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Antunes BC, Mateus T, Morais VA. In the Brain, It Is Not All about Sugar. NEUROSCI 2024; 5:209-221. [PMID: 39483499 PMCID: PMC11493208 DOI: 10.3390/neurosci5020016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 06/04/2024] [Accepted: 06/11/2024] [Indexed: 11/03/2024] Open
Abstract
The maintenance of energetic homeostasis relies on a tight balance between glycolysis and mitochondrial oxidative phosphorylation. The case of the brain is a peculiar one, as although entailing a constant demand for energy, it is believed to rely mostly on glucose, particularly at the level of neurons. Nonetheless, this has been challenged by studies that show that alternatives such as lactate, ketone bodies, and glutamate can be used as fuels to sustain neuronal activity. The importance of fatty acid (FA) metabolism to this extent is still unclear, albeit sustaining a significant energetic output when compared to glucose. While several authors postulate a possible role of FA for the energetic homeostasis of the brain, several others point out the intrinsic features of this pathway that make its contribution difficult to explain in the context of neuronal bioenergetics. Moreover, fueling preference at the synapse level is yet to be uncovered. In this review, we discuss in detail the arguments for and against the brain usage of FA. Furthermore, we postulate that the importance of this fuel may be greater at the synapse, where local mitochondria possess a set of features that enable a more effective usage of this fuel source.
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Affiliation(s)
- Bernardo C Antunes
- Instituto de Medicina Molecular-João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal; (B.C.A.); (T.M.)
| | - Tomás Mateus
- Instituto de Medicina Molecular-João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal; (B.C.A.); (T.M.)
| | - Vanessa A Morais
- Instituto de Medicina Molecular-João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisbon, Portugal; (B.C.A.); (T.M.)
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Cuellar-Santoyo AO, Ruiz-Rodríguez VM, Mares-Barbosa TB, Patrón-Soberano A, Howe AG, Portales-Pérez DP, Miquelajáuregui Graf A, Estrada-Sánchez AM. Revealing the contribution of astrocytes to glutamatergic neuronal transmission. Front Cell Neurosci 2023; 16:1037641. [PMID: 36744061 PMCID: PMC9893894 DOI: 10.3389/fncel.2022.1037641] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 12/20/2022] [Indexed: 01/20/2023] Open
Abstract
Research on glutamatergic neurotransmission has focused mainly on the function of presynaptic and postsynaptic neurons, leaving astrocytes with a secondary role only to ensure successful neurotransmission. However, recent evidence indicates that astrocytes contribute actively and even regulate neuronal transmission at different levels. This review establishes a framework by comparing glutamatergic components between neurons and astrocytes to examine how astrocytes modulate or otherwise influence neuronal transmission. We have included the most recent findings about the role of astrocytes in neurotransmission, allowing us to understand the complex network of neuron-astrocyte interactions. However, despite the knowledge of synaptic modulation by astrocytes, their contribution to specific physiological and pathological conditions remains to be elucidated. A full understanding of the astrocyte's role in neuronal processing could open fruitful new frontiers in the development of therapeutic applications.
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Affiliation(s)
- Ares Orlando Cuellar-Santoyo
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
| | - Victor Manuel Ruiz-Rodríguez
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
| | - Teresa Belem Mares-Barbosa
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
- Translational and Molecular Medicine Laboratory, Research Center for Health Sciences and Biomedicine, Autonomous University of San Luis Potosí, San Luis Potosí, Mexico
| | - Araceli Patrón-Soberano
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
| | - Andrew G. Howe
- Intelligent Systems Laboratory, HRL Laboratories, LLC, Malibu, CA, United States
| | - Diana Patricia Portales-Pérez
- Translational and Molecular Medicine Laboratory, Research Center for Health Sciences and Biomedicine, Autonomous University of San Luis Potosí, San Luis Potosí, Mexico
| | | | - Ana María Estrada-Sánchez
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
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Xu F, Shi J, Qin X, Zheng Z, Chen M, Lin Z, Ye J, Li M. Hormone-Glutamine Metabolism: A Critical Regulatory Axis in Endocrine-Related Cancers. Int J Mol Sci 2022; 23:ijms231710086. [PMID: 36077501 PMCID: PMC9456462 DOI: 10.3390/ijms231710086] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 08/30/2022] [Accepted: 08/30/2022] [Indexed: 11/16/2022] Open
Abstract
The endocrine-related cancers and hormones are undoubtedly highly interconnected. How hormones support or repress tumor induction and progression has been extensively profiled. Furthermore, advances in understanding the role of glutamine metabolism in mediating tumorigenesis and development, coupled with these in-depth studies on hormone (e.g., estrogen, progesterone, androgen, prostaglandin, thyroid hormone, and insulin) regulation of glutamine metabolism, have led us to think about the relationship between these three factors, which remains to be elucidated. Accordingly, in this review, we present an updated overview of glutamine metabolism traits and its influence on endocrine oncology, as well as its upstream hormonal regulation. More importantly, this hormone/glutamine metabolism axis may help in the discovery of novel therapeutic strategies for endocrine-related cancer.
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Affiliation(s)
- Fengyuan Xu
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jialu Shi
- Department of Gynecology, Hospital of Obstetrics and Gynecology, Shanghai Medical School, Fudan University, Shanghai 200010, China
| | - Xueyun Qin
- Laboratory for Reproductive Immunology, Hospital of Obstetrics and Gynecology, Shanghai Medical School, Fudan University, Shanghai 200080, China
| | - Zimeng Zheng
- Laboratory for Reproductive Immunology, Hospital of Obstetrics and Gynecology, Shanghai Medical School, Fudan University, Shanghai 200080, China
| | - Min Chen
- Laboratory for Reproductive Immunology, Hospital of Obstetrics and Gynecology, Shanghai Medical School, Fudan University, Shanghai 200080, China
| | - Zhi Lin
- Department of Gynecology, Hospital of Obstetrics and Gynecology, Shanghai Medical School, Fudan University, Shanghai 200010, China
| | - Jiangfeng Ye
- Institute for Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore 138632, Singapore
| | - Mingqing Li
- Laboratory for Reproductive Immunology, Hospital of Obstetrics and Gynecology, Shanghai Medical School, Fudan University, Shanghai 200080, China
- NHC Key Lab. of Reproduction Regulation, Shanghai Institute for Biomedical and Pharmaceutical Technologies, Fudan University, Shanghai 201203, China
- Correspondence:
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4
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Terumitsu M, Takado Y, Fukuda KI, Kato E, Tanaka S. Neurometabolite Levels and Relevance to Central Sensitization in Chronic Orofacial Pain Patients: A Magnetic Resonance Spectroscopy Study. J Pain Res 2022; 15:1421-1432. [PMID: 35599974 PMCID: PMC9122062 DOI: 10.2147/jpr.s362793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/06/2022] [Indexed: 01/08/2023] Open
Abstract
Background Patients and Methods Results Conclusion
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Affiliation(s)
- Makoto Terumitsu
- Division of Dental Anesthesiology, Department of Human Biology and Pathophysiology, Health Sciences University of Hokkaido, Hokkaido, Japan
- Division of Special Needs Dentistry and Orofacial Pain, Department of Oral Health and Clinical Science, Tokyo Dental College, Tokyo, Japan
- Correspondence: Makoto Terumitsu, Division of Dental Anesthesiology, Department of Human Biology and Pathophysiology, Health Sciences University of Hokkaido, 1757 Kanazawa, Tobetsu-cho, Ishikari-gun, Hokkaido, 061-0293, Japan, Tel/Fax +81 133 23 1445, Email
| | - Yuhei Takado
- Department of Functional Brain Imaging, Institute of Quantum Medical Sciences, National Institutes for Quantum Science and Technology, Chiba, Japan
| | - Ken-Ichi Fukuda
- Division of Special Needs Dentistry and Orofacial Pain, Department of Oral Health and Clinical Science, Tokyo Dental College, Tokyo, Japan
| | - Eisuke Kato
- Division of Special Needs Dentistry and Orofacial Pain, Department of Oral Health and Clinical Science, Tokyo Dental College, Tokyo, Japan
| | - Sei Tanaka
- Department of Oral and Maxillofacial Surgery, Tokyo Dental College, Tokyo, Japan
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Harutyunyan AA, Harutyunyan HA, Yenkoyan KB. Novel Probable Glance at Inflammatory Scenario Development in Autistic Pathology. Front Psychiatry 2021; 12:788779. [PMID: 35002805 PMCID: PMC8727757 DOI: 10.3389/fpsyt.2021.788779] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 11/17/2021] [Indexed: 12/26/2022] Open
Abstract
Autism Spectrum Disorder (ASD) is characterized by persistent deficits in social communication and restricted-repetitive patterns of behavior, interests, or activities. ASD is generally associated with chronic inflammatory states, which are linked to immune system dysfunction and/or hyperactivation. The latter might be considered as one of the factors damaging neuronal cells. Several cell types trigger and sustain such neuroinflammation. In this study, we traced different markers of immune system activation on both cellular (immune cell phenotypes) and mediatory levels (production of cytokines) alongside adverse hematology and biochemistry screening in a group of autistic children. In addition, we analyzed the main metabolic pathways potentially involved in ASD development: energy (citric acid cycle components), porphyrin, and neurotransmitter metabolism. Several ASD etiological factors, like heavy metal intoxication, and risk factors-genetic polymorphisms of the relevant neurotransmitters and vitamin D receptors-were also analyzed. Finally, broad linear regression analysis allowed us to elucidate the possible scenario that led to the development of chronic inflammation in ASD patients. Obtained data showed elevated levels of urinary cis-aconitate, isocitrate, alfa-ketoglutarate, and HMG. There were no changes in levels of metabolites of monoamine neurotransmitters, however, the liver-specific tryptophan kinurenine pathway metabolites showed increased levels of quinolinate (QUIN) and picolinate, whereas the level of kynurenate remained unchanged. Abovementioned data demonstrate the infringement in energy metabolism. We found elevated levels of lead in red blood cells, as well as altered porphyrin metabolism, which support the etiological role of heavy metal intoxication in ASD. Lead intoxication, the effect of which is intensified by a mutation of the VDR-Taq and MAO-A, leads to quinolinic acid increase, resulting in energy metabolism depletion and mitochondrial dysfunction. Moreover, our data backing the CD4+CD3+ T-cell dependence of mitochondrial dysfunction development in ASD patients reported in our previous study leads us to the conclusion that redox-immune cross-talk is considered a main functional cell damaging factor in ASD patients.
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Affiliation(s)
- Aida A. Harutyunyan
- Department of Biochemistry, Yerevan State Medical University After Mkhitar Heratsi, Yerevan, Armenia
| | - Hayk A. Harutyunyan
- Laboratory of Neuroscience, Cobrain Center, Yerevan State Medical University After Mkhitar Heratsi, Yerevan, Armenia
| | - Konstantin B. Yenkoyan
- Department of Biochemistry, Yerevan State Medical University After Mkhitar Heratsi, Yerevan, Armenia
- Laboratory of Neuroscience, Cobrain Center, Yerevan State Medical University After Mkhitar Heratsi, Yerevan, Armenia
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Maly IV, Morales MJ, Pletnikov MV. Astrocyte Bioenergetics and Major Psychiatric Disorders. ADVANCES IN NEUROBIOLOGY 2021; 26:173-227. [PMID: 34888836 DOI: 10.1007/978-3-030-77375-5_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ongoing research continues to add new elements to the emerging picture of involvement of astrocyte energy metabolism in the pathophysiology of major psychiatric disorders, including schizophrenia, mood disorders, and addictions. This review outlines what is known about the energy metabolism in astrocytes, the most numerous cell type in the brain, and summarizes the recent work on how specific perturbations of astrocyte bioenergetics may contribute to the neuropsychiatric conditions. The role of astrocyte energy metabolism in mental health and disease is reviewed on the organism, organ, and cell level. Data arising from genomic, metabolomic, in vitro, and neurobehavioral studies is critically analyzed to suggest future directions in research and possible metabolism-focused therapeutic interventions.
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Affiliation(s)
- Ivan V Maly
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, State University of New York, Buffalo, NY, USA
| | - Michael J Morales
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, State University of New York, Buffalo, NY, USA
| | - Mikhail V Pletnikov
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, State University of New York, Buffalo, NY, USA.
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Liang L, Huang Z, Li N, Wang D, Ding L, Shi H, Hong M. Effects of ammonia exposure on antioxidant function, immune response and NF-κB pathway in Chinese Strip-necked Turtle (Mauremys sinensis). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 229:105621. [PMID: 33129562 DOI: 10.1016/j.aquatox.2020.105621] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/29/2020] [Accepted: 08/31/2020] [Indexed: 06/11/2023]
Abstract
As one of the main toxic substances in aquaculture water, ammonia causes seriously physiological harm to aquatic animals. In order to investigate the effects of ammonia exposure on the antioxidant defense, immune response, and NF-κB signaling pathway in Chinese Strip-necked Turtle (Mauremys sinensis), we designed two experimental groups (control and 6.45 mM ammonia), and sampled at 6 h, 24 h, 48 h, re 24 h (recover 24 h), and re 48 h. The results showed that the blood ammonia (BA) content was significantly increased when the turtles were subjected to ammonia, and the activities of cholinesterase (CHE) and aspartate aminotransferase (AST) in the serum also showed a significant upward trend. The malondialdehyde (MDA) content continuously increased during ammonia exposure, and more than doubled at 48 h compared with the control group. The activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), catalase (CAT) and their corresponding relative mRNA expression levels in the liver during ammonia exposure were obviously increased when compared to the control group, but most decreased to the normal levels at re 48 h. In addition, the relative mRNA and protein expression levels of NF-E2 related factor 2 (Nrf2) showed similar up-regulation patterns to antioxidase during ammonia exposed periods; whereas kelch-like ECH-binding protein 1 (Keap1), as Nrf2 negative regulator, showed opposite patterns. Moreover, the relative mRNA expression levels of heat shock proteins (HSP70, HSP90) significantly elevated upon the exposure of ammonia. Furthermore, ammonia increased the relative mRNA and protein expression levels of p50 and p65 at different exposed times. The reative mRNA expression levels of immune cytokines (BAFF and IL-6) were upregulated during ammonia exposured time, while there was a decline but did not return to normal levels, in the recovery periods. Taken together, these results indicated that antioxidation, immunity, and NF-κB signaling played a certain protective role for Mauremys sinensis under ammonia exposure. Our results will be helpful to understand the mechanism of aquatic toxicology induced by ammonia in turtles.
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Affiliation(s)
- Lingyue Liang
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Zubin Huang
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Na Li
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Dongmei Wang
- Tropical Biological Technology Research Institute, Chinese Academy of Tropical Agriculture Science, Haikou 571101, China
| | - Li Ding
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China.
| | - Haitao Shi
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Meiling Hong
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China.
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8
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Prabhu VV, Nguyen TB, Cui Y, Oh YE, Piao YH, Baek HM, Kim JY, Shin KH, Kim JH, Lee KH, Chung YC. Metabolite signature associated with stress susceptibility in socially defeated mice. Brain Res 2019; 1708:171-180. [DOI: 10.1016/j.brainres.2018.12.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 11/13/2018] [Accepted: 12/15/2018] [Indexed: 01/10/2023]
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9
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Fedorovich SV, Waseem TV, Puchkova LV. Biogenetic and morphofunctional heterogeneity of mitochondria: the case of synaptic mitochondria. Rev Neurosci 2017; 28:363-373. [DOI: 10.1515/revneuro-2016-0077] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 12/29/2016] [Indexed: 12/26/2022]
Abstract
AbstractThe mitochondria of different cells are different in their morphological and biochemical properties. These organelles generate free radicals during activity, leading inevitably to mitochondrial DNA damage. It is not clear how this problem is addressed in long-lived cells, such as neurons. We propose the hypothesis that mitochondria within the same cell also differ in lifespan and ability to divide. According to our suggestion, cells have a pool of ‘stem’ mitochondria with low metabolic activity and a pool of ‘differentiated’ mitochondria with significantly shorter lifespans and high metabolic activity. We consider synaptic mitochondria as a possible example of ‘differentiated’ mitochondria. They are significantly smaller than mitochondria from the cell body, and they are different in key enzyme activity levels, proteome, and lipidome. Synaptic mitochondria are more sensitive to different damaging factors. It has been established that neurons have a sorting mechanism that sends mitochondria with high membrane potential to presynaptic endings. This review describes the properties of synaptic mitochondria and their role in the regulation of synaptic transmission.
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Affiliation(s)
- Sergei V. Fedorovich
- Institute of Biophysics and Cell Engineering, Akademicheskaya St., 27, Minsk 220072, Belarus
| | - Tatyana V. Waseem
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK
| | - Ludmila V. Puchkova
- Peter the Great St. Petersburg Polytechnic University, Polytechnicheskaya str., 29, St. Petersburg 195251, Russia
- ITMO University, Kronverksky av., 49, St.Petersburg 197101, Russia
- Institute of Experimental Medicine, Pavlova str., 12, St.Petersburg 197376, Russia
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Hertz L, Rothman DL. Glutamine-Glutamate Cycle Flux Is Similar in Cultured Astrocytes and Brain and Both Glutamate Production and Oxidation Are Mainly Catalyzed by Aspartate Aminotransferase. BIOLOGY 2017; 6:biology6010017. [PMID: 28245547 PMCID: PMC5372010 DOI: 10.3390/biology6010017] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 02/06/2017] [Accepted: 02/14/2017] [Indexed: 01/15/2023]
Abstract
The glutamine-glutamate cycle provides neurons with astrocyte-generated glutamate/γ-aminobutyric acid (GABA) and oxidizes glutamate in astrocytes, and it returns released transmitter glutamate/GABA to neurons after astrocytic uptake. This review deals primarily with the glutamate/GABA generation/oxidation, although it also shows similarity between metabolic rates in cultured astrocytes and intact brain. A key point is identification of the enzyme(s) converting astrocytic α-ketoglutarate to glutamate and vice versa. Most experiments in cultured astrocytes, including those by one of us, suggest that glutamate formation is catalyzed by aspartate aminotransferase (AAT) and its degradation by glutamate dehydrogenase (GDH). Strongly supported by results shown in Table 1 we now propose that both reactions are primarily catalyzed by AAT. This is possible because the formation occurs in the cytosol and the degradation in mitochondria and they are temporally separate. High glutamate/glutamine concentrations abolish the need for glutamate production from α-ketoglutarate and due to metabolic coupling between glutamate synthesis and oxidation these high concentrations render AAT-mediated glutamate oxidation impossible. This necessitates the use of GDH under these conditions, shown by insensitivity of the oxidation to the transamination inhibitor aminooxyacetic acid (AOAA). Experiments using lower glutamate/glutamine concentration show inhibition of glutamate oxidation by AOAA, consistent with the coupled transamination reactions described here.
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Affiliation(s)
- Leif Hertz
- Laboratory of Brain Metabolic Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Liaoning 110000, China.
| | - Douglas L Rothman
- Magnetic Resonance Research Center, Radiology and Biomedical Engineering, Yale University, New Haven, CT 06520, USA.
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Patel AB, Lai JCK, Chowdhury GIM, Rothman DL, Behar KL. Comparison of Glutamate Turnover in Nerve Terminals and Brain Tissue During [1,6- 13C 2]Glucose Metabolism in Anesthetized Rats. Neurochem Res 2016; 42:173-190. [PMID: 28025798 DOI: 10.1007/s11064-016-2103-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 11/06/2016] [Accepted: 11/08/2016] [Indexed: 01/05/2023]
Abstract
The 13C turnover of neurotransmitter amino acids (glutamate, GABA and aspartate) were determined from extracts of forebrain nerve terminals and brain homogenate, and fronto-parietal cortex from anesthetized rats undergoing timed infusions of [1,6-13C2]glucose or [2-13C]acetate. Nerve terminal 13C fractional labeling of glutamate and aspartate was lower than those in whole cortical tissue at all times measured (up to 120 min), suggesting either the presence of a constant dilution flux from an unlabeled substrate or an unlabeled (effectively non-communicating on the measurement timescale) glutamate pool in the nerve terminals. Half times of 13C labeling from [1,6-13C2]glucose, as estimated by least squares exponential fitting to the time course data, were longer for nerve terminals (GluC4, 21.8 min; GABAC2 21.0 min) compared to cortical tissue (GluC4, 12.4 min; GABAC2, 14.5 min), except for AspC3, which was similar (26.5 vs. 27.0 min). The slower turnover of glutamate in the nerve terminals (but not GABA) compared to the cortex may reflect selective effects of anesthesia on activity-dependent glucose use, which might be more pronounced in the terminals. The 13C labeling ratio for glutamate-C4 from [2-13C]acetate over that of 13C-glucose was twice as large in nerve terminals compared to cortex, suggesting that astroglial glutamine under the 13C glucose infusion was the likely source of much of the nerve terminal dilution. The net replenishment of most of the nerve terminal amino acid pools occurs directly via trafficking of astroglial glutamine.
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Affiliation(s)
- Anant B Patel
- Department of Diagnostic Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, 06520, USA. .,CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India.
| | - James C K Lai
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, Idaho State University, Pocatello, ID, 83209, USA
| | - Golam I M Chowdhury
- Department of Psychiatry, Magnetic Resonance Research Center, Yale University School of Medicine, 300 Cedar Street, PO Box 208043, New Haven, CT, 06520, USA
| | - Douglas L Rothman
- Department of Diagnostic Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Kevin L Behar
- Department of Psychiatry, Magnetic Resonance Research Center, Yale University School of Medicine, 300 Cedar Street, PO Box 208043, New Haven, CT, 06520, USA.
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Contreras L, Rial E, Cerdan S, Satrustegui J. Uncoupling Protein 2 (UCP2) Function in the Brain as Revealed by the Cerebral Metabolism of (1–13C)-Glucose. Neurochem Res 2016; 42:108-114. [DOI: 10.1007/s11064-016-1999-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 06/30/2016] [Accepted: 07/02/2016] [Indexed: 12/15/2022]
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Glucose, Lactate, β-Hydroxybutyrate, Acetate, GABA, and Succinate as Substrates for Synthesis of Glutamate and GABA in the Glutamine-Glutamate/GABA Cycle. ADVANCES IN NEUROBIOLOGY 2016; 13:9-42. [PMID: 27885625 DOI: 10.1007/978-3-319-45096-4_2] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The glutamine-glutamate/GABA cycle is an astrocytic-neuronal pathway transferring precursors for transmitter glutamate and GABA from astrocytes to neurons. In addition, the cycle carries released transmitter back to astrocytes, where a minor fraction (~25 %) is degraded (requiring a similar amount of resynthesis) and the remainder returned to the neurons for reuse. The flux in the cycle is intense, amounting to the same value as neuronal glucose utilization rate or 75-80 % of total cortical glucose consumption. This glucose:glutamate ratio is reduced when high amounts of β-hydroxybutyrate are present, but β-hydroxybutyrate can at most replace 60 % of glucose during awake brain function. The cycle is initiated by α-ketoglutarate production in astrocytes and its conversion via glutamate to glutamine which is released. A crucial reaction in the cycle is metabolism of glutamine after its accumulation in neurons. In glutamatergic neurons all generated glutamate enters the mitochondria and its exit to the cytosol occurs in a process resembling the malate-aspartate shuttle and therefore requiring concomitant pyruvate metabolism. In GABAergic neurons one half enters the mitochondria, whereas the other one half is released directly from the cytosol. A revised concept is proposed for the synthesis and metabolism of vesicular and nonvesicular GABA. It includes the well-established neuronal GABA reuptake, its metabolism, and use for resynthesis of vesicular GABA. In contrast, mitochondrial glutamate is by transamination to α-ketoglutarate and subsequent retransamination to releasable glutamate essential for the transaminations occurring during metabolism of accumulated GABA and subsequent resynthesis of vesicular GABA.
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Abstract
Transient multienzyme and/or multiprotein complexes (metabolons) direct substrates toward specific pathways and can significantly influence the metabolism of glutamate and glutamine in the brain. Glutamate is the primary excitatory neurotransmitter in brain. This neurotransmitter has essential roles in normal brain function including learning and memory. Metabolism of glutamate involves the coordinated activity of astrocytes and neurons and high affinity transporter proteins that are selectively distributed on these cells. This chapter describes known and possible metabolons that affect the metabolism of glutamate and related compounds in the brain, as well as some factors that can modulate the association and dissociation of such complexes, including protein modifications by acylation reactions (e.g., acetylation, palmitoylation, succinylation, SUMOylation, etc.) of specific residues. Development of strategies to modulate transient multienzyme and/or enzyme-protein interactions may represent a novel and promising therapeutic approach for treatment of diseases involving dysregulation of glutamate metabolism.
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Ochwanowska E, Witek B, Tymińska-Tkacz T, Sito A, Prokop A, Piotrowicz M, Liedke P. Zmiany w aktywności podstawowych parametrów biochemicznych wskazujących na nadmierne spożycie alkoholu. ALCOHOLISM AND DRUG ADDICTION 2015. [DOI: 10.1016/j.alkona.2015.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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16
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Nissen JD, Pajęcka K, Stridh MH, Skytt DM, Waagepetersen HS. Dysfunctional TCA-Cycle Metabolism in Glutamate Dehydrogenase Deficient Astrocytes. Glia 2015. [DOI: 10.1002/glia.22895] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Jakob D. Nissen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Kamilla Pajęcka
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Malin H. Stridh
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Dorte M. Skytt
- 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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McKenna MC, Rae CD. A new role for α-ketoglutarate dehydrogenase complex: regulating metabolism through post-translational modification of other enzymes. J Neurochem 2015; 134:3-6. [PMID: 26052752 DOI: 10.1111/jnc.13150] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 04/28/2015] [Accepted: 04/28/2015] [Indexed: 12/26/2022]
Abstract
This Editorial highlights a study by Gibson et al. published in this issue of JNeurochem, in which the authors reveal a novel role for the α-ketoglutarate dehydrogenase complex (KGDHC) in post-translational modification of proteins. KGDHC may catalyze post-translational modification of itself as well as several other proteins by succinylation of lysine residues. The authors' report of an enzyme responsible for succinylation of key mitochondrial enzymes represents a major step toward our understanding of the complex functional metabolome. TCA, tricarboxylic acid; KG, α-ketoglutarate; KGDHC, α-ketoglutarate dehydrogenase complex; FUM, fumarase; MDH, malate dehydrogenase; ME, malic enzyme; GDH, glutamate dehydrogenase; AAT, aspartate aminotransferase; GS, glutamine synthetase; PAG, phosphate-activated glutaminase; SIRT3, silent information regulator 3; SIRT5, silent information regulator 5.
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Affiliation(s)
- Mary C McKenna
- Department of Pediatrics and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Caroline D Rae
- Neuroscience Research Australia and School of Medical Sciences UNSW, Randwick, NSW, Australia
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Fatty acids in energy metabolism of the central nervous system. BIOMED RESEARCH INTERNATIONAL 2014; 2014:472459. [PMID: 24883315 PMCID: PMC4026875 DOI: 10.1155/2014/472459] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 03/29/2014] [Accepted: 03/29/2014] [Indexed: 12/13/2022]
Abstract
In this review, we analyze the current hypotheses regarding energy metabolism in the neurons and astroglia. Recently, it was shown that up to 20% of the total brain's energy is provided by mitochondrial oxidation of fatty acids. However, the existing hypotheses consider glucose, or its derivative lactate, as the only main energy substrate for the brain. Astroglia metabolically supports the neurons by providing lactate as a substrate for neuronal mitochondria. In addition, a significant amount of neuromediators, glutamate and GABA, is transported into neurons and also serves as substrates for mitochondria. Thus, neuronal mitochondria may simultaneously oxidize several substrates. Astrocytes have to replenish the pool of neuromediators by synthesis de novo, which requires large amounts of energy. In this review, we made an attempt to reconcile β-oxidation of fatty acids by astrocytic mitochondria with the existing hypothesis on regulation of aerobic glycolysis. We suggest that, under condition of neuronal excitation, both metabolic pathways may exist simultaneously. We provide experimental evidence that isolated neuronal mitochondria may oxidize palmitoyl carnitine in the presence of other mitochondrial substrates. We also suggest that variations in the brain mitochondrial metabolic phenotype may be associated with different mtDNA haplogroups.
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Oikawa S, Kobayashi H, Kitamura Y, Zhu H, Obata K, Minabe Y, Dazortsava M, Ohashi K, Tada-Oikawa S, Takahashi H, Yata K, Murata M, Yamashima T. Proteomic analysis of carbonylated proteins in the monkey substantia nigra after ischemia-reperfusion. Free Radic Res 2014; 48:694-705. [DOI: 10.3109/10715762.2014.901509] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Shinji Oikawa
- Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine,
Mie, Japan
| | - Hatasu Kobayashi
- Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine,
Mie, Japan
| | - Yuki Kitamura
- Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine,
Mie, Japan
| | - Hong Zhu
- Departments of Restorative Neurosurgery and Psychiatry, Kanazawa University Graduate School of Medical Science,
Kanazawa, Japan
| | - Kumi Obata
- Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine,
Mie, Japan
| | - Yoshio Minabe
- Departments of Restorative Neurosurgery and Psychiatry, Kanazawa University Graduate School of Medical Science,
Kanazawa, Japan
| | - Maryia Dazortsava
- Departments of Restorative Neurosurgery and Psychiatry, Kanazawa University Graduate School of Medical Science,
Kanazawa, Japan
| | - Kyoko Ohashi
- Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine,
Mie, Japan
| | - Saeko Tada-Oikawa
- Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine,
Mie, Japan
| | - Hitoshi Takahashi
- Department of Pathology, Brain Research Institute, University of Niigata,
Niigata, Japan
| | - Kenichiro Yata
- Department of Neurology, Mie University Graduate School of Medicine,
Mie, Japan
| | - Mariko Murata
- Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine,
Mie, Japan
| | - Tetsumori Yamashima
- Departments of Restorative Neurosurgery and Psychiatry, Kanazawa University Graduate School of Medical Science,
Kanazawa, Japan
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Schousboe A, Scafidi S, Bak LK, Waagepetersen HS, McKenna MC. Glutamate metabolism in the brain focusing on astrocytes. ADVANCES IN NEUROBIOLOGY 2014; 11:13-30. [PMID: 25236722 DOI: 10.1007/978-3-319-08894-5_2] [Citation(s) in RCA: 249] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Metabolism of glutamate, the main excitatory neurotransmitter and precursor of GABA, is exceedingly complex and highly compartmentalized in brain. Maintenance of these neurotransmitter pools is strictly dependent on the de novo synthesis of glutamine in astrocytes which requires both the anaplerotic enzyme pyruvate carboxylase and glutamine synthetase. Glutamate is formed directly from glutamine by deamidation via phosphate activated glutaminase a reaction that also yields ammonia. Glutamate plays key roles linking carbohydrate and amino acid metabolism via the tricarboxylic acid (TCA) cycle, as well as in nitrogen trafficking and ammonia homeostasis in brain. The anatomical specialization of astrocytic endfeet enables these cells to rapidly and efficiently remove neurotransmitters from the synaptic cleft to maintain homeostasis, and to provide glutamine to replenish neurotransmitter pools in both glutamatergic and GABAergic neurons. Since the glutamate-glutamine cycle is an open cycle that actively interfaces with other pathways, the de novo synthesis of glutamine in astrocytes helps to maintain the operation of this cycle. The fine-tuned biochemical specialization of astrocytes allows these cells to respond to subtle changes in neurotransmission by dynamically adjusting their anaplerotic and glycolytic activities, and adjusting the amount of glutamate oxidized for energy relative to direct formation of glutamine, to meet the demands for maintaining neurotransmission. This chapter summarizes the evidence that astrocytes are essential and dynamic partners in both glutamatergic and GABAergic neurotransmission in brain.
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Affiliation(s)
- Arne Schousboe
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen, 2100, Copenhagen, Denmark
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21
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Stobart JL, Anderson CM. Multifunctional role of astrocytes as gatekeepers of neuronal energy supply. Front Cell Neurosci 2013; 7:38. [PMID: 23596393 PMCID: PMC3622037 DOI: 10.3389/fncel.2013.00038] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 03/26/2013] [Indexed: 01/01/2023] Open
Abstract
Dynamic adjustments to neuronal energy supply in response to synaptic activity are critical for neuronal function. Glial cells known as astrocytes have processes that ensheath most central synapses and express G-protein-coupled neurotransmitter receptors and transporters that respond to neuronal activity. Astrocytes also release substrates for neuronal oxidative phosphorylation and have processes that terminate on the surface of brain arterioles and can influence vascular smooth muscle tone and local blood flow. Membrane receptor or transporter-mediated effects of glutamate represent a convergence point of astrocyte influence on neuronal bioenergetics. Astrocytic glutamate uptake drives glycolysis and subsequent shuttling of lactate from astrocytes to neurons for oxidative metabolism. Astrocytes also convert synaptically reclaimed glutamate to glutamine, which is returned to neurons for glutamate salvage or oxidation. Finally, astrocytes store brain energy currency in the form of glycogen, which can be mobilized to produce lactate for neuronal oxidative phosphorylation in response to glutamatergic neurotransmission. These mechanisms couple synaptically driven astrocytic responses to glutamate with release of energy substrates back to neurons to match demand with supply. In addition, astrocytes directly influence the tone of penetrating brain arterioles in response to glutamatergic neurotransmission, coordinating dynamic regulation of local blood flow. We will describe the role of astrocytes in neurometabolic and neurovascular coupling in detail and discuss, in turn, how astrocyte dysfunction may contribute to neuronal bioenergetic deficit and neurodegeneration. Understanding the role of astrocytes as a hub for neurometabolic and neurovascular coupling mechanisms is a critical underpinning for therapeutic development in a broad range of neurodegenerative disorders characterized by chronic generalized brain ischemia and brain microvascular dysfunction.
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Affiliation(s)
- Jillian L Stobart
- Division of Neurodegenerative Disorders, Department of Pharmacology and Therapeutics, St. Boniface Hospital Research, University of Manitoba Winnipeg, MB, Canada ; Department of Nuclear Medicine, Institute of Pharmacology and Toxicology, University of Zürich Zürich, Switzerland
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McKenna MC. Substrate competition studies demonstrate oxidative metabolism of glucose, glutamate, glutamine, lactate and 3-hydroxybutyrate in cortical astrocytes from rat brain. Neurochem Res 2012; 37:2613-26. [PMID: 23079895 DOI: 10.1007/s11064-012-0901-3] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 10/01/2012] [Accepted: 10/03/2012] [Indexed: 01/14/2023]
Abstract
It is well established that astrocytes can utilize many substrates to support oxidative energy metabolism; however, use of energy substrates in the presence of other substrates, as would occur in vivo, has not been systematically evaluated. Substrate competition studies were used to determine changes in the rates of (14)CO(2) production since little is known about the interaction of energy substrates in astrocytes. The rates of (14)CO(2) production from 1 mM D-[6-(14)C]glucose, L-[U-(14)C]glutamate, L-[U-(14)C]glutamine, D-3-hydroxy[3-(14)C]butyrate, L-[U-(14)C]lactate and L-[U-(14)C]malate by primary cultures of astrocytes from rat brain were determined to be 1.17 ± 0.19, 85.30 ± 12.25, 28.04 ± 2.84, 13.55 ± 4.56, 14.84 ± 2.40 and 5.20 ± 1.20 nmol/h/mg protein (mean ± SEM), respectively. The rate of (14)CO(2) production from glutamate oxidation was higher than that of the other substrates Addition of unlabeled glutamate significantly decreased the rates of (14)CO(2) production from all other substrates studied; however, glutamate oxidation was not altered by the addition of any of the other substrates. The rate of (14)CO(2) production of glutamine was decreased by glutamate, but not altered by other substrates. The rate of (14)CO(2) production from glucose was significantly decreased by the addition of unlabeled glutamate, glutamine or lactate, but not by 3-hydroxybutyrate or malate. Addition of unlabeled glucose did not significantly alter the (14)CO(2) production from any other substrate. (14)CO(2) production from lactate was decreased by the addition of unlabeled glutamine or glutamate and increased by addition of malate. The (14)CO(2) production from malate was decreased by the addition of unlabeled glutamate or lactate, but was not altered by the other substrates. The substrate utilization for oxidative energy metabolism in astrocytes is very different than the profile previously reported for synaptic terminals. These studies demonstrate the potential use of multiple substrates including glucose, glutamate, glutamine, lactate and 3-hydroxybutyrate as energy substrates for astrocytes. The data also provide evidence of interactions of substrates and multiple compartments of TCA cycle activity in cultured astrocytes.
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Affiliation(s)
- Mary C McKenna
- Department of Pediatrics and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA.
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Biochemical and structural characterization of mouse mitochondrial aspartate aminotransferase, a newly identified kynurenine aminotransferase-IV. Biosci Rep 2012; 31:323-32. [PMID: 20977429 DOI: 10.1042/bsr20100117] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Mammalian mAspAT (mitochondrial aspartate aminotransferase) is recently reported to have KAT (kynurenine aminotransferase) activity and plays a role in the biosynthesis of KYNA (kynurenic acid) in rat, mouse and human brains. This study concerns the biochemical and structural characterization of mouse mAspAT. In this study, mouse mAspAT cDNA was amplified from mouse brain first stand cDNA and its recombinant protein was expressed in an Escherichia coli expression system. Sixteen oxo acids were tested for the co-substrate specificity of mouse mAspAT and 14 of them were shown to be capable of serving as co-substrates for the enzyme. Structural analysis of mAspAT by macromolecular crystallography revealed that the cofactor-binding residues of mAspAT are similar to those of other KATs. The substrate-binding residues of mAspAT are slightly different from those of other KATs. Our results provide a biochemical and structural basis towards understanding the overall physiological role of mAspAT in vivo and insight into controlling the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.
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Schousboe A, Sickmann HM, Bak LK, Schousboe I, Jajo FS, Faek SAA, Waagepetersen HS. Neuron-glia interactions in glutamatergic neurotransmission: roles of oxidative and glycolytic adenosine triphosphate as energy source. J Neurosci Res 2011; 89:1926-34. [PMID: 21919035 DOI: 10.1002/jnr.22746] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 06/16/2011] [Accepted: 06/20/2011] [Indexed: 02/01/2023]
Abstract
Glutamatergic neurotransmission accounts for a considerable part of energy consumption related to signaling in the brain. Chemical energy is provided by adenosine triphosphate (ATP) formed in glycolysis and tricarboxylic acid (TCA) cycle combined with oxidative phosphorylation. It is not clear whether ATP generated in these pathways is equivalent in relation to fueling of the energy-requiring processes, i.e., vesicle filling, transport, and enzymatic processing in the glutamatergic tripartite synapse (the astrocyte and pre- and postsynapse). The role of astrocytic glycogenolysis in maintaining theses processes also has not been fully elucidated. Cultured astrocytes and neurons were utilized to monitor these processes related to glutamatergic neurotransmission. Inhibitors of glycolysis and TCA cycle in combination with pathway-selective substrates were used to study glutamate uptake and release monitored with D-aspartate. Western blotting of glyceraldehyde-3-P dehydrogenase (GAPDH) and phosphoglycerate kinase (PGK) was performed to determine whether these enzymes are associated with the cell membrane. We show that ATP formed in glycolysis is superior to that generated by oxidative phosphorylation in providing energy for glutamate uptake both in astrocytes and in neurons. The neuronal vesicular glutamate release was less dependent on glycolytic ATP. Dependence of glutamate uptake on glycolytic ATP may be at least partially explained by a close association in the membrane of GAPDH and PGK and the glutamate transporters. It may be suggested that these enzymes form a complex with the transporters and the Na(+) /K(+) -ATPase, the latter providing the sodium gradient required for the transport process.
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Affiliation(s)
- A Schousboe
- Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark
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McKenna MC. Glutamate dehydrogenase in brain mitochondria: do lipid modifications and transient metabolon formation influence enzyme activity? Neurochem Int 2011; 59:525-33. [PMID: 21771624 DOI: 10.1016/j.neuint.2011.07.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2011] [Revised: 06/30/2011] [Accepted: 07/03/2011] [Indexed: 11/17/2022]
Abstract
Metabolism of glutamate, the primary excitatory neurotransmitter in brain, is complex and of paramount importance to overall brain function. Thus, understanding the regulation of enzymes involved in formation and disposal of glutamate and related metabolites is crucial to understanding glutamate metabolism. Glutamate dehydrogenase (GDH) is a pivotal enzyme that links amino acid metabolism and TCA cycle activity in brain and other tissues. The allosteric regulation of GDH has been extensively studied and characterized. Less is known about the influence of lipid modifications on GDH activity, and the participation of GDH in transient heteroenzyme complexes (metabolons) that can greatly influence metabolism by altering kinetic parameters and lead to channeling of metabolites. This review summarizes evidence for palmitoylation and acylation of GDH, information on protein binding, and information regarding the participation of GDH in transient heteroenzyme complexes. Recent studies suggest that a number of other proteins can bind to GDH altering activity and overall metabolism. It is likely that these modifications and interactions contribute additional levels of regulation of GDH activity and glutamate metabolism.
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Affiliation(s)
- Mary C McKenna
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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26
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Han Q, Cai T, Tagle DA, Li J. Structure, expression, and function of kynurenine aminotransferases in human and rodent brains. Cell Mol Life Sci 2010; 67:353-68. [PMID: 19826765 PMCID: PMC2867614 DOI: 10.1007/s00018-009-0166-4] [Citation(s) in RCA: 170] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 09/27/2009] [Accepted: 09/29/2009] [Indexed: 01/12/2023]
Abstract
Kynurenine aminotransferases (KATs) catalyze the synthesis of kynurenic acid (KYNA), an endogenous antagonist of N-methyl-D: -aspartate and alpha 7-nicotinic acetylcholine receptors. Abnormal KYNA levels in human brains are implicated in the pathophysiology of schizophrenia, Alzheimer's disease, and other neurological disorders. Four KATs have been reported in mammalian brains, KAT I/glutamine transaminase K/cysteine conjugate beta-lyase 1, KAT II/aminoadipate aminotransferase, KAT III/cysteine conjugate beta-lyase 2, and KAT IV/glutamic-oxaloacetic transaminase 2/mitochondrial aspartate aminotransferase. KAT II has a striking tertiary structure in N-terminal part and forms a new subgroup in fold type I aminotransferases, which has been classified as subgroup Iepsilon. Knowledge regarding KATs is vast and complex; therefore, this review is focused on recent important progress of their gene characterization, physiological and biochemical function, and structural properties. The biochemical differences of four KATs, specific enzyme activity assays, and the structural insights into the mechanism of catalysis and inhibition of these enzymes are discussed.
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Affiliation(s)
- Qian Han
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061 USA
| | - Tao Cai
- OIIB, NIDCR, National Institutes of Health, Bethesda MD, 20892-4322 USA
| | - Danilo A. Tagle
- Neuroscience Center, NINDS, National Institutes of Health, Bethesda, MD 2089-29525 USA
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061 USA
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27
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Goncalves S, Paupe V, Dassa EP, Brière JJ, Favier J, Gimenez-Roqueplo AP, Bénit P, Rustin P. Rapid determination of tricarboxylic acid cycle enzyme activities in biological samples. BMC BIOCHEMISTRY 2010; 11:5. [PMID: 20109171 PMCID: PMC2823639 DOI: 10.1186/1471-2091-11-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 01/28/2010] [Indexed: 11/10/2022]
Abstract
Background In the last ten years, deficiencies in tricarboxylic acid cycle (TCAC) enzymes have been shown to cause a wide spectrum of human diseases, including malignancies and neurological and cardiac diseases. A prerequisite to the identification of disease-causing TCAC enzyme deficiencies is the availability of effective enzyme assays. Results We developed three assays that measure the full set of TCAC enzymes. One assay relies on the sequential addition of reagents to measure succinyl-CoA ligase activity, followed by succinate dehydrogenase, fumarase and, finally, malate dehydrogenase. Another assay measures the activity of α-ketoglutarate dehydrogenase followed by aconitase and isocitrate dehydrogenase. The remaining assay measures citrate synthase activity using a standard procedure. We used these assays successfully on extracts of small numbers of human cells displaying various severe or partial TCAC deficiencies and on frozen heart homogenates from heterozygous mice harboring an SDHB gene deletion. Conclusion This set of assays is rapid and simple to use and can immediately detect even partial defects, as the activity of each enzyme can be readily compared with one or more other activities measured in the same sample.
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28
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Heterogeneity of nervous system mitochondria: Location, location, location! Exp Neurol 2009; 218:293-307. [DOI: 10.1016/j.expneurol.2009.05.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Revised: 04/30/2009] [Accepted: 05/08/2009] [Indexed: 01/03/2023]
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Chambery A, Colucci-D’Amato L, Vissers JPC, Scarpella S, Langridge JI, Parente A. Proteomic Profiling of Proliferating and Differentiated Neural mes-c-myc A1 Cell Line from Mouse Embryonic Mesencephalon by LC−MS. J Proteome Res 2008; 8:227-38. [DOI: 10.1021/pr800454n] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Angela Chambery
- Dipartimento di Scienze della Vita, Seconda Università di Napoli, I-81100 Caserta, Italy, Istituto di Genetica e Biofisica “A. Buzzati-Traverso”, Consiglio Nazionale delle Ricerche, 80131-Napoli, Italy, and Waters Corporation, MS Technologies Center, M22 5PP Manchester, United Kingdom
| | - Luca Colucci-D’Amato
- Dipartimento di Scienze della Vita, Seconda Università di Napoli, I-81100 Caserta, Italy, Istituto di Genetica e Biofisica “A. Buzzati-Traverso”, Consiglio Nazionale delle Ricerche, 80131-Napoli, Italy, and Waters Corporation, MS Technologies Center, M22 5PP Manchester, United Kingdom
| | - Johannes P. C. Vissers
- Dipartimento di Scienze della Vita, Seconda Università di Napoli, I-81100 Caserta, Italy, Istituto di Genetica e Biofisica “A. Buzzati-Traverso”, Consiglio Nazionale delle Ricerche, 80131-Napoli, Italy, and Waters Corporation, MS Technologies Center, M22 5PP Manchester, United Kingdom
| | - Simona Scarpella
- Dipartimento di Scienze della Vita, Seconda Università di Napoli, I-81100 Caserta, Italy, Istituto di Genetica e Biofisica “A. Buzzati-Traverso”, Consiglio Nazionale delle Ricerche, 80131-Napoli, Italy, and Waters Corporation, MS Technologies Center, M22 5PP Manchester, United Kingdom
| | - James I. Langridge
- Dipartimento di Scienze della Vita, Seconda Università di Napoli, I-81100 Caserta, Italy, Istituto di Genetica e Biofisica “A. Buzzati-Traverso”, Consiglio Nazionale delle Ricerche, 80131-Napoli, Italy, and Waters Corporation, MS Technologies Center, M22 5PP Manchester, United Kingdom
| | - Augusto Parente
- Dipartimento di Scienze della Vita, Seconda Università di Napoli, I-81100 Caserta, Italy, Istituto di Genetica e Biofisica “A. Buzzati-Traverso”, Consiglio Nazionale delle Ricerche, 80131-Napoli, Italy, and Waters Corporation, MS Technologies Center, M22 5PP Manchester, United Kingdom
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Guo Z, Yang Q, Liu H, Liu C, Cai X. The Study of a Disposable Reagentless Biosensor for Fast Test of Aspartate Aminotransferase. ELECTROANAL 2008. [DOI: 10.1002/elan.200704165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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31
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Riera JJ, Schousboe A, Waagepetersen HS, Howarth C, Hyder F. The micro-architecture of the cerebral cortex: functional neuroimaging models and metabolism. Neuroimage 2008; 40:1436-59. [PMID: 18343162 PMCID: PMC4348032 DOI: 10.1016/j.neuroimage.2007.12.051] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 12/19/2007] [Accepted: 12/20/2007] [Indexed: 01/22/2023] Open
Abstract
In order to interpret/integrate data obtained with different functional neuroimaging modalities (e.g. fMRI, EEG/MEG, PET/SPECT, fNIRS), forward-generative models of a diversity of brain mechanisms at the mesoscopic level are considered necessary. For the cerebral cortex, the brain structure with possibly the most relevance for functional neuroimaging, a variety of such biophysical models has been proposed over the last decade. The development of technological tools to investigate in vitro the physiological, anatomical and biochemical principles at the microscopic scale in comparative studies formed the basis for such theoretical progresses. However, with the most recent introduction of systems to record electrical (e.g. miniaturized probes chronically/acutely implantable in the brain), optical (e.g. two-photon laser scanning microscopy) and atomic nuclear spectral (e.g. nuclear magnetic resonance spectroscopy) signals using living laboratory animals, the field is receiving even greater attention. Major advances have been achieved by combining such sophisticated recording systems with new experimental strategies (e.g. transgenic/knock-out animals, high resolution stereotaxic manipulation systems for probe-guidance and cellular-scale chemical-delivery). Theoreticians may now be encouraged to re-consider previously formulated mesoscopic level models in order to incorporate important findings recently made at the microscopic scale. In this series of reviews, we summarize the background at the microscopic scale, which we suggest will constitute the foundations for upcoming representations at the mesoscopic level. In this first part, we focus our attention on the nerve ending particles in order to summarize basic principles and mechanisms underlying cellular metabolism in the cerebral cortex. It will be followed by two parts highlighting major features in its organization/working-principles to regulate both cerebral blood circulation and neuronal activity, respectively. Contemporary theoretical models for functional neuroimaging will be revised in the fourth part, with particular emphasis in their applications, advantages/limitations and future prospects.
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Affiliation(s)
- Jorge J Riera
- Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
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32
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McKenna MC. The glutamate-glutamine cycle is not stoichiometric: fates of glutamate in brain. J Neurosci Res 2008; 85:3347-58. [PMID: 17847118 DOI: 10.1002/jnr.21444] [Citation(s) in RCA: 289] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although glutamate is usually thought of as the major excitatory neurotransmitter in brain, it is important to note that glutamate has many other fates in brain, including oxidation for energy, incorporation into proteins, and formation of glutamine, gamma-aminobutyric acid (GABA), and glutathione. The compartmentation of glutamate in brain cells is complex and modulated by the presence and concentration of glutamate per se as well as by other metabolites. Both astrocytes and neurons distinguish between exogenous glutamate and glutamate formed endogenously from glutamine via glutaminase. There is evidence of multiple subcellular compartments of glutamate within both neurons and astrocytes, and the carbon skeleton of glutamate can be derived from other amino acids and many energy substrates including glucose, lactate, and 3-hydroxybutyrate. Both astrocytes and neurons utilize glutamate, albeit for cell-specific metabolic fates. Glutamate is readily formed in neurons from glutamine synthesized in astrocytes, released into the extracellular space, and taken up by neurons. However, the glutamate-glutamine cycle is not a stoichiometric cycle but rather an open pathway that interfaces with many other metabolic pathways to varying extents depending on cellular requirements and priorities.
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Affiliation(s)
- Mary C McKenna
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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He S, Wang Q, He J, Pu H, Yang W, Ji J. Proteomic analysis and comparison of the biopsy and autopsy specimen of human brain temporal lobe. Proteomics 2006; 6:4987-96. [PMID: 16912969 DOI: 10.1002/pmic.200600078] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The proteomic study on human temporal lobe can help us to understand the physiological function of CNS in normal as well as in pathological state. Proteomic tools are potent for the assessment of protein stability post mortem. In this pilot study, the human temporal lobe biopsy specimen with chronic pharmacoresistant temporal lobe epilepsy (TLE) and autopsy specimen in control were separated by 2-DE. Using MALDI-TOF-MS and MS/MS, 375 protein spots were identified which were the products of 267 genes. Six down-regulated and 23 up-regulated protein spots in the autopsy specimen were ascertained after the gel image analysis with the ImageMaster software. A number of proteins that include neurotransmitter metabolic and glycolytic enzymes, cytoprotective proteins and cytoskeleton were found decreased while the precursor of apolipoprotein A-I increased in the TLE brain. We tried several methods to prepare the protein samples and found that DNase and RNase treatment, ultracentrifugation and Amersham clean-up kit purification can improve gel separation quality. This work optimized the sample preparation method and constructed a primary protein database of human temporal lobe and found some proteins with remarkable level change probably involved in the post-mortem process and chronic pharmacoresistant TLE pathogenesis.
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Affiliation(s)
- Sizhi He
- Department of Biochemistry and Molecular Biology, College of Life Sciences, National Laboratory of Protein Engineering and Plant Genetic Engineering, Peking University, Beijing, PR China
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