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Lei XH, Bochner BR. Optimization of cell permeabilization in electron flow based mitochondrial function assays. Free Radic Biol Med 2021; 177:48-57. [PMID: 34656699 DOI: 10.1016/j.freeradbiomed.2021.10.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 10/05/2021] [Accepted: 10/13/2021] [Indexed: 12/21/2022]
Abstract
Permeable cell models have contributed much to the progress in mitochondrial research. Optimization of permeabilization is required to make the cell's plasma membrane permeable to small molecules while keeping the intracellular organelles and their membranes intact and fully functional. Here we report our assessment and optimization of commonly used permeabilizing agents including different saponin preparations, digitonin, and recombinant perfringolysin O employing a new electron flow based mitochondrial assay technology that utilizes a colorimetric redox dye. The results of this study provide guidance in optimizing the conditions for mitochondrial function assays with permeabilized cells using the novel redox dye-based format.
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Affiliation(s)
- Xiang-He Lei
- Biolog, Inc., 21124 Cabot Blvd., Hayward, CA, 94545, USA
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2
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Lotz-Havla AS, Weiß KJ, Schiergens KA, Brunet T, Kohlhase J, Regenauer-Vandewiele S, Maier EM. Subcutaneous vitamin B12 administration using a portable infusion pump in cobalamin-related remethylation disorders: a gentle and easy to use alternative to intramuscular injections. Orphanet J Rare Dis 2021; 16:215. [PMID: 33980297 PMCID: PMC8114704 DOI: 10.1186/s13023-021-01847-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 05/04/2021] [Indexed: 12/03/2022] Open
Abstract
Background Cobalamin (cbl)-related remethylation disorders are a heterogeneous group of inherited disorders comprising the remethylation of homocysteine to methionine and affecting multiple organ systems, most prominently the nervous system and the bone marrow. To date, the parenteral, generally intramuscular, lifelong administration of hydroxycobalamin (OHCbl) is the mainstay of therapy in these disorders. The dosage and frequency of OHCbl is titrated in each patient to the minimum effective dose in order to account for the painful injections. This may result in undertreatment, a possible risk factor for disease progression and disease-related complications. Results We describe parenteral administration of OHCbl using a subcutaneous catheter together with a portable infusion pump in a home therapy setting in four pediatric patients with remethylation disorders, two patients with cblC, one patient with cblG, and one patient with cblE deficiency, in whom intramuscular injections were not or no longer feasible. The placement of the subcutaneous catheters and handling of the infusion pump were readily accomplished and well accepted by the patients and their families. No adverse events occurred. The use of a small, portable syringe driver pump allowed for a most flexible administration of OHCbl in everyday life. The concentrations of total homocysteine levels were determined at regular patient visits and remained within the therapeutic target range. This approach allowed for the continuation of OHCbl therapy or the adjustment of therapy required to improve metabolic control in our patients. Conclusions Subcutaneous infusion using a subcutaneous catheter system and a portable pump for OHCbl administration in combined and isolated remethylation disorders is safe, acceptable, and effective. It decreases disease burden in preventing frequent single injections and providing patient independence. Thus, it may promote long-term adherence to therapy in patients and parents.
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Affiliation(s)
- Amelie S Lotz-Havla
- Department of Inborn Errors of Metabolism, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Lindwurmstr. 4, 80337, Munich, Germany
| | - Katharina J Weiß
- Department of Inborn Errors of Metabolism, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Lindwurmstr. 4, 80337, Munich, Germany
| | - Katharina A Schiergens
- Department of Inborn Errors of Metabolism, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Lindwurmstr. 4, 80337, Munich, Germany
| | - Theresa Brunet
- Institute of Human Genetics, Technische Universität München, Trogerstr. 32, 81675, Munich, Germany
| | - Jürgen Kohlhase
- SYNLAB Center for Human Genetics, Heinrich-von-Stephan-Str. 5, 79100, Freiburg, Germany
| | - Stephanie Regenauer-Vandewiele
- Department of Inborn Errors of Metabolism, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Lindwurmstr. 4, 80337, Munich, Germany
| | - Esther M Maier
- Department of Inborn Errors of Metabolism, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Lindwurmstr. 4, 80337, Munich, Germany.
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Cao B, Chen Y, McIntyre RS, Yan L. Acyl-Carnitine plasma levels and their association with metabolic syndrome in individuals with schizophrenia. Psychiatry Res 2020; 293:113458. [PMID: 32977055 DOI: 10.1016/j.psychres.2020.113458] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Accepted: 09/13/2020] [Indexed: 02/06/2023]
Abstract
The metabolic syndrome (MetS) affects individuals with schizophrenia at a higher rate when compared to individuals in the general population. Accumulating evidence indicated that subjects with MetS generally manifest elevated levels of acyl-carnitines, which are important carriers for transporting fatty acyl group. Abnormalities of acyl-carnitines in individuals with schizophrenia with or without MetS had not been sufficiently characterized. We conducted this post-hoc analysis with our published data to further evaluate the differences of 29 acyl-carnitines in 46 individuals with schizophrenia with MetS and 123 without MetS. The rate of MetS was 27.2% (46/169) in the individuals with schizophrenia. After FDR correction, the individuals with schizophrenia and MetS showed significantly higher levels of 17 plasma acyl-carnitines, compared to individuals without MetS. Eight acyl-carnitines (i.e., C3, C4, C5, C6: 1, C10: 1, C10: 2, C14: 2-OH, C16: 2-OH) were significantly different between two groups after adjusting for age and sex. The correlation analysis reported that acyl-carnitine concentrations have potential correlations with certain metabolic parameters. Our findings provide valuable new clues for exploring the roles of acyl-carnitines in the diagnosis and treatment of schizophrenia. More data and molecular biology evidences are needed to replicate our findings and elucidate relevant mechanisms.
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Affiliation(s)
- Bing Cao
- School of Psychology and Key Laboratory of Cognition and Personality (Ministry of Education), Southwest University, Chongqing 400715, China; National Demonstration Center for Experimental Psychology Education, Southwest University, Chongqing 400715, China.
| | - Yan Chen
- Dalla Lana School of Public Health, University of Toronto. 155 College St., Toronto, ON, Canada
| | - Roger S McIntyre
- Mood Disorders Psychopharmacology Unit, Toronto Western Hospital, University Health Network, Toronto, ON, Canada; Brain and Cognition Discovery Foundation, Toronto, ON, Canada
| | - Lailai Yan
- Department of Laboratorial Science and Technology, School of Public Health, Peking University, Beijing 100191, P. R. China; Medical and Health Analysis Center, Peking University, Beijing 100191, P. R. China; Vaccine Research Center, School of Public Health, Peking University, Beijing 100191, P. R. China.
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Zhou Y, Tan Y, Hou G, Ren Y, Deng Y, Yan K, Zhang Y, Lin L, Lou X, Liu S. Pathway attenuation of fatty acid beta-oxidation in the skeletal muscle of a type 2 diabetic mouse model. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8869. [PMID: 32562559 DOI: 10.1002/rcm.8869] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 05/21/2020] [Accepted: 06/09/2020] [Indexed: 06/11/2023]
Abstract
RATIONALE Whether catabolic abnormalities of fatty acids exist in the skeletal muscle of type 2 diabetes mellitus (T2DM) has not been determined. In this study, we postulated that a systematic evaluation of the protein abundance and metabolic activity related to fatty acids in the skeletal muscle tissues of a T2DM mouse model was feasible to address this question. METHODS Mitochondria were extracted from wild-type (WT) and db/db mice followed by quantitative analysis of the proteins involved in mitochondrial fatty acid oxidation (mFAO). The pathway activity of mFAO in skeletal muscle tissues was monitored in vitro using mass spectrometry, and tissue lipidomic analysis was conducted in profiling and target mode to distinguish the levels of long-chain acylcarnitines between WT and db/db mice. RESULTS Two proteins related to the mFAO pathway were significantly downregulated in the skeletal muscle mitochondria of db/db mice. The measurement of mFAO pathway activity in vitro revealed that the abundance of long-chain acylcarnitines (C14 to C18) in db/db mice was lower than that in WT mice, and the determination of acylcarnitines in skeletal muscle tissues in vivo revealed that most long-chain acylcarnitines were decreased in db/db mice. CONCLUSIONS The findings of lower abundance of ACAD9 and CPT1B, reduced activity of the mFAO pathway in vitro and decreased acylcarnitines in vivo firmly support that the mFAO pathway in the skeletal muscle of diabetic mice is attenuated, possibly resulting in cell/tissue dysfunction in diabetes.
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Affiliation(s)
- Yang Zhou
- BGI-Shenzhen, Shenzhen, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Yifan Tan
- BGI-Shenzhen, Shenzhen, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Guixue Hou
- BGI-Shenzhen, Shenzhen, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Yan Ren
- BGI-Shenzhen, Shenzhen, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Yamei Deng
- BGI-Shenzhen, Shenzhen, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Keqiang Yan
- BGI-Shenzhen, Shenzhen, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Yue Zhang
- BGI-Shenzhen, Shenzhen, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Liang Lin
- BGI-Shenzhen, Shenzhen, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Xiaomin Lou
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
| | - Siqi Liu
- BGI-Shenzhen, Shenzhen, China
- China National GeneBank, BGI-Shenzhen, Shenzhen, China
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Matejka K, Stückler F, Salomon M, Ensenauer R, Reischl E, Hoerburger L, Grallert H, Kastenmüller G, Peters A, Daniel H, Krumsiek J, Theis FJ, Hauner H, Laumen H. Dynamic modelling of an ACADS genotype in fatty acid oxidation - Application of cellular models for the analysis of common genetic variants. PLoS One 2019; 14:e0216110. [PMID: 31120904 PMCID: PMC6532850 DOI: 10.1371/journal.pone.0216110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 04/15/2019] [Indexed: 11/19/2022] Open
Abstract
Background Genome-wide association studies of common diseases or metabolite quantitative traits often identify common variants of small effect size, which may contribute to phenotypes by modulation of gene expression. Thus, there is growing demand for cellular models enabling to assess the impact of gene regulatory variants with moderate effects on gene expression. Mitochondrial fatty acid oxidation is an important energy metabolism pathway. Common noncoding acyl-CoA dehydrogenase short chain (ACADS) gene variants are associated with plasma C4-acylcarnitine levels and allele-specific modulation of ACADS expression may contribute to the observed phenotype. Methods and findings We assessed ACADS expression and intracellular acylcarnitine levels in human lymphoblastoid cell lines (LCL) genotyped for a common ACADS variant associated with plasma C4-acylcarnitine and found a significant genotype-dependent decrease of ACADS mRNA and protein. Next, we modelled gradual decrease of ACADS expression using a tetracycline-regulated shRNA-knockdown of ACADS in Huh7 hepatocytes, a cell line with high fatty acid oxidation-(FAO)-capacity. Assessing acylcarnitine flux in both models, we found increased C4-acylcarnitine levels with decreased ACADS expression levels. Moreover, assessing time-dependent changes of acylcarnitine levels in shRNA-hepatocytes with altered ACADS expression levels revealed an unexpected effect on long- and medium-chain fatty acid intermediates. Conclusions Both, genotyped LCL and regulated shRNA-knockdown are valuable tools to model moderate, gradual gene-regulatory effects of common variants on cellular phenotypes. Decreasing ACADS expression levels modulate short and surprisingly also long/medium chain acylcarnitines, and may contribute to increased plasma acylcarnitine levels.
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Affiliation(s)
- Kerstin Matejka
- Chair of Nutritional Medicine, Else Kröner-Fresenius-Center for Nutritional Medicine, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
- ZIEL-Research Center for Nutrition and Food Sciences, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Clinical Cooperation Group Nutrigenomics and Type 2 Diabetes, Helmholtz Zentrum München, Neuherberg, Germany
- Clinical Cooperation Group Nutrigenomics and Type 2 Diabetes, Technische Universität München, Freising-Weihenstephan, Germany
| | - Ferdinand Stückler
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | | | - Regina Ensenauer
- Research Center, Dr. von Hauner Children’s Hospital, Ludwig-Maximilians-Universität München, München, Germany
- Experimental Pediatrics and Metabolism, Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children’s Hospital, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Institute of Child Nutrition, Max Rubner-Institut, Karlsruhe, Germany
| | - Eva Reischl
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Lena Hoerburger
- Paediatric Nutritional Medicine, Else Kröner-Fresenius-Centre for Nutritional Medicine, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
| | - Harald Grallert
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Clinical Cooperation Group Nutrigenomics and Type 2 Diabetes, Helmholtz Zentrum München, Neuherberg, Germany
- Clinical Cooperation Group Nutrigenomics and Type 2 Diabetes, Technische Universität München, Freising-Weihenstephan, Germany
- Research Unit of Molecular Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Gabi Kastenmüller
- Institute of Bioinformatics and Systems Biology, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Annette Peters
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Institute of Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
- German Research Center for Cardiovascular Disease (DZHK-Munich partner site), Neuherberg, Germany
| | - Hannelore Daniel
- ZIEL-Research Center for Nutrition and Food Sciences, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
- Chair of Physiology of Human Nutrition, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
| | - Jan Krumsiek
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
- Institute for Computational Biomedicine, Englander Institute for Precision Medicine, Department of Physiology and Biophysics, Weill Cornell Medicine, New York, United States of America
| | - Fabian J. Theis
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
- Department of Mathematical Science, Technische Universität München, Garching, Germany
- * E-mail: (FJT); (HL)
| | - Hans Hauner
- Chair of Nutritional Medicine, Else Kröner-Fresenius-Center for Nutritional Medicine, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
- ZIEL-Research Center for Nutrition and Food Sciences, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Clinical Cooperation Group Nutrigenomics and Type 2 Diabetes, Helmholtz Zentrum München, Neuherberg, Germany
- Clinical Cooperation Group Nutrigenomics and Type 2 Diabetes, Technische Universität München, Freising-Weihenstephan, Germany
- Else Kröner-Fresenius-Center for Nutritional Medicine, Klinikum rechts der Isar, Technische Universität München, München, Germany
| | - Helmut Laumen
- Chair of Nutritional Medicine, Else Kröner-Fresenius-Center for Nutritional Medicine, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
- ZIEL-Research Center for Nutrition and Food Sciences, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- Clinical Cooperation Group Nutrigenomics and Type 2 Diabetes, Helmholtz Zentrum München, Neuherberg, Germany
- Clinical Cooperation Group Nutrigenomics and Type 2 Diabetes, Technische Universität München, Freising-Weihenstephan, Germany
- Paediatric Nutritional Medicine, Else Kröner-Fresenius-Centre for Nutritional Medicine, TUM School of Life Sciences Weihenstephan, Technische Universität München, Freising-Weihenstephan, Germany
- Institute of Experimental Genetics, Helmholtz Zentrum München, Neuherberg, Germany
- Research Unit Protein Science, Helmholtz Zentrum München, Neuherberg, Germany
- * E-mail: (FJT); (HL)
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Characterizing acyl-carnitine biosignatures for schizophrenia: a longitudinal pre- and post-treatment study. Transl Psychiatry 2019; 9:19. [PMID: 30655505 PMCID: PMC6336814 DOI: 10.1038/s41398-018-0353-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/18/2018] [Accepted: 11/08/2018] [Indexed: 12/21/2022] Open
Abstract
Subjects with schizophrenia have high risks of metabolic abnormalities and bioenergetic dysfunction. Acyl-carnitines involved in bioenergetic pathways provide potential biomarker targets for identifying early changes and onset characteristics in subjects with schizophrenia. We measured 29 acyl-carnitine levels within well-characterized plasma samples of adults with schizophrenia and healthy controls using liquid chromatography-mass spectrometry (LC-MS). Subjects with schizophrenia were measured at baseline and after 8 weeks of treatment. A total of 225 subjects with schizophrenia and 175 age- and gender-matched healthy controls were enrolled and 156 subjects completed the 8-week follow-up. With respect to plasma acyl-carnitines, the individuals with schizophrenia at baseline showed significantly higher levels of C4-OH (C3-DC) and C16:1, but lower concentrations of C3, C8, C10, C10:1, C10:2, C12, C14:1-OH, C14:2, and C14:2-OH when compared with healthy controls after controlling for age, sex, body mass index (BMI), smoking, and drinking. For the comparison between pretreatment and posttreatment subjects, all detected acyl-carnitines were significantly different between the two groups. Only the concentration of C3 and C4 were increased after selection by variable importance in projection (VIP) value >1.0 and false discovery rate (FDR) q value <0.05. A panel of acyl-carnitines were selected for the ability to differentiate subjects of schizophrenia at baseline from controls, pre- from post-treatment, and posttreatment from controls. Our data implicated acyl-carnitines with abnormalities in cellular bioenergetics of schizophrenia. Therefore, acyl-carnitines can be potential targets for future investigations into their roles in the pathoetiology of schizophrenia.
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Maimouni S, Issa N, Cheng S, Ouaari C, Cheema A, Kumar D, Byers S. Tumor suppressor RARRES1- A novel regulator of fatty acid metabolism in epithelial cells. PLoS One 2018; 13:e0208756. [PMID: 30557378 PMCID: PMC6296515 DOI: 10.1371/journal.pone.0208756] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 11/20/2018] [Indexed: 12/31/2022] Open
Abstract
Retinoic acid receptor responder 1 (RARRES1) is silenced in many cancers and is differentially expressed in metabolism associated diseases, such as hepatic steatosis, hyperinsulinemia and obesity. Here we report a novel function of RARRES1 in metabolic reprogramming of epithelial cells. Using non-targeted LC-MS, we discovered that RARRES1 depletion in epithelial cells caused a global increase in lipid synthesis. RARRES1-depleted cells rewire glucose metabolism by switching from aerobic glycolysis to glucose-dependent de novo lipogenesis (DNL). Treatment with fatty acid synthase (FASN) inhibitor, C75, reversed the effects of RARRES1 depletion. The increased DNL in RARRES1-depleted normal breast and prostate epithelial cells proved advantageous to the cells during starvation, as the increase in fatty acid availability lead to more oxidized fatty acids (FAO), which were used for mitochondrial respiration. Expression of RARRES1 in several common solid tumors is also contextually correlated with expression of fatty acid metabolism genes and fatty acid-regulated transcription factors. Pathway enrichment analysis led us to determine that RARRES1 is regulated by peroxisome proliferating activated receptor (PPAR) signaling. These findings open up a new avenue for metabolic reprogramming and identify RARRES1 as a potential target for cancers and other diseases with impaired fatty acid metabolism.
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Affiliation(s)
- Sara Maimouni
- Department of Biochemical, Molecular and Cellular Biology, Georgetown University, Washington, District of Columbia, United States of America
| | - Naiem Issa
- Georgetown-Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, Washington, District of Columbia, United States of America
| | - Selina Cheng
- Georgetown-Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, Washington, District of Columbia, United States of America
| | - Chokri Ouaari
- Georgetown-Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, Washington, District of Columbia, United States of America
- University of the District of Columbia, Washington, District of Columbia, United States of America
| | - Amrita Cheema
- Georgetown-Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, Washington, District of Columbia, United States of America
| | - Deepak Kumar
- Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina, United States of America
| | - Stephen Byers
- Department of Biochemical, Molecular and Cellular Biology, Georgetown University, Washington, District of Columbia, United States of America
- Georgetown-Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University, Washington, District of Columbia, United States of America
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Guder P, Lotz-Havla AS, Woidy M, Reiß DD, Danecka MK, Schatz UA, Becker M, Ensenauer R, Pagel P, Büttner L, Muntau AC, Gersting SW. Isoform-specific domain organization determines conformation and function of the peroxisomal biogenesis factor PEX26. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1866:518-531. [PMID: 30366024 DOI: 10.1016/j.bbamcr.2018.10.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 10/11/2018] [Accepted: 10/18/2018] [Indexed: 10/28/2022]
Abstract
Peroxisomal biogenesis factor PEX26 is a membrane anchor for the multi-subunit PEX1-PEX6 protein complex that controls ubiquitination and dislocation of PEX5 cargo receptors for peroxisomal matrix protein import. PEX26 associates with the peroxisomal translocation pore via PEX14 and a splice variant (PEX26Δex5) of unknown function has been reported. Here, we demonstrate PEX26 homooligomerization mediated by two heptad repeat domains adjacent to the transmembrane domain. We show that isoform-specific domain organization determines PEX26 oligomerization and impacts peroxisomal β-oxidation and proliferation. PEX26 and PEX26Δex5 displayed different patterns of interaction with PEX2-PEX10 or PEX13-PEX14 complexes, which relate to distinct pre-peroxisomes in the de novo synthesis pathway. Our data support an alternative PEX14-dependent mechanism of peroxisomal membrane association for the splice variant, which lacks a transmembrane domain. Structure-function relationships of PEX26 isoforms explain an extended function in peroxisomal homeostasis and these findings may improve our understanding of the broad phenotype of PEX26-associated human disorders.
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Affiliation(s)
- Philipp Guder
- University Children's Research@Kinder-UKE, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Amelie S Lotz-Havla
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany
| | - Mathias Woidy
- University Children's Research@Kinder-UKE, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Dunja D Reiß
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany
| | - Marta K Danecka
- University Children's Research@Kinder-UKE, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Ulrich A Schatz
- Department for Medical Genetics, Molecular and Clinical Pharmacology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Marc Becker
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany; Labor Becker Olgemöller und Kollegen, 81671 Munich, Germany
| | - Regina Ensenauer
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany; Experimental Pediatrics, Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Philipp Pagel
- Lehrstuhl für Genomorientierte Bioinformatik, Technische Universität, 85350 Freising, Germany; numares GmbH, Josef-Engert-Str. 9, 93053 Regensburg, Germany
| | - Lars Büttner
- Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, 80337 Munich, Germany
| | - Ania C Muntau
- Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Søren W Gersting
- University Children's Research@Kinder-UKE, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
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9
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Grünig D, Duthaler U, Krähenbühl S. Effect of Toxicants on Fatty Acid Metabolism in HepG2 Cells. Front Pharmacol 2018; 9:257. [PMID: 29740314 PMCID: PMC5924803 DOI: 10.3389/fphar.2018.00257] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 03/07/2018] [Indexed: 12/11/2022] Open
Abstract
Impairment of hepatic fatty acid metabolism can lead to liver steatosis and injury. Testing drugs for interference with hepatic fatty acid metabolism is therefore important. To find out whether HepG2 cells are suitable for this purpose, we investigated the effect of three established fatty acid metabolism inhibitors and of three test compounds on triglyceride accumulation, palmitate metabolism, the acylcarnitine pool and dicarboxylic acid accumulation in the cell supernatant and on ApoB-100 excretion in HepG2 cells. The three established inhibitors [etomoxir, methylenecyclopropylacetic acid (MCPA), and 4-bromocrotonic acid (4-BCA)] depleted mitochondrial ATP at lower concentrations than cytotoxicity occurred, suggesting mitochondrial toxicity. They inhibited palmitate metabolism at similar or lower concentrations than ATP depletion, and 4-BCA was associated with cellular fat accumulation. They caused specific changes in the acylcarnitine pattern and etomoxir an increase of thapsic (C18 dicarboxylic) acid in the cell supernatant, and did not interfere with ApoB-100 excretion (marker of VLDL export). The three test compounds (amiodarone, tamoxifen, and the cannabinoid WIN 55,212-2) depleted the cellular ATP content at lower concentrations than cytotoxicity occurred. They all caused cellular fat accumulation and inhibited palmitate metabolism at similar or higher concentrations than ATP depletion. They suppressed medium-chain acylcarnitines in the cell supernatant and amiodarone and tamoxifen impaired thapsic acid production. Tamoxifen and WIN 55,212-2 decreased cellular ApoB-100 excretion. In conclusion, the established inhibitors of fatty acid metabolism caused the expected effects in HepG2 cells. HepG cells proved to be useful for the detection of drug-associated toxicities on hepatocellular fatty acid metabolism.
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Affiliation(s)
- David Grünig
- Division of Clinical Pharmacology and Toxicology, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Urs Duthaler
- Division of Clinical Pharmacology and Toxicology, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Stephan Krähenbühl
- Division of Clinical Pharmacology and Toxicology, University Hospital Basel, Basel, Switzerland.,Department of Biomedicine, University of Basel, Basel, Switzerland.,Swiss Centre for Applied Human Toxicology, Basel, Switzerland
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Grünig D, Felser A, Duthaler U, Bouitbir J, Krähenbühl S. Effect of the Catechol-O-Methyltransferase Inhibitors Tolcapone and Entacapone on Fatty Acid Metabolism in HepaRG Cells. Toxicol Sci 2018; 164:477-488. [DOI: 10.1093/toxsci/kfy101] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- David Grünig
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, 4031 Basel, Switzerland
- Department of Biomedicine, University of Basel, 4031 Basel, Switzerland
| | - Andrea Felser
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, 4031 Basel, Switzerland
- Department of Biomedicine, University of Basel, 4031 Basel, Switzerland
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, 4031 Basel, Switzerland
| | - Urs Duthaler
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, 4031 Basel, Switzerland
- Department of Biomedicine, University of Basel, 4031 Basel, Switzerland
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, 4031 Basel, Switzerland
| | - Jamal Bouitbir
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, 4031 Basel, Switzerland
- Department of Biomedicine, University of Basel, 4031 Basel, Switzerland
- Swiss Center for Applied Human Toxicology (SCAHT), 4055 Basel, Switzerland
| | - Stephan Krähenbühl
- Division of Clinical Pharmacology & Toxicology, University Hospital Basel, 4031 Basel, Switzerland
- Department of Biomedicine, University of Basel, 4031 Basel, Switzerland
- Swiss Center for Applied Human Toxicology (SCAHT), 4055 Basel, Switzerland
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Regulation of mitochondrial fatty acid β-oxidation in human: what can we learn from inborn fatty acid β-oxidation deficiencies? Biochimie 2013; 96:113-20. [PMID: 23764392 DOI: 10.1016/j.biochi.2013.05.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 05/30/2013] [Indexed: 12/31/2022]
Abstract
The mitochondrial fatty acid β-oxidation (FAO) pathway plays a crucial role in ATP production in many tissues with high-energy demand. This is highlighted by the diverse and possibly severe clinical manifestations of inborn fatty acid β-oxidation deficiencies. More than fifteen genetic FAO enzyme defects have been described to date, forming a large group of rare diseases. Inborn FAO disorders are characterized by a high genetic heterogeneity, with a variety of gene mutations resulting in complete or partial loss-of-function of the corresponding enzyme. The panel of observed phenotypes varies from multi-organ failure in the neonate with fatal outcome, up to milder late onset manifestations associated with significant disabilities. Diagnosis of FAO disorders has markedly improved over the last decades, but few treatments are available. The clinical, biochemical, and molecular analysis of these disorders provided new, and sometimes unexpected, data on the organization and regulation of mitochondrial FAO in humans, in various tissues, and at various stages of development. This will be illustrated by examples of FAO defects affecting enzymes of long-chain fatty acid import into the mitochondria, or Lynen helix enzymes. The involvement of the transcriptional network regulating FAO gene expression, in particular the PGC-1α/PPAR axis, as a target for pharmacological therapy of these genetic disorders, will also be discussed.
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Ye F, Hoppel CL. Measuring oxidative phosphorylation in human skin fibroblasts. Anal Biochem 2013; 437:52-8. [PMID: 23462540 DOI: 10.1016/j.ab.2013.02.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 02/12/2013] [Accepted: 02/13/2013] [Indexed: 12/21/2022]
Abstract
An approach has been developed to quantitate oxidative phosphorylation in harvested human skin fibroblasts that have been permeabilized with digitonin. In protocol 1, state 3 rates are measured with complex I and II substrates, followed by uncoupled maximal oxidative capacity measured in the presence of these combined substrates as well as through complex IV. In protocol 2, state 3 rates are measured using palmitoylcarnitine to monitor fatty acid oxidation and duroquinol to assess the flux through complex III; uncoupled duroquinol oxidation measures maximal oxidative capacity through complex III. The activity of citrate synthase is determined in every experiment as a marker of the amount of mitochondria per chamber. Data are expressed on the basis of cell count (per million fibroblasts), of protein, or of citrate synthase activity. Cell growth conditions are optimized, and it is necessary to keep cultured cells from reaching confluency. Cultures in passages 3 to 10 show reproducible oxidative phosphorylation data. Based on the data from the 15 normal human skin fibroblast lines, we are evaluating the use of this approach to diagnose systemic mitochondrial disease and avoid issues associated with open skeletal muscle biopsy.
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Affiliation(s)
- Fang Ye
- Center for Mitochondrial Disease, Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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