biesecker
- Clinical Genomics Section, National Human Genome Research Institute, National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Forbes D Porter
- Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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Santos DC, da Silva Garcia C, de Andrade CV, Daitx VV, da Costa Moraes V, Rohden F, Coelho JC. Effect of u18666a on beta-glucosidase, sphingomyelinase, and beta-galactosidase activities in astrocytes of young rats. J Membr Biol 2015; 248:215-22. [PMID: 25688009 DOI: 10.1007/s00232-014-9761-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 11/21/2014] [Indexed: 10/24/2022]
Abstract
Niemann-Pick type C disease (NPC) is a neurodegenerative genetic disorder caused by accumulation of lipids, especially cholesterol, in the perinuclear space. U18666A is a cholesterol transport-inhibiting agent, being used to mimic NPC, mainly in fibroblasts. The objective of this study was to observe the effect of the drug U18666A, which causes the accumulation of cholesterol in the cytoplasm of astrocytes from newborn rats, on some lysosomal hydrolase activities. Filipin staining and fluorescence microscopy, through CellM software, were used for visualization and quantification of cholesterol. The dose of U18666A that provided the greatest accumulation of cholesterol was that of 0.25 µg/mL in incubation for 48 h. Primary rat astrocytes incubated with the drug (NPC) showed a significantly higher amount of cholesterol than those without U18666A (controls). The measurement of activity of enzymes sphingomyelinase and beta-glucosidase in astrocytes of rats with NPC was significantly lower than that of control astrocytes, which is consistent with the disease in humans. The activity of the enzyme beta-galactosidase showed no significant difference between both groups. We concluded that U18666A appears to be an excellent intracellular cholesterol transport-inhibiting agent affecting some metabolic pathways in astrocytes of young rats, which mimics NPC in these animals. Just like the change in the activity of lysosomal enzymes has been demonstrated, other biochemical parameters of the cell can be tested with this animal model, thus contributing to a better understanding of the disease.
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Affiliation(s)
- Daniela Copetti Santos
- Lysosomal Storage Diseases Laboratory, Biochemistry Department, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil,
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Abstract
Niemann-Pick disease type C (NPC) is an atypical neurovisceral lysosomal storage disorder resulting from mutations in either the NPC1 or the NPC2 gene, currently conceived as a lipid trafficking disorder. Impaired egress of cholesterol from the late endosomal/lysosomal (LE/L) compartment is a key element of the pathogenesis. The resulting accumulation of unesterified cholesterol in the LE/L compartment can be visualized by fluorescence microscopy after staining with filipin. The "filipin test," performed on cultured fibroblasts, is the historical gold standard method to establish the diagnosis in patients. The authors provide methodological details of the protocol developed and used in their laboratory since 1988, in which two sources of low-density lipoproteins (LDL) (total serum and pure LDL) are used in parallel to facilitate the final interpretation. Methodological caveats and variability of patterns encountered in patients with proven Niemann-Pick C disease (typical "classic" or "intermediate," atypical "variant") are described. An overview of the past 5 years referrals (533 subjects tested, 57 NPC cases, but also 74 mildly/weakly positive tests not due to NPC) is discussed, leading to a proposed algorithm for interpretation of results in the filipin test. This tool takes into account the limits of the method. In up to 15% of all referrals, the filipin test was inconclusive in absence of molecular analysis. Patients diagnosed in the adult age preferentially showed an "intermediate" or "variant" pattern. Well conducted, the filipin test remains an efficient approach for diagnosing NPC, and it is a good functional test to study the pathogenicity of novel mutations.
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Sechi A, Dardis A, Zampieri S, Rabacchi C, Zanoni P, Calandra S, De Maglio G, Pizzolitto S, Maruotti V, Di Muzio A, Platt F, Bembi B. Effects of miglustat treatment in a patient affected by an atypical form of Tangier disease. Orphanet J Rare Dis 2014; 9:143. [PMID: 25227739 PMCID: PMC4172812 DOI: 10.1186/s13023-014-0143-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 08/27/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Tangier disease (TD) is a rare autosomal recessive disorder, resulting from mutations in the ATP binding cassette transporter (ABCA1) gene. The deficiency of ABCA1 protein impairs high density lipoprotein (HDL) synthesis and cholesterol esters trafficking. CASE REPORT A 58 year-old female, presenting with complex clinical signs (splenomegaly, dysarthria, dysphagia, ataxia, tongue enlargement, prurigo nodularis, legs lymphedema, pancytopenia and bone marrow foam cells), was misdiagnosed as Niemann-Pick C (NPC) and treated with miglustat (300 mg/day), normalizing neurological symptoms and improving skin lesions and legs lymphedema. Subsequently filipin-staining and molecular analysis for NPC genes were negative. Lipid profiling showed severe deficiency of HDL, 2 mg/dl (n.v. 45-65) and apoAI, 5.19 mg/dl (n.v. 110-170), suggesting TD as a probable diagnosis. Molecular analysis of ABCA1 gene showed the presence of a novel homozygous deletion (c.4464-486_4698 + 382 Del). Miglustat treatment was then interrupted with worsening of some neurological signs (memory defects, slowing of thought processes) and skin lesions. Treatment was restarted after 7 months with neurological normalization and improvement of skin involvement. CONCLUSIONS These results suggest miglustat as a possible therapeutic approach in this untreatable disease. The mechanisms by which miglustat ameliorates at least some clinical manifestations of TD needs to be further investigated.
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Kwiatkowska K, Marszałek–Sadowska E, Traczyk G, Koprowski P, Musielak M, Ługowska A, Kulma M, Grzelczyk A, Sobota A. Visualization of cholesterol deposits in lysosomes of Niemann-Pick type C fibroblasts using recombinant perfringolysin O. Orphanet J Rare Dis 2014; 9:64. [PMID: 24775609 PMCID: PMC4005833 DOI: 10.1186/1750-1172-9-64] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 04/16/2014] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Niemann-Pick disease type C (NPC) is caused by defects in cholesterol efflux from lysosomes due to mutations of genes coding for NPC1 and NPC2 proteins. As a result, massive accumulation of unesterified cholesterol in late endosomes/lysosomes is observed. At the level of the organism these cholesterol metabolism disorders are manifested by progressive neurodegeneration and hepatosplenomegaly. Until now filipin staining of cholesterol deposits in cells has been widely used for NPC diagnostics. In this report we present an alternative method for cholesterol visualization and estimation using a cholesterol-binding bacterial toxin, perfringolysin O. METHODS To detect cholesterol deposits, a recombinant probe, perfringolysin O fused with glutathione S-transferase (GST-PFO) was prepared. GST-PFO followed by labeled antibodies or streptavidin was applied for immunofluorescence and immunoelectron microscopy to analyze cholesterol distribution in cells derived from NPC patients. The identity of GST-PFO-positive structures was revealed by a quantitative analysis of their colocalization with several organelle markers. Cellular ELISA using GST-PFO was developed to estimate the level of unesterified cholesterol in NPC cells. RESULTS GST-PFO recognized cholesterol with high sensitivity and selectivity, as demonstrated by a protein/lipid overlay assay and surface plasmon resonance analysis. When applied to stain NPC cells, GST-PFO decorated abundant deposits of cholesterol in intracellular vesicles that colocalized with filipin-positive structures. These cholesterol deposits were resistant to 0.05%-0.2% Triton X-100 used for cells permeabilization in the staining procedure. GST-PFO-stained organelles were identified as late endosomes/lysosomes based on their colocalization with LAMP-1 and lysobisphosphatidic acid. On the other hand, GST-PFO did not colocalize with markers of the Golgi apparatus, endoplasmic reticulum, peroxisomes or with actin filaments. Only negligible GST-PFO staining was seen in fibroblasts of healthy individuals. When applied to cellular ELISA, GST-PFO followed by anti-GST-peroxidase allowed a semiquantitative analysis of cholesterol level in cells of NPC patients. Binding of GST-PFO to NPC cells was nearly abolished after extraction of cholesterol with methyl-β-cyclodextrin. CONCLUSIONS Our data indicate that a recombinant protein GST-PFO can be used to detect cholesterol accumulated in NPC cells by immunofluorescence and cellular ELISA. GST-PFO can be a convenient and reliable probe for revealing cholesterol deposits in cells and can be useful in diagnostics of NPC disease.
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Affiliation(s)
- Katarzyna Kwiatkowska
- Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Ewelina Marszałek–Sadowska
- Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Gabriela Traczyk
- Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Piotr Koprowski
- Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Małgorzata Musielak
- Department of Genetics, Institute of Psychiatry and Neurology, 9 Sobieskiego St., 02-957 Warsaw, Poland
| | - Agnieszka Ługowska
- Department of Genetics, Institute of Psychiatry and Neurology, 9 Sobieskiego St., 02-957 Warsaw, Poland
| | - Magdalena Kulma
- Institute of Biochemistry and Biophysics, 5a Pawinskiego St., 02-106 Warsaw, Poland
| | - Anna Grzelczyk
- Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
| | - Andrzej Sobota
- Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
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Niemann-Pick C disease gene mutations and age-related neurodegenerative disorders. PLoS One 2013; 8:e82879. [PMID: 24386122 PMCID: PMC3875432 DOI: 10.1371/journal.pone.0082879] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 10/28/2013] [Indexed: 02/07/2023] Open
Abstract
Niemann-Pick type C (NPC) disease is a rare autosomal-recessively inherited lysosomal storage disorder caused by mutations in NPC1 (95%) or NPC2. Given the highly variable phenotype, diagnosis is challenging and particularly late-onset forms with predominantly neuropsychiatric presentations are likely underdiagnosed. Pathophysiologically, genetic alterations compromising the endosomal/lysosomal system are linked with age-related neurodegenerative disorders. We sought to examine a possible association of rare sequence variants in NPC1 and NPC2 with Parkinson's disease (PD), frontotemporal lobar degeneration (FTLD) and progressive supranuclear palsy (PSP), and to genetically determine the proportion of potentially misdiagnosed NPC patients in these neurodegenerative conditions. By means of high-resolution melting, we screened the coding regions of NPC1 and NPC2 for rare genetic variation in a homogenous German sample of patients clinically diagnosed with PD (n = 563), FTLD (n = 133) and PSP (n = 94), and 846 population-based controls. The frequencies of rare sequence variants in NPC1/2 did not differ significantly between patients and controls. Disease-associated NPC1/2 mutations were found in six PD patients (1.1%) and seven control subjects (0.8%), but not in FTLD or PSP. All rare variation was detected in the heterozygous state and no compound heterozygotes were observed. Our data do not support the hypothesis that rare NPC1/2 variants confer susceptibility for PD, FTLD, or PSP in the German population. Misdiagnosed NPC patients were not present in our samples. However, further assessment of NPC disease genes in age-related neurodegeneration is warranted.
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Trilck M, Hübner R, Seibler P, Klein C, Rolfs A, Frech MJ. Niemann-Pick type C1 patient-specific induced pluripotent stem cells display disease specific hallmarks. Orphanet J Rare Dis 2013; 8:144. [PMID: 24044630 PMCID: PMC3848807 DOI: 10.1186/1750-1172-8-144] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 09/15/2013] [Indexed: 12/31/2022] Open
Abstract
Background Niemann-Pick type C1 disease (NPC1) is a rare progressive neurodegenerative disorder caused by mutations in the NPC1 gene. In this lysosomal storage disorder the intracellular transport and sequestration of several lipids like cholesterol is severely impaired, resulting in an accumulation of lipids in late endosomes and lysosomes. The neurological manifestation of the disease is caused by dysfunction and cell death in the central nervous system. Several animal models were used to analyze the impaired pathways. However, the underlying pathogenic mechanisms are still not completely understood and the genetic variability in humans cannot be reflected in these models. Therefore, a human model using patient-specific induced pluripotent stem cells provides a promising approach. Methods We reprogrammed human fibroblasts from a NPC1 patient and a healthy control by retroviral transduction with Oct4, Klf4, Sox2 and c-Myc. The obtained human induced pluripotent stem cells (hiPSCs) were characterized by immunocytochemical analyses. Neural progenitor cells were generated and patch clamp recordings were performed for a functional analysis of derived neuronal cells. Filipin stainings and the Amplex Red assay were used to demonstrate and quantify cholesterol accumulation. Results The hiPSCs expressed different stem cell markers, e.g. Nanog, Tra-1-81 and SSEA4. Using the embryoid body assay, the cells were differentiated in cells of all three germ layers and induced teratoma in immunodeficient mice, demonstrating their pluripotency. In addition, neural progenitor cells were derived and differentiated into functional neuronal cells. Patch clamp recordings revealed voltage dependent channels, spontaneous action potentials and postsynaptic currents. The accumulation of cholesterol in different tissues is the main hallmark of NPC1. In this study we found an accumulation of cholesterol in fibroblasts of a NPC1 patient, derived hiPSCs, and neural progenitor cells, but not in cells derived from fibroblasts of a healthy individual. These findings were quantified by the Amplex Red assay, demonstrating a significantly elevated cholesterol level in cells derived from fibroblasts of a NPC1 patient. Conclusions We generated a neuronal model based on induced pluripotent stem cells derived from patient fibroblasts, providing a human in vitro model to study the pathogenic mechanisms of NPC1 disease.
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Affiliation(s)
- Michaela Trilck
- Albrecht-Kossel-Institute for Neuroregeneration (AKos), University of Rostock, Gehlsheimer Strasse 20, D-18147 Rostock, Germany.
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Stampfer M, Theiss S, Amraoui Y, Jiang X, Keller S, Ory DS, Mengel E, Fischer C, Runz H. Niemann-Pick disease type C clinical database: cognitive and coordination deficits are early disease indicators. Orphanet J Rare Dis 2013; 8:35. [PMID: 23433426 PMCID: PMC3649939 DOI: 10.1186/1750-1172-8-35] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Accepted: 02/18/2013] [Indexed: 11/24/2022] Open
Abstract
Background The neurodegenerative lysosomal storage disorder Niemann-Pick disease type C (NP-C) is characterized by a broad clinical variability involving neurological, psychiatric and systemic signs. Diverse patterns of disease manifestation and progression considerably delay its diagnosis. Here we introduce the NP-C clinical database (NPC-cdb) to systematically obtain, store and analyze diagnostic and clinical findings in patients with NP-C. We apply NPC-cdb to study NP-C temporal expression in a large German-Swiss patient cohort. Methods Current and past medical history was systematically acquired from 42 patients using tailored questionnaires. Manifestation of 72 distinct neuropsychiatric signs was modeled over the course of disease. The sequence of disease progression was re-constructed by a novel clinical outcome scale (NPC-cdb score). Results The efficiency of current clinical diagnostic standards negatively correlates with duration of disease (p<3.9x10-4), suggesting insufficient sensitivity in patients early in the disease process. Neurological signs considered as typical for NP-C were frequent (e.g., cognitive impairment 86%, ataxia 79%, vertical supranuclear gaze palsy 76%) and their presence co-occurred with accelerated diagnosis. However, less specific neuropsychiatric signs were reported to arise considerably more early in the disease process (e.g., clumsiness -4.9±1.1 y before diagnosis). Most patients showed a steady disease progression that correlated with age at neurological onset. However, a distinct subcohort (n=6) with initially steadily progressing disease later showed a 2.9-fold accelerated progression that was associated with the onset of seizures (p<7x10-4), suggesting seizures as predictive for a poor prognosis. Conclusions Considering early, but less specific neuropsychiatric signs may accelerate the path to diagnosing NP-C in a patient.
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Affiliation(s)
- Miriam Stampfer
- Institute of Human Genetics, University of Heidelberg, Heidelberg 69120, Germany
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Chien YH, Peng SF, Yang CC, Lee NC, Tsai LK, Huang AC, Su SC, Tseng CC, Hwu WL. Long-term efficacy of miglustat in paediatric patients with Niemann-Pick disease type C. J Inherit Metab Dis 2013; 36:129-37. [PMID: 22476655 DOI: 10.1007/s10545-012-9479-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Revised: 03/07/2012] [Accepted: 03/12/2012] [Indexed: 10/28/2022]
Abstract
Niemann-Pick disease type C (NP-C) is a rare inherited neurovisceral disease characterized by progressive neurological manifestations. Oral miglustat was first approved for the treatment of children and adults with NP-C in Europe in 2009. There are still relatively few published data on the long-term efficacy and safety of miglustat in patients with NP-C in clinical practice. We report the effects of up to 6 years of treatment with miglustat 100 mg t.i.d. in five children. Overall, 3/5 patients displayed progressive dysphagia before starting miglustat, and 4/5 showed marked cognitive and/or motor impairment. The mean age at treatment start was 11.6 years, and the median (range) duration of therapy so far is 4 (4.1 to 6.1) years. No treatment dose alterations were required, but therapy was interrupted for 1-3 months at least once in all patients due to supply issues. Swallowing function was stabilised during miglustat therapy, with no significant increase in Han dysphagia scale or aspiration-penetration index scores among four evaluable patients (p > 0.05). Scores on the mini-mental state examination indicated an improvement in cognitive function during the first 3-6 months of miglustat therapy, followed by stabilisation up to 5 years. Ambulatory function remained stable for at least the first 2 years of treatment in most patients, but there was a trend towards deterioration thereafter, possibly related to treatment interruptions. The safety/tolerability profile of miglustat was similar to previous clinical studies, although reports of gastrointestinal disturbances were rare. Overall, miglustat appeared to stabilise key parameters of neurological disease progression.
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Affiliation(s)
- Y H Chien
- Department of Pediatrics, National Taiwan University Hospital, Taipei, Taiwan
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Iatan I, Palmyre A, Alrasheed S, Ruel I, Genest J. Genetics of cholesterol efflux. Curr Atheroscler Rep 2012; 14:235-46. [PMID: 22528521 DOI: 10.1007/s11883-012-0247-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Plasma levels of high-density lipoprotein cholesterol (HDL-C) show an inverse association with coronary heart disease (CHD). As a biological trait, HDL-C is strongly genetically determined, with a heritability index ranging from 40 % to 60 %. HDL represents an appealing therapeutic target due to its beneficial pleiotropic effects in preventing CHD. This review focuses on the genetic basis of cellular cholesterol efflux, the rate-limiting step in HDL biogenesis. There are several monogenic disorders (e.g., Tangier disease, caused by mutations within ABCA1) affecting HDL biogenesis. Importantly, many disorders of cellular cholesterol homeostasis cause a reduced HDL-C. We integrate information from family studies and linkage analyses with that derived from genome-wide association studies (GWAS) and review the recent identification of micro-RNAs (miRNA) involved in cellular cholesterol metabolism. The identification of genomic pathways related to HDL may help pave the way for novel therapeutic approaches to promote cellular cholesterol efflux as a therapeutic modality to prevent atherosclerosis.
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Affiliation(s)
- Iulia Iatan
- Cardiovascular Research Laboratories, Division of Cardiology, Department of Biochemistry, Faculty of Medicine, McGill University, Montreal, QC, Canada
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Patterson MC, Hendriksz CJ, Walterfang M, Sedel F, Vanier MT, Wijburg F. Recommendations for the diagnosis and management of Niemann-Pick disease type C: an update. Mol Genet Metab 2012; 106:330-44. [PMID: 22572546 DOI: 10.1016/j.ymgme.2012.03.012] [Citation(s) in RCA: 312] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2012] [Revised: 03/16/2012] [Accepted: 03/16/2012] [Indexed: 12/18/2022]
Abstract
Niemann-Pick disease type C (NP-C) is a rare inherited neurovisceral disease caused by mutations in either the NPC1 (in 95% of cases) or the NPC2 gene (in around 5% of cases), which lead to impaired intracellular lipid trafficking and accumulation of cholesterol and glycosphingolipids in the brain and other tissues. Characteristic neurological manifestations of NP-C include saccadic eye movement (SEM) abnormalities or vertical supranuclear gaze palsy (VSGP), cerebellar signs (ataxia, dystonia/dysmetria, dysarthria and dysphagia) and gelastic cataplexy. Epileptic seizures are also common in affected patients. Typically, neurological disease onset occurs during childhood, although an increasing number of cases are being detected and diagnosed during adulthood based on late-onset neurological signs and psychiatric manifestations. Categorization of patients according to age at onset of neurological manifestations (i.e. early-infantile, late-infantile, juvenile and adolescent/adult-onset) can be useful for the evaluation of disease course and treatment responses. The first international guidelines for the clinical management of NP-C in children and adults were published in 2009. Since that time a significant amount of data regarding the epidemiology, detection/diagnosis, and treatment of NP-C has been published. Here, we report points of consensus among experts in the diagnosis and treatment of NP-C based on a follow-up meeting in Paris, France in September 2011. This article serves as an update to the original guidelines providing, among other things, further information on detection/diagnostic methods, potential new methods of monitoring disease progression, and therapy. Treatment goals and the application of disease-specific therapy with miglustat are also re-evaluated.
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Boadu E, Nelson RC, Francis GA. ABCA1-dependent mobilization of lysosomal cholesterol requires functional Niemann-Pick C2 but not Niemann-Pick C1 protein. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:396-404. [PMID: 22179027 DOI: 10.1016/j.bbalip.2011.11.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 10/28/2011] [Accepted: 11/28/2011] [Indexed: 10/14/2022]
Abstract
Niemann-Pick disease type C (NPC) is caused by mutations leading to loss of function of NPC1 or NPC2 proteins, resulting in accumulation of unesterified cholesterol in late endosomes and lysosomes. We previously reported that expression of the ATP-binding cassette transporter A1 (ABCA1) is impaired in human NPC1(-/-) fibroblasts, resulting in reduced HDL particle formation and providing a mechanism for the reduced plasma HDL cholesterol seen in the majority of NPC1 patients. We also found that treatment of NPC1(-/-) fibroblasts with an agonist of liver X-receptor corrects ABCA1 expression and HDL formation and reduces lysosomal cholesterol accumulation. We have confirmed that ABCA1 expression is also reduced in NPC2(-/-) cells, and found that α-HDL particle formation is impaired in these cells. To determine whether selective up-regulation of ABCA1 can correct lysosomal cholesterol accumulation in NPC disease cells and HDL particle formation, we produced and infected NPC1(-/-) and NPC2(-/-) fibroblasts with an adenovirus expressing full-length ABCA1 and enhanced green fluorescent protein (AdABCA1-EGFP). ABCA1-EGFP expression in NPC1(-/-) fibroblasts resulted in normalization of cholesterol efflux to apolipoprotein A-I (apoA-I) and α-HDL particle formation, plus a marked reduction in filipin staining of unesterified cholesterol in late endosomes/lysosomes. In contrast, AdABCA1-EGFP treatment of NPC2(-/-) fibroblasts to normalize ABCA1 expression had no effect on cholesterol efflux to apoA-I or accumulation of excess cholesterol in lysosomes, and only partially corrected α-HDL formation by these cells. These results suggest that correction of ABCA1 expression can bypass the mutation of NPC1 but not NPC2 to mobilize excess cholesterol from late endosomes and lysosomes in NPC disease cells. Expression of ABCA1-EGFP in NPC1(-/-) cells increased cholesterol available for esterification and reduced levels of HMG-CoA reductase protein, effects that were abrogated by co-incubation with apoA-I. A model can be generated in which ABCA1 is able to mobilize cholesterol, to join the intracellular regulatory pool or to be effluxed for HDL particle formation, either directly or indirectly from the lysosomal membrane, but not from the lysosomal lumen. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).
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Affiliation(s)
- Emmanuel Boadu
- Department of Medicine and UBC James Hogg Research Centre, Providence Heart and Lung Institute, University of British Columbia, Vancouver, Canada
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Jiang X, Sidhu R, Porter FD, Yanjanin NM, Speak AO, te Vruchte DT, Platt FM, Fujiwara H, Scherrer DE, Zhang J, Dietzen DJ, Schaffer JE, Ory DS. A sensitive and specific LC-MS/MS method for rapid diagnosis of Niemann-Pick C1 disease from human plasma. J Lipid Res 2011; 52:1435-45. [PMID: 21518695 DOI: 10.1194/jlr.d015735] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Niemann-Pick type C1 (NPC1) disease is a rare, progressively fatal neurodegenerative disease for which there are no FDA-approved therapies. A major barrier to developing new therapies for this disorder has been the lack of a sensitive and noninvasive diagnostic test. Recently, we demonstrated that two cholesterol oxidation products, specifically cholestane-3β,5α,6β-triol (3β,5α,6β-triol) and 7-ketocholesterol (7-KC), were markedly increased in the plasma of human NPC1 subjects, suggesting a role for these oxysterols in diagnosis of NPC1 disease and evaluation of therapeutics in clinical trials. In the present study, we describe the development of a sensitive and specific LC-MS/MS method for quantifying 3β,5α,6β-triol and 7-KC human plasma after derivatization with N,N-dimethylglycine. We show that dimethylglycine derivatization successfully enhanced the ionization and fragmentation of 3β,5α,6β-triol and 7-KC for mass spectrometric detection of the oxysterol species in human plasma. The oxysterol dimethylglycinates were resolved with high sensitivity and selectivity, and enabled accurate quantification of 3β,5α,6β-triol and 7-KC concentrations in human plasma. The LC-MS/MS assay was able to discriminate with high sensitivity and specificity between control and NPC1 subjects, and offers for the first time a noninvasive, rapid, and highly sensitive method for diagnosis of NPC1 disease.
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Affiliation(s)
- Xuntian Jiang
- Diabetic Cardiovascular Disease Center, Washington University School of Medicine, St. Louis, MO, USA
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