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Schnitker F, Liu Y, Keitsch S, Soddemann M, Verhasselt HL, Kehrmann J, Grassmé H, Kamler M, Gulbins E, Wu Y. Reduced Sphingosine in Cystic Fibrosis Increases Susceptibility to Mycobacterium abscessus Infections. Int J Mol Sci 2023; 24:14004. [PMID: 37762308 PMCID: PMC10530875 DOI: 10.3390/ijms241814004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 09/06/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023] Open
Abstract
Cystic fibrosis (CF) is an autosomal recessive disorder caused by the deficiency of the cystic fibrosis transmembrane conductance regulator (CFTR) and often leads to pulmonary infections caused by various pathogens, including Staphylococcus aureus, Pseudomonas aeruginosa, and nontuberculous mycobacteria, particularly Mycobacterium abscessus. Unfortunately, M. abscessus infections are increasing in prevalence and are associated with the rapid deterioration of CF patients. The treatment options for M. abscessus infections are limited, requiring the urgent need to comprehend infectious pathogenesis and develop new therapeutic interventions targeting affected CF patients. Here, we show that the deficiency of CFTR reduces sphingosine levels in bronchial and alveolar epithelial cells and macrophages from CF mice and humans. Decreased sphingosine contributes to the susceptibility of CF tissues to M. abscessus infection, resulting in a higher incidence of infections in CF mice. Notably, treatment of M. abscessus with sphingosine demonstrated potent bactericidal activity against the pathogen. Most importantly, restoration of sphingosine levels in CF cells, whether human or mouse, and in the lungs of CF mice, provided protection against M. abscessus infections. Our findings demonstrate that pulmonary sphingosine levels are important in controlling M. abscessus infection. These results offer a promising therapeutic avenue for CF patients with pulmonary M. abscessus infections.
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Affiliation(s)
- Fabian Schnitker
- Department of Molecular Biology, Institute of Molecular Biology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (F.S.); (Y.L.); (S.K.); (M.S.); (H.G.); (E.G.)
| | - Yongjie Liu
- Department of Molecular Biology, Institute of Molecular Biology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (F.S.); (Y.L.); (S.K.); (M.S.); (H.G.); (E.G.)
- West German Heart and Vascular Center, Thoracic Transplantation, Department of Thoracic and Cardiovascular Surgery, University Hospital Essen, University Duisburg-Essen, 45122 Essen, Germany;
| | - Simone Keitsch
- Department of Molecular Biology, Institute of Molecular Biology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (F.S.); (Y.L.); (S.K.); (M.S.); (H.G.); (E.G.)
| | - Matthias Soddemann
- Department of Molecular Biology, Institute of Molecular Biology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (F.S.); (Y.L.); (S.K.); (M.S.); (H.G.); (E.G.)
| | - Hedda Luise Verhasselt
- Institute of Medical Microbiology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (H.L.V.); (J.K.)
| | - Jan Kehrmann
- Institute of Medical Microbiology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (H.L.V.); (J.K.)
| | - Heike Grassmé
- Department of Molecular Biology, Institute of Molecular Biology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (F.S.); (Y.L.); (S.K.); (M.S.); (H.G.); (E.G.)
| | - Markus Kamler
- West German Heart and Vascular Center, Thoracic Transplantation, Department of Thoracic and Cardiovascular Surgery, University Hospital Essen, University Duisburg-Essen, 45122 Essen, Germany;
| | - Erich Gulbins
- Department of Molecular Biology, Institute of Molecular Biology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (F.S.); (Y.L.); (S.K.); (M.S.); (H.G.); (E.G.)
- Department of Surgery, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Yuqing Wu
- Department of Molecular Biology, Institute of Molecular Biology, University Hospital Essen, University of Duisburg-Essen, 45122 Essen, Germany; (F.S.); (Y.L.); (S.K.); (M.S.); (H.G.); (E.G.)
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2
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Abu-Arish A, Pandžić E, Luo Y, Sato Y, Turner MJ, Wiseman PW, Hanrahan JW. Lipid-driven CFTR clustering is impaired in CF and restored by corrector drugs. J Cell Sci 2022; 135:274066. [PMID: 35060604 PMCID: PMC8976878 DOI: 10.1242/jcs.259002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 01/08/2022] [Indexed: 11/20/2022] Open
Abstract
Membrane proteins often cluster in nanoscale membrane domains (lipid rafts) that coalesce into ceramide-rich platforms during cell stress, however the clustering mechanisms remain uncertain. The cystic fibrosis transmembrane conductance regulator (CFTR), which is mutated in cystic fibrosis (CF), forms clusters that are cholesterol-dependent and become incorporated into long-lived platforms during hormonal stimulation. We report here that clustering does not involve known tethering interactions of CFTR with PDZ domain proteins, filamin A or the actin cytoskeleton. It also does not require CFTR palmitoylation but is critically dependent on membrane lipid order and is induced by detergents that increase the phase separation of membrane lipids. Clustering and integration of CFTR into ceramide-rich platforms are abolished by the disease mutations F508del and S13F and rescued by the CFTR modulators elexacaftor+tezacaftor. These results indicate CF therapeutics that correct mutant protein folding restore both trafficking and normal lipid interactions in the plasma membrane.
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Affiliation(s)
- Asmahan Abu-Arish
- Department of Physiology, McGill University, Montréal QC H3G 1Y6, Canada
- Cystic Fibrosis Translational Research centre, McGill University, Canada
| | - Elvis Pandžić
- UNSW Australia, Biomedical Imaging Facility, Mark Wainwright Analytical Center, Sydney, Australia
| | - Yishan Luo
- Department of Physiology, McGill University, Montréal QC H3G 1Y6, Canada
- Cystic Fibrosis Translational Research centre, McGill University, Canada
| | - Yukiko Sato
- Department of Physiology, McGill University, Montréal QC H3G 1Y6, Canada
- Cystic Fibrosis Translational Research centre, McGill University, Canada
| | - Mark J. Turner
- Department of Physiology, McGill University, Montréal QC H3G 1Y6, Canada
- Cystic Fibrosis Translational Research centre, McGill University, Canada
| | - Paul W. Wiseman
- Department of Chemistry and Department of Physics, McGill University, Montréal, QC, Canada
| | - John W. Hanrahan
- Department of Physiology, McGill University, Montréal QC H3G 1Y6, Canada
- Cystic Fibrosis Translational Research centre, McGill University, Canada
- Research Institute of the McGill University Health Centre, Canada
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Cui G, Cottrill KA, Strickland KM, Mashburn SA, Koval M, McCarty NA. Alteration of Membrane Cholesterol Content Plays a Key Role in Regulation of Cystic Fibrosis Transmembrane Conductance Regulator Channel Activity. Front Physiol 2021; 12:652513. [PMID: 34163370 PMCID: PMC8215275 DOI: 10.3389/fphys.2021.652513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 04/23/2021] [Indexed: 11/30/2022] Open
Abstract
Altered cholesterol homeostasis in cystic fibrosis patients has been reported, although controversy remains. As a major membrane lipid component, cholesterol modulates the function of multiple ion channels by complicated mechanisms. However, whether cholesterol directly modulates cystic fibrosis transmembrane conductance regulator (CFTR) channel function remains unknown. To answer this question, we determined the effects of changing plasma membrane cholesterol levels on CFTR channel function utilizing polarized fischer rat thyroid (FRT) cells and primary human bronchial epithelial (HBE) cells. Treatment with methyl-β-cyclodextrin (MβCD) significantly reduced total cholesterol content in FRT cells, which significantly decreased forskolin (FSK)-mediated activation of both wildtype (WT-) and P67L-CFTR. This effect was also seen in HBE cells expressing WT-CFTR. Cholesterol modification by cholesterol oxidase and cholesterol esterase also distinctly affected activation of CFTR by FSK. In addition, alteration of cholesterol increased the potency of VX-770, a clinically used potentiator of CFTR, when both WT- and P67L-CFTR channels were activated at low FSK concentrations; this likely reflects the apparent shift in the sensitivity of WT-CFTR to FSK after alteration of membrane cholesterol. These results demonstrate that changes in the plasma membrane cholesterol level significantly modulate CFTR channel function and consequently may affect sensitivity to clinical therapeutics in CF patients.
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Affiliation(s)
- Guiying Cui
- Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, GA, United States
| | - Kirsten A Cottrill
- Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, GA, United States
| | - Kerry M Strickland
- Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, GA, United States
| | - Sarah A Mashburn
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA, United States
| | - Michael Koval
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA, United States
| | - Nael A McCarty
- Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory + Children's Center for Cystic Fibrosis and Airways Disease Research, Emory University School of Medicine and Children's Healthcare of Atlanta, Atlanta, GA, United States
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Drzymała-Czyż S, Krzyżanowska-Jankowska P, Dziedzic K, Lisowska A, Kurek S, Goździk-Spychalska J, Kononets V, Woźniak D, Mądry E, Walkowiak J. Severe Genotype, Pancreatic Insufficiency and Low Dose of Pancreatic Enzymes Associate with Abnormal Serum Sterol Profile in Cystic Fibrosis. Biomolecules 2021; 11:313. [PMID: 33669566 PMCID: PMC7922133 DOI: 10.3390/biom11020313] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/13/2021] [Accepted: 02/16/2021] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Several factors could lead to lipid disturbances observed in cystic fibrosis (CF). This study aimed to assess sterol homeostasis in CF and define potential exogenous and endogenous determinants of lipid dysregulation. METHODS The study involved 55 CF patients and 45 healthy subjects (HS). Sterol concentrations (μg/dL) were measured by gas chromatography/mass spectrometry. CF was characterised by lung function, pancreatic status, liver disease and diabetes coexistence, Pseudomonas aeruginosa colonisation and BMI. CFTR genotypes were classified as severe or other. RESULTS Campesterol and β-sitosterol concentrations were lower (p = 0.0028 and p < 0.0001, respectively) and lathosterol levels (reflecting endogenous cholesterol biosynthesis) were higher (p = 0.0016) in CF patients than in HS. Campesterol and β-sitosterol concentrations were lower in patients with a severe CFTR genotype, pancreatic insufficiency and lower pancreatic enzyme dose (lipase units/gram of fat). In multiple regression analyses, β-sitosterol and campesterol concentrations were predicted by genotype and pancreatic insufficiency, whereas cholesterol and its fractions were predicted by phytosterol concentrations, age, dose of pancreatic enzymes, nutritional status and genotype. CONCLUSIONS Independent determinants of lipid status suggest that malabsorption and pancreatic enzyme supplementation play a significant role in sterol abnormalities. The measurement of campesterol and β-sitosterol concentrations in CF patients may serve for the assessment of the effectiveness of pancreatic enzyme replacement therapy and/or compliance, but further research is required.
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Affiliation(s)
- Sławomira Drzymała-Czyż
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, 60-572 Poznań, Poland; (P.K.-J.); (K.D.); (A.L.); (S.K.); (J.W.)
- Department of Bromatology, Poznan University of Medical Sciences, 60-354 Poznań, Poland;
| | - Patrycja Krzyżanowska-Jankowska
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, 60-572 Poznań, Poland; (P.K.-J.); (K.D.); (A.L.); (S.K.); (J.W.)
| | - Krzysztof Dziedzic
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, 60-572 Poznań, Poland; (P.K.-J.); (K.D.); (A.L.); (S.K.); (J.W.)
- Department of Food Science and Nutrition, Institute of Food Technology of Plant Origin, Poznań University of Life Sciences, 60-637 Poznań, Poland
| | - Aleksandra Lisowska
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, 60-572 Poznań, Poland; (P.K.-J.); (K.D.); (A.L.); (S.K.); (J.W.)
| | - Szymon Kurek
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, 60-572 Poznań, Poland; (P.K.-J.); (K.D.); (A.L.); (S.K.); (J.W.)
| | - Joanna Goździk-Spychalska
- Department of Pulmonology, Allergology and Respiratory Oncology, Poznan University of Medical Sciences, 60-569 Poznań, Poland;
| | - Victoria Kononets
- Department of Natural Sciences Disciplines, West Kazakhstan Marat Ospanov Medical University, Aktobe 030012, Kazakhstan;
| | - Dagmara Woźniak
- Department of Bromatology, Poznan University of Medical Sciences, 60-354 Poznań, Poland;
| | - Edyta Mądry
- Department of Physiology, Poznan University of Medical Sciences, 61-781 Poznań, Poland;
| | - Jarosław Walkowiak
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, 60-572 Poznań, Poland; (P.K.-J.); (K.D.); (A.L.); (S.K.); (J.W.)
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Amato F, Castaldo A, Castaldo G, Cernera G, Corso G, Ferrari E, Gelzo M, Monzani R, Villella VR, Raia V. Impaired cholesterol metabolism in the mouse model of cystic fibrosis. A preliminary study. PLoS One 2021; 16:e0245302. [PMID: 33412572 PMCID: PMC7790534 DOI: 10.1371/journal.pone.0245302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/24/2020] [Indexed: 11/19/2022] Open
Abstract
This study aims to investigate cholesterol metabolism in a mouse model with cystic fibrosis (CF) by the comparison of affected homozygous versus wild type (WT) mice. In particular, we evaluated the effects of a diet enriched with cholesterol in both mice groups in comparison with the normal diet. To this purpose, beyond serum and liver cholesterol, we analyzed serum phytosterols as indirect markers of intestinal absorption of cholesterol, liver lathosterol as indirect marker of de novo cholesterol synthesis, liver cholestanol (a catabolite of bile salts synthesis) and the liver mRNA levels of LDL receptor (LDLR), 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoAR), acyl CoA:cholesterol acyl transferase 2 (ACAT2), cytochrome P450 7A1 (CYP7A1) and tumor necrosis factor alpha (TNFα). CF mice showed lower intestinal absorption and higher liver synthesis of cholesterol than WT mice. In WT mice, the cholesterol supplementation inhibits the synthesis of liver cholesterol and enhances its catabolism, while in CF mice we did not observe a reduction of LDLR and HMG-CoAR expression (probably due to an altered feed-back), causing an increase of intracellular cholesterol. In addition, we observed a further increase (5-fold) in TNFα mRNA levels. This preliminary study suggests that in CF mice there is a vicious circle in which the altered synthesis/secretion of bile salts may reduce the digestion/absorption of cholesterol. As a result, the liver increases the biosynthesis of cholesterol that accumulates in the cells, triggering inflammation and further compromising the metabolism of bile salts.
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Affiliation(s)
- Felice Amato
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, University of Naples Federico II, Naples, Italy
- CEINGE-Biotecnologie Avanzate, Scarl, Naples, Italy
| | - Alice Castaldo
- Dipartimento di Scienze Mediche Traslazionali, University of Naples Federico II, Naples, Italy
| | - Giuseppe Castaldo
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, University of Naples Federico II, Naples, Italy
- CEINGE-Biotecnologie Avanzate, Scarl, Naples, Italy
| | - Gustavo Cernera
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, University of Naples Federico II, Naples, Italy
- CEINGE-Biotecnologie Avanzate, Scarl, Naples, Italy
| | - Gaetano Corso
- Dipartimento di Medicina Clinica e Sperimentale, University of Foggia, Foggia, Italy
- * E-mail:
| | - Eleonora Ferrari
- European Institute for Research in Cystic Fibrosis, San Raffaele Scientific Institute, Milan, Italy
- Dipartimento di Scienze della Salute, University of Eastern Piedmont, Novara, Italy
| | - Monica Gelzo
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, University of Naples Federico II, Naples, Italy
- CEINGE-Biotecnologie Avanzate, Scarl, Naples, Italy
| | - Romina Monzani
- European Institute for Research in Cystic Fibrosis, San Raffaele Scientific Institute, Milan, Italy
- Dipartimento di Scienze della Salute, University of Eastern Piedmont, Novara, Italy
| | - Valeria Rachela Villella
- European Institute for Research in Cystic Fibrosis, San Raffaele Scientific Institute, Milan, Italy
| | - Valeria Raia
- Dipartimento di Scienze Mediche Traslazionali, University of Naples Federico II, Naples, Italy
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Abstract
Cystic Fibrosis (CF) is the most common life-shortening genetic disease among Caucasians, resulting from mutations in the gene encoding the Cystic Fibrosis Transmembrane conductance Regulator (CFTR). While work to understand this protein has resulted in new treatment strategies, it is important to emphasize that CFTR exists within a complex lipid bilayer — a concept largely overlooked when performing structural and functional studies. In this review we discuss cellular lipid imbalances in CF, mechanisms by which lipids affect membrane protein activity, and the specific impact of detergents and lipids on CFTR function. In this review, Cottrill et al. discuss how the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) interacts with the membrane into which it is inserted. They summarize recent insight into the ways lipids are imbalanced in CF epithelia and how the lipid environment affects CFTR.
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Rosenjack J, Hodges CA, Darrah RJ, Kelley TJ. HDAC6 depletion improves cystic fibrosis mouse airway responses to bacterial challenge. Sci Rep 2019; 9:10282. [PMID: 31311988 PMCID: PMC6635416 DOI: 10.1038/s41598-019-46555-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 06/29/2019] [Indexed: 02/07/2023] Open
Abstract
The hypothesis of this study was that Hdac6 depletion would restore cystic fibrosis (CF) responses to bacterial challenge to more wild type profiles using a CF mouse model. CF mice harboring the F508del Cftr mutation respond to bacterial challenge with 25,000 CFU Pseudomonas aeruginosa embedded into agarose beads to slow clearance. CF mice respond significantly more aggressively to this challenge compared to WT mice with respect to bacterial clearance, weight loss, neutrophil recruitment, and MIP-2 production. Depletion of Hdac6 expression in the CF mice (CF/Hdac6) significantly improves these responses to more WT levels. Weight loss in response to infection is most severe in CF mice and significantly attenuated in CF/Hdac6 mice. Bacterial levels are reduced at a faster rate in CF/Hdac6 mice compared to CF mice where infection persists. Percent neutrophils in lung lavage fluid post-infection are significantly higher in CF mice, but returned to WT levels with CF/Hdac6 mice. Similarly, CF Mip-2 levels are restored to WT levels in the absence of Hdac6 expression. These data demonstrate that Hdac6 depletion restores CF responses to bacterial challenge to WT-like profiles and offer a potential therapeutic avenue for addressing inflammation and infection in CF airways independently of Cftr correction.
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Affiliation(s)
- Julie Rosenjack
- Departments of Pediatrics, Case Western Reserve University Cleveland, Ohio, USA
| | - Craig A Hodges
- Departments of Pediatrics, Case Western Reserve University Cleveland, Ohio, USA
| | - Rebecca J Darrah
- Departments of Pediatrics, Case Western Reserve University Cleveland, Ohio, USA
| | - Thomas J Kelley
- Departments of Pediatrics, Case Western Reserve University Cleveland, Ohio, USA.
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8
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Lu B, Li L, Schneider M, Hodges CA, Cotton CU, Burgess JD, Kelley TJ. Electrochemical measurement of membrane cholesterol correlates with CFTR function and is HDAC6-dependent. J Cyst Fibros 2018; 18:175-181. [PMID: 29941319 DOI: 10.1016/j.jcf.2018.06.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 06/06/2018] [Accepted: 06/07/2018] [Indexed: 12/18/2022]
Abstract
BACKGROUND Previous studies have demonstrated that CF epithelial cells exhibit increased cholesterol content at the plasma membrane compared to wild type controls as measured by electrochemical methods. Microtubule dysregulation that impacts intracellular transport has also been identified in CF cells and is reversible with histone deacetylase 6 (HDAC6) inhibition, a regulator of tubulin acetylation. The hypothesis of this study is that increased membrane cholesterol content in CF cells is dependent on HDAC6 regulation. METHODS Electrochemical measurement of membrane cholesterol in mouse trachea and in primary human CF bronchial epithelial cells is used to monitor CFTR correction and manipulation of cholesterol processing by HDAC6 inhibition. RESULTS Data demonstrate that induction of Cftr expression in an inducible CF mouse model restores tubulin acetylation levels and normalizes membrane cholesterol content. To test the relationship between tubulin acetylation, membrane cholesterol levels were measured in a CF mouse model depleted of Hdac6 expression (CF/HDA). CF/HDA mouse trachea have WT membrane cholesterol levels while CF mice have approximately two-fold increase in membrane cholesterol compared to WT consistent with previous studies. Pharmacological inhibition of HDAC6 in primary human CF bronchial epithelial cells also reduces membrane cholesterol levels. CONCLUSIONS This study demonstrates that elevated membrane cholesterol in CF epithelium is regulated by HDAC6 function and that the electrochemical measure of membrane cholesterol correlates with both genetic and pharmacological CFTR correction.
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Affiliation(s)
- Binyu Lu
- Department of Chemistry, Case Western Reserve University, United States
| | - Li Li
- Department of Chemistry, Case Western Reserve University, United States
| | - Molly Schneider
- Department of Pediatrics, Case Western Reserve University, United States
| | - Craig A Hodges
- Department of Pediatrics, Case Western Reserve University, United States
| | - Calvin U Cotton
- Department of Pediatrics, Case Western Reserve University, United States
| | - James D Burgess
- Department of Medical, Laboratory, Imaging and Radiologic Sciences, Augusta University, United States
| | - Thomas J Kelley
- Department of Chemistry, Case Western Reserve University, United States; Department of Pediatrics, Case Western Reserve University, United States.
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9
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Li L, Lu B, Jiang D, Shin M, Kelley T, Burgess JD. Cell Plasma Membrane Cholesterol as a Diagnostic. CURRENT OPINION IN ELECTROCHEMISTRY 2017; 2:82-87. [PMID: 28758153 PMCID: PMC5526343 DOI: 10.1016/j.coelec.2017.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Cholesterol is a tightly regulated major structural component of the cell plasma membrane (PM) where it forms stoichiometric complexes with phospholipids and sphingolipids. The amount of cholesterol in the PM exhibits a regulatory role in basal activity of several biomolecular processes by direct binding to proteins and by indirect local environmental effects within the PM that are also coupled to overall cellular cholesterol homeostasis. The term "active cholesterol" refers to PM cholesterol not complexed to lipids, a cholesterol state that arises above a threshold mole fraction of cholesterol in the PM. Active cholesterol level in the PM provides a control mechanism for cellular cholesterol homeostasis through its recognition by membrane bound proteins that activate genes of cholesterol synthesis enzymes. Uptake of LDL, production and release of HDL as well as reversible storage of cholesterol in the cytosol by covalent modification are also regulated and dependent on PM cholesterol (thermodynamic) activity: active cholesterol. A number of human disease states have been found to have associated alterations in PM cholesterol and thus a method for its determination is described.
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Affiliation(s)
- Li Li
- Department of Chemistry, Case Western Reserve University, Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106, USA
| | - Binyu Lu
- Department of Chemistry, Case Western Reserve University, Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106, USA
| | - Dechen Jiang
- The State Key Laboratory of Analytical Chemistry for Life Science, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Jiangsu 210093, China
| | - Minchul Shin
- Department of Mechanical Engineering, Georgia Southern University, 201 COBA Dr. Statesboro, GA 30458, USA
| | - Thomas Kelley
- Department of Pediatrics and Pharmacology, Case Western Reserve University, Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106, USA
| | - James D Burgess
- Department of Medical Laboratory, Imaging, and Radiologic Sciences, College of Allied Health Sciences, Augusta University and Augusta University Health System, Health Sciences Campus, 987 St. Sabastian Way, EC-2437, Augusta, Georgia 30912 USA
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10
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Gelzo M, Sica C, Elce A, Dello Russo A, Iacotucci P, Carnovale V, Raia V, Salvatore D, Corso G, Castaldo G. Reduced absorption and enhanced synthesis of cholesterol in patients with cystic fibrosis: a preliminary study of plasma sterols. Clin Chem Lab Med 2017; 54:1461-6. [PMID: 26913457 DOI: 10.1515/cclm-2015-1151] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 01/12/2016] [Indexed: 11/15/2022]
Abstract
BACKGROUND Low cholesterol is typically observed in the plasma of patients with cystic fibrosis (CF) contrasting with the subcellular accumulation of cholesterol demonstrated in CF cells and in mice models. However, the homeostasis of cholesterol has not been well investigated in patients with CF. METHODS We studied the plasma of 26 patients with CF and 33 unaffected controls campesterol and β-sitosterol as markers of intestinal absorption and lathosterol as a marker of de novo cholesterol biosynthesis by gas chromatography (GC-FID and GC-MS). RESULTS Plasma campesterol and β-sitosterol results were significantly (p=0.01) lower while plasma lathosterol was significantly higher (p=0.001) in patients with CF as compared to control subjects. Plasma cholesterol results were significantly lower (p=0.01) in CF patients. CONCLUSIONS Our data suggest that the impaired intestinal absorption of exogenous sterols in patients with CF stimulates the endogenous synthesis of cholesterol, but the levels of total cholesterol in plasma remain lower. This may be due to the CFTR dysfunction that reduces cholesterol blood excretion causing the accumulation of cholesterol in liver cells and in other tissues contributing to trigger CF chronic inflammation.
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11
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Rymut SM, Kampman CM, Corey DA, Endres T, Cotton CU, Kelley TJ. Ibuprofen regulation of microtubule dynamics in cystic fibrosis epithelial cells. Am J Physiol Lung Cell Mol Physiol 2016; 311:L317-27. [PMID: 27317686 DOI: 10.1152/ajplung.00126.2016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/12/2016] [Indexed: 11/22/2022] Open
Abstract
High-dose ibuprofen, an effective anti-inflammatory therapy for the treatment of cystic fibrosis (CF), has been shown to preserve lung function in a pediatric population. Despite its efficacy, few patients receive ibuprofen treatment due to potential renal and gastrointestinal toxicity. The mechanism of ibuprofen efficacy is also unclear. We have previously demonstrated that CF microtubules are slower to reform after depolymerization compared with respective wild-type controls. Slower microtubule dynamics in CF cells are responsible for impaired intracellular transport and are related to inflammatory signaling. Here, it is identified that high-dose ibuprofen treatment in both CF cell models and primary CF nasal epithelial cells restores microtubule reformation rates to wild-type levels, as well as induce extension of microtubules to the cell periphery. Ibuprofen treatment also restores microtubule-dependent intracellular transport monitored by measuring intracellular cholesterol transport. These effects are specific to ibuprofen as other cyclooxygenase inhibitors have no effect on these measures. Effects of ibuprofen are mimicked by stimulation of AMPK and blocked by the AMPK inhibitor compound C. We conclude that high-dose ibuprofen treatment enhances microtubule formation in CF cells likely through an AMPK-related pathway. These findings define a potential mechanism to explain the efficacy of ibuprofen therapy in CF.
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Affiliation(s)
- Sharon M Rymut
- Departments of Pediatrics, Case Western Reserve University, Cleveland, Ohio
| | - Claire M Kampman
- Departments of Pediatrics, Case Western Reserve University, Cleveland, Ohio
| | - Deborah A Corey
- Departments of Pediatrics, Case Western Reserve University, Cleveland, Ohio
| | - Tori Endres
- Departments of Pediatrics, Case Western Reserve University, Cleveland, Ohio
| | - Calvin U Cotton
- Departments of Pediatrics, Case Western Reserve University, Cleveland, Ohio
| | - Thomas J Kelley
- Departments of Pediatrics, Case Western Reserve University, Cleveland, Ohio
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12
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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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13
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Manson ME, Corey DA, Bederman I, Burgess JD, Kelley TJ. Regulatory role of β-arrestin-2 in cholesterol processing in cystic fibrosis epithelial cells. J Lipid Res 2012; 53:1268-76. [PMID: 22523395 DOI: 10.1194/jlr.m021972] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cystic fibrosis (CF) cells exhibit an increase in the protein expression of β-arrestin-2 (βarr2) coincident with perinuclear accumulation of free cholesterol. Arrestins are proteins that both serve as broad signaling regulators and contribute to G-protein coupled receptor internalization after agonist stimulation. The hypothesis of this study is that βarr2 is an important component in the mechanisms leading to cholesterol accumulation characteristic of CF cells. To test this hypothesis, epithelial cells stably expressing GFP-tagged βarr2 (βarr2-GFP) and respective GFP-expressing control cells (cont-GFP) were analyzed by filipin staining. The βarr2-GFP cells show a late endosomal/lysosomal cholesterol accumulation that is identical to that seen in CF cells. This βarr2-mediated accumulation is sensitive to Rp-cAMPS treatment, and depleting βarr2 expression in CF-model cells by shRNA alleviates cholesterol accumulation compared with controls. Cftr/βarr2 double knockout mice also exhibit wild-type (WT) levels of cholesterol synthesis, and WT profiles of signaling protein expression have previously been shown to be altered in CF due to cholesterol-related pathways. These data indicate a significant regulatory role for βarr2 in the development of CF-like cholesterol accumulation and give further insight into cholesterol processing mechanisms. An impact of βarr2 expression on Niemann-Pick type C-1 (NPC1)-containing organelle movement is proposed as the mechanism of βarr2-mediated alterations on cholesterol processing. It is concluded that βarr2 expression contributes to altered cholesterol trafficking observed in CF cells.
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Affiliation(s)
- Mary E Manson
- Departments of Chemistry, Case Western Reserve University, Cleveland, OH, USA
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Cianciola NL, Carlin CR, Kelley TJ. Molecular pathways for intracellular cholesterol accumulation: common pathogenic mechanisms in Niemann-Pick disease Type C and cystic fibrosis. Arch Biochem Biophys 2011; 515:54-63. [PMID: 21924233 PMCID: PMC3192251 DOI: 10.1016/j.abb.2011.08.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 08/29/2011] [Accepted: 08/30/2011] [Indexed: 12/11/2022]
Abstract
It has been less than two decades since the underlying genetic defects in Niemann-Pick disease Type C were first identified. These defects impair function of two proteins with a direct role in lipid trafficking, resulting in deposition of free cholesterol within late endosomal compartments and a multitude of effects on cell function and clinical manifestations. The rapid pace of research in this area has vastly improved our overall understanding of intracellular cholesterol homeostasis. Excessive cholesterol buildup has also been implicated in clinical manifestations associated with a number of genetically unrelated diseases including cystic fibrosis. Applying knowledge about anomalous cell signaling behavior in cystic fibrosis opens prospects for identifying similar previously unrecognized disease pathways in Niemann-Pick disease Type C. Recognition that Niemann-Pick disease Type C and cystic fibrosis both impair cholesterol regulatory pathways also provides a rationale for identifying common therapeutic targets.
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Affiliation(s)
- Nicholas L. Cianciola
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4970
| | - Cathleen R. Carlin
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4970
- Case Western Reserve University Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4970
| | - Thomas J. Kelley
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4970
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Abstract
The combination of carbohydrate and lipid generates unusual molecules in which the two distinctive halves of the glycoconjugate influence the function of each other. Membrane glycolipids can act as primary receptors for carbohydrate binding proteins to mediate transmembrane signaling despite restriction to the outer bilayer leaflet. The extensive heterogeneity of the lipid moiety plays a significant, but still largely unknown, role in glycosphingolipid function. Potential interplay between glycolipids and their fatty acid isoforms, together with their preferential interaction with cholesterol, generates a complex mechanism for the regulation of their function in cellular physiology.
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Affiliation(s)
- Clifford A Lingwood
- Research Institute, Hospital for Sick Children, Molecular Structure and Function, Toronto, Ontario M5G 1X8, Canada.
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16
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Manson ME, Corey DA, Rymut SM, Kelley TJ. β-arrestin-2 regulation of the cAMP response element binding protein. Biochemistry 2011; 50:6022-9. [PMID: 21644508 DOI: 10.1021/bi200015h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Previous work demonstrated that cystic fibrosis (CF) cells exhibit an increase in cAMP-mediated signaling as a characteristic response to lost CFTR function. Evidence for increased cAMP-mediated signaling in CF included increased phosphorylation of the cAMP response element binding protein (CREB) and elevated β-arrestin-2 (βarr2) expression. However, subsequent studies reveal that CREB activation in CF cells is independent of protein kinase-A (PKA). The goal of this study is to test the hypothesis that elevated βarr2 expression leads to increased CREB activation in a PKA-independent mechanism. βarr2-GFP expressing tracheal epithelial cells (βarr2-GFP) exhibit an increase of pCREB content and subsequent CRE activation compared to GFP expressing control cells. βarr2 activation of the ERK cascade represents a candidate mechanism leading to CREB activation. ERK exhibits increased activation in βarr2-GFP cells compared to cont-GFP cells, and ERK inhibition diminishes CRE activation in both GFP and βarr2-GFP cells. To test directly whether CREB regulation in CF is βarr2-dependent, nasal epithelium excised from wt mice (Cftr +/+; βarr2 +/+), CF mice (Cftr -/-; βarr2 +/+), and DKO mice (Cftr -/-; βarr2 -/-) were analyzed for pCREB protein content. Removal of βarr2 expression from CF mice reduces both pCREB and pERK content to wt levels. These data indicate that CF-related CREB regulation is mediated directly through βarr2 expression via the ERK pathway.
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Affiliation(s)
- Mary E Manson
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106-4948, USA
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Xu Y, Krause A, Hamai H, Harvey BG, Worgall TS, Worgall S. Proinflammatory phenotype and increased caveolin-1 in alveolar macrophages with silenced CFTR mRNA. PLoS One 2010; 5:e11004. [PMID: 20543983 PMCID: PMC2882373 DOI: 10.1371/journal.pone.0011004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Accepted: 05/15/2010] [Indexed: 11/18/2022] Open
Abstract
The inflammatory milieu in the respiratory tract in cystic fibrosis (CF) has been linked to the defective expression of the cystic transmembrane regulator (CFTR) in epithelial cells. Alveolar macrophages (AM), important contibutors to inflammatory responses in the lung, also express CFTR. The present study analyzes the phenotype of human AM with silenced CFTR. Expression of CFTR mRNA and the immature form of the CFTR protein decreased 100-fold and 5.2-fold, respectively, in AM transfected with a CFTR specific siRNA (CFTR-siRNA) compared to controls. Reduction of CFTR expression in AM resulted in increased secretion of IL-8, increased phosphorylation of NF-κB, a positive regulator of IL-8 expression, and decreased expression of IκB-α, the inhibitory protein of NF-κB activation. AM with silenced CFTR expression also showed increased apoptosis. We hypothesized that caveolin-1 (Cav1), a membrane protein that is co-localized with CFTR in lipid rafts and that is related to inflammation and apoptosis in macrophages, may be affected by decreased CFTR expression. Messenger RNA and protein levels of Cav1 were increased in AM with silenced CFTR. Expression and transcriptional activity of sterol regulatory element binding protein (SREBP), a negative transcriptional regulator of Cav1, was decreased in AM with silenced CFTR, but total and free cholesterol mass did not change. These findings indicate that silencing of CFTR in human AM results in an inflammatory phenotype and apoptosis, which is associated to SREBP-mediated regulation of Cav1.
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Affiliation(s)
- Yaqin Xu
- Department of Pediatrics, Weill Cornell Medical College, New York, New York, United States of America
| | - Anja Krause
- Department of Genetic Medicine, Weill Cornell Medical College, New York, New York, United States of America
| | - Hiroko Hamai
- Department of Pathology, Columbia University, New York, New York, United States of America
| | - Ben-Gary Harvey
- Department of Genetic Medicine, Weill Cornell Medical College, New York, New York, United States of America
| | - Tilla S. Worgall
- Department of Pathology, Columbia University, New York, New York, United States of America
| | - Stefan Worgall
- Department of Pediatrics, Weill Cornell Medical College, New York, New York, United States of America
- Department of Genetic Medicine, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail:
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18
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Fang D, West RH, Manson ME, Ruddy J, Jiang D, Previs SF, Sonawane ND, Burgess JD, Kelley TJ. Increased plasma membrane cholesterol in cystic fibrosis cells correlates with CFTR genotype and depends on de novo cholesterol synthesis. Respir Res 2010; 11:61. [PMID: 20487541 PMCID: PMC2880018 DOI: 10.1186/1465-9921-11-61] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Accepted: 05/20/2010] [Indexed: 01/12/2023] Open
Abstract
Background Previous observations demonstrate that Cftr-null cells and tissues exhibit alterations in cholesterol processing including perinuclear cholesterol accumulation, increased de novo synthesis, and an increase in plasma membrane cholesterol accessibility compared to wild type controls. The hypothesis of this study is that membrane cholesterol accessibility correlates with CFTR genotype and is in part influenced by de novo cholesterol synthesis. Methods Electrochemical detection of cholesterol at the plasma membrane is achieved with capillary microelectrodes with a modified platinum coil that accepts covalent attachment of cholesterol oxidase. Modified electrodes absent cholesterol oxidase serves as a baseline control. Cholesterol synthesis is determined by deuterium incorporation into lipids over time. Incorporation into cholesterol specifically is determined by mass spectrometry analysis. All mice used in the study are on a C57Bl/6 background and are between 6 and 8 weeks of age. Results Membrane cholesterol measurements are elevated in both R117H and ΔF508 mouse nasal epithelium compared to age-matched sibling wt controls demonstrating a genotype correlation to membrane cholesterol detection. Expression of wt CFTR in CF epithelial cells reverts membrane cholesterol to WT levels further demonstrating the impact of CFTR on these processes. In wt epithelial cell, the addition of the CFTR inhibitors, Gly H101 or CFTRinh-172, for 24 h surprisingly results in an initial drop in membrane cholesterol measurement followed by a rebound at 72 h suggesting a feedback mechanism may be driving the increase in membrane cholesterol. De novo cholesterol synthesis contributes to membrane cholesterol accessibility. Conclusions The data in this study suggest that CFTR influences cholesterol trafficking to the plasma membrane, which when depleted, leads to an increase in de novo cholesterol synthesis to restore membrane content.
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Affiliation(s)
- Danjun Fang
- Department of Pediatrics and Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
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19
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Lloyd-Evans E, Platt FM. Lipids on trial: the search for the offending metabolite in Niemann-Pick type C disease. Traffic 2010; 11:419-28. [PMID: 20059748 DOI: 10.1111/j.1600-0854.2010.01032.x] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Niemann-Pick disease type C is a complex lysosomal storage disorder caused by mutations in either the NPC1 or NPC2 genes that is characterized at the cellular level by the storage of multiple lipids, defective lysosomal calcium homeostasis and unique trafficking defects. We review the potential role of each of the individual storage lipids in initiating the pathogenic cascade and propose a model of NPC1 and NPC2 function based on the current knowledge.
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Affiliation(s)
- Emyr Lloyd-Evans
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK.
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20
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Cholon DM, O'Neal WK, Randell SH, Riordan JR, Gentzsch M. Modulation of endocytic trafficking and apical stability of CFTR in primary human airway epithelial cultures. Am J Physiol Lung Cell Mol Physiol 2009; 298:L304-14. [PMID: 20008117 DOI: 10.1152/ajplung.00016.2009] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
CFTR is a highly regulated apical chloride channel of epithelial cells that is mutated in cystic fibrosis (CF). In this study, we characterized the apical stability and intracellular trafficking of wild-type and mutant CFTR in its native environment, i.e., highly differentiated primary human airway epithelial (HAE) cultures. We labeled the apical pool of CFTR and subsequently visualized the protein in intracellular compartments. CFTR moved from the apical surface to endosomes and then efficiently recycled back to the surface. CFTR endocytosis occurred more slowly in polarized than in nonpolarized HAE cells or in a polarized epithelial cell line. The most common mutation in CF, DeltaF508 CFTR, was rescued from endoplasmic reticulum retention by low-temperature incubation but transited from the apical membrane to endocytic compartments more rapidly and recycled less efficiently than wild-type CFTR. Incubation with small-molecule correctors resulted in DeltaF508 CFTR at the apical membrane but did not restore apical stability. To stabilize the mutant protein at the apical membrane, we found that the dynamin inhibitor Dynasore and the cholesterol-extracting agent cyclodextrin dramatically reduced internalization of DeltaF508, whereas the proteasomal inhibitor MG-132 completely blocked endocytosis of DeltaF508. On examination of intrinsic properties of CFTR that may affect its apical stability, we found that N-linked oligosaccharides were not necessary for transport to the apical membrane but were required for efficient apical recycling and, therefore, influenced the turnover of surface CFTR. Thus apical stability of CFTR in its native environment is affected by properties of the protein and modulation of endocytic trafficking.
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Affiliation(s)
- Deborah M Cholon
- Cystic Fibrosis Research Center and Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7248, USA
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21
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Park HJ, Mylvaganum M, McPherson A, Fewell SW, Brodsky JL, Lingwood CA. A soluble sulfogalactosyl ceramide mimic promotes Delta F508 CFTR escape from endoplasmic reticulum associated degradation. ACTA ACUST UNITED AC 2009; 16:461-70. [PMID: 19389632 DOI: 10.1016/j.chembiol.2009.02.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 02/19/2009] [Accepted: 02/25/2009] [Indexed: 10/20/2022]
Abstract
AdaSGC binds Hsc70s to inhibit ATPase activity. Using single-turnover assays, adaSGC, a soluble SGC mimic, preferentially inhibited Hsp40-activated Hsc70 ATP hydrolysis (Ki approximately 10 microM) to reduce C-terminal Hsc70-peptide binding and, potentially, chaperone function. ERAD of misfolded Delta F508 CFTR requires Hsc70-Hsp40 chaperones. In transfected baby hamster kidney (BHK) cells, adaSGC increased Delta F508CFTR ERAD escape, and after low-temperature glycerol rescue, maturation, and iodide efflux. Inhibition of SGC biosynthesis reduced Delta F508CFTR but not wtCFTR expression, whereas depletion of other glycosphingolipids had no affect. WtCFTR transfected BHK cells showed increased SGC synthesis compared with Delta F508CFTR/mock-transfected cells. Partial rescue of Delta F508CFTR by low-temperature glycerol increased SGC synthesis. AdaSGC also increased cellular endogenous SGC levels. SGC in the lung, liver, and kidney was severely depleted in Delta F508CFTR compared with wtCFTR mice, suggesting a role for CFTR in SGC biosynthesis.
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Affiliation(s)
- Hyun-Joo Park
- Research Institute, Division of Molecular Structure and Function, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
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22
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Ribeiro CMP, Hurd H, Wu Y, Martino MEB, Jones L, Brighton B, Boucher RC, O'Neal WK. Azithromycin treatment alters gene expression in inflammatory, lipid metabolism, and cell cycle pathways in well-differentiated human airway epithelia. PLoS One 2009; 4:e5806. [PMID: 19503797 PMCID: PMC2688381 DOI: 10.1371/journal.pone.0005806] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 05/02/2009] [Indexed: 02/07/2023] Open
Abstract
Prolonged macrolide antibiotic therapy at low doses improves clinical outcome in patients affected with diffuse panbronchiolitis and cystic fibrosis. Consensus is building that the therapeutic effects are due to anti-inflammatory, rather than anti-microbial activities, but the mode of action is likely complex. To gain insights into how the macrolide azithromycin (AZT) modulates inflammatory responses in airways, well-differentiated primary cultures of human airway epithelia were exposed to AZT alone, an inflammatory stimulus consisting of soluble factors from cystic fibrosis airways, or AZT followed by the inflammatory stimulus. RNA microarrays were conducted to identify global and specific gene expression changes. Analysis of gene expression changes revealed that the AZT treatment alone altered the gene profile of the cells, primarily by significantly increasing the expression of lipid/cholesterol genes and decreasing the expression of cell cycle/mitosis genes. The increase in cholesterol biosynthetic genes was confirmed by increased filipin staining, an index of free cholesterol, after AZT treatment. AZT also affected genes with inflammatory annotations, but the effect was variable (both up- and down-regulation) and gene specific. AZT pretreatment prevented the up-regulation of some genes, such as MUC5AC and MMP9, triggered by the inflammatory stimulus, but the up-regulation of other inflammatory genes, e.g., cytokines and chemokines, such as interleukin-8, was not affected. On the other hand, HLA genes were increased by AZT. Notably, secreted IL-8 protein levels did not reflect mRNA levels, and were, in fact, higher after AZT pretreatment in cultures exposed to the inflammatory stimulus, suggesting that AZT can affect inflammatory pathways other than by altering gene expression. These findings suggest that the specific effects of AZT on inflamed and non-inflamed airway epithelia are likely relevant to its clinical activity, and their apparent complexity may help explain the diverse immunomodulatory roles of macrolides.
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Affiliation(s)
- Carla Maria P Ribeiro
- Cystic Fibrosis Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
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23
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Abstract
Acid sphingomyelinase occupies a prominent position in sphingolipid catabolism, catalyzing the hydrolysis of sphingomyelin to ceramide and phosphorylcholine. Enzymatic dysfunction of acid sphingomyelinase results in Niemann-Pick disease, a lysosomal storage disorder characterized at the cellular level by accumulation of sphingomyelin within the endo-lysosomal compartment. Over the past decade interest in the role of acid sphingomyelinase has moved beyond its "housekeeping" function in constitutive turnover of sphingomyelin in the lysosome to include study of regulated ceramide generation. Ceramide functions as a bioactive sphingolipid with pleiotropic signaling properties, and has been implicated in diverse cellular processes of physiologic and pathophysiologic importance. Though many cellular enzymes have the capacity to generate ceramide,there is growing appreciation that "all ceramides are not created equal." Ceramides likely exert distinct effects in different cellular/subcellular compartments by virtue of access to other sphingolipid enzymes (e.g.ceramidases), effector molecules (e.g. ceramide-activated protein phosphatases), and neighboring lipids and proteins (e.g. cholesterol, ion channels). One of the unique features of acid sphingomyelinase is that it has been implicated in the hydrolysis of sphingomyelin in three different settings--the endo-lysosomal compartment,the outer leaflet of the plasma membrane, and lipoproteins. How a single gene product has the capacity to function in these diverse settings, and the subsequent impact on downstream ceramide-mediated biology is the subject of this review.
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Affiliation(s)
- Russell W Jenkins
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425, USA.
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24
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Abstract
PURPOSE OF REVIEW Expression of defective cystic fibrosis transmembrane conductance regulator (CFTR), the cause for cystic fibrosis, affects fatty acid, cholesterol and sphingolipid metabolism. This review summarizes recent observations and evaluates current understanding of mechanisms. RECENT FINDINGS Recent observations implicate CFTR, in addition to known effects on fatty acid and cholesterol metabolism, in the regulation of sphingolipid metabolism and suggest that this pathway is relevant to inflammation and infection. A common mechanism on how CFTR affects such a wide spectrum of lipid classes is currently not known. One mechanism for low linoleic acid, amenable to inhibition by docosahexaenoic acid, is increased metabolism in the n-6 fatty acid pathway. Accumulation of free cholesterol in distinct perinuclear compartments, reversible by overexpression of rab9, suggests that cystic fibrosis and the lysosomal storage disease Niemann-Pick-C could share similar cell signaling defects, in addition to increased cAMP signaling and sterol-regulatory element binding protein (SREBP) expression that affect cholesterol metabolism. Novel is the recognition that CFTR modulates ceramide mass and uptake of sphingosine-1- phosphate. Experiments in different cystic fibrosis-mouse models, although not able to establish whether ceramide mass is increased or decreased, suggest that normalization of ceramide decreases infection and selected parameters of inflammation, of relevance to the complex phenotype that characterizes cystic fibrosis. SUMMARY Expression of defective CFTR has profound effects on fatty acid, cholesterol and sphingolipid metabolism, for which mechanisms are currently poorly understood. Recent studies in different cystic fibrosis models suggest a causal relationship between altered ceramide mass and increased inflammation and susceptibility to infection. Studies in cystic fibrosis knockout mouse models suggest that normalization of ceramide decreases infection and inflammation. Studies that evaluate the diagnostic and clinical relevance of sphingolipids in patients with cystic fibrosis are needed.
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Affiliation(s)
- Tilla S Worgall
- Department of Pathology, Pediatrics and Institute of Human Nutrition, Columbia University, BB 457, New York 10032, USA.
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Expression of intestinal and lung alkaline sphingomyelinase and neutral ceramidase in cystic fibrosis f508del transgenic mice. J Pediatr Gastroenterol Nutr 2008; 47:547-54. [PMID: 18955860 DOI: 10.1097/mpg.0b013e3181826daf] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES The intestinal brush border enzymes alkaline sphingomyelinase (alk-SMase) and neutral ceramidase (CDase) digest milk sphingomyelin in suckling neonates. In addition, alk-SMase, CDase, and acid sphingomyelinase (acid-SMase) have been implicated in sphingolipid signaling, which exhibits abnormalities in cystic fibrosis (CF). In this study, we tested the hypothesis that the expression of these enzymes is different in CF. MATERIALS AND METHODS We used mice with F508del (Cftr) mutation, a CF mouse model with well-characterized intestinal pathology. Enzyme activities were measured using radiolabeled sphingolipid substrates incubated with tissue homogenates from different organs and intestinal contents of wild-type mice, homozygous, and heterozygous F508del mice. RESULTS No difference was found in levels of CDase and alk-SMase in the small intestinal mucosa or in their longitudinal distribution. Acid-SMase activity was significantly lower in the mucosa of the distal half of the small intestine of F508del compared with wild-type mice. Despite a lower body weight of F508del mice, length and weight of the small intestine and weight per centimeter of colon were larger than in wild-type. Neutral CDase and alk-SMase activities in lungs were lower than in the gut, whereas acid-SMase activity was comparable in both organs. CDase activity in the spleen was significantly higher in F508del than in wild-type mice. CONCLUSIONS Alk-SMase and neutral CDase are normally expressed in F508del CF mice, whereas activity of acid-SMase in the distal small intestine is decreased. We found no differences in activity of these enzymes in lungs in this mouse model.
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26
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Manson ME, Corey DA, White NM, Kelley TJ. cAMP-mediated regulation of cholesterol accumulation in cystic fibrosis and Niemann-Pick type C cells. Am J Physiol Lung Cell Mol Physiol 2008; 295:L809-19. [PMID: 18790990 DOI: 10.1152/ajplung.90402.2008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The goal of this study was to identify a mechanism regulating cholesterol accumulation in cystic fibrosis (CF) cells. Both CFTR activation and expression are regulated by the cAMP pathway, and it is hypothesized that a feedback response involving this pathway may be involved in the phenotype of cholesterol accumulation. To examine the role of the cAMP pathway in cholesterol accumulation, we treated two CF model cell lines with the Rp diastereomer of adenosine 3',5'-cyclic monophosphorothioate (Rp-cAMPS) and visualized by filipin staining. Rp-cAMPS treatment eliminated cholesterol accumulation in CF cells, whereas 8-bromo-cAMP treatment led to cholesterol accumulation in wild-type cells. To confirm these findings in an independent model system, we also examined the role of cAMP in modulating cholesterol accumulation in Niemann-Pick type C (NPC) fibroblasts. Expression of the protein related to NPC, NPC1, is also directly regulated by cAMP; therefore, it is postulated that NPC cells exhibit the same cAMP-mediated control of cholesterol accumulation. Cholesterol accumulation in NPC cells also was reduced by the presence of Rp-cAMPS. Expression of beta-arrestin-2 (betaarr2), a marker of cellular response to cAMP signaling, was significantly elevated in CF model cells, Cftr(-/-) MNE, primary tissue obtained by nasal scrapes from CF subjects, and in NPC fibroblasts compared with respective controls.
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Affiliation(s)
- Mary E Manson
- Department of Pediatrics, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106-4948, USA
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Lim CH, Bijvelds MJ, Nigg A, Schoonderwoerd K, Houtsmuller AB, de Jonge HR, Tilly BC. Cholesterol Depletion and Genistein as Tools to Promote F508delCFTR Retention at the Plasma Membrane. Cell Physiol Biochem 2008; 20:473-82. [PMID: 17762174 DOI: 10.1159/000107531] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS F508delCFTR-, but not wtCFTR-, expressing fibroblasts resemble Niemann Pick type C cells in the massive intracellular accumulation of free cholesterol. The recruitment and activation of F508delCFTR by cholesterol depletion was studied. METHODS Filipin staining, forskolin-stimulated anion efflux and FITC-dextran uptake were studied in control cells and fibroblasts treated with 2-hydroxypropyl beta-cyclodextrin phosphatidylcholine large unilamellar vesicles to deplete cellular free cholesterol. RESULTS Treatment of F508delCFTR-, but not wtCFTR-, expressing fibroblasts with 2-hydroxypropyl beta-cyclodextrin resulted in a reduction in cellular cholesterol and a potentiation of the forskolin-induced anion efflux. In addition, forskolin also promoted a massive increase in the rate of endocytosis in F508delCFTR fibroblasts, which was absent in genistein- or cyclodextrin-treated cultures. CONCLUSION The results not only suggest that reducing cellular cholesterol may serve as pharmacotherapeutic tool in the treatment of cystic fibrosis but also reveal a novel mechanism for genistein regulation of F508delCFTR, i.e. retention by inhibition of endocytosis.
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Affiliation(s)
- Christina H Lim
- Department of Biochemistry, Erasmus University Medical Center, Rotterdam, The Netherlands
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28
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Ceramide accumulation mediates inflammation, cell death and infection susceptibility in cystic fibrosis. Nat Med 2008; 14:382-91. [PMID: 18376404 DOI: 10.1038/nm1748] [Citation(s) in RCA: 422] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Accepted: 03/04/2008] [Indexed: 01/06/2023]
Abstract
Microbial lung infections are the major cause of morbidity and mortality in the hereditary metabolic disorder cystic fibrosis, yet the molecular mechanisms leading from the mutation of cystic fibrosis transmembrane conductance regulator (CFTR) to lung infection are still unclear. Here, we show that ceramide age-dependently accumulates in the respiratory tract of uninfected Cftr-deficient mice owing to an alkalinization of intracellular vesicles in Cftr-deficient cells. This change in pH results in an imbalance between acid sphingomyelinase (Asm) cleavage of sphingomyelin to ceramide and acid ceramidase consumption of ceramide, resulting in the higher levels of ceramide. The accumulation of ceramide causes Cftr-deficient mice to suffer from constitutive age-dependent pulmonary inflammation, death of respiratory epithelial cells, deposits of DNA in bronchi and high susceptibility to severe Pseudomonas aeruginosa infections. Partial genetic deficiency of Asm in Cftr(-/-)Smpd1(+/-) mice or pharmacological treatment of Cftr-deficient mice with the Asm blocker amitriptyline normalizes pulmonary ceramide and prevents all pathological findings, including susceptibility to infection. These data suggest inhibition of Asm as a new treatment strategy for cystic fibrosis.
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Jiang D, Fang D, Kelley TJ, Burgess JD. Electrochemical analysis of cell plasma membrane cholesterol at the airway surface of mouse trachea. Anal Chem 2008; 80:1235-9. [PMID: 18197693 DOI: 10.1021/ac7019909] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Electrochemical detection of plasma membrane cholesterol at the surface of excised mouse trachea tissue is reported. Cholesterol oxidase is covalently linked to an 11-mercaptoundecanoic acid submonolayer on the platinum electrode surface. The cholesterol oxidase-modified electrodes show steady-state responses for cholesterol in solution at physiological temperatures. Experiments for direct contact between the cholesterol oxidase-modified electrode and the surface of excised trachea tissue at 37 degrees C indicate steady-state responses that are largely independent of the position of contact on the tissue surface. Tissue samples are mounted on a quartz crystal microbalance electrode to gauge contact force between the electrode and the tissue surface, and the steady-state electrode response for tissue cholesterol is shown to be largely independent of the contact force. Trachea tissue excised from a mouse model of cystic fibrosis, which is known to exhibit evaluated cholesterol in airway cells, shows an electrode response that is approximately 40% larger than the response observed at wild-type mouse trachea tissue.
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Affiliation(s)
- Dechen Jiang
- Department of Chemistry, Case Western Reserve University and Rainbow Babies and Children's Hospital, Cleveland, OH 44106, USA
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30
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Corey DA, Kelley TJ. Elevated small GTPase activation influences the cell proliferation signaling control in Niemann-Pick type C fibroblasts. Biochim Biophys Acta Mol Basis Dis 2007; 1772:748-54. [PMID: 17499483 DOI: 10.1016/j.bbadis.2007.03.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Revised: 02/06/2007] [Accepted: 03/26/2007] [Indexed: 01/24/2023]
Abstract
Niemann-Pick type C (NPC) disease is characterized at the cellular level by the intracellular accumulation of free cholesterol. We have previously identified a similar phenotype in cystic fibrosis (CF) cell models that results in the activation of the small GTPase RhoA. The hypothesis of this study was that NPC cells would also exhibit an increase in small GTPase activation. An examination of the active, GTP-bound form of GTPases revealed a basal increase in the content of the active-form Ras and RhoA small GTPases in NPC fibroblasts compared to wt controls. To assess whether this increase in GTP-bound Ras and RhoA manifests a functional outcome, the expression of the proliferation control proteins p21/waf1 and cyclin D were examined. Consistent with increased GTPase signaling, p21/waf1 expression is reduced and cyclin D expression is elevated in NPC fibroblasts. Interestingly, cell growth rate is not altered in NPC fibroblasts compared to wt cells. However, NPC sensitivity to statin treatment is reversed by addition of the isoprenoid geranylgeranyl pyrophosphate (GGPP), a modifier of RhoA. It is concluded that Ras and RhoA basal activation is elevated in NPC fibroblasts and has an impact on cell survival pathways.
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Affiliation(s)
- Deborah A Corey
- Department of Pediatrics, Case Western Reserve University and Rainbow Babies and Children's Hospital, 8th floor BRB, 10900 Euclid Ave., Cleveland, OH 44106-4948, USA
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Gentzsch M, Choudhury A, Chang XB, Pagano RE, Riordan JR. Misassembled mutant DeltaF508 CFTR in the distal secretory pathway alters cellular lipid trafficking. J Cell Sci 2007; 120:447-55. [PMID: 17213331 DOI: 10.1242/jcs.03350] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Most patients with cystic fibrosis (CF) have a single codon deletion (DeltaF508) in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) that impairs assembly of the multidomain glycoprotein. The mutant protein escapes endoplasmic reticulum (ER) quality control at low temperature, but is rapidly cleared from the distal secretory pathway and degraded in lysosomes. CF cells accumulate free cholesterol similar to Niemann-Pick disease type C cells. We show that this lipid alteration is caused by the presence of misassembled mutant CFTR proteins, including DeltaF508, in the distal secretory pathway rather than the absence of functional CFTR. By contrast, cholesterol distribution is not changed by either D572N CFTR, which does not mature even at low temperature, or G551D, which is processed normally but is inactive. On expression of the DeltaF508 mutant, cholesterol and glycosphingolipids accumulate in punctate endosomal structures and cholesterol esters are reduced, indicating a block in the translocation of cholesterol to the ER for esterification. This is overcome by Rab9 overexpression, resulting in clearance of accumulating intracellular cholesterol. Similar but less pronounced alterations in intracellular cholesterol distribution are observed on expression of a temperature-rescued mutant variant of the related ATP-binding cassette (ABC) protein multidrug resistance-associated protein 1 (MRP1). Thus, on escape from ER quality control, misassembled mutants of CFTR and MRP1 impair lipid homeostasis in endocytic compartments.
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Affiliation(s)
- Martina Gentzsch
- Department of Cell and Developmental Biology and Cystic Fibrosis Research Center, University of North Carolina, Chapel Hill, NC 27599, USA.
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White NM, Jiang D, Burgess JD, Bederman IR, Previs SF, Kelley TJ. Altered cholesterol homeostasis in cultured and in vivo models of cystic fibrosis. Am J Physiol Lung Cell Mol Physiol 2006; 292:L476-86. [PMID: 17085523 DOI: 10.1152/ajplung.00262.2006] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Determining how the regulation of cellular processes is impacted in cystic fibrosis (CF) is fundamental to understanding disease pathology and to identifying new therapeutic targets. In this study, unesterified cholesterol accumulation is observed in lung and trachea sections obtained from CF patients compared with non-CF tissues, suggesting an inherent flaw in cholesterol processing. An alternate staining method utilizing a fluorescent cholesterol probe also indicates improper lysosomal storage of cholesterol in CF cells. Excess cholesterol is also manifested by a significant increase in plasma membrane cholesterol content in both cultured CF cells and in nasal tissue excised from cftr(-/-) mice. Impaired intracellular cholesterol movement is predicted to stimulate cholesterol synthesis, a hypothesis supported by the observation of increased de novo cholesterol synthesis in lung and liver of cftr(-/-) mice compared with controls. Furthermore, pharmacological inhibition of cholesterol transport is sufficient to cause CF-like elevation in cytokine production in wild-type cells in response to bacterial challenge but has no effect in CF cells. These data demonstrate via multiple methods in both cultured and in vivo models that cellular cholesterol homeostasis is inherently altered in CF. This perturbation of cholesterol homeostasis represents a potentially important process in CF pathogenesis.
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Affiliation(s)
- Nicole M White
- Department of Pediatrics and Pharmacology, Case Western Reserve University and Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106, USA
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Chang TY, Reid PC, Sugii S, Ohgami N, Cruz JC, Chang CCY. Niemann-Pick type C disease and intracellular cholesterol trafficking. J Biol Chem 2005; 280:20917-20. [PMID: 15831488 DOI: 10.1074/jbc.r400040200] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Ta-Yuan Chang
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
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