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Moedas MF, Simões RJM, Silva MFB. Mitochondrial targets in hyperammonemia: Addressing urea cycle function to improve drug therapies. Biochem Pharmacol 2024; 222:116034. [PMID: 38307136 DOI: 10.1016/j.bcp.2024.116034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 12/27/2023] [Accepted: 01/25/2024] [Indexed: 02/04/2024]
Abstract
The urea cycle (UC) is a critically important metabolic process for the disposal of nitrogen (ammonia) produced by amino acids catabolism. The impairment of this liver-specific pathway induced either by primary genetic defects or by secondary causes, namely those associated with hepatic disease or drug administration, may result in serious clinical consequences. Urea cycle disorders (UCD) and certain organic acidurias are the major groups of inherited rare diseases manifested with hyperammonemia (HA) with UC dysregulation. Importantly, several commonly prescribed drugs, including antiepileptics in monotherapy or polytherapy from carbamazepine to valproic acid or specific antineoplastic agents such as asparaginase or 5-fluorouracil may be associated with HA by mechanisms not fully elucidated. HA, disclosing an imbalance between ammoniagenesis and ammonia disposal via the UC, can evolve to encephalopathy which may lead to significant morbidity and central nervous system damage. This review will focus on biochemical mechanisms related with HA emphasizing some poorly understood perspectives behind the disruption of the UC and mitochondrial energy metabolism, namely: i) changes in acetyl-CoA or NAD+ levels in subcellular compartments; ii) post-translational modifications of key UC-related enzymes, namely acetylation, potentially affecting their catalytic activity; iii) the mitochondrial sirtuins-mediated role in ureagenesis. Moreover, the main UCD associated with HA will be summarized to highlight the relevance of investigating possible genetic mutations to account for unexpected HA during certain pharmacological therapies. The ammonia-induced effects should be avoided or overcome as part of safer therapeutic strategies to protect patients under treatment with drugs that may be potentially associated with HA.
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Affiliation(s)
- Marco F Moedas
- Research Institute for Medicines-iMed.ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal; Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden; Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Ricardo J M Simões
- Research Institute for Medicines-iMed.ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal
| | - Margarida F B Silva
- Research Institute for Medicines-iMed.ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal.
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2
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Pan C, Mao S, Xiong Z, Chen Z, Xu N. Glutamate dehydrogenase: Potential therapeutic targets for neurodegenerative disease. Eur J Pharmacol 2023; 950:175733. [PMID: 37116563 DOI: 10.1016/j.ejphar.2023.175733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 03/31/2023] [Accepted: 04/17/2023] [Indexed: 04/30/2023]
Abstract
Glutamate dehydrogenase (GDH) is a key enzyme in mammalian glutamate metabolism. It is located at the intersection of multiple metabolic pathways and participates in a variety of cellular activities. GDH activity is strictly regulated by a variety of allosteric compounds. Here, we review the unique distribution and expressions of GDH in the brain nervous system. GDH plays an essential role in the glutamate-glutamine-GABA cycle between astrocytes and neurons. The dysfunction of GDH may induce the occurrence of many neurodegenerative diseases, such as Parkinson's disease, epilepsy, Alzheimer's disease, schizophrenia, and frontotemporal dementia. GDH activators and gene therapy have been found to protect neurons and improve motor disorders in neurodegenerative diseases caused by glutamate metabolism disorders. To date, no medicine has been discovered that specifically targets neurodegenerative diseases, although several potential medicines are used clinically. Targeting GDH to treat neurodegenerative diseases is expected to provide new insights and treatment strategies.
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Affiliation(s)
- Chuqiao Pan
- College of Pharmaceutical Science, Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Huzhou, 313200, Zhejiang, People's Republic of China
| | - Shijie Mao
- College of Pharmaceutical Science, Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Huzhou, 313200, Zhejiang, People's Republic of China
| | - Zeping Xiong
- Department of Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, Huzhou, 313200, Zhejiang, People's Republic of China
| | - Zhao Chen
- College of Pharmaceutical Science, Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Huzhou, 313200, Zhejiang, People's Republic of China
| | - Ning Xu
- College of Pharmaceutical Science, Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Huzhou, 313200, Zhejiang, People's Republic of China.
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3
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Arnold PK, Finley LW. Regulation and function of the mammalian tricarboxylic acid cycle. J Biol Chem 2022; 299:102838. [PMID: 36581208 PMCID: PMC9871338 DOI: 10.1016/j.jbc.2022.102838] [Citation(s) in RCA: 53] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/15/2022] [Accepted: 12/20/2022] [Indexed: 12/27/2022] Open
Abstract
The tricarboxylic acid (TCA) cycle, otherwise known as the Krebs cycle, is a central metabolic pathway that performs the essential function of oxidizing nutrients to support cellular bioenergetics. More recently, it has become evident that TCA cycle behavior is dynamic, and products of the TCA cycle can be co-opted in cancer and other pathologic states. In this review, we revisit the TCA cycle, including its potential origins and the history of its discovery. We provide a detailed accounting of the requirements for sustained TCA cycle function and the critical regulatory nodes that can stimulate or constrain TCA cycle activity. We also discuss recent advances in our understanding of the flexibility of TCA cycle wiring and the increasingly appreciated heterogeneity in TCA cycle activity exhibited by mammalian cells. Deeper insight into how the TCA cycle can be differentially regulated and, consequently, configured in different contexts will shed light on how this pathway is primed to meet the requirements of distinct mammalian cell states.
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Affiliation(s)
- Paige K. Arnold
- Cell Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York, USA,Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Lydia W.S. Finley
- Cell Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York, USA,For correspondence: Lydia W. S. Finley
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Fukui K, Takahashi T, Matsunari H, Uchikura A, Watanabe M, Nagashima H, Ishihara N, Kakuma T, Watanabe Y, Yamashita Y, Yoshino M. Moving towards a novel therapeutic strategy for hyperammonemia that targets glutamine metabolism. J Inherit Metab Dis 2022; 45:1059-1069. [PMID: 35866457 DOI: 10.1002/jimd.12540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 07/15/2022] [Accepted: 07/19/2022] [Indexed: 11/11/2022]
Abstract
Patients with urea cycle disorders intermittently develop episodes of decompensation with hyperammonemia. Although such an episode is often associated with starvation and catabolism, its molecular basis is not fully understood. First, we attempted to elucidate the mechanism of such starvation-associated hyperammonemia. Using a mouse embryonic fibroblast (MEF) culture system, we found that glucose starvation increases ammonia production, and that this increase is associated with enhanced glutaminolysis. These results led us to focus on α-ketoglutarate (AKG), a glutamate dehydrogenase inhibitor, and a major anaplerotic metabolite. Hence, we sought to determine the effect of dimethyl α-ketoglutarate (DKG), a cell-permeable AKG analog, on MEFs and found that DKG mitigates ammonia production primarily by reducing flux through glutamate dehydrogenase. We also verified that DKG reduces ammonia in an NH4 Cl-challenged hyperammonemia mouse model and observed that DKG administration reduces plasma ammonia concentration to 22.8% of the mean value for control mice that received only NH4 Cl. In addition, we detected increases in ornithine concentration and in the ratio of ornithine to arginine following DKG treatment. We subsequently administered DKG intravenously to a newborn pig with hyperammonemia due to ornithine transcarbamylase deficiency and found that blood ammonia concentration declined significantly over time. We determined that this effect is associated with facilitated reductive amination and glutamine synthesis. Our present data indicate that energy starvation triggers hyperammonemia through enhanced glutaminolysis and that DKG reduces ammonia accumulation via pleiotropic mechanisms both in vitro and in vivo. Thus, cell-permeable forms of AKG are feasible candidates for a novel hyperammonemia treatment.
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Affiliation(s)
- Kaori Fukui
- Department of Pediatrics and Child Health, Kurume University School of Medicine, Kurume, Japan
| | - Tomoyuki Takahashi
- Department of Pediatrics and Child Health, Kurume University School of Medicine, Kurume, Japan
- Division of Gene Therapy and Regenerative Medicine, Cognitive and Molecular Research Institute of Brain Diseases, Kurume University, Kurume, Japan
| | - Hitomi Matsunari
- Meiji University International Institute for Bio-Resource Research, Kawasaki, Japan
- Laboratory of Medical Engineering, Meiji University, Kawasaki, Japan
| | - Ayuko Uchikura
- Laboratory of Medical Engineering, Meiji University, Kawasaki, Japan
| | - Masahito Watanabe
- Meiji University International Institute for Bio-Resource Research, Kawasaki, Japan
| | - Hiroshi Nagashima
- Meiji University International Institute for Bio-Resource Research, Kawasaki, Japan
- Laboratory of Medical Engineering, Meiji University, Kawasaki, Japan
| | - Naotada Ishihara
- Department of Protein Biochemistry, Institute of Life Science, Kurume University, Kurume, Japan
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | | | - Yoriko Watanabe
- Department of Pediatrics and Child Health, Kurume University School of Medicine, Kurume, Japan
- Research Institute of Medical Mass Spectrometry, Kurume University School of Medicine, Kurume, Japan
| | - Yushiro Yamashita
- Department of Pediatrics and Child Health, Kurume University School of Medicine, Kurume, Japan
| | - Makoto Yoshino
- Division of Gene Therapy and Regenerative Medicine, Cognitive and Molecular Research Institute of Brain Diseases, Kurume University, Kurume, Japan
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Sirtuin 4 Inhibits Prostate Cancer Progression and Metastasis by Modulating p21 Nuclear Translocation and Glutamate Dehydrogenase 1 ADP-Ribosylation. JOURNAL OF ONCOLOGY 2022; 2022:5498743. [PMID: 35847357 PMCID: PMC9283077 DOI: 10.1155/2022/5498743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 05/14/2022] [Accepted: 05/31/2022] [Indexed: 11/18/2022]
Abstract
Protein posttranslational modification regulates several biological mechanisms, including tumor progression. In this study, we show that the mitochondrial Sirtuin 4 (SIRT4), which has ADP-ribosylation activity, plays a role in prostate cancer (PCa) progression. Firstly, SIRT4 expression was verified in PCa tissues and cell lines by quantitative real-time PCR (qRT-PCR) and western blotting. Subsequently, we established stable PC-3 and 22rv1 cells that overexpressed SIRT4 and knocked down SIRT4, respectively. The functions of SIRT4 in PCa were explored through various phenotype experiments. The mechanism underlying the functions of SIRT4 was investigated through western blotting, immunoprecipitation, immunofluorescence, and nuclear and cytoplasmic extraction assays. We revealed that SIRT4 inhibited cell progression both in vivo and in vitro. Mechanistically, on the one hand, SIRT4 promoted the ADP-ribosylation of glutamate dehydrogenase 1 to inhibit the glutamine metabolism pathways. On the other hand, SIRT4 inhibited the phosphorylation of AKT, thereby affecting p21 phosphorylation and its cellular localization for cell cycle arrest. In conclusion, our study indicates that SIRT4 is directly associated with PCa progression and could be a novel target for PCa therapy.
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Yang Y, He P, Hou Y, Liu Z, Zhang X, Li N. Osmundacetone modulates mitochondrial metabolism in non-small cell lung cancer cells by hijacking the glutamine/glutamate/α-KG metabolic axis. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2022; 100:154075. [PMID: 35413646 DOI: 10.1016/j.phymed.2022.154075] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 02/05/2022] [Accepted: 03/25/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Osmundacetone (OSC) is a bioactive phenolic compound isolated from Phellinus igniarius and that was shown to exert cytotoxic effects on cancer cells in our previous work. The antiproliferative impact of OSC on non-small cell lung cancer (NSCLC) and the underlying mechanisms, however, have not been studied. PURPOSE This study aimed to explore the antiproliferative effect of OSC on NSCLC cells and the mechanisms involved. METHODS Cell viability, colony formation and cell cycle distribution were measured following exposure to OSC in vitro. The anticancer activity of OSC was also examined using a xenograft growth assay in vivo. Furthermore, serum metabolomics analysis by GC-MS was done to detect alterations in the metabolic profile. Next, expression of GLS1 and GLUD1, the key enzymes in glutamine metabolism, was evaluated using RT-PCR and western blot. α-KG and NADH metabolites were assessed by ELISA. Mitochondrial functions and morphology were evaluated using the JC-1 probe and transmission electron microscopy, respectively. The ATP production rate in mitochondria of cells with OSC treatment was determined using a Seahorse XFe24 Analyzer. RESULTS OSC selectively reduced the proliferation of A549 and H460 cells. OSC triggered G2/M cell cycle arrest and decreased the cell clone formation. A mouse xenograft model revealed that OSC inhibited tumor growth in vivo. Findings of serum metabolomics analyses indicated that the anticancer function of OSC was related to disorders of glutamine metabolism. Such a speculation was further verified by the expression level of GLUD1, which was downregulated by OSC treatment. Concentrations of the related metabolites α-KG and NADH were reduced in response to OSC treatment. Moreover, OSC led to disorganization of the mitochondrial ultrastructure and a decrease in mitochondrial membrane potential. OSC also decreased ATP production via oxidative phosphorylation (OXPHOS) but did not affect glycolysis in NSCLC cells. CONCLUSION The key role of OSC in mitochondrial energy metabolism in NSCLC cells is to suppress tumor development and cell proliferation downregulating GLUD1 to inhibit the glutamine/glutamate/α-KG metabolic axis and OXPHOS. It indicats that OSC might be a potential natural agent for personalized medicine and an anticancer metabolic modulator in NSCLC chemotherapy.
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Affiliation(s)
- Yue Yang
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei 230032, China
| | - Pingya He
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei 230032, China
| | - Yuhao Hou
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei 230032, China
| | - Zhicheng Liu
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei 230032, China
| | - Xiaoping Zhang
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei 230032, China
| | - Ning Li
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Medical University, Hefei 230032, China.
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New Insight in Hyperinsulinism/Hyperammonemia Syndrome by Magnetic Resonance Imaging and Spectroscopy. Brain Sci 2022; 12:brainsci12030389. [PMID: 35326344 PMCID: PMC8946637 DOI: 10.3390/brainsci12030389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/21/2022] [Accepted: 03/07/2022] [Indexed: 11/16/2022] Open
Abstract
Hyperinsulinism/hyperammonemia syndrome (HI/HA) is an autosomal dominant disorder caused by monoallelic activating mutations in the glutamate dehydrogenase 1 (GLUD1) gene. While hyperinsulinism may be explained by a reduction in the allosteric inhibition of GLUD1, the pathogenesis of HA in HI/HA remains uncertain; interestingly, HA in the HI/HA syndrome is not associated with acute hyperammonemic intoxication events. We obtained a brain magnetic resonance (MR) in a woman with HI/HA syndrome with chronic asymptomatic HA. On MR spectroscopy, choline and myoinositol were decreased as in other HA disorders. In contrast, distinct from other HA disorders, combined glutamate and glutamine levels were normal (not increased). This observation suggests that brain biochemistry in HI/HA may differ from that of other HA disorders. In HI/HA, ammonia overproduction may come to the expense of glutamate levels, and this seems to prevent the condensation of ammonia with glutamate to produce glutamine that is typical of the other HA disorders. The absence of combined glutamate and glutamine elevation might be correlated to the absence of acute cerebral ammonia toxicity.
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Bian Y, Hou W, Chen X, Fang J, Xu N, Ruan BH. Glutamate Dehydrogenase as a Promising Target for Hyperinsulinism Hyperammonemia Syndrome Therapy. Curr Med Chem 2021; 29:2652-2672. [PMID: 34525914 DOI: 10.2174/0929867328666210825105342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 11/22/2022]
Abstract
Hyperinsulinism-hyperammonemia syndrome (HHS) is a rare disease characterized by recurrent hypoglycemia and persistent elevation of plasma ammonia, and it can lead to severe epilepsy and permanent brain damage. It has been demonstrated that functional mutations of glutamate dehydrogenase (GDH), an enzyme in the mitochondrial matrix, are responsible for the HHS. Thus, GDH has become a promising target for the small molecule therapeutic intervention of HHS. Several medicinal chemistry studies are currently aimed at GDH, however, to date, none of the compounds reported has been entered clinical trials. This perspective summarizes the progress in the discovery and development of GDH inhibitors, including the pathogenesis of HHS, potential binding sites, screening methods, and research models. Future therapeutic perspectives are offered to provide a reference for discovering potent GDH modulators and encourage additional research that will provide more comprehensive guidance for drug development.
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Affiliation(s)
- Yunfei Bian
- College of Pharmaceutical Science, Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hantgzhou 310014. China
| | - Wei Hou
- College of Pharmaceutical Science, Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hantgzhou 310014. China
| | - Xinrou Chen
- College of Pharmaceutical Science, Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hantgzhou 310014. China
| | - Jinzhang Fang
- College of Pharmaceutical Science, Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hantgzhou 310014. China
| | - Ning Xu
- College of Pharmaceutical Science, Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hantgzhou 310014. China
| | - Benfang Helen Ruan
- College of Pharmaceutical Science, Institute of Drug Development & Chemical Biology, Zhejiang University of Technology, Hantgzhou 310014. China
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Moreno-Sánchez R, Marín-Hernández Á, Gallardo-Pérez JC, Pacheco-Velázquez SC, Robledo-Cadena DX, Padilla-Flores JA, Saavedra E, Rodríguez-Enríquez S. Physiological Role of Glutamate Dehydrogenase in Cancer Cells. Front Oncol 2020; 10:429. [PMID: 32328457 PMCID: PMC7160333 DOI: 10.3389/fonc.2020.00429] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 03/10/2020] [Indexed: 12/29/2022] Open
Abstract
NH 4 + increased growth rates and final densities of several human metastatic cancer cells. To assess whether glutamate dehydrogenase (GDH) in cancer cells may catalyze the reverse reaction of NH 4 + fixation, its covalent regulation and kinetic parameters were determined under near-physiological conditions. Increased total protein and phosphorylation were attained in NH 4 + -supplemented metastatic cells, but total cell GDH activity was unchanged. Higher V max values for the GDH reverse reaction vs. forward reaction in both isolated hepatoma (HepM) and liver mitochondria [rat liver mitochondria (RLM)] favored an NH 4 + -fixing role. GDH sigmoidal kinetics with NH 4 + , ADP, and leucine fitted to Hill equation showed n H values of 2 to 3. However, the K 0.5 values for NH 4 + were over 20 mM, questioning the physiological relevance of the GDH reverse reaction, because intracellular NH 4 + in tumors is 1 to 5 mM. In contrast, data fitting to the Monod-Wyman-Changeux (MWC) model revealed lower K m values for NH 4 + , of 6 to 12 mM. In silico analysis made with MWC equation, and using physiological concentrations of substrates and modulators, predicted GDH N-fixing activity in cancer cells. Therefore, together with its thermodynamic feasibility, GDH may reach rates for its reverse, NH 4 + -fixing reaction that are compatible with an anabolic role for supporting growth of cancer cells.
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Affiliation(s)
- Rafael Moreno-Sánchez
- Departamento de Bioquímica, Instituto Nacional de Cardiología, Ciudad de México, Mexico
| | | | - Juan C Gallardo-Pérez
- Departamento de Bioquímica, Instituto Nacional de Cardiología, Ciudad de México, Mexico
| | | | | | | | - Emma Saavedra
- Departamento de Bioquímica, Instituto Nacional de Cardiología, Ciudad de México, Mexico
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10
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Discovery and development of small molecule modulators targeting glutamine metabolism. Eur J Med Chem 2019; 163:215-242. [DOI: 10.1016/j.ejmech.2018.11.066] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 12/22/2022]
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Hou Y, Wu G. L-Glutamate nutrition and metabolism in swine. Amino Acids 2018; 50:1497-1510. [PMID: 30116978 DOI: 10.1007/s00726-018-2634-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/03/2018] [Indexed: 10/28/2022]
Abstract
L-Glutamate (Glu) has traditionally not been considered as a nutrient needed in diets for humans and other animals (including swine) due to the unsubstantiated assumption that animals can synthesize sufficient amounts of Glu to meet their needs. The lack of knowledge about Glu nutrition has contributed to suboptimal efficiency of global livestock production. Over the past 25 years, there has been growing interest in Glu metabolism in the pig, which is an agriculturally important species and also a useful model for studying human biology. Because of analytical advances in its analysis, Glu is now known to be a highly abundant free amino acid in milk and intracellular fluid, a major constituent of food and tissue proteins, and a key regulator of gene expression, cell signaling, and anti-oxidative reactions. Emerging evidence shows that dietary supplementation with 2% Glu maintains gut health and prevents intestinal dysfunction in weanling piglets, while enhancing their growth performance and survival. In addition, the inclusion of 2% Glu is required for dietary arginine to maximize the growth performance and feed efficiency in growing pigs, whereas dietary supplementation with 2% Glu reduces the loss of skeletal muscle mass in endotoxin-challenged pigs. Furthermore, supplementing 2% Glu to a corn- and soybean-meal-based diet promotes milk production by lactating sows. Thus, an adequate amount of dietary Glu as a quantitatively major nutrient is necessary to support maximum growth, development, and production performance of swine. These results also have important implications for improving the nutrition and health of humans and other animals.
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Affiliation(s)
- Yongqing Hou
- Hubei Key Laboratory of Animal Nutrition and Feed Science, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Wuhan Polytechnic University, Wuhan, 430023, China
| | - Guoyao Wu
- Hubei Key Laboratory of Animal Nutrition and Feed Science, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Wuhan Polytechnic University, Wuhan, 430023, China. .,Department of Animal Science, Texas A&M University, College Station, TX, 77843, USA.
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Mansilla WD, Silva KE, Zhu C, Nyachoti CM, Htoo JK, Cant JP, de Lange CFM. Ammonia-Nitrogen Added to Low-Crude-Protein Diets Deficient in Dispensable Amino Acid-Nitrogen Increases the Net Release of Alanine, Citrulline, and Glutamate Post-Splanchnic Organ Metabolism in Growing Pigs. J Nutr 2018; 148:1081-1087. [PMID: 29878142 DOI: 10.1093/jn/nxy076] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/20/2018] [Indexed: 01/27/2023] Open
Abstract
Background Dietary ammonia is rapidly absorbed but poorly used for urea synthesis in pigs fed low-crude-protein (low-CP) diets deficient in dispensable amino acid (DAA)-nitrogen. Objective We explored the effect of dietary ammonia on net amino acid (AA) balances in portal-drained viscera (PDV) and livers of pigs fed a diet deficient in DAA-nitrogen. Methods Eight barrows with an initial body weight (BW) of 26.5 ± 1.4 kg (mean + SD) were surgically fitted with 4 catheters each (portal, hepatic, and mesenteric veins and carotid artery). The pigs were restricted-fed (2.8 × 191 kcal/kg BW0.60) for 7 d, and every 8 h a diet deficient in DAA-nitrogen supplemented with increasing amounts of ammonia-nitrogen (CP = 7.76%, 9.27%, and 10.77% for the control and low- and high-ammonia diets, respectively). The treatment sequence was based on a 3 × 3 Latin-square design with 3 consecutive periods. On the last day of each period, blood flows in portal and hepatic veins were determined with a continuous infusion of ρ-amino hippuric acid into the mesenteric vein. Consecutive blood samples were taken for AA concentration in blood plasma, and AA balances were calculated for PDV and the liver. Results Cumulative release of citrulline (Cit) and proline (Pro) increased with ammonia supplementation in PDV but decreased for glutamine (Gln) and glycine (Gly) (Gln: -19.32 ± 3.56, -32.50 ± 3.73, and -42.11 ± 3.55 mmol/meal for the control and low- and high-ammonia groups, respectively; P ≤ 0.05). Cumulative release of alanine (Ala), glutamic acid (Glu), and Gln increased with ammonia supplementation across the liver (P ≤ 0.05). When combined, PDV+liver, the cumulative release of Ala, Cit, and Glu increased with ammonia-nitrogen supplementation (P ≤ 0.05). Conclusion Dietary ammonia could be used as a nitrogen supplement to increase the synthesis of Ala, Cit, and Glu across splanchnic organs in pigs fed a diet deficient in DAA-nitrogen.
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Affiliation(s)
- Wilfredo D Mansilla
- Department of Animal Biosciences, University of Guelph, Guelph, Ontario, Canada
| | - Kayla E Silva
- Department of Animal Biosciences, University of Guelph, Guelph, Ontario, Canada
| | - Cuilan Zhu
- Department of Animal Biosciences, University of Guelph, Guelph, Ontario, Canada
| | - Charles M Nyachoti
- Department of Animal Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - John K Htoo
- Evonik Nutrition and Care GmbH, Hanau-Wolfgang, Germany
| | - John P Cant
- Department of Animal Biosciences, University of Guelph, Guelph, Ontario, Canada
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Spinelli JB, Haigis MC. The multifaceted contributions of mitochondria to cellular metabolism. Nat Cell Biol 2018; 20:745-754. [PMID: 29950572 PMCID: PMC6541229 DOI: 10.1038/s41556-018-0124-1] [Citation(s) in RCA: 854] [Impact Index Per Article: 142.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 05/17/2018] [Indexed: 02/07/2023]
Abstract
Although classically appreciated for their role as the powerhouse of the cell, the metabolic functions of mitochondria reach far beyond bioenergetics. In this Review, we discuss how mitochondria catabolize nutrients for energy, generate biosynthetic precursors for macromolecules, compartmentalize metabolites for the maintenance of redox homeostasis and function as hubs for metabolic waste management. We address the importance of these roles in both normal physiology and in disease.
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Affiliation(s)
- Jessica B Spinelli
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
- Ludwig Center, Harvard Medical School, Boston, MA, USA
| | - Marcia C Haigis
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
- Ludwig Center, Harvard Medical School, Boston, MA, USA.
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14
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Wang YQ, Wang HL, Xu J, Tan J, Fu LN, Wang JL, Zou TH, Sun DF, Gao QY, Chen YX, Fang JY. Sirtuin5 contributes to colorectal carcinogenesis by enhancing glutaminolysis in a deglutarylation-dependent manner. Nat Commun 2018; 9:545. [PMID: 29416026 PMCID: PMC5803207 DOI: 10.1038/s41467-018-02951-4] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 01/09/2018] [Indexed: 12/12/2022] Open
Abstract
Reversible post-translational modifications represent a mechanism to control tumor metabolism. Here we show that mitochondrial Sirtuin5 (SIRT5), which mediates lysine desuccinylation, deglutarylation, and demalonylation, plays a role in colorectal cancer (CRC) glutamine metabolic rewiring. Metabolic profiling identifies that deletion of SIRT5 causes a marked decrease in 13C-glutamine incorporation into tricarboxylic-acid (TCA) cycle intermediates and glutamine-derived non-essential amino acids. This reduces the building blocks required for rapid growth. Mechanistically, the direct interaction between SIRT5 and glutamate dehydrogenase 1 (GLUD1) causes deglutarylation and functional activation of GLUD1, a critical regulator of cellular glutaminolysis. Consistently, GLUD1 knockdown diminishes SIRT5-induced proliferation, both in vivo and in vitro. Clinically, overexpression of SIRT5 is significantly correlated with poor prognosis in CRC. Thus, SIRT5 supports the anaplerotic entry of glutamine into the TCA cycle in malignant phenotypes of CRC via activating GLUD1.
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Affiliation(s)
- Yun-Qian Wang
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China
| | - Hao-Lian Wang
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China
| | - Jie Xu
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China
| | - Juan Tan
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China
| | - Lin-Na Fu
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China
| | - Ji-Lin Wang
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China
| | - Tian-Hui Zou
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China
| | - Dan-Feng Sun
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China
| | - Qin-Yan Gao
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China
| | - Ying-Xuan Chen
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China. .,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China. .,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.
| | - Jing-Yuan Fang
- Division of Gastroenterology and Hepatology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China.,State Key Laboratory for Oncogenes and Related Genes, Shanghai Institute of Digestive Disease, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 145 Middle Shandong Road, Shanghai, 200001, China
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15
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Spinelli JB, Yoon H, Ringel AE, Jeanfavre S, Clish CB, Haigis MC. Metabolic recycling of ammonia via glutamate dehydrogenase supports breast cancer biomass. Science 2017; 358:941-946. [PMID: 29025995 PMCID: PMC5748897 DOI: 10.1126/science.aam9305] [Citation(s) in RCA: 270] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 09/29/2017] [Indexed: 12/12/2022]
Abstract
Ammonia is a ubiquitous by-product of cellular metabolism; however, the biological consequences of ammonia production are not fully understood, especially in cancer. We found that ammonia is not merely a toxic waste product but is recycled into central amino acid metabolism to maximize nitrogen utilization. In our experiments, human breast cancer cells primarily assimilated ammonia through reductive amination catalyzed by glutamate dehydrogenase (GDH); secondary reactions enabled other amino acids, such as proline and aspartate, to directly acquire this nitrogen. Metabolic recycling of ammonia accelerated proliferation of breast cancer. In mice, ammonia accumulated in the tumor microenvironment and was used directly to generate amino acids through GDH activity. These data show that ammonia is not only a secreted waste product but also a fundamental nitrogen source that can support tumor biomass.
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Affiliation(s)
- Jessica B Spinelli
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Haejin Yoon
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Alison E Ringel
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Sarah Jeanfavre
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Clary B Clish
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Marcia C Haigis
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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16
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Abstract
The resurgence of research into cancer metabolism has recently broadened interests beyond glucose and the Warburg effect to other nutrients, including glutamine. Because oncogenic alterations of metabolism render cancer cells addicted to nutrients, pathways involved in glycolysis or glutaminolysis could be exploited for therapeutic purposes. In this Review, we provide an updated overview of glutamine metabolism and its involvement in tumorigenesis in vitro and in vivo, and explore the recent potential applications of basic science discoveries in the clinical setting.
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Affiliation(s)
- Brian J. Altman
- Abramson Family Cancer Research Institute, Perelman School of
Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Abramson Cancer Center, Perelman School of Medicine, University of
Pennsylvania, Philadelphia, PA, 19104, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman
School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Zachary E. Stine
- Abramson Family Cancer Research Institute, Perelman School of
Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Abramson Cancer Center, Perelman School of Medicine, University of
Pennsylvania, Philadelphia, PA, 19104, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman
School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Chi V. Dang
- Abramson Family Cancer Research Institute, Perelman School of
Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Abramson Cancer Center, Perelman School of Medicine, University of
Pennsylvania, Philadelphia, PA, 19104, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman
School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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17
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Central Role of Glutamate Metabolism in the Maintenance of Nitrogen Homeostasis in Normal and Hyperammonemic Brain. Biomolecules 2016; 6:biom6020016. [PMID: 27023624 PMCID: PMC4919911 DOI: 10.3390/biom6020016] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 03/10/2016] [Accepted: 03/15/2016] [Indexed: 12/21/2022] Open
Abstract
Glutamate is present in the brain at an average concentration—typically 10–12 mM—far in excess of those of other amino acids. In glutamate-containing vesicles in the brain, the concentration of glutamate may even exceed 100 mM. Yet because glutamate is a major excitatory neurotransmitter, the concentration of this amino acid in the cerebral extracellular fluid must be kept low—typically µM. The remarkable gradient of glutamate in the different cerebral compartments: vesicles > cytosol/mitochondria > extracellular fluid attests to the extraordinary effectiveness of glutamate transporters and the strict control of enzymes of glutamate catabolism and synthesis in well-defined cellular and subcellular compartments in the brain. A major route for glutamate and ammonia removal is via the glutamine synthetase (glutamate ammonia ligase) reaction. Glutamate is also removed by conversion to the inhibitory neurotransmitter γ-aminobutyrate (GABA) via the action of glutamate decarboxylase. On the other hand, cerebral glutamate levels are maintained by the action of glutaminase and by various α-ketoglutarate-linked aminotransferases (especially aspartate aminotransferase and the mitochondrial and cytosolic forms of the branched-chain aminotransferases). Although the glutamate dehydrogenase reaction is freely reversible, owing to rapid removal of ammonia as glutamine amide, the direction of the glutamate dehydrogenase reaction in the brain in vivo is mainly toward glutamate catabolism rather than toward the net synthesis of glutamate, even under hyperammonemia conditions. During hyperammonemia, there is a large increase in cerebral glutamine content, but only small changes in the levels of glutamate and α-ketoglutarate. Thus, the channeling of glutamate toward glutamine during hyperammonemia results in the net synthesis of 5-carbon units. This increase in 5-carbon units is accomplished in part by the ammonia-induced stimulation of the anaplerotic enzyme pyruvate carboxylase. Here, we suggest that glutamate may constitute a buffer or bulwark against changes in cerebral amine and ammonia nitrogen. Although the glutamate transporters are briefly discussed, the major emphasis of the present review is on the enzymology contributing to the maintenance of glutamate levels under normal and hyperammonemic conditions. Emphasis will also be placed on the central role of glutamate in the glutamine-glutamate and glutamine-GABA neurotransmitter cycles between neurons and astrocytes. Finally, we provide a brief and selective discussion of neuropathology associated with altered cerebral glutamate levels.
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18
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Botman D, Tigchelaar W, Van Noorden CJF. Determination of glutamate dehydrogenase activity and its kinetics in mouse tissues using metabolic mapping (quantitative enzyme histochemistry). J Histochem Cytochem 2014; 62:802-12. [PMID: 25124006 PMCID: PMC4230541 DOI: 10.1369/0022155414549071] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Glutamate dehydrogenase (GDH) catalyses the reversible conversion of glutamate into α-ketoglutarate with the concomitant reduction of NAD(P)(+) to NAD(P)H or vice versa. GDH activity is subject to complex allosteric regulation including substrate inhibition. To determine GDH kinetics in situ, we assessed the effects of various glutamate concentrations in combination with either the coenzyme NAD(+) or NADP(+) on GDH activity in mouse liver cryostat sections using metabolic mapping. NAD(+)-dependent GDH V(max) was 2.5-fold higher than NADP(+)-dependent V(max), whereas the K(m) was similar, 1.92 mM versus 1.66 mM, when NAD(+) or NADP(+) was used, respectively. With either coenzyme, V(max) was determined at 10 mM glutamate and substrate inhibition was observed at higher glutamate concentrations with a K(i) of 12.2 and 3.95 for NAD(+) and NADP(+) used as coenzyme, respectively. NAD(+)- and NADP(+)-dependent GDH activities were examined in various mouse tissues. GDH activity was highest in liver and much lower in other tissues. In all tissues, the highest activity was found when NAD(+) was used as a coenzyme. In conclusion, GDH activity in mice is highest in the liver with NAD(+) as a coenzyme and highest GDH activity was determined at a glutamate concentration of 10 mM.
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Affiliation(s)
- Dennis Botman
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands (DB, WT, CJFVN)
| | - Wikky Tigchelaar
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands (DB, WT, CJFVN)
| | - Cornelis J F Van Noorden
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands (DB, WT, CJFVN)
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19
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Schachter D, Buteau J. Glutamate formation via the leucine-to-glutamate pathway of rat pancreas. Am J Physiol Gastrointest Liver Physiol 2014; 306:G938-46. [PMID: 24699330 DOI: 10.1152/ajpgi.00394.2013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The leucine-to-glutamate (Leu→Glu) pathway, which metabolizes the carbon atoms of l-leucine to form l-glutamate, was studied by incubation of rat tissue segments with l-[U-(14)C]leucine and estimation of the [(14)C]glutamate formed. Metabolism of the leucine carbon chain occurs in most rat tissues, but maximal activity of the Leu→Glu pathway for glutamate formation is limited to the thoracic aorta and pancreas. In rat aorta, the Leu→Glu pathway functions to relax the underlying smooth muscle; its functions in the pancreas are unknown. This report characterizes the Leu→Glu pathway of rat pancreas and develops methods to examine its functions. Pancreatic segments effect net formation of glutamate on incubation with l-leucine, l-glutamine, or a mix of 18 other plasma amino acids at their concentrations in normal rat plasma. Glutamate formed from leucine remains mainly in the tissue, whereas that from glutamine enters the medium. The pancreatic Leu→Glu pathway uses the leucine carbons for net glutamate formation; the α-amino group is not used; the stoichiometry is as follows: 1 mol of leucine yields 2 mol of glutamate (2 leucine carbons per glutamate) plus 2 mol of CO2. Comparison of the Leu→Glu pathway in preparations of whole pancreatic segments, isolated acini, and islets of Langerhans localizes it in the acini; relatively high activity is found in cultures of the AR42J cell line and very little in the INS-1 832/13 cell line. Pancreatic tissue glutamate concentration is homeostatically regulated in the range of ∼1-3 μmol/g wet wt. l-Valine and leucine ethyl, benzyl, and tert-butyl esters inhibit the Leu→Glu pathway without decreasing tissue total glutamate.
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Affiliation(s)
- David Schachter
- Department of Physiology and Cellular Biophysics, Columbia University College of Physicians and Surgeons, New York, New York; and
| | - Jean Buteau
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, and University of Alberta, Edmonton, Alberta, Canada
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20
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Intertissue Differences for the Role of Glutamate Dehydrogenase in Metabolism. Neurochem Res 2013; 39:516-26. [DOI: 10.1007/s11064-013-0998-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 01/24/2013] [Accepted: 02/01/2013] [Indexed: 11/26/2022]
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21
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The role of glutamine synthetase and glutamate dehydrogenase in cerebral ammonia homeostasis. Neurochem Res 2012; 37:2439-55. [PMID: 22618691 DOI: 10.1007/s11064-012-0803-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 04/24/2012] [Accepted: 05/07/2012] [Indexed: 02/07/2023]
Abstract
In the brain, glutamine synthetase (GS), which is located predominantly in astrocytes, is largely responsible for the removal of both blood-derived and metabolically generated ammonia. Thus, studies with [(13)N]ammonia have shown that about 25 % of blood-derived ammonia is removed in a single pass through the rat brain and that this ammonia is incorporated primarily into glutamine (amide) in astrocytes. Major pathways for cerebral ammonia generation include the glutaminase reaction and the glutamate dehydrogenase (GDH) reaction. The equilibrium position of the GDH-catalyzed reaction in vitro favors reductive amination of α-ketoglutarate at pH 7.4. Nevertheless, only a small amount of label derived from [(13)N]ammonia in rat brain is incorporated into glutamate and the α-amine of glutamine in vivo. Most likely the cerebral GDH reaction is drawn normally in the direction of glutamate oxidation (ammonia production) by rapid removal of ammonia as glutamine. Linkage of glutamate/α-ketoglutarate-utilizing aminotransferases with the GDH reaction channels excess amino acid nitrogen toward ammonia for glutamine synthesis. At high ammonia levels and/or when GS is inhibited the GDH reaction coupled with glutamate/α-ketoglutarate-linked aminotransferases may, however, promote the flow of ammonia nitrogen toward synthesis of amino acids. Preliminary evidence suggests an important role for the purine nucleotide cycle (PNC) as an additional source of ammonia in neurons (Net reaction: L-Aspartate + GTP + H(2)O → Fumarate + GDP + P(i) + NH(3)) and in the beat cycle of ependyma cilia. The link of the PNC to aminotransferases and GDH/GS and its role in cerebral nitrogen metabolism under both normal and pathological (e.g. hyperammonemic encephalopathy) conditions should be a productive area for future research.
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22
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Glutamate: a truly functional amino acid. Amino Acids 2012; 45:413-8. [DOI: 10.1007/s00726-012-1280-4] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 03/26/2012] [Indexed: 12/30/2022]
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23
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Spanaki C, Plaitakis A. The role of glutamate dehydrogenase in mammalian ammonia metabolism. Neurotox Res 2011; 21:117-27. [PMID: 22038055 DOI: 10.1007/s12640-011-9285-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 10/08/2011] [Accepted: 10/11/2011] [Indexed: 01/17/2023]
Abstract
Glutamate dehydrogenase (GDH) catalyzes the reversible inter-conversion of glutamate to α-ketoglutarate and ammonia. High levels of GDH activity is found in mammalian liver, kidney, brain, and pancreas. In the liver, GDH reaction appears to be close-to-equilibrium, providing the appropriate ratio of ammonia and amino acids for urea synthesis in periportal hepatocytes. In addition, GDH produces glutamate for glutamine synthesis in a small rim of pericentral hepatocytes. Hence, hepatic GDH can be either a source for ammonia or an ammonia scavenger. In the kidney, GDH function produces ammonia from glutamate to control acidosis. In the human, the presence of two differentially regulated isoforms (hGDH1 and hGDH2) suggests a complex role for GDH in ammonia homeostasis. Whereas hGDH1 is sensitive to GTP inhibition, hGDH2 has dissociated its function from GTP control. Furthermore, hGDH2 shows a lower optimal pH than hGDH1. The hGDH2 enzyme is selectively expressed in human astrocytes and Sertoli cells, probably facilitating metabolic recycling processes essential for their supportive role. Here, we report that hGDH2 is also expressed in the epithelial cells lining the convoluted tubules of the renal cortex. As hGDH2 functions more efficiently under acidotic conditions without the operation of the GTP energy switch, its presence in the kidney may increase the efficacy of the organ to maintain acid base equilibrium.
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Affiliation(s)
- Cleanthe Spanaki
- Department of Neurology, Medical School, University of Crete, Voutes, 71003, Heraklion, Crete, Greece.
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24
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Romanov V, Whyard T, Bonala R, Johnson F, Grollman A. Glutamate dehydrogenase requirement for apoptosis induced by aristolochic acid in renal tubular epithelial cells. Apoptosis 2011; 16:1217-28. [DOI: 10.1007/s10495-011-0646-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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25
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Karaca M, Frigerio F, Maechler P. From pancreatic islets to central nervous system, the importance of glutamate dehydrogenase for the control of energy homeostasis. Neurochem Int 2011; 59:510-7. [DOI: 10.1016/j.neuint.2011.03.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 03/21/2011] [Accepted: 03/23/2011] [Indexed: 11/25/2022]
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26
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Nissim I, Horyn O, Nissim I, Daikhin Y, Caldovic L, Barcelona B, Cervera J, Tuchman M, Yudkoff M. Down-regulation of hepatic urea synthesis by oxypurines: xanthine and uric acid inhibit N-acetylglutamate synthase. J Biol Chem 2011; 286:22055-68. [PMID: 21540182 DOI: 10.1074/jbc.m110.209023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously reported that isobutylmethylxanthine (IBMX), a derivative of oxypurine, inhibits citrulline synthesis by an as yet unknown mechanism. Here, we demonstrate that IBMX and other oxypurines containing a 2,6-dione group interfere with the binding of glutamate to the active site of N-acetylglutamate synthetase (NAGS), thereby decreasing synthesis of N-acetylglutamate, the obligatory activator of carbamoyl phosphate synthase-1 (CPS1). The result is reduction of citrulline and urea synthesis. Experiments were performed with (15)N-labeled substrates, purified hepatic CPS1, and recombinant mouse NAGS as well as isolated mitochondria. We also used isolated hepatocytes to examine the action of various oxypurines on ureagenesis and to assess the ameliorating affect of N-carbamylglutamate and/or l-arginine on NAGS inhibition. Among various oxypurines tested, only IBMX, xanthine, or uric acid significantly increased the apparent K(m) for glutamate and decreased velocity of NAGS, with little effect on CPS1. The inhibition of NAGS is time- and dose-dependent and leads to decreased formation of the CPS1-N-acetylglutamate complex and consequent inhibition of citrulline and urea synthesis. However, such inhibition was reversed by supplementation with N-carbamylglutamate. The data demonstrate that xanthine and uric acid, both physiologically occurring oxypurines, inhibit the hepatic synthesis of N-acetylglutamate. An important and novel concept emerging from this study is that xanthine and/or uric acid may have a role in the regulation of ureagenesis and, thus, nitrogen homeostasis in normal and disease states.
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Affiliation(s)
- Itzhak Nissim
- Division of Child Development, Rehabilitation Medicine, and Metabolic Disease, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.
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27
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Stanley CA. Two genetic forms of hyperinsulinemic hypoglycemia caused by dysregulation of glutamate dehydrogenase. Neurochem Int 2010; 59:465-72. [PMID: 21130127 DOI: 10.1016/j.neuint.2010.11.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 11/18/2010] [Accepted: 11/24/2010] [Indexed: 02/02/2023]
Abstract
Glutamate dehydrogenase (GDH) has recently been shown to be involved in two genetic disorders of hyperinsulinemic hypoglycemia in children. These include the hyperinsulinism/hyperammonemia syndrome caused by dominant activating mutations of GLUD1 which interfere with inhibitory regulation by GTP and hyperinsulinism due to recessive deficiency of short-chain 3-hydroxy-acyl-CoA dehydrogenase (SCHAD, encoded by HADH1). The clinical manifestations of the abnormalities in pancreatic ß-cell insulin regulation include fasting hypoglycemia, as well as protein-sensitive hypoglycemia. The latter is due to abnormally increased sensitivity of affected children to stimulation of insulin secretion by the amino acid, leucine. In patients with GDH activating mutations, mild hyperammonemia occurs in both the basal and protein-fed state, possibly due to increased renal ammoniagenesis. Some patients with GDH activating mutations appear to be at unusual risk of developmental delay and generalized epilepsy, perhaps reflecting consequences of increased GDH activity in the brain. Studies of these two disorders have been carried out in mouse models to define the mechanisms of insulin dysregulation. In SCHAD deficiency, the activation of GDH is due to loss of a direct inhibitory protein-protein interaction between SCHAD and GDH. These two novel human disorders demonstrate the important role of GDH in insulin regulation and illustrate unexpectedly important reasons for the unusually complex allosteric regulation of GDH.
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Affiliation(s)
- Charles A Stanley
- University of Pennsylvania School of Medicine, Endocrinology Division, The Children's Hospital of Philadelphia, Philadelphia, PA 19026, United States.
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28
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Cooper AJL. 13N as a tracer for studying glutamate metabolism. Neurochem Int 2010; 59:456-64. [PMID: 21108979 DOI: 10.1016/j.neuint.2010.11.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Revised: 11/15/2010] [Accepted: 11/16/2010] [Indexed: 11/26/2022]
Abstract
This mini-review summarizes studies my associates and I carried out that are relevant to the topic of the present volume [i.e. glutamate dehydrogenase (GDH)] using radioactive (13)N (t(1/2) 9.96 min) as a biological tracer. These studies revealed the previously unrecognized rapidity with which nitrogen is exchanged among certain metabolites in vivo. For example, our work demonstrated that (a) the t(1/2) for conversion of portal vein ammonia to urea in the rat liver is ∼10-11s, despite the need for five enzyme-catalyzed steps and two mitochondrial transport steps, (b) the residence time for ammonia in the blood of anesthetized rats is ≤7-8s, (c) the t(1/2) for incorporation of blood-borne ammonia into glutamine in the normal rat brain is <3s, and (d) equilibration between glutamate and aspartate nitrogen in rat liver is extremely rapid (seconds), a reflection of the fact that the components of the hepatic aspartate aminotransferase reaction are in thermodynamic equilibrium. Our work emphasizes the importance of the GDH reaction in rat liver as a conduit for dissimilating or assimilating ammonia as needed. In contrast, our work shows that the GDH reaction in rat brain appears to operate mostly in the direction of ammonia production (dissimilation). The importance of the GDH reaction as an endogenous source of ammonia in the brain and the relation of GDH to the brain glutamine cycle is discussed. Finally, our work integrates with the increasing use of positron emission tomography (PET) and nuclear magnetic resonance (NMR) to study brain ammonia uptake and brain glutamine, respectively, in normal individuals and in patients with liver disease or other diseases associated with hyperammonemia.
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Affiliation(s)
- Arthur J L Cooper
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, United States.
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Li C, Chen P, Palladino A, Narayan S, Russell LK, Sayed S, Xiong G, Chen J, Stokes D, Butt YM, Jones PM, Collins HW, Cohen NA, Cohen AS, Nissim I, Smith TJ, Strauss AW, Matschinsky FM, Bennett MJ, Stanley CA. Mechanism of hyperinsulinism in short-chain 3-hydroxyacyl-CoA dehydrogenase deficiency involves activation of glutamate dehydrogenase. J Biol Chem 2010; 285:31806-18. [PMID: 20670938 DOI: 10.1074/jbc.m110.123638] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanism of insulin dysregulation in children with hyperinsulinism associated with inactivating mutations of short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD) was examined in mice with a knock-out of the hadh gene (hadh(-/-)). The hadh(-/-) mice had reduced levels of plasma glucose and elevated plasma insulin levels, similar to children with SCHAD deficiency. hadh(-/-) mice were hypersensitive to oral amino acid with decrease of glucose level and elevation of insulin. Hypersensitivity to oral amino acid in hadh(-/-) mice can be explained by abnormal insulin responses to a physiological mixture of amino acids and increased sensitivity to leucine stimulation in isolated perifused islets. Measurement of cytosolic calcium showed normal basal levels and abnormal responses to amino acids in hadh(-/-) islets. Leucine, glutamine, and alanine are responsible for amino acid hypersensitivity in islets. hadh(-/-) islets have lower intracellular glutamate and aspartate levels, and this decrease can be prevented by high glucose. hadh(-/-) islets also have increased [U-(14)C]glutamine oxidation. In contrast, hadh(-/-) mice have similar glucose tolerance and insulin sensitivity compared with controls. Perifused hadh(-/-) islets showed no differences from controls in response to glucose-stimulated insulin secretion, even with addition of either a medium-chain fatty acid (octanoate) or a long-chain fatty acid (palmitate). Pull-down experiments with SCHAD, anti-SCHAD, or anti-GDH antibodies showed protein-protein interactions between SCHAD and GDH. GDH enzyme kinetics of hadh(-/-) islets showed an increase in GDH affinity for its substrate, α-ketoglutarate. These studies indicate that SCHAD deficiency causes hyperinsulinism by activation of GDH via loss of inhibitory regulation of GDH by SCHAD.
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Affiliation(s)
- Changhong Li
- Division of Endocrinology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
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