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Rahim M, Hasenour CM, Bednarski TK, Hughey CC, Wasserman DH, Young JD. Multitissue 2H/13C flux analysis reveals reciprocal upregulation of renal gluconeogenesis in hepatic PEPCK-C-knockout mice. JCI Insight 2021; 6:e149278. [PMID: 34156032 PMCID: PMC8262479 DOI: 10.1172/jci.insight.149278] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The liver is the major source of glucose production during fasting under normal physiological conditions. However, the kidney may also contribute to maintaining glucose homeostasis in certain circumstances. To test the ability of the kidney to compensate for impaired hepatic glucose production in vivo, we developed a stable isotope approach to simultaneously quantify gluconeogenic and oxidative metabolic fluxes in the liver and kidney. Hepatic gluconeogenesis from phosphoenolpyruvate was disrupted via liver-specific knockout of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C; KO). 2H/13C isotopes were infused in fasted KO and WT littermate mice, and fluxes were estimated from isotopic measurements of tissue and plasma metabolites using a multicompartment metabolic model. Hepatic gluconeogenesis and glucose production were reduced in KO mice, yet whole-body glucose production and arterial glucose were unaffected. Glucose homeostasis was maintained by a compensatory rise in renal glucose production and gluconeogenesis. Renal oxidative metabolic fluxes of KO mice increased to sustain the energetic and metabolic demands of elevated gluconeogenesis. These results show the reciprocity of the liver and kidney in maintaining glucose homeostasis by coordinated regulation of gluconeogenic flux through PEPCK-C. Combining stable isotopes with mathematical modeling provides a versatile platform to assess multitissue metabolism in various genetic, pathophysiological, physiological, and pharmacological settings.
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Affiliation(s)
- Mohsin Rahim
- Department of Chemical and Biomolecular Engineering and
| | | | | | - Curtis C Hughey
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Jamey D Young
- Department of Chemical and Biomolecular Engineering and.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
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102
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Alger JR, Minhajuddin A, Dean Sherry A, Malloy CR. Analysis of steady-state carbon tracer experiments using akaike information criteria. Metabolomics 2021; 17:61. [PMID: 34148138 DOI: 10.1007/s11306-021-01807-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/29/2021] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Carbon isotope tracers have been used to determine relative rates of tricarboxylic acid cycle (TCA) cycle pathways since the 1950s. Steady-state experimental data are typically fit to a single mathematical model of metabolism to determine metabolic fluxes. Whether the chosen model is appropriate for the biological system has generally not been evaluated systematically. An overly-simple model omits known pathways while an overly-complex model may produce incorrect results due to overfitting. OBJECTIVES The objectives were to develop and study a method that systematically evaluates multiple TCA cycle mathematical models as part of the fitting process. METHODS The problem of choosing overly-simple or overly-complex models was approached by developing software that automatically explores all possible combinations of flux through pyruvate dehydrogenase, pyruvate kinase, pyruvate carboxylase and anaplerosis at propionyl-CoA carboxylase, and equivalent pathways, all relative to TCA cycle flux. Typical TCA cycle metabolic tracer experiments that use 13C nuclear magnetic resonance for detection and quantification of 13C-enriched glutamate products were simulated and analyzed. By evaluating the multiple model fits with both the conventional sum-of-squares residual error (SSRE) and the Akaike Information Criterion (AIC), the software helps the investigator understand the interaction between model complexity and goodness of fit. RESULTS When fitting alternative models of the TCA cycle metabolism, the SSRE may identify more than one model that fits the data well. Among those models, the AIC provides guidance as to which is the simplest of the candidate models is sufficient to describe the observed data. However under some conditions, AIC used alone inappropriately discriminates against necessary metabolic complexity. CONCLUSION In combination, the SSRE and AIC help the investigator identify the model that best describes the metabolism of a biological system.
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Affiliation(s)
- Jeffry R Alger
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- NeuroSpectroScopics LLC, Sherman Oaks, CA, USA.
- Department of Neurology, Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
- Hura Imaging Inc, Calabasas, CA, USA.
| | - Abu Minhajuddin
- Department of Population and Data Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - A Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Chemistry, University of Texas at Dallas, Richardson, TX, USA
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Veterans Affairs North Texas Healthcare System, Dallas, TX, USA
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103
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You X, Tian J, Zhang H, Guo Y, Yang J, Zhu C, Song M, Wang P, Liu Z, Cancilla J, Lu W, Glorieux C, Wen S, Du H, Huang P, Hu Y. Loss of mitochondrial aconitase promotes colorectal cancer progression via SCD1-mediated lipid remodeling. Mol Metab 2021; 48:101203. [PMID: 33676027 PMCID: PMC8042449 DOI: 10.1016/j.molmet.2021.101203] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 02/27/2021] [Accepted: 02/27/2021] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVE Mitochondrial aconitase (ACO2) is an essential enzyme that bridges the TCA cycle and lipid metabolism. However, its role in cancer development remains to be elucidated. The metabolic subtype of colorectal cancer (CRC) was recently established. We investigated ACO2's potential role in CRC progression through mediating metabolic alterations. METHODS We compared the mRNA and protein expression of ACO2 between paired CRC and non-tumor tissues from 353 patients. Correlations between ACO2 levels and clinicopathological features were examined. CRC cell lines with knockdown or overexpression of ACO2 were analyzed for cell proliferation and tumor growth. Metabolomics and stable isotope tracing analyses were used to study the metabolic alterations induced by loss of ACO2. RESULTS ACO2 decreased in >50% of CRC samples compared with matched non-tumor tissues. Decreased ACO2 levels correlated with advanced disease stage (P < 0.001) and shorter patient survival (P < 0.001). Knockdown of ACO2 in CRC cells promoted cell proliferation and tumor formation, while ectopic expression of ACO2 restrained tumor growth. Specifically, blockade of ACO2 caused a reduction in TCA cycle intermediates and suppression of mitochondrial oxidative phosphorylation, resulting in an increase in glycolysis and elevated citrate flux for fatty acid and lipid synthesis. Increased citrate flux induced upregulation of stearoyl-CoA desaturase (SCD1), which enhanced lipid desaturation in ACO2-deficent cells to favor colorectal cancer growth. Pharmacological inhibition of SCD selectively reduced tumor formation of CRC with ACO2 deficiency. CONCLUSIONS Our study demonstrated that the rewiring metabolic pathway maintains CRC survival during compromised TCA cycles and characterized the therapeutic vulnerability of lipid desaturation in a meaningful subset of CRC with mitochondrial dysfunction.
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Affiliation(s)
- Xin You
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China; Department of Oncology, Molecular Oncology Research Institute, The First Affiliated Hospital of Fujian Medical University, Fuzhou 350005, Fujian, China
| | - Jingyu Tian
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China; Sun Yat-sen University Metabolomics Center, Guangzhou, Guangdong, 510080, China
| | - Hui Zhang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China; Sun Yat-sen University Metabolomics Center, Guangzhou, Guangdong, 510080, China
| | - Yunhua Guo
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China; Sun Yat-sen University Metabolomics Center, Guangzhou, Guangdong, 510080, China
| | - Jing Yang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China
| | - Chaofeng Zhu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China
| | - Ming Song
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China
| | - Peng Wang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China
| | - Zexian Liu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China
| | | | - Wenhua Lu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China; Sun Yat-sen University Metabolomics Center, Guangzhou, Guangdong, 510080, China
| | - Christophe Glorieux
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China
| | - Shijun Wen
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China
| | - Hongli Du
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou, Guangdong, 510006, China
| | - Peng Huang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China; Sun Yat-sen University Metabolomics Center, Guangzhou, Guangdong, 510080, China
| | - Yumin Hu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, 510060, China; Sun Yat-sen University Metabolomics Center, Guangzhou, Guangdong, 510080, China.
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104
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Xu Y, Fu X, Sharkey TD, Shachar-Hill Y, Walker ABJ. The metabolic origins of non-photorespiratory CO2 release during photosynthesis: a metabolic flux analysis. PLANT PHYSIOLOGY 2021; 186:297-314. [PMID: 33591309 PMCID: PMC8154043 DOI: 10.1093/plphys/kiab076] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 01/16/2021] [Indexed: 05/02/2023]
Abstract
Respiration in the light (RL) releases CO2 in photosynthesizing leaves and is a phenomenon that occurs independently from photorespiration. Since RL lowers net carbon fixation, understanding RL could help improve plant carbon-use efficiency and models of crop photosynthesis. Although RL was identified more than 75 years ago, its biochemical mechanisms remain unclear. To identify reactions contributing to RL, we mapped metabolic fluxes in photosynthesizing source leaves of the oilseed crop and model plant camelina (Camelina sativa). We performed a flux analysis using isotopic labeling patterns of central metabolites during 13CO2 labeling time course, gas exchange, and carbohydrate production rate experiments. To quantify the contributions of multiple potential CO2 sources with statistical and biological confidence, we increased the number of metabolites measured and reduced biological and technical heterogeneity by using single mature source leaves and quickly quenching metabolism by directly injecting liquid N2; we then compared the goodness-of-fit between these data and data from models with alternative metabolic network structures and constraints. Our analysis predicted that RL releases 5.2 μmol CO2 g-1 FW h-1 of CO2, which is relatively consistent with a value of 9.3 μmol CO2 g-1 FW h-1 measured by CO2 gas exchange. The results indicated that ≤10% of RL results from TCA cycle reactions, which are widely considered to dominate RL. Further analysis of the results indicated that oxidation of glucose-6-phosphate to pentose phosphate via 6-phosphogluconate (the G6P/OPP shunt) can account for >93% of CO2 released by RL.
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Affiliation(s)
- Yuan Xu
- Department of Plant Biology, Michigan State University, Michigan 48824, USA
| | - Xinyu Fu
- Department of Plant Biology, Michigan State University, Michigan 48824, USA
- Department of Energy-Plant Research Laboratory, Michigan State University, Michigan 48824, USA
| | - Thomas D Sharkey
- Department of Energy-Plant Research Laboratory, Michigan State University, Michigan 48824, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, Michigan 48824, USA
| | - Yair Shachar-Hill
- Department of Plant Biology, Michigan State University, Michigan 48824, USA
| | - and Berkley J Walker
- Department of Plant Biology, Michigan State University, Michigan 48824, USA
- Department of Energy-Plant Research Laboratory, Michigan State University, Michigan 48824, USA
- Author for communication:
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105
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Bednarski TK, Rahim M, Young JD. In vivo 2H/ 13C flux analysis in metabolism research. Curr Opin Biotechnol 2021; 71:1-8. [PMID: 34048994 DOI: 10.1016/j.copbio.2021.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/29/2021] [Accepted: 04/26/2021] [Indexed: 12/12/2022]
Abstract
Identifying the factors and mechanisms that regulate metabolism under normal and diseased states requires methods to quantify metabolic fluxes of live tissues within their physiological milieu. A number of recent developments have expanded the reach and depth of isotope-based in vivo flux analysis, which have in turn challenged existing dogmas in metabolism research. First, minimally invasive techniques of intravenous isotope infusion and sampling have advanced in vivo metabolic tracer studies in animal models and human subjects. Second, recent breakthroughs in analytical instrumentation have expanded the scope of isotope labeling measurements and reduced sample volume requirements. Third, innovative modeling approaches and publicly available software tools have facilitated rigorous analysis of sophisticated experimental designs involving multiple tracers and expansive metabolomics datasets. These developments have enabled comprehensive in vivo quantification of metabolic fluxes in specific tissues and have set the stage for integrated multi-tissue flux assays.
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Affiliation(s)
- Tomasz K Bednarski
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA
| | - Mohsin Rahim
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA
| | - Jamey D Young
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.
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106
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Zhang R, Chen B, Lin L, Zhang H, Luan T. 13C isotope-based metabolic flux analysis revealing cellular landscape of glucose metabolism in human liver cells exposed to perfluorooctanoic acid. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 770:145329. [PMID: 33515891 DOI: 10.1016/j.scitotenv.2021.145329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/15/2021] [Accepted: 01/17/2021] [Indexed: 06/12/2023]
Abstract
Perfluorooctanoic acid (PFOA) is well known to break glucose homeostasis. However, the effects of PFOA on glucose metabolism are difficult to be evaluated because related metabolites may be synthesized from other nutritional substrates. Here, the relative contribution of glucose to metabolites (e.g., pyruvate and citrate) in the PFOA-treated human liver cells (HepG2) was determined using the 13C isotope-based metabolic flux analysis (MFA), i.e., pathway activities. The relative percentage of [U-13C6] glucose-derived pyruvate in cells exposed to PFOA was not significantly different from that in the controls, indicating that the metabolic pattern of glycolysis was not substantially changed by PFOA. The pathway activity of [U-13C6] glucose-driven tricarboxylic acid (TCA) cycle was dramatically inhibited by PFOA. Consequently, mitochondrial respiratory function was phenotypically impaired by PFOA, as observed from the decreasing basal oxygen consumption rate (OCR), ATP-linked OCR and spare respiratory capacity. This study suggests that PFOA may cause the abnormal glucose metabolism via altering the metabolic pattern of TCA cycle instead of glycolysis. The MFA is strongly recommended as a promising and robust tool to address the toxicity mechanisms of contaminants associated with glucose metabolism.
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Affiliation(s)
- Ruijia Zhang
- Sate Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Baowei Chen
- Southern Marine Science and Engineering Guangdong Laboratory, School of Marine Sciences, Sun Yat-Sen University, Zhuhai 519082, China.
| | - Li Lin
- Sate Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Hui Zhang
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou 510006, China
| | - Tiangang Luan
- Sate Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China; Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, China.
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107
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Ravi A, Palamiuc L, Loughran RM, Triscott J, Arora GK, Kumar A, Tieu V, Pauli C, Reist M, Lew RJ, Houlihan SL, Fellmann C, Metallo C, Rubin MA, Emerling BM. PI5P4Ks drive metabolic homeostasis through peroxisome-mitochondria interplay. Dev Cell 2021; 56:1661-1676.e10. [PMID: 33984270 DOI: 10.1016/j.devcel.2021.04.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/29/2021] [Accepted: 04/21/2021] [Indexed: 12/16/2022]
Abstract
PI5P4Ks are a class of phosphoinositide kinases that phosphorylate PI-5-P to PI-4,5-P2. Distinct localization of phosphoinositides is fundamental for a multitude of cellular functions. Here, we identify a role for peroxisomal PI-4,5-P2 generated by the PI5P4Ks in maintaining energy balance. We demonstrate that PI-4,5-P2 regulates peroxisomal fatty acid oxidation by mediating trafficking of lipid droplets to peroxisomes, which is essential for sustaining mitochondrial metabolism. Using fluorescent-tagged lipids and metabolite tracing, we show that loss of the PI5P4Ks significantly impairs lipid uptake and β-oxidation in the mitochondria. Further, loss of PI5P4Ks results in dramatic alterations in mitochondrial structural and functional integrity, which under nutrient deprivation is further exacerbated, causing cell death. Notably, inhibition of the PI5P4Ks in cancer cells and mouse tumor models leads to decreased cell viability and tumor growth, respectively. Together, these studies reveal an unexplored role for PI5P4Ks in preserving metabolic homeostasis, which is necessary for tumorigenesis.
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Affiliation(s)
- Archna Ravi
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Lavinia Palamiuc
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Ryan M Loughran
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Joanna Triscott
- Department of Biomedical Research and Bern Center for Precision Medicine, University of Bern and Inselspital Bern, Bern 3008, Switzerland
| | - Gurpreet K Arora
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Avi Kumar
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Vivian Tieu
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Chantal Pauli
- Institute of Pathology and Molecular Pathology, University Hospital Zürich and the University of Zurich (UZH), Zurich 8006, Switzerland
| | - Matthias Reist
- Department of Biomedical Research and Bern Center for Precision Medicine, University of Bern and Inselspital Bern, Bern 3008, Switzerland
| | - Rachel J Lew
- Gladstone Institutes, San Francisco, CA 94158, USA
| | - Shauna L Houlihan
- Cancer Biology and Genetics Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Christof Fellmann
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, School of Medicine, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Christian Metallo
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
| | - Mark A Rubin
- Department of Biomedical Research and Bern Center for Precision Medicine, University of Bern and Inselspital Bern, Bern 3008, Switzerland
| | - Brooke M Emerling
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA.
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108
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Hasenour CM, Rahim M, Young JD. In Vivo Estimates of Liver Metabolic Flux Assessed by 13C-Propionate and 13C-Lactate Are Impacted by Tracer Recycling and Equilibrium Assumptions. Cell Rep 2021; 32:107986. [PMID: 32755580 PMCID: PMC7451222 DOI: 10.1016/j.celrep.2020.107986] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 06/01/2020] [Accepted: 07/13/2020] [Indexed: 01/08/2023] Open
Abstract
Isotope-based assessment of metabolic flux is achieved through a judicious balance of measurements and assumptions. Recent publications debate the validity of key assumptions used to model stable isotope labeling of liver metabolism in vivo. Here, we examine the controversy surrounding estimates of liver citric acid cycle and gluconeogenesis fluxes using a flexible modeling platform that enables rigorous testing of standard assumptions. Fasted C57BL/6J mice are infused with [13C3]lactate or [13C3]propionate isotopes, and hepatic fluxes are regressed using models with gradually increasing complexity and relaxed assumptions. We confirm that liver pyruvate cycling fluxes are incongruent between different 13C tracers in models with conventional assumptions. When models are expanded to include more labeling measurements and fewer constraining assumptions, however, liver pyruvate cycling is significant, and inconsistencies in hepatic flux estimates using [13C3]lactate and [13C3]propionate isotopes emanate, in part, from peripheral tracer recycling and incomplete isotope equilibration within the citric acid cycle.
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Affiliation(s)
- Clinton M Hasenour
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Mohsin Rahim
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA
| | - Jamey D Young
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37235, USA.
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109
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Borah K, Mendum TA, Hawkins ND, Ward JL, Beale MH, Larrouy‐Maumus G, Bhatt A, Moulin M, Haertlein M, Strohmeier G, Pichler H, Forsyth VT, Noack S, Goulding CW, McFadden J, Beste DJV. Metabolic fluxes for nutritional flexibility of Mycobacterium tuberculosis. Mol Syst Biol 2021; 17:e10280. [PMID: 33943004 PMCID: PMC8094261 DOI: 10.15252/msb.202110280] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/30/2021] [Accepted: 03/31/2021] [Indexed: 12/25/2022] Open
Abstract
The co-catabolism of multiple host-derived carbon substrates is required by Mycobacterium tuberculosis (Mtb) to successfully sustain a tuberculosis infection. However, the metabolic plasticity of this pathogen and the complexity of the metabolic networks present a major obstacle in identifying those nodes most amenable to therapeutic interventions. It is therefore critical that we define the metabolic phenotypes of Mtb in different conditions. We applied metabolic flux analysis using stable isotopes and lipid fingerprinting to investigate the metabolic network of Mtb growing slowly in our steady-state chemostat system. We demonstrate that Mtb efficiently co-metabolises either cholesterol or glycerol, in combination with two-carbon generating substrates without any compartmentalisation of metabolism. We discovered that partitioning of flux between the TCA cycle and the glyoxylate shunt combined with a reversible methyl citrate cycle is the critical metabolic nodes which underlie the nutritional flexibility of Mtb. These findings provide novel insights into the metabolic architecture that affords adaptability of bacteria to divergent carbon substrates and expand our fundamental knowledge about the methyl citrate cycle and the glyoxylate shunt.
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Affiliation(s)
- Khushboo Borah
- Department of Microbial and Cellular SciencesFaculty of Health and Medical SciencesUniversity of SurreyGuildfordUK
| | - Tom A Mendum
- Department of Microbial and Cellular SciencesFaculty of Health and Medical SciencesUniversity of SurreyGuildfordUK
| | - Nathaniel D Hawkins
- Department of Computational and Analytical SciencesRothamsted ResearchHarpendenUK
| | - Jane L Ward
- Department of Computational and Analytical SciencesRothamsted ResearchHarpendenUK
| | - Michael H Beale
- Department of Computational and Analytical SciencesRothamsted ResearchHarpendenUK
| | - Gerald Larrouy‐Maumus
- MRC Centre for Molecular Bacteriology and InfectionDepartment of Life SciencesFaculty of Natural SciencesImperial College LondonLondonUK
| | - Apoorva Bhatt
- School of BiosciencesUniversity of BirminghamEdgbastonUK
| | - Martine Moulin
- Life Sciences GroupInstitut Laue‐LangevinGrenoble Cedex 9France
- Partnership for Structural BiologyGrenoble Cedex 9France
| | - Michael Haertlein
- Life Sciences GroupInstitut Laue‐LangevinGrenoble Cedex 9France
- Partnership for Structural BiologyGrenoble Cedex 9France
| | - Gernot Strohmeier
- Austrian Centre of Industrial BiotechnologyGrazAustria
- Institute of Organic ChemistryNAWI GrazGraz University of TechnologyGrazAustria
| | - Harald Pichler
- Austrian Centre of Industrial BiotechnologyGrazAustria
- Institute of Organic ChemistryNAWI GrazGraz University of TechnologyGrazAustria
- Institute of Molecular BiotechnologyNAWI GrazBioTechMed GrazGraz University of TechnologyGrazAustria
| | - V Trevor Forsyth
- Life Sciences GroupInstitut Laue‐LangevinGrenoble Cedex 9France
- Partnership for Structural BiologyGrenoble Cedex 9France
- Faculty of Natural SciencesKeele UniversityStaffordshireUK
| | - Stephan Noack
- Institute of Bio‐ and Geosciences 1: Biotechnology 2Forschungszentrum Jülich GmbHJülichGermany
| | - Celia W Goulding
- Department of Pharmaceutical Sciences & Molecular Biology & BiochemistryUniversity of California IrvineIrvineCAUSA
| | - Johnjoe McFadden
- Department of Microbial and Cellular SciencesFaculty of Health and Medical SciencesUniversity of SurreyGuildfordUK
| | - Dany J V Beste
- Department of Microbial and Cellular SciencesFaculty of Health and Medical SciencesUniversity of SurreyGuildfordUK
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110
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In Vivo Estimation of Ketogenesis Using Metabolic Flux Analysis-Technical Aspects and Model Interpretation. Metabolites 2021; 11:metabo11050279. [PMID: 33924948 PMCID: PMC8146959 DOI: 10.3390/metabo11050279] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/21/2021] [Accepted: 04/23/2021] [Indexed: 01/26/2023] Open
Abstract
Ketogenesis occurs in liver mitochondria where acetyl-CoA molecules, derived from lipid oxidation, are condensed into acetoacetate (AcAc) and reduced to β-hydroxybutyrate (BHB). During carbohydrate scarcity, these two ketones are released into circulation at high rates and used as oxidative fuels in peripheral tissues. Despite their physiological relevance and emerging roles in a variety of diseases, endogenous ketone production is rarely measured in vivo using tracer approaches. Accurate determination of this flux requires a two-pool model, simultaneous BHB and AcAc tracers, and special consideration for the stability of the AcAc tracer and analyte. We describe the implementation of a two-pool model using a metabolic flux analysis (MFA) approach that simultaneously regresses liquid chromatography-tandem mass spectrometry (LC-MS/MS) ketone isotopologues and tracer infusion rates. Additionally, 1H NMR real-time reaction monitoring was used to evaluate AcAc tracer and analyte stability during infusion and sample analysis, which were critical for accurate flux calculations. The approach quantifies AcAc and BHB pool sizes and their rates of appearance, disposal, and exchange. Regression analysis provides confidence intervals and detects potential errors in experimental data. Complications for the physiological interpretation of individual ketone fluxes are discussed.
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111
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Moiz B, Garcia J, Basehore S, Sun A, Li A, Padmanabhan S, Albus K, Jang C, Sriram G, Clyne AM. 13C Metabolic Flux Analysis Indicates Endothelial Cells Attenuate Metabolic Perturbations by Modulating TCA Activity. Metabolites 2021; 11:metabo11040226. [PMID: 33917224 PMCID: PMC8068087 DOI: 10.3390/metabo11040226] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/30/2021] [Accepted: 04/01/2021] [Indexed: 11/16/2022] Open
Abstract
Disrupted endothelial metabolism is linked to endothelial dysfunction and cardiovascular disease. Targeted metabolic inhibitors are potential therapeutics; however, their systemic impact on endothelial metabolism remains unknown. In this study, we combined stable isotope labeling with 13C metabolic flux analysis (13C MFA) to determine how targeted inhibition of the polyol (fidarestat), pentose phosphate (DHEA), and hexosamine biosynthetic (azaserine) pathways alters endothelial metabolism. Glucose, glutamine, and a four-carbon input to the malate shuttle were important carbon sources in the baseline human umbilical vein endothelial cell (HUVEC) 13C MFA model. We observed two to three times higher glutamine uptake in fidarestat and azaserine-treated cells. Fidarestat and DHEA-treated HUVEC showed decreased 13C enrichment of glycolytic and TCA metabolites and amino acids. Azaserine-treated HUVEC primarily showed 13C enrichment differences in UDP-GlcNAc. 13C MFA estimated decreased pentose phosphate pathway flux and increased TCA activity with reversed malate shuttle direction in fidarestat and DHEA-treated HUVEC. In contrast, 13C MFA estimated increases in both pentose phosphate pathway and TCA activity in azaserine-treated cells. These data show the potential importance of endothelial malate shuttle activity and suggest that inhibiting glycolytic side branch pathways can change the metabolic network, highlighting the need to study systemic metabolic therapeutic effects.
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Affiliation(s)
- Bilal Moiz
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; (B.M.); (A.S.); (A.L.); (S.P.); (K.A.)
| | - Jonathan Garcia
- School of Bioengineering, Science, and Heath Systems, Drexel University, Philadelphia, PA 19104, USA; (J.G.); (S.B.)
| | - Sarah Basehore
- School of Bioengineering, Science, and Heath Systems, Drexel University, Philadelphia, PA 19104, USA; (J.G.); (S.B.)
| | - Angela Sun
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; (B.M.); (A.S.); (A.L.); (S.P.); (K.A.)
| | - Andrew Li
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; (B.M.); (A.S.); (A.L.); (S.P.); (K.A.)
| | - Surya Padmanabhan
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; (B.M.); (A.S.); (A.L.); (S.P.); (K.A.)
| | - Kaitlyn Albus
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; (B.M.); (A.S.); (A.L.); (S.P.); (K.A.)
| | - Cholsoon Jang
- Department of Biological Chemistry, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA 92697, USA;
| | - Ganesh Sriram
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA;
| | - Alisa Morss Clyne
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA; (B.M.); (A.S.); (A.L.); (S.P.); (K.A.)
- Correspondence: ; Tel.: +1-301-405-9806
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112
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Han JH, Jung ST, Oh MK. Improved Yield of Recombinant Protein via Flagella Regulator Deletion in Escherichia coli. Front Microbiol 2021; 12:655072. [PMID: 33790884 PMCID: PMC8005581 DOI: 10.3389/fmicb.2021.655072] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 02/22/2021] [Indexed: 11/13/2022] Open
Abstract
Protein production requires a significant amount of intracellular energy. Eliminating the flagella has been proposed to help Escherichia coli improve protein production by reducing energy consumption. In this study, the gene encoding a subunit of FlhC, a master regulator of flagella assembly, was deleted to reduce the expression of flagella-related genes. FlhC knockout in the ptsG-deleted strain triggered significant growth retardation with increased ATP levels and a higher NADPH/NADP+ ratio. Metabolic flux analysis using a 13C-labeled carbon substrate showed increased fluxes toward the pentose phosphate and tricarboxylic acid cycle pathways in the flhC- and ptsG-deleted strains. Introduction of a high copy number plasmid or overexpression of the recombinant protein in this strain restored growth rate without increasing glucose consumption. These results suggest that the metabolic burden caused by flhC deletion was resolved by recombinant protein production. The recombinant enhanced green fluorescent protein yield per glucose consumption increased 1.81-fold in the flhC mutant strain. Thus, our study demonstrates that high-yield production of the recombinant protein was achieved with reduced flagella formation.
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Affiliation(s)
- Jae-Ho Han
- Department of Chemical and Biological Engineering, Korea University, Seoul, South Korea
| | - Sang Taek Jung
- BK21 Graduate Program, Department of Biomedical Sciences, College of Medicine, Korea University, Seoul, South Korea
| | - Min-Kyu Oh
- Department of Chemical and Biological Engineering, Korea University, Seoul, South Korea
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113
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Itaconate Alters Succinate and Coenzyme A Metabolism via Inhibition of Mitochondrial Complex II and Methylmalonyl-CoA Mutase. Metabolites 2021; 11:metabo11020117. [PMID: 33670656 PMCID: PMC7922098 DOI: 10.3390/metabo11020117] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/13/2021] [Accepted: 02/14/2021] [Indexed: 12/29/2022] Open
Abstract
Itaconate is a small molecule metabolite that is endogenously produced by cis-aconitate decarboxylase-1 (ACOD1) in mammalian cells and influences numerous cellular processes. The metabolic consequences of itaconate in cells are diverse and contribute to its regulatory function. Here, we have applied isotope tracing and mass spectrometry approaches to explore how itaconate impacts various metabolic pathways in cultured cells. Itaconate is a competitive and reversible inhibitor of Complex II/succinate dehydrogenase (SDH) that alters tricarboxylic acid (TCA) cycle metabolism leading to succinate accumulation. Upon activation with coenzyme A (CoA), itaconyl-CoA inhibits adenosylcobalamin-mediated methylmalonyl-CoA (MUT) activity and, thus, indirectly impacts branched-chain amino acid (BCAA) metabolism and fatty acid diversity. Itaconate, therefore, alters the balance of CoA species in mitochondria through its impacts on TCA, amino acid, vitamin B12, and CoA metabolism. Our results highlight the diverse metabolic pathways regulated by itaconate and provide a roadmap to link these metabolites to potential downstream biological functions.
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114
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Experimentally Validated Reconstruction and Analysis of a Genome-Scale Metabolic Model of an Anaerobic Neocallimastigomycota Fungus. mSystems 2021; 6:6/1/e00002-21. [PMID: 33594000 PMCID: PMC8561657 DOI: 10.1128/msystems.00002-21] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Anaerobic gut fungi in the phylum Neocallimastigomycota typically inhabit the digestive tracts of large mammalian herbivores, where they play an integral role in the decomposition of raw lignocellulose into its constitutive sugar monomers. However, quantitative tools to study their physiology are lacking, partially due to their complex and unresolved metabolism that includes the largely uncharacterized fungal hydrogenosome. Modern omics approaches combined with metabolic modeling can be used to establish an understanding of gut fungal metabolism and develop targeted engineering strategies to harness their degradation capabilities for lignocellulosic bioprocessing. Here, we introduce a high-quality genome of the anaerobic fungus Neocallimastix lanati from which we constructed the first genome-scale metabolic model of an anaerobic fungus. Relative to its size (200 Mbp, sequenced at 62× depth), it is the least fragmented publicly available gut fungal genome to date. Of the 1,788 lignocellulolytic enzymes annotated in the genome, 585 are associated with the fungal cellulosome, underscoring the powerful lignocellulolytic potential of N. lanati. The genome-scale metabolic model captures the primary metabolism of N. lanati and accurately predicts experimentally validated substrate utilization requirements. Additionally, metabolic flux predictions are verified by 13C metabolic flux analysis, demonstrating that the model faithfully describes the underlying fungal metabolism. Furthermore, the model clarifies key aspects of the hydrogenosomal metabolism and can be used as a platform to quantitatively study these biotechnologically important yet poorly understood early-branching fungi. IMPORTANCE Recent genomic analyses have revealed that anaerobic gut fungi possess both the largest number and highest diversity of lignocellulolytic enzymes of all sequenced fungi, explaining their ability to decompose lignocellulosic substrates, e.g., agricultural waste, into fermentable sugars. Despite their potential, the development of engineering methods for these organisms has been slow due to their complex life cycle, understudied metabolism, and challenging anaerobic culture requirements. Currently, there is no framework that can be used to combine multi-omic data sets to understand their physiology. Here, we introduce a high-quality PacBio-sequenced genome of the anaerobic gut fungus Neocallimastix lanati. Beyond identifying a trove of lignocellulolytic enzymes, we use this genome to construct the first genome-scale metabolic model of an anaerobic gut fungus. The model is experimentally validated and sheds light on unresolved metabolic features common to gut fungi. Model-guided analysis will pave the way for deepening our understanding of anaerobic gut fungi and provides a systematic framework to guide strain engineering efforts of these organisms for biotechnological use.
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115
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Xu F, Ke X, Hong M, Huang M, Chen C, Tian X, Hang H, Chu J. Exploring the metabolic fate of propanol in industrial erythromycin-producing strain via 13C labeling experiments and enhancement of erythromycin production by rational metabolic engineering of Saccharopolyspora erythraea. Biochem Biophys Res Commun 2021; 542:73-79. [PMID: 33497965 DOI: 10.1016/j.bbrc.2021.01.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 01/09/2021] [Indexed: 10/22/2022]
Abstract
Propanol had been widely used as a precursor for erythromycin synthesis in industrial production. However, the knowledge on the exact metabolic fate of propanol was still unclear. In the present study, the metabolic fate of propanol in industrial erythromycin-producing strain Saccharopolyspora erythraea E3 was explored via 13C labeling experiments. An unexpected pathway in which propanol was channeled into tricarboxylic acid cycle was uncovered, resulting in uneconomic catabolism of propanol. By deleting the sucC gene, which encodes succinyl-CoA synthetase that catalyse a reaction in the unexpected propanol utilization pathway, a novel strain E3-ΔsucC was constructed. The strain E3-ΔsucC showed a significant enhancement in erythromycin production in the chemically defined medium compared to E3 (786.61 vs 392.94 mg/L). Isotopically nonstationary 13C metabolic flux analysis were employed to characterize the metabolic differences between Saccharopolyspora erythraea E3 and E3-ΔsucC. The results showed that compared with the starting strain E3, the fluxes of pentose phosphate pathway in E3-△sucC increased by almost 200%. The flux of the metabolic reaction catalyzed by succinyl-CoA synthetase in E3-ΔsucC was almost zero, while the glyoxylate bypass flux significantly increased. These new insights into the precursor utilization of antibiotic biosynthesis by rational metabolic engineering in Saccharopolyspora erythraea provided the new vision in increasing industrial production of secondary metabolites.
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Affiliation(s)
- Feng Xu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China
| | - Xiang Ke
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China
| | - Ming Hong
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China
| | - Mingzhi Huang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
| | - Chongchong Chen
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China
| | - Xiwei Tian
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China
| | - Haifeng Hang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China
| | - Ju Chu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
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116
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Chang HY, Colby SM, Du X, Gomez JD, Helf MJ, Kechris K, Kirkpatrick CR, Li S, Patti GJ, Renslow RS, Subramaniam S, Verma M, Xia J, Young JD. A Practical Guide to Metabolomics Software Development. Anal Chem 2021; 93:1912-1923. [PMID: 33467846 PMCID: PMC7859930 DOI: 10.1021/acs.analchem.0c03581] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
![]()
A growing number
of software tools have been developed for metabolomics
data processing and analysis. Many new tools are contributed by metabolomics
practitioners who have limited prior experience with software development,
and the tools are subsequently implemented by users with expertise
that ranges from basic point-and-click data analysis to advanced coding.
This Perspective is intended to introduce metabolomics software users
and developers to important considerations that determine the overall
impact of a publicly available tool within the scientific community.
The recommendations reflect the collective experience of an NIH-sponsored
Metabolomics Consortium working group that was formed with the goal
of researching guidelines and best practices for metabolomics tool
development. The recommendations are aimed at metabolomics researchers
with little formal background in programming and are organized into
three stages: (i) preparation, (ii) tool development, and (iii) distribution
and maintenance.
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Affiliation(s)
- Hui-Yin Chang
- Department of Pathology, University of Michigan, 1301 Catherine Street, Ann Arbor, Michigan 48109, United States.,Department of Biomedical Sciences and Engineering, National Central University, No. 300, Zhongda Road, Zhongli District, Taoyuan City 320, Taiwan
| | - Sean M Colby
- Biological Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, MSIN: K8-98, Richland, Washington 99352, United States
| | - Xiuxia Du
- Department of Bioinformatics & Genomics, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, North Carolina 28223, United States
| | - Javier D Gomez
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, PMB 351604, 2301 Vanderbilt Place, Nashville, Tennessee 37235, United States
| | - Maximilian J Helf
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, 533 Tower Road, Ithaca, New York 14853, United States
| | - Katerina Kechris
- Department of Biostatistics and Informatics, University of Colorado Anschutz Medical Campus, 13001 East 17th Place B119, Aurora, Colorado 80045, United States
| | - Christine R Kirkpatrick
- San Diego Supercomputer Center, University of California San Diego, MC 0505, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Shuzhao Li
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Drive, Farmington, Connecticut 06032, United States
| | - Gary J Patti
- Department of Chemistry, Department of Medicine, and Siteman Cancer Center, Washington University in St. Louis, CB 1134, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Ryan S Renslow
- Biological Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, MSIN: K8-98, Richland, Washington 99352, United States.,Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, P.O. Box 646515, Pullman, Washington 99164, United States
| | - Shankar Subramaniam
- San Diego Supercomputer Center, University of California San Diego, MC 0505, 9500 Gilman Drive, La Jolla, California 92093, United States.,Department of Bioengineering, Department of Computer Science and Engineering, Department of Cellular and Molecular Medicine, and Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive #0412, La Jolla, California 92093, United States
| | - Mukesh Verma
- Epidemiology and Genomics Research Program, National Cancer Institute, National Institutes of Health, Suite 4E102, 9609 Medical Center Drive, MSC 9763, Rockville, Maryland 20850, United States
| | - Jianguo Xia
- Faculty of Agricultural and Environmental Sciences, McGill University, 21111 Lakeshore Road, Ste. Anne de Bellevue, Quebec H9X 3 V9, Canada
| | - Jamey D Young
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, PMB 351604, 2301 Vanderbilt Place, Nashville, Tennessee 37235, United States.,Department of Molecular Physiology and Biophysics, Vanderbilt University, PMB 351604, 2301 Vanderbilt Place, Nashville, Tennessee 37235, United States
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117
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Sangha GS, Goergen CJ, Prior SJ, Ranadive SM, Clyne AM. Preclinical techniques to investigate exercise training in vascular pathophysiology. Am J Physiol Heart Circ Physiol 2021; 320:H1566-H1600. [PMID: 33385323 PMCID: PMC8260379 DOI: 10.1152/ajpheart.00719.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Atherosclerosis is a dynamic process starting with endothelial dysfunction and inflammation and eventually leading to life-threatening arterial plaques. Exercise generally improves endothelial function in a dose-dependent manner by altering hemodynamics, specifically by increased arterial pressure, pulsatility, and shear stress. However, athletes who regularly participate in high-intensity training can develop arterial plaques, suggesting alternative mechanisms through which excessive exercise promotes vascular disease. Understanding the mechanisms that drive atherosclerosis in sedentary versus exercise states may lead to novel rehabilitative methods aimed at improving exercise compliance and physical activity. Preclinical tools, including in vitro cell assays, in vivo animal models, and in silico computational methods, broaden our capabilities to study the mechanisms through which exercise impacts atherogenesis, from molecular maladaptation to vascular remodeling. Here, we describe how preclinical research tools have and can be used to study exercise effects on atherosclerosis. We then propose how advanced bioengineering techniques can be used to address gaps in our current understanding of vascular pathophysiology, including integrating in vitro, in vivo, and in silico studies across multiple tissue systems and size scales. Improving our understanding of the antiatherogenic exercise effects will enable engaging, targeted, and individualized exercise recommendations to promote cardiovascular health rather than treating cardiovascular disease that results from a sedentary lifestyle.
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Affiliation(s)
- Gurneet S Sangha
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
| | - Craig J Goergen
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana.,Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana
| | - Steven J Prior
- Department of Kinesiology, University of Maryland School of Public Health, College Park, Maryland.,Baltimore Veterans Affairs Geriatric Research, Education, and Clinical Center, Baltimore, Maryland
| | - Sushant M Ranadive
- Department of Kinesiology, University of Maryland School of Public Health, College Park, Maryland
| | - Alisa M Clyne
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
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118
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Audano M, Pedretti S, Ligorio S, Giavarini F, Caruso D, Mitro N. Investigating metabolism by mass spectrometry: From steady state to dynamic view. JOURNAL OF MASS SPECTROMETRY : JMS 2021; 56:e4658. [PMID: 33084147 DOI: 10.1002/jms.4658] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/10/2020] [Accepted: 09/14/2020] [Indexed: 06/11/2023]
Abstract
Metabolism is the set of life-sustaining reactions in organisms. These biochemical reactions are organized in metabolic pathways, in which one metabolite is converted through a series of steps catalyzed by enzymes in another chemical compound. Metabolic reactions are categorized as catabolic, the breaking down of metabolites to produce energy, and/or anabolic, the synthesis of compounds that consume energy. The balance between catabolism of the preferential fuel substrate and anabolism defines the overall metabolism of a cell or tissue. Metabolomics is a powerful tool to gain new insights contributing to the identification of complex molecular mechanisms in the field of biomedical research, both basic and translational. The enormous potential of this kind of analyses consists of two key aspects: (i) the possibility of performing so-called targeted and untargeted experiments through which it is feasible to verify or formulate a hypothesis, respectively, and (ii) the opportunity to run either steady-state analyses to have snapshots of the metabolome at a given time under different experimental conditions or dynamic analyses through the use of labeled tracers. In this review, we will highlight the most important practical (e.g., different sample extraction approaches) and conceptual steps to consider for metabolomic analysis, describing also the main application contexts in which it is used. In addition, we will provide some insights into the most innovative approaches and progress in the field of data analysis and processing, highlighting how this part is essential for the proper extrapolation and interpretation of data.
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Affiliation(s)
- Matteo Audano
- DiSFeB, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, 20133, Italy
| | - Silvia Pedretti
- DiSFeB, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, 20133, Italy
| | - Simona Ligorio
- DiSFeB, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, 20133, Italy
| | - Flavio Giavarini
- DiSFeB, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, 20133, Italy
| | - Donatella Caruso
- DiSFeB, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, 20133, Italy
| | - Nico Mitro
- DiSFeB, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, 20133, Italy
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119
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Lim EW, Parker SJ, Metallo CM. Deuterium Tracing to Interrogate Compartment-Specific NAD(P)H Metabolism in Cultured Mammalian Cells. Methods Mol Biol 2020; 2088:51-71. [PMID: 31893370 DOI: 10.1007/978-1-0716-0159-4_4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Oxidation-reduction (redox) reactions are ubiquitous in biology and typically occur in specific subcellular compartments. In cells, the electron transfer between molecules and organelles is commonly facilitated by pyridine nucleotides such as nicotinamide adenine dinucleotide phosphate (NADPH) and nicotinamide adenine dinucleotide (NADH). While often taken for granted, these metabolic reactions are critically important for maintaining redox homeostasis and biochemical potentials across membranes. While 13C tracing and metabolic flux analysis (MFA) have emerged as powerful tools to study intracellular metabolism, this approach is limited when applied to pathways catalyzed in multiple cellular compartments. To address this issue, we and others have applied 2H (deuterium) tracers to observe transfer of labeled hydride anions, which accompanies electron transfer. Furthermore, we have developed a reporter system for indirectly quantifying NADPH enrichment in specific subcellular compartments. Here, we provide a detailed description of 2H tracing applications and the interrogation of mitochondrial versus cytosolic NAD(P)H metabolism in cultured mammalian cells. Specifically, we describe the generation of reporter cell lines that express epitope-tagged R132H-IDH1 or R172K-IDH2 and produce (D)2-hydroxyglutarate in a doxycycline-dependent manner. These tools and methods allow for quantitation of reducing equivalent turnover rates, the directionality of pathways present in multiple compartments, and the estimation of pathway contributions to NADPH pools.
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Affiliation(s)
- Esther W Lim
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Seth J Parker
- Department of Radiation Oncology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, USA
| | - Christian M Metallo
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
- Moores Cancer Center, University of California San Diego, La Jolla, CA, USA.
- Diabetes and Endocrinology Research Center, University of California San Diego, La Jolla, CA, USA.
- Institute of Engineering in Medicine, University of California San Diego, La Jolla, CA, USA.
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120
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Maniam S, Maniam S. Cancer Cell Metabolites: Updates on Current Tracing Methods. Chembiochem 2020; 21:3476-3488. [PMID: 32639076 DOI: 10.1002/cbic.202000290] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 07/07/2020] [Indexed: 12/15/2022]
Abstract
Cancer is the second leading cause of death-1 in 6 deaths globally is due to cancer. Cancer metabolism is a complex and one of the most actively researched area in cancer biology. Metabolic reprogramming in cancer cells entails activities that involve several enzymes and metabolites to convert nutrient into building blocks that alter energy metabolism to fuel rapid cell division. Metabolic dependencies in cancer generate signature metabolites that have key regulatory roles in tumorigenesis. In this minireview, we highlight recent advances in the popular methods ingrained in biochemistry research such as stable and flux isotope analysis, as well as radioisotope labeling, which are valuable in elucidating cancer metabolites. These methods together with analytical tools such as chromatography, nuclear magnetic resonance spectroscopy and mass spectrometry have helped to bring about exploratory work in understanding the role of important as well as obscure metabolites in cancer cells. Information obtained from these analyses significantly contribute in the diagnosis and prognosis of tumors leading to potential therapeutic targets for cancer therapy.
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Affiliation(s)
- Subashani Maniam
- School of Applied Science, RMIT University, 240 La Trobe Street, Melbourne, VIC 3001, Australia
| | - Sandra Maniam
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia
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121
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Suthers PF, Foster CJ, Sarkar D, Wang L, Maranas CD. Recent advances in constraint and machine learning-based metabolic modeling by leveraging stoichiometric balances, thermodynamic feasibility and kinetic law formalisms. Metab Eng 2020; 63:13-33. [PMID: 33310118 DOI: 10.1016/j.ymben.2020.11.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 11/13/2020] [Accepted: 11/27/2020] [Indexed: 12/16/2022]
Abstract
Understanding the governing principles behind organisms' metabolism and growth underpins their effective deployment as bioproduction chassis. A central objective of metabolic modeling is predicting how metabolism and growth are affected by both external environmental factors and internal genotypic perturbations. The fundamental concepts of reaction stoichiometry, thermodynamics, and mass action kinetics have emerged as the foundational principles of many modeling frameworks designed to describe how and why organisms allocate resources towards both growth and bioproduction. This review focuses on the latest algorithmic advancements that have integrated these foundational principles into increasingly sophisticated quantitative frameworks.
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Affiliation(s)
- Patrick F Suthers
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA; DOE Center for Advanced Bioenergy and Bioproducts Innovation, The Pennsylvania State University, University Park, PA, USA
| | - Charles J Foster
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Debolina Sarkar
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Lin Wang
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Costas D Maranas
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA; DOE Center for Advanced Bioenergy and Bioproducts Innovation, The Pennsylvania State University, University Park, PA, USA.
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122
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McCully AL, Onyeziri MC, LaSarre B, Gliessman JR, McKinlay JB. Reductive tricarboxylic acid cycle enzymes and reductive amino acid synthesis pathways contribute to electron balance in a Rhodospirillum rubrum Calvin-cycle mutant. MICROBIOLOGY-SGM 2020; 166:199-211. [PMID: 31774392 DOI: 10.1099/mic.0.000877] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Purple non-sulfur bacteria (PNSB) use light for energy and organic substrates for carbon and electrons when growing photoheterotrophically. This lifestyle generates more reduced electron carriers than are required for biosynthesis, even during consumption of some of the most oxidized organic substrates like malate and fumarate. Reduced electron carriers not used in biosynthesis must still be oxidized for photoheterotrophic growth to occur. Diverse PNSB commonly rely on the CO2-fixing Calvin cycle to oxidize reduced electron carriers. Some PNSB also produce H2 or reduce terminal electron acceptors as alternatives to the Calvin cycle. Rhodospirillum rubrum Calvin-cycle mutants defy this trend by growing phototrophically on malate or fumarate without H2 production or access to terminal electron acceptors. We used 13C-tracer experiments to examine how a Rs. rubrum Calvin-cycle mutant maintains electron balance under such conditions. We detected the reversal of some tricarboxylic acid cycle enzymes, carrying reductive flux from malate or fumarate to αKG. This pathway and the reductive synthesis of αKG-derived amino acids are likely important for electron balance, as supplementing the growth medium with αKG-derived amino acids prevented Rs. rubrum Calvin-cycle-mutant growth unless a terminal electron acceptor was provided. Flux estimates also suggested that the Calvin-cycle mutant preferentially synthesized isoleucine using the reductive threonine-dependent pathway instead of the less-reductive citramalate-dependent pathway. Collectively, our results suggest that alternative biosynthetic pathways can contribute to electron balance within the constraints of a relatively constant biomass composition.
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Affiliation(s)
- Alexandra L McCully
- Present address: Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA.,Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | | | - Breah LaSarre
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | | | - James B McKinlay
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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123
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Metabolic flux analysis reaching genome wide coverage: lessons learned and future perspectives. Curr Opin Chem Eng 2020. [DOI: 10.1016/j.coche.2020.05.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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124
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Bedaquiline reprograms central metabolism to reveal glycolytic vulnerability in Mycobacterium tuberculosis. Nat Commun 2020; 11:6092. [PMID: 33257709 PMCID: PMC7705017 DOI: 10.1038/s41467-020-19959-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 11/04/2020] [Indexed: 02/06/2023] Open
Abstract
The approval of bedaquiline (BDQ) for the treatment of tuberculosis has generated substantial interest in inhibiting energy metabolism as a therapeutic paradigm. However, it is not known precisely how BDQ triggers cell death in Mycobacterium tuberculosis (Mtb). Using 13C isotopomer analysis, we show that BDQ-treated Mtb redirects central carbon metabolism to induce a metabolically vulnerable state susceptible to genetic disruption of glycolysis and gluconeogenesis. Metabolic flux profiles indicate that BDQ-treated Mtb is dependent on glycolysis for ATP production, operates a bifurcated TCA cycle by increasing flux through the glyoxylate shunt, and requires enzymes of the anaplerotic node and methylcitrate cycle. Targeting oxidative phosphorylation (OXPHOS) with BDQ and simultaneously inhibiting substrate level phosphorylation via genetic disruption of glycolysis leads to rapid sterilization. Our findings provide insight into the metabolic mechanism of BDQ-induced cell death and establish a paradigm for the development of combination therapies that target OXPHOS and glycolysis.
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125
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Wang Y, Wondisford FE, Song C, Zhang T, Su X. Metabolic Flux Analysis-Linking Isotope Labeling and Metabolic Fluxes. Metabolites 2020; 10:metabo10110447. [PMID: 33172051 PMCID: PMC7694648 DOI: 10.3390/metabo10110447] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/03/2020] [Accepted: 11/04/2020] [Indexed: 01/02/2023] Open
Abstract
Metabolic flux analysis (MFA) is an increasingly important tool to study metabolism quantitatively. Unlike the concentrations of metabolites, the fluxes, which are the rates at which intracellular metabolites interconvert, are not directly measurable. MFA uses stable isotope labeled tracers to reveal information related to the fluxes. The conceptual idea of MFA is that in tracer experiments the isotope labeling patterns of intracellular metabolites are determined by the fluxes, therefore by measuring the labeling patterns we can infer the fluxes in the network. In this review, we will discuss the basic concept of MFA using a simplified upper glycolysis network as an example. We will show how the fluxes are reflected in the isotope labeling patterns. The central idea we wish to deliver is that under metabolic and isotopic steady-state the labeling pattern of a metabolite is the flux-weighted average of the substrates’ labeling patterns. As a result, MFA can tell the relative contributions of converging metabolic pathways only when these pathways make substrates in different labeling patterns for the shared product. This is the fundamental principle guiding the design of isotope labeling experiment for MFA including tracer selection. In addition, we will also discuss the basic biochemical assumptions of MFA, and we will show the flux-solving procedure and result evaluation. Finally, we will highlight the link between isotopically stationary and nonstationary flux analysis.
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Affiliation(s)
- Yujue Wang
- Department of Medicine, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA; (Y.W.); (F.E.W.)
- Metabolomics Shared Resource, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA
| | - Fredric E. Wondisford
- Department of Medicine, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA; (Y.W.); (F.E.W.)
| | - Chi Song
- Division of Biostatistics, College of Public Health, The Ohio State University, Columbus, OH 43210, USA;
| | - Teng Zhang
- Department of Mathematics, University of Central Florida, Orlando, FL 32816, USA;
| | - Xiaoyang Su
- Department of Medicine, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA; (Y.W.); (F.E.W.)
- Metabolomics Shared Resource, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA
- Correspondence: ; Tel.: +1-732-235-5447
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126
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Pannala VR, Estes SK, Rahim M, Trenary I, O’Brien TP, Shiota C, Printz RL, Reifman J, Shiota M, Young JD, Wallqvist A. Toxicant-Induced Metabolic Alterations in Lipid and Amino Acid Pathways Are Predictive of Acute Liver Toxicity in Rats. Int J Mol Sci 2020; 21:ijms21218250. [PMID: 33158035 PMCID: PMC7663358 DOI: 10.3390/ijms21218250] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 02/07/2023] Open
Abstract
Liver disease and disorders associated with aberrant hepatocyte metabolism can be initiated via drug and environmental toxicant exposures. In this study, we tested the hypothesis that gene and metabolic profiling can reveal commonalities in liver response to different toxicants and provide the capability to identify early signatures of acute liver toxicity. We used Sprague Dawley rats and three classical hepatotoxicants: acetaminophen (2 g/kg), bromobenzene (0.4 g/kg), and carbon tetrachloride (0.3 g/kg), to identify early perturbations in liver metabolism after a single acute exposure dose. We measured changes in liver genes and plasma metabolites at two time points (5 and 10 h) and used genome-scale metabolic models to identify commonalities in liver responses across the three toxicants. We found strong correlations for gene and metabolic profiles between the toxicants, indicative of similarities in the liver response to toxicity. We identified several injury-specific pathways in lipid and amino acid metabolism that changed similarly across the three toxicants. Our findings suggest that several plasma metabolites in lipid and amino acid metabolism are strongly associated with the progression of liver toxicity, and as such, could be targeted and clinically assessed for their potential as early predictors of acute liver toxicity.
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Affiliation(s)
- Venkat R. Pannala
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Development Command, Fort Detrick, MD 21702, USA;
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD 20817, USA
- Correspondence: (V.R.P.); (J.D.Y.); (A.W.); Tel.: +1-301-619-1976 (V.R.P.); +1-615-343-4253 (J.D.Y.); +1-301-619-1989 (A.W.); Fax: +301-619-1983 (A.W. & V.R.P.); +615-343-7951 (J.D.Y.)
| | - Shanea K. Estes
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; (S.K.E.); (T.P.O.); (C.S.); (R.L.P.); (M.S.)
| | - Mohsin Rahim
- Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Engineering, Nashville, TN 37232, USA; (M.R.); (I.T.)
| | - Irina Trenary
- Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Engineering, Nashville, TN 37232, USA; (M.R.); (I.T.)
| | - Tracy P. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; (S.K.E.); (T.P.O.); (C.S.); (R.L.P.); (M.S.)
| | - Chiyo Shiota
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; (S.K.E.); (T.P.O.); (C.S.); (R.L.P.); (M.S.)
| | - Richard L. Printz
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; (S.K.E.); (T.P.O.); (C.S.); (R.L.P.); (M.S.)
| | - Jaques Reifman
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Development Command, Fort Detrick, MD 21702, USA;
| | - Masakazu Shiota
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; (S.K.E.); (T.P.O.); (C.S.); (R.L.P.); (M.S.)
| | - Jamey D. Young
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; (S.K.E.); (T.P.O.); (C.S.); (R.L.P.); (M.S.)
- Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Engineering, Nashville, TN 37232, USA; (M.R.); (I.T.)
- Correspondence: (V.R.P.); (J.D.Y.); (A.W.); Tel.: +1-301-619-1976 (V.R.P.); +1-615-343-4253 (J.D.Y.); +1-301-619-1989 (A.W.); Fax: +301-619-1983 (A.W. & V.R.P.); +615-343-7951 (J.D.Y.)
| | - Anders Wallqvist
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Development Command, Fort Detrick, MD 21702, USA;
- Correspondence: (V.R.P.); (J.D.Y.); (A.W.); Tel.: +1-301-619-1976 (V.R.P.); +1-615-343-4253 (J.D.Y.); +1-301-619-1989 (A.W.); Fax: +301-619-1983 (A.W. & V.R.P.); +615-343-7951 (J.D.Y.)
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127
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Antoniewicz MR. A guide to metabolic flux analysis in metabolic engineering: Methods, tools and applications. Metab Eng 2020; 63:2-12. [PMID: 33157225 DOI: 10.1016/j.ymben.2020.11.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 10/28/2020] [Accepted: 11/01/2020] [Indexed: 12/22/2022]
Abstract
The field of metabolic engineering is primarily concerned with improving the biological production of value-added chemicals, fuels and pharmaceuticals through the design, construction and optimization of metabolic pathways, redirection of intracellular fluxes, and refinement of cellular properties relevant for industrial bioprocess implementation. Metabolic network models and metabolic fluxes are central concepts in metabolic engineering, as was emphasized in the first paper published in this journal, "Metabolic fluxes and metabolic engineering" (Metabolic Engineering, 1: 1-11, 1999). In the past two decades, a wide range of computational, analytical and experimental approaches have been developed to interrogate the capabilities of biological systems through analysis of metabolic network models using techniques such as flux balance analysis (FBA), and quantify metabolic fluxes using constrained-based modeling approaches such as metabolic flux analysis (MFA) and more advanced experimental techniques based on the use of stable-isotope tracers, i.e. 13C-metabolic flux analysis (13C-MFA). In this review, we describe the basic principles of metabolic flux analysis, discuss current best practices in flux quantification, highlight potential pitfalls and alternative approaches in the application of these tools, and give a broad overview of pragmatic applications of flux analysis in metabolic engineering practice.
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Affiliation(s)
- Maciek R Antoniewicz
- Department of Chemical Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Michigan, Ann Arbor, MI, 48109, USA.
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128
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Odenwelder DC, Lu X, Harcum SW. Induced pluripotent stem cells can utilize lactate as a metabolic substrate to support proliferation. Biotechnol Prog 2020; 37:e3090. [PMID: 33029909 DOI: 10.1002/btpr.3090] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 09/10/2020] [Accepted: 09/28/2020] [Indexed: 01/07/2023]
Abstract
Human-induced pluripotent stem cells (iPSCs) hold the promise to improve cell-based therapies. Yet, to meet rising demands and become clinically impactful, sufficient high-quality iPSCs in quantity must be generated, a task that exceeds current capabilities. In this study, K3 iPSCs cultures were examined using parallel-labeling metabolic flux analysis (13 C-MFA) to quantify intracellular fluxes at relevant bioprocessing stages: glucose concentrations representative of initial media concentrations and high lactate concentrations representative of fed-batch culture conditions, prior to and after bolus glucose feeds. The glucose and lactate concentrations are also representative of concentrations that might be encountered at different locations within 3D cell aggregates. Furthermore, a novel method was developed to allow the isotopic tracer [U-13 C3 ] lactate to be used in the 13 C-MFA model. The results indicated that high extracellular lactate concentrations decreased glucose consumption and lactate production, while glucose concentrations alone did not affect rates of aerobic glycolysis. Moreover, for the high lactate cultures, lactate was used as a metabolic substrate to support oxidative mitochondrial metabolism. These results demonstrate that iPSCs have metabolic flexibility and possess the capacity to metabolize lactate to support exponential growth, and that high lactate concentrations alone do not adversely impact iPSC proliferation.
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Affiliation(s)
- Daniel C Odenwelder
- Department of Bioengineering, Clemson University, Clemson, South Carolina, USA
| | - Xiaoming Lu
- Department of Bioengineering, Clemson University, Clemson, South Carolina, USA
- Department of Biomolecular and Chemical Engineering, Clemson University, Clemson, South Carolina, USA
| | - Sarah W Harcum
- Department of Bioengineering, Clemson University, Clemson, South Carolina, USA
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129
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AuBuchon-Elder T, Coneva V, Goad DM, Jenkins LM, Yu Y, Allen DK, Kellogg EA. Sterile Spikelets Contribute to Yield in Sorghum and Related Grasses. THE PLANT CELL 2020; 32:3500-3518. [PMID: 32873633 PMCID: PMC7610286 DOI: 10.1105/tpc.20.00424] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/05/2020] [Accepted: 08/26/2020] [Indexed: 05/14/2023]
Abstract
Sorghum (Sorghum bicolor) and its relatives in the grass tribe Andropogoneae bear their flowers in pairs of spikelets in which one spikelet (seed-bearing or sessile spikelet [SS]) of the pair produces a seed and the other is sterile or male (staminate). This division of function does not occur in other major cereals such as wheat (Triticum aestivum) or rice (Oryza sativa). Additionally, one bract of the SS spikelet often produces a long extension, the awn, that is in the same position as, but independently derived from, that of wheat and rice. The function of the sterile spikelet is unknown and that of the awn has not been tested in Andropogoneae. We used radioactive and stable isotopes of carbon, RNA sequencing of metabolically important enzymes, and immunolocalization of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) to show that the sterile spikelet assimilates carbon, which is translocated to the largely heterotrophic SS. The awn shows no evidence of photosynthesis. These results apply to distantly related species of Andropogoneae. Removal of sterile spikelets in sorghum significantly decreases seed weight (yield) by ∼9%. Thus, the sterile spikelet, but not the awn, affects yield in the cultivated species and fitness in the wild species.
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Affiliation(s)
| | | | - David M Goad
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
- Department of Biology, Washington University, St. Louis, Missouri 63130
| | - Lauren M Jenkins
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
- U.S. Department of Agriculture-Agricultural Research Service, St. Louis, Missouri 63132
| | - Yunqing Yu
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
| | - Doug K Allen
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
- U.S. Department of Agriculture-Agricultural Research Service, St. Louis, Missouri 63132
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130
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Jaiswal D, Wangikar PP. Dynamic Inventory of Intermediate Metabolites of Cyanobacteria in a Diurnal Cycle. iScience 2020; 23:101704. [PMID: 33196027 PMCID: PMC7644974 DOI: 10.1016/j.isci.2020.101704] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/15/2020] [Accepted: 10/15/2020] [Indexed: 11/25/2022] Open
Abstract
Cyanobacteria are gaining importance both as hosts for photoautotrophic production of chemicals and as model systems for studies of diurnal lifestyle. The proteome and transcriptome of cyanobacteria have been closely examined under diurnal growth, whereas the downstream effects on the intermediary metabolism have not received sufficient attention. The present study focuses on identifying the cellular metabolites whose inventories undergo dramatic changes in a fast-growing cyanobacterium, Synechococcus elongatus PCC 11801. We identified and quantified 67 polar metabolites, whose inventory changes significantly during diurnal growth, with some metabolites changing by 100-fold. The Calvin-Benson-Bassham cycle intermediates peak at midday to support fast growth. The hitherto unexplored γ-glutamyl peptides act as reservoirs of amino acids. Interestingly, several storage molecules or their precursors accumulate during the dark phase, dispelling the notion that all biosynthetic activity takes place in the light phase. Our results will guide metabolic modeling and strain engineering of cyanobacteria. We identify and quantify 67 polar intermediate metabolites in cyanobacteria via LC-MS A number of metabolites show large variations during the diurnal cycle Intermediates of the CBB cycle peak at midday, coinciding with peak in growth rate Gamma-glutamyl dipeptides identified as new storage compounds that peak at dawn
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Affiliation(s)
- Damini Jaiswal
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Pramod P Wangikar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.,DBT-PAN IIT Centre for Bioenergy, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.,Wadhwani Research Centre for Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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131
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Autotrophic and mixotrophic metabolism of an anammox bacterium revealed by in vivo 13C and 2H metabolic network mapping. ISME JOURNAL 2020; 15:673-687. [PMID: 33082573 PMCID: PMC8027424 DOI: 10.1038/s41396-020-00805-w] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 09/23/2020] [Accepted: 10/02/2020] [Indexed: 12/20/2022]
Abstract
Anaerobic ammonium-oxidizing (anammox) bacteria mediate a key step in the biogeochemical nitrogen cycle and have been applied worldwide for the energy-efficient removal of nitrogen from wastewater. However, outside their core energy metabolism, little is known about the metabolic networks driving anammox bacterial anabolism and use of different carbon and energy substrates beyond genome-based predictions. Here, we experimentally resolved the central carbon metabolism of the anammox bacterium Candidatus ‘Kuenenia stuttgartiensis’ using time-series 13C and 2H isotope tracing, metabolomics, and isotopically nonstationary metabolic flux analysis. Our findings confirm predicted metabolic pathways used for CO2 fixation, central metabolism, and amino acid biosynthesis in K. stuttgartiensis, and reveal several instances where genomic predictions are not supported by in vivo metabolic fluxes. This includes the use of the oxidative branch of an incomplete tricarboxylic acid cycle for alpha-ketoglutarate biosynthesis, despite the genome not having an annotated citrate synthase. We also demonstrate that K. stuttgartiensis is able to directly assimilate extracellular formate via the Wood–Ljungdahl pathway instead of oxidizing it completely to CO2 followed by reassimilation. In contrast, our data suggest that K. stuttgartiensis is not capable of using acetate as a carbon or energy source in situ and that acetate oxidation occurred via the metabolic activity of a low-abundance microorganism in the bioreactor’s side population. Together, these findings provide a foundation for understanding the carbon metabolism of anammox bacteria at a systems-level and will inform future studies aimed at elucidating factors governing their function and niche differentiation in natural and engineered ecosystems.
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132
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Wang Z, Ning T, Song A, Rutter J, Wang QA, Jiang L. Chronic cold exposure enhances glucose oxidation in brown adipose tissue. EMBO Rep 2020; 21:e50085. [PMID: 33043581 PMCID: PMC7645266 DOI: 10.15252/embr.202050085] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 09/02/2020] [Accepted: 09/10/2020] [Indexed: 01/20/2023] Open
Abstract
The cultured brown adipocytes can oxidize glucose in vitro, but it is still not fully clear whether brown adipose tissue (BAT) could completely oxidize glucose in vivo. Although positron emission tomography (PET) with 18F‐fluorodeoxyglucose (18F‐FDG) showed a high level of glucose uptake in the activated BAT, the non‐metabolizable 18F‐FDG cannot fully demonstrate intracellular glucose metabolism. Through in vivo [U‐13C]glucose tracing, here we show that chronic cold exposure dramatically activates glucose oxidation in BAT and the browning/beiging subcutaneous white adipose tissue (sWAT). Specifically, chronic cold exposure enhances glucose flux into the mitochondrial TCA cycle. Metabolic flux analysis models that β3‐adrenergic receptor (β3‐AR) agonist significantly enhances the flux of mitochondrial pyruvate uptake through mitochondrial pyruvate carrier (MPC) in the differentiated primary brown adipocytes. Furthermore, in vivo MPC inhibition blocks cold‐induced glucose oxidation and impairs body temperature maintenance in mice. Together, mitochondrial pyruvate uptake and oxidation serve an important energy source in the chronic cold exposure activated BAT and beige adipose tissue, which supports a role for glucose oxidation in brown fat thermogenesis.
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Affiliation(s)
- Zhichao Wang
- Department of Molecular & Cellular Endocrinology, Diabetes and Metabolism Research Institute, City of Hope Medical Center, Duarte, CA, USA
| | - Tinglu Ning
- Department of Molecular & Cellular Endocrinology, Diabetes and Metabolism Research Institute, City of Hope Medical Center, Duarte, CA, USA
| | - Anying Song
- Department of Molecular & Cellular Endocrinology, Diabetes and Metabolism Research Institute, City of Hope Medical Center, Duarte, CA, USA
| | - Jared Rutter
- Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT, USA.,Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Qiong A Wang
- Department of Molecular & Cellular Endocrinology, Diabetes and Metabolism Research Institute, City of Hope Medical Center, Duarte, CA, USA.,Comprehensive Cancer Center, Beckman Research Institute, City of Hope Medical Center, Duarte, CA, USA
| | - Lei Jiang
- Department of Molecular & Cellular Endocrinology, Diabetes and Metabolism Research Institute, City of Hope Medical Center, Duarte, CA, USA.,Comprehensive Cancer Center, Beckman Research Institute, City of Hope Medical Center, Duarte, CA, USA
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133
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Gaglio D, Bonanomi M, Valtorta S, Bharat R, Ripamonti M, Conte F, Fiscon G, Righi N, Napodano E, Papa F, Raccagni I, Parker SJ, Cifola I, Camboni T, Paci P, Colangelo AM, Vanoni M, Metallo CM, Moresco RM, Alberghina L. Disruption of redox homeostasis for combinatorial drug efficacy in K-Ras tumors as revealed by metabolic connectivity profiling. Cancer Metab 2020; 8:22. [PMID: 33005401 PMCID: PMC7523077 DOI: 10.1186/s40170-020-00227-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/06/2020] [Indexed: 12/14/2022] Open
Abstract
Abstract Background Rewiring of metabolism induced by oncogenic K-Ras in cancer cells involves both glucose and glutamine utilization sustaining enhanced, unrestricted growth. The development of effective anti-cancer treatments targeting metabolism may be facilitated by the identification and rational combinatorial targeting of metabolic pathways. Methods We performed mass spectrometric metabolomics analysis in vitro and in vivo experiments to evaluate the efficacy of drugs and identify metabolic connectivity. Results We show that K-Ras-mutant lung and colon cancer cells exhibit a distinct metabolic rewiring, the latter being more dependent on respiration. Combined treatment with the glutaminase inhibitor CB-839 and the PI3K/aldolase inhibitor NVP-BKM120 more consistently reduces cell growth of tumor xenografts. Maximal growth inhibition correlates with the disruption of redox homeostasis, involving loss of reduced glutathione regeneration, redox cofactors, and a decreased connectivity among metabolites primarily involved in nucleic acid metabolism. Conclusions Our findings open the way to develop metabolic connectivity profiling as a tool for a selective strategy of combined drug repositioning in precision oncology.
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Affiliation(s)
- Daniela Gaglio
- Institute of Molecular Bioimaging and Physiology (IBFM), National Research Council (CNR), Segrate, MI Italy.,ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy
| | - Marcella Bonanomi
- ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Silvia Valtorta
- Institute of Molecular Bioimaging and Physiology (IBFM), National Research Council (CNR), Segrate, MI Italy.,ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Department of Medicine and Surgery and Tecnomed Foundation, University of Milano-Bicocca, Via Cadore 48, 20900 Monza, Italy
| | - Rohit Bharat
- ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Marilena Ripamonti
- Institute of Molecular Bioimaging and Physiology (IBFM), National Research Council (CNR), Segrate, MI Italy.,ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy
| | - Federica Conte
- ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Institute for Systems Analysis and Computer Science "Antonio Ruberti", National Research Council, Rome, Italy
| | - Giulia Fiscon
- ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Institute for Systems Analysis and Computer Science "Antonio Ruberti", National Research Council, Rome, Italy
| | - Nicole Righi
- ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Elisabetta Napodano
- Institute of Molecular Bioimaging and Physiology (IBFM), National Research Council (CNR), Segrate, MI Italy.,ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy
| | - Federico Papa
- ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Institute for Systems Analysis and Computer Science "Antonio Ruberti", National Research Council, Rome, Italy
| | - Isabella Raccagni
- Institute of Molecular Bioimaging and Physiology (IBFM), National Research Council (CNR), Segrate, MI Italy.,ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Nuclear Medicine Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Seth J Parker
- Department of Bioengineering, University of California, San Diego, La Jolla, CA USA.,Moores Cancer Center, University of California, San Diego, La Jolla, CA USA
| | - Ingrid Cifola
- Institute for Biomedical Technologies (ITB), National Research Council (CNR), Segrate, Milan, Italy
| | - Tania Camboni
- Institute for Biomedical Technologies (ITB), National Research Council (CNR), Segrate, Milan, Italy
| | - Paola Paci
- ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Institute for Systems Analysis and Computer Science "Antonio Ruberti", National Research Council, Rome, Italy.,Department of Computer, Control and Management Engineering, Sapienza University of Rome, Rome, Italy
| | - Anna Maria Colangelo
- ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Marco Vanoni
- ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Christian M Metallo
- Department of Bioengineering, University of California, San Diego, La Jolla, CA USA.,Moores Cancer Center, University of California, San Diego, La Jolla, CA USA
| | - Rosa Maria Moresco
- Institute of Molecular Bioimaging and Physiology (IBFM), National Research Council (CNR), Segrate, MI Italy.,ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Department of Medicine and Surgery and Tecnomed Foundation, University of Milano-Bicocca, Via Cadore 48, 20900 Monza, Italy
| | - Lilia Alberghina
- ISBE. IT/Centre of Systems Biology, Piazza della Scienza 4, 20126 Milan, Italy.,Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
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134
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Intracellular Mycobacterium tuberculosis Exploits Multiple Host Nitrogen Sources during Growth in Human Macrophages. Cell Rep 2020; 29:3580-3591.e4. [PMID: 31825837 PMCID: PMC6915324 DOI: 10.1016/j.celrep.2019.11.037] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 07/05/2019] [Accepted: 11/07/2019] [Indexed: 02/05/2023] Open
Abstract
Nitrogen metabolism of Mycobacterium tuberculosis (Mtb) is crucial for the survival of this important pathogen in its primary human host cell, the macrophage, but little is known about the source(s) and their assimilation within this intracellular niche. Here, we have developed 15N-flux spectral ratio analysis (15N-FSRA) to explore Mtb’s nitrogen metabolism; we demonstrate that intracellular Mtb has access to multiple amino acids in the macrophage, including glutamate, glutamine, aspartate, alanine, glycine, and valine; and we identify glutamine as the predominant nitrogen donor. Each nitrogen source is uniquely assimilated into specific amino acid pools, indicating compartmentalized metabolism during intracellular growth. We have discovered that serine is not available to intracellular Mtb, and we show that a serine auxotroph is attenuated in macrophages. This work provides a systems-based tool for exploring the nitrogen metabolism of intracellular pathogens and highlights the enzyme phosphoserine transaminase as an attractive target for the development of novel anti-tuberculosis therapies. Mycobacterium tuberculosis utilizes multiple amino acids as nitrogen sources in human macrophages 15N-FSRA tool identified the intracellular nitrogen sources Glutamine is the predominant nitrogen donor for M. tuberculosis Serine biosynthesis is essential for the survival of intracellular M. tuberculosis
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135
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Muyyarikkandy MS, McLeod M, Maguire M, Mahar R, Kattapuram N, Zhang C, Surugihalli C, Muralidaran V, Vavilikolanu K, Mathews CE, Merritt ME, Sunny NE. Branched chain amino acids and carbohydrate restriction exacerbate ketogenesis and hepatic mitochondrial oxidative dysfunction during NAFLD. FASEB J 2020; 34:14832-14849. [PMID: 32918763 DOI: 10.1096/fj.202001495r] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/10/2020] [Accepted: 08/24/2020] [Indexed: 12/16/2022]
Abstract
Mitochondrial adaptation during non-alcoholic fatty liver disease (NAFLD) include remodeling of ketogenic flux and sustained tricarboxylic acid (TCA) cycle activity, which are concurrent to onset of oxidative stress. Over 70% of obese humans have NAFLD and ketogenic diets are common weight loss strategies. However, the effectiveness of ketogenic diets toward alleviating NAFLD remains unclear. We hypothesized that chronic ketogenesis will worsen metabolic dysfunction and oxidative stress during NAFLD. Mice (C57BL/6) were kept (for 16-wks) on either a low-fat, high-fat, or high-fat diet supplemented with 1.5X branched chain amino acids (BCAAs) by replacing carbohydrate calories (ketogenic). The ketogenic diet induced hepatic lipid oxidation and ketogenesis, and produced multifaceted changes in flux through the individual steps of the TCA cycle. Higher rates of hepatic oxidative fluxes fueled by the ketogenic diet paralleled lower rates of de novo lipogenesis. Interestingly, this metabolic remodeling did not improve insulin resistance, but induced fibrogenic genes and inflammation in the liver. Under a chronic "ketogenic environment," the hepatocyte diverted more acetyl-CoA away from lipogenesis toward ketogenesis and TCA cycle, a milieu which can hasten oxidative stress and inflammation. In summary, chronic exposure to ketogenic environment during obesity and NAFLD has the potential to aggravate hepatic mitochondrial dysfunction.
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Affiliation(s)
| | - Marc McLeod
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Meghan Maguire
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Rohit Mahar
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Nathan Kattapuram
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Christine Zhang
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Chaitra Surugihalli
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Vaishna Muralidaran
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Kruthi Vavilikolanu
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
| | - Clayton E Mathews
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Nishanth E Sunny
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, USA
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136
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Atom Identifiers Generated by a Neighborhood-Specific Graph Coloring Method Enable Compound Harmonization across Metabolic Databases. Metabolites 2020; 10:metabo10090368. [PMID: 32933023 PMCID: PMC7570338 DOI: 10.3390/metabo10090368] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 09/04/2020] [Accepted: 09/08/2020] [Indexed: 02/06/2023] Open
Abstract
Metabolic flux analysis requires both a reliable metabolic model and reliable metabolic profiles in characterizing metabolic reprogramming. Advances in analytic methodologies enable production of high-quality metabolomics datasets capturing isotopic flux. However, useful metabolic models can be difficult to derive due to the lack of relatively complete atom-resolved metabolic networks for a variety of organisms, including human. Here, we developed a neighborhood-specific graph coloring method that creates unique identifiers for each atom in a compound facilitating construction of an atom-resolved metabolic network. What is more, this method is guaranteed to generate the same identifier for symmetric atoms, enabling automatic identification of possible additional mappings caused by molecular symmetry. Furthermore, a compound coloring identifier derived from the corresponding atom coloring identifiers can be used for compound harmonization across various metabolic network databases, which is an essential first step in network integration. With the compound coloring identifiers, 8865 correspondences between KEGG (Kyoto Encyclopedia of Genes and Genomes) and MetaCyc compounds are detected, with 5451 of them confirmed by other identifiers provided by the two databases. In addition, we found that the Enzyme Commission numbers (EC) of reactions can be used to validate possible correspondence pairs, with 1848 unconfirmed pairs validated by commonality in reaction ECs. Moreover, we were able to detect various issues and errors with compound representation in KEGG and MetaCyc databases by compound coloring identifiers, demonstrating the usefulness of this methodology for database curation.
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137
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Muthusamy T, Cordes T, Handzlik MK, You L, Lim EW, Gengatharan J, Pinto AFM, Badur MG, Kolar MJ, Wallace M, Saghatelian A, Metallo CM. Serine restriction alters sphingolipid diversity to constrain tumour growth. Nature 2020; 586:790-795. [PMID: 32788725 PMCID: PMC7606299 DOI: 10.1038/s41586-020-2609-x] [Citation(s) in RCA: 147] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 05/11/2020] [Indexed: 11/22/2022]
Abstract
Serine, glycine, and other non-essential amino acids are critical for tumor progression, and strategies to limit their availability are emerging as potential cancer therapies1–3. However, the molecular mechanisms driving this response remain unclear, and the impact on lipid metabolism is relatively unexplored. Serine palmitoyltransferase (SPT) catalyzes the de novo biosynthesis of sphingolipids but also produces non-canonical 1-deoxysphingolipids (doxSLs) when using alanine as a substrate4,5. DoxSLs accumulate in the context of SPTLC1 or SPTLC2 mutations6,7 or low serine availability8,9 to drive neuropathy, and deoxysphinganine (doxSA) has been investigated as an anti-cancer agent10. Here we exploit amino acid metabolism and SPT promiscuity to modulate the endogenous synthesis of toxic doxSLs and slow tumor progression. Anchorage-independent growth reprograms a metabolic network involving serine, alanine, and pyruvate resulting in increased susceptibility to endogenous doxSL synthesis. Targeting the mitochondrial pyruvate carrier (MPC) promotes alanine oxidation to mitigate doxSL synthesis and improves spheroid growth, while direct inhibition of doxSL synthesis drives similar phenotypes. Restriction of dietary serine/glycine potently induces accumulation of doxSLs in xenografts while decreasing tumor growth. Pharmacological modulation of SPT rescues xenograft growth on serine/glycine-restricted diets, while reduction of circulating serine by inhibition of phosphoglycerate dehydrogenase (PHGDH) leads to doxSL accumulation and mitigates tumor growth. SPT promiscuity therefore links serine and mitochondrial alanine metabolism to membrane lipid diversity, which sensitizes tumors to metabolic stress.
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Affiliation(s)
| | - Thekla Cordes
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Michal K Handzlik
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Le You
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Esther W Lim
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Jivani Gengatharan
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Antonio F M Pinto
- Mass Spectrometry Core, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Mehmet G Badur
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Matthew J Kolar
- Clayton Foundation Laboratories for Peptide Biology, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Martina Wallace
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Alan Saghatelian
- Clayton Foundation Laboratories for Peptide Biology, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Christian M Metallo
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA. .,Moores Cancer Center, University of California, San Diego, La Jolla, CA, USA.
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138
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Application of Systems Engineering Principles and Techniques in Biological Big Data Analytics: A Review. Processes (Basel) 2020. [DOI: 10.3390/pr8080951] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In the past few decades, we have witnessed tremendous advancements in biology, life sciences and healthcare. These advancements are due in no small part to the big data made available by various high-throughput technologies, the ever-advancing computing power, and the algorithmic advancements in machine learning. Specifically, big data analytics such as statistical and machine learning has become an essential tool in these rapidly developing fields. As a result, the subject has drawn increased attention and many review papers have been published in just the past few years on the subject. Different from all existing reviews, this work focuses on the application of systems, engineering principles and techniques in addressing some of the common challenges in big data analytics for biological, biomedical and healthcare applications. Specifically, this review focuses on the following three key areas in biological big data analytics where systems engineering principles and techniques have been playing important roles: the principle of parsimony in addressing overfitting, the dynamic analysis of biological data, and the role of domain knowledge in biological data analytics.
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139
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Mechanism-based identification of plasma metabolites associated with liver toxicity. Toxicology 2020; 441:152493. [DOI: 10.1016/j.tox.2020.152493] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/01/2020] [Accepted: 05/08/2020] [Indexed: 12/25/2022]
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140
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Abstract
Metabolic flux analysis represents an essential perspective to understand cellular physiology and offers quantitative information to guide pathway engineering. A valuable approach for experimental elucidation of metabolic flux is dynamic flux analysis, which estimates the relative or absolute flow rates through a series of metabolic intermediates in a given pathway. It is based on kinetic isotope labeling experiments, liquid chromatography-mass spectrometry (LC-MS), and computational analysis that relate kinetic isotope trajectories of metabolites to pathway activity. Herein, we illustrate the mathematic principles underlying the dynamic flux analysis and mainly focus on describing the experimental procedures for data generation. This protocol is exemplified using cyanobacterial metabolism as an example, for which reliable labeling data for central carbon metabolites can be acquired quantitatively. This protocol is applicable to other microbial systems as well and can be readily adapted to address different metabolic processes.
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141
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Cheah YE, Xu Y, Sacco SA, Babele PK, Zheng AO, Johnson CH, Young JD. Systematic identification and elimination of flux bottlenecks in the aldehyde production pathway of Synechococcus elongatus PCC 7942. Metab Eng 2020; 60:56-65. [PMID: 32222320 PMCID: PMC7217728 DOI: 10.1016/j.ymben.2020.03.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 02/27/2020] [Accepted: 03/17/2020] [Indexed: 02/06/2023]
Abstract
Isotopically nonstationary metabolic flux analysis (INST-MFA) provides a versatile platform to quantitatively assess in vivo metabolic activities of autotrophic systems. By applying INST-MFA to recombinant aldehyde-producing cyanobacteria, we identified metabolic alterations that correlated with increased strain performance in order to guide rational metabolic engineering. We identified four reactions adjacent to the pyruvate node that varied significantly with increasing aldehyde production: pyruvate kinase (PK) and acetolactate synthase (ALS) fluxes were directly correlated with product formation, while pyruvate dehydrogenase (PDH) and phosphoenolpyruvate carboxylase (PPC) fluxes were inversely correlated. Overexpression of enzymes for PK or ALS did not result in further improvements to the previous best-performing strain, while downregulation of PDH expression (through antisense RNA expression) or PPC flux (through expression of the reverse reaction, phosphoenolpyruvate carboxykinase) provided significant improvements. These results illustrate the potential of INST-MFA to enable a systematic approach for iterative identification and removal of pathway bottlenecks in autotrophic host cells.
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Affiliation(s)
- Yi Ern Cheah
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA
| | - Yao Xu
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Sarah A Sacco
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA
| | - Piyoosh K Babele
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA
| | - Amy O Zheng
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA
| | - Carl Hirschie Johnson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Jamey D Young
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.
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142
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Tivendale ND, Hanson AD, Henry CS, Hegeman AD, Millar AH. Enzymes as Parts in Need of Replacement - and How to Extend Their Working Life. TRENDS IN PLANT SCIENCE 2020; 25:661-669. [PMID: 32526171 DOI: 10.1016/j.tplants.2020.02.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/11/2020] [Accepted: 02/14/2020] [Indexed: 06/11/2023]
Abstract
Enzymes catalyze reactions in vivo at different rates and each enzyme molecule has a lifetime limit before it is degraded and replaced to enable catalysis to continue. Considering these rates together as a unitless ratio of catalytic cycles until replacement (CCR) provides a new quantitative tool to assess the replacement schedule of and energy investment into enzymes as they relate to function. Here, we outline the challenges of determining CCRs and new approaches to overcome them and then assess the CCRs of selected enzymes in bacteria and plants to reveal a range of seven orders of magnitude for this ratio. Modifying CCRs in plants holds promise to lower cellular costs, to tailor enzymes for particular environments, and to breed enzyme improvements for crop productivity.
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Affiliation(s)
- Nathan D Tivendale
- ARC Centre for Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, M316, Perth, WA 6009, Australia
| | - Andrew D Hanson
- Horticultural Sciences Department, University of Florida, PO Box 110690, Gainesville, FL 32611-0690, USA
| | - Christopher S Henry
- Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL 60439, USA; Computation Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Adrian D Hegeman
- Department of Horticultural Science, Department of Plant and Microbial Biology, and The Microbial and Plant Genomics Institute, University of Minnesota, 1970 Folwell Avenue, Saint Paul, MN 55108-6007, USA
| | - A Harvey Millar
- ARC Centre for Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, M316, Perth, WA 6009, Australia.
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143
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Zhang Z, Liu Z, Meng Y, Chen Z, Han J, Wei Y, Shen T, Yi Y, Xie X. Parallel isotope differential modeling for instationary 13C fluxomics at the genome scale. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:103. [PMID: 32523616 PMCID: PMC7278083 DOI: 10.1186/s13068-020-01737-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 05/22/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND A precise map of the metabolic fluxome, the closest surrogate to the physiological phenotype, is becoming progressively more important in the metabolic engineering of photosynthetic organisms for biofuel and biomass production. For photosynthetic organisms, the state-of-the-art method for this purpose is instationary 13C fluxomics, which has arisen as a sibling of transcriptomics or proteomics. Instationary 13C data processing requires solving high-dimensional nonlinear differential equations and leads to large computational and time costs when its scope is expanded to a genome-scale metabolic network. RESULT Here, we present a parallelized method to model instationary 13C labeling data. The elementary metabolite unit (EMU) framework is reorganized to allow treating individual mass isotopomers and breaking up of their networks into strongly connected components (SCCs). A variable domain parallel algorithm is introduced to process ordinary differential equations in a parallel way. 15-fold acceleration is achieved for constant-step-size modeling and ~ fivefold acceleration for adaptive-step-size modeling. CONCLUSION This algorithm is universally applicable to isotope granules such as EMUs and cumomers and can substantially accelerate instationary 13C fluxomics modeling. It thus has great potential to be widely adopted in any instationary 13C fluxomics modeling.
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Affiliation(s)
- Zhengdong Zhang
- College of Mathematics and Information Science, Guiyang University, Guiyang, Guizhou China
- Key Laboratory of Information and Computing Science Guizhou Province, Guizhou Normal University, Guiyang, Guizhou China
| | - Zhentao Liu
- College of Computer Science and Technology, Guizhou University, Guiyang, Guizhou China
| | - Yafei Meng
- College of Mathematics and Information Science, Guiyang University, Guiyang, Guizhou China
| | - Zhen Chen
- School of Mathematics and Sciences, Guizhou Normal University, Guiyang, Guizhou China
| | - Jiayu Han
- School of Mathematics and Sciences, Guizhou Normal University, Guiyang, Guizhou China
| | - Yimin Wei
- School of Mathematics Sciences and Key Laboratory of Mathematics for Nonlinear Sciences, Fudan University, Shanghai, China
| | - Tie Shen
- Key Laboratory of Information and Computing Science Guizhou Province, Guizhou Normal University, Guiyang, Guizhou China
| | - Yin Yi
- College of Life Science, Guizhou Normal University, Guiyang, Guizhou China
| | - Xiaoyao Xie
- Key Laboratory of Information and Computing Science Guizhou Province, Guizhou Normal University, Guiyang, Guizhou China
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144
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Im D, Hong J, Gu B, Sung C, Oh M. 13
C Metabolic Flux Analysis of
Escherichia coli
Engineered for Gamma‐Aminobutyrate Production. Biotechnol J 2020; 15:e1900346. [DOI: 10.1002/biot.201900346] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 04/12/2020] [Indexed: 12/28/2022]
Affiliation(s)
- Dae‐Kyun Im
- Department of Chemical and Biological EngineeringKorea University 145 Anam‐ro, Seongbuk‐gu Seoul 02841 Korea
| | - Jaeseung Hong
- Department of Chemical and Biological EngineeringKorea University 145 Anam‐ro, Seongbuk‐gu Seoul 02841 Korea
| | - Boncheol Gu
- Department of Chemical and Biological EngineeringKorea University 145 Anam‐ro, Seongbuk‐gu Seoul 02841 Korea
| | - Changmin Sung
- Doping Control CenterKorea Institute of Science and Technology 5 Hwarang‐ro 14‐gil, Seongbuk‐gu Seoul 02792 Korea
| | - Min‐Kyu Oh
- Department of Chemical and Biological EngineeringKorea University 145 Anam‐ro, Seongbuk‐gu Seoul 02841 Korea
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145
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Boland ML, Laker RC, Mather K, Nawrocki A, Oldham S, Boland BB, Lewis H, Conway J, Naylor J, Guionaud S, Feigh M, Veidal SS, Lantier L, McGuinness OP, Grimsby J, Rondinone CM, Jermutus L, Larsen MR, Trevaskis JL, Rhodes CJ. Resolution of NASH and hepatic fibrosis by the GLP-1R/GcgR dual-agonist Cotadutide via modulating mitochondrial function and lipogenesis. Nat Metab 2020; 2:413-431. [PMID: 32478287 PMCID: PMC7258337 DOI: 10.1038/s42255-020-0209-6] [Citation(s) in RCA: 126] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Non-alcoholic fatty liver disease and steatohepatitis are highly associated with obesity and type 2 diabetes mellitus. Cotadutide, a GLP-1R/GcgR agonist, was shown to reduce blood glycemia, body weight and hepatic steatosis in patients with T2DM. Here, we demonstrate that the effects of Cotadutide to reduce body weight, food intake and improve glucose control are predominantly mediated through the GLP-1 signaling, while, its action on the liver to reduce lipid content, drive glycogen flux and improve mitochondrial turnover and function are directly mediated through Gcg signaling. This was confirmed by the identification of phosphorylation sites on key lipogenic and glucose metabolism enzymes in liver of mice treated with Cotadutide. Complementary metabolomic and transcriptomic analyses implicated lipogenic, fibrotic and inflammatory pathways, which are consistent with a unique therapeutic contribution of GcgR agonism by Cotadutide in vivo. Significantly, Cotadutide also alleviated fibrosis to a greater extent than Liraglutide or Obeticholic acid (OCA), despite adjusting dose to achieve similar weight loss in 2 preclinical mouse models of NASH. Thus Cotadutide, via direct hepatic (GcgR) and extra-hepatic (GLP-1R) effects, exerts multi-factorial improvement in liver function and is a promising therapeutic option for the treatment of steatohepatitis.
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Affiliation(s)
- Michelle L Boland
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA
| | - Rhianna C Laker
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA
| | - Karly Mather
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA
| | - Arkadiusz Nawrocki
- Department of Biochemistry and Molecular Biology, PR group, University of Southern Denmark, Odense, Denmark
| | - Stephanie Oldham
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA
| | - Brandon B Boland
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA
| | - Hilary Lewis
- Research and Early Development, Oncology, AstraZeneca, Cambridge, UK
| | - James Conway
- Translational Sciences, AstraZeneca, Gaithersburg, MD, USA
| | - Jacqueline Naylor
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | | | | | | | - Louise Lantier
- Vanderbilt University Mouse Metabolic Phenotyping Center, Nashville, TN, USA
| | - Owen P McGuinness
- Vanderbilt University Mouse Metabolic Phenotyping Center, Nashville, TN, USA
| | - Joseph Grimsby
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA
| | - Cristina M Rondinone
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA
| | - Lutz Jermutus
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Martin R Larsen
- Department of Biochemistry and Molecular Biology, PR group, University of Southern Denmark, Odense, Denmark
| | - James L Trevaskis
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA
- Gilead Sciences, Foster City, CA, USA
| | - Christopher J Rhodes
- Research and Early Development, Cardiovascular, Renal and Metabolic Diseases, BioPharmaceuticals R&D, AstraZeneca, Gaithersburg, MD, USA.
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Lesner NP, Gokhale AS, Kota K, DeBerardinis RJ, Mishra P. α-ketobutyrate links alterations in cystine metabolism to glucose oxidation in mtDNA mutant cells. Metab Eng 2020; 60:157-167. [PMID: 32330654 PMCID: PMC7310915 DOI: 10.1016/j.ymben.2020.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 03/04/2020] [Accepted: 03/24/2020] [Indexed: 11/08/2022]
Abstract
Pathogenic mutations in the mitochondrial genome (mtDNA) impair organellar ATP production, requiring mutant cells to activate metabolic adaptations for survival. Understanding how metabolism adapts to clinically relevant mtDNA mutations may provide insight into cellular strategies for metabolic flexibility. In this study, we use 13C isotope tracing and metabolic flux analysis to investigate central carbon and amino acid metabolic reprogramming in isogenic cells containing mtDNA mutations. We identify alterations in glutamine and cystine transport which indirectly regulate mitochondrial metabolism and electron transport chain function. Metabolism of cystine can promote glucose oxidation through the transsulfuration pathway and the production of α-ketobutyrate. Intriguingly, activating or inhibiting α-ketobutyrate production is sufficient to modulate both glucose oxidation and mitochondrial respiration in mtDNA mutant cells. Thus, cystine-stimulated transsulfuration serves as an adaptive mechanism linking glucose oxidation and amino acid metabolism in the setting of mtDNA mutations.
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Affiliation(s)
- Nicholas P Lesner
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Amrita S Gokhale
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Kalyani Kota
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Ralph J DeBerardinis
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA; Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Prashant Mishra
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA; Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA; Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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147
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Millard P, Schmitt U, Kiefer P, Vorholt JA, Heux S, Portais JC. ScalaFlux: A scalable approach to quantify fluxes in metabolic subnetworks. PLoS Comput Biol 2020; 16:e1007799. [PMID: 32287281 PMCID: PMC7182278 DOI: 10.1371/journal.pcbi.1007799] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 04/24/2020] [Accepted: 03/19/2020] [Indexed: 01/01/2023] Open
Abstract
13C-metabolic flux analysis (13C-MFA) allows metabolic fluxes to be quantified in living organisms and is a major tool in biotechnology and systems biology. Current 13C-MFA approaches model label propagation starting from the extracellular 13C-labeled nutrient(s), which limits their applicability to the analysis of pathways close to this metabolic entry point. Here, we propose a new approach to quantify fluxes through any metabolic subnetwork of interest by modeling label propagation directly from the metabolic precursor(s) of this subnetwork. The flux calculations are thus purely based on information from within the subnetwork of interest, and no additional knowledge about the surrounding network (such as atom transitions in upstream reactions or the labeling of the extracellular nutrient) is required. This approach, termed ScalaFlux for SCALAble metabolic FLUX analysis, can be scaled up from individual reactions to pathways to sets of pathways. ScalaFlux has several benefits compared with current 13C-MFA approaches: greater network coverage, lower data requirements, independence from cell physiology, robustness to gaps in data and network information, better computational efficiency, applicability to rich media, and enhanced flux identifiability. We validated ScalaFlux using a theoretical network and simulated data. We also used the approach to quantify fluxes through the prenyl pyrophosphate pathway of Saccharomyces cerevisiae mutants engineered to produce phytoene, using a dataset for which fluxes could not be calculated using existing approaches. A broad range of metabolic systems can be targeted with minimal cost and effort, making ScalaFlux a valuable tool for the analysis of metabolic fluxes.
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Affiliation(s)
- Pierre Millard
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
| | - Uwe Schmitt
- Scientific IT Services, ETH Zurich, Zurich, Switzerland
| | - Patrick Kiefer
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Julia A. Vorholt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Stéphanie Heux
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
| | - Jean-Charles Portais
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
- MetaboHUB-MetaToul, National infrastructure of metabolomics and fluxomics, Toulouse, France
- STROMALab, Université de Toulouse, INSERM U1031, EFS, INP-ENVT, UPS, Toulouse, France
- * E-mail:
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148
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Cystine transporter regulation of pentose phosphate pathway dependency and disulfide stress exposes a targetable metabolic vulnerability in cancer. Nat Cell Biol 2020; 22:476-486. [PMID: 32231310 PMCID: PMC7194135 DOI: 10.1038/s41556-020-0496-x] [Citation(s) in RCA: 240] [Impact Index Per Article: 60.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 02/28/2020] [Indexed: 02/06/2023]
Abstract
SLC7A11-mediated cystine uptake is critical for maintaining redox balance and cell survival. Here, we show that this comes at a significant cost for cancer cells with high SLC7A11 expression. Actively importing cystine is potentially toxic due to its low solubility, forcing SLC7A11-high cancer cells to constitutively reduce cystine to the more soluble cysteine. This presents a substantial drain on the cellular NADPH pool and renders such cells dependent on the pentose phosphate pathway (PPP). Limiting glucose supply to SLC7A11-high cancer cells results in marked accumulation of intracellular cystine, redox system collapse, and rapid cell death, which can be rescued by treatments that prevent disulfide accumulation. We further show that glucose transporter (GLUT) inhibitors selectively kill SLC7A11-high cancer cells and suppress SLC7A11-high tumor growth. Our results identify a coupling between SLC7A11-associated cystine metabolism and the PPP, and uncover an accompanying metabolic vulnerability for therapeutic targeting in SLC7A11-high cancers.
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149
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Robust Moiety Model Selection Using Mass Spectrometry Measured Isotopologues. Metabolites 2020; 10:metabo10030118. [PMID: 32245221 PMCID: PMC7143054 DOI: 10.3390/metabo10030118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/14/2020] [Accepted: 03/19/2020] [Indexed: 11/18/2022] Open
Abstract
Stable isotope resolved metabolomics (SIRM) experiments use stable isotope tracers to provide superior metabolomics datasets for metabolic flux analysis and metabolic modeling. Since assumptions of model correctness can seriously compromise interpretation of metabolic flux results, we have developed a metabolic modeling software package specifically designed for moiety model comparison and selection based on the metabolomics data provided. Here, we tested the effectiveness of model selection with two time-series mass spectrometry (MS) isotopologue datasets for uridine diphosphate N-acetyl-d-glucosamine (UDP-GlcNAc) generated from different platforms utilizing direct infusion nanoelectrospray and liquid chromatography. Analysis results demonstrate the robustness of our model selection methods by the successful selection of the optimal model from over 40 models provided. Moreover, the effects of specific optimization methods, degree of optimization, selection criteria, and specific objective functions on model selection are illustrated. Overall, these results indicate that over-optimization can lead to model selection failure, but combining multiple datasets can help control this overfitting effect. The implication is that SIRM datasets in public repositories of reasonable quality can be combined with newly acquired datasets to improve model selection. Furthermore, curation efforts of public metabolomics repositories to maintain high data quality could have a huge impact on future metabolic modeling efforts.
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150
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In Vivo Thermodynamic Analysis of Glycolysis in Clostridium thermocellum and Thermoanaerobacterium saccharolyticum Using 13C and 2H Tracers. mSystems 2020; 5:5/2/e00736-19. [PMID: 32184362 PMCID: PMC7380578 DOI: 10.1128/msystems.00736-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Thermodynamics constitutes a key determinant of flux and enzyme efficiency in metabolic networks. Here, we provide new insights into the divergent thermodynamics of the glycolytic pathways of C. thermocellum and T. saccharolyticum, two industrially relevant thermophilic bacteria whose metabolism still is not well understood. We report that while the glycolytic pathway in T. saccharolyticum is as thermodynamically favorable as that found in model organisms, such as E. coli or Saccharomyces cerevisiae, the glycolytic pathway of C. thermocellum operates near equilibrium. The use of a near-equilibrium glycolytic pathway, with potentially increased ATP yield, by this cellulolytic microbe may represent an evolutionary adaptation to growth on cellulose, but it has the drawback of being highly susceptible to product feedback inhibition. The results of this study will facilitate future engineering of high-performance strains capable of transforming cellulosic biomass to biofuels at high yields and titers. Clostridium thermocellum and Thermoanaerobacterium saccharolyticum are thermophilic anaerobic bacteria with complementary metabolic capabilities that utilize distinct glycolytic pathways for the conversion of cellulosic sugars to biofuels. We integrated quantitative metabolomics with 2H and 13C metabolic flux analysis to investigate the in vivo reversibility and thermodynamics of the central metabolic networks of these two microbes. We found that the glycolytic pathway in C. thermocellum operates remarkably close to thermodynamic equilibrium, with an overall drop in Gibbs free energy 5-fold lower than that of T. saccharolyticum or anaerobically grown Escherichia coli. The limited thermodynamic driving force of glycolysis in C. thermocellum could be attributed in large part to the small free energy of the phosphofructokinase reaction producing fructose bisphosphate. The ethanol fermentation pathway was also substantially more reversible in C. thermocellum than in T. saccharolyticum. These observations help explain the comparatively low ethanol titers of C. thermocellum and suggest engineering interventions that can be used to increase its ethanol productivity and glycolytic rate. In addition to thermodynamic analysis, we used our isotope tracer data to reconstruct the T. saccharolyticum central metabolic network, revealing exclusive use of the Embden-Meyerhof-Parnas (EMP) pathway for glycolysis, a bifurcated tricarboxylic acid (TCA) cycle, and a sedoheptulose bisphosphate bypass active within the pentose phosphate pathway. IMPORTANCE Thermodynamics constitutes a key determinant of flux and enzyme efficiency in metabolic networks. Here, we provide new insights into the divergent thermodynamics of the glycolytic pathways of C. thermocellum and T. saccharolyticum, two industrially relevant thermophilic bacteria whose metabolism still is not well understood. We report that while the glycolytic pathway in T. saccharolyticum is as thermodynamically favorable as that found in model organisms, such as E. coli or Saccharomyces cerevisiae, the glycolytic pathway of C. thermocellum operates near equilibrium. The use of a near-equilibrium glycolytic pathway, with potentially increased ATP yield, by this cellulolytic microbe may represent an evolutionary adaptation to growth on cellulose, but it has the drawback of being highly susceptible to product feedback inhibition. The results of this study will facilitate future engineering of high-performance strains capable of transforming cellulosic biomass to biofuels at high yields and titers.
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