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Cornett K, Puderbaugh A, Back O, Craven R. GAPDH in neuroblastoma: Functions in metabolism and survival. Front Oncol 2022; 12:979683. [PMID: 36267982 PMCID: PMC9577191 DOI: 10.3389/fonc.2022.979683] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 09/20/2022] [Indexed: 11/18/2022] Open
Abstract
Neuroblastoma is a pediatric cancer of neural crest cells. It develops most frequently in nerve cells around the adrenal gland, although other locations are possible. Neuroblastomas rely on glycolysis as a source of energy and metabolites, and the enzymes that catalyze glycolysis are potential therapeutic targets for neuroblastoma. Furthermore, glycolysis provides a protective function against DNA damage, and there is evidence that glycolysis inhibitors may improve outcomes from other cancer treatments. This mini-review will focus on glyceraldehyde 3-phosphate dehydrogenase (GAPDH), one of the central enzymes in glycolysis. GAPDH has a key role in metabolism, catalyzing the sixth step in glycolysis and generating NADH. GAPDH also has a surprisingly diverse number of localizations, including the nucleus, where it performs multiple functions, and the plasma membrane. One membrane-associated function of GAPDH is stimulating glucose uptake, consistent with a role for GAPDH in energy and metabolite production. The plasma membrane localization of GAPDH and its role in glucose uptake have been verified in neuroblastoma. Membrane-associated GAPDH also participates in iron uptake, although this has not been tested in neuroblastoma. Finally, GAPDH activates autophagy through a nuclear complex with Sirtuin. This review will discuss these activities and their potential role in cancer metabolism, treatment and drug resistance.
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Fares HM, Lyu X, Xu X, Dong R, Ding M, Mi S, Wang Y, Li X, Yuan S, Sun L. Autophagy in cancer: The cornerstone during glutamine deprivation. Eur J Pharmacol 2022; 916:174723. [PMID: 34973953 DOI: 10.1016/j.ejphar.2021.174723] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 12/13/2021] [Accepted: 12/20/2021] [Indexed: 12/19/2022]
Abstract
Over the past two decades, researchers have revealed the crucial functions of glutamine in supporting the hyperproliferation state of cancer cells. Glutamine acts on maintaining high energy production, supporting redox status and amino acid homeostasis. Therefore, cancer cells exhibit excessive uptake of the extracellular glutamine, synthesize it in some cases, and recycle intracellular and extracellular proteins to provide an additional source of glutamine to satisfy the increasing glutamine demand. On the other hand, autophagy's role is still debated regarding tumor initiation and progression. However, most cancer cells urgently need autophagy to overcome the existential threats during glutamine restriction stress. Downstream to various stress pathways induced during such a condition, autophagy is considered an indispensable cytoprotective tool to maintain cell integrity and survival. However, the overactivation of the autophagy process is related to lethal consequences. This review summarized glutamine pathways to control autophagy and highlighted autophagy's primary activation pathways, and discussed the roles during glutamine deprivation.
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Affiliation(s)
- Hamza M Fares
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China
| | - Xiaodan Lyu
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China
| | - Xiaoting Xu
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China
| | - Renchao Dong
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China
| | - Muyao Ding
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China
| | - Shichao Mi
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China
| | - Yifan Wang
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China
| | - Xue Li
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China
| | - Shengtao Yuan
- Jiangsu Center for Pharmacodynamics Research and Evaluation, China Pharmaceutical University, Nanjing, China
| | - Li Sun
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China.
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Liotta EM, Kimberly WT. Cerebral edema and liver disease: Classic perspectives and contemporary hypotheses on mechanism. Neurosci Lett 2020; 721:134818. [PMID: 32035166 DOI: 10.1016/j.neulet.2020.134818] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 02/07/2023]
Abstract
Liver disease is a growing public health concern. Hepatic encephalopathy, the syndrome of brain dysfunction secondary to liver disease, is a frequent complication of both acute and chronic liver disease and cerebral edema (CE) is a key feature. While altered ammonia metabolism is a key contributor to hepatic encephalopathy and CE in liver disease, there is a growing appreciation that additional mechanisms contribute to CE. In this review we will begin by presenting three classic perspectives that form a foundation for a discussion of CE in liver disease: 1) CE is unique to acute liver failure, 2) CE in liver disease is only cytotoxic, and 3) CE in liver disease is primarily an osmotically mediated consequence of ammonia and glutamine metabolism. We will present each classic perspective along with more recent observations that call in to question that classic perspective. After highlighting these areas of debate, we will explore the leading contemporary mechanisms hypothesized to contribute to CE during liver disease.
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Affiliation(s)
- Eric M Liotta
- Northwestern University-Feinberg School of Medicine, Department of Neurology, United States; Northwestern University-Feinberg School of Medicine, Department of Surgery, Division of Organ Transplantation, United States; Northwestern University Transplant Outcomes Research Collaboration, United States.
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Wong CC, Qian Y, Li X, Xu J, Kang W, Tong JH, To KF, Jin Y, Li W, Chen H, Go MYY, Wu JL, Cheng KW, Ng SSM, Sung JJY, Cai Z, Yu J. SLC25A22 Promotes Proliferation and Survival of Colorectal Cancer Cells With KRAS Mutations and Xenograft Tumor Progression in Mice via Intracellular Synthesis of Aspartate. Gastroenterology 2016; 151:945-960.e6. [PMID: 27451147 DOI: 10.1053/j.gastro.2016.07.011] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 06/14/2016] [Accepted: 07/06/2016] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS Many colorectal cancer (CRC) cells contain mutations in KRAS. Analyses of CRC cells with mutations in APC or CTNNB1 and KRAS identified SLC25A22, which encodes mitochondrial glutamate transporter, as a synthetic lethal gene. We investigated the functions of SLC25A22 in CRC cells with mutations in KRAS. METHODS We measured levels of SLC25A22 messenger RNA and protein in paired tumor and nontumor colon tissues collected from 130 patients in Hong Kong and 17 patients in China and compared protein levels with patient survival times. Expression of SLC25A22 was knocked down in KRAS mutant CRC cell lines (DLD1, HCT116, LOVO, SW480, SW620, and SW1116) and CRC cell lines without mutations in KRAS (CACO-2, COLO205, HT29, and SW48); cells were analyzed for colony formation, proliferation, glutaminolysis and aspartate synthesis, and apoptosis in Matrigel and polymerase chain reaction array analyses. DLD1 and HCT116 cells with SLC25A22 knockdown were grown as xenograft tumors in nude mice; tumor growth and metastasis were measured. SLC25A22 was expressed ectopically in HCT116 cells, which were analyzed in vitro and grown as xenograft tumors in nude mice. RESULTS Levels of SLC25A22 messenger RNA and protein were increased in colorectal tumor tissues compared with matched nontumor colon tissues; increased protein levels were associated with shorter survival times of patients (P = .01). Knockdown of SLC25A22 in KRAS mutant CRC cells reduced their proliferation, migration, and invasion in vitro, and tumor formation and metastasis in mice, compared with cells without SLC25A22 knockdown. Knockdown of SLC25A22 reduced aspartate biosynthesis, leading to apoptosis, decreased cell proliferation in KRAS mutant CRC cells. Incubation of KRAS mutant CRC cells with knockdown of SLC25A22 with aspartate increased proliferation and reduced apoptosis, which required GOT1, indicating that oxaloacetate is required for cell survival. Decreased levels of oxaloacetate in cells with knockdown of SLC25A22 reduced regeneration of oxidized nicotinamide adenine dinucleotide and reduced nicotinamide adenine dinucleotide phosphate. Reduced oxidized nicotinamide adenine dinucleotide inhibited glycolysis and decreased levels of adenosine triphosphate, which inactivated mitogen-activated protein kinase kinase and extracellular signal-regulated kinase signaling via activation of AMP-activated protein kinase. An increased ratio of oxidized nicotinamide adenine dinucleotide phosphate to reduced nicotinamide adenine dinucleotide phosphate induced oxidative stress and glutathione oxidation, which suppressed cell proliferation. Asparagine synthetase mediated synthesis of asparagine from aspartate to promote cell migration. CONCLUSIONS SLC25A22 promotes proliferation and migration of CRC cells with mutations KRAS, and formation and metastasis of CRC xenograft tumors in mice. Patients with colorectal tumors that express increased levels of SLC25A22 have shorter survival times than patients whose tumors have lower levels. SLC25A22 induces intracellular synthesis of aspartate, activation of mitogen-activated protein kinase kinase and extracellular signal-regulated kinase signaling and reduces oxidative stress.
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Affiliation(s)
- Chi Chun Wong
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China.
| | - Yun Qian
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China; Department of Gastroenterology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Zhejiang, China
| | - Xiaona Li
- State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong, China
| | - Jiaying Xu
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China
| | - Wei Kang
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Oncology in South China, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Joanna H Tong
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Oncology in South China, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Ka-Fai To
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Oncology in South China, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Ye Jin
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China
| | - Weilin Li
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China
| | - Huarong Chen
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China
| | - Minnie Y Y Go
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China
| | - Jian-Lin Wu
- State Key Laboratory for Quality Research in Chinese Medicines, Macau University of Science and Technology, Macau, China
| | - Ka Wing Cheng
- College of Engineering, Peking University, Peking, China
| | - Simon S M Ng
- Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China
| | - Joseph J Y Sung
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China
| | - Zongwei Cai
- State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong, China
| | - Jun Yu
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China.
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Chen L, Cui H. Targeting Glutamine Induces Apoptosis: A Cancer Therapy Approach. Int J Mol Sci 2015; 16:22830-55. [PMID: 26402672 PMCID: PMC4613338 DOI: 10.3390/ijms160922830] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 09/11/2015] [Accepted: 09/15/2015] [Indexed: 02/06/2023] Open
Abstract
Glutamine metabolism has been proved to be dysregulated in many cancer cells, and is essential for proliferation of most cancer cells, which makes glutamine an appealing target for cancer therapy. In order to be well used by cells, glutamine must be transported to cells by specific transporters and converted to glutamate by glutaminase. There are currently several drugs that target glutaminase under development or clinical trials. Also, glutamine metabolism restriction has been proved to be effective in inhibiting tumor growth both in vivo and vitro through inducing apoptosis, growth arrest and/or autophagy. Here, we review recent researches about glutamine metabolism in cancer, and cell death induced by targeting glutamine, and their potential roles in cancer therapy.
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Affiliation(s)
- Lian Chen
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, Sichuan Agriculture University, Ya'an 625014, China.
| | - Hengmin Cui
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, Sichuan Agriculture University, Ya'an 625014, China.
- College of Veterinary Medicine, Sichuan Agricultural University, Ya'an 625014, China.
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Kim MH, Kim H. Oncogenes and tumor suppressors regulate glutamine metabolism in cancer cells. J Cancer Prev 2014; 18:221-6. [PMID: 25337549 PMCID: PMC4189465 DOI: 10.15430/jcp.2013.18.3.221] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 09/07/2013] [Accepted: 09/07/2013] [Indexed: 01/21/2023] Open
Abstract
Several hallmarks of cancer cells are their display of metabolic changes and enhanced proliferation. Highly proliferating cells utilize glutamine as a source of nitrogen, and therefore, one of the commonly seen metabolic changes is increased glutaminolysis, or glutamine catabolism. In addition, glutamine is an important anaplerotic source by which cells support the pools of TCA cycle intermediates in Myc-expressing cancer cells. Glutamine is converted to aspartate, which forms oxaloacetate, malate, and pyruvate. These conversions increase the NADPH/NADP(+) ratio and maintain redox balance, which supports proliferation in K-ras-expressing cells. Therefore, glutamine is important for cancer cell proliferation and survival. On the other hand, glutamine stimulates the activation of the tumor suppressor p53, which induces apoptosis and tumor regression. The tumor suppressor SIRT4 inhibits glutamate dehydrogenase, which converts glutamic acid to α-ketoglutarate, an intermediate in the TCA cycle. Overall, the expression levels of oncogenes and tumor suppressors are critical to determine whether glutamine supports or suppresses proliferation and survival of cancer cells.
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Affiliation(s)
- Min Hyun Kim
- Department of Food and Nutrition, Brain Korea 21 PLUS Project, College of Human Ecology, Yonsei University, Seoul, Korea
| | - Hyeyoung Kim
- Department of Food and Nutrition, Brain Korea 21 PLUS Project, College of Human Ecology, Yonsei University, Seoul, Korea
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Glutamate and GABA-Metabolizing Enzymes in Post-mortem Cerebellum in Alzheimer’s Disease: Phosphate-Activated Glutaminase and Glutamic Acid Decarboxylase. THE CEREBELLUM 2014; 13:607-15. [DOI: 10.1007/s12311-014-0573-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Novel treatment with neuroprotective and antiviral properties against a neuroinvasive human respiratory virus. J Virol 2013; 88:1548-63. [PMID: 24227863 DOI: 10.1128/jvi.02972-13] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Human coronaviruses (HCoVs) are recognized respiratory pathogens with neuroinvasive and neurotropic properties in mice and humans. HCoV strain OC43 (HCoV-OC43) can infect and persist in human neural cells and activate neuroinflammatory and neurodegenerative mechanisms, suggesting that it could be involved in neurological disease of unknown etiology in humans. Moreover, we have shown that HCoV-OC43 is neurovirulent in susceptible mice, causing encephalitis, and that a viral mutant with a single point mutation in the viral surface spike (S) protein induces a paralytic disease that involves glutamate excitotoxicity in susceptible mice. Herein, we show that glutamate recycling via the glial transporter 1 protein transporter and glutamine synthetase are central to the dysregulation of glutamate homeostasis and development of motor dysfunctions and paralytic disease in HCoV-OC43-infected mice. Moreover, memantine, an N-methyl-d-aspartate receptor antagonist widely used in the treatment of neurological diseases in humans, improved clinical scores related to paralytic disease and motor disabilities by partially restoring the physiological neurofilament phosphorylation state in virus-infected mice. Interestingly, memantine attenuated mortality rates and body weight loss and reduced HCoV-OC43 replication in the central nervous system in a dose-dependent manner. This novel action of memantine on viral replication strongly suggests that it could be used as an antiviral agent to directly limit viral replication while improving neurological symptoms in various neurological diseases with a viral involvement. Mutations in the surface spike (S) protein of human respiratory coronavirus OC43 appear after persistent infection of human cells of the central nervous system, a possible viral adaptation to this environment. Furthermore, a single amino acid change in the viral S protein modulated virus-induced neuropathology in mice from an encephalitis to a neuropathology characterized by flaccid paralysis, which involves glutamate excitotoxicity. We now show that memantine, a drug that is used for alleviating symptoms associated with neuropathology, such as Alzheimer's disease, can partially restore the physiological state of infected mice by limiting both neurodegeneration and viral replication. This suggests that memantine could be used as an antiviral agent while improving neurological symptoms in various neurological diseases with a viral involvement.
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Rama Rao KV, Norenberg MD. Glutamine in the pathogenesis of hepatic encephalopathy: the trojan horse hypothesis revisited. Neurochem Res 2013; 39:593-8. [PMID: 23277414 DOI: 10.1007/s11064-012-0955-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 12/19/2012] [Indexed: 01/16/2023]
Abstract
Hepatic encephalopathy (HE) is major neuropsychiatric disorder occurring in patients with severe liver disease and ammonia is generally considered to represent the major toxin responsible for this condition. Ammonia in brain is chiefly metabolized ("detoxified") to glutamine in astrocytes due to predominant localization of glutamine synthetase in these cells. While glutamine has long been considered innocuous, a deleterious role more recently has been attributed to this amino acid. This article reviews the mechanisms by which glutamine contributes to the pathogenesis of HE, how glutamine is transported into mitochondria and subsequently hydrolyzed leading to high levels of ammonia, the latter triggering oxidative and nitrative stress, the mitochondrial permeability transition and mitochondrial injury, a sequence of events we have collectively termed as the Trojan horse hypothesis of hepatic encephalopathy.
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Affiliation(s)
- Kakulavarapu V Rama Rao
- Department of Pathology, University of Miami Miller School of Medicine, P.O. BOX 016960, Miami, FL, 33101, USA
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Schousboe A, Bak LK, Waagepetersen HS. Astrocytic Control of Biosynthesis and Turnover of the Neurotransmitters Glutamate and GABA. Front Endocrinol (Lausanne) 2013; 4:102. [PMID: 23966981 PMCID: PMC3744088 DOI: 10.3389/fendo.2013.00102] [Citation(s) in RCA: 193] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/31/2013] [Indexed: 01/20/2023] Open
Abstract
Glutamate and GABA are the quantitatively major neurotransmitters in the brain mediating excitatory and inhibitory signaling, respectively. These amino acids are metabolically interrelated and at the same time they are tightly coupled to the intermediary metabolism including energy homeostasis. Astrocytes play a pivotal role in the maintenance of the neurotransmitter pools of glutamate and GABA since only these cells express pyruvate carboxylase, the enzyme required for de novo synthesis of the two amino acids. Such de novo synthesis is obligatory to compensate for catabolism of glutamate and GABA related to oxidative metabolism when the amino acids are used as energy substrates. This, in turn, is influenced by the extent to which the cycling of the amino acids between neurons and astrocytes may occur. This cycling is brought about by the glutamate/GABA - glutamine cycle the operation of which involves the enzymes glutamine synthetase (GS) and phosphate-activated glutaminase together with the plasma membrane transporters for glutamate, GABA, and glutamine. The distribution of these proteins between neurons and astrocytes determines the efficacy of the cycle and it is of particular importance that GS is exclusively expressed in astrocytes. It should be kept in mind that the operation of the cycle is associated with movement of ammonia nitrogen between the two cell types and different mechanisms which can mediate this have been proposed. This review is intended to delineate the above mentioned processes and to discuss quantitatively their relative importance in the homeostatic mechanisms responsible for the maintenance of optimal conditions for the respective neurotransmission processes to operate.
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Affiliation(s)
- Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- *Correspondence: Arne Schousboe, Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark e-mail:
| | - Lasse K. Bak
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Helle S. Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Cisneros IE, Ghorpade A. HIV-1, methamphetamine and astrocyte glutamate regulation: combined excitotoxic implications for neuro-AIDS. Curr HIV Res 2012; 10:392-406. [PMID: 22591363 PMCID: PMC3580828 DOI: 10.2174/157016212802138832] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 04/18/2012] [Accepted: 04/18/2012] [Indexed: 02/08/2023]
Abstract
Glutamate, the most abundant excitatory transmitter in the brain can lead to neurotoxicity when not properly regulated. Excitotoxicity is a direct result of abnormal regulation of glutamate concentrations in the synapse, and is a common neurotoxic mediator associated with neurodegenerative disorders. It is well accepted that methamphetamine (METH), a potent central nervous stimulant with high abuse potential, and human immunodeficiency virus (HIV)-1 are implicated in the progression of neurocognitive malfunction. Both have been shown to induce common neurodegenerative effects such as astrogliosis, compromised blood brain barrier integrity, and excitotoxicity in the brain. Reduced glutamate uptake from neuronal synapses likely leads to the accumulation of glutamate in the extracellular spaces. Astrocytes express the glutamate transporters responsible for majority of the glutamate uptake from the synapse, as well as for vesicular glutamate release. However, the cellular and molecular mechanisms of astrocyte-mediated excitotoxicity in the context of METH and HIV-1 are undefined. Topics reviewed include dysregulation of the glutamate transporters, specifically excitatory amino acid transporter-2, metabotropic glutamate receptor(s) expression and the release of glutamate by vesicular exocytosis. We also discuss glutamate concentration dysregulation through astrocytic expression of enzymes for glutamate synthesis and metabolism. Lastly, we discuss recent evidence of various astrocyte and neuron crosstalk mechanisms implicated in glutamate regulation. Astrocytes play an essential role in the neuropathologies associated with METH/HIV-1-induced excitotoxicity. We hope to shed light on common cellular and molecular pathways astrocytes share in glutamate regulation during drug abuse and HIV-1 infection.
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Affiliation(s)
| | - Anuja Ghorpade
- University of North Texas Health Science Center, Fort Worth, TX, USA
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Pathogenesis of hepatic encephalopathy and brain edema in acute liver failure: role of glutamine redefined. Neurochem Int 2012; 60:690-6. [PMID: 22382077 DOI: 10.1016/j.neuint.2012.02.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 02/02/2012] [Accepted: 02/04/2012] [Indexed: 11/23/2022]
Abstract
Acute liver failure (ALF) is characterized neuropathologically by cytotoxic brain edema and biochemically by increased brain ammonia and its detoxification product, glutamine. The osmotic actions of increased glutamine synthesis in astrocytes are considered to be causally related to brain edema and its complications (intracranial hypertension, brain herniation) in ALF. However studies using multinuclear (1)H- and (13)C-NMR spectroscopy demonstrate that neither brain glutamine concentrations per se nor brain glutamine synthesis rates correlate with encephalopathy grade or the presence of brain edema in ALF. An alternative mechanism is now proposed whereby the newly synthesized glutamine is trapped within the astrocyte as a consequence of down-regulation of its high affinity glutamine transporter SNAT5 in ALF. Restricted transfer out of the cell rather than increased synthesis within the cell could potentially explain the cell swelling/brain edema in ALF. Moreover, the restricted transfer of glutamine from the astrocyte to the adjacent glutamatergic nerve terminal (where glutamine serves as immediate precursor for the releasable/transmitter pool of glutamate) could result in decreased excitatory transmission and excessive neuroinhibition that is characteristic of encephalopathy in ALF. Paradoxically, in spite of renewed interest in arterial ammonia as a predictor of raised intracranial pressure and brain herniation in ALF, ammonia-lowering agents aimed at reduction of ammonia production in the gut have so far been shown to be of limited value in the prevention of these cerebral consequences. Mild hypothermia, shown to prevent brain edema and intracranial hypertension in both experimental and human ALF, does so independent of effects on brain glutamine synthesis; whether or not hypothermia restores expression levels of SNAT5 in ALF awaits further studies. While inhibitors of brain glutamine synthesis such as methionine sulfoximine, have been proposed for the prevention of brain edema in ALF, potential adverse effects have so far limited their applicability.
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Friday E, Oliver R, Welbourne T, Turturro F. Glutaminolysis and glycolysis regulation by troglitazone in breast cancer cells: Relationship to mitochondrial membrane potential. J Cell Physiol 2011; 226:511-9. [PMID: 20683912 DOI: 10.1002/jcp.22360] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We studied the roles of glycolysis and glutaminolysis following an acute reduction in mitochondrial membrane potential (Ψ(m)) induced by the thiazolidinedione troglitazone (TRO) and compared the responses with CCCP-induced depolarization in breast cancer derived MCF-7 and MDA-MB-231 cells as well as in the MCF-10A normal breast cell line. TRO and CCCP both acutely reduced Ψ(m) but after 24 h TRO-treated cells had restored Ψ(m) associated with both increased glycolysis and glutaminolysis. In contrast, CCCP-treated cells exhibited only a partial restoration of Ψ(m) associated with increased glycolysis but decreased glutaminolysis. TRO-induced glutaminolysis was coupled to increased ammonium (GDH flux) and decreased alanine production (ALT flux) in all three cell lines. Both cancer cell lines exhibited a higher spontaneous GDH/ALT flux than the normal breast cell line associated with a reduced keto-acid pool. TRO's effect on GDH/ALT fluxes and mitochondrial keto-acid pool homeostasis was additive with glucose withdrawal suggesting limited intramitochondrial pyruvate availability. The TRO-induced acceleration in GDH flux supplies substrate for Complex I contributing to the restoration of Ψ(m) as well as Krebs cycle intermediates for biosynthesis. Inhibiting mitochondrial proton ATPase with oligomycin or nullifying the proton gradient with CCCP prevented both the TRO-induced recovery of Ψ(m) and accelerated GDH flux but restored ALT flux consonant with important roles for proton pumping in regulating GDH flux and Ψ(m) recovery. Blocking enhanced GDH flux reduced DNA synthesis consistent with glutaminolysis via GDH playing an important biosynthetic role in tumorigenesis.
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Affiliation(s)
- Ellen Friday
- Department of Medicine, Feist-Weiller Cancer Center, Louisiana State University Health Science Center, Shreveport, Louisiana 71103, USA.
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Brusilow SW, Koehler RC, Traystman RJ, Cooper AJL. Astrocyte glutamine synthetase: importance in hyperammonemic syndromes and potential target for therapy. Neurotherapeutics 2010; 7:452-70. [PMID: 20880508 PMCID: PMC2975543 DOI: 10.1016/j.nurt.2010.05.015] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 05/17/2010] [Accepted: 05/19/2010] [Indexed: 12/21/2022] Open
Abstract
Many theories have been advanced to explain the encephalopathy associated with chronic liver disease and with the less common acute form. A major factor contributing to hepatic encephalopathy is hyperammonemia resulting from portacaval shunting and/or liver damage. However, an increasing number of causes of hyperammonemic encephalopathy have been discovered that present with the same clinical and laboratory features found in acute liver failure, but without liver failure. Here, we critically review the physiology, pathology, and biochemistry of ammonia (i.e., NH3 plus NH4+) and show how these elements interact to constitute a syndrome that clinicians refer to as hyperammonemic encephalopathy (i.e., acute liver failure, fulminant hepatic failure, chronic liver disease). Included will be a brief history of the status of ammonia and the centrality of the astrocyte in brain nitrogen metabolism. Ammonia is normally detoxified in the liver and extrahepatic tissues by conversion to urea and glutamine, respectively. In the brain, glutamine synthesis is largely confined to astrocytes, and it is generally accepted that in hyperammonemia excess glutamine compromises astrocyte morphology and function. Mechanisms postulated to account for this toxicity will be examined with emphasis on the osmotic effects of excess glutamine (the osmotic gliopathy theory). Because hyperammonemia causes osmotic stress and encephalopathy in patients with normal or abnormal liver function alike, the term "hyperammonemic encephalopathy" can be broadly applied to encephalopathy resulting from liver disease and from various other diseases that produce hyperammonemia. Finally, the possibility that a brain glutamine synthetase inhibitor may be of therapeutic benefit, especially in the acute form of liver disease, is discussed.
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Affiliation(s)
- Saul W. Brusilow
- grid.21107.350000000121719311Department of Pediatrics, The Johns Hopkins University School of Medicine, 21287 Baltimore, MD
| | - Raymond C. Koehler
- grid.21107.350000000121719311Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, 21287 Baltimore, MD
| | - Richard J. Traystman
- Office of the Vice Chancellor for Research, Department of Pharmacology, University of Colorado Denver, 80045 Aurora, CO
| | - Arthur J. L. Cooper
- grid.260917.b000000010728151XDepartment of Biochemistry and Molecular Biology, New York Medical College, 10595 Valhalla, NY
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Masola B, Ngubane NP. The activity of phosphate-dependent glutaminase from the rat small intestine is modulated by ADP and is dependent on integrity of mitochondria. Arch Biochem Biophys 2010; 504:197-203. [PMID: 20831857 DOI: 10.1016/j.abb.2010.09.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 08/29/2010] [Accepted: 09/01/2010] [Indexed: 11/20/2022]
Abstract
The effect of adenine nucleotides and phosphate on rat small intestine phosphate-dependent glutaminase (PDG) activity was investigated in intact mitochondria. Disruption of the integrity of mitochondria by sonication or freeze-thawing resulted in loss of enzyme activity. ADP was the strongest adenine nucleotide activator of the enzyme giving a V(max) that was over 5-fold of that for AMP or ATP. The sigmoid activation curve of PDG by ADP became hyperbolic in presence ATP. ADP also lowered the K(m) for glutamine and increased V(max) and these effects were further enhanced by the presence of ATP. Activation of PDG by phosphate and ADP was not completely additive suggesting some antagonism between the activators. There was no clear relationship between changing ATP/ADP ratios and PDG activity in presence of a constant concentration of phosphate. However, ratios of approximately 1:4 and 4:1 gave the highest and lowest activities, respectively. The pH dependence of PDG activity was affected by phosphate concentration and results suggest that the divalent ion is the activating species.
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Affiliation(s)
- B Masola
- Department of Biochemistry, University of KwaZulu-Natal, Durban, South Africa.
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16
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Phosphate-activated glutaminase (GLS2), a p53-inducible regulator of glutamine metabolism and reactive oxygen species. Proc Natl Acad Sci U S A 2010; 107:7461-6. [PMID: 20351271 DOI: 10.1073/pnas.1002459107] [Citation(s) in RCA: 475] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We identified a p53 target gene, phosphate-activated mitochondrial glutaminase (GLS2), a key enzyme in conversion of glutamine to glutamate, and thereby a regulator of glutathione (GSH) synthesis and energy production. GLS2 expression is induced in response to DNA damage or oxidative stress in a p53-dependent manner, and p53 associates with the GLS2 promoter. Elevated GLS2 facilitates glutamine metabolism and lowers intracellular reactive oxygen species (ROS) levels, resulting in an overall decrease in DNA oxidation as determined by measurement of 8-OH-dG content in both normal and stressed cells. Further, siRNA down-regulation of either GLS2 or p53 compromises the GSH-dependent antioxidant system and increases intracellular ROS levels. High ROS levels following GLS2 knockdown also coincide with stimulation of p53-induced cell death. We propose that GLS2 control of intracellular ROS levels and the apoptotic response facilitates the ability of p53 to protect cells from accumulation of genomic damage and allows cells to survive after mild and repairable genotoxic stress. Indeed, overexpression of GLS2 reduces the growth of tumor cells and colony formation. Further, compared with normal tissue, GLS2 expression is reduced in liver tumors. Thus, our results provide evidence for a unique metabolic role for p53, linking glutamine metabolism, energy, and ROS homeostasis, which may contribute to p53 tumor suppressor function.
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Roberg BA, Torgner IA, Kvamme E. Kinetics of a novel isoform of phosphate activated glutaminase (PAG) in SH-SY5Y neuroblastoma cells. Neurochem Res 2009; 35:875-80. [PMID: 19894115 DOI: 10.1007/s11064-009-0077-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2009] [Indexed: 11/25/2022]
Abstract
We have recently found that the neuroblastoma cell line SH-SY5Y expresses a novel form of phosphate activated glutaminase (PAG) which deamidates glutamine to glutamate and ammonia at high rates. Glutamate production is enhanced during the exponential phase of growth, and decreases when cell proliferation stops. Neuroblastoma PAG exists in a soluble and membrane associated form, and both the phosphate and the glutamine kinetics, as well as the effects of ammonia and glutamate are different from those of the known forms of PAG. Neuroblastoma PAG is mitochondrial, and our immunoblotting analyses of isolated mitochondria shows that our C-terminal antibody reacts with a protein of 65 kDa, while our N-terminal antibody primarily labels a protein of 58 kDa and to a minor degree one of 65 kDa. This strongly suggests that neuroblastoma cells mainly contain an active isoform of PAG lacking the C-terminal end, probably the GAC form.
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Affiliation(s)
- B A Roberg
- Department of Biochemistry, Neurochemical Section, Institute of Basic Medical Sciences, University of Oslo, PO Box 1112, Blindern, 0317, Oslo, Norway.
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