1
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Lan T, Arastu S, Wang S, Lam J, Wang W, Bhatt V, Lopes EC, Hu Z, Sun M, Luo X, Ghergurovich JM, Li C, Su X, Rabinowitz JD, White E, Guo JY. G6PD Maintains Redox Homeostasis and Biosynthesis in LKB1-Deficient KRAS-Driven Lung Cancer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.06.561131. [PMID: 37873106 PMCID: PMC10592603 DOI: 10.1101/2023.10.06.561131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Cancer cells depend on nicotinamide adenine dinucleotide phosphate (NADPH) to combat oxidative stress and support reductive biosynthesis. One major NAPDH production route is the oxidative pentose phosphate pathway (committed step: glucose-6-phosphate dehydrogenase, G6PD). Alternatives exist and can compensate in some tumors. Here, using genetically-engineered lung cancer model, we show that ablation of G6PD significantly suppresses KrasG12D/+;Lkb1-/- (KL) but not KrasG12D/+;p53-/- (KP) lung tumorigenesis. In vivo isotope tracing and metabolomics revealed that G6PD ablation significantly impaired NADPH generation, redox balance and de novo lipogenesis in KL but not KP lung tumors. Mechanistically, in KL tumors, G6PD ablation caused p53 activation that suppressed tumor growth. As tumor progressed, G6PD-deficient KL tumors increased an alternative NADPH source, serine-driven one carbon metabolism, rendering associated tumor-derived cell lines sensitive to serine/glycine depletion. Thus, oncogenic driver mutations determine lung cancer dependence on G6PD, whose targeting is a potential therapeutic strategy for tumors harboring KRAS and LKB1 co-mutations.
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Affiliation(s)
- Taijin Lan
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, China
| | - Sara Arastu
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
| | - Samuel Wang
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
| | - Jarrick Lam
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
| | - Wenping Wang
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
| | - Vrushank Bhatt
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
| | - Eduardo Cararo Lopes
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Zhixian Hu
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
| | - Michael Sun
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
| | - Xuefei Luo
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
| | | | - Changlong Li
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu 610041, China
| | - Xiaoyang Su
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
- Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey 08901, USA
| | - Joshua D. Rabinowitz
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
- Ludwig Princeton Branch, Ludwig Institute for Cancer Research, Princeton University, Princeton, New Jersey 08540, USA
| | - Eileen White
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
- Ludwig Princeton Branch, Ludwig Institute for Cancer Research, Princeton University, Princeton, New Jersey 08540, USA
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Jessie Yanxiang Guo
- Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08901, USA
- Ludwig Princeton Branch, Ludwig Institute for Cancer Research, Princeton University, Princeton, New Jersey 08540, USA
- Department of Chemical Biology, Rutgers Ernest Mario School of Pharmacy, Piscataway, New Jersey 08854, USA
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2
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Anam AK, Cooke KM, Dratver MB, O'Bryan JV, Perley LE, Guller SM, Hwang JJ, Taylor HS, Goedeke L, Kliman HJ, Vatner DF, Flannery CA. Insulin increases placental triglyceride as a potential mechanism for fetal adiposity in maternal obesity. Mol Metab 2022; 64:101574. [PMID: 35970449 PMCID: PMC9440306 DOI: 10.1016/j.molmet.2022.101574] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 07/27/2022] [Accepted: 08/08/2022] [Indexed: 01/07/2023] Open
Abstract
OBJECTIVE Maternal obesity increases the incidence of excess adiposity in newborns, resulting in lifelong diabetes risk. Elevated intrauterine fetal adiposity has been attributed to maternal hyperglycemia; however, this hypothesis does not account for the increased adiposity seen in newborns of mothers with obesity who have euglycemia. We aimed to explore the placental response to maternal hyperinsulinemia and the effect of insulin-like growth factor 2 (IGF-2) in promoting fetal adiposity by increasing storage and availability of nutrients to the fetus. METHODS We used placental villous explants and isolated trophoblasts from normal weight and obese women to assess the effect of insulin and IGF-2 on triglyceride content and insulin receptor signaling. Stable isotope tracer methods were used ex vivo to determine effect of hormone treatment on de novo lipogenesis (DNL), fatty acid uptake, fatty acid oxidation, and esterification in the placenta. RESULTS Here we show that placentae from euglycemic women with normal weight and obesity both have abundant insulin receptor. Placental depth and triglyceride were greater in women with obesity compared with normal weight women. In syncytialized placental trophoblasts and villous explants, insulin and IGF-2 activate insulin receptor, induce expression of lipogenic transcription factor SREBP-1 (sterol regulatory element-binding protein 1), and stimulate triglyceride accumulation. We demonstrate elevated triglyceride is attributable to increased esterification of fatty acids, without contribution from DNL and without an acceleration of fatty acid uptake. CONCLUSIONS Our work reveals that obesity-driven aberrations in maternal metabolism, such as hyperinsulinemia, alter placental metabolism in euglycemic conditions, and may explain the higher prevalence of excess adiposity in the newborns of obese women.
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Affiliation(s)
- Anika K Anam
- Section of Endocrinology, Department of Internal Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Katherine M Cooke
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Milana Bochkur Dratver
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Jane V O'Bryan
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Lauren E Perley
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Seth M Guller
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Janice J Hwang
- Section of Endocrinology, Department of Internal Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Hugh S Taylor
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Leigh Goedeke
- Section of Endocrinology, Department of Internal Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Harvey J Kliman
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Daniel F Vatner
- Section of Endocrinology, Department of Internal Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Clare A Flannery
- Section of Endocrinology, Department of Internal Medicine, Yale School of Medicine, New Haven, CT, USA; Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA.
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3
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Belew GD, Jones JG. De novo lipogenesis in non-alcoholic fatty liver disease: Quantification with stable isotope tracers. Eur J Clin Invest 2022; 52:e13733. [PMID: 34927251 DOI: 10.1111/eci.13733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/11/2021] [Accepted: 12/13/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is characterized as an abnormal accumulation of triglyceride in hepatocytes. Hepatic de novo lipogenesis may play an important role in the accumulation of lipids in the liver during NAFLD. Due to the importance of lipid biosynthetic fluxes in NAFLD and T2D, tracer methodologies have been developed for their study and quantification. Here, we address novel approaches to measure and quantify DNL using stable isotope tracers. Deuterated water is a widely used tracer for quantifying DNL rates in both animal models and humans. Enrichment of lipid hydrogens from 2 H2O can be resolved and quantified by 2 H NMR and MS spectroscopy of isolated lipids. NMR provides a much higher level of positional enrichment information compared with MS which yields a more detailed picture of lipid biosynthetic. It can also be used to quantify low levels of lipid 13 C enrichment from a second tracer such as [U-13 C]sugar with minimal interference of one tracer with the other. CONCLUSIONS Despite the clear association between elevated DNL activity and increased hepatic triglyceride levels, implementation of non-destructive and novel methods to quantify DNL and its contribution to NAFLD are also of huge interest.
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Affiliation(s)
- Getachew Debas Belew
- Metabolism, Aging and Disease, Center for Neurosciences and Cell Biology, University of Coimbra, Cantanhede, Portugal
| | - John G Jones
- Metabolism, Aging and Disease, Center for Neurosciences and Cell Biology, University of Coimbra, Cantanhede, Portugal
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4
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Miura A, Ikeda A, Abe M, Seo K, Watanabe T, Ozaki-Masuzawa Y, Hosono T, Seki T. Diallyl Trisulfide Prevents Obesity and Decreases miRNA-335 Expression in Adipose Tissue in a Diet-Induced Obesity Rat Model. Mol Nutr Food Res 2021; 65:e2001199. [PMID: 34014027 DOI: 10.1002/mnfr.202001199] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 04/19/2021] [Indexed: 01/03/2023]
Abstract
SCOPE Diallyl trisulfide (DATS), an organosulfur compound generates in crushed garlic, has various beneficial health effects. A growing body of evidence indicates that miRNAs are involved in the pathology of lifestyle diseases including obesity. The anti-obesogenic effect of garlic is previously reported; however, the effects of DATS on obesity, and the relationship between garlic compounds and the involvement of miRNA remains unclear. Here, the anti-obesogenic activity of DATS and the potential role of miRNA in a diet-induced obesity rat model are investigated. METHODS AND RESULTS Oral administration of DATS suppressed body and white adipose tissue (WAT) weight gain in rats fed a high-fat diet compared with vehicle-administered rats. DATS lowered the plasma and liver triglyceride levels in obese rats, and decreased lipogenic mRNA levels including those of Srebp1c, Fasn, and Scd1 in the liver. DATS also suppressed de novo lipogenesis in the liver. Transcriptomic analyses of miRNA and mRNA in the epididymal WAT of obese rats using microarrays revealed that DATS decreased miRNA-335 expression and normalized the obesity-related mRNA transcriptomic signatures in epididymal WAT. CONCLUSION The potent anti-obesogenic effects of DATS and its possible mechanism of action was clearly demonstrated in this study.
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Affiliation(s)
- Atsushi Miura
- General Research Institute, Nihon University College of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
| | - Ayana Ikeda
- Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
| | - Marina Abe
- Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
| | - Kiki Seo
- Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
| | - Takahiro Watanabe
- Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
| | - Yori Ozaki-Masuzawa
- Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
| | - Takashi Hosono
- Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
- Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
| | - Taiichiro Seki
- General Research Institute, Nihon University College of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
- Department of Applied Life Sciences, Nihon University Graduate School of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
- Department of Chemistry and Life Science, Nihon University College of Bioresource Sciences, Fujisawa, Kanagawa, 252-0880, Japan
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5
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Scott DA. Analysis of Melanoma Cell Glutamine Metabolism by Stable Isotope Tracing and Gas Chromatography-Mass Spectrometry. Methods Mol Biol 2021; 2265:91-110. [PMID: 33704708 DOI: 10.1007/978-1-0716-1205-7_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Glutamine is a major substrate for biosynthesis. It contributes to multiple pathways required for cell proliferation, supports antioxidant defense via glutathione synthesis, and sustains the tricarboxylic acid (TCA) cycle through anaplerosis. Glutamine-fueled anaplerosis and related biosynthesis can be studied in detail in melanoma using stable isotope (13C) labeling followed by gas chromatography-mass spectrometry (GC-MS) analysis of metabolite amounts and labeling. Detailed protocols for the assay of polar metabolites (including amino acids, TCA cycle, and glycolysis metabolites) and fatty acids by these methods following cell treatment with 13C-glutamine or 13C-glucose are presented.
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Affiliation(s)
- David A Scott
- Cancer Metabolism Core, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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6
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Paluchova V, Oseeva M, Brezinova M, Cajka T, Bardova K, Adamcova K, Zacek P, Brejchova K, Balas L, Chodounska H, Kudova E, Schreiber R, Zechner R, Durand T, Rossmeisl M, Abumrad NA, Kopecky J, Kuda O. Lipokine 5-PAHSA Is Regulated by Adipose Triglyceride Lipase and Primes Adipocytes for De Novo Lipogenesis in Mice. Diabetes 2020; 69:300-312. [PMID: 31806624 PMCID: PMC7118252 DOI: 10.2337/db19-0494] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 11/30/2019] [Indexed: 12/18/2022]
Abstract
Branched esters of palmitic acid and hydroxystearic acid (PAHSA) are anti-inflammatory and antidiabetic lipokines that connect glucose and lipid metabolism. We aimed to characterize involvement of the 5-PAHSA regioisomer in the adaptive metabolic response of white adipose tissue (WAT) to cold exposure (CE) in mice, exploring the cross talk between glucose utilization and lipid metabolism. CE promoted local production of 5- and 9-PAHSAs in WAT. Metabolic labeling of de novo lipogenesis (DNL) using 2H2O revealed that 5-PAHSA potentiated the effects of CE and stimulated triacylglycerol (TAG)/fatty acid (FA) cycling in WAT through impacting lipogenesis and lipolysis. Adipocyte lipolytic products were altered by 5-PAHSA through selective FA re-esterification. The impaired lipolysis in global adipose triglyceride lipase (ATGL) knockout mice reduced free PAHSA levels and uncovered a metabolite reservoir of TAG-bound PAHSAs (TAG estolides) in WAT. Utilization of 13C isotope tracers and dynamic metabolomics documented that 5-PAHSA primes adipocytes for glucose metabolism in a different way from insulin, promoting DNL and impeding TAG synthesis. In summary, our data reveal new cellular and physiological mechanisms underlying the beneficial effects of 5-PAHSA and its relation to insulin action in adipocytes and independently confirm a PAHSA metabolite reservoir linked to ATGL-mediated lipolysis.
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Affiliation(s)
- Veronika Paluchova
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Marina Oseeva
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Marie Brezinova
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Tomas Cajka
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Kristina Bardova
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Katerina Adamcova
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Petr Zacek
- Proteomics Core Facility, Faculty of Science, Charles University, Division BIOCEV, Vestec, Czech Republic
| | - Kristyna Brejchova
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Laurence Balas
- Institut des Biomolécules Max Mousseron, UMR 5247, CNRS, Université Montpellier, and Faculté de Pharmacie, ENSCM, Montpellier, France
| | - Hana Chodounska
- Neurosteroids, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Eva Kudova
- Neurosteroids, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Thierry Durand
- Institut des Biomolécules Max Mousseron, UMR 5247, CNRS, Université Montpellier, and Faculté de Pharmacie, ENSCM, Montpellier, France
| | - Martin Rossmeisl
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Nada A Abumrad
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Jan Kopecky
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ondrej Kuda
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
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7
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Lord SR, Collins JM, Cheng WC, Haider S, Wigfield S, Gaude E, Fielding BA, Pinnick KE, Harjes U, Segaran A, Jha P, Hoefler G, Pollak MN, Thompson AM, Roy PG, English R, Adams RF, Frezza C, Buffa FM, Karpe F, Harris AL. Transcriptomic analysis of human primary breast cancer identifies fatty acid oxidation as a target for metformin. Br J Cancer 2020; 122:258-265. [PMID: 31819193 PMCID: PMC6986920 DOI: 10.1038/s41416-019-0665-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 11/12/2019] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Epidemiological studies suggest that metformin may reduce the incidence of cancer in patients with diabetes and multiple late phase clinical trials assessing the potential of repurposing this drug are underway. Transcriptomic profiling of tumour samples is an excellent tool to understand drug bioactivity, identify candidate biomarkers and assess for mechanisms of resistance to therapy. METHODS Thirty-six patients with untreated primary breast cancer were recruited to a window study and transcriptomic profiling of tumour samples carried out before and after metformin treatment. RESULTS Multiple genes that regulate fatty acid oxidation were upregulated at the transcriptomic level and there was a differential change in expression between two previously identified cohorts of patients with distinct metabolic responses. Increase in expression of a mitochondrial fatty oxidation gene composite signature correlated with change in a proliferation gene signature. In vitro assays showed that, in contrast to previous studies in models of normal cells, metformin reduces fatty acid oxidation with a subsequent accumulation of intracellular triglyceride, independent of AMPK activation. CONCLUSIONS We propose that metformin at clinical doses targets fatty acid oxidation in cancer cells with implications for patient selection and drug combinations. CLINICAL TRIAL REGISTRATION NCT01266486.
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Affiliation(s)
- Simon R Lord
- Department of Oncology, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK.
- Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS, UK.
- NIHR Oxford Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
| | - Jennifer M Collins
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Wei-Chen Cheng
- Department of Oncology, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Syed Haider
- The Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London, SW3 6JB, UK
| | - Simon Wigfield
- Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS, UK
| | - Edoardo Gaude
- MRC Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Cambridge Biomedical Campus, Cambridge, CB2 0XZ, UK
| | - Barbara A Fielding
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, GU2 7WG, UK
| | - Katherine E Pinnick
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Ulrike Harjes
- Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS, UK
| | - Ashvina Segaran
- Department of Oncology, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Pooja Jha
- Institut für Pathologie, Medizinische Universität Graz, Auenbruggerplatz 25, 8036, Graz, Austria
| | - Gerald Hoefler
- Institut für Pathologie, Medizinische Universität Graz, Auenbruggerplatz 25, 8036, Graz, Austria
| | - Michael N Pollak
- Department of Oncology, McGill University, Montreal, QC, H3T 1E2, Canada
| | - Alastair M Thompson
- Division of Surgical Oncology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Pankaj G Roy
- Breast Surgery Unit, Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Ruth English
- Oxford Breast Imaging Centre, Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Rosie F Adams
- Oxford Breast Imaging Centre, Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Christian Frezza
- MRC Cancer Unit, University of Cambridge, Hutchison/MRC Research Centre, Cambridge Biomedical Campus, Cambridge, CB2 0XZ, UK
| | - Francesca M Buffa
- Department of Oncology, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Fredrik Karpe
- NIHR Oxford Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
| | - Adrian L Harris
- Department of Oncology, University of Oxford, Churchill Hospital, Oxford, OX3 7LE, UK
- Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS, UK
- NIHR Oxford Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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8
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Argus JP, Wilks MQ, Zhou QD, Hsieh WY, Khialeeva E, Hoi XP, Bui V, Xu S, Yu AK, Wang ES, Herschman HR, Williams KJ, Bensinger SJ. Development and Application of FASA, a Model for Quantifying Fatty Acid Metabolism Using Stable Isotope Labeling. Cell Rep 2019; 25:2919-2934.e8. [PMID: 30517876 PMCID: PMC6432944 DOI: 10.1016/j.celrep.2018.11.041] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 07/23/2018] [Accepted: 11/09/2018] [Indexed: 12/20/2022] Open
Abstract
It is well understood that fatty acids can be synthesized, imported, and modified to meet requisite demands in cells. However, following the movement of fatty acids through the multiplicity of these metabolic steps has remained difficult. To better address this problem, we developed Fatty Acid Source Analysis (FASA), a model that defines the contribution of synthesis, import, and elongation pathways to fatty acid homeostasis in saturated, monounsaturated, and polyunsaturated fatty acid pools. Application of FASA demonstrated that elongation can be a major contributor to cellular fatty acid content and showed that distinct pro-inflammatory stimuli (e.g., Toll-like receptors 2, 3, or 4) specifically reprogram homeostasis of fatty acids by differential utilization of synthetic and elongation pathways in macrophages. In sum, this modeling approach significantly advances our ability to interrogate cellular fatty acid metabolism and provides insight into how cells dynamically reshape their lipidomes in response to metabolic or inflammatory signals. Argus et al. developed Fatty Acid Source Analysis (FASA), a model that quantifies cellular fatty acid synthesis, elongation, and import. FASA is used to demonstrate that elongation can be a major contributor to cellular fatty acid content and that different stimuli reprogram macrophage fatty acid elongation pathways in distinct ways.
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Affiliation(s)
- Joseph P Argus
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Moses Q Wilks
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 149, 13(th) Street, Charlestown, MA 02129, USA
| | - Quan D Zhou
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA; Department of Surgical Oncology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China
| | - Wei Yuan Hsieh
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Elvira Khialeeva
- Molecular Biology Institute, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Xen Ping Hoi
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Viet Bui
- Division of Rheumatology, David Geffen School of Medicine, University of California, Los Angeles, 1000 Veteran Avenue, Los Angeles, CA 90095, USA
| | - Shili Xu
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Amy K Yu
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Eric S Wang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Harvey R Herschman
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Kevin J Williams
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Steven J Bensinger
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, 615 Charles E. Young Drive East, Los Angeles, CA 90095, USA.
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9
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Ilchenko S, Haddad A, Sadana P, Recchia FA, Sadygov RG, Kasumov T. Calculation of the Protein Turnover Rate Using the Number of Incorporated 2H Atoms and Proteomics Analysis of a Single Labeled Sample. Anal Chem 2019; 91:14340-14351. [PMID: 31638786 DOI: 10.1021/acs.analchem.9b02757] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Rate constant estimation with heavy water requires a long-term experiment with data collection at multiple time points (3-4 weeks for mitochondrial proteome dynamics in mice and much longer in other species). When tissue proteins are analyzed, this approach requires euthanizing animals at each time point or multiple tissue biopsies in humans. Although short-term protocols are available, they require knowledge of the maximum number of isotope labels (N) and accurate quantification of observed 2H-enrichment in the peptide. The high-resolution accurate mass spectrometers used for proteome dynamics studies are characterized by a systematic spectral error that compromises these measurements. To circumvent these issues, we developed a simple algorithm for the rate constant calculation based on a single labeled sample and comparable unlabeled (time 0) sample. The algorithm determines N for all proteogenic amino acids from a long-term experiment to calculate the predicted plateau 2H-labeling of peptides for a short-term protocol and estimates the rate constant based on the measured baseline and the predicted plateau 2H-labeling of peptides. The method was validated based on the rate constant estimation in a long-term experiment in mice and dogs. The improved 2 time-point method enables the rate constant calculation with less than 10% relative error compared to the bench-marked multi-point method in mice and dogs and allows us to detect diet-induced subtle changes in ApoAI turnover in mice. In conclusion, we have developed and validated a new algorithm for protein rate constant calculation based on 2-time point measurements that could also be applied to other biomolecules.
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Affiliation(s)
- Serguei Ilchenko
- Northeast Ohio Medical University , Rootstown , Ohio 44272 , United States
| | - Andrew Haddad
- Northeast Ohio Medical University , Rootstown , Ohio 44272 , United States
| | - Prabodh Sadana
- Northeast Ohio Medical University , Rootstown , Ohio 44272 , United States
| | - Fabio A Recchia
- Institute of Life Sciences , Scuola Superiore Sant'Anna, Pisa, Fondazione Gabriele Monasterio , 56100 Pisa , Italy.,Cardiovascular Research Center , Lewis Katz School of Medicine at Temple University , Philadelphia , Pennsylvania 19140 , United States
| | - Rovshan G Sadygov
- University of Texas Medical Branch , Galveston , Texas 77555 , United States
| | - Takhar Kasumov
- Northeast Ohio Medical University , Rootstown , Ohio 44272 , United States
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10
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Belew GD, Silva J, Rito J, Tavares L, Viegas I, Teixeira J, Oliveira PJ, Macedo MP, Jones JG. Transfer of glucose hydrogens via acetyl-CoA, malonyl-CoA, and NADPH to fatty acids during de novo lipogenesis. J Lipid Res 2019; 60:2050-2056. [PMID: 31575642 DOI: 10.1194/jlr.ra119000354] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/30/2019] [Indexed: 01/05/2023] Open
Abstract
Deuterated water (2H2O) is widely used for measuring de novo lipogenesis (DNL). 2H is incorporated into fatty acids via exchange between body water and the hydrogens of acetyl-CoA, malonyl-CoA, and NADPH. Previous studies concluded that these exchanges are incomplete; therefore, fatty acid 2H enrichment requires correcting. In mice, we measured the 2H enrichment of fatty acid positions 2 and 3 and methyl hydrogens from [U-2H7]glucose to determine 2H transfer from glucose to fatty acid via malonyl-CoA, NADPH, and acetyl-CoA, respectively. Positional fatty acid 2H enrichments were compared with 13C enrichment of the same sites from an equivalent amount of [U-13C6]glucose provided alongside the [U-2H7]glucose tracer. Transfer of glucose 2H to fatty acid position 2 and methyl sites was low (2H enrichment of 0.06 ± 0.01 and 0.14 ± 0.01 relative to 13C) indicating extensive exchange at both malonyl- and acetyl-CoA, respectively. Transfer of glucose 2H into fatty acid position 3 was more extensive (0.46 ± 0.04 relative to 13C, P < 10-5 vs. position 2), indicating a more limited exchange of those glucose hydrogens that were transferred via NADPH. However, mice provided with [U-13C6]glucose and 2H2O had equivalent 2H enrichments of fatty acid positions 2 and 3, suggesting that in this setting, NADPH and body water 2H had exchanged extensively. This is explained by contributions of substrates other than exogenous glucose to DNL coupled with their extensive 2H enrichment from 2H2O prior to DNL. Under such conditions, 2H enrichment of fatty acids from 2H2O does not need correction.
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Affiliation(s)
- Getachew Debas Belew
- Center for Neurosciences and Cell Biology, University of Coimbra-Biotech University of Coimbra, Coimbra, Portugal
| | - Joao Silva
- Center for Neurosciences and Cell Biology, University of Coimbra-Biotech University of Coimbra, Coimbra, Portugal
| | - Joao Rito
- Center for Neurosciences and Cell Biology, University of Coimbra-Biotech University of Coimbra, Coimbra, Portugal
| | - Ludgero Tavares
- Center for Neurosciences and Cell Biology, University of Coimbra-Biotech University of Coimbra, Coimbra, Portugal
| | - Ivan Viegas
- Center for Neurosciences and Cell Biology, University of Coimbra-Biotech University of Coimbra, Coimbra, Portugal.,Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Jose Teixeira
- Center for Neurosciences and Cell Biology, University of Coimbra-Biotech University of Coimbra, Coimbra, Portugal
| | - Paulo J Oliveira
- Center for Neurosciences and Cell Biology, University of Coimbra-Biotech University of Coimbra, Coimbra, Portugal
| | - Maria Paula Macedo
- Chronic Diseases Research Center, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal.,Portuguese Diabetes Association, Lisbon, Portugal.,Department of Medical Sciences, Universidade Aveiro, Aveiro, Portugal
| | - John G Jones
- Center for Neurosciences and Cell Biology, University of Coimbra-Biotech University of Coimbra, Coimbra, Portugal .,Portuguese Diabetes Association, Lisbon, Portugal
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11
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Krois CR, Vuckovic MG, Huang P, Zaversnik C, Liu CS, Gibson CE, Wheeler MR, Obrochta KM, Min JH, Herber CB, Thompson AC, Shah ID, Gordon SP, Hellerstein MK, Napoli JL. RDH1 suppresses adiposity by promoting brown adipose adaptation to fasting and re-feeding. Cell Mol Life Sci 2019; 76:2425-2447. [PMID: 30788515 PMCID: PMC6531335 DOI: 10.1007/s00018-019-03046-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 02/07/2019] [Accepted: 02/11/2019] [Indexed: 12/26/2022]
Abstract
RDH1 is one of the several enzymes that catalyze the first of the two reactions to convert retinol into all-trans-retinoic acid (atRA). Here, we show that Rdh1-null mice fed a low-fat diet gain more weight as adiposity (17% males, 13% females) than wild-type mice by 20 weeks old, despite neither consuming more calories nor decreasing activity. Glucose intolerance and insulin resistance develop following increased adiposity. Despite the increase in white fat pads, epididymal white adipose does not express Rdh1, nor does muscle. Brown adipose tissue (BAT) and liver express Rdh1 at relatively high levels compared to other tissues. Rdh1 ablation lowered body temperatures during ambient conditions. Given the decreased body temperature, we focused on BAT. A lack of differences in BAT adipogenic gene expression between Rdh1-null mice and wild-type mice, including Pparg, Prdm16, Zfp516 and Zfp521, indicated that the phenotype was not driven by brown adipose hyperplasia. Rather, Rdh1 ablation eliminated the increase in BAT atRA that occurs after re-feeding. This disruption of atRA homeostasis increased fatty acid uptake, but attenuated lipolysis in primary brown adipocytes, resulting in increased lipid content and larger lipid droplets. Rdh1 ablation also decreased mitochondrial proteins, including CYCS and UCP1, the mitochondria oxygen consumption rate, and disrupted the mitochondria membrane potential, further reflecting impaired BAT function, resulting in both BAT and white adipose hypertrophy. RNAseq revealed dysregulation of 424 BAT genes in null mice, which segregated predominantly into differences after fasting vs after re-feeding. Exceptions were Rbp4 and Gbp2b, which increased during both dietary conditions. Rbp4 encodes the serum retinol-binding protein-an insulin desensitizer. Gbp2b encodes a GTPase. Because Gbp2b increased several hundred-fold, we overexpressed it in brown adipocytes. This caused a shift to larger lipid droplets, suggesting that GBP2b affects signaling downstream of the β-adrenergic receptor during basal thermogenesis. Thus, Rdh1-generated atRA in BAT regulates multiple genes that promote BAT adaptation to whole-body energy status, such as fasting and re-feeding. These gene expression changes promote optimum mitochondria function and thermogenesis, limiting adiposity. Attenuation of adiposity and insulin resistance suggests that RDH1 mitigates metabolic syndrome.
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Affiliation(s)
- Charles R Krois
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Department of Chemistry and Geology, Minnesota State University, 241 Ford Hall, Mankato, MN, 56001, USA
| | - Marta G Vuckovic
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
| | - Priscilla Huang
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Arizona College of Osteopathic Medicine, Midwestern University, 19555 North 59th Avenue, Glendale, AZ, 85308, USA
| | - Claire Zaversnik
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- AgroSup Dijon, 26 Bd Petitjean, 21000, Dijon, France
| | - Conan S Liu
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Sidney Kimmel Medical College, 1025 Walnut Street, Philadelphia, PA, 19104, USA
| | - Candice E Gibson
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
| | - Madelyn R Wheeler
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- UC Davis School of Medicine, 4102 Sherman Way, Sacramento, CA, 95817, USA
| | - Kristin M Obrochta
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Biomarin Pharmaceutical Inc., 105 Digital Drive, Novato, CA, 94949, USA
| | - Jin H Min
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Nova Southeastern University, 3301 College Avenue, Fort Lauderdale, FL, 33314, USA
| | - Candice B Herber
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- University of California, San Francisco, Rock Hall 281, 1550 4th Street, San Francisco, CA, 94158, USA
| | - Airlia C Thompson
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Stanford University, Lorry Lokey Building Room 164, 337 Campus Drive, Stanford, CA, 94305-5020, USA
| | - Ishan D Shah
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Keck School of Medicine, University of Southern California, 1975 Zonal Avenue, Keith Administration (KAM) 100, Los Angeles, CA, 90089-9020, USA
| | - Sean P Gordon
- DOE Joint Genome Institute, 2800 Mitchell Dr # 100, Walnut Creek, CA, 94598, USA
| | - Marc K Hellerstein
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
| | - Joseph L Napoli
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA.
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12
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Morrison DJ, Kowalski GM, Bruce CR, Wadley GD. Modest changes to glycemic regulation are sufficient to maintain glucose fluxes in healthy young men following overfeeding with a habitual macronutrient composition. Am J Physiol Endocrinol Metab 2019; 316:E1061-E1070. [PMID: 30964705 DOI: 10.1152/ajpendo.00500.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Currently, it is unclear whether short-term overfeeding in healthy people significantly affects postprandial glucose regulation, as most human overfeeding studies have utilized induced experimental conditions such as the euglycemic-hyperinsulinemic clamp technique to assess glucoregulation. The aim of this study was to quantify glucose fluxes [rates of meal glucose appearance (Ra), disposal (Rd), and endogenous glucose production (EGP)] in response to 5 and 28 days of overfeeding (+45% energy) while maintaining habitual macronutrient composition (31.0 ± 1.9% fat, 48.6 ± 2.2% carbohydrate, 16.7 ± 1.4% protein) in healthy, lean young men. Meal tolerance testing was combined with the triple-stable isotope glucose tracer approach. Visceral adipose volume increased by ~15% with 5 days of overfeeding, while there was no further change at 28 days. In contrast, body mass (+1.6 kg) and fat mass (+1.3 kg) were significantly increased only after 28 days of overfeeding. Fasting EGP, Rd, and insulin were increased at 5 but unchanged after 28 days. Postprandial glucose and insulin responses were unaltered by 5 days of overfeeding but were modestly increased after 28 days (P < 0.05). However, meal Ra and glucose Rd were significantly increased after both 5 and 28 days of overfeeding (P < 0.05). Despite this, overfeeding did not lead to alterations to postprandial EGP suppression. Thus, in contrast to findings from euglycemic-hyperinsulinemic clamp studies, chronic overfeeding did not affect the ability to suppress EGP or stimulate Rd under postprandial conditions. Rather, glucose flux was appropriately maintained following 28 days of overfeeding through modest increases in postprandial glycemia and insulinemia.
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Affiliation(s)
- Dale J Morrison
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University , Geelong , Australia
| | - Greg M Kowalski
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University , Geelong , Australia
| | - Clinton R Bruce
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University , Geelong , Australia
| | - Glenn D Wadley
- Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University , Geelong , Australia
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13
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Lane AN, Higashi RM, Fan TWM. NMR and MS-based Stable Isotope-Resolved Metabolomics and Applications in Cancer Metabolism. Trends Analyt Chem 2018; 120. [PMID: 32523238 DOI: 10.1016/j.trac.2018.11.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
There is considerable interest in defining metabolic reprogramming in human diseases, which is recognized as a hallmark of human cancer. Although radiotracers have a long history in specific metabolic studies, stable isotope-enriched precursors coupled with modern high resolution mass spectrometry and NMR spectroscopy have enabled systematic mapping of metabolic networks and fluxes in cells, tissues and living organisms including humans. These analytical platforms are high in information content, are complementary and cross-validating in terms of compound identification, quantification, and isotope labeling pattern analysis of a large number of metabolites simultaneously. Furthermore, new developments in chemoselective derivatization and in vivo spectroscopy enable tracking of labile/low abundance metabolites and metabolic kinetics in real-time. Here we review developments in Stable Isotope Resolved Metabolomics (SIRM) and recent applications in cancer metabolism using a wide variety of stable isotope tracers that probe both broad and specific aspects of cancer metabolism required for proliferation and survival.
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Affiliation(s)
- Andrew N Lane
- Center for Environmental and Systems Biochemistry, Dept. Toxicology and Cancer Biology, Markey Cancer Center, University of Kentucky, 789 S. Limestone St., Lexington, KY 40536 USA
| | - Richard M Higashi
- Center for Environmental and Systems Biochemistry, Dept. Toxicology and Cancer Biology, Markey Cancer Center, University of Kentucky, 789 S. Limestone St., Lexington, KY 40536 USA
| | - Teresa W-M Fan
- Center for Environmental and Systems Biochemistry, Dept. Toxicology and Cancer Biology, Markey Cancer Center, University of Kentucky, 789 S. Limestone St., Lexington, KY 40536 USA
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14
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Ang T, Kowalski GM, Bruce CR. Endogenous glucose production after sequential meals in humans: evidence for more prolonged suppression after ingestion of a second meal. Am J Physiol Endocrinol Metab 2018; 315:E904-E911. [PMID: 30106620 DOI: 10.1152/ajpendo.00233.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Single-meal studies have shown that carbohydrate ingestion causes rapid and persistent suppression of endogenous glucose production (EGP). However, little is known about the regulation of EGP under real-life eating patterns in which multiple carbohydrate-containing meals are consumed throughout the day. Therefore, we aimed to characterize the regulation of EGP in response to sequential meals, specifically during the breakfast-lunch transition. Nine healthy individuals (5 men, 4 women; 32 ± 2 yr; 25.0 ± 1.4 kg/m2) ingested two identical mixed meals, each containing 25 g of glucose, separated by 4 h, and EGP was determined by the variable infusion tracer-clamp approach. EGP was rapidly suppressed after both meals, with the pattern and magnitude of suppression being similar over the initial 75-min postmeal period. However, EGP suppression was more transient after breakfast compared with lunch, with EGP returning to basal rates 3 h after breakfast. In contrast, EGP remained in a suppressed state for the entire 4-h postlunch period. This occurred despite each meal eliciting similar plasma glucose and insulin responses. However, there was greater suppression of plasma glucagon levels after lunch, likely contributing to this response. These findings highlight the potential for distinct regulation of EGP with each meal of the day and suggest that EGP may be in a suppressed state for much of the day, since EGP did not return to basal rates even after a lunch meal containing a modest amount of carbohydrate.
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Affiliation(s)
- Teddy Ang
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University , Geelong , Australia
| | - Greg M Kowalski
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University , Geelong , Australia
| | - Clinton R Bruce
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University , Geelong , Australia
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15
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Sedgeman LR, Beysen C, Allen RM, Ramirez Solano MA, Turner SM, Vickers KC. Intestinal bile acid sequestration improves glucose control by stimulating hepatic miR-182-5p in type 2 diabetes. Am J Physiol Gastrointest Liver Physiol 2018; 315:G810-G823. [PMID: 30160993 PMCID: PMC6415711 DOI: 10.1152/ajpgi.00238.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Colesevelam is a bile acid sequestrant approved to treat both hyperlipidemia and type 2 diabetes, but the mechanism for its glucose-lowering effects is not fully understood. The aim of this study was to investigate the role of hepatic microRNAs (miRNAs) as regulators of metabolic disease and to investigate the link between the cholesterol and glucose-lowering effects of colesevelam. To quantify the impact of colesevelam treatment in rodent models of diabetes, metabolic studies were performed in Zucker diabetic fatty (ZDF) rats and db/db mice. Colesevelam treatments significantly decreased plasma glucose levels and increased glycolysis in the absence of changes to insulin levels in ZDF rats and db/db mice. High-throughput sequencing and real-time PCR were used to quantify hepatic miRNA and mRNA changes, and the cholesterol-sensitive miR-96/182/183 cluster was found to be significantly increased in livers from ZDF rats treated with colesevelam compared with vehicle controls. Inhibition of miR-182 in vivo attenuated colesevelam-mediated improvements to glycemic control in db/db mice. Hepatic expression of mediator complex subunit 1 (MED1), a nuclear receptor coactivator, was significantly decreased with colesevelam treatments in db/db mice, and MED1 was experimentally validated to be a direct target of miR-96/182/183 in humans and mice. In summary, these results support that colesevelam likely improves glycemic control through hepatic miR-182-5p, a mechanism that directly links cholesterol and glucose metabolism. NEW & NOTEWORTHY Colesevelam lowers systemic glucose levels in Zucker diabetic fatty rats and db/db mice and increases hepatic levels of the sterol response element binding protein 2-responsive microRNA cluster miR-96/182/183. Inhibition of miR-182 in vivo reverses the glucose-lowering effects of colesevelam in db/db mice. Mediator complex subunit 1 (MED1) is a novel, direct target of the miR-96/182/183 cluster in mice and humans.
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Affiliation(s)
- Leslie R. Sedgeman
- 1Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | | | - Ryan M. Allen
- 3Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | | | | | - Kasey C. Vickers
- 1Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee,3Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
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16
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Chen Y, Berejnaia O, Liu J, Wang SP, Daurio NA, Yin W, Mayoral R, Petrov A, Kasumov T, Zhang GF, Previs SF, Kelley DE, McLaren DG. Quantifying ceramide kinetics in vivo using stable isotope tracers and LC-MS/MS. Am J Physiol Endocrinol Metab 2018; 315:E416-E424. [PMID: 29509438 DOI: 10.1152/ajpendo.00457.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Numerous studies have implicated dyslipidemia as a key factor in mediating insulin resistance. Ceramides have received special attention since their levels are inversely associated with normal insulin signaling and positively associated with factors that are involved in cardiometabolic disease. Despite the growing literature surrounding ceramide biology, there are limited data regarding the activity of ceramide synthesis and turnover in vivo. Herein, we demonstrate the ability to measure ceramide kinetics by coupling the administration of [2H]water with LC-MS/MS analyses. As a "proof-of-concept" we determined the effect of a diet-induced alteration on ceramide flux; studies also examined the effect of myriocin (a known inhibitor of serine palmitoyltransferase, the first step in sphingosine biosynthesis). Our data suggest that one can estimate ceramide synthesis and draw conclusions regarding the source of fatty acids; we discuss caveats in regards to method development in this area.
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Affiliation(s)
- Ying Chen
- MRL, Merck & Co., Inc., Kenilworth, New Jersey
| | | | - Jinqi Liu
- MRL, Merck & Co., Inc., Kenilworth, New Jersey
| | | | | | - Wu Yin
- MRL, Merck & Co., Inc., Kenilworth, New Jersey
| | | | | | - Takhar Kasumov
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio
| | - Guo-Fang Zhang
- Division of Endocrinology, Metabolism and Nutrition, Duke Molecular Physiology Institute, and Department of Medicine, Duke University , Durham, North Carolina
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17
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Mast N, Bederman IR, Pikuleva IA. Retinal Cholesterol Content Is Reduced in Simvastatin-Treated Mice Due to Inhibited Local Biosynthesis Albeit Increased Uptake of Serum Cholesterol. Drug Metab Dispos 2018; 46:1528-1537. [PMID: 30115644 DOI: 10.1124/dmd.118.083345] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/14/2018] [Indexed: 12/18/2022] Open
Abstract
Statins, a class of cholesterol-lowering drugs, are currently being investigated for treatment of age-related macular degeneration, a retinal disease. Herein, retinal and serum concentrations of four statins (atorvastatin, simvastatin, pravastatin, and rosuvastatin) were evaluated after mice were given a single drug dose of 60 mg/kg body weight. All statins, except rosuvastatin, were detected in the retina: atorvastatin and pravastatin at 1.6 pmol and simvastatin at 4.1 pmol. Serum statin concentrations (pmol/ml) were 223 (simvastatin), 1401 (atorvastatin), 2792 (pravastatin), and 9050 (rosuvastatin). Simvastatin was then administered to mice daily for 6 weeks at 60 mg/kg body weight. Simvastatin treatment reduced serum cholesterol levels by 18% and retinal content of cholesterol and lathosterol (but not desmosterol) by 24% and 21%, respectively. The relative contributions of retinal cholesterol biosynthesis and retinal uptake of serum cholesterol to total retinal cholesterol input were changed as well. These contributions were 79% and 21%, respectively, in vehicle-treated mice and 69% and 31%, respectively, in simvastatin-treated mice. Thus, simvastatin treatment lowered retinal cholesterol because a compensatory upregulation of retinal uptake of serum cholesterol was not sufficient to overcome the effect of inhibited retinal biosynthesis. Simultaneously, simvastatin-treated mice had a 2.9-fold increase in retinal expression of Cd36, the major receptor clearing oxidized low-density lipoproteins from Bruch's membrane. Notably, simvastatin treatment essentially did not affect brain cholesterol homeostasis. Our results reveal the statin effect on the retinal and brain cholesterol input and are of value for future clinical investigations of statins as potential therapeutics for age-related macular degeneration.
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Affiliation(s)
- Natalia Mast
- Departments of Ophthalmology and Visual Sciences (N.M., I.A.P.) and Pediatrics (I.R.B.), Case Western Reserve University, Cleveland, Ohio
| | - Ilya R Bederman
- Departments of Ophthalmology and Visual Sciences (N.M., I.A.P.) and Pediatrics (I.R.B.), Case Western Reserve University, Cleveland, Ohio
| | - Irina A Pikuleva
- Departments of Ophthalmology and Visual Sciences (N.M., I.A.P.) and Pediatrics (I.R.B.), Case Western Reserve University, Cleveland, Ohio
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18
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Previs SF, Herath K, Nawrocki AR, Rodriguez CG, Slipetz D, Singh SB, Kang L, Bhat G, Roddy TP, Conarello S, Terebetski J, Erion MD, Kelley DE. Using [ 2H]water to quantify the contribution of de novo palmitate synthesis in plasma: enabling back-to-back studies. Am J Physiol Endocrinol Metab 2018; 315:E63-E71. [PMID: 29351479 DOI: 10.1152/ajpendo.00010.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An increased contribution of de novo lipogenesis (DNL) may play a role in cases of dyslipidemia and adipose accretion; this suggests that inhibition of fatty acid synthesis may affect clinical phenotypes. Since it is not clear whether modulation of one step in the lipogenic pathway is more important than another, the use of tracer methods can provide a deeper level of insight regarding the control of metabolic activity. Although [2H]water is generally considered a reliable tracer for quantifying DNL in vivo (it yields a homogenous and quantifiable precursor labeling), the relatively long half-life of body water is thought to limit the ability of performing repeat studies in the same subjects; this can create a bottleneck in the development and evaluation of novel therapeutics for inhibiting DNL. Herein, we demonstrate the ability to perform back-to-back studies of DNL using [2H]water. However, this work uncovered special circumstances that affect the data interpretation, i.e., it is possible to obtain seemingly negative values for DNL. Using a rodent model, we have identified a physiological mechanism that explains the data. We show that one can use [2H]water to test inhibitors of DNL by performing back-to-back studies in higher species [i.e., treat nonhuman primates with platensimycin, an inhibitor of fatty acid synthase]; studies also demonstrate the unsuitability of [13C]acetate.
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Affiliation(s)
- Stephen F Previs
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Kithsiri Herath
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Andrea R Nawrocki
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Carlos G Rodriguez
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Deborah Slipetz
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Sheo B Singh
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Ling Kang
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Gowri Bhat
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Thomas P Roddy
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Stacey Conarello
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Jenna Terebetski
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - Mark D Erion
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
| | - David E Kelley
- Merck Research Laboratories, Merck & Company, Incorporated, Kenilworth, New Jersey
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19
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Goh B, Kim J, Seo S, Kim TY. High-Throughput Measurement of Lipid Turnover Rates Using Partial Metabolic Heavy Water Labeling. Anal Chem 2018; 90:6509-6518. [DOI: 10.1021/acs.analchem.7b05428] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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20
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Morrison DJ, Kowalski GM, Grespan E, Mari A, Bruce CR, Wadley GD. Measurement of postprandial glucose fluxes in response to acute and chronic endurance exercise in healthy humans. Am J Physiol Endocrinol Metab 2018; 314:E503-E511. [PMID: 29351488 DOI: 10.1152/ajpendo.00316.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The effect of endurance exercise on enhancing insulin sensitivity and glucose flux has been well established with techniques such as the hyperinsulinemic clamp. Although informative, such techniques do not emulate the physiological postprandial state, and it remains unclear how exercise improves postprandial glycaemia. Accordingly, combining mixed-meal tolerance testing and the triple-stable isotope glucose tracer approach, glucose fluxes [rates of meal glucose appearance (Ra), disposal (Rd), and endogenous glucose production (EGP)] were determined following acute endurance exercise (1 h cycling; ~70% V̇o2max) and 4 wk of endurance training (cycling 5 days/wk). Training was associated with a modest increase in V̇o2max (~7%, P < 0.001). Postprandial glucose and insulin responses were reduced to the same extent following acute and chronic training. Interestingly, this was not accompanied by changes to rates of meal Ra, Rd, or degree of EGP suppression. Glucose clearance (Rd relative to prevailing glucose) was, however, enhanced with acute and chronic exercise. Furthermore, the duration of EGP suppression was shorter with acute and chronic exercise, with EGP returning toward fasting levels more rapidly than pretraining conditions. These findings suggest that endurance exercise influences the efficiency of the glucoregulatory system, where pretraining rates of glucose disposal and production were achieved at lower glucose and insulin levels. Notably, there was no influence of chronic training over and above that of a single exercise bout, providing further evidence that glucoregulatory benefits of endurance exercise are largely attributed to the residual effects of the last exercise bout.
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Affiliation(s)
- Dale J Morrison
- Deakin University, Geelong, Australia, Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Burwood, Australia
| | - Greg M Kowalski
- Deakin University, Geelong, Australia, Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Burwood, Australia
| | | | - Andrea Mari
- CNR Institute of Neuroscience , Padua , Italy
| | - Clinton R Bruce
- Deakin University, Geelong, Australia, Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Burwood, Australia
| | - Glenn D Wadley
- Deakin University, Geelong, Australia, Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Burwood, Australia
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21
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Zhang Z, Chen L, Liu L, Su X, Rabinowitz JD. Chemical Basis for Deuterium Labeling of Fat and NADPH. J Am Chem Soc 2017; 139:14368-14371. [PMID: 28911221 DOI: 10.1021/jacs.7b08012] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Much understanding of metabolism is based on monitoring chemical reactions in cells with isotope tracers. For this purpose, 13C is well suited due to its stable incorporation into biomolecules and minimal kinetic isotope effect. For redox reactions, deuterium tracing can provide additional information. To date, studies examining NADPH production with deuterated carbon sources have failed to account for roughly half of NADPH's redox active hydrogen. We show the missing hydrogen is the result of enzyme-catalyzed H-D exchange between water and NADPH. Though isolated NADPH does not undergo H-D exchange with water, such exchange is catalyzed by Flavin enzymes and occurs rapidly in cells. Correction for H-D exchange is required for accurate assessment of biological sources of NADPH's high energy electrons. Deuterated water (D2O) is frequently used to monitor fat synthesis in vivo, but the chemical pathway of the deuterons into fat remains unclear. We show D2O labels fatty acids primarily via NADPH. Knowledge of this route enables calculation, without any fitting parameters, of the mass isotopomer distributions of fatty acids from cells grown in D2O. Thus, knowledge of enzyme-catalyzed H-D exchange between water and NADPH enables accurate interpretation of deuterium tracing studies of redox cofactor and fatty acid metabolism.
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Affiliation(s)
- Zhaoyue Zhang
- Lewis-Sigler Institute for Integrative Genomics, Princeton University , Princeton, New Jersey 08544, United States.,Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Li Chen
- Lewis-Sigler Institute for Integrative Genomics, Princeton University , Princeton, New Jersey 08544, United States.,Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Ling Liu
- Lewis-Sigler Institute for Integrative Genomics, Princeton University , Princeton, New Jersey 08544, United States.,Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Xiaoyang Su
- Department of Medicine, Robert Wood Johnson Medical School, Rutgers University , New Brunswick, New Jersey 08544, United States
| | - Joshua D Rabinowitz
- Lewis-Sigler Institute for Integrative Genomics, Princeton University , Princeton, New Jersey 08544, United States.,Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
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22
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Analysis of Mammalian Cell Proliferation and Macromolecule Synthesis Using Deuterated Water and Gas Chromatography-Mass Spectrometry. Metabolites 2016; 6:metabo6040034. [PMID: 27754354 PMCID: PMC5192440 DOI: 10.3390/metabo6040034] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/10/2016] [Accepted: 10/10/2016] [Indexed: 11/16/2022] Open
Abstract
Deuterated water (²H₂O), a stable isotopic tracer, provides a convenient and reliable way to label multiple cellular biomass components (macromolecules), thus permitting the calculation of their synthesis rates. Here, we have combined ²H₂O labelling, GC-MS analysis and a novel cell fractionation method to extract multiple biomass components (DNA, protein and lipids) from the one biological sample, thus permitting the simultaneous measurement of DNA (cell proliferation), protein and lipid synthesis rates. We have used this approach to characterize the turnover rates and metabolism of a panel of mammalian cells in vitro (muscle C2C12 and colon cancer cell lines). Our data show that in actively-proliferating cells, biomass synthesis rates are strongly linked to the rate of cell division. Furthermore, in both proliferating and non-proliferating cells, it is the lipid pool that undergoes the most rapid turnover when compared to DNA and protein. Finally, our data in human colon cancer cell lines reveal a marked heterogeneity in the reliance on the de novo lipogenic pathway, with the cells being dependent on both 'self-made' and exogenously-derived fatty acid.
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23
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Srivastava A, Kowalski GM, Callahan DL, Meikle PJ, Creek DJ. Strategies for Extending Metabolomics Studies with Stable Isotope Labelling and Fluxomics. Metabolites 2016; 6:metabo6040032. [PMID: 27706078 PMCID: PMC5192438 DOI: 10.3390/metabo6040032] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/21/2016] [Accepted: 09/28/2016] [Indexed: 12/13/2022] Open
Abstract
This is a perspective from the peer session on stable isotope labelling and fluxomics at the Australian & New Zealand Metabolomics Conference (ANZMET) held from 30 March to 1 April 2016 at La Trobe University, Melbourne, Australia. This report summarizes the key points raised in the peer session which focused on the advantages of using stable isotopes in modern metabolomics and the challenges in conducting flux analyses. The session highlighted the utility of stable isotope labelling in generating reference standards for metabolite identification, absolute quantification, and in the measurement of the dynamic activity of metabolic pathways. The advantages and disadvantages of different approaches of fluxomics analyses including flux balance analysis, metabolic flux analysis and kinetic flux profiling were also discussed along with the use of stable isotope labelling in in vivo dynamic metabolomics. A number of crucial technical considerations for designing experiments and analyzing data with stable isotope labelling were discussed which included replication, instrumentation, methods of labelling, tracer dilution and data analysis. This report reflects the current viewpoint on the use of stable isotope labelling in metabolomics experiments, identifying it as a great tool with the potential to improve biological interpretation of metabolomics data in a number of ways.
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Affiliation(s)
- Anubhav Srivastava
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Melbourne, Victoria, Australia.
| | - Greg M Kowalski
- Institute for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood 3125, Victoria, Australia.
| | - Damien L Callahan
- Centre for Chemistry and Biotechnology, School of Life and Environmental Sciences, Deakin University, Burwood 3125, Victoria, Australia.
| | - Peter J Meikle
- Baker IDI Heart and Diabetes Institute, Melbourne 3004, Victoria, Australia.
| | - Darren J Creek
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Melbourne, Victoria, Australia.
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24
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Monnerie H, Romer M, Jensen BK, Millar JS, Jordan-Sciutto KL, Kim SF, Grinspan JB. Reduced sterol regulatory element-binding protein (SREBP) processing through site-1 protease (S1P) inhibition alters oligodendrocyte differentiation in vitro. J Neurochem 2016; 140:53-67. [PMID: 27385127 DOI: 10.1111/jnc.13721] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 05/24/2016] [Accepted: 06/28/2016] [Indexed: 01/09/2023]
Abstract
The formation of the myelin membrane of the oligodendrocyte in the CNS is a fundamental process requiring the coordinated synthesis of many different components. The myelin membrane is particularly rich in lipids, however, the regulation of this lipid synthesis is not understood. In other cell types, including Schwann cells, the myelin-forming cells of the PNS, lipid synthesis is tightly regulated by the sterol regulatory element-binding protein (SREBP) family of transcription factors, but this has not been previously shown in oligodendrocytes. We investigated SREBPs' role during oligodendrocyte differentiation in vitro. Both SREBP-1 and SREBP-2 were expressed in oligodendrocyte precursor cells and differentiating oligodendrocytes. Using the selective site-1 protease (S1P) inhibitor PF-429242, which inhibits the cleavage of SREBP precursor forms into mature forms, we found that preventing SREBP processing inhibited process growth and reduced the expression level of myelin basic protein, a major component of myelin. Further, process extension deficits could be rescued by the addition of exogenous cholesterol. Blocking SREBP processing reduced mRNA transcription and protein levels of SREBP target genes involved in both the fatty acid and the cholesterol synthetic pathways. Furthermore, de novo levels and total levels of cholesterol synthesis were greatly diminished when SREBP processing was inhibited. Together these results indicate that SREBPs are important regulators of oligodendrocyte maturation and that perturbation of their activity may affect myelin formation and integrity. Cover Image for this issue: doi: 10.1111/jnc.13781.
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Affiliation(s)
- Hubert Monnerie
- Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Micah Romer
- Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Brigid K Jensen
- Department of Neuroscience, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - John S Millar
- Institute of Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kelly L Jordan-Sciutto
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sangwon F Kim
- Department of Psychiatry, Center for Neurobiology and Behavior, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Judith B Grinspan
- Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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25
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Monnerie H, Romer M, Jensen BK, Millar JS, Jordan-Sciutto KL, Kim SF, Grinspan JB. Reduced sterol regulatory element-binding protein (SREBP) processing through site-1 protease (S1P) inhibition alters oligodendrocyte differentiation in vitro. J Neurochem 2016. [PMID: 27385127 DOI: 10.1111/jnc.13781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The formation of the myelin membrane of the oligodendrocyte in the CNS is a fundamental process requiring the coordinated synthesis of many different components. The myelin membrane is particularly rich in lipids, however, the regulation of this lipid synthesis is not understood. In other cell types, including Schwann cells, the myelin-forming cells of the PNS, lipid synthesis is tightly regulated by the sterol regulatory element-binding protein (SREBP) family of transcription factors, but this has not been previously shown in oligodendrocytes. We investigated SREBPs' role during oligodendrocyte differentiation in vitro. Both SREBP-1 and SREBP-2 were expressed in oligodendrocyte precursor cells and differentiating oligodendrocytes. Using the selective site-1 protease (S1P) inhibitor PF-429242, which inhibits the cleavage of SREBP precursor forms into mature forms, we found that preventing SREBP processing inhibited process growth and reduced the expression level of myelin basic protein, a major component of myelin. Further, process extension deficits could be rescued by the addition of exogenous cholesterol. Blocking SREBP processing reduced mRNA transcription and protein levels of SREBP target genes involved in both the fatty acid and the cholesterol synthetic pathways. Furthermore, de novo levels and total levels of cholesterol synthesis were greatly diminished when SREBP processing was inhibited. Together these results indicate that SREBPs are important regulators of oligodendrocyte maturation and that perturbation of their activity may affect myelin formation and integrity. Cover Image for this issue: doi: 10.1111/jnc.13781.
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Affiliation(s)
- Hubert Monnerie
- Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Micah Romer
- Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Brigid K Jensen
- Department of Neuroscience, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - John S Millar
- Institute of Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kelly L Jordan-Sciutto
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sangwon F Kim
- Department of Psychiatry, Center for Neurobiology and Behavior, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Judith B Grinspan
- Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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26
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Lin JB, Mast N, Bederman IR, Li Y, Brunengraber H, Björkhem I, Pikuleva IA. Cholesterol in mouse retina originates primarily from in situ de novo biosynthesis. J Lipid Res 2015; 57:258-64. [PMID: 26630912 DOI: 10.1194/jlr.m064469] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Indexed: 12/18/2022] Open
Abstract
The retina, a thin tissue in the back of the eye, has two apparent sources of cholesterol: in situ biosynthesis and cholesterol available from the systemic circulation. The quantitative contributions of these two cholesterol sources to the retinal cholesterol pool are unknown and have been determined in the present work. A new methodology was used. Mice were given separately deuterium-labeled drinking water and chow containing 0.3% deuterium-labeled cholesterol. In the retina, the rate of total cholesterol input was 21 μg of cholesterol/g retina • day, of which 15 μg of cholesterol/g retina • day was provided by local biosynthesis and 6 μg of cholesterol/g retina • day was uptaken from the systemic circulation. Thus, local cholesterol biosynthesis accounts for the majority (72%) of retinal cholesterol input. We also quantified cholesterol input to mouse brain, the organ sharing important similarities with the retina. The rate of total cerebral cholesterol input was 121 μg of cholesterol/g brain • day with local biosynthesis providing 97% of total cholesterol input. Our work addresses a long-standing question in eye research and adds new knowledge to the potential use of statins (drugs that inhibit cholesterol biosynthesis) as therapeutics for age-related macular degeneration, a common blinding disease.
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Affiliation(s)
- Joseph B Lin
- Department of Ophthalmology and Visual Sciences,Case Western Reserve University, Cleveland, OH 44106
| | - Natalia Mast
- Department of Ophthalmology and Visual Sciences,Case Western Reserve University, Cleveland, OH 44106
| | - Ilya R Bederman
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH 44106
| | - Yong Li
- Department of Ophthalmology and Visual Sciences,Case Western Reserve University, Cleveland, OH 44106
| | - Henri Brunengraber
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106
| | - Ingemar Björkhem
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska University Hospital, Karolinska Institute, Huddinge, Stockholm 141 86 Sweden
| | - Irina A Pikuleva
- Department of Ophthalmology and Visual Sciences,Case Western Reserve University, Cleveland, OH 44106
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27
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Mitsche MA, McDonald JG, Hobbs HH, Cohen JC. Flux analysis of cholesterol biosynthesis in vivo reveals multiple tissue and cell-type specific pathways. eLife 2015; 4:e07999. [PMID: 26114596 PMCID: PMC4501332 DOI: 10.7554/elife.07999] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 06/25/2015] [Indexed: 01/22/2023] Open
Abstract
Two parallel pathways produce cholesterol: the Bloch and Kandutsch-Russell pathways. Here we used stable isotope labeling and isotopomer analysis to trace sterol flux through the two pathways in mice. Surprisingly, no tissue used the canonical K–R pathway. Rather, a hybrid pathway was identified that we call the modified K–R (MK–R) pathway. Proportional flux through the Bloch pathway varied from 8% in preputial gland to 97% in testes, and the tissue-specificity observed in vivo was retained in cultured cells. The distribution of sterol isotopomers in plasma mirrored that of liver. Sterol depletion in cultured cells increased flux through the Bloch pathway, whereas overexpression of 24-dehydrocholesterol reductase (DHCR24) enhanced usage of the MK–R pathway. Thus, relative use of the Bloch and MK–R pathways is highly variable, tissue-specific, flux dependent, and epigenetically fixed. Maintenance of two interdigitated pathways permits production of diverse bioactive sterols that can be regulated independently of cholesterol. DOI:http://dx.doi.org/10.7554/eLife.07999.001 Cholesterol is important for animals, both as an essential component of the membrane that surrounds cells and as a building block to make hormones and other biologically important molecules. However, cells limit how much cholesterol they make because an excess of this fatty molecule can cause serious health problems, including heart disease and stroke. Cholesterol is made via a complex process that involves more than 30 different steps, which can be organized into two biochemical pathways (named the Bloch pathway and the Kandutsch–Russell pathway). The enzymes that carry out the steps in these pathways have been characterized in detail. Less is known about which of the two pathways is actually used in different cells and tissues, or how much cholesterol each pathway produces. This is partly because it is difficult to distinguish between the closely related intermediate molecules that are formed in each pathway. Mitsche et al. have now used mass spectrometry and isotope labeling techniques to analyze the relative contributions of the two cholesterol-making pathways in both cells grown in the laboratory and in mice. The experiments show that many cells use the Bloch pathway. However, no cells were found to use the Kandutsch–Russell pathway as it was originally described. Rather, some of the cells used a hybrid pathway where the production of cholesterol was started using the Bloch pathway and then after a certain number of steps, the process switched to using part of the Kandutsch–Russell pathway. Mitsche et al. referred to this mixed system as the ‘modified Kandutsch–Russell pathway’. Mitsche et al. next examined the flow of molecules through these two pathways in different tissues and observed that the Bloch pathway is exclusively used in the testes and adrenal glands, which produce high levels of cholesterol. In contrast, the skin and brain use the modified Kandutsch–Russell pathway. In some tissues, a fraction of the building blocks that can be used to make cholesterol were instead diverted to make other products. This suggests that animals have maintained the two pathways over the course of evolution to enable them to generate a variety of products, which can be used to carry out different biological processes. One challenge following this work will be to use the newly developed methods to analyze other complex biochemical pathways. DOI:http://dx.doi.org/10.7554/eLife.07999.002
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Affiliation(s)
- Matthew A Mitsche
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jeffrey G McDonald
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Helen H Hobbs
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jonathan C Cohen
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, United States
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28
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Robertson CL, Srivastava J, Siddiq A, Gredler R, Emdad L, Rajasekaran D, Akiel M, Shen XN, Corwin F, Sundaresan G, Zweit J, Croniger C, Gao X, Ghosh S, Hylemon PB, Subler MA, Windle JJ, Fisher PB, Sarkar D. Astrocyte Elevated Gene-1 (AEG-1) Regulates Lipid Homeostasis. J Biol Chem 2015; 290:18227-18236. [PMID: 26070567 DOI: 10.1074/jbc.m115.661801] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Indexed: 12/14/2022] Open
Abstract
Astrocyte elevated gene-1 (AEG-1), also known as MTDH (metadherin) or LYRIC, is an established oncogene. However, the physiological function of AEG-1 is not known. To address this question, we generated an AEG-1 knock-out mouse (AEG-1KO) and characterized it. Although AEG-1KO mice were viable and fertile, they were significantly leaner with prominently less body fat and lived significantly longer compared with wild type (WT). When fed a high fat and cholesterol diet (HFD), WT mice rapidly gained weight, whereas AEG-1KO mice did not gain weight at all. This phenotype of AEG-1KO mice is due to decreased fat absorption from the intestines, not because of decreased fat synthesis or increased fat consumption. AEG-1 interacts with retinoid X receptor (RXR) and inhibits RXR function. In enterocytes of AEG-1KO mice, we observed increased activity of RXR heterodimer partners, liver X receptor and peroxisome proliferator-activated receptor-α, key inhibitors of intestinal fat absorption. Inhibition of fat absorption in AEG-1KO mice was further augmented when fed an HFD providing ligands to liver X receptor and peroxisome proliferator-activated receptor-α. Our studies reveal a novel role of AEG-1 in regulating nuclear receptors controlling lipid metabolism. AEG-1 may significantly modulate the effects of HFD and thereby function as a unique determinant of obesity.
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Affiliation(s)
- Chadia L Robertson
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298; Departments of Biochemistry, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Jyoti Srivastava
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Ayesha Siddiq
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Rachel Gredler
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Luni Emdad
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Devaraja Rajasekaran
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Maaged Akiel
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Xue-Ning Shen
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Frank Corwin
- Departments of Radiology, Virginia Commonwealth University, Richmond, Virginia 23298
| | | | - Jamal Zweit
- Departments of Radiology, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Colleen Croniger
- Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106
| | - Xiaoli Gao
- Institutional Mass Spectrometry Laboratory, University of Texas Health Science Center, San Antonio, Texas 78229
| | - Shobha Ghosh
- Departments of Internal Medicine, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Philip B Hylemon
- Departments of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Mark A Subler
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Jolene J Windle
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298; Departments of VCU Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Paul B Fisher
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298; Departments of VCU Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23298; VCU Institute of Molecular Medicine, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Devanand Sarkar
- Departments of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298; Departments of VCU Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23298; VCU Institute of Molecular Medicine, Virginia Commonwealth University, Richmond, Virginia 23298.
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29
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Lee J, Walsh MC, Hoehn KL, James DE, Wherry EJ, Choi Y. Regulator of fatty acid metabolism, acetyl coenzyme a carboxylase 1, controls T cell immunity. THE JOURNAL OF IMMUNOLOGY 2014; 192:3190-9. [PMID: 24567531 DOI: 10.4049/jimmunol.1302985] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Fatty acids (FAs) are essential constituents of cell membranes, signaling molecules, and bioenergetic substrates. Because CD8(+) T cells undergo both functional and metabolic changes during activation and differentiation, dynamic changes in FA metabolism also occur. However, the contributions of de novo lipogenesis to acquisition and maintenance of CD8(+) T cell function are unclear. In this article, we demonstrate the role of FA synthesis in CD8(+) T cell immunity. T cell-specific deletion of acetyl coenzyme A carboxylase 1 (ACC1), an enzyme that catalyzes conversion of acetyl coenzyme A to malonyl coenzyme A, a carbon donor for long-chain FA synthesis, resulted in impaired peripheral persistence and homeostatic proliferation of CD8(+) T cells in naive mice. Loss of ACC1 did not compromise effector CD8(+) T cell differentiation upon listeria infection but did result in a severe defect in Ag-specific CD8(+) T cell accumulation because of increased death of proliferating cells. Furthermore, in vitro mitogenic stimulation demonstrated that defective blasting and survival of ACC1-deficient CD8(+) T cells could be rescued by provision of exogenous FA. These results suggest an essential role for ACC1-mediated de novo lipogenesis as a regulator of CD8(+) T cell expansion, and may provide insights for therapeutic targets for interventions in autoimmune diseases, cancer, and chronic infections.
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Affiliation(s)
- JangEun Lee
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
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30
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Chen CT, Domenichiello AF, Trépanier MO, Liu Z, Masoodi M, Bazinet RP. The low levels of eicosapentaenoic acid in rat brain phospholipids are maintained via multiple redundant mechanisms. J Lipid Res 2013; 54:2410-22. [PMID: 23836105 PMCID: PMC3735939 DOI: 10.1194/jlr.m038505] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/26/2013] [Indexed: 12/19/2022] Open
Abstract
Brain eicosapentaenoic acid (EPA) levels are 250- to 300-fold lower than docosahexaenoic acid (DHA), at least partly, because EPA is rapidly β-oxidized and lost from brain phospholipids. Therefore, we examined if β-oxidation was necessary for maintaining low EPA levels by inhibiting β-oxidation with methyl palmoxirate (MEP). Furthermore, because other metabolic differences between DHA and EPA may also contribute to their vastly different levels, this study aimed to quantify the incorporation and turnover of DHA and EPA into brain phospholipids. Fifteen-week-old rats were subjected to vehicle or MEP prior to a 5 min intravenous infusion of (14)C-palmitate, (14)C-DHA, or (14)C-EPA. MEP reduced the radioactivity of brain aqueous fractions for (14)C-palmitate-, (14)C-EPA-, and (14)C-DHA-infused rats by 74, 54, and 23%, respectively; while it increased the net rate of incorporation of plasma unesterified palmitate into choline glycerophospholipids and phosphatidylinositol and EPA into ethanolamine glycerophospholipids and phosphatidylserine. MEP also increased the synthesis of n-3 docosapentaenoic acid (n-3 DPA) from EPA. Moreover, the recycling of EPA into brain phospholipids was 154-fold lower than DHA. Therefore, the low levels of EPA in the brain are maintained by multiple redundant pathways including β-oxidation, decreased incorporation from plasma unesterified FA pool, elongation/desaturation to n-3 DPA, and lower recycling within brain phospholipids.
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Affiliation(s)
- Chuck T. Chen
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 3E2; and
| | - Anthony F. Domenichiello
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 3E2; and
| | - Marc-Olivier Trépanier
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 3E2; and
| | - Zhen Liu
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 3E2; and
| | - Mojgan Masoodi
- Nestlé Institute of Health Sciences SA, Campus EPFL, Quartier de l'innovation, bâtiment G, 1015 Lausanne, Switzerland
| | - Richard P. Bazinet
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 3E2; and
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31
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Laurent G, German NJ, Saha AK, de Boer VCJ, Davies M, Koves TR, Dephoure N, Fischer F, Boanca G, Vaitheesvaran B, Lovitch SB, Sharpe AH, Kurland IJ, Steegborn C, Gygi SP, Muoio DM, Ruderman NB, Haigis MC. SIRT4 coordinates the balance between lipid synthesis and catabolism by repressing malonyl CoA decarboxylase. Mol Cell 2013; 50:686-98. [PMID: 23746352 DOI: 10.1016/j.molcel.2013.05.012] [Citation(s) in RCA: 268] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 03/22/2013] [Accepted: 05/02/2013] [Indexed: 12/01/2022]
Abstract
Lipid metabolism is tightly controlled by the nutritional state of the organism. Nutrient-rich conditions increase lipogenesis, whereas nutrient deprivation promotes fat oxidation. In this study, we identify the mitochondrial sirtuin, SIRT4, as a regulator of lipid homeostasis. SIRT4 is active in nutrient-replete conditions to repress fatty acid oxidation while promoting lipid anabolism. SIRT4 deacetylates and inhibits malonyl CoA decarboxylase (MCD), an enzyme that produces acetyl CoA from malonyl CoA. Malonyl CoA provides the carbon skeleton for lipogenesis and also inhibits fat oxidation. Mice lacking SIRT4 display elevated MCD activity and decreased malonyl CoA in skeletal muscle and white adipose tissue. Consequently, SIRT4 KO mice display deregulated lipid metabolism, leading to increased exercise tolerance and protection against diet-induced obesity. In sum, this work elucidates SIRT4 as an important regulator of lipid homeostasis, identifies MCD as a SIRT4 target, and deepens our understanding of the malonyl CoA regulatory axis.
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Affiliation(s)
- Gaëlle Laurent
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
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32
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Kasumov T, Dabkowski ER, Shekar KC, Li L, Ribeiro RF, Walsh K, Previs SF, Sadygov RG, Willard B, Stanley WC. Assessment of cardiac proteome dynamics with heavy water: slower protein synthesis rates in interfibrillar than subsarcolemmal mitochondria. Am J Physiol Heart Circ Physiol 2013; 304:H1201-14. [PMID: 23457012 DOI: 10.1152/ajpheart.00933.2012] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Traditional proteomics provides static assessment of protein content, but not synthetic rates. Recently, proteome dynamics with heavy water ((2)H2O) was introduced, where (2)H labels amino acids that are incorporated into proteins, and the synthesis rate of individual proteins is calculated using mass isotopomer distribution analysis. We refine this approach with a novel algorithm and rigorous selection criteria that improve the accuracy and precision of the calculation of synthesis rates and use it to measure protein kinetics in spatially distinct cardiac mitochondrial subpopulations. Subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM) were isolated from adult rats, which were given (2)H2O in the drinking water for up to 60 days. Plasma (2)H2O and myocardial (2)H-enrichment of amino acids were stable throughout the experimental protocol. Multiple tryptic peptides were identified from 28 proteins in both SSM and IFM and showed a time-dependent increase in heavy mass isotopomers that was consistent within a given protein. Mitochondrial protein synthesis was relatively slow (average half-life of 30 days, 2.4% per day). Although the synthesis rates for individual proteins were correlated between IFM and SSM (R(2) = 0.84; P < 0.0001), values in IFM were 15% less than SSM (P < 0.001). In conclusion, administration of (2)H2O results in stable enrichment of the cardiac precursor amino acid pool, with the use of refined analytical and computational methods coupled with cell fractionation one can measure synthesis rates for cardiac proteins in subcellular compartments in vivo, and protein synthesis is slower in mitochondria located among the myofibrils than in the subsarcolemmal region.
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Affiliation(s)
- Takhar Kasumov
- Department of Gastroenterology and Hepatology, Cleveland Clinic, Cleveland, Ohio 44195, USA.
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33
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Garg M, Thamotharan M, Dai Y, Lagishetty V, Matveyenko AV, Lee WNP, Devaskar SU. Glucose intolerance and lipid metabolic adaptations in response to intrauterine and postnatal calorie restriction in male adult rats. Endocrinology 2013; 154. [PMID: 23183174 PMCID: PMC3529385 DOI: 10.1210/en.2012-1640] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Enhanced de novo lipogenesis (DNL), an adult hepatic adaption, is seen with high carbohydrate or low-fat diets. We hypothesized that ad libitum intake after prenatal calorie restriction will result in adult-onset glucose intolerance and enhanced DNL with modified lipid metabolic gene expression profile. Stable isotopes were used in 15-month-old adult male rat offspring exposed to prenatal (IUGR), pre- and postnatal (IPGR), or postnatal (PNGR) caloric restriction vs. controls (CON). IUGR vs. CON were heavier with hepatomegaly but unchanged visceral white adipose tissue (WAT), glucose intolerant with reduced glucose-stimulated insulin secretion (GSIS), pancreatic β-cell mass, and total glucose clearance rate but unsuppressed hepatic glucose production. Liver glucose transporter (Glut) 1 and DNL increased with decreased hepatic acetyl-CoA carboxylase (ACC) and fatty acid synthase but increased WAT fatty acid transport protein-1 and peroxisomal proliferator-activated receptor-γ, resistin, and visfatin gene expression. In contrast, PNGR and IPGR were lighter, had reduced visceral WAT, and were glucose tolerant with unchanged hepatic glucose production but with increased GSIS, β-cell mass, glucose clearance rate, and WAT insulin receptor. Hepatic Glut1 and DNL were also increased in lean IPGR and PNGR with increased hepatic ACC, phosphorylated ACC, and pAMPK and reduced WAT fatty acid transport protein-1, peroxisomal proliferator-activated receptor-γ, and ACCα. We conclude the following: 1) the heavy, glucose-intolerant and insulin-resistant IUGR adult phenotype is ameliorated by postnatal caloric restriction; 2) increased DNL paralleling hepatic Glut1 is a biomarker of exposure to early caloric restriction rather than the adult metabolic status; 3) hepatic lipid enzyme expression reflects GSIS rather than DNL; and 4) WAT gene expression reflects an obesogenic vs. lean phenotype.
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Affiliation(s)
- Meena Garg
- Department of Pediatrics, Division of Neonatology and Developmental Biology, Neonatal Research Center, University of California- Los Angeles, Los Angeles, CA 90095-1752, USA.
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34
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Chen Y, Patel V, Bang S, Cohen N, Millar J, Kim SF. Maturation and activity of sterol regulatory element binding protein 1 is inhibited by acyl-CoA binding domain containing 3. PLoS One 2012; 7:e49906. [PMID: 23166793 PMCID: PMC3498211 DOI: 10.1371/journal.pone.0049906] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 10/15/2012] [Indexed: 12/23/2022] Open
Abstract
Imbalance of lipid metabolism has been linked with pathogenesis of a variety of human pathological conditions such as diabetes, obesity, cancer and neurodegeneration. Sterol regulatory element binding proteins (SREBPs) are the master transcription factors controlling the homeostasis of fatty acids and cholesterol in the body. Transcription, expression, and activity of SREBPs are regulated by various nutritional, hormonal or stressful stimuli, yet the molecular and cellular mechanisms involved in these adaptative responses remains elusive. In the present study, we found that overexpressed acyl-CoA binding domain containing 3 (ACBD3), a Golgi-associated protein, dramatically inhibited SREBP1-sensitive promoter activity of fatty acid synthase (FASN). Moreover, lipid deprivation-stimulated SREBP1 maturation was significantly attenuated by ACBD3. With cell fractionation, gene knockdown and immunoprecipitation assays, it was showed that ACBD3 blocked intracellular maturation of SREBP1 probably through directly binding with the lipid regulator rather than disrupted SREBP1-SCAP-Insig1 interaction. Further investigation revealed that acyl-CoA domain-containing N-terminal sequence of ACBD3 contributed to its inhibitory effects on the production of nuclear SREBP1. In addition, mRNA and protein levels of FASN and de novo palmitate biosynthesis were remarkably reduced in cells overexpressed with ACBD3. These findings suggest that ACBD3 plays an essential role in maintaining lipid homeostasis via regulating SREBP1's processing pathway and thus impacting cellular lipogenesis.
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Affiliation(s)
- Yong Chen
- Department of Psychiatry, Center for Neurobiology and Behavior, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Vishala Patel
- Metabolic Tracer Resource, Institute of Diabetes, Obesity & Metabolism, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sookhee Bang
- Department of Psychiatry, Center for Neurobiology and Behavior, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Natalie Cohen
- Department of Psychiatry, Center for Neurobiology and Behavior, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - John Millar
- Metabolic Tracer Resource, Institute of Diabetes, Obesity & Metabolism, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sangwon F. Kim
- Department of Psychiatry, Center for Neurobiology and Behavior, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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35
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Vaitheesvaran B, Yang L, Hartil K, Glaser S, Yazulla S, Bruce JE, Kurland IJ. Peripheral effects of FAAH deficiency on fuel and energy homeostasis: role of dysregulated lysine acetylation. PLoS One 2012; 7:e33717. [PMID: 22442717 PMCID: PMC3307749 DOI: 10.1371/journal.pone.0033717] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 02/16/2012] [Indexed: 12/01/2022] Open
Abstract
Background FAAH (fatty acid amide hydrolase), primarily expressed in the liver, hydrolyzes the endocannabinoids fatty acid ethanolamides (FAA). Human FAAH gene mutations are associated with increased body weight and obesity. In our present study, using targeted metabolite and lipid profiling, and new global acetylome profiling methodologies, we examined the role of the liver on fuel and energy homeostasis in whole body FAAH−/− mice. Methodology/Principal Findings FAAH−/− mice exhibit altered energy homeostasis demonstrated by decreased oxygen consumption (Indirect calorimetry). FAAH−/− mice are hyperinsulinemic and have adipose, skeletal and hepatic insulin resistance as indicated by stable isotope phenotyping (SIPHEN). Fed state skeletal muscle and liver triglyceride levels was increased 2–3 fold, while glycogen was decreased 42% and 57% respectively. Hepatic cholesterol synthesis was decreased 22% in FAAH−/− mice. Dysregulated hepatic FAAH−/− lysine acetylation was consistent with their metabolite profiling. Fasted to fed increases in hepatic FAAH−/− acetyl-CoA (85%, p<0.01) corresponded to similar increases in citrate levels (45%). Altered FAAH−/− mitochondrial malate dehydrogenase (MDH2) acetylation, which can affect the malate aspartate shuttle, was consistent with our observation of a 25% decrease in fed malate and aspartate levels. Decreased fasted but not fed dihydroxyacetone-P and glycerol-3-P levels in FAAH−/− mice was consistent with a compensating contribution from decreased acetylation of fed FAAH−/− aldolase B. Fed FAAH−/− alcohol dehydrogenase (ADH) acetylation was also decreased. Conclusions/Significance Whole body FAAH deletion contributes to a pre-diabetic phenotype by mechanisms resulting in impairment of hepatic glucose and lipid metabolism. FAAH−/− mice had altered hepatic lysine acetylation, the pattern sharing similarities with acetylation changes reported with chronic alcohol treatment. Dysregulated hepatic lysine acetylation seen with impaired FAA hydrolysis could support the liver's role in fostering the pre-diabetic state, and may reflect part of the mechanism underlying the hepatic effects of endocannabinoids in alcoholic liver disease mouse models.
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Affiliation(s)
- Bhavapriya Vaitheesvaran
- Department of Medicine, Stable Isotope and Metabolomics Core Facility, Albert Einstein College of Medicine Diabetes Center, Bronx, New York, United States of America
| | - Li Yang
- Department of Chemistry, Washington State University, Pullman, Washington, United States of America
| | - Kirsten Hartil
- Department of Medicine, Stable Isotope and Metabolomics Core Facility, Albert Einstein College of Medicine Diabetes Center, Bronx, New York, United States of America
| | - Sherrye Glaser
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, New York, United States of America
| | - Stephen Yazulla
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, New York, United States of America
| | - James E. Bruce
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Irwin J. Kurland
- Department of Medicine, Stable Isotope and Metabolomics Core Facility, Albert Einstein College of Medicine Diabetes Center, Bronx, New York, United States of America
- * E-mail:
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36
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Zhou H, Li W, Wang SP, Mendoza V, Rosa R, Hubert J, Herath K, McLaughlin T, Rohm RJ, Lassman ME, Wong KK, Johns DG, Previs SF, Hubbard BK, Roddy TP. Quantifying apoprotein synthesis in rodents: coupling LC-MS/MS analyses with the administration of labeled water. J Lipid Res 2012; 53:1223-31. [PMID: 22389331 DOI: 10.1194/jlr.d021295] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Stable isotope tracer studies of apoprotein flux in rodent models present difficulties as they require working with small volumes of plasma. We demonstrate the ability to measure apoprotein flux by administering either (2)H- or (18)O-labeled water to mice and then subjecting samples to LC-MS/MS analyses; we were able to simultaneously determine the labeling of several proteolytic peptides representing multiple apoproteins. Consistent with relative differences reported in the literature regarding apoprotein flux in humans, we found that the fractional synthetic rate of apoB is greater than apoA1 in mice. In addition, the method is suitable for quantifying acute changes in protein flux: we observed a stimulation of apoB production in mice following an intravenous injection of Intralipid and a decrease in apoB production in mice treated with an inhibitor of microsomal triglyceride transfer protein. In summary, we demonstrate a high-throughput method for studying apoprotein kinetics in rodent models. Although notable differences exist between lipoprotein profiles that are observed in rodents and humans, we expect that the method reported here has merit in studies of dyslipidemia as i) rodent models can be used to probe target engagement in cases where one aims to modulate apoprotein production and ii) the approach should be adaptable to studies in humans.
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Affiliation(s)
- Haihong Zhou
- Atherosclerosis, Merck Research Laboratories, Rahway, NJ 07065, USA
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37
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Scott DA, Richardson AD, Filipp FV, Knutzen CA, Chiang GG, Ronai ZA, Osterman AL, Smith JW. Comparative metabolic flux profiling of melanoma cell lines: beyond the Warburg effect. J Biol Chem 2011; 286:42626-42634. [PMID: 21998308 DOI: 10.1074/jbc.m111.282046] [Citation(s) in RCA: 256] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Metabolic rewiring is an established hallmark of cancer, but the details of this rewiring at a systems level are not well characterized. Here we acquire this insight in a melanoma cell line panel by tracking metabolic flux using isotopically labeled nutrients. Metabolic profiling and flux balance analysis were used to compare normal melanocytes to melanoma cell lines in both normoxic and hypoxic conditions. All melanoma cells exhibited the Warburg phenomenon; they used more glucose and produced more lactate than melanocytes. Other changes were observed in melanoma cells that are not described by the Warburg phenomenon. Hypoxic conditions increased fermentation of glucose to lactate in both melanocytes and melanoma cells (the Pasteur effect). However, metabolism was not strictly glycolytic, as the tricarboxylic acid (TCA) cycle was functional in all melanoma lines, even under hypoxia. Furthermore, glutamine was also a key nutrient providing a substantial anaplerotic contribution to the TCA cycle. In the WM35 melanoma line glutamine was metabolized in the "reverse" (reductive) direction in the TCA cycle, particularly under hypoxia. This reverse flux allowed the melanoma cells to synthesize fatty acids from glutamine while glucose was primarily converted to lactate. Altogether, this study, which is the first comprehensive comparative analysis of metabolism in melanoma cells, provides a foundation for targeting metabolism for therapeutic benefit in melanoma.
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Affiliation(s)
- David A Scott
- Cancer Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Adam D Richardson
- Cancer Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Fabian V Filipp
- Cancer Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Christine A Knutzen
- Cancer Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Gary G Chiang
- Cancer Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Ze'ev A Ronai
- Cancer Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Andrei L Osterman
- Cancer Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037.
| | - Jeffrey W Smith
- Cancer Research Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037
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38
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Wahjudi PN, K Yee J, Martinez SR, Zhang J, Teitell M, Nikolaenko L, Swerdloff R, Wang C, Lee WNP. Turnover of nonessential fatty acids in cardiolipin from the rat heart. J Lipid Res 2011; 52:2226-2233. [PMID: 21957203 DOI: 10.1194/jlr.m015966] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Cardiolipin (CL) is a unique phospholipid (PL) found in the mitochondria of mammalian cells. CL remodeling is accompanied by turnover of its fatty acid acyl groups. Abnormalities in CL remodeling have been found in Barth's syndrome, diabetes, and obesity. The objective of this study was to determine nonessential fatty acid turnover in CL and phosphatidylethanolamine (PE) in the rat heart in vivo. Sprague-Dawley rats were fed either a regular chow or a high-fat diet for 15 weeks, and consumed 6% deuterium-enriched drinking water as a tracer for 14 days. CL and PE were extracted from cardiac tissue and isolated by TLC. Fatty acids from CL, PE, and plasma were analyzed by GC/MS for deuterium incorporation. Results showed oleate and vaccenate turnover were the highest in CL whereas palmitate and stearate turnover were low. Among the nonessential fatty acids in PE, turnover of stearate and vaccenate were the highest. The high turnover rate in vaccenate was unexpected, because vaccenate previously had no known metabolic or physiologic function. In conclusion, the similarly high turnover rates of both oleate and vaccenate readily suggest that remodeling is an important functional aspect of PL metabolism in CL.
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Affiliation(s)
| | - Jennifer K Yee
- LA Biomedical Research Institute, Torrance, CA; Division of Endocrinology, Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | | | - Jin Zhang
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Michael Teitell
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Liana Nikolaenko
- LA Biomedical Research Institute, Torrance, CA; Division of Endocrinology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA and
| | - Ronald Swerdloff
- LA Biomedical Research Institute, Torrance, CA; Division of Endocrinology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA and
| | - Christina Wang
- LA Biomedical Research Institute, Torrance, CA; Division of Endocrinology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA and
| | - W N Paul Lee
- LA Biomedical Research Institute, Torrance, CA; Division of Endocrinology, Department of Pediatrics, David Geffen School of Medicine at UCLA, Los Angeles, CA.
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39
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Ye F, Lemieux H, Hoppel CL, Hanson RW, Hakimi P, Croniger CM, Puchowicz M, Anderson VE, Fujioka H, Stavnezer E. Peroxisome proliferator-activated receptor γ (PPARγ) mediates a Ski oncogene-induced shift from glycolysis to oxidative energy metabolism. J Biol Chem 2011; 286:40013-24. [PMID: 21917928 DOI: 10.1074/jbc.m111.292029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Overexpression of the Ski oncogene induces oncogenic transformation of chicken embryo fibroblasts (CEFs). However, unlike most other oncogene-transformed cells, Ski-transformed CEFs (Ski-CEFs) do not display the classical Warburg effect. On the contrary, Ski transformation reduced lactate production and glucose utilization in CEFs. Compared with CEFs, Ski-CEFs exhibited enhanced TCA cycle activity, fatty acid catabolism through β-oxidation, glutamate oxidation, oxygen consumption, as well as increased numbers and mass of mitochondria. Interestingly, expression of PPARγ, a key transcription factor that regulates adipogenesis and lipid metabolism, was dramatically elevated at both the mRNA and protein levels in Ski-CEFs. Accordingly, PPARγ target genes that are involved in lipid uptake, transport, and oxidation were also markedly up-regulated by Ski. Knocking down PPARγ in Ski-CEFs by RNA interference reversed the elevated expression of these PPARγ target genes, as well as the shift to oxidative metabolism and the increased mitochondrial biogenesis. Moreover, we found that Ski co-immunoprecipitates with PPARγ and co-activates PPARγ-driven transcription.
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Affiliation(s)
- Fang Ye
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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40
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Sos BC, Harris C, Nordstrom SM, Tran JL, Balázs M, Caplazi P, Febbraio M, Applegate MAB, Wagner KU, Weiss EJ. Abrogation of growth hormone secretion rescues fatty liver in mice with hepatocyte-specific deletion of JAK2. J Clin Invest 2011; 121:1412-23. [PMID: 21364286 DOI: 10.1172/jci42894] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2010] [Accepted: 01/05/2011] [Indexed: 12/23/2022] Open
Abstract
Non-alcoholic fatty liver disease is associated with multiple comorbid conditions, including diabetes, obesity, infection, and malnutrition. Mice with hepatocyte-specific disruption of growth hormone (GH) signaling develop fatty liver (FL), although the precise mechanism underlying this finding remains unknown. Because GH signals through JAK2, we developed mice bearing hepatocyte-specific deletion of JAK2 (referred to herein as JAK2L mice). These mice were lean, but displayed markedly elevated levels of GH, liver triglycerides (TGs), and plasma FFAs. Because GH is known to promote lipolysis, we crossed GH-deficient little mice to JAK2L mice, and this rescued the FL phenotype. Expression of the fatty acid transporter CD36 was dramatically increased in livers of JAK2L mice, as was expression of Pparg. Since GH signaling represses PPARγ expression and Cd36 is a known transcriptional target of PPARγ, we treated JAK2L mice with the PPARγ-specific antagonist GW9662. This resulted in reduced expression of liver Cd36 and decreased liver TG content. These results provide a mechanism for the FL observed in mice with liver-specific disruption in GH signaling and suggest that the development of FL depends on both GH-dependent increases in plasma FFA and increased hepatic uptake of FFA, likely mediated by increased expression of CD36.
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Affiliation(s)
- Brandon C Sos
- Cardiovascular Research Institute, UCSF, San Francisco, California 94158-9001, USA
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41
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Sos BC, Harris C, Nordstrom SM, Tran JL, Balázs M, Caplazi P, Febbraio M, Applegate MAB, Wagner KU, Weiss EJ. Abrogation of growth hormone secretion rescues fatty liver in mice with hepatocyte-specific deletion of JAK2. J Clin Invest 2011. [PMID: 21364286 DOI: 10.1172/jcl42894] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Non-alcoholic fatty liver disease is associated with multiple comorbid conditions, including diabetes, obesity, infection, and malnutrition. Mice with hepatocyte-specific disruption of growth hormone (GH) signaling develop fatty liver (FL), although the precise mechanism underlying this finding remains unknown. Because GH signals through JAK2, we developed mice bearing hepatocyte-specific deletion of JAK2 (referred to herein as JAK2L mice). These mice were lean, but displayed markedly elevated levels of GH, liver triglycerides (TGs), and plasma FFAs. Because GH is known to promote lipolysis, we crossed GH-deficient little mice to JAK2L mice, and this rescued the FL phenotype. Expression of the fatty acid transporter CD36 was dramatically increased in livers of JAK2L mice, as was expression of Pparg. Since GH signaling represses PPARγ expression and Cd36 is a known transcriptional target of PPARγ, we treated JAK2L mice with the PPARγ-specific antagonist GW9662. This resulted in reduced expression of liver Cd36 and decreased liver TG content. These results provide a mechanism for the FL observed in mice with liver-specific disruption in GH signaling and suggest that the development of FL depends on both GH-dependent increases in plasma FFA and increased hepatic uptake of FFA, likely mediated by increased expression of CD36.
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Affiliation(s)
- Brandon C Sos
- Cardiovascular Research Institute, UCSF, San Francisco, California 94158-9001, USA
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42
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Yee JK, Lee WNP, Han G, Ross MG, Desai M. Organ-specific alterations in fatty acid de novo synthesis and desaturation in a rat model of programmed obesity. Lipids Health Dis 2011; 10:72. [PMID: 21569358 PMCID: PMC3112422 DOI: 10.1186/1476-511x-10-72] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 05/11/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Small for gestational age (SGA) leads to increased risk of adult obesity and metabolic syndrome. Offspring exposed to 50% maternal food restriction in utero are born smaller than Controls (FR), catch-up in growth by the end of the nursing period, and become obese adults. The objective of the study was to determine stearoyl-CoA desaturase activity (SCD1) and rates of de novo fatty acid synthesis in young FR and Control offspring tissues at the end of the nursing period, as possible contributors to catch-up growth. METHODS From gestational day 10 to term, dams fed ad libitum (Control) or were 50% food-restricted to produce small FR pups. Control dams nursed all pups. At postnatal day 1 (p1) and p21, offspring body tissues were analyzed by GC/MS, and desaturation indices of palmitoleate/palmitate and oleate/stearate were calculated. SCD1 gene expression was determined by real-time PCR on adipose and liver. Offspring were enriched with deuterium that was given to dams in drinking water during lactation and de novo synthesis of offspring body tissues was determined at p21. Primary adipocyte cell cultures were established at p21 and exposed to U(13)C-glucose. RESULTS FR offspring exhibited higher desaturation index in p1 and p21 adipose tissue, but decreased desaturation index in liver at p21. SCD1 gene expression at p21 was correspondingly increased in adipose and decreased in liver. FR subcutaneous fat demonstrated increased de novo synthesis at p21. Primary cell cultures exhibited increased de novo synthesis in FR. CONCLUSIONS Adipose tissue is the first site to exhibit increased de novo synthesis and desaturase activity in FR. Therefore, abnormal lipogenesis is already present prior to onset of obesity during the period of catch-up growth. These abnormalities may contribute to future obesity development.
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Affiliation(s)
- Jennifer K Yee
- Department of Pediatrics, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Bldg RB-1, Harbor Box 446, Torrance, CA 90502, USA.
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Previs SF, Mahsut A, Kulick A, Dunn K, Andrews-Kelly G, Johnson C, Bhat G, Herath K, Miller PL, Wang SP, Azer K, Xu J, Johns DG, Hubbard BK, Roddy TP. Quantifying cholesterol synthesis in vivo using (2)H(2)O: enabling back-to-back studies in the same subject. J Lipid Res 2011; 52:1420-8. [PMID: 21498887 DOI: 10.1194/jlr.d014993] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The advantages of using (2)H(2)O to quantify cholesterol synthesis include i) homogeneous precursor labeling, ii) incorporation of (2)H via multiple pathways, and iii) the ability to perform long-term studies in free-living subjects. However, there are two concerns. First, the t(1/2) of tracer in body water presents a challenge when there is a need to acutely replicate measurements in the same subject. Second, assumptions are made regarding the number of hydrogens (n) that are incorporated during de novo synthesis. Our primary objective was to determine whether a step-based approach could be used to repeatedly study cholesterol synthesis a subject. We observed comparable changes in the (2)H-labeling of plasma water and total plasma cholesterol in African-Green monkeys that received five oral doses of (2)H(2)O, each dose separated by one week. Similar rates of cholesterol synthesis were estimated when comparing data in the group over the different weeks, but better reproducibility was observed when comparing replicate determinations of cholesterol synthesis in the same nonhuman primate during the respective dosing periods. Our secondary objective was to determine whether n depends on nutritional status in vivo; we observed n of ∼25 and ∼27 in mice fed a high-carbohydrate (HC) versus carbohydrate-free (CF) diet, respectively. We conclude that it is possible to acutely repeat studies of cholesterol synthesis using (2)H(2)O and that n is relatively constant.
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Paul Lee WN, Wahjudi PN, Xu J, Go VL. Tracer-based metabolomics: concepts and practices. Clin Biochem 2010; 43:1269-77. [PMID: 20713038 PMCID: PMC2952699 DOI: 10.1016/j.clinbiochem.2010.07.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 07/23/2010] [Accepted: 07/31/2010] [Indexed: 01/19/2023]
Abstract
Tracer-based metabolomics is a systems biology tool that combines advances in tracer methodology for physiological studies, high throughput "-omics" technologies and constraint based modeling of metabolic networks. It is different from the commonly known metabolomics or metabonomics in that it is a targeted approach based on a metabolic network model in cells. Because of its complexity, it is the least understood among the various "-omics." In this review, the development of concepts and practices of tracer-based metabolomics is traced from the early application of radioactive isotopes in metabolic studies to the recent application of stable isotopes and isotopomer analysis using mass spectrometry; and from the modeling of biochemical reactions using flux analysis to the recent theoretical formulation of the constraint based modeling. How these newer experimental methods and concepts of constraint-based modeling approaches can be applied to metabolic studies is illustrated by examples of studies in determining metabolic responses of cells to pharmacological agents and nutrient environment changes.
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Affiliation(s)
- W-N Paul Lee
- UCLA Center of Excellence for Pancreatic Diseases, Los Angeles Biomedical Research Institute, 1124 West Carson Torrance, CA 90502, USA.
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Millward CA, Desantis D, Hsieh CW, Heaney JD, Pisano S, Olswang Y, Reshef L, Beidelschies M, Puchowicz M, Croniger CM. Phosphoenolpyruvate carboxykinase (Pck1) helps regulate the triglyceride/fatty acid cycle and development of insulin resistance in mice. J Lipid Res 2010; 51:1452-63. [PMID: 20124556 DOI: 10.1194/jlr.m005363] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to investigate the role of the cytosolic form of phosphoenolpyruvate carboxykinase (Pck1) in the development of insulin resistance. Previous studies have shown that the roles of Pck1 in white adipose tissue (WAT) in glyceroneogenesis and reesterification of free fatty acids (FFA) to generate triglyceride are vital for the prevention of diabetes. We hypothesized that insulin resistance develops when dysregulation of Pck1 occurs in the triglyceride/fatty acid cycle, which regulates lipid synthesis and transport between adipose tissue and the liver. We examined this by analyzing mice with a deletion of the PPARgamma binding site in the promoter of Pck1 (PPARE(-/-)). This mutation reduced the fasting Pck1 mRNA expression in WAT in brown adipose tissue (BAT). To analyze insulin resistance, we performed hyperinsulinemic-euglycemic glucose clamp analyses. PPARE(-/-) mice were profoundly insulin resistant and had more FFA and glycerol released during the hyperinsulinemic-euglycemic clamp compared with wild-type mice (WT). Finally, we analyzed insulin secretion in isolated islets. We found a 2-fold increase in insulin secretion in the PPARE(-/-) mice at 16.7 mM glucose. Thus, the PPARE site in the Pck1 promoter is essential for maintenance of lipid metabolism and glucose homeostasis and disease prevention.
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Affiliation(s)
- Carrie A Millward
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106, USA
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Bruss MD, Khambatta CF, Ruby MA, Aggarwal I, Hellerstein MK. Calorie restriction increases fatty acid synthesis and whole body fat oxidation rates. Am J Physiol Endocrinol Metab 2010; 298:E108-16. [PMID: 19887594 PMCID: PMC4056782 DOI: 10.1152/ajpendo.00524.2009] [Citation(s) in RCA: 216] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calorie restriction (CR) increases longevity and retards the development of many chronic diseases, but the underlying metabolic signals are poorly understood. Increased fatty acid (FA) oxidation and reduced FA synthesis have been hypothesized to be important metabolic adaptations to CR. However, at metabolic steady state, FA oxidation must match FA intake plus synthesis; moreover, FA intake is low, not high, during CR. Therefore, it is not clear how FA dynamics are altered during CR. Accordingly, we measured food intake patterns, whole body fuel selection, endogenous FA synthesis, and gene expression in mice on CR. Within 2 days of CR being started, a shift to a cyclic, diurnal pattern of whole body FA metabolism occurred, with an initial phase of elevated endogenous FA synthesis [respiratory exchange ratio (RER) >1.10, lasting 4-6 h after food provision], followed by a prolonged phase of FA oxidation (RER = 0.70, lasting 18-20 h). CR mice oxidized four times as much fat per day as ad libitum (AL)-fed controls (367 +/- 19 vs. 97 +/- 14 mg/day, P < 0.001) despite reduced energy intake from fat. This increase in FA oxidation was balanced by a threefold increase in adipose tissue FA synthesis compared with AL. Expression of FA synthase and acetyl-CoA carboxylase mRNA were increased in adipose and liver in a time-dependent manner. We conclude that CR induces a surprising metabolic pattern characterized by periods of elevated FA synthesis alternating with periods of FA oxidation disproportionate to dietary FA intake. This pattern may have implications for oxidative damage and disease risk.
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Affiliation(s)
- Matthew D Bruss
- Dept. of Nutritional Sciences and Toxicology, Univ. of California at Berkeley, Morgan Hall, Rm. 309, Berkeley, CA 94720-3104, USA.
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Hsieh CW, Millward CA, DeSantis D, Pisano S, Machova J, Perales JC, Croniger CM. Reduced milk triglycerides in mice lacking phosphoenolpyruvate carboxykinase in mammary gland adipocytes and white adipose tissue contribute to the development of insulin resistance in pups. J Nutr 2009; 139:2257-65. [PMID: 19812223 PMCID: PMC2777474 DOI: 10.3945/jn.109.113092] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Obesity and type 2 diabetes are growing problems worldwide in adults and children. In this study, we focused on understanding the patterning of insulin resistance as a result of altered perinatal nutrition. We analyzed mice in which the binding site for PPARgamma was deleted from the promoter of the cytosolic phosphoenolpyruvate carboxykinase gene (Pck1) (PPARE(-/-)). We analyzed pups from dams with the same genotype as well as fostered and cross-fostered pups. Pck1 expression and triglyceride concentration in the milk were measured. The PPARE mutation reduced Pck1 expression in white adipose tissue (WAT) to 2.2% of wild type (WT) and reduced Pck1 expression in whole mammary gland tissue to 1% of WT. The female PPARE(-/-) mice had reduced lipid storage in mammary gland adipocytes and in WAT, resulting in a 40% reduction of milk triglycerides during lactation. Pups from PPARE(-/-) dams had insulin resistance as early as 14 d after birth, a condition that persisted into adulthood. WT pups fostered by PPARE(-/-) dams had lower body weights and plasma insulin concentrations compared with WT pups reared by WT dams. PPARE(-/-) pups fostered by WT dams had improved glucose clearance compared with pups raised by PPARE(-/-) dams. PPARE(+/-) and PPARE(-/-) dams also patterned newborn pups for reduced growth and insulin resistance in utero. Thus, the in utero environment and altered nutrition during the perinatal period cause epigenetic changes that persist into adulthood and contribute to the development of insulin resistance.
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Affiliation(s)
- Chang-Wen Hsieh
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106; and Biophysics Unit, Department de Ciències Fisiològuiques II, IDIBELL-University of Barcelona, Barcelona 08907, Spain
| | - Carrie A. Millward
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106; and Biophysics Unit, Department de Ciències Fisiològuiques II, IDIBELL-University of Barcelona, Barcelona 08907, Spain
| | - David DeSantis
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106; and Biophysics Unit, Department de Ciències Fisiològuiques II, IDIBELL-University of Barcelona, Barcelona 08907, Spain
| | - Sorana Pisano
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106; and Biophysics Unit, Department de Ciències Fisiològuiques II, IDIBELL-University of Barcelona, Barcelona 08907, Spain
| | - Jana Machova
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106; and Biophysics Unit, Department de Ciències Fisiològuiques II, IDIBELL-University of Barcelona, Barcelona 08907, Spain
| | - Jose C. Perales
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106; and Biophysics Unit, Department de Ciències Fisiològuiques II, IDIBELL-University of Barcelona, Barcelona 08907, Spain
| | - Colleen M. Croniger
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106; and Biophysics Unit, Department de Ciències Fisiològuiques II, IDIBELL-University of Barcelona, Barcelona 08907, Spain,To whom correspondence should be addressed. E-mail:
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Leavens KF, Easton RM, Shulman GI, Previs SF, Birnbaum MJ. Akt2 is required for hepatic lipid accumulation in models of insulin resistance. Cell Metab 2009; 10:405-18. [PMID: 19883618 PMCID: PMC2796129 DOI: 10.1016/j.cmet.2009.10.004] [Citation(s) in RCA: 221] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2009] [Revised: 08/26/2009] [Accepted: 10/05/2009] [Indexed: 02/08/2023]
Abstract
Insulin drives the global anabolic response to nutrient ingestion, regulating both carbohydrate and lipid metabolism. Previous studies have demonstrated that Akt2/protein kinase B is critical to insulin's control of glucose metabolism, but its role in lipid metabolism has remained controversial. Here, we show that Akt2 is required for hepatic lipid accumulation in obese, insulin-resistant states induced by either leptin deficiency or high-fat diet feeding. Lep(ob/ob) mice lacking hepatic Akt2 failed to amass triglycerides in their livers, associated with and most likely due to a decrease in lipogenic gene expression and de novo lipogenesis. However, Akt2 is also required for steatotic pathways unrelated to fatty acid synthesis, as mice fed high-fat diet had reduced liver triglycerides in the absence of hepatic Akt2 but did not exhibit changes in lipogenesis. These data demonstrate that Akt2 is a requisite component of the insulin-dependent regulation of lipid metabolism during insulin resistance.
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Affiliation(s)
- Karla F Leavens
- Department of Medicine, Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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Lane AN, Fan TWM, Xie Z, Moseley HNB, Higashi RM. Isotopomer analysis of lipid biosynthesis by high resolution mass spectrometry and NMR. Anal Chim Acta 2009; 651:201-8. [PMID: 19782812 PMCID: PMC2757635 DOI: 10.1016/j.aca.2009.08.032] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2009] [Revised: 08/22/2009] [Accepted: 08/24/2009] [Indexed: 10/20/2022]
Abstract
We have coupled 2D-NMR and infusion FT-ICR-MS with computer-assisted assignment to profile 13C-isotopologues of glycerophospholipids (GPL) directly in crude cell extracts, resulting in very high information throughput of >3000 isobaric molecules in a few minutes. A mass accuracy of better than 1 ppm combined with a resolution of 100,000 at the measured m/z was required to distinguish isotopomers from other GPL structures. Isotopologue analysis of GPLs extracted from LCC2 breast cancer cells grown on [U-13C]-glucose provided a rich trove of information about the biosynthesis and turnover of the GPLs. The isotopologue intensity ratios from the FT-ICR-MS were accurate to approximately 1% or better based on natural abundance background, and depended on the signal-to-nose ratio. The time course of incorporation of 13C from [U-13C]-glucose into a particular phosphatidylcholine was analyzed in detail, to provide a quantitative measure of the sizes of glycerol, acetyl CoA and total GPL pools in growing LCC2 cells. Independent and complementary analysis of the positional 13C enrichment in the glycerol and fatty acyl chains obtained from high resolution 2D NMR was used to verify key aspects of the model. This technology enables simple and rapid sample preparation, has rapid analysis, and is generally applicable to unfractionated GPLs of almost any head group, and to mixtures of other classes of metabolites.
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Affiliation(s)
- Andrew N Lane
- JG Brown Cancer Center, 529 S. Jackson Street, Louisville, KY 40202, USA.
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Bederman IR, Foy S, Chandramouli V, Alexander JC, Previs SF. Triglyceride synthesis in epididymal adipose tissue: contribution of glucose and non-glucose carbon sources. J Biol Chem 2008; 284:6101-8. [PMID: 19114707 DOI: 10.1074/jbc.m808668200] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The obesity epidemic has generated interest in determining the contribution of various pathways to triglyceride synthesis, including an elucidation of the origin of triglyceride fatty acids and triglyceride glycerol. We hypothesized that a dietary intervention would demonstrate the importance of using glucose versus non-glucose carbon sources to synthesize triglycerides in white adipose tissue. C57BL/6J mice were fed either a low fat, high carbohydrate (HC) diet or a high fat, carbohydrate-free (CF) diet and maintained on 2H2O (to determine total triglyceride dynamics) or infused with [6,6-(2)H]glucose (to quantify the contribution of glucose to triglyceride glycerol). The 2H2O labeling data demonstrate that although de novo lipogenesis contributed approximately 80% versus approximately 5% to the pool of triglyceride palmitate in HC- versus CF-fed mice, the epididymal adipose tissue synthesized approximately 1.5-fold more triglyceride in CF- versus HC-fed mice, i.e. 37+/-5 versus 25+/-3 micromolxday(-1). The [6,6-(2)H]glucose labeling data demonstrate that approximately 69 and approximately 28% of triglyceride glycerol is synthesized from glucose in HC- versus CF-fed mice, respectively. Although these data are consistent with the notion that non-glucose carbon sources (e.g. glyceroneogenesis) can make substantial contributions to the synthesis of triglyceride glycerol (i.e. the absolute synthesis of triglyceride glycerol from non-glucose substrates increased from approximately 8 to approximately 26 micromolxday(-1) in HC- versus CF-fed mice), these observations suggest (i) the importance of nutritional status in affecting flux rates and (ii) the operation of a glycerol-glucose cycle.
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Affiliation(s)
- Ilya R Bederman
- Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106, USA
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