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Panten U, Brüning D, Rustenbeck I. Regulation of insulin secretion in mouse islets: metabolic amplification by alpha-ketoisocaproate coincides with rapid and sustained increase in acetyl-CoA content. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2023; 396:353-364. [PMID: 36355207 PMCID: PMC9832085 DOI: 10.1007/s00210-022-02290-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 09/05/2022] [Indexed: 11/12/2022]
Abstract
Glucose and alpha-ketoisocaproate, the keto acid analogue of leucine, stimulate insulin secretion in the absence of other exogenous fuels. Their mitochondrial metabolism in the beta-cell raises the cytosolic ATP/ADP ratio, thereby providing the triggering signal for the exocytosis of the insulin granules. However, additional amplifying signals are required for the full extent of insulin secretion stimulated by these fuels. While it is generally recognized that the amplifying signals are also derived from the mitochondrial metabolism, their exact nature is still unclear. The current study tests the hypothesis that the supply of cytosolic acetyl-CoA is a signal in the amplifying pathway. The contents of acetyl-CoA and acetyl-CoA plus CoA-SH were measured in isolated mouse islets. Insulin secretion was recorded in isolated perifused islets. In islets, the ATP-sensitive K+ channels of which were pharmacologically closed and which were preincubated without exogenous fuel, 10 mmol/L alpha-ketoisocaproate enhanced the acetyl-CoA content after 5 and 20 min incubations and decreased the acetyl-CoA plus CoA-SH within 5 min, but not after 20 min. In islets not exposed to drugs, the preincubation with 3 mmol/L glucose, a non-triggering concentration, elevated the acetyl-CoA content. This content was further increased after 5 min and 20 min incubations with 30 mmol/L glucose, concurrent with a strong increase in insulin secretion. Alpha-ketoisocaproate and glucose increase the supply of acetyl-CoA in the beta-cell cytosol during both phases of insulin secretion. Most likely, this increase provides a signal for the metabolic amplification.
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Affiliation(s)
- Uwe Panten
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Mendelssohnstr. 1, 38106 Braunschweig, Germany
| | - Dennis Brüning
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Mendelssohnstr. 1, 38106 Braunschweig, Germany
| | - Ingo Rustenbeck
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, Mendelssohnstr. 1, 38106 Braunschweig, Germany
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Vanweert F, Schrauwen P, Phielix E. Role of branched-chain amino acid metabolism in the pathogenesis of obesity and type 2 diabetes-related metabolic disturbances BCAA metabolism in type 2 diabetes. Nutr Diabetes 2022; 12:35. [PMID: 35931683 PMCID: PMC9356071 DOI: 10.1038/s41387-022-00213-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 06/15/2022] [Accepted: 07/05/2022] [Indexed: 12/23/2022] Open
Abstract
Branched-chain amino acid (BCAA) catabolism has been considered to have an emerging role in the pathogenesis of metabolic disturbances in obesity and type 2 diabetes (T2D). Several studies showed elevated plasma BCAA levels in humans with insulin resistance and patients with T2D, although the underlying reason is unknown. Dysfunctional BCAA catabolism could theoretically be an underlying factor. In vitro and animal work collectively show that modulation of the BCAA catabolic pathway alters key metabolic processes affecting glucose homeostasis, although an integrated understanding of tissue-specific BCAA catabolism remains largely unknown, especially in humans. Proof-of-concept studies in rodents -and to a lesser extent in humans – strongly suggest that enhancing BCAA catabolism improves glucose homeostasis in metabolic disorders, such as obesity and T2D. In this review, we discuss several hypothesized mechanistic links between BCAA catabolism and insulin resistance and overview current available tools to modulate BCAA catabolism in vivo. Furthermore, this review considers whether enhancing BCAA catabolism forms a potential future treatment strategy to promote metabolic health in insulin resistance and T2D.
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Affiliation(s)
- Froukje Vanweert
- Department of Nutrition and Movement Sciences, NUTRIM, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Patrick Schrauwen
- Department of Nutrition and Movement Sciences, NUTRIM, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Esther Phielix
- Department of Nutrition and Movement Sciences, NUTRIM, School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands.
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Hu W, Yang P, Fu Z, Wang Y, Zhou Y, Ye Z, Gong Y, Huang A, Sun L, Zhao Y, Yang T, Li Z, Jiang XC, Yu W, Zhou H. High L-Valine Concentrations Associate with Increased Oxidative Stress and Newly-Diagnosed Type 2 Diabetes Mellitus: A Cross-Sectional Study. Diabetes Metab Syndr Obes 2022; 15:499-509. [PMID: 35221701 PMCID: PMC8865866 DOI: 10.2147/dmso.s336736] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/14/2022] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Branched-chain amino acids (BCAAs) are essential AAs which are widely used as antioxidants in patients with liver and kidney dysfunction. However, BCAAs are strongly correlated with insulin resistance (IR) and diabetes. This study aimed to evaluate the relationship among BCAAs, oxidative stress, and type 2 diabetes mellitus (T2DM) in a Chinese population. METHODS Anthropometric and biochemical examinations were performed in 816 individuals who participated in the Huai'an Diabetes Prevention Program. Serum BCAAs concentrations were measured by hydrophilic interaction chromatography-tandem mass spectrometric method. Oxidative stress was evaluated by malondialdehyde (MDA) as an index of lipid peroxidation and the superoxide dismutase (SOD) activity. RESULTS A total of 816 participants were divided into three groups: normal glucose metabolism (NGM), prediabetes, and newly-diagnosed diabetes mellitus (NDM). Subjects in NDM group show higher MDA and lower SOD levels than subjects in other groups. L-Val levels positively correlated with MDA levels and negatively with SOD in NDM groups. After adjusting for T2DM risk factors, high L-Val levels were significantly associated with higher BMI, WC, FPG, increased LnTG and decreased HDL-C. L-Val was also independently associated with NDM (OR 1.06, 95% CI 1.02-1.10; P = 0.005). Furthermore, the odds ratios for NDM among participants with high L-Val (≥35.25μg/mL) levels showed a 2.25-fold (95% CI 1.11-4.57; P = 0.024) increase compared to participants with low L-Val (<27.26 μg/mL) levels after adjusting for MDA and confounding factors. CONCLUSION High serum L-Val levels are independently associated with oxidative stress, thus promoting IR and NDM. Further study should be done to clarify the mechanism.
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Affiliation(s)
- Wen Hu
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
- Department of Endocrinology and Metabolism, The Affiliated Huai’an Hospital of Xuzhou Medical College, Huai’an, Jiangsu, People’s Republic of China
| | - Panpan Yang
- Department of Respiratory Diseases, The Affiliated Huai’an Hospital of Xuzhou Medical College, Huai’an, Jiangsu, People’s Republic of China
| | - Zhenzhen Fu
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Yongqing Wang
- Research Division of Clinical Pharmacology, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Ying Zhou
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Zhengqin Ye
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Yingyun Gong
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Aijie Huang
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Luning Sun
- Research Division of Clinical Pharmacology, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Yang Zhao
- School of Public Health Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Tao Yang
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Zhong Li
- Key Laboratory of Rare Metabolic Diseases, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
- Jiangsu Province Key Laboratory of Human Functional Genomics, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Xian-Cheng Jiang
- Department of Anatomy and Cell Biology, State University of New York Downstate Medical Center, Brooklyn, NY, USA
| | - Weinan Yu
- Department of Endocrinology and Metabolism, The Affiliated Huai’an Hospital of Xuzhou Medical College, Huai’an, Jiangsu, People’s Republic of China
- Weinan Yu, Department of Endocrinology and Metabolism, Huai’an Hospital Affiliated to Xuzhou Medical University and Huai’an Second People’s Hospital, Huai’an, 223001, People’s Republic of China, Email
| | - Hongwen Zhou
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
- Key Laboratory of Rare Metabolic Diseases, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
- Correspondence: Hongwen Zhou, Department of endocrinology, The First Affiliated Hospital, Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu, 210029, People’s Republic of China, Tel +862583718836-6893, Fax +862583781781, Email
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Roberts JA, Varma VR, Huang CW, An Y, Oommen A, Tanaka T, Ferrucci L, Elango P, Takebayashi T, Harada S, Iida M, Thambisetty M. Blood Metabolite Signature of Metabolic Syndrome Implicates Alterations in Amino Acid Metabolism: Findings from the Baltimore Longitudinal Study of Aging (BLSA) and the Tsuruoka Metabolomics Cohort Study (TMCS). Int J Mol Sci 2020; 21:E1249. [PMID: 32070008 PMCID: PMC7072861 DOI: 10.3390/ijms21041249] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/07/2020] [Accepted: 02/10/2020] [Indexed: 12/12/2022] Open
Abstract
Rapid lifestyle and dietary changes have contributed to a rise in the global prevalence of metabolic syndrome (MetS), which presents a potential healthcare crisis, owing to its association with an increased burden of multiple cardiovascular and neurological diseases. Prior work has identified the role that genetic, lifestyle, and environmental factors can play in the prevalence of MetS. Metabolomics is an important tool to study alterations in biochemical pathways intrinsic to the pathophysiology of MetS. We undertook a metabolomic study of MetS in serum samples from two ethnically distinct, well-characterized cohorts-the Baltimore Longitudinal Study of Aging (BLSA) from the U.S. and the Tsuruoka Metabolomics Cohort Study (TMCS) from Japan. We used multivariate logistic regression to identify metabolites that were associated with MetS in both cohorts. Among the top 25 most significant (lowest p-value) metabolite associations with MetS in each cohort, we identified 18 metabolites that were shared between TMCS and BLSA, the majority of which were classified as amino acids. These associations implicate multiple biochemical pathways in MetS, including branched-chain amino acid metabolism, glutathione production, aromatic amino acid metabolism, gluconeogenesis, and the tricarboxylic acid cycle. Our results suggest that fundamental alterations in amino acid metabolism may be central features of MetS.
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Affiliation(s)
- Jackson A. Roberts
- Clinical and Translational Neuroscience Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA; (J.A.R.); (V.R.V.)
| | - Vijay R. Varma
- Clinical and Translational Neuroscience Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA; (J.A.R.); (V.R.V.)
| | - Chiung-Wei Huang
- Brain Aging and Behavior Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA; (C.-W.H.); (Y.A.)
| | - Yang An
- Brain Aging and Behavior Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA; (C.-W.H.); (Y.A.)
| | - Anup Oommen
- Glycoscience Group, National Centre for Biomedical Engineering Science, National University of Ireland Galway, Galway H91-TK33, Ireland;
| | - Toshiko Tanaka
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA; (T.T.); (L.F.); (P.E.)
| | - Luigi Ferrucci
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA; (T.T.); (L.F.); (P.E.)
| | - Palchamy Elango
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA; (T.T.); (L.F.); (P.E.)
| | - Toru Takebayashi
- Department of Preventive Medicine and Public Health, Keio University, Tokyo 160-8282, Japan; (T.T.); (S.H.); (M.I.)
| | - Sei Harada
- Department of Preventive Medicine and Public Health, Keio University, Tokyo 160-8282, Japan; (T.T.); (S.H.); (M.I.)
| | - Miho Iida
- Department of Preventive Medicine and Public Health, Keio University, Tokyo 160-8282, Japan; (T.T.); (S.H.); (M.I.)
| | - Madhav Thambisetty
- Clinical and Translational Neuroscience Section, Laboratory of Behavioral Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA; (J.A.R.); (V.R.V.)
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Zeng Y, Mtintsilana A, Goedecke JH, Micklesfield LK, Olsson T, Chorell E. Alterations in the metabolism of phospholipids, bile acids and branched-chain amino acids predicts development of type 2 diabetes in black South African women: a prospective cohort study. Metabolism 2019; 95:57-64. [PMID: 30954560 DOI: 10.1016/j.metabol.2019.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/12/2019] [Accepted: 04/01/2019] [Indexed: 01/04/2023]
Abstract
BACKGROUND South Africa (SA) has the highest global projected increase in diabetes risk. Factors typically associated with insulin resistance and type 2 diabetes risk in Caucasians are not significant correlates in black African populations. Therefore, we aimed to identify circulating metabolite patterns that predict type 2 diabetes development in this high-risk, yet understudied SA population. METHODS We conducted a prospective cohort study in black SA women with normal glucose tolerance (NGT). Participants were followed for 13 years and developed (i) type 2 diabetes (n = 20, NGT-T2D), (ii) impaired glucose tolerance (IGT) (n = 27, NGT-IGT), or (iii) remained NGT (n = 28, NGT-NGT). Mass-spectrometry based metabolomics and multivariate analyses were used to elucidate metabolite patterns at baseline and at follow-up that were associated with type 2 diabetes development. RESULTS Metabolites of phospholipid, bile acid and branched-chain amino acid (BCAA) metabolism, differed significantly between the NGT-T2D and NGT-NGT groups. At baseline: the NGT-T2D group had i) a higher lysophosphatidylcholine:lysophosphatidylethanolamine ratio containing linoleic acid (LPC(C18:2):LPE(C18:2)), ii) lower proliferation-related bile acids (ursodeoxycholic- and chenodeoxycholic acid), iii) higher levels of leucine and its catabolic intermediates (ketoleucine and C5-carnitine), compared to the NGT-NGT group. At follow-up: the NGT-T2D group had i) lower LPC(C18:2) levels, ii) higher apoptosis-related bile acids (deoxycholic- and glycodeoxycholic acid), and iii) higher levels of all BCAAs and their catabolic intermediates. CONCLUSIONS Changes in lysophospholipid metabolism and the bile acid pool occur during the development of type 2 diabetes in black South African women. Further, impaired leucine catabolism precedes valine and isoleucine catabolism in the development of type 2 diabetes. These metabolite patterns can be useful to identify and monitor type 2 diabetes risk >10 years prior to disease onset and provide insight into the pathophysiology of type 2 diabetes in this high risk, but under-studied population.
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Affiliation(s)
- Yingxu Zeng
- Department of Public Health and Clinical Medicine, Umeå University, Sweden
| | - Asanda Mtintsilana
- MRC/Wits Developmental Pathways for Health Research Unit, Department of Paediatrics, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Julia H Goedecke
- MRC/Wits Developmental Pathways for Health Research Unit, Department of Paediatrics, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa; Non-Communicable Diseases Research Unit, South African Medical Research Council, Cape Town, South Africa
| | - Lisa K Micklesfield
- MRC/Wits Developmental Pathways for Health Research Unit, Department of Paediatrics, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Tommy Olsson
- Department of Public Health and Clinical Medicine, Umeå University, Sweden
| | - Elin Chorell
- Department of Public Health and Clinical Medicine, Umeå University, Sweden.
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Gancheva S, Jelenik T, Álvarez-Hernández E, Roden M. Interorgan Metabolic Crosstalk in Human Insulin Resistance. Physiol Rev 2018; 98:1371-1415. [PMID: 29767564 DOI: 10.1152/physrev.00015.2017] [Citation(s) in RCA: 122] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Excessive energy intake and reduced energy expenditure drive the development of insulin resistance and metabolic diseases such as obesity and type 2 diabetes mellitus. Metabolic signals derived from dietary intake or secreted from adipose tissue, gut, and liver contribute to energy homeostasis. Recent metabolomic studies identified novel metabolites and enlarged our knowledge on classic metabolites. This review summarizes the evidence of their roles as mediators of interorgan crosstalk and regulators of insulin sensitivity and energy metabolism. Circulating lipids such as free fatty acids, acetate, and palmitoleate from adipose tissue and short-chain fatty acids from the gut effectively act on liver and skeletal muscle. Intracellular lipids such as diacylglycerols and sphingolipids can serve as lipotoxins by directly inhibiting insulin action in muscle and liver. In contrast, fatty acid esters of hydroxy fatty acids have been recently shown to exert a series of beneficial effects. Also, ketoacids are gaining interest as potent modulators of insulin action and mitochondrial function. Finally, branched-chain amino acids not only predict metabolic diseases, but also inhibit insulin signaling. Here, we focus on the metabolic crosstalk in humans, which regulates insulin sensitivity and energy homeostasis in the main insulin-sensitive tissues, skeletal muscle, liver, and adipose tissue.
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Affiliation(s)
- Sofiya Gancheva
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University , Düsseldorf , Germany ; Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University , Düsseldorf , Germany ; and German Center of Diabetes Research (DZD e.V.), Munich- Neuherberg , Germany
| | - Tomas Jelenik
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University , Düsseldorf , Germany ; Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University , Düsseldorf , Germany ; and German Center of Diabetes Research (DZD e.V.), Munich- Neuherberg , Germany
| | - Elisa Álvarez-Hernández
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University , Düsseldorf , Germany ; Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University , Düsseldorf , Germany ; and German Center of Diabetes Research (DZD e.V.), Munich- Neuherberg , Germany
| | - Michael Roden
- Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University , Düsseldorf , Germany ; Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University , Düsseldorf , Germany ; and German Center of Diabetes Research (DZD e.V.), Munich- Neuherberg , Germany
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Pietzner M, Budde K, Homuth G, Kastenmüller G, Henning AK, Artati A, Krumsiek J, Völzke H, Adamski J, Lerch MM, Kühn JP, Nauck M, Friedrich N. Hepatic Steatosis Is Associated With Adverse Molecular Signatures in Subjects Without Diabetes. J Clin Endocrinol Metab 2018; 103:3856-3868. [PMID: 30060179 DOI: 10.1210/jc.2018-00999] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/24/2018] [Indexed: 01/14/2023]
Abstract
BACKGROUND AND AIMS Exaggerated hepatic triglyceride accumulation (i.e., hepatic steatosis) represents a strong risk factor for type 2 diabetes mellitus and cardiovascular disease. Despite the clear association of hepatic steatosis with impaired insulin signaling, the precise molecular mechanisms involved are still under debate. We combined data from several metabolomics techniques to gain a comprehensive picture of molecular alterations related to the presence of hepatic steatosis in a diabetes-free sample (N = 769) of the population-based Study of Health in Pomerania. METHODS Liver fat content (LFC) was assessed using MRI. Metabolome measurements of plasma and urine samples were done by mass spectrometry and nuclear magnetic resonance spectroscopy. Linear regression analyses were used to detect significant associations with either LFC or markers of hepatic damage. Possible mediations through insulin resistance, hypertriglyceridemia, and inflammation were tested. A predictive molecular signature of hepatic steatosis was established using regularized logistic regression. RESULTS The LFC-associated atherogenic lipid profile, tightly connected to shifts in the phospholipid content, and a prediabetic amino acid cluster were mediated by insulin resistance. Molecular surrogates of oxidative stress and multiple associations with urine metabolites (e.g., indicating altered cortisol metabolism or phase II detoxification products) were unaffected in mediation analyses. Incorporation of urine metabolites slightly improved classification of hepatic steatosis. CONCLUSIONS Comprehensive metabolic profiling allowed us to reveal molecular patterns accompanying hepatic steatosis independent of the known hallmarks. Novel biomarkers from urine (e.g., cortisol glucuronide) are worthwhile for follow-up in patients suffering from more severe liver impairment compared with our merely healthy population-based sample.
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Affiliation(s)
- Maik Pietzner
- Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald, Greifswald, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Greifswald, Greifswald, Germany
| | - Kathrin Budde
- Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald, Greifswald, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Greifswald, Greifswald, Germany
| | - Georg Homuth
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine and University Greifswald, Greifswald, Germany
| | - Gabi Kastenmüller
- Institute of Bioinformatics and Systems Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Ann-Kristin Henning
- Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Anna Artati
- Institute of Experimental Genetics, Genome Analysis Center, Helmholtz Zentrum München, Neuherberg, Germany
| | - Jan Krumsiek
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Henry Völzke
- German Center for Cardiovascular Research (DZHK), Partner Site Greifswald, Greifswald, Germany
- Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany
- German Center for Diabetes Research (DZD), Site Greifswald, Greifswald, Germany
| | - Jerzy Adamski
- Institute of Experimental Genetics, Genome Analysis Center, Helmholtz Zentrum München, Neuherberg, Germany
- German Center for Diabetes Research (DZD), Site Greifswald, Greifswald, Germany
- Lehrstuhl für Experimentelle Genetik, Technische Universität München, Freising-Weihenstephan, Germany
| | - Markus M Lerch
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Jens P Kühn
- Institute of Diagnostic Radiology and Neuroradiology, University Medicine Greifswald, Greifswald, Germany
- Institute of Diagnostic Radiology, University Medicine, Carl Gustav Carus University, Dresden, Germany
| | - Matthias Nauck
- Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald, Greifswald, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Greifswald, Greifswald, Germany
| | - Nele Friedrich
- Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald, Greifswald, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Greifswald, Greifswald, Germany
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A. R, Agrawal N, Kumar H, Kumar V. Emerging role of branched chain amino acids in metabolic disorders: A mechanistic review. PHARMANUTRITION 2018. [DOI: 10.1016/j.phanu.2018.01.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Panten U, Früh E, Reckers K, Rustenbeck I. Acute metabolic amplification of insulin secretion in mouse islets: Role of cytosolic acetyl-CoA. Metabolism 2016; 65:1225-9. [PMID: 27506729 DOI: 10.1016/j.metabol.2016.05.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 04/20/2016] [Accepted: 05/05/2016] [Indexed: 01/10/2023]
Abstract
OBJECTIVE Stimulation of the ß-cell metabolism by glucose and other fuels triggers insulin release by enhancing the mitochondrial ATP production and acutely amplifies the secretory response by increase in mitochondrial export of metabolites. We aimed to narrow down the uniform final reaction steps mediating fuel-induced acute amplification of insulin secretion. MATERIAL/METHODS Insulin secretion and metabolic parameters were measured in isolated mouse islets exposed to the sulfonylurea glipizide in high concentration (closing all ATP-sensitive K(+) channels) during the entire experiment. Fuel-induced effects were examined after treating the islets for one hour with medium devoid of fuels. This experimental design prevented acute amplification, but only when glucose was the sole fuel. RESULTS Strong amplification of insulin secretion by α-ketoisocaproate or glucose combined with α-ketoisovalerate (supplying mitochondrial oxaloacetate) was abolished within 14min after transition to medium devoid of fuels. After transition from medium containing glucose plus α-ketoisovalerate to medium containing solely glucose or α-ketoisovalerate, amplification (strong or weak, respectively) occurred until the end of the experiment. Glucose (alone or combined with α-ketoisovalerate) increased the total acetyl-CoA content as intensely as α-ketoisocaproate. Low concentrations of α-ketoisovalerate or α-ketoisocaproate were sufficient for saturation of acetyl-CoA increase, but caused no or only weak amplification, respectively. No acetyl-CoA increases occurred in the absence of glipizide. CONCLUSIONS Glucose and other fuels regulate acute amplification of insulin secretion by controlling the supply of acetyl-CoA to the ß-cell cytosol. Cytosolic acetyl-CoA does not amplify by serving as substrate for syntheses of metabolic intermediates, but amplifies by acting as substrate for cytosolic protein acetylation.
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Affiliation(s)
- Uwe Panten
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technical University of Braunschweig, Mendelssohnstrasse 1, D-38106 Braunschweig, Germany.
| | - Eike Früh
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technical University of Braunschweig, Mendelssohnstrasse 1, D-38106 Braunschweig, Germany
| | - Kirstin Reckers
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technical University of Braunschweig, Mendelssohnstrasse 1, D-38106 Braunschweig, Germany
| | - Ingo Rustenbeck
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technical University of Braunschweig, Mendelssohnstrasse 1, D-38106 Braunschweig, Germany
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Metformin inhibits Branched Chain Amino Acid (BCAA) derived ketoacidosis and promotes metabolic homeostasis in MSUD. Sci Rep 2016; 6:28775. [PMID: 27373929 PMCID: PMC4931503 DOI: 10.1038/srep28775] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 06/08/2016] [Indexed: 12/12/2022] Open
Abstract
Maple Syrup Urine Disease (MSUD) is an inherited disorder caused by the dysfunction in the branched chain keto-acid dehydrogenase (BCKDH) enzyme. This leads to buildup of branched-chain keto-acids (BCKA) and branched-chain amino acids (BCAA) in body fluids (e.g. keto-isocaproic acid from the BCAA leucine), leading to numerous clinical features including a less understood skeletal muscle dysfunction in patients. KIC is an inhibitor of mitochondrial function at disease relevant concentrations. A murine model of intermediate MSUD (iMSUD) shows significant skeletal muscle dysfunction as by judged decreased muscle fiber diameter. MSUD is an orphan disease with a need for novel drug interventions. Here using a 96-well plate (liquid chromatography- mass spectrometry (LC-MS) based drug-screening platform we show that Metformin, a widely used anti-diabetic drug, reduces levels of KIC in patient-derived fibroblasts by 20–50%. This Metformin-mediated effect was conserved in vivo; Metformin-treatment significantly reduced levels of KIC in the muscle (by 69%) and serum (by 56%) isolated from iMSUD mice, and restored levels of mitochondrial metabolites (e.g. AMP and other TCA). The drug also decreased the expression of mitochondrial branched chain amino transferase (BCAT) which produces KIC in skeletal muscle. This suggests that Metformin can restore skeletal muscle homeostasis in MSUD by decreasing mitochondrial KIC production.
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Yoon MS. The Emerging Role of Branched-Chain Amino Acids in Insulin Resistance and Metabolism. Nutrients 2016; 8:nu8070405. [PMID: 27376324 PMCID: PMC4963881 DOI: 10.3390/nu8070405] [Citation(s) in RCA: 265] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/01/2016] [Accepted: 06/27/2016] [Indexed: 12/12/2022] Open
Abstract
Insulin is required for maintenance of glucose homeostasis. Despite the importance of insulin sensitivity to metabolic health, the mechanisms that induce insulin resistance remain unclear. Branched-chain amino acids (BCAAs) belong to the essential amino acids, which are both direct and indirect nutrient signals. Even though BCAAs have been reported to improve metabolic health, an increased BCAA plasma level is associated with a high risk of metabolic disorder and future insulin resistance, or type 2 diabetes mellitus (T2DM). The activation of mammalian target of rapamycin complex 1 (mTORC1) by BCAAs has been suggested to cause insulin resistance. In addition, defective BCAA oxidative metabolism might occur in obesity, leading to a further accumulation of BCAAs and toxic intermediates. This review provides the current understanding of the mechanism of BCAA-induced mTORC1 activation, as well as the effect of mTOR activation on metabolic health in terms of insulin sensitivity. Furthermore, the effects of impaired BCAA metabolism will be discussed in detail.
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Affiliation(s)
- Mee-Sup Yoon
- Department of Molecular Medicine, School of Medicine, Gachon University, Incheon 406-840, Korea.
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Abstract
Branched-chain amino acids (BCAAs) are important nutrient signals that have direct and indirect effects. Frequently, BCAAs have been reported to mediate antiobesity effects, especially in rodent models. However, circulating levels of BCAAs tend to be increased in individuals with obesity and are associated with worse metabolic health and future insulin resistance or type 2 diabetes mellitus (T2DM). A hypothesized mechanism linking increased levels of BCAAs and T2DM involves leucine-mediated activation of the mammalian target of rapamycin complex 1 (mTORC1), which results in uncoupling of insulin signalling at an early stage. A BCAA dysmetabolism model proposes that the accumulation of mitotoxic metabolites (and not BCAAs per se) promotes β-cell mitochondrial dysfunction, stress signalling and apoptosis associated with T2DM. Alternatively, insulin resistance might promote aminoacidaemia by increasing the protein degradation that insulin normally suppresses, and/or by eliciting an impairment of efficient BCAA oxidative metabolism in some tissues. Whether and how impaired BCAA metabolism might occur in obesity is discussed in this Review. Research on the role of individual and model-dependent differences in BCAA metabolism is needed, as several genes (BCKDHA, PPM1K, IVD and KLF15) have been designated as candidate genes for obesity and/or T2DM in humans, and distinct phenotypes of tissue-specific branched chain ketoacid dehydrogenase complex activity have been detected in animal models of obesity and T2DM.
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Affiliation(s)
- Christopher J Lynch
- Cellular and Molecular Physiology Department, The Pennsylvania State University, 500 University Drive, MC-H166, Hershey, PA 17033, USA
| | - Sean H Adams
- Arkansas Children's Nutrition Center, and Department of Pediatrics, University of Arkansas for Medical Sciences, 15 Children's Way, Little Rock, AR 72202, USA
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Panten U, Willenborg M, Schumacher K, Hamada A, Ghaly H, Rustenbeck I. Acute metabolic amplification of insulin secretion in mouse islets is mediated by mitochondrial export of metabolites, but not by mitochondrial energy generation. Metabolism 2013; 62:1375-86. [PMID: 23790612 DOI: 10.1016/j.metabol.2013.05.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 04/22/2013] [Accepted: 05/08/2013] [Indexed: 12/26/2022]
Abstract
OBJECTIVE The β-cell metabolism of glucose and of some other fuels (e.g. α-ketoisocaproate) generates signals triggering and acutely amplifying insulin secretion. As the pathway coupling metabolism with amplification is largely unknown, we aimed to narrow down the putative amplifying signals. MATERIALS/METHODS An experimental design was used which previously prevented glucose-induced, but not α-ketoisocaproate-induced insulin secretion. Isolated mouse islets were pretreated for one hour with medium devoid of fuels and containing the sulfonylurea glipizide in high concentration which closed all ATP-sensitive K(+) channels. This concentration was also applied during the subsequent examination of fuel-induced effects. In perifused or incubated islets, insulin secretion and metabolic parameters were measured. RESULTS The pretreatment decreased the islet ATP/ADP ratio. Whereas glucose and α-ketoisovalerate were ineffective or weakly effective, respectively, when tested separately, their combination strongly enhanced the insulin secretion. Compared with glucose, the strong amplifier α-ketoisocaproate caused less increase in NAD(P)H-fluorescence and less mitochondrial hyperpolarization. Compared with α-ketoisovalerate, α-ketoisocaproate caused greater increase in NAD(P)H-fluorescence and greater mitochondrial hyperpolarization. Neither α-ketoacid anion enhanced the islet ATP/ADP ratio during onset of the insulin secretion. α-Ketoisocaproate induced a higher pyruvate content than glucose, slowly elevated the citrate content which was not changed by glucose and generated a much higher acetoacetate content than other fuels. α-Ketoisovalerate alone or in combination with glucose did not increase the citrate content. CONCLUSIONS In β-cells, mitochondrial energy generation does not mediate acute metabolic amplification, but mitochondrial production of acetyl-CoA and supplemental acetoacetate supplies cytosolic metabolites which induce the generation of specific amplifying signals.
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Affiliation(s)
- Uwe Panten
- Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technical University of Braunschweig, Mendelssohnstrasse 1, D-38106 Braunschweig, Germany.
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Ribeiro CA, Sgaravatti AM, Rosa RB, Schuck PF, Grando V, Schmidt AL, Ferreira GC, Perry MLS, Dutra-Filho CS, Wajner M. Inhibition of brain energy metabolism by the branched-chain amino acids accumulating in maple syrup urine disease. Neurochem Res 2007; 33:114-24. [PMID: 17680360 DOI: 10.1007/s11064-007-9423-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Accepted: 06/19/2007] [Indexed: 12/13/2022]
Abstract
In the present work we investigated the in vitro effect of the branched-chain amino acids (BCAA) accumulating in maple syrup urine disease (MSUD) on some parameters of energy metabolism in cerebral cortex of rats. 14CO2 production from [1-14C]acetate, [1-5-14C]citrate and [U-14C]glucose, as well as glucose uptake by the brain were evaluated by incubating cortical prisms from 30-day-old rats in the absence (controls) or presence of leucine (Leu), valine (Val) or isoleucine (Ile). All amino acids significantly reduced 14CO2 production by around 20-55%, in contrast to glucose utilization, which was significantly increased by up to 90%. Furthermore, Leu significantly inhibited the activity of the respiratory chain complex IV, whereas Val and Ile markedly inhibited complexes II-III, III and IV by up to 40%. We also observed that trolox (alpha-tocopherol) and creatine totally prevented the inhibitory effects provoked by the BCAA on the respiratory chain complex activities, suggesting that free radicals were involved in these effects. The results indicate that the major metabolites accumulating in MSUD disturb brain aerobic metabolism by compromising the citric acid cycle and the electron flow through the respiratory chain. We presume that these findings may be of relevance to the understanding of the pathophysiology of the neurological dysfunction of MSUD patients.
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Affiliation(s)
- César A Ribeiro
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, CEP 90035-003, Brazil
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Abstract
Despite its high prevalence and severe complications, the aetiology of the primary defects leading to Type 2 diabetes mellitus remain unknown. In addition to polygenic predisposition, environmental factors including dietary behaviour are increasingly recognized as being of crucial importance for the development of this disease. This strongly supports the concept that nutrient excess leading to increased availability of substrates adversely influences whole-body metabolic regulation and plays a major role in the development of type 2 diabetes. We have shown previously that a short-term increase in free fatty acid availability impairs glucose metabolism in liver and skeletal muscle. Despite the widespread interest in protein-rich diets, the effects of plasma amino acid elevation on human glucose metabolism have not yet been studied in detail. This editorial summarizes recent advances in the identification of mechanisms responsible for amino acid-dependent modulation of glucose metabolism in liver and skeletal muscle in vivo.
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Affiliation(s)
- Helene Nørrelund
- Medical Department M (Endocrinology and Diabetes), Aarhus University Hospital, Aarhus Sygehus, Norrebrogade 44, DK-8000 Aarhus C, Denmark.
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de Castro Vasques V, de Boer MA, Diligenti F, Brinco F, Mallmann F, Mello CF, Wajner M. Intrahippocampal administration of the alpha-keto acids accumulating in maple syrup urine disease provokes learning deficits in rats. Pharmacol Biochem Behav 2004; 77:183-90. [PMID: 14724056 DOI: 10.1016/j.pbb.2003.10.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Learning disability is a common feature of patients affected by maple syrup urine disease (MSUD). However, the pathomechanisms underlying learning deficit in this disorder are poorly known. In the present study, we investigated the effect of acute administration of the alpha-keto acids accumulating in MSUD into the hippocampus on the behavior of rats in the open field and in the inhibitory avoidance tasks. Adult male Wistar rats received intrahippocampal injections of alpha-ketoisocaproic acid (KIC, 8 micromol), alpha-ketoisovaleric acid (KIV, 5 micromol), alpha-keto-beta-methylvaleric acid (KMV, 5 micromol), or NaCl (8 micromol) (controls) immediately after or 10 min before training. Testing session was performed 24 h later. Posttraining administration of the keto acids had no effect on learning in the open-field task. In contrast, pretraining administration of KIV and KMV impaired habituation in the open field. Similarly, pretraining administration of KIC, KIV, and KMV affected rat performance in the inhibitory avoidance task, suggesting disruption of acquisition. The results indicate that the alpha-keto acids accumulating in MSUD induce learning deficits in aversive and nonaversive tasks. We therefore suggest that these findings may be related to the psychomotor delay/mental retardation observed in MSUD, and may indicate the contribution of increased brain concentrations of these organic acids to the pathophysiology of the neurological dysfunction of MSUD patients.
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Affiliation(s)
- Vilson de Castro Vasques
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, RS, Porto Alegre, Brazil
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18
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Sgaravatti AM, Rosa RB, Schuck PF, Ribeiro CAJ, Wannmacher CMD, Wyse ATS, Dutra-Filho CS, Wajner M. Inhibition of brain energy metabolism by the alpha-keto acids accumulating in maple syrup urine disease. Biochim Biophys Acta Mol Basis Dis 2004; 1639:232-8. [PMID: 14636955 DOI: 10.1016/j.bbadis.2003.09.010] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Neurological dysfunction is a common finding in patients with maple syrup urine disease (MSUD). However, the mechanisms underlying the neuropathology of brain damage in this disorder are poorly known. In the present study, we investigated the effect of the in vitro effect of the branched chain alpha-keto acids (BCKA) accumulating in MSUD on some parameters of energy metabolism in cerebral cortex of rats. [14CO(2)] production from [14C] acetate, glucose uptake and lactate release from glucose were evaluated by incubating cortical prisms from 30-day-old rats in Krebs-Ringer bicarbonate buffer, pH 7.4, in the absence (controls) or presence of 1-5 mM of alpha-ketoisocaproic acid (KIC), alpha-keto-beta-methylvaleric acid (KMV) or alpha-ketoisovaleric acid (KIV). All keto acids significantly reduced 14CO(2) production by around 40%, in contrast to lactate release and glucose utilization, which were significantly increased by the metabolites by around 42% in cortical prisms. Furthermore, the activity of the respiratory chain complex I-III was significantly inhibited by 60%, whereas the other activities of the electron transport chain, namely complexes II, II-III, III and IV, as well as succinate dehydrogenase were not affected by the keto acids. The results indicate that the major metabolites accumulating in MSUD compromise brain energy metabolism by blocking the respiratory chain. We presume that these findings may be of relevance to the understanding of the pathophysiology of the neurological dysfunction of MSUD patients.
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Affiliation(s)
- Angela M Sgaravatti
- Departamento de Bioqui;mica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, Porto Alegre, RS, Brazil
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19
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Krebs M, Krssak M, Bernroider E, Anderwald C, Brehm A, Meyerspeer M, Nowotny P, Roth E, Waldhäusl W, Roden M. Mechanism of amino acid-induced skeletal muscle insulin resistance in humans. Diabetes 2002; 51:599-605. [PMID: 11872656 DOI: 10.2337/diabetes.51.3.599] [Citation(s) in RCA: 291] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Plasma concentrations of amino acids are frequently elevated in insulin-resistant states, and a protein-enriched diet can impair glucose metabolism. This study examined effects of short-term plasma amino acid (AA) elevation on whole-body glucose disposal and cellular insulin action in skeletal muscle. Seven healthy men were studied for 5.5 h during euglycemic (5.5 mmol/l), hyperinsulinemic (430 pmol/l), fasting glucagon (65 ng/l), and growth hormone (0.4 microg/l) somatostatin clamp tests in the presence of low (approximately 1.6 mmol/l) and increased (approximately 4.6 mmol/l) plasma AA concentrations. Glucose turnover was measured with D-[6,6-(2)H(2)]glucose. Intramuscular concentrations of glycogen and glucose-6-phosphate (G6P) were monitored using (13)C and (31)P nuclear magnetic resonance spectroscopy, respectively. A approximately 2.1-fold elevation of plasma AAs reduced whole-body glucose disposal by 25% (P < 0.01). Rates of muscle glycogen synthesis decreased by 64% (180--315 min, 24 plus minus 3; control, 67 plus minus 10 micromol center dot l(-1) center dot min(-1); P < 0.01), which was accompanied by a reduction in G6P starting at 130 min (DeltaG6P(260--300 min), 18 plus minus 19; control, 103 plus minus 33 micromol/l; P < 0.05). In conclusion, plasma amino acid elevation induces skeletal muscle insulin resistance in humans by inhibition of glucose transport/phosphorylation, resulting in marked reduction of glycogen synthesis.
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Affiliation(s)
- Michael Krebs
- Division of Endocrinology and Metabolism, Department of Internal Medicine III, University of Vienna Medical School, Vienna, Austria
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Jouvet P, Rustin P, Taylor DL, Pocock JM, Felderhoff-Mueser U, Mazarakis ND, Sarraf C, Joashi U, Kozma M, Greenwood K, Edwards AD, Mehmet H. Branched chain amino acids induce apoptosis in neural cells without mitochondrial membrane depolarization or cytochrome c release: implications for neurological impairment associated with maple syrup urine disease. Mol Biol Cell 2000; 11:1919-32. [PMID: 10793161 PMCID: PMC14893 DOI: 10.1091/mbc.11.5.1919] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by a deficiency in branched chain alpha-keto acid dehydrogenase that can result in neurodegenerative sequelae in human infants. In the present study, increased concentrations of MSUD metabolites, in particular alpha-keto isocaproic acid, specifically induced apoptosis in glial and neuronal cells in culture. Apoptosis was associated with a reduction in cell respiration but without impairment of respiratory chain function, without early changes in mitochondrial membrane potential and without cytochrome c release into the cytosol. Significantly, alpha-keto isocaproic acid also triggered neuronal apoptosis in vivo after intracerebral injection into the developing rat brain. These findings suggest that MSUD neurodegeneration may result, at least in part, from an accumulation of branched chain amino acids and their alpha-keto acid derivatives that trigger apoptosis through a cytochrome c-independent pathway.
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Affiliation(s)
- P Jouvet
- Weston Laboratory, Division of Paediatrics, Obstetrics, and Gynaecology, Imperial College of Science, Technology, and Medicine, Hammersmith Hospital, London W12 0NN, United Kingdom
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Martín-Requero A, Ciprés G, Rivas T, Ayuso MS, Parrilla R. Reciprocal changes in gluconeogenesis and ureagenesis induced by fatty acid oxidation. Metabolism 1993; 42:1573-82. [PMID: 8246772 DOI: 10.1016/0026-0495(93)90153-f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Fatty acids produced a stimulation of gluconeogenesis and either inhibition or no effect on ureagenesis in livers perfused with gluconeogenic substrates and having NH4Cl plus ornithine as the nitrogen source. This finding indicates that stimulation of flux through pyruvate carboxylase is not sufficient to enhance urea production from ammonia. The metabolic action of fatty acids showed the following characteristics: (1) it was concentration-dependent, showing saturation-type kinetics similar to those described for fatty acid oxidation; (2) the stimulatory action on gluconeogenesis was constant and independent of NH4Cl concentration, whereas the inhibition of ureagenesis was variable and dependent on NH4Cl concentration and the degree of reduction of the gluconeogenic substrate; and (3) fatty acids produced apparent reciprocal changes in the state of reduction of the cytosolic and mitochondrial NAD systems. Fatty acid oxidation exerted its effect mainly, if not exclusively, by preventing the gluconeogenic substrate-induced stimulation of ureagenesis. Fatty acids also inhibited ureagenesis without stimulating gluconeogenesis (lactate < 1 mmol/L), ruling out a limiting energy availability as the cause of the inhibition. One or both of the following two mechanisms seem to account for the fatty acid-induced inhibition of ureagenesis from NH4Cl. First, a decreased uptake of ornithine, and second, decreased flux through pyruvate dehydrogenase and probably other NAD(P)-linked mitochondrial dehydrogenases. The correlation found between the ability of fatty acids to inhibit ureagenesis and the state of activation of pyruvate dehydrogenase supports the latter point.
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Affiliation(s)
- A Martín-Requero
- Endocrine Physiology Unit, Centro de Investigaciones Biológicas, Madrid, Spain
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23
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Martín-Requero A, Ciprés G, González-Manchón C, Ayuso MS, Parrilla R. Interrelationships between ureogenesis and gluconeogenesis in perfused rat liver. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1158:166-74. [PMID: 8399317 DOI: 10.1016/0304-4165(93)90010-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Stimulation of ureogenesis by ornithine and/or NH4Cl inhibited gluconeogenesis from lactate but not from equimolar concentrations of pyruvate in perfused rat liver. Neither a shortage of energy nor a decrease in alpha-ketoglutarate availability seems to be responsible for this inhibition. With lactate as substrate the extracellular concentration of pyruvate attained was approximately equal to 0.15 mM that assuming reflects its cytosolic concentration it would be limiting for its mitochondrial transport. Stimulation of ureogenesis from NH4Cl enhances flux through pyruvate dehydrogenase. Furthermore, activation of pyruvate dehydrogenase by dichloroacetate led to stimulation of ureogenesis and inhibition of glucose production. Conversely, inhibition of pyruvate dehydrogenase flux by fatty acid enhanced glucose production and inhibited ureogenesis. Thus, ornithine and/or NH4Cl seem to inhibit lactate to glucose flux by shifting the mitochondrial partitioning of pyruvate from carboxylation towards decarboxylation with the result of a decreased oxaloacetate formation. Gluconeogenic substrates enhanced the hepatic uptake of ornithine. However, no correlation seems to exist between the uptake of ornithine, ornithine-induced stimulation of ureogenesis and total rates of urea production. Ornithine produced a concentration-dependent acidification of the hepatic outflow perfusate, suggesting that it may be transported in exchange for H+.
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Affiliation(s)
- A Martín-Requero
- Endocrine Physiology Unit, Centro de Investigaciones Biológicas, C.S.I.C. Madrid, Spain
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Stace PB, Fatania HR, Jackson A, Kerbey AL, Randle PJ. Cyclic AMP and free fatty acids in the longer-term regulation of pyruvate dehydrogenase kinase in rat soleus muscle. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1135:201-6. [PMID: 1319745 DOI: 10.1016/0167-4889(92)90137-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Starvation increased pyruvate dehydrogenase (PDH) kinase activity in extracts of freshly excised rat soleus 2.2-fold (from 0.6 min-1 in fed rats to 1.31 min-1 in 48-h-starved rats). In fed rats, activities were unchanged following 24 h of culture in medium 199, but increased 2.1-fold on 24 h of culture with 50 microM dibutyryl cAMP plus 1 mM n-octanoate and 1.6-1.7-fold with either agent alone. Approx. 70% of the increase in PDH kinase induced by starvation was lost following 24 h of culture in medium 199; the loss was prevented by 50 microM dibutyryl cAMP plus 1 mM n-octanoate. cAMP concentrations in fresh soleus muscle were 1 nmol/g (fed rats) and 1.6 nmol/g (starved rats). After 20-60 min of culture the fed-starved difference disappeared and [cAMP] fell to 0.4 nmol/g. Calcitonin-gene-related peptide (CGRP) increased cAMP 3-fold; the increase was maintained throughout 24 h of culture, but was readily reversed at 30 min or 24 h of culture by 60-min incubation with CGRP-free medium. Starvation of the rat (48 h) had no effect on the sensitivity of soleus towards the [cAMP]-increasing effect of CGRP. It is concluded that culture may reverse effects of starvation on PDH kinase activity by lowering cAMP and by removal from the in vivo effects of circulating free fatty acids; and that starvation and CGRP had no detectable long-term effects on the cAMP system in soleus muscle.
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Affiliation(s)
- P B Stace
- Nuffield Department of Clinical Biochemistry, University of Oxford, John Radcliffe Hospital, UK
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Abstract
Pivalate (trimethylacetic acid) administration in humans or rat has been reported to cause metabolic changes and increased urinary carnitine excretion secondary to pivaloylcarnitine generation. As pivaloylcarnitine formation is dependent on intracellular activation of pivalate, the effects of pivalate on cellular coenzyme A and acyl-CoA contents and oxidative metabolism were defined using isolated rat hepatocytes. During incubations with pivalate (1.0 mM), hepatocyte coenzyme A content fell to less than 0.05 nmol/10(6) cells (vs 0.97 nmol/10(6) cells in the absence of pivalate) as pivaloyl-CoA accumulated. Pivalate (5 mM) inhibited 14CO2 generation from 10 mM [1-14C]pyruvate by 34%, but had no effect on 0.8 mM [1-14C]palmitate oxidation. Pivaloyl-CoA was a substrate for hepatocyte carnitine acyltransferase activity, but supported acylcarnitine formation at rates only 10-20% of those observed with equimolar acetyl-CoA or isovaleryl-CoA as substrates. Thus, hepatocytes activate pivalate to pivaloyl-CoA, which can then be used as a substrate for pivaloylcarnitine formation. The sequestration of hepatocyte coenzyme A as pivaloyl-CoA is associated with inhibition of pyruvate oxidation. As with other organic carboxylic acids, activation of pivalate to the coenzyme A thioester is an important aspect in the biochemical toxicology of the compound.
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Affiliation(s)
- L J Ruff
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4981
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Krahenbuhl S, Brass EP. Inhibition of hepatic propionyl-CoA synthetase activity by organic acids. Reversal of propionate inhibition of pyruvate metabolism. Biochem Pharmacol 1991; 41:1015-23. [PMID: 2009071 DOI: 10.1016/0006-2952(91)90209-n] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Intracellular accumulation of propionyl-CoA is associated with impairment of important hepatic metabolic pathways. Since propionate absorbed from the intestine can be converted to propionyl-CoA in the liver, inhibition of propionyl-CoA synthesis from propionate and CoA may provide a strategy for decreasing toxicity from plasma propionate. Therefore, inhibition of propionyl-CoA formation by several organic acids was investigated. In isolated, solubilized mitochondria, octanoate, butyrate, salicylate and p-nitrobenzoate inhibited propionyl-CoA synthesis. Octanoate was the most potent inhibitor of propionyl-CoA synthetase activity and had a Ki of 58 microM. In isolated hepatocytes, octanoate inhibited propionate oxidation in a concentration-dependent manner. Consistent with previous studies, propionate (1.0 mM) inhibited the rates of 14CO2 formation from [1-14C]pyruvate (10 mM) to 55% of the control values in the hepatocyte system. Octanoate (0.8 mM) had no effect on [1-14C]pyruvate oxidation under control conditions, but increased 14CO2 formation from pyruvate to 88% of the control values in the presence of 1.0 mM propionate. Reversal of propionate inhibition of pyruvate oxidation by octanoate was associated with a 44% decrease in hepatocyte propionyl-CoA content. In contrast, while pyruvate oxidation rates were decreased to 53% of control rates in the presence of 10 mM propionylcarnitine, octanoate stimulated pyruvate oxidation under these conditions only to 67% of control levels. In conclusion, mitochondrial propionyl-CoA synthetase activity and hepatocyte propionyl-CoA accumulation can be inhibited by octanoate with consequent decreased propionate oxidation and toxicity in intact hepatocytes. The reversal by octanoate of propionate's inhibition of cellular metabolism may be useful in reducing tissue toxicity from circulating propionate.
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Affiliation(s)
- S Krahenbuhl
- Department of Medicine, Case Western Reserve University, Cleveland, OH 44106
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Kilberg MS, Handlogten ME. Transport of branched-chain amino acids and their corresponding 2-keto acids by mammalian cells. Methods Enzymol 1988; 166:252-60. [PMID: 3071709 DOI: 10.1016/s0076-6879(88)66034-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Lennon DL, Shrago E, Madden M, Nagle F, Hanson P, Zimmerman S. Carnitine status, plasma lipid profiles, and exercise capacity of dialysis patients: effects of a submaximal exercise program. Metabolism 1986; 35:728-35. [PMID: 3736413 DOI: 10.1016/0026-0495(86)90240-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Carnitine status, blood lipid profiles, and exercise capacity were evaluated in a combined group of hemodialysis (N = 4) and continuous ambulatory peritoneal dialysis (N = 6) patients before and after an 8-week submaximal exercise program. Maximal aerobic capacity (VO2max) was only 18.5 +/- 5.9 (mean +/- SD) mL O2/kg/min, well below the expected 30 to 35 mL O2/kg/min for age-matched sedentary controls. Plasma short-chain acylated carnitine levels, which were two to three times normal values, were reduced after the exercise program, but the long-chain acylcarnitines were significantly reduced during acute exercise. Muscle biopsies of the vastus lateralis were performed at rest in five patients prior to and after the 8-week exercise program. Total carnitine in skeletal muscle was 3.09 (.076 SD) mumol/g ww, with only 11.3% acylated prior to the exercise program, which was much lower than the 4.25 +/- 1.27 mumol/g ww, with 28.5% acylated in a group of healthy athletic subjects (N = 28). Muscle free carnitine concentrations decreased significantly following the 8-week training period, with only a slight reduction in total carnitine. The percent of acylated carnitine was therefore significantly increased (P less than 0.05) from 11.3% to 25.2% after the experimental period. Pretraining carnitine palmitoyl transferase activity at rest was 0.57 +/- 0.28 nmol palmitoyl carnitine formed/5 min/mg mitochondrial protein, which was not changed by exercise training v 1.80 +/- 0.51 nmol/5 min/mg protein in 28 healthy normals (P less than 0.001). Free fatty acid concentrations were reduced significantly during acute exercise as a result of the exercise training program whereas other plasma lipids were not altered. (ABSTRACT TRUNCATED AT 250 WORDS)
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Robertson JG, Barron LL, Olson MS. Effects of alpha-ketoisovalerate on bovine heart pyruvate dehydrogenase complex and pyruvate dehydrogenase kinase. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(17)42433-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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30
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Wałajtys-Rode EI, Nałecz KA, Sterniczuk A, Wojtczak AB. The elucidation of the effect of ammonium chloride on pyruvate distribution and pyruvate dehydrogenase interconversion in isolated rat hepatocytes. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1984; 16:675-80. [PMID: 6468732 DOI: 10.1016/0020-711x(84)90037-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The distribution of pyruvate between cell compartments measured in isolated hepatocytes in the presence of lactate was in agreement with delta pH across plasma and mitochondrial membranes. In isolated liver mitochondria NH4Cl decreased the transmembrane potential (delta psi) by about 14 mV, whereas no change of delta pH was observed. In the presence of lactate or alanine NH4Cl increased the mitochondrial pyruvate concentration presumably due to the inhibition of the flux through pyruvate carboxylase. In the presence of lactate or alanine changes in the amount of the active form of pyruvate dehydrogenase (PDHa) were correlated with the mitochondrial pyruvate concentration, NH4Cl increased the amount of PDHa by lowering the mitochondrial ATP/ADP and NADH/NAD+ ratios.
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Kilberg MS, Gwynn MB. Plasma membrane transport of 2-ketoisocaproate by rat hepatocytes in primary culture. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)44259-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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32
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Geelen MJ. Mechanisms responsible for the inhibitory effects of benfluorex on hepatic intermediary metabolism. Biochem Pharmacol 1983; 32:1765-72. [PMID: 6870919 DOI: 10.1016/0006-2952(83)90123-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The effects of benfluorex on hepatic intermediary metabolism have been studied using the isolated hepatocyte system. The drug inhibits the synthesis of both glucose and fatty acids by hepatocytes. Evidence is obtained that hepatocytes rapidly split benfluorex into benzoic acid and 1-(3-trifluoromethylphenyl)-2-[N-(2-hydroxyethyl)amino]propane (THEP). Comparison of the effects of the parent compound with the effects of THEP and benzoic acid on gluconeogenesis and on fatty acid synthesis indicates that different metabolites of the drug are responsible for its various actions: THEP inhibits gluconeogenesis, whereas benzoic acid inhibits fatty acid synthesis. The latter pathway appears to be inhibited at two sites: mitochondrial pyruvate uptake is inhibited by benfluorex itself, whereas fatty acid synthase is inhibited by benfluorex-derived benzoic acid.
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Martin-Requero A, Corkey BE, Cerdan S, Walajtys-Rode E, Parrilla RL, Williamson JR. Interactions between alpha-ketoisovalerate metabolism and the pathways of gluconeogenesis and urea synthesis in isolated hepatocytes. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32718-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Jackson RH, Singer TP. Inactivation of the 2-ketoglutarate and pyruvate dehydrogenase complexes of beef heart by branched chain keto acids. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)33067-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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McCune SA, Durant PJ, Flanders LE, Harris RA. Inhibition of hepatic gluconeogenesis and lipogenesis by benzoic acid, p-tert.-butylbenzoic acid, and a structurally related hypolipidemic agent SC-33459. Arch Biochem Biophys 1982; 214:124-33. [PMID: 7081992 DOI: 10.1016/0003-9861(82)90014-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Patel TB, Debuysere MS, Scholz R, Olson MS. The regulation of the pyruvate dehydrogenase complex in the perfused rat liver: a role for the mitochondrial monocarboxylate translocator. Arch Biochem Biophys 1982; 213:573-84. [PMID: 6803675 DOI: 10.1016/0003-9861(82)90586-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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38
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Corkey BE, Brandt M, Williams RJ, Williamson JR. Assay of short-chain acyl coenzyme A intermediates in tissue extracts by high-pressure liquid chromatography. Anal Biochem 1981; 118:30-41. [PMID: 6278980 DOI: 10.1016/0003-2697(81)90152-4] [Citation(s) in RCA: 116] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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39
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Patel TB, DeBuysere MS, Barron LL, Olson MS. Studies on the regulation of the branched chain alpha-keto acid dehydrogenase in the perfused rat liver. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)52500-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Gregersen N. The specific inhibition of the pyruvate dehydrogenase complex from pig kidney by propionyl-CoA and isovaleryl-Co-A. BIOCHEMICAL MEDICINE 1981; 26:20-7. [PMID: 7295301 DOI: 10.1016/0006-2944(81)90026-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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41
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Schwarz HP, Karl IE, Bier DM. The alpha-keto acids of branched-chain amino acids: simplified derivatization for physiological samples and complete separation as quinoxalinols by packed column gas chromatography. Anal Biochem 1980; 108:360-6. [PMID: 7457882 DOI: 10.1016/0003-2697(80)90600-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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