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De Vos K, Mavrogiannis A, Wolters JC, Schlenner S, Wierda K, Cortés Calabuig Á, Chinnaraj R, Dermesrobian V, Armoudjian Y, Jacquemyn M, Corthout N, Daelemans D, Annaert P. Tankyrase1/2 inhibitor XAV-939 reverts EMT and suggests that PARylation partially regulates aerobic activities in human hepatocytes and HepG2 cells. Biochem Pharmacol 2024; 227:116445. [PMID: 39053638 DOI: 10.1016/j.bcp.2024.116445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 07/16/2024] [Accepted: 07/18/2024] [Indexed: 07/27/2024]
Abstract
The maintenance of a highly functional metabolic epithelium in vitro is challenging. Metabolic impairments in primary human hepatocytes (PHHs) over time is primarily due to epithelial-to-mesenchymal transitioning (EMT). The immature hepatoma cell line HepG2 was used as an in vitro model to explore strategies for enhancing the hepatic phenotype. The phenotypic characterization includes measuring the urea cycle, lipid storage, tricarboxylic acid-related metabolites, reactive oxygen species, endoplasmic reticulum calcium efflux, mitochondrial membrane potentials, oxygen consumptions rate, and CYP450 biotransformation capacity. Expression studies were performed with transcriptomics, co-immunoprecipitation and proteomics. CRISPR/Cas9 was also employed to genetically engineer HepG2 cells. After confirming that PHHs develop an EMT phenotype, expression of tankyrase1/2 was found to increase over time. EMT was reverted when blocking tankyrases1/2-dependent poly-ADP-ribosylation (PARylation) activity, by biochemical and genetic perturbation. Wnt/β-catenin inhibitor XAV-939 blocks tankyrase1/2 and treatment elevated several oxygen-consuming reactions (electron-transport chain, OXHPOS, CYP450 mono-oxidase activity, phase I/II xenobiotic biotransformation, and prandial turnover), suggesting that cell metabolism was enhanced. Glutathione-dependent redox homeostasis was also significantly improved in the XAV-939 condition. Oxygen consumption rate and proteomics experiments in tankyrase1/2 double knockout HepG2 cells then uncovered PARylation as master regulator of aerobic-dependent cell respiration. Furthermore, novel tankyrase1/2-dependent PARylation targets, including mitochondrial DLST, and OGDH, were revealed. This work exposed a new mechanistic framework by linking PARylation to respiration and metabolism, thereby broadening the current understanding that underlies these vital processes. XAV-939 poses an immediate and straightforward strategy to improve aerobic activities, and metabolism, in (immature) cell cultures.
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Affiliation(s)
- Kristof De Vos
- Laboratory of Drug Delivery and Disposition, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Adamantios Mavrogiannis
- Adaptive Immunology, Department of Microbiology, Immunology and Transplantation, KU Leuven, 3000 Leuven, Belgium
| | - Justina Clarinda Wolters
- Section Systems Medicine of Metabolism and Signaling, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen 9713 AV, the Netherlands
| | - Susan Schlenner
- Adaptive Immunology, Department of Microbiology, Immunology and Transplantation, KU Leuven, 3000 Leuven, Belgium
| | - Keimpe Wierda
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Electrophysiology Unit, VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | | | - Reena Chinnaraj
- KU Leuven Flow and Mass Cytometry Facility, Department of Microbiology, Immunology and Transplantation, KU Leuven, 3000 Leuven, Belgium
| | - Vera Dermesrobian
- KU Leuven Flow and Mass Cytometry Facility, Department of Microbiology, Immunology and Transplantation, KU Leuven, 3000 Leuven, Belgium
| | | | - Maarten Jacquemyn
- Laboratory of Virology and Chemotherapy, Department of Microbiology, Immunology and Transplantation, KU Leuven, Rega Institute, 3000 Leuven, Belgium
| | - Nikky Corthout
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; VIB Bio Imaging Core, 3000 Leuven, Belgium
| | - Dirk Daelemans
- Laboratory of Virology and Chemotherapy, Department of Microbiology, Immunology and Transplantation, KU Leuven, Rega Institute, 3000 Leuven, Belgium
| | - Pieter Annaert
- Laboratory of Drug Delivery and Disposition, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium; BioNotus GCV, 2845 Niel, Belgium.
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Aspacio D, Zhang Y, Cui Y, Luu E, King E, Black WB, Perea S, Zhu Q, Wu Y, Luo R, Siegel JB, Li H. Shifting redox reaction equilibria on demand using an orthogonal redox cofactor. Nat Chem Biol 2024:10.1038/s41589-024-01702-5. [PMID: 39138383 DOI: 10.1038/s41589-024-01702-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 07/16/2024] [Indexed: 08/15/2024]
Abstract
Nature's two redox cofactors, nicotinamide adenine dinucleotide (NAD+) and nicotinamide adenine dinucleotide phosphate (NADP+), are held at different reduction potentials, driving catabolism and anabolism in opposite directions. In biomanufacturing, there is a need to flexibly control redox reaction direction decoupled from catabolism and anabolism. We established nicotinamide mononucleotide (NMN+) as a noncanonical cofactor orthogonal to NAD(P)+. Here we present the development of Nox Ortho, a reduced NMN+ (NMNH)-specific oxidase, that completes the toolkit to modulate NMNH:NMN+ ratio together with an NMN+-specific glucose dehydrogenase (GDH Ortho). The design principle discovered from Nox Ortho engineering and modeling is facilely translated onto six different enzymes to create NMN(H)-orthogonal biocatalysts with a consistent ~103-106-fold cofactor specificity switch from NAD(P)+ to NMN+. We assemble these enzymes to produce stereo-pure 2,3-butanediol in cell-free systems and in Escherichia coli, enabled by NMN(H)'s distinct redox ratio firmly set by its designated driving forces, decoupled from both NAD(H) and NADP(H).
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Affiliation(s)
- Derek Aspacio
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, CA, USA
| | - Yulai Zhang
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, CA, USA
| | - Youtian Cui
- Genome Center, University of California, Davis, Davis, CA, USA
| | - Emma Luu
- Genome Center, University of California, Davis, Davis, CA, USA
| | - Edward King
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, USA
| | - William B Black
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, CA, USA
| | - Sean Perea
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, CA, USA
| | - Qiang Zhu
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, CA, USA
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, USA
- Department of Material Science and Engineering, University of California, Irvine, Irvine, CA, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Yongxian Wu
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, CA, USA
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, USA
- Department of Material Science and Engineering, University of California, Irvine, Irvine, CA, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Ray Luo
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, CA, USA
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, USA
- Department of Material Science and Engineering, University of California, Irvine, Irvine, CA, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA
| | - Justin B Siegel
- Genome Center, University of California, Davis, Davis, CA, USA
- Department of Chemistry, University of California, Davis, Davis, CA, USA
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, USA
| | - Han Li
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, CA, USA.
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA.
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA, USA.
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3
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Deja S, Fletcher JA, Kim CW, Kucejova B, Fu X, Mizerska M, Villegas M, Pudelko-Malik N, Browder N, Inigo-Vollmer M, Menezes CJ, Mishra P, Berglund ED, Browning JD, Thyfault JP, Young JD, Horton JD, Burgess SC. Hepatic malonyl-CoA synthesis restrains gluconeogenesis by suppressing fat oxidation, pyruvate carboxylation, and amino acid availability. Cell Metab 2024; 36:1088-1104.e12. [PMID: 38447582 PMCID: PMC11081827 DOI: 10.1016/j.cmet.2024.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 12/10/2023] [Accepted: 02/09/2024] [Indexed: 03/08/2024]
Abstract
Acetyl-CoA carboxylase (ACC) promotes prandial liver metabolism by producing malonyl-CoA, a substrate for de novo lipogenesis and an inhibitor of CPT-1-mediated fat oxidation. We report that inhibition of ACC also produces unexpected secondary effects on metabolism. Liver-specific double ACC1/2 knockout (LDKO) or pharmacologic inhibition of ACC increased anaplerosis, tricarboxylic acid (TCA) cycle intermediates, and gluconeogenesis by activating hepatic CPT-1 and pyruvate carboxylase flux in the fed state. Fasting should have marginalized the role of ACC, but LDKO mice maintained elevated TCA cycle intermediates and preserved glycemia during fasting. These effects were accompanied by a compensatory induction of proteolysis and increased amino acid supply for gluconeogenesis, which was offset by increased protein synthesis during feeding. Such adaptations may be related to Nrf2 activity, which was induced by ACC inhibition and correlated with fasting amino acids. The findings reveal unexpected roles for malonyl-CoA synthesis in liver and provide insight into the broader effects of pharmacologic ACC inhibition.
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Affiliation(s)
- Stanislaw Deja
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Justin A Fletcher
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA; Department of Clinical Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Chai-Wan Kim
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Blanka Kucejova
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Xiaorong Fu
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA; Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Monika Mizerska
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Morgan Villegas
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Natalia Pudelko-Malik
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA; Department of Biochemistry, Molecular Biology and Biotechnology, Faculty of Chemistry, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Nicholas Browder
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Melissa Inigo-Vollmer
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Cameron J Menezes
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Prashant Mishra
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Eric D Berglund
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Jeffrey D Browning
- Department of Clinical Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - John P Thyfault
- Departments of Cell Biology and Physiology, Internal Medicine and KU Diabetes Institute, Kansas Medical Center, Kansas City, KS, USA
| | - Jamey D Young
- Department of Chemical and Biomolecular Engineering, Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37235, USA
| | - Jay D Horton
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA; Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA.
| | - Shawn C Burgess
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA.
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Aspacio D, Zhang Y, Cui Y, King E, Black WB, Perea S, Luu E, Siegel JB, Li H. Shifting Redox Reaction Equilibria on Demand Using an Orthogonal Redox Cofactor. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.29.555398. [PMID: 37693387 PMCID: PMC10491207 DOI: 10.1101/2023.08.29.555398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Natural metabolism relies on chemical compartmentalization of two redox cofactors, NAD+ and NADP+, to orchestrate life-essential redox reaction directions. However, in whole cells the reliance on these canonical cofactors limits flexible control of redox reaction direction as these reactions are permanently tied to catabolism or anabolism. In cell-free systems, NADP+ is too expensive in large scale. We have previously reported the use of nicotinamide mononucleotide, (NMN+) as a low-cost, noncanonical redox cofactor capable of specific electron delivery to diverse chemistries. Here, we present Nox Ortho, an NMNH-specific water-forming oxidase, that completes the toolkit to modulate NMNH/NMN+ ratio. This work uncovers an enzyme design principle that succeeds in parallel engineering of six butanediol dehydrogenases as NMN(H)-orthogonal biocatalysts consistently with a 103 - 106 -fold cofactor specificity switch from NAD(P)+ to NMN+. We combine these to produce chiral-pure 2,3-butanediol (Bdo) isomers without interference from NAD(H) or NADP(H) in vitro and in E. coli cells. We establish that NMN(H) can be held at a distinct redox ratio on demand, decoupled from both NAD(H) and NADP(H) redox ratios in vitro and in vivo.
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Affiliation(s)
- Derek Aspacio
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697-3900, United States
| | - Yulai Zhang
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697-3900, United States
| | - Youtian Cui
- Genome Center, University of California, Davis, Davis, California 95616, United States
| | - Edward King
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, California 92697-3900, United States
| | - William B. Black
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697-3900, United States
| | - Sean Perea
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697-3900, United States
| | - Emma Luu
- Genome Center, University of California, Davis, Davis, California 95616, United States
| | - Justin B. Siegel
- Genome Center, University of California, Davis, Davis, California 95616, United States
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, California 95616, United States
| | - Han Li
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697-3900, United States
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92697-3900, United States
- Department of Biological Chemistry, University of California, Irvine, Irvine, California 92697-3900, United States
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Park JS, Perl A. Endosome Traffic Modulates Pro-Inflammatory Signal Transduction in CD4 + T Cells-Implications for the Pathogenesis of Systemic Lupus Erythematosus. Int J Mol Sci 2023; 24:10749. [PMID: 37445926 DOI: 10.3390/ijms241310749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/10/2023] [Accepted: 06/26/2023] [Indexed: 07/15/2023] Open
Abstract
Endocytic recycling regulates the cell surface receptor composition of the plasma membrane. The surface expression levels of the T cell receptor (TCR), in concert with signal transducing co-receptors, regulate T cell responses, such as proliferation, differentiation, and cytokine production. Altered TCR expression contributes to pro-inflammatory skewing, which is a hallmark of autoimmune diseases, such as systemic lupus erythematosus (SLE), defined by a reduced function of regulatory T cells (Tregs) and the expansion of CD4+ helper T (Th) cells. The ensuing secretion of inflammatory cytokines, such as interferon-γ and interleukin (IL)-4, IL-17, IL-21, and IL-23, trigger autoantibody production and tissue infiltration by cells of the adaptive and innate immune system that induce organ damage. Endocytic recycling influences immunological synapse formation by CD4+ T lymphocytes, signal transduction from crosslinked surface receptors through recruitment of adaptor molecules, intracellular traffic of organelles, and the generation of metabolites to support growth, cytokine production, and epigenetic control of DNA replication and gene expression in the cell nucleus. This review will delineate checkpoints of endosome traffic that can be targeted for therapeutic interventions in autoimmune and other disease conditions.
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Affiliation(s)
- Joy S Park
- Department of Medicine, Norton College of Medicine, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA
- Department of Biochemistry and Molecular Biology, Norton College of Medicine, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA
| | - Andras Perl
- Department of Medicine, Norton College of Medicine, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA
- Department of Biochemistry and Molecular Biology, Norton College of Medicine, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA
- Department of Microbiology and Immunology, Norton College of Medicine, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA
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Surugihalli C, Muralidaran V, Ryan CE, Patel K, Zhao D, Sunny NE. Branched-chain amino acids alter cellular redox to induce lipid oxidation and reduce de novo lipogenesis in the liver. Am J Physiol Endocrinol Metab 2023; 324:E299-E313. [PMID: 36791321 PMCID: PMC10042599 DOI: 10.1152/ajpendo.00307.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/30/2023] [Accepted: 02/08/2023] [Indexed: 02/17/2023]
Abstract
Metabolic and molecular interactions between branched-chain amino acid (BCAA) and lipid metabolism are evident in insulin-resistant tissues. However, it remains unclear whether insulin resistance is a prerequisite for these relationships and whether BCAAs or their metabolic intermediates can modulate hepatic lipid oxidation and synthesis. We hypothesized that BCAAs can alter hepatic oxidative function and de novo lipogenesis, independent of them being anaplerotic substrates for the mitochondria. Mice (C57BL/6NJ) were reared on a low-fat (LF), LF diet plus 1.5X BCAAs (LB), high-fat (HF) or HF diet plus 1.5X BCAAs (HB) for 12 wk. Hepatic metabolism was profiled utilizing stable isotopes coupled to mass spectrometry and nuclear magnetic resonance, together with fed-to-fasted changes in gene and protein expression. A greater induction of lipid oxidation and ketogenesis on fasting was evident in the BCAA-supplemented, insulin-sensitive livers from LB mice, whereas their rates of hepatic de novo lipogenesis remained lower than their LF counterparts. Onset of insulin resistance in HF and HB mice livers blunted these responses. Whole body turnover of BCAAs and their ketoacids, their serum concentrations, and the ketogenic flux from BCAA catabolism, all remained similar between fasted LF and LB mice. This suggested that the impact of BCAAs on lipid metabolism can occur independent of them or their degradation products fueling anaplerosis through the liver mitochondria. Furthermore, the greater induction of lipid oxidation in the LB livers accompanied higher mitochondrial NADH/NAD+ ratio and higher fed-to-fasting phosphorylation of AMPKα and ACC. Taken together, our results provide evidence that BCAA supplementation, under conditions of insulin sensitivity, improved the feeding-to-fasting induction of hepatic lipid oxidation through changes in cellular redox, thus providing a favorable biochemical environment for flux through β-oxidation and lower de novo lipogenesis.NEW & NOTEWORTHY Branched-chain amino acids (BCAAs) have been shown to modulate lipid metabolic networks in various tissues, especially during insulin resistance. In this study we show that the dietary supplementation of BCAAs to normal, insulin-sensitive mice resulted in higher mitochondrial NADH:NAD+ ratios and AMPK activation in the liver. This change in the cellular redox status provided an optimal metabolic milieu to increase fatty acid oxidation while keeping the rates of de novo lipogenesis lower in the BCAA-supplemented mice livers.
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Affiliation(s)
- Chaitra Surugihalli
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, United States
| | - Vaishna Muralidaran
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, United States
| | - Caitlin E Ryan
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, United States
| | - Kruti Patel
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, United States
| | - David Zhao
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, United States
| | - Nishanth E Sunny
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, United States
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7
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Chen X, Liu L, Kang S, Gnanaprakasam JNR, Wang R. The lactate dehydrogenase (LDH) isoenzyme spectrum enables optimally controlling T cell glycolysis and differentiation. SCIENCE ADVANCES 2023; 9:eadd9554. [PMID: 36961904 PMCID: PMC10038341 DOI: 10.1126/sciadv.add9554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
Isoenzyme divergence is a prevalent mechanism governing tissue-specific and developmental stage-specific metabolism in mammals. The lactate dehydrogenase (LDH) isoenzyme spectrum reflects the tissue-specific metabolic status. We found that three tetrameric isoenzymes composed of LDHA and LDHB (LDH-3/4/5) comprise the LDH spectrum in T cells. Genetically deleting LDHA or LDHB altered the isoenzyme spectrum by removing all heterotetramers and leaving T cells with LDH-1 (the homotetramer of LDHB) or LDH-5 (the homotetramer of LDHA), respectively. Accordingly, deleting LDHA suppressed glycolysis, cell proliferation, and differentiation. Unexpectedly, deleting LDHB enhanced glycolysis but suppressed T cell differentiation, indicating that an optimal zone of glycolytic activity is required to maintain cell fitness. Mechanistically, the LDH isoenzyme spectrum imposed by LDHA and LDHB is necessary to optimize glycolysis to maintain a balanced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide hydrogen pool. Our results suggest that the LDH isoenzyme spectrum enables "Goldilocks levels" of glycolytic and redox activity to control T cell differentiation.
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Affiliation(s)
- Xuyong Chen
- Center for Childhood Cancer and Blood Diseases, Hematology/Oncology and BMT, Abigail Wexner Research Institute at Nationwide Children’s Hospital, The Ohio State University, Columbus, OH, USA
| | | | | | - JN Rashida Gnanaprakasam
- Center for Childhood Cancer and Blood Diseases, Hematology/Oncology and BMT, Abigail Wexner Research Institute at Nationwide Children’s Hospital, The Ohio State University, Columbus, OH, USA
| | - Ruoning Wang
- Center for Childhood Cancer and Blood Diseases, Hematology/Oncology and BMT, Abigail Wexner Research Institute at Nationwide Children’s Hospital, The Ohio State University, Columbus, OH, USA
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8
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NAD + Metabolism and Interventions in Premature Renal Aging and Chronic Kidney Disease. Cells 2022; 12:cells12010021. [PMID: 36611814 PMCID: PMC9818486 DOI: 10.3390/cells12010021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/17/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Premature aging causes morphological and functional changes in the kidney, leading to chronic kidney disease (CKD). CKD is a global public health issue with far-reaching consequences, including cardio-vascular complications, increased frailty, shortened lifespan and a heightened risk of kidney failure. Dialysis or transplantation are lifesaving therapies, but they can also be debilitating. Currently, no cure is available for CKD, despite ongoing efforts to identify clinical biomarkers of premature renal aging and molecular pathways of disease progression. Kidney proximal tubular epithelial cells (PTECs) have high energy demand, and disruption of their energy homeostasis has been linked to the progression of kidney disease. Consequently, metabolic reprogramming of PTECs is gaining interest as a therapeutic tool. Preclinical and clinical evidence is emerging that NAD+ homeostasis, crucial for PTECs' oxidative metabolism, is impaired in CKD, and administration of dietary NAD+ precursors could have a prophylactic role against age-related kidney disease. This review describes the biology of NAD+ in the kidney, including its precursors and cellular roles, and discusses the importance of NAD+ homeostasis for renal health. Furthermore, we provide a comprehensive summary of preclinical and clinical studies aimed at increasing NAD+ levels in premature renal aging and CKD.
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Sonntag T, Ancel S, Karaz S, Cichosz P, Jacot G, Giner MP, Sanchez-Garcia JL, Pannérec A, Moco S, Sorrentino V, Cantó C, Feige JN. Nicotinamide riboside kinases regulate skeletal muscle fiber-type specification and are rate-limiting for metabolic adaptations during regeneration. Front Cell Dev Biol 2022; 10:1049653. [PMID: 36438552 PMCID: PMC9682158 DOI: 10.3389/fcell.2022.1049653] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 10/19/2022] [Indexed: 08/27/2023] Open
Abstract
Nicotinamide riboside kinases (NRKs) control the conversion of dietary Nicotinamide Riboside (NR) to NAD+, but little is known about their contribution to endogenous NAD+ turnover and muscle plasticity during skeletal muscle growth and remodeling. Using NRK1/2 double KO (NRKdKO) mice, we investigated the influence of NRKs on NAD+ metabolism and muscle homeostasis, and on the response to neurogenic muscle atrophy and regeneration following muscle injury. Muscles from NRKdKO animals have altered nicotinamide (NAM) salvage and a decrease in mitochondrial content. In single myonuclei RNAseq of skeletal muscle, NRK2 mRNA expression is restricted to type IIx muscle fibers, and perturbed NAD+ turnover and mitochondrial metabolism shifts the fiber type composition of NRKdKO muscle to fast glycolytic IIB fibers. NRKdKO does not influence muscle atrophy during denervation but alters muscle repair after myofiber injury. During regeneration, muscle stem cells (MuSCs) from NRKdKO animals hyper-proliferate but fail to differentiate. NRKdKO also alters the recovery of NAD+ during muscle regeneration as well as mitochondrial adaptations and extracellular matrix remodeling required for tissue repair. These metabolic perturbations result in a transient delay of muscle regeneration which normalizes during myofiber maturation at late stages of regeneration via over-compensation of anabolic IGF1-Akt signaling. Altogether, we demonstrate that NAD+ synthesis controls mitochondrial metabolism and fiber type composition via NRK1/2 and is rate-limiting for myogenic commitment and mitochondrial maturation during skeletal muscle repair.
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Affiliation(s)
- Tanja Sonntag
- Nestle Institute of Health Sciences, Lausanne, Switzerland
- EPFL School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Sara Ancel
- Nestle Institute of Health Sciences, Lausanne, Switzerland
- EPFL School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Sonia Karaz
- Nestle Institute of Health Sciences, Lausanne, Switzerland
| | | | | | - Maria Pilar Giner
- Nestle Institute of Food Safety & Analytical Sciences, Lausanne, Switzerland
| | | | - Alice Pannérec
- Nestle Institute of Health Sciences, Lausanne, Switzerland
| | - Sofia Moco
- Nestle Institute of Food Safety & Analytical Sciences, Lausanne, Switzerland
| | | | - Carles Cantó
- Nestle Institute of Health Sciences, Lausanne, Switzerland
- EPFL School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Jérôme N. Feige
- Nestle Institute of Health Sciences, Lausanne, Switzerland
- EPFL School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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10
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Discovery of small-molecule activators of nicotinamide phosphoribosyltransferase (NAMPT) and their preclinical neuroprotective activity. Cell Res 2022; 32:570-584. [PMID: 35459935 DOI: 10.1038/s41422-022-00651-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 02/19/2022] [Indexed: 01/07/2023] Open
Abstract
The decline of nicotinamide adenine dinucleotide (NAD) occurs in a variety of human pathologies including neurodegeneration. NAD-boosting agents can provide neuroprotective benefits. Here, we report the discovery and development of a class of potent activators (NATs) of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the NAD salvage pathway. We obtained the crystal structure of NAMPT in complex with the NAT, which defined the allosteric action of NAT near the enzyme active site. The optimization of NAT further revealed the critical role of K189 residue in boosting NAMPT activity. NATs effectively increased intracellular levels of NAD and induced subsequent metabolic and transcriptional reprogramming. Importantly, NATs exhibited strong neuroprotective efficacy in a mouse model of chemotherapy-induced peripheral neuropathy (CIPN) without any overt toxicity. These findings demonstrate the potential of NATs in the treatment of neurodegenerative diseases or conditions associated with NAD level decline.
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11
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Glucose-6-phosphatase catalytic subunit 2 negatively regulates glucose oxidation and insulin secretion in pancreatic β-cells. J Biol Chem 2022; 298:101729. [PMID: 35176280 PMCID: PMC8941207 DOI: 10.1016/j.jbc.2022.101729] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 02/11/2022] [Accepted: 02/12/2022] [Indexed: 12/11/2022] Open
Abstract
Elevated fasting blood glucose (FBG) is associated with increased risks of developing type 2 diabetes (T2D) and cardiovascular-associated mortality. G6PC2 is predominantly expressed in islets, encodes a glucose-6-phosphatase catalytic subunit that converts glucose-6-phosphate (G6P) to glucose, and has been linked with variations in FBG in genome-wide association studies. Deletion of G6pc2 in mice has been shown to lower FBG without affecting fasting plasma insulin levels in vivo. At 5 mM glucose, pancreatic islets from G6pc2 knockout (KO) mice exhibit no glucose cycling, increased glycolytic flux, and enhanced glucose-stimulated insulin secretion (GSIS). However, the broader effects of G6pc2 KO on β-cell metabolism and redox regulation are unknown. Here we used CRISPR/Cas9 gene editing and metabolic flux analysis in βTC3 cells, a murine pancreatic β-cell line, to examine the role of G6pc2 in regulating glycolytic and mitochondrial fluxes. We found that deletion of G6pc2 led to ∼60% increases in glycolytic and citric acid cycle (CAC) fluxes at both 5 and 11 mM glucose concentrations. Furthermore, intracellular insulin content and GSIS were enhanced by approximately two-fold, along with increased cytosolic redox potential and reductive carboxylation flux. Normalization of fluxes relative to net glucose uptake revealed upregulation in two NADPH-producing pathways in the CAC. These results demonstrate that G6pc2 regulates GSIS by modulating not only glycolysis but also, independently, citric acid cycle activity in β-cells. Overall, our findings implicate G6PC2 as a potential therapeutic target for enhancing insulin secretion and lowering FBG, which could benefit individuals with prediabetes, T2D, and obesity.
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12
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Being a scientist. Eur J Clin Nutr 2022:10.1038/s41430-022-01079-5. [PMID: 35105944 DOI: 10.1038/s41430-022-01079-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/15/2021] [Accepted: 01/12/2022] [Indexed: 11/08/2022]
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13
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Alganem K, Hamoud AR, Creeden JF, Henkel ND, Imami AS, Joyce AW, Ryan V WG, Rethman JB, Shukla R, O'Donovan SM, Meller J, McCullumsmith R. The active kinome: The modern view of how active protein kinase networks fit in biological research. Curr Opin Pharmacol 2022; 62:117-129. [PMID: 34968947 PMCID: PMC9438800 DOI: 10.1016/j.coph.2021.11.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 10/21/2021] [Accepted: 11/12/2021] [Indexed: 02/03/2023]
Abstract
Biological regulatory networks are dynamic, intertwined, and complex systems making them challenging to study. While quantitative measurements of transcripts and proteins are key to investigate the state of a biological system, they do not inform the "active" state of regulatory networks. In consideration of that fact, "functional" proteomics assessments are needed to decipher active regulatory processes. Phosphorylation, a key post-translation modification, is a reversible regulatory mechanism that controls the functional state of proteins. Recent advancements of high-throughput protein kinase activity profiling platforms allow for a broad assessment of protein kinase networks in complex biological systems. In conjunction with sophisticated computational modeling techniques, these profiling platforms provide datasets that inform the active state of regulatory systems in disease models and highlight potential drug targets. Taken together, system-wide profiling of protein kinase activity has become a critical component of modern molecular biology research and presents a promising avenue for drug discovery.
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Affiliation(s)
- Khaled Alganem
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA
| | - Abdul-Rizaq Hamoud
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA
| | - Justin F Creeden
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA
| | - Nicholas D Henkel
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA
| | - Ali S Imami
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA
| | - Alex W Joyce
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA
| | - William G Ryan V
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA
| | - Jacob B Rethman
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA
| | - Rammohan Shukla
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA
| | - Sinead M O'Donovan
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA
| | - Jarek Meller
- Department of Biomedical Informatics, University of Cincinnati, Cincinnati, OH, USA; Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Division of Biostatistics and Bioinformatics, Department of Environmental and Public Health Sciences, University of Cincinnati, Cincinnati, OH, USA; Department of Pharmacology and System Biology, College of Medicine, University of Cincinnati, Cincinnati, OH, USA; Department of Electrical Engineering and Computer Science, College of Engineering and Applied Sciences, University of Cincinnati, Cincinnati, OH, USA
| | - Robert McCullumsmith
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, OH, USA; Neurosciences Institute, ProMedica, Toledo, OH, USA.
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14
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Brooks GA, Osmond AD, Leija RG, Curl CC, Arevalo JA, Duong JJ, Horning MA. The blood lactate/pyruvate equilibrium affair. Am J Physiol Endocrinol Metab 2022; 322:E34-E43. [PMID: 34719944 PMCID: PMC8722269 DOI: 10.1152/ajpendo.00270.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The Lactate Shuttle hypothesis is supported by a variety of techniques including mass spectrometry analytics following infusion of carbon-labeled isotopic tracers. However, there has been controversy over whether lactate tracers measure lactate (L) or pyruvate (P) turnover. Here, we review the analytical errors, use of inappropriate tissue and animal models, failure to consider L and P pool sizes in modeling results, inappropriate tracer and blood sampling sites, and failure to anticipate roles of heart and lung parenchyma on L⇔P interactions. With support from magnetic resonance spectroscopy (MRS) and immunocytochemistry, we conclude that carbon-labeled lactate tracers can be used to quantitate lactate fluxes.
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Affiliation(s)
- George A Brooks
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Adam D Osmond
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Robert G Leija
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Casey C Curl
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Jose A Arevalo
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Justin J Duong
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
| | - Michael A Horning
- Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California
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15
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Istfan N, Hasson B, Apovian C, Meshulam T, Yu L, Anderson W, Corkey BE. Acute carbohydrate overfeeding: a redox model of insulin action and its impact on metabolic dysfunction in humans. Am J Physiol Endocrinol Metab 2021; 321:E636-E651. [PMID: 34569273 PMCID: PMC8782668 DOI: 10.1152/ajpendo.00094.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 08/23/2021] [Accepted: 09/20/2021] [Indexed: 11/22/2022]
Abstract
A role for fat overfeeding in metabolic dysfunction in humans is commonly implied in the literature. Comparatively less is known about acute carbohydrate overfeeding (COF). We tested the hypothesis that COF predisposes to oxidative stress by channeling electrons away from antioxidants to support energy storage. In a study of 24 healthy human subjects with and without obesity, COF was simulated by oral administration of excess carbohydrates; a two-step hyperinsulinemic clamp was used to evaluate insulin action. The distribution of electrons between oxidative and reductive pathways was evaluated by the changes in the reduction potentials (Eh) of cytoplasmic (lactate, pyruvate) and mitochondrial (β-hydroxybutyrate, acetoacetate) redox couples. Antioxidant redox was measured by the ratio of reduced to oxidized glutathione. We used cross-correlation analysis to evaluate the relationships between the trajectories of Eh, insulin, glucose, and respiratory exchange during COF. DDIT3 and XBP1s/u mRNA were measured as markers of endoplasmic reticulum stress (ER stress) in adipose tissue before and after COF. Here, we show that acute COF is characterized by net transfer of electrons from mitochondria to cytoplasm. Circulating glutathione is oxidized in a manner that significantly cross-correlates with increasing insulin levels and precedes the decrease in cytoplasmic Eh. This effect is more pronounced in overweight individuals (OW). Markers of ER stress in subcutaneous fat are detectable in OW within 4 h. We conclude that acute COF contributes to metabolic dysfunction through insulin-dependent pathways that promote electron transfer to the cytoplasm and decrease antioxidant capacity. Characterization of redox during overfeeding is important for understanding the pathophysiology of obesity and type 2 diabetes.NEW & NOTEWORTHY Current principles assume that conversion of thermic energy to metabolically useful energy follows fixed rules. These principles ignore the possibility of variable proton uncoupling in mitochondria. Our study shows that the net balance of electron distribution between mitochondria and cytoplasm is influenced by insulin in a manner that reduces proton leakage during overfeeding. Characterization of the effects of insulin on redox balance is important for understanding obesity and insulin resistance.
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Affiliation(s)
- Nawfal Istfan
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, Massachusetts
| | | | - Caroline Apovian
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, Massachusetts
| | - Tova Meshulam
- Section of Endocrinology, Diabetes, and Nutrition, Boston Medical Center and Boston University School of Medicine, Boston, Massachusetts
| | - Liqun Yu
- Section of Endocrinology, Diabetes, and Nutrition, Boston Medical Center and Boston University School of Medicine, Boston, Massachusetts
| | - Wendy Anderson
- Section of Endocrinology, Diabetes, and Nutrition, Boston Medical Center and Boston University School of Medicine, Boston, Massachusetts
- Section of Minimally Invasive Surgery, Boston Medical Center, Boston, Massachusetts
| | - Barbara E Corkey
- Section of Endocrinology, Diabetes, and Nutrition, Boston Medical Center and Boston University School of Medicine, Boston, Massachusetts
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16
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Abstract
The reactions of the tricarboxylic acid (TCA) cycle allow the controlled combustion of fat and carbohydrate. In principle, TCA cycle intermediates are regenerated on every turn and can facilitate the oxidation of an infinite number of nutrient molecules. However, TCA cycle intermediates can be lost to cataplerotic pathways that provide precursors for biosynthesis, and they must be replaced by anaplerotic pathways that regenerate these intermediates. Together, anaplerosis and cataplerosis help regulate rates of biosynthesis by dictating precursor supply, and they play underappreciated roles in catabolism and cellular energy status. They facilitate recycling pathways and nitrogen trafficking necessary for catabolism, and they influence redox state and oxidative capacity by altering TCA cycle intermediate concentrations. These functions vary widely by tissue and play emerging roles in disease. This article reviews the roles of anaplerosis and cataplerosis in various tissues and discusses how they alter carbon transitions, and highlights their contribution to mechanisms of disease. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Melissa Inigo
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA;
| | - Stanisław Deja
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; .,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Shawn C Burgess
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA; .,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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17
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Roussin M, Salcedo SP. NAD+-targeting by bacteria: an emerging weapon in pathogenesis. FEMS Microbiol Rev 2021; 45:6315328. [PMID: 34223888 DOI: 10.1093/femsre/fuab037] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 07/01/2021] [Indexed: 11/14/2022] Open
Abstract
Nicotinamide adenine dinucleotide (NAD+) is a major cofactor in redox reactions in all lifeforms. A stable level of NAD+ is vital to ensure cellular homeostasis. Some pathogens can modulate NAD+ metabolism to their advantage and even utilize or cleave NAD+ from the host using specialized effectors known as ADP-ribosyltransferase toxins and NADases, leading to energy store depletion, immune evasion, or even cell death. This review explores recent advances in the field of bacterial NAD+-targeting toxins, highlighting the relevance of NAD+ modulation as an emerging pathogenesis strategy. In addition, we discuss the role of specific NAD+-targeting toxins in niche colonization and bacterial lifestyle as components of Toxin/Antitoxin systems and key players in inter-bacterial competition. Understanding the mechanisms of toxicity, regulation, and secretion of these toxins will provide interesting leads in the search for new antimicrobial treatments in the fight against infectious diseases.
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Affiliation(s)
- Morgane Roussin
- Laboratory of Molecular Microbiology and Structural Biochemistry, Centre National de la Recherche Scientifique UMR5086, Université de Lyon, Lyon, France
| | - Suzana P Salcedo
- Laboratory of Molecular Microbiology and Structural Biochemistry, Centre National de la Recherche Scientifique UMR5086, Université de Lyon, Lyon, France
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18
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Stagg DB, Gillingham JR, Nelson AB, Lengfeld JE, d'Avignon DA, Puchalska P, Crawford PA. Diminished ketone interconversion, hepatic TCA cycle flux, and glucose production in D-β-hydroxybutyrate dehydrogenase hepatocyte-deficient mice. Mol Metab 2021; 53:101269. [PMID: 34116232 PMCID: PMC8259407 DOI: 10.1016/j.molmet.2021.101269] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 05/28/2021] [Accepted: 06/03/2021] [Indexed: 12/20/2022] Open
Abstract
Objective Throughout the last decade, interest has intensified in intermittent fasting, ketogenic diets, and exogenous ketone therapies as prospective health-promoting, therapeutic, and performance-enhancing agents. However, the regulatory roles of ketogenesis and ketone metabolism on liver homeostasis remain unclear. Therefore, we sought to develop a better understanding of the metabolic consequences of hepatic ketone body metabolism by focusing on the redox-dependent interconversion of acetoacetate (AcAc) and D-β-hydroxybutyrate (D-βOHB). Methods Using targeted and isotope tracing high-resolution liquid chromatography-mass spectrometry, dual stable isotope tracer nuclear magnetic resonance spectroscopy-based metabolic flux modeling, and complementary physiological approaches in novel cell type-specific knockout mice, we quantified the roles of hepatocyte D-β-hydroxybutyrate dehydrogenase (BDH1), a mitochondrial enzyme required for NAD+/NADH-dependent oxidation/reduction of ketone bodies. Results Exogenously administered AcAc is reduced to D-βOHB, which increases hepatic NAD+/NADH ratio and reflects hepatic BDH1 activity. Livers of hepatocyte-specific BDH1-deficient mice did not produce D-βOHB, but owing to extrahepatic BDH1, these mice nonetheless remained capable of AcAc/D-βOHB interconversion. Compared to littermate controls, hepatocyte-specific BDH1 deficient mice exhibited diminished liver tricarboxylic acid (TCA) cycle flux and impaired gluconeogenesis, but normal hepatic energy charge overall. Glycemic recovery after acute insulin challenge was impaired in knockout mice, but they were not more susceptible to starvation-induced hypoglycemia. Conclusions Ketone bodies influence liver homeostasis. While liver BDH1 is not required for whole body equilibration of AcAc and D-βOHB, loss of the ability to interconvert these ketone bodies in hepatocytes results in impaired TCA cycle flux and glucose production. Therefore, through oxidation/reduction of ketone bodies, BDH1 is a significant contributor to hepatic mitochondrial redox, liver physiology, and organism-wide ketone body homeostasis. Exogenously administered acetoacetate is reduced to D-β-hydroxybutyrate, increasing hepatic NAD+/NADH ratio. Liver BDH1 is not required for whole body equilibration of acetoacetate and D-β-hydroxybutyrate. Hepatocyte-specific loss of BDH1 reduces hepatic TCA cycle flux, and TCA-cycle sourced gluconeogenesis. Hepatocyte-specific loss of BDH1 impairs glycemic recovery without provoking starvation-induced hypoglycemia.
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Affiliation(s)
- David B Stagg
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, USA; Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Jacob R Gillingham
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Alisa B Nelson
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, USA; Bioinformatics and Computational Biology Program, University of Minnesota, Minneapolis, MN, USA
| | - Justin E Lengfeld
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - D André d'Avignon
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Patrycja Puchalska
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Peter A Crawford
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, USA; Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA; Bioinformatics and Computational Biology Program, University of Minnesota, Minneapolis, MN, USA.
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19
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Bhullar KS, Son M, Kerek E, Cromwell CR, Wingert BM, Wu K, Jovel J, Camacho CJ, Hubbard BP, Wu J. Tripeptide IRW Upregulates NAMPT Protein Levels in Cells and Obese C57BL/6J Mice. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:1555-1566. [PMID: 33522796 DOI: 10.1021/acs.jafc.0c07831] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nicotinamide adenine dinucleotide (NAD+) plays a vital role in cellular processes that govern human health and disease. Nicotinamide phosphoribosyltransferase (NAMPT) is a rate-limiting enzyme in NAD+ biosynthesis. Thus, boosting NAD+ level via an increase in NAMPT levels is an attractive approach for countering the effects of aging and metabolic disease. This study aimed to establish IRW (Ile-Arg-Trp), a small tripeptide derived from ovotransferrin, as a booster of NAMPT levels. Treatment of muscle (L6) cells with IRW increased intracellular NAMPT protein levels (2.2-fold, p < 0.05) and boosted NAD+ (p < 0.01). Both immunoprecipitation and recombinant NAMPT assays indicated the possible NAMPT-activating ability of IRW (p < 0.01). Similarly, IRW increased NAMPT mRNA and protein levels in the liver (2.6-fold, p < 0.01) and muscle tissues (2.3-fold, p < 0.05) of C57BL/6J mice fed with a high-fat diet (HFD). A significantly increased level of circulating NAD+ was also observed following IRW treatment (4.7 fold, p < 0.0001). Dosing of Drosophila melanogaster with IRW elevated both D-NAAM (fly NAMPT) and NAD+ in vivo (p < 0.05). However, IRW treatment did not boost NAMPT levels in SIRT1 KO cells, indicating a possible SIRT1 dependency for the pharmacological effect. Overall, these data indicate that IRW is a novel small peptide booster of the NAMPT pool.
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Affiliation(s)
- Khushwant S Bhullar
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
- Department of Pharmacology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Myoungjin Son
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Evan Kerek
- Department of Pharmacology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | | | - Bentley M Wingert
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Kaiyu Wu
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Juan Jovel
- Office of Research, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Carlos J Camacho
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Basil P Hubbard
- Department of Pharmacology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Jianping Wu
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
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20
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White H, Venkatesh B, Jones M, Kruger PS, Walsham J, Fuentes H. Inducing ketogenesis via an enteral formulation in patients with acute brain injury:a phase II study. Neurol Res 2020; 42:275-285. [PMID: 32098578 DOI: 10.1080/01616412.2019.1709743] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Objective: Although extensively studied in children, the safety and tolerability of ketone supplementation in adults is unclear, particularly in the acute brain injury population. The purpose of this study was to examine the feasibility and safety of inducing ketosis using an enteric ketogenic formulation and determine its impact on intracranial and cerebral perfusion pressures and metabolic parameters.Methods: Prospective interventional Phase II trial of ventilated critically ill patients with acute brain injury administered a ketogenic feed over a 6 day period.Results: 20 patients were recruited, 5 females and 15 males, 3 with stroke, 2 with subarachnoid haemorrhage and 15 with traumatic brain injury. Feeds were well tolerated with 19 patients completing study. There was a significant increase in both plasma beta-hydroxybutyrate and acetoacetate from 0.24± 0.31 mmol/l and 0.19 ± 0.16 mmol/l to 0.61 ± 0.53 mmol/l (p =0.0005) and 0.52 ± 0.40 mmol/l (p<0.0001) respectively over the 6 day period. Total daily Ketocal® caloric intake was positively correlated with plasma beta-hydroxybutyrate concentrations (p=0.0011). There was no significant correlation between the cerebral hypertension and cerebral hypoperfusion indices and plasma ketone concentrations. In 95% of patients there were no clinically significant changes in acid/base status over the 6 days with pH remaining within normal range.Conclusion: In patients with acute brain injury, an enterally administered ketogenic formulation increased plasma ketone concentrations, was well tolerated, did not impact on cerebral hemodynamics and can be safely administered.Clinical trial registered at the Australian New Zealand Clinical Trials Registry (ACTRN12616000332426)Abbreviations: BHB: betahydroxybutyrate; AcAc: acetoacetate; ABI: acute brain injury; TBI: traumatic brain injury; CSF: cerebrospinal fluid; SAH: subarachnoid injury; CVA: cerebrovascular accidents; ICP: intracranial pressure; CPP: cerebral perfusion pressure; ICU: intensive care unit; EVD: external ventricular device; CHI: cerebral hypoperfusion index; IHI: intracranial hypertension index; GCS: Glasgow Coma Scale.
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Affiliation(s)
- Hayden White
- Critical Care Medicine, Department of Intensive Care, Griffiths University, Logan Hospital, Logan, Australia
| | - Balasubramanian Venkatesh
- Critical Care Medicine, University of Queensland, Princess Alexandra & Wesley Hospitals, Brisbane, Australia
| | - Mark Jones
- School of Public Health, Faculty of Medicine and Biomedical Sciences, University of Queensland, Brisbane, Australia
| | - Peter S Kruger
- Critical Care Medicine, University of Queensland, Princess Alexandra Hospital, Brisbane, Australia
| | - James Walsham
- Department of intensive care medicine, Princess Alexandra Hospitals
| | - Hesly Fuentes
- Department of Intensive Care, Princess Alexandra Hospital, Brisbane, Australia
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21
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Obrador E, Liu-Smith F, Dellinger RW, Salvador R, Meyskens FL, Estrela JM. Oxidative stress and antioxidants in the pathophysiology of malignant melanoma. Biol Chem 2019; 400:589-612. [PMID: 30352021 DOI: 10.1515/hsz-2018-0327] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/09/2018] [Indexed: 02/07/2023]
Abstract
The high number of somatic mutations in the melanoma genome associated with cumulative ultra violet (UV) exposure has rendered it one of the most difficult of cancers to treat. With new treatment approaches based on targeted and immune therapies, drug resistance has appeared as a consistent problem. Redox biology, including reactive oxygen and nitrogen species (ROS and RNS), plays a central role in all aspects of melanoma pathophysiology, from initiation to progression and to metastatic cells. The involvement of melanin production and UV radiation in ROS/RNS generation has rendered the melanocytic lineage a unique system for studying redox biology. Overall, an elevated oxidative status has been associated with melanoma, thus much effort has been expended to prevent or treat melanoma using antioxidants which are expected to counteract oxidative stress. The consequence of this redox-rebalance seems to be two-fold: on the one hand, cells may behave less aggressively or even undergo apoptosis; on the other hand, cells may survive better after being disseminated into the circulating system or after drug treatment, thus resulting in metastasis promotion or further drug resistance. In this review we summarize the current understanding of redox signaling in melanoma at cellular and systemic levels and discuss the experimental and potential clinic use of antioxidants and new epigenetic redox modifiers.
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Affiliation(s)
- Elena Obrador
- Department of Phisiology, University of Valencia, 46010 Valencia, Spain
| | - Feng Liu-Smith
- Department of Epdemiology, Department of Medicine, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA 92697, USA.,Department of Medicine, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA 92697, USA
| | | | - Rosario Salvador
- Department of Phisiology, University of Valencia, 46010 Valencia, Spain
| | - Frank L Meyskens
- Department of Epdemiology, Department of Medicine, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA 92697, USA.,Department of Medicine, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA 92697, USA.,Department of Biological Chemistry, Chao Family Comprehensive Cancer Center, University of California, Irvine, CA 92697, USA
| | - José M Estrela
- Department of Phisiology, University of Valencia, 46010 Valencia, Spain
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Cappel DA, Deja S, Duarte JAG, Kucejova B, Iñigo M, Fletcher JA, Fu X, Berglund ED, Liu T, Elmquist JK, Hammer S, Mishra P, Browning JD, Burgess SC. Pyruvate-Carboxylase-Mediated Anaplerosis Promotes Antioxidant Capacity by Sustaining TCA Cycle and Redox Metabolism in Liver. Cell Metab 2019; 29:1291-1305.e8. [PMID: 31006591 PMCID: PMC6585968 DOI: 10.1016/j.cmet.2019.03.014] [Citation(s) in RCA: 117] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 01/12/2019] [Accepted: 03/26/2019] [Indexed: 01/09/2023]
Abstract
The hepatic TCA cycle supports oxidative and biosynthetic metabolism. This dual responsibility requires anaplerotic pathways, such as pyruvate carboxylase (PC), to generate TCA cycle intermediates necessary for biosynthesis without disrupting oxidative metabolism. Liver-specific PC knockout (LPCKO) mice were created to test the role of anaplerotic flux in liver metabolism. LPCKO mice have impaired hepatic anaplerosis, diminution of TCA cycle intermediates, suppressed gluconeogenesis, reduced TCA cycle flux, and a compensatory increase in ketogenesis and renal gluconeogenesis. Loss of PC depleted aspartate and compromised urea cycle function, causing elevated urea cycle intermediates and hyperammonemia. Loss of PC prevented diet-induced hyperglycemia and insulin resistance but depleted NADPH and glutathione, which exacerbated oxidative stress and correlated with elevated liver inflammation. Thus, despite catalyzing the synthesis of intermediates also produced by other anaplerotic pathways, PC is specifically necessary for maintaining oxidation, biosynthesis, and pathways distal to the TCA cycle, such as antioxidant defenses.
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Affiliation(s)
- David A Cappel
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Stanisław Deja
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - João A G Duarte
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Blanka Kucejova
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Melissa Iñigo
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Justin A Fletcher
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xiaorong Fu
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Eric D Berglund
- Center for Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Tiemin Liu
- Sate Key Laboratory of Genetic Engineering, School of Life Sciences, Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, Shanghai 200438, China
| | - Joel K Elmquist
- Center for Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Suntrea Hammer
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Prashant Mishra
- Children's Medical Center Research Institute, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jeffrey D Browning
- Department of Clinical Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Shawn C Burgess
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX, USA.
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23
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Potts A, Uchida A, Deja S, Berglund ED, Kucejova B, Duarte JA, Fu X, Browning JD, Magnuson MA, Burgess SC. Cytosolic phosphoenolpyruvate carboxykinase as a cataplerotic pathway in the small intestine. Am J Physiol Gastrointest Liver Physiol 2018; 315:G249-G258. [PMID: 29631378 PMCID: PMC6139646 DOI: 10.1152/ajpgi.00039.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cytosolic phosphoenolpyruvate carboxykinase (PEPCK) is a gluconeogenic enzyme that is highly expressed in the liver and kidney but is also expressed at lower levels in a variety of other tissues where it may play adjunct roles in fatty acid esterification, amino acid metabolism, and/or TCA cycle function. PEPCK is expressed in the enterocytes of the small intestine, but it is unclear whether it supports a gluconeogenic rate sufficient to affect glucose homeostasis. To examine potential roles of intestinal PEPCK, we generated an intestinal PEPCK knockout mouse. Deletion of intestinal PEPCK ablated ex vivo gluconeogenesis but did not significantly affect glycemia in chow, high-fat diet, or streptozotocin-treated mice. In contrast, postprandial triglyceride secretion from the intestine was attenuated in vivo, consistent with a role in fatty acid esterification. Intestinal amino acid profiles and 13C tracer appearance into these pools were significantly altered, indicating abnormal amino acid trafficking through the enterocyte. The data suggest that the predominant role of PEPCK in the small intestine of mice is not gluconeogenesis but rather to support nutrient processing, particularly with regard to lipids and amino acids. NEW & NOTEWORTHY The small intestine expresses gluconeogenic enzymes for unknown reasons. In addition to glucose synthesis, the nascent steps of this pathway can be used to support amino acid and lipid metabolisms. When phosphoenolpyruvate carboxykinase, an essential gluconeogenic enzyme, is knocked out of the small intestine of mice, glycemia is unaffected, but mice inefficiently absorb dietary lipid, have abnormal amino acid profiles, and inefficiently catabolize glutamine. Therefore, the initial steps of intestinal gluconeogenesis are used for processing dietary triglycerides and metabolizing amino acids but are not essential for maintaining blood glucose levels.
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Affiliation(s)
- Austin Potts
- 1Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Aki Uchida
- 1Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Stanislaw Deja
- 2Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Eric D. Berglund
- 1Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Blanka Kucejova
- 2Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Joao A. Duarte
- 1Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Xiaorong Fu
- 2Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jeffrey D. Browning
- 3Department of Clinical Nutrition, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Mark A. Magnuson
- 5Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Shawn C. Burgess
- 1Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas,4Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas
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Chi YC, Lee SL, Lee YP, Lai CL, Yin SJ. Modeling of Human Hepatic and Gastrointestinal Ethanol Metabolism with Kinetic-Mechanism-Based Full-Rate Equations of the Component Alcohol Dehydrogenase Isozymes and Allozymes. Chem Res Toxicol 2018; 31:556-569. [PMID: 29847918 DOI: 10.1021/acs.chemrestox.8b00003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Alcohol dehydrogenase (ADH) is the principal enzyme responsible for the metabolism of ethanol. Human ADH constitutes a complex family of isozymes and allozymes with striking variation in kinetic properties and tissue distribution. The liver and the gastrointestinal tract are the major sites for first-pass metabolism (FPM). The quantitative contributions of ADH isozymes and ethnically distinct allozymes to cellular ethanol metabolism remain poorly understood. To address this issue, kinetic mechanism and the steady-state full-rate equations for recombinant human class I ADH1A, ADH1B (including allozymes ADH1B1, ADH1B2, and ADH1B3), ADH1C (including allozymes ADH1C1 and ADH1C2), class II ADH2, and class IV ADH4 were determined by initial velocity, product inhibition, and dead-end inhibition experiments in 0.1 M sodium phosphate at pH 7.5 and 25 °C. Models of the hepatic and gastrointestinal metabolisms of ethanol were constructed by linear combination of the numerical full-rate equations of the component isozymes and allozymes in target organs. The organ simulations indicate that in homozygous ADH1B*1/*1 livers, a representative genotype among ethnically distinct populations due to high prevalence of the allele, major contributors at 1 to 10 mM ethanol are ADH1B1 (45% to 24%) and the ADH1C allozymes (54% to 40%). The simulated activities at 1 to 50 mM ethanol for the gastrointestinal tract (total mucosae of ADH1C*1/*1-ADH4 stomach and the ADH1C*1/*1-ADH2 duodenum and jejunum) account for 0.68%-0.76% of that for the ADH1B*1/*1-ADH1C*1/*1 liver, suggesting gastrointestinal tract plays a relatively minor role in the human FPM of ethanol. Based on the flow-limited sinusoidal perfusion model, the simulated hepatic Kmapp, Vmaxapp, and Ci at a 95% clearance of ethanol for ADH1B*1/*1-ADH1C*1/*1 livers are compatible to that documented in hepatic vein catheterization and pharmacokinetic studies with humans that controlled for the genotypes. The model simulations suggest that slightly higher or similar ethanol elimination rates for ADH1B*2/*2 and ADH1B*3/*3 individuals compared with those for ADH1B*1/*1 individuals may result from higher hepatocellular acetaldehyde.
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Affiliation(s)
- Yu-Chou Chi
- Department of Biochemistry , National Defense Medical Center , 161 Minchuan East Road Section 6 , Taipei 11490 , Taiwan
| | - Shou-Lun Lee
- Department of Biological Science and Technology , China Medical University , 91 Hsueh-Shih Road , Taichung 40402 , Taiwan
| | - Yung-Ping Lee
- Department of Biochemistry , National Defense Medical Center , 161 Minchuan East Road Section 6 , Taipei 11490 , Taiwan
| | - Ching-Long Lai
- Department of Nursing , Chang Gung University of Science and Technology , 261 Wenhwa First Road , Taoyuan City 33303 , Taiwan
| | - Shih-Jiun Yin
- Department of Biochemistry , National Defense Medical Center , 161 Minchuan East Road Section 6 , Taipei 11490 , Taiwan
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25
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A genetically encoded tool for manipulation of NADP +/NADPH in living cells. Nat Chem Biol 2017; 13:1088-1095. [PMID: 28805804 PMCID: PMC5605434 DOI: 10.1038/nchembio.2454] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 07/12/2017] [Indexed: 01/01/2023]
Abstract
NADH and NADPH are redox coenzymes broadly required for energy metabolism, biosynthesis and detoxification. Despite detailed knowledge of specific enzymes and pathways that utilize these coenzymes, a holistic understanding of the regulation and compartmentalization of NADH and NADPH-dependent pathways is lacking, in part because of a lack of tools with which to investigate them in living cells. We previously reported the use of the naturally occurring Lactobacillus brevis H2O-forming NADH oxidase (LbNOX) as a genetic tool for manipulation of the NAD+/NADH ratio in human cells. Here we present TPNOX (triphosphopyridine nucleotide oxidase), a rationally designed and engineered mutant of LbNOX that is strictly specific towards NADPH. We characterize the effects of TPNOX expression on cellular metabolism and use it in combination with LbNOX to show how the redox states of mitochondrial NADPH and NADH pools are connected.
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26
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Mortensen A, Aguilar F, Crebelli R, Di Domenico A, Dusemund B, Frutos MJ, Galtier P, Gott D, Gundert-Remy U, Leblanc JC, Lindtner O, Moldeus P, Mosesso P, Parent-Massin D, Oskarsson A, Stankovic I, Waalkens-Berendsen I, Woutersen RA, Wright M, Younes M, Boon P, Chrysafidis D, Gürtler R, Tobback P, Altieri A, Rincon AM, Lambré C. Re-evaluation of glutamic acid (E 620), sodium glutamate (E 621), potassium glutamate (E 622), calcium glutamate (E 623), ammonium glutamate (E 624) and magnesium glutamate (E 625) as food additives. EFSA J 2017; 15:e04910. [PMID: 32625571 PMCID: PMC7009848 DOI: 10.2903/j.efsa.2017.4910] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re-evaluating the safety of glutamic acid-glutamates (E 620-625) when used as food additives. Glutamate is absorbed in the intestine and it is presystemically metabolised in the gut wall. No adverse effects were observed in the available short-term, subchronic, chronic, reproductive and developmental studies. The only effect observed was increased kidney weight and increased spleen weight; however, the increase in organ weight was not accompanied by adverse histopathological findings and, therefore, the increase in organ weight was not considered as an adverse effect. The Panel considered that glutamic acid-glutamates (E 620-625) did not raise concern with regards to genotoxicity. From a neurodevelopmental toxicity study, a no observed adverse effect level (NOAEL) of 3,200 mg monosodium glutamate/kg body weight (bw) per day could be identified. The Panel assessed the suitability of human data to be used for the derivation of a health-based guidance value. Although effects on humans were identified human data were not suitable due to the lack of dose-response data from which a dose without effect could be identified. Based on the NOAEL of 3,200 mg monosodium glutamate/kg bw per day from the neurodevelopmental toxicity study and applying the default uncertainty factor of 100, the Panel derived a group acceptable daily intake (ADI) of 30 mg/kg bw per day, expressed as glutamic acid, for glutamic acid and glutamates (E 620-625). The Panel noted that the exposure to glutamic acid and glutamates (E 620-625) exceeded not only the proposed ADI, but also doses associated with adverse effects in humans for some population groups.
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27
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Yang Y, Sauve AA. NAD(+) metabolism: Bioenergetics, signaling and manipulation for therapy. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1864:1787-1800. [PMID: 27374990 PMCID: PMC5521000 DOI: 10.1016/j.bbapap.2016.06.014] [Citation(s) in RCA: 291] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/30/2016] [Accepted: 06/28/2016] [Indexed: 12/19/2022]
Abstract
We survey the historical development of scientific knowledge surrounding Vitamin B3, and describe the active metabolite forms of Vitamin B3, the pyridine dinucleotides NAD+ and NADP+ which are essential to cellular processes of energy metabolism, cell protection and biosynthesis. The study of NAD+ has become reinvigorated by new understandings that dynamics within NAD+ metabolism trigger major signaling processes coupled to effectors (sirtuins, PARPs, and CD38) that reprogram cellular metabolism using NAD+ as an effector substrate. Cellular adaptations include stimulation of mitochondrial biogenesis, a process fundamental to adjusting cellular and tissue physiology to reduced nutrient availability and/or increased energy demand. Several mammalian metabolic pathways converge to NAD+, including tryptophan-derived de novo pathways, nicotinamide salvage pathways, nicotinic acid salvage and nucleoside salvage pathways incorporating nicotinamide riboside and nicotinic acid riboside. Key discoveries highlight a therapeutic potential for targeting NAD+ biosynthetic pathways for treatment of human diseases. A recent emergence of understanding that NAD+ homeostasis is vulnerable to aging and disease processes has stimulated testing to determine if replenishment or augmentation of cellular or tissue NAD+ can have ameliorative effects on aging or disease phenotypes. This experimental approach has provided several proofs of concept successes demonstrating that replenishment or augmentation of NAD+ concentrations can provide ameliorative or curative benefits. Thus NAD+ metabolic pathways can provide key biomarkers and parameters for assessing and modulating organism health.
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Affiliation(s)
- Yue Yang
- Department of Pharmacology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
| | - Anthony A Sauve
- Department of Pharmacology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA.
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28
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Conley KE, Ali AS, Flores B, Jubrias SA, Shankland EG. Mitochondrial NAD(P)H In vivo: Identifying Natural Indicators of Oxidative Phosphorylation in the (31)P Magnetic Resonance Spectrum. Front Physiol 2016; 7:45. [PMID: 27065875 PMCID: PMC4812112 DOI: 10.3389/fphys.2016.00045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/01/2016] [Indexed: 01/20/2023] Open
Abstract
Natural indicators provide intrinsic probes of metabolism, biogenesis and oxidative protection. Nicotinamide adenine dinucleotide metabolites (NAD(P)) are one class of indicators that have roles as co-factors in oxidative phosphorylation, glycolysis, and anti-oxidant protection, as well as signaling in the mitochondrial biogenesis pathway. These many roles are made possible by the distinct redox states (NAD(P)(+) and NAD(P)H), which are compartmentalized between cytosol and mitochondria. Here we provide evidence for detection of NAD(P)(+) and NAD(P)H in separate mitochondrial and cytosol pools in vivo in human tissue by phosphorus magnetic resonance spectroscopy ((31)P MRS). These NAD(P) pools are identified by chemical standards (NAD(+), NADP(+), and NADH) and by physiological tests. A unique resonance reflecting mitochondrial NAD(P)H is revealed by the changes elicited by elevation of mitochondrial oxidation. The decline of NAD(P)H with oxidation is matched by a stoichiometric rise in the NAD(P)(+) peak. This unique resonance also provides a measure of the improvement in mitochondrial oxidation that parallels the greater phosphorylation found after exercise training in these elderly subjects. The implication is that the dynamics of the mitochondrial NAD(P)H peak provides an intrinsic probe of the reversal of mitochondrial dysfunction in elderly muscle. Thus, non-invasive detection of NAD(P)(+) and NAD(P)H in cytosol vs. mitochondria yields natural indicators of redox compartmentalization and sensitive intrinsic probes of the improvement of mitochondrial function with an intervention in human tissues in vivo. These natural indicators hold the promise of providing mechanistic insight into metabolism and mitochondrial function in vivo in a range of tissues in health, disease and with treatment.
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Affiliation(s)
- Kevin E Conley
- Department of Radiology, University of Washington Medical CenterSeattle, WA, USA; Department of Physiology and Biophysics, University of Washington Medical CenterSeattle, WA, USA; Department of Bioengineering, University of Washington Medical CenterSeattle, WA, USA
| | - Amir S Ali
- Department of Radiology, University of Washington Medical Center Seattle, WA, USA
| | - Brandon Flores
- Department of Radiology, University of Washington Medical Center Seattle, WA, USA
| | - Sharon A Jubrias
- Department of Radiology, University of Washington Medical Center Seattle, WA, USA
| | - Eric G Shankland
- Department of Radiology, University of Washington Medical Center Seattle, WA, USA
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29
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Estrela JM, Ortega A, Mena S, Sirerol JA, Obrador E. Glutathione in metastases: From mechanisms to clinical applications. Crit Rev Clin Lab Sci 2016; 53:253-67. [DOI: 10.3109/10408363.2015.1136259] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- José M. Estrela
- Department of Physiology, Faculty of Medicine and Odontology and
- Department of Physiology, Faculty of Pharmacy, University of Valencia, Valencia, Spain
| | - Angel Ortega
- Department of Physiology, Faculty of Pharmacy, University of Valencia, Valencia, Spain
| | - Salvador Mena
- Department of Physiology, Faculty of Pharmacy, University of Valencia, Valencia, Spain
| | - J. Antoni Sirerol
- Department of Physiology, Faculty of Pharmacy, University of Valencia, Valencia, Spain
| | - Elena Obrador
- Department of Physiology, Faculty of Medicine and Odontology and
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30
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Satapati S, Kucejova B, Duarte JAG, Fletcher JA, Reynolds L, Sunny NE, He T, Nair LA, Livingston KA, Fu X, Merritt ME, Sherry AD, Malloy CR, Shelton JM, Lambert J, Parks EJ, Corbin I, Magnuson MA, Browning JD, Burgess SC. Mitochondrial metabolism mediates oxidative stress and inflammation in fatty liver. J Clin Invest 2015; 125:4447-62. [PMID: 26571396 DOI: 10.1172/jci82204] [Citation(s) in RCA: 283] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 10/08/2015] [Indexed: 02/06/2023] Open
Abstract
Mitochondria are critical for respiration in all tissues; however, in liver, these organelles also accommodate high-capacity anaplerotic/cataplerotic pathways that are essential to gluconeogenesis and other biosynthetic activities. During nonalcoholic fatty liver disease (NAFLD), mitochondria also produce ROS that damage hepatocytes, trigger inflammation, and contribute to insulin resistance. Here, we provide several lines of evidence indicating that induction of biosynthesis through hepatic anaplerotic/cataplerotic pathways is energetically backed by elevated oxidative metabolism and hence contributes to oxidative stress and inflammation during NAFLD. First, in murine livers, elevation of fatty acid delivery not only induced oxidative metabolism, but also amplified anaplerosis/cataplerosis and caused a proportional rise in oxidative stress and inflammation. Second, loss of anaplerosis/cataplerosis via genetic knockdown of phosphoenolpyruvate carboxykinase 1 (Pck1) prevented fatty acid-induced rise in oxidative flux, oxidative stress, and inflammation. Flux appeared to be regulated by redox state, energy charge, and metabolite concentration, which may also amplify antioxidant pathways. Third, preventing elevated oxidative metabolism with metformin also normalized hepatic anaplerosis/cataplerosis and reduced markers of inflammation. Finally, independent histological grades in human NAFLD biopsies were proportional to oxidative flux. Thus, hepatic oxidative stress and inflammation are associated with elevated oxidative metabolism during an obesogenic diet, and this link may be provoked by increased work through anabolic pathways.
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31
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Lecarpentier Y, Claes V, Hébert JL, Krokidis X, Blanc FX, Michel F, Timbely O. Statistical Mechanics of the Human Placenta: A Stationary State of a Near-Equilibrium System in a Linear Regime. PLoS One 2015; 10:e0142471. [PMID: 26569482 PMCID: PMC4646433 DOI: 10.1371/journal.pone.0142471] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/22/2015] [Indexed: 11/19/2022] Open
Abstract
All near-equilibrium systems under linear regime evolve to stationary states in which there is constant entropy production rate. In an open chemical system that exchanges matter and energy with the exterior, we can identify both the energy and entropy flows associated with the exchange of matter and energy. This can be achieved by applying statistical mechanics (SM), which links the microscopic properties of a system to its bulk properties. In the case of contractile tissues such as human placenta, Huxley's equations offer a phenomenological formalism for applying SM. SM was investigated in human placental stem villi (PSV) (n = 40). PSV were stimulated by means of KCl exposure (n = 20) and tetanic electrical stimulation (n = 20). This made it possible to determine statistical entropy (S), internal energy (E), affinity (A), thermodynamic force (A / T) (T: temperature), thermodynamic flow (v) and entropy production rate (A / T x v). We found that PSV operated near equilibrium, i.e., A ≺≺ 2500 J/mol and in a stationary linear regime, i.e., (A / T) varied linearly with v. As v was dramatically low, entropy production rate which quantified irreversibility of chemical processes appeared to be the lowest ever observed in any contractile system.
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Affiliation(s)
- Yves Lecarpentier
- Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Victor Claes
- Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Jean-Louis Hébert
- Institut de Cardiologie, Hôpital de la Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Xénophon Krokidis
- Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France
| | | | - Francine Michel
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Oumar Timbely
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
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32
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Clark-Matott J, Saleem A, Dai Y, Shurubor Y, Ma X, Safdar A, Beal MF, Tarnopolsky M, Simon DK. Metabolomic analysis of exercise effects in the POLG mitochondrial DNA mutator mouse brain. Neurobiol Aging 2015; 36:2972-2983. [PMID: 26294258 DOI: 10.1016/j.neurobiolaging.2015.07.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 06/12/2015] [Accepted: 07/13/2015] [Indexed: 01/09/2023]
Abstract
Mitochondrial DNA (mtDNA) mutator mice express a mutated form of mtDNA polymerase gamma that results an accelerated accumulation of somatic mtDNA mutations in association with a premature aging phenotype. An exploratory metabolomic analysis of cortical metabolites in sedentary and exercised mtDNA mutator mice and wild-type littermate controls at 9-10 months of age was performed. Pathway analysis revealed deficits in the neurotransmitters acetylcholine, glutamate, and aspartate that were ameliorated by exercise. Nicotinamide adenine dinucleotide (NAD) depletion and evidence of increased poly(adenosine diphosphate-ribose) polymerase 1 (PARP1)activity were apparent in sedentary mtDNA mutator mouse cortex, along with deficits in carnitine metabolites and an upregulated antioxidant response that largely normalized with exercise. These data highlight specific pathways that are altered in the brain in association with an accelerated age-related accumulation of somatic mtDNA mutations. These results may have relevance to age-related neurodegenerative diseases associated with mitochondrial dysfunction, such as Alzheimer's disease and Parkinson's disease and provide insights into potential mechanisms of beneficial effects of exercise on brain function.
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Affiliation(s)
- Joanne Clark-Matott
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA.
| | - Ayesha Saleem
- Department of Pediatrics, McMaster University Medical Center, Hamilton, Ontario, Canada; Department of Medicine, McMaster University Medical Center, Hamilton, Ontario, Canada
| | - Ying Dai
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Yevgeniya Shurubor
- Brain and Mind Institute, Weill Medical College, Cornell University, New York, NY, USA
| | - Xiaoxing Ma
- Department of Pediatrics, McMaster University Medical Center, Hamilton, Ontario, Canada; Department of Medicine, McMaster University Medical Center, Hamilton, Ontario, Canada
| | - Adeel Safdar
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Myron Flint Beal
- Brain and Mind Institute, Weill Medical College, Cornell University, New York, NY, USA
| | - Mark Tarnopolsky
- Department of Pediatrics, McMaster University Medical Center, Hamilton, Ontario, Canada; Department of Medicine, McMaster University Medical Center, Hamilton, Ontario, Canada
| | - David K Simon
- Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
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33
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Cox PJ, Clarke K. Acute nutritional ketosis: implications for exercise performance and metabolism. EXTREME PHYSIOLOGY & MEDICINE 2014; 3:17. [PMID: 25379174 PMCID: PMC4212585 DOI: 10.1186/2046-7648-3-17] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/29/2014] [Indexed: 01/13/2023]
Abstract
Ketone bodies acetoacetate (AcAc) and D-β-hydroxybutyrate (βHB) may provide an alternative carbon source to fuel exercise when delivered acutely in nutritional form. The metabolic actions of ketone bodies are based on sound evolutionary principles to prolong survival during caloric deprivation. By harnessing the potential of these metabolic actions during exercise, athletic performance could be influenced, providing a useful model for the application of ketosis in therapeutic conditions. This article examines the energetic implications of ketone body utilisation with particular reference to exercise metabolism and substrate energetics.
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Affiliation(s)
- Pete J Cox
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
- Department of Cardiovascular Medicine, University of Oxford, Oxford, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
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Dedkova EN, Blatter LA. Role of β-hydroxybutyrate, its polymer poly-β-hydroxybutyrate and inorganic polyphosphate in mammalian health and disease. Front Physiol 2014; 5:260. [PMID: 25101001 PMCID: PMC4102118 DOI: 10.3389/fphys.2014.00260] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 06/19/2014] [Indexed: 12/14/2022] Open
Abstract
We provide a comprehensive review of the role of β-hydroxybutyrate (β-OHB), its linear polymer poly-β-hydroxybutyrate (PHB), and inorganic polyphosphate (polyP) in mammalian health and disease. β-OHB is a metabolic intermediate that constitutes 70% of ketone bodies produced during ketosis. Although ketosis has been generally considered as an unfavorable pathological state (e.g., diabetic ketoacidosis in type-1 diabetes mellitus), it has been suggested that induction of mild hyperketonemia may have certain therapeutic benefits. β-OHB is synthesized in the liver from acetyl-CoA by β-OHB dehydrogenase and can be used as alternative energy source. Elevated levels of PHB are associated with pathological states. In humans, short-chain, complexed PHB (cPHB) is found in a wide variety of tissues and in atherosclerotic plaques. Plasma cPHB concentrations correlate strongly with atherogenic lipid profiles, and PHB tissue levels are elevated in type-1 diabetic animals. However, little is known about mechanisms of PHB action especially in the heart. In contrast to β-OHB, PHB is a water-insoluble, amphiphilic polymer that has high intrinsic viscosity and salt-solvating properties. cPHB can form non-specific ion channels in planar lipid bilayers and liposomes. PHB can form complexes with polyP and Ca(2+) which increases membrane permeability. The biological roles played by polyP, a ubiquitous phosphate polymer with ATP-like bonds, have been most extensively studied in prokaryotes, however polyP has recently been linked to a variety of functions in mammalian cells, including blood coagulation, regulation of enzyme activity in cancer cells, cell proliferation, apoptosis and mitochondrial ion transport and energy metabolism. Recent evidence suggests that polyP is a potent activator of the mitochondrial permeability transition pore in cardiomyocytes and may represent a hitherto unrecognized key structural and functional component of the mitochondrial membrane system.
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Affiliation(s)
- Elena N Dedkova
- Department of Molecular Biophysics and Physiology, Rush University Medical Center Chicago, IL, USA
| | - Lothar A Blatter
- Department of Molecular Biophysics and Physiology, Rush University Medical Center Chicago, IL, USA
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Imai SI, Guarente L. NAD+ and sirtuins in aging and disease. Trends Cell Biol 2014; 24:464-71. [PMID: 24786309 DOI: 10.1016/j.tcb.2014.04.002] [Citation(s) in RCA: 890] [Impact Index Per Article: 89.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 03/31/2014] [Accepted: 04/01/2014] [Indexed: 02/06/2023]
Abstract
Nicotinamide adenine dinucleotide (NAD(+)) is a classical coenzyme mediating many redox reactions. NAD(+) also plays an important role in the regulation of NAD(+)-consuming enzymes, including sirtuins, poly-ADP-ribose polymerases (PARPs), and CD38/157 ectoenzymes. NAD(+) biosynthesis, particularly mediated by nicotinamide phosphoribosyltransferase (NAMPT), and SIRT1 function together to regulate metabolism and circadian rhythm. NAD(+) levels decline during the aging process and may be an Achilles' heel, causing defects in nuclear and mitochondrial functions and resulting in many age-associated pathologies. Restoring NAD(+) by supplementing NAD(+) intermediates can dramatically ameliorate these age-associated functional defects, counteracting many diseases of aging, including neurodegenerative diseases. Thus, the combination of sirtuin activation and NAD(+) intermediate supplementation may be an effective antiaging intervention, providing hope to aging societies worldwide.
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Affiliation(s)
- Shin-ichiro Imai
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Leonard Guarente
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Glenn Laboratory for the Science of Aging, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Roquet N, Lu TK. Digital and analog gene circuits for biotechnology. Biotechnol J 2014; 9:597-608. [PMID: 24677719 DOI: 10.1002/biot.201300258] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/05/2013] [Accepted: 01/08/2014] [Indexed: 11/08/2022]
Abstract
Biotechnology offers the promise of valuable chemical production via microbial processing of renewable and inexpensive substrates. Thus far, static metabolic engineering strategies have enabled this field to advance industrial applications. However, the industrial scaling of statically engineered microbes inevitably creates inefficiencies due to variable conditions present in large-scale microbial cultures. Synthetic gene circuits that dynamically sense and regulate different molecules can resolve this issue by enabling cells to continuously adapt to variable conditions. These circuits also have the potential to enable next-generation production programs capable of autonomous transitioning between steps in a bioprocess. Here, we review the design and application of two main classes of dynamic gene circuits, digital and analog, for biotechnology. Within the context of these classes, we also discuss the potential benefits of digital-analog interconversion, memory, and multi-signal integration. Though synthetic gene circuits have largely been applied for cellular computation to date, we envision that utilizing them in biotechnology will enhance the efficiency and scope of biochemical production with living cells.
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Affiliation(s)
- Nathaniel Roquet
- Synthetic Biology Group, Research Lab of Electronics, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA; Harvard Biophysics Program, Boston, MA, USA
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Rider OJ, Cox P, Tyler D, Clarke K, Neubauer S. Myocardial substrate metabolism in obesity. Int J Obes (Lond) 2013; 37:972-9. [PMID: 23069666 DOI: 10.1038/ijo.2012.170] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 08/29/2012] [Accepted: 09/02/2012] [Indexed: 12/28/2022]
Abstract
Obesity is linked to a wide variety of cardiac changes, from subclinical diastolic dysfunction to end-stage systolic heart failure. Obesity causes changes in cardiac metabolism, which make ATP production and utilization less efficient, producing functional consequences that are linked to the increased rate of heart failure in this population. As a result of the increases in circulating fatty acids and insulin resistance that accompanies excess fat storage, several of the proteins and genes that are responsible for fatty acid uptake and metabolism are upregulated, and the metabolic machinery responsible for glucose utilization and oxidation are inhibited. The resultant increase in fatty acid metabolism, and the inherent alterations in the proteins of the electron transport chain used to create the gradient needed to drive mitochondrial ATP production, results in a decrease in efficiency of cardiac work and a relative increase in oxygen usage. These changes in cardiac mitochondrial metabolism are potential therapeutic targets for the treatment and prevention of obesity-related heart failure.
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Affiliation(s)
- O J Rider
- Department of Cardiovascular Medicine, Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, John Radcliffe Hospital, Oxford, UK
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Effects of a glucokinase activator on hepatic intermediary metabolism: study with 13C-isotopomer-based metabolomics. Biochem J 2012; 444:537-51. [PMID: 22448977 DOI: 10.1042/bj20120163] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
GKAs (glucokinase activators) are promising agents for the therapy of Type 2 diabetes, but little is known about their effects on hepatic intermediary metabolism. We monitored the fate of (13)C-labelled glucose in both a liver perfusion system and isolated hepatocytes. MS and NMR spectroscopy were deployed to measure isotopic enrichment. The results demonstrate that the stimulation of glycolysis by GKA led to numerous changes in hepatic metabolism: (i) augmented flux through the TCA (tricarboxylic acid) cycle, as evidenced by greater incorporation of (13)C into the cycle (anaplerosis) and increased generation of (13)C isotopomers of citrate, glutamate and aspartate (cataplerosis); (ii) lowering of hepatic [Pi] and elevated [ATP], denoting greater phosphorylation potential and energy state; (iii) stimulation of glycogen synthesis from glucose, but inhibition of glycogen synthesis from 3-carbon precursors; (iv) increased synthesis of N-acetylglutamate and consequently augmented ureagenesis; (v) increased synthesis of glutamine, alanine, serine and glycine; and (vi) increased production and outflow of lactate. The present study provides a deeper insight into the hepatic actions of GKAs and uncovers the potential benefits and risks of GKA for treatment of diabetes. GKA improved hepatic bioenergetics, ureagenesis and glycogenesis, but decreased gluconeogenesis with a potential risk of lactic acidosis and fatty liver.
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Wagner GR, Pride PM, Babbey CM, Payne RM. Friedreich's ataxia reveals a mechanism for coordinate regulation of oxidative metabolism via feedback inhibition of the SIRT3 deacetylase. Hum Mol Genet 2012; 21:2688-97. [PMID: 22394676 PMCID: PMC3363336 DOI: 10.1093/hmg/dds095] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 02/13/2012] [Accepted: 03/01/2012] [Indexed: 12/13/2022] Open
Abstract
Friedreich's ataxia (FRDA) is the most common inherited human ataxia and is caused by a deficiency in the mitochondrial protein frataxin. Clinically, patients suffer from progressive spinocerebellar degeneration, diabetes and a fatal cardiomyopathy, associated with mitochondrial respiratory chain defects. Recent findings have shown that lysine acetylation regulates mitochondrial function and intermediary metabolism. However, little is known about lysine acetylation in the setting of pathologic energy stress and mitochondrial dysfunction. We tested the hypothesis that the respiratory chain defects in frataxin deficiency alter mitochondrial protein acetylation. Using two conditional mouse models of FRDA, we demonstrate marked hyperacetylation of numerous cardiac mitochondrial proteins. Importantly, this biochemical phenotype develops concurrently with cardiac hypertrophy and is caused by inhibition of the NAD(+)-dependent SIRT3 deacetylase. This inhibition is caused by an 85-fold decrease in mitochondrial NAD(+)/NADH and direct carbonyl group modification of SIRT3, and is reversed with excess SIRT3 and NAD(+) in vitro. We further demonstrate that protein hyperacetylation may be a common feature of mitochondrial disorders caused by respiratory chain defects, notably, cytochrome oxidase I (COI) deficiency. These findings suggest that SIRT3 inhibition and consequent protein hyperacetylation represents a negative feedback mechanism limiting mitochondrial oxidative pathways when respiratory metabolism is compromised, and thus, may contribute to the lethal cardiomyopathy in FRDA.
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Affiliation(s)
| | - P. Melanie Pride
- Department of Pediatrics, Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Clifford M. Babbey
- Department of Pediatrics, Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - R. Mark Payne
- Department of Medical and Molecular Genetics and
- Department of Pediatrics, Riley Heart Research Center, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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White H, Venkatesh B. Clinical review: ketones and brain injury. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2011; 15:219. [PMID: 21489321 PMCID: PMC3219306 DOI: 10.1186/cc10020] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Although much feared by clinicians, the ability to produce ketones has allowed humans to withstand prolonged periods of starvation. At such times, ketones can supply up to 50% of basal energy requirements. More interesting, however, is the fact that ketones can provide as much as 70% of the brain's energy needs, more efficiently than glucose. Studies suggest that during times of acute brain injury, cerebral uptake of ketones increases significantly. Researchers have thus attempted to attenuate the effects of cerebral injury by administering ketones exogenously. Hypertonic saline is commonly utilized for management of intracranial hypertension following cerebral injury. A solution containing both hypertonic saline and ketones may prove ideal for managing the dual problems of refractory intracranial hypertension and low cerebral energy levels. The purpose of the present review is to explore the physiology of ketone body utilization by the brain in health and in a variety of neurological conditions, and to discuss the potential for ketone supplementation as a therapeutic option in traumatic brain injury.
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Affiliation(s)
- Hayden White
- Department of Intensive Care, Griffi ths University, Logan Hospital, Meadowbrook, Queensland 4131, Australia.
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Bergman C, Kashiwaya Y, Veech RL. The effect of pH and free Mg2+ on ATP linked enzymes and the calculation of Gibbs free energy of ATP hydrolysis. J Phys Chem B 2010; 114:16137-46. [PMID: 20866109 DOI: 10.1021/jp105723r] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The apparent equilibrium constants, K′, of biochemical reactions containing substrates which bind [Mg2+] unequally can be significantly altered by changes in free intracellular [Mg2+]. Intracellular free [Mg2+] can be estimated by measurements of [citrate]/[isocitrate], a ratio known to vary with tissue free [Mg2+]. The combined equilibrium constant for glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and triose phosphate isomerase for the three reactions (K(GG-TPI)′) was corrected using new binding constants for dihydroxyacetone-phosphate and 3-phosphoglycerate. The result of this calculation is demonstrated in the calculation of the free energy of ATP hydrolysis. In addition, the dependence of the equilibrium constant for the glutamine synthetase reaction on pH and free [Mg2+] was demonstrated. Furthermore, a theory linking the ΔG′ value of mitochondrial complex I−II and the cytosolic ΔG′ value of ATP hydrolysis is discussed with evidence from previous publications.
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Affiliation(s)
- Christian Bergman
- Laboratory of Metabolic Control, NIAAA, NIH, DHHS, 5625 Fishers Lane, Bethesda, Maryland 20892, USA
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43
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Hasegawa H, Nakamura K. Tryptophan Hydroxylase and Serotonin Synthesis Regulation. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/s1569-7339(10)70078-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Abstract
Glutamate concentrations in plasma are 50-100 micromol/L; in whole brain, they are 10,000-12,000 micromol/L but only 0.5-2 micromol/L in extracellular fluids (ECFs). The low ECF concentrations, which are essential for optimal brain function, are maintained by neurons, astrocytes, and the blood-brain barrier (BBB). Cerebral capillary endothelial cells form the BBB that surrounds the entire central nervous system. Tight junctions connect endothelial cells and separate the BBB into luminal and abluminal domains. Molecules entering or leaving the brain thus must pass 2 membranes, and each membrane has distinct properties. Facilitative carriers exist only in luminal membranes, and Na(+)-dependent glutamate cotransporters (excitatory amino acid transporters; EAATs) exist exclusively in abluminal membranes. The EAATs are secondary transporters that couple the Na(+) gradient between the ECF and the endothelial cell to move glutamate against the existing electrochemical gradient. Thus, the EAATs in the abluminal membrane shift glutamate from the ECF to the endothelial cell where glutamate is free to diffuse into blood on facilitative carriers. This organization does not allow net glutamate entry to the brain; rather, it promotes the removal of glutamate and the maintenance of low glutamate concentrations in the ECF. This explains studies that show that the BBB is impermeable to glutamate, even at high concentrations, except in a few small areas that have fenestrated capillaries (circumventricular organs). Recently, the question of whether the BBB becomes permeable in diabetes has arisen. This issue was tested in rats with diet-induced obesity and insulin resistance or with streptozotocin-induced diabetes. Neither condition produced any detectable effect on BBB glutamate transport.
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Affiliation(s)
- Richard A Hawkins
- Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064-3095, USA.
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Bongard RD, Lindemer BJ, Krenz GS, Merker MP. Preferential utilization of NADPH as the endogenous electron donor for NAD(P)H:quinone oxidoreductase 1 (NQO1) in intact pulmonary arterial endothelial cells. Free Radic Biol Med 2009; 46:25-32. [PMID: 18848878 PMCID: PMC2638208 DOI: 10.1016/j.freeradbiomed.2008.09.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/05/2008] [Accepted: 09/10/2008] [Indexed: 11/23/2022]
Abstract
The goal was to determine whether endogenous cytosolic NAD(P)H:quinone oxidoreductase 1 (NQO1) preferentially uses NADPH or NADH in intact pulmonary arterial endothelial cells in culture. The approach was to manipulate the redox status of the NADH/NAD(+) and NADPH/NADP(+) redox pairs in the cytosolic compartment using treatment conditions targeting glycolysis and the pentose phosphate pathway alone or with lactate, and to evaluate the impact on the intact cell NQO1 activity. Cells were treated with 2-deoxyglucose, iodoacetate, or epiandrosterone in the absence or presence of lactate, NQO1 activity was measured in intact cells using duroquinone as the electron acceptor, and pyridine nucleotide redox status was measured in total cell KOH extracts by high-performance liquid chromatography. 2-Deoxyglucose decreased NADH/NAD(+) and NADPH/NADP(+) ratios by 59 and 50%, respectively, and intact cell NQO1 activity by 74%; lactate restored NADH/NAD(+), but not NADPH/NADP(+) or NQO1 activity. Iodoacetate decreased NADH/NAD(+) but had no detectable effect on NADPH/NADP(+) or NQO1 activity. Epiandrosterone decreased NQO1 activity by 67%, and although epiandrosterone alone did not alter the NADPH/NADP(+) or NADH/NAD(+) ratio, when the NQO1 electron acceptor duroquinone was also present, NADPH/NADP(+) decreased by 84% with no impact on NADH/NAD(+). Duroquinone alone also decreased NADPH/NADP(+) but not NADH/NAD(+). The results suggest that NQO1 activity is more tightly coupled to the redox status of the NADPH/NADP(+) than NADH/NAD(+) redox pair, and that NADPH is the endogenous NQO1 electron donor. Parallel studies of pulmonary endothelial transplasma membrane electron transport (TPMET), another redox process that draws reducing equivalents from the cytosol, confirmed previous observations of a correlation with the NADH/NAD(+) ratio.
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Affiliation(s)
- Robert D Bongard
- Department of Pulmonary Medicine, Medical College of Wisconsin, Milwaukee, USA
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Nissim I, Horyn O, Nissim I, Daikhin Y, Wehrli SL, Yudkoff M. 3-isobutylmethylxanthine inhibits hepatic urea synthesis: protection by agmatine. J Biol Chem 2008; 283:15063-71. [PMID: 18375388 PMCID: PMC2397462 DOI: 10.1074/jbc.m800163200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 03/27/2008] [Indexed: 11/06/2022] Open
Abstract
We previously showed that agmatine stimulated hepatic ureagenesis. In this study, we sought to determine whether the action of agmatine is mediated via cAMP signaling. A pilot experiment demonstrated that the phosphodiesterase inhibitor, 3-isobutylmethylxanthine (IBMX), inhibited urea synthesis albeit increased [cAMP]. Thus, we hypothesized that IBMX inhibits hepatic urea synthesis independent of [cAMP]. We further theorized that agmatine would negate the IBMX action and improve ureagenesis. Experiments were carried out with isolated mitochondria and (15)NH(4)Cl to trace [(15)N]citrulline production or [5-(15)N]glutamine and a rat liver perfusion system to trace ureagenesis. The results demonstrate that IBMX induced the following: (i) inhibition of the mitochondrial respiratory chain and diminished O(2) consumption during liver perfusion; (ii) depletion of the phosphorylation potential and overall hepatic energetic capacity; (iii) inhibition of [(15)N]citrulline synthesis; and (iv) inhibition of urea output in liver perfusion with little effect on [N-acetylglutamate]. The results indicate that IBMX directly and specifically inhibited complex I of the respiratory chain and carbamoyl-phosphate synthase-I (CPS-I), with an EC(50) about 0.6 mm despite a significant elevation of hepatic [cAMP]. Perfusion of agmatine with IBMX stimulated O(2) consumption, restored hepatic phosphorylation potential, and significantly stimulated ureagenesis. The action of agmatine may signify a cascade effect initiated by increased oxidative phosphorylation and greater ATP synthesis. In addition, agmatine may prevent IBMX from binding to one or more active site(s) of CPS-I and thus protect against inhibition of CPS-I. Together, the data may suggest a new experimental application of IBMX in studies of CPS-I malfunction and the use of agmatine as intervention therapy.
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Affiliation(s)
- Itzhak Nissim
- Children's Hospital of Philadelphia, Division of Child Development, Department of Pediatrics, University of Pennsylvania School of Medicine, 34th Street and Civic Center Boulevard, Philadelphia, PA 19104, USA
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Civitarese AE, Carling S, Heilbronn LK, Hulver MH, Ukropcova B, Deutsch WA, Smith SR, Ravussin E. Calorie restriction increases muscle mitochondrial biogenesis in healthy humans. PLoS Med 2007; 4:e76. [PMID: 17341128 PMCID: PMC1808482 DOI: 10.1371/journal.pmed.0040076] [Citation(s) in RCA: 539] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 01/04/2007] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Caloric restriction without malnutrition extends life span in a range of organisms including insects and mammals and lowers free radical production by the mitochondria. However, the mechanism responsible for this adaptation are poorly understood. METHODS AND FINDINGS The current study was undertaken to examine muscle mitochondrial bioenergetics in response to caloric restriction alone or in combination with exercise in 36 young (36.8 +/- 1.0 y), overweight (body mass index, 27.8 +/- 0.7 kg/m(2)) individuals randomized into one of three groups for a 6-mo intervention: Control, 100% of energy requirements; CR, 25% caloric restriction; and CREX, caloric restriction with exercise (CREX), 12.5% CR + 12.5% increased energy expenditure (EE). In the controls, 24-h EE was unchanged, but in CR and CREX it was significantly reduced from baseline even after adjustment for the loss of metabolic mass (CR, -135 +/- 42 kcal/d, p = 0.002 and CREX, -117 +/- 52 kcal/d, p = 0.008). Participants in the CR and CREX groups had increased expression of genes encoding proteins involved in mitochondrial function such as PPARGC1A, TFAM, eNOS, SIRT1, and PARL (all, p < 0.05). In parallel, mitochondrial DNA content increased by 35% +/- 5% in the CR group (p = 0.005) and 21% +/- 4% in the CREX group (p < 0.004), with no change in the control group (2% +/- 2%). However, the activity of key mitochondrial enzymes of the TCA (tricarboxylic acid) cycle (citrate synthase), beta-oxidation (beta-hydroxyacyl-CoA dehydrogenase), and electron transport chain (cytochrome C oxidase II) was unchanged. DNA damage was reduced from baseline in the CR (-0.56 +/- 0.11 arbitrary units, p = 0.003) and CREX (-0.45 +/- 0.12 arbitrary units, p = 0.011), but not in the controls. In primary cultures of human myotubes, a nitric oxide donor (mimicking eNOS signaling) induced mitochondrial biogenesis but failed to induce SIRT1 protein expression, suggesting that additional factors may regulate SIRT1 content during CR. CONCLUSIONS The observed increase in muscle mitochondrial DNA in association with a decrease in whole body oxygen consumption and DNA damage suggests that caloric restriction improves mitochondrial function in young non-obese adults.
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Affiliation(s)
- Anthony E Civitarese
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America.
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Abstracts. Free Radic Res 2007; 41 Suppl 1:6-62. [PMID: 17886027 DOI: 10.1080/10715760701615118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Nissim I, Horyn O, Daikhin Y, Nissim I, Luhovyy B, Phillips PC, Yudkoff M. Ifosfamide-induced nephrotoxicity: mechanism and prevention. Cancer Res 2006; 66:7824-31. [PMID: 16885387 DOI: 10.1158/0008-5472.can-06-1043] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The efficacy of ifosfamide (IFO), an antineoplastic drug, is severely limited by a high incidence of nephrotoxicity of unknown etiology. We hypothesized that inhibition of complex I (C-I) by chloroacetaldehyde (CAA), a metabolite of IFO, is the chief cause of nephrotoxicity, and that agmatine (AGM), which we found to augment mitochondrial oxidative phosphorylation and beta-oxidation, would prevent nephrotoxicity. Our model system was isolated mitochondria obtained from the kidney cortex of rats treated with IFO or IFO + AGM. Oxidative phosphorylation was determined with electron donors specific to complexes I, II, III, or IV (C-I, C-II, C-III, or C-IV, respectively). A parallel study was done with (13)C-labeled pyruvate to assess metabolic dysfunction. Ifosfamide treatment significantly inhibited oxidative phosphorylation with only C-I substrates. Inhibition of C-I was associated with a significant elevation of [NADH], depletion of [NAD], and decreased flux through pyruvate dehydrogenase and the TCA cycle. However, administration of AGM with IFO increased [cyclic AMP (cAMP)] and prevented IFO-induced inhibition of C-I. In vitro studies with various metabolites of IFO showed that only CAA inhibited C-I, even with supplementation with 2-mercaptoethane sulfonic acid. Following IFO treatment daily for 5 days with 50 mg/kg, the level of CAA in the renal cortex was approximately 15 micromol/L. Taken together, these observations support the hypothesis that CAA is accumulated in renal cortex and is responsible for nephrotoxicity. AGM may be protective by increasing tissue [cAMP], which phosphorylates NADH:oxidoreductase. The current findings may have an important implication for the prevention of IFO-induced nephrotoxicity and/or mitochondrial diseases secondary to defective C-I.
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Affiliation(s)
- Itzhak Nissim
- Children's Hospital of Philadelphia, Division of Child Development, Rehabilitation Medicine and Metabolic Disease, Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
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May JM, Qu ZC, Nelson DJ. Cellular disulfide-reducing capacity: an integrated measure of cell redox capacity. Biochem Biophys Res Commun 2006; 344:1352-9. [PMID: 16650819 DOI: 10.1016/j.bbrc.2006.04.065] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2006] [Accepted: 04/08/2006] [Indexed: 11/17/2022]
Abstract
To assess the disulfide reduction capacity of intact cells, EA.hy926 endothelial cells were incubated with alpha-lipoic acid in the presence of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). Alpha-lipoic acid was reduced within cells to dihydrolipoic acid, which could be quantified upon efflux from the cells as reduction of DTNB. Uptake of both alpha-lipoic acid and alpha-lipoamide occurred at least in part via a medium chain fatty acid transporter, based on inhibition by octanoate. Alpha-lipoic acid was reduced within cells by pyridine nucleotide-disulfide oxidoreductases, since it is not reduced by GSH and since its reduction was inhibited by carmustine. Nonetheless, reduction was also dependent on the cellular redox environment, since it was inhibited by the redox cycling of menadione, by decreasing intracellular GSH, and by reduction of dehydroascorbate. Together, these results show that alpha-lipoic acid-dependent DTNB reduction provides a simple method to assess the disulfide-reducing capacity of intact cells, especially as determined by pyridine nucleotide-disulfide oxidoreductases.
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Affiliation(s)
- James M May
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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