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Alcicek S, Pilatus U, Manzhurtsev A, Weber KJ, Ronellenfitsch MW, Steinbach JP, Hattingen E, Wenger KJ. Amino acid metabolism in glioma: in vivo MR-spectroscopic detection of alanine as a potential biomarker of poor survival in glioma patients. J Neurooncol 2024:10.1007/s11060-024-04803-2. [PMID: 39192067 DOI: 10.1007/s11060-024-04803-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2024] [Accepted: 08/10/2024] [Indexed: 08/29/2024]
Abstract
PURPOSE Reprogramming of amino acid metabolism is relevant for initiating and fueling tumor formation and growth. Therefore, there has been growing interest in anticancer therapies targeting amino acid metabolism. While developing personalized therapeutic approaches to glioma, in vivo proton magnetic resonance spectroscopy (MRS) is a valuable tool for non-invasive monitoring of tumor metabolism. Here, we evaluated MRS-detected brain amino acids and myo-inositol as potential diagnostic and prognostic biomarkers in glioma. METHOD We measured alanine, glycine, glutamate, glutamine, and myo-inositol in 38 patients with MRI-suspected glioma using short and long echo-time single-voxel PRESS MRS sequences. The detectability of alanine, glycine, and myo-inositol and the (glutamate + glutamine)/total creatine ratio were evaluated against the patients' IDH mutation status, CNS WHO grade, and overall survival. RESULTS While the detection of alanine and non-detection of myo-inositol significantly correlated with IDH wildtype (p = 0.0008, p = 0.007, respectively) and WHO grade 4 (p = 0.01, p = 0.04, respectively), glycine detection was not significantly associated with either. The ratio of (glutamate + glutamine)/total creatine was significantly higher in WHO grade 4 than in 2 and 3. We found that the overall survival was significantly shorter in glioma patients with alanine detection (p = 0.00002). CONCLUSION Focusing on amino acids in MRS can improve its diagnostic and prognostic value in glioma. Alanine, which is visible at long TE even in the presence of lipids, could be a relevant indicator for overall survival.
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Affiliation(s)
- Seyma Alcicek
- Goethe University Frankfurt, University Hospital, Institute of Neuroradiology, Schleusenweg 2-16, 60528, Frankfurt/Main, Germany.
- University Cancer Center Frankfurt (UCT), Frankfurt/Main, Germany.
- Frankfurt Cancer Institute (FCI), Frankfurt/Main, Germany.
- German Cancer Research Center (DKFZ) Heidelberg, German Cancer Consortium (DKTK), Partner Site, Frankfurt/Mainz, Germany.
| | - Ulrich Pilatus
- Goethe University Frankfurt, University Hospital, Institute of Neuroradiology, Schleusenweg 2-16, 60528, Frankfurt/Main, Germany
| | - Andrei Manzhurtsev
- Goethe University Frankfurt, University Hospital, Institute of Neuroradiology, Schleusenweg 2-16, 60528, Frankfurt/Main, Germany
| | - Katharina J Weber
- University Cancer Center Frankfurt (UCT), Frankfurt/Main, Germany
- Frankfurt Cancer Institute (FCI), Frankfurt/Main, Germany
- German Cancer Research Center (DKFZ) Heidelberg, German Cancer Consortium (DKTK), Partner Site, Frankfurt/Mainz, Germany
- Goethe University Frankfurt, University Hospital, Institute of Neurology (Edinger-Institute), Frankfurt/Main, Germany
| | - Michael W Ronellenfitsch
- University Cancer Center Frankfurt (UCT), Frankfurt/Main, Germany
- Frankfurt Cancer Institute (FCI), Frankfurt/Main, Germany
- German Cancer Research Center (DKFZ) Heidelberg, German Cancer Consortium (DKTK), Partner Site, Frankfurt/Mainz, Germany
- Goethe University Frankfurt, University Hospital, Dr. Senckenberg Institute of Neurooncology, Frankfurt/Main, Germany
| | - Joachim P Steinbach
- University Cancer Center Frankfurt (UCT), Frankfurt/Main, Germany
- Frankfurt Cancer Institute (FCI), Frankfurt/Main, Germany
- German Cancer Research Center (DKFZ) Heidelberg, German Cancer Consortium (DKTK), Partner Site, Frankfurt/Mainz, Germany
- Goethe University Frankfurt, University Hospital, Dr. Senckenberg Institute of Neurooncology, Frankfurt/Main, Germany
| | - Elke Hattingen
- Goethe University Frankfurt, University Hospital, Institute of Neuroradiology, Schleusenweg 2-16, 60528, Frankfurt/Main, Germany
- University Cancer Center Frankfurt (UCT), Frankfurt/Main, Germany
- Frankfurt Cancer Institute (FCI), Frankfurt/Main, Germany
- German Cancer Research Center (DKFZ) Heidelberg, German Cancer Consortium (DKTK), Partner Site, Frankfurt/Mainz, Germany
| | - Katharina J Wenger
- Goethe University Frankfurt, University Hospital, Institute of Neuroradiology, Schleusenweg 2-16, 60528, Frankfurt/Main, Germany
- University Cancer Center Frankfurt (UCT), Frankfurt/Main, Germany
- Frankfurt Cancer Institute (FCI), Frankfurt/Main, Germany
- German Cancer Research Center (DKFZ) Heidelberg, German Cancer Consortium (DKTK), Partner Site, Frankfurt/Mainz, Germany
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2
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Liu T, Xu Y, Hu S, Feng S, Zhang H, Zhu X, Wang C. Alanine, a potential amino acid biomarker of pediatric sepsis: a pilot study in PICU. Amino Acids 2024; 56:48. [PMID: 39060743 PMCID: PMC11281965 DOI: 10.1007/s00726-024-03408-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 07/17/2024] [Indexed: 07/28/2024]
Abstract
Sepsis is characterized by a metabolic disorder of amino acid occurs in the early stage; however, the profile of serum amino acids and their alterations associated with the onset of sepsis remain unclear. Thus, our objective is to identify the specific kinds of amino acids as diagnostic biomarkers in pediatric patients with sepsis. Serum samples were collected from patients with sepsis admitted to the pediatric intensive care unit (PICU) between January 2019 and December 2019 on the 1st, 3rd and 7th day following admission. Demographic and laboratory variables were also retrieved from the medical records specified times. Serum amino acid concentrations were detected by UPLC-MS/MS system. PLS-DA (VIP > 1.0) and Kruskal-Wallis test (p < 0.05) were employed to identify potential biomarkers. Spearman's rank correlation analysis was conducted to find the potential association between amino acid levels and clinical features. The diagnostic utility for pediatric sepsis was assessed using receiver operating characteristic (ROC) curve analysis. Most of amino acid contents in serum were significantly decreased in patients with sepsis, but approached normal levels by the seventh day post-diagnosis. Threonine (THR), lysine (LYS), valine (VAL) and alanine (ALA) emerged as potential biomarkers related for sepsis occurrence, though they were not associated with PELOD/PELOD-2 scores. Moreover, alterations in serum THR, LYS and ALA were linked to complications of brain injury, and serum ALA levels were also related to sepsis-associated acute kidney injury. Further analysis revealed that ALA was significantly correlated with the Glasgow score, serum lactate and glucose levels, C-reactive protein (CRP), and other indicators for liver or kidney dysfunction. Notably, the area under the ROC curve (AUC) for ALA in distinguishing sepsis from healthy controls was 0.977 (95% CI: 0.925-1.000). The serum amino acid profile of children with sepsis is significantly altered compared to that of healthy controls. Notably, ALA shows promise as a potential biomarker for the early diagnosis in septic children.
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Affiliation(s)
- Tiantian Liu
- Department of Critical Care Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, No. 355 Luding Road, Putuo District, Shanghai, 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200062, China
| | - Yaya Xu
- Department of Pediatric Critical Care Medicine, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China
| | - Shaohua Hu
- Department of Clinical Laboratory, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200062, China
| | - Shuyun Feng
- Department of Critical Care Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, No. 355 Luding Road, Putuo District, Shanghai, 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200062, China
| | - Hong Zhang
- Department of Clinical Laboratory, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200062, China
| | - Xiaodong Zhu
- Department of Pediatric Critical Care Medicine, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
| | - Chunxia Wang
- Department of Critical Care Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, No. 355 Luding Road, Putuo District, Shanghai, 200062, China.
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200062, China.
- Clinical Research Unit, Shanghai Children's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200062, China.
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Lu L, Kotowska AM, Kern S, Fang M, Rudd TR, Alexander MR, Scurr DJ, Zhu Z. Metabolomic and Proteomic Analysis of ApoE4-Carrying H4 Neuroglioma Cells in Alzheimer's Disease Using OrbiSIMS and LC-MS/MS. Anal Chem 2024; 96:11760-11770. [PMID: 38989551 PMCID: PMC11270533 DOI: 10.1021/acs.analchem.4c01201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 06/22/2024] [Accepted: 06/24/2024] [Indexed: 07/12/2024]
Abstract
Growing clinical evidence reveals that systematic molecular alterations in the brain occur 20 years before the onset of AD pathological features. Apolipoprotein E4 (ApoE4) is one of the most significant genetic risk factors for Alzheimer's disease (AD), which is not only associated with the AD pathological features such as amyloid-β deposition, phosphorylation of tau proteins, and neuroinflammation but is also involved in metabolism, neuron growth, and synaptic plasticity. Multiomics, such as metabolomics and proteomics, are applied widely in identifying key disease-related molecular alterations and disease-progression-related changes. Despite recent advances in the development of analytical technologies, screening the entire profile of metabolites remains challenging due to the numerous classes of compounds with diverse chemical properties that require different extraction processes for mass spectrometry. In this study, we utilized Orbitrap Secondary Ion Mass Spectrometry (OrbiSIMS) as a chemical filtering screening tool to examine molecular alterations in ApoE4-carried neuroglioma cells compared to wild-type H4 cells. The findings were compared using liquid chromatography (LC)-MS/MS targeted metabolomics analysis for the confirmation of specific metabolite classes. Detected alterations in peptide fragments by OrbiSIMS provided preliminary indications of protein changes. These were extensively analyzed through proteomics to explore ApoE4's impact on proteins. Our metabolomics approach, combining OrbiSIMS and LC-MS/MS, revealed disruptions in lipid metabolism, including glycerophospholipids and sphingolipids, as well as amino acid metabolism, encompassing alanine, aspartate, and glutamate metabolism; aminoacyl-tRNA biosynthesis; glutamine metabolism; and taurine and hypotaurine metabolism. Further LC-MS/MS proteomics studies confirmed the dysfunction in amino acid and tRNA aminoacylation metabolic processes, and highlighted RNA splicing alterations influenced by ApoE4.
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Affiliation(s)
- Li Lu
- School
of Pharmacy, The University of Nottingham University Park Campus, Nottingham NG7 2RD, U.K.
| | - Anna M. Kotowska
- School
of Pharmacy, The University of Nottingham University Park Campus, Nottingham NG7 2RD, U.K.
| | - Stefanie Kern
- School
of Pharmacy, The University of Nottingham University Park Campus, Nottingham NG7 2RD, U.K.
| | - Min Fang
- Medicines
and Healthcare products Regulatory Agency (MHRA), South Mimms, Blanche Lane EN6 3QG, U.K.
| | - Timothy R. Rudd
- Medicines
and Healthcare products Regulatory Agency (MHRA), South Mimms, Blanche Lane EN6 3QG, U.K.
| | - Morgan R. Alexander
- School
of Pharmacy, The University of Nottingham University Park Campus, Nottingham NG7 2RD, U.K.
| | - David J. Scurr
- School
of Pharmacy, The University of Nottingham University Park Campus, Nottingham NG7 2RD, U.K.
| | - Zheying Zhu
- School
of Pharmacy, The University of Nottingham University Park Campus, Nottingham NG7 2RD, U.K.
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Abstract
Amino acids derived from protein digestion are important nutrients for the growth and maintenance of organisms. Approximately half of the 20 proteinogenic amino acids can be synthesized by mammalian organisms, while the other half are essential and must be acquired from the nutrition. Absorption of amino acids is mediated by a set of amino acid transporters together with transport of di- and tripeptides. They provide amino acids for systemic needs and for enterocyte metabolism. Absorption is largely complete at the end of the small intestine. The large intestine mediates the uptake of amino acids derived from bacterial metabolism and endogenous sources. Lack of amino acid transporters and peptide transporter delays the absorption of amino acids and changes sensing and usage of amino acids by the intestine. This can affect metabolic health through amino acid restriction, sensing of amino acids, and production of antimicrobial peptides.
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Affiliation(s)
- Stefan Bröer
- Research School of Biology, Australian National University, Canberra, Australia;
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5
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Ying N, Luo H, Li B, Gong K, Shu Q, Liang F, Gao H, Huang T, Zheng H. Exercise Alleviates Behavioral Disorders but Shapes Brain Metabolism of APP/PS1 Mice in a Region- and Exercise-Specific Manner. J Proteome Res 2023. [PMID: 37126732 DOI: 10.1021/acs.jproteome.2c00691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Exercise plays a beneficial role in the management of Alzheimer's disease (AD), but its effects on brain metabolism are still far from being understood. Here, we examined behavioral changes of APP/PS1 mice after high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) and analyzed metabolomics profiles in the hippocampus, cortex, and hypothalamus by using nuclear magnetic resonance spectroscopy to explore potential metabolic mechanisms. The results demonstrate that both HIIT and MICT alleviated anxiety/depressive-like behaviors as well as learning and memory impairments of AD mice. Metabolomics analysis reveals that energy metabolism, neurotransmitter metabolism, and membrane metabolism were significantly altered in all three brain regions after both types of exercises. Amino acid metabolism was detected to be affected in the cortex and hypothalamus after HIIT and in the hippocampus and hypothalamus after MICT. However, only HIIT significantly altered astrocyte-neuron metabolism in the hippocampus and hypothalamus of AD mice. Therefore, our study suggests that exercise can shape brain metabolism of AD mice in a region- and exercise-specific manner, indicating that the precise modification of brain metabolism by a specific type of exercise might be a novel perspective for the prevention and treatment of AD.
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Affiliation(s)
- Na Ying
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Hanqi Luo
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Baixia Li
- School of Physical Education and Health Care, East China Normal University, Shanghai 200241, China
- Key Laboratory of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, East China Normal University, Shanghai 200241, China
| | - Kaiyan Gong
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Qi Shu
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Fei Liang
- College of Physical Education, Gannan Normal University, Ganzhou 341000, China
| | - Hongchang Gao
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Tao Huang
- Department of Physical Education, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hong Zheng
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
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6
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Pearl H, Fleischer CC. Association between altered metabolism and genetic mutations in human glioma. Cancer Rep (Hoboken) 2023; 6:e1799. [PMID: 36916606 PMCID: PMC10172161 DOI: 10.1002/cnr2.1799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 02/20/2023] [Accepted: 02/24/2023] [Indexed: 03/15/2023] Open
Abstract
BACKGROUND Molecular markers for classification of gliomas include isocitrate dehydrogenase (IDH) mutations and codeletion of chromosomal arms 1p and 19q (1p/19q). While mutations in IDH enzymes result in the well-characterized production of oncometabolite 2-hydroxyglutarate, dysregulation of other metabolites in IDH tumors is less characterized. Similarly, the effects of 1p/19q codeletion on cellular metabolism are also unclear. AIM This study aimed to quantify changes in tumor metabolites in human glioma tissue as a function of both IDH mutation and 1p/19q codeletion. METHODS AND RESULTS Deidentified human glioma tissue and associated clinical data were obtained from the Emory University Winship Cancer Institute tissue biobank from 14 patients (WHO grades II, III, and IV; seven female and seven male). Proton (1 H) high-resolution magic angle spinning (HR-MAS) nuclear magnetic resonance (NMR) spectroscopy data were acquired using a 600 MHz Bruker AVANCE III NMR spectrometer. Metabolite concentrations were calculated using LCModel. Differences in metabolite concentrations as a function of IDH mutation, 1p/19q codeletion, and survival status were determined using Mann-Whitney U tests. Concentrations of alanine, glutamine, and glutamate were significantly lower in glioma tissue with IDH mutations compared to tissue with IDH wildtype. Additionally, glutamate concentration was significantly lower in glioma tissue with 1p/19q codeletion compared to intact 1p/19q. Exploratory analysis revealed alanine concentration varied significantly as a function of survival status. CONCLUSIONS Given the emerging landscape of glioma treatments that target metabolic dysregulation, an improved understanding of altered metabolism in molecular sub-types of gliomas, including those with IDH mutation and 1p/19q codeletion, is an important consideration for treatment stratification and personalized medicine.
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Affiliation(s)
- Hannah Pearl
- College of Arts and Sciences, Tufts University, Medford, Massachusetts, USA
| | - Candace C Fleischer
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA.,Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, USA
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7
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Puris E, Saveleva L, de Sousa Maciel I, Kanninen KM, Auriola S, Fricker G. Protein Expression of Amino Acid Transporters Is Altered in Isolated Cerebral Microvessels of 5xFAD Mouse Model of Alzheimer's Disease. Mol Neurobiol 2023; 60:732-748. [PMID: 36367657 PMCID: PMC9849299 DOI: 10.1007/s12035-022-03111-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 10/26/2022] [Indexed: 11/13/2022]
Abstract
Membrane transporters such as ATP-binding cassette (ABC) and solute carrier (SLC) transporters expressed at the neurovascular unit (NVU) play an important role in drug delivery to the brain and have been demonstrated to be involved in Alzheimer's disease (AD) pathogenesis. However, our knowledge of quantitative changes in transporter absolute protein expression and functionality in vivo in NVU in AD patients and animal models is limited. The study aim was to investigate alterations in protein expression of ABC and SLC transporters in the isolated brain microvessels and brain prefrontal cortices of a widely used model of familial AD, 5xFAD mice (8 months old), using a sensitive liquid chromatography tandem mass spectrometry-based quantitative targeted absolute proteomic approach. Moreover, we examined alterations in brain prefrontal cortical and plasmatic levels of transporter substrates in 5xFAD mice compared to age-matched wild-type (WT) controls. ASCT1 (encoded by Slc1a4) protein expression in the isolated brain microvessels and brain prefrontal cortices of 5xFAD mice was twice higher compared to WT controls (p = 0.01). Brain cortical levels of ASCT1 substrate, serine, were increased in 5xFAD mice compared to WT animals. LAT1 (encoded by Slc7a5) and 4F2hc (encoded by Slc3a2) protein expressions were significantly altered in the isolated brain microvessels of 5xFAD mice compared to WT controls (p = 0.008 and p = 0.05, respectively). Overall, the study provides important information, which is crucial for the optimal use of the 5xFAD mouse model in AD drug development and for investigating novel drug delivery approaches. In addition, the findings of the study shed light on the novel potential mechanisms underlying AD pathogenesis.
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Affiliation(s)
- Elena Puris
- Institute of Pharmacy and Molecular Biotechnology, Ruprecht-Karls-University, Im Neuenheimer Feld 329, 69120 Heidelberg, Germany
| | - Liudmila Saveleva
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
| | - Izaque de Sousa Maciel
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
| | - Katja M. Kanninen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
| | - Seppo Auriola
- School of Pharmacy, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
| | - Gert Fricker
- Institute of Pharmacy and Molecular Biotechnology, Ruprecht-Karls-University, Im Neuenheimer Feld 329, 69120 Heidelberg, Germany
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Consumption and Metabolism of Extracellular Pyruvate by Cultured Rat Brain Astrocytes. Neurochem Res 2022; 48:1438-1454. [PMID: 36495387 PMCID: PMC10066139 DOI: 10.1007/s11064-022-03831-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 11/14/2022] [Accepted: 11/17/2022] [Indexed: 12/14/2022]
Abstract
AbstractBrain astrocytes are considered as glycolytic cell type, but these cells also produce ATP via mitochondrial oxidative phosphorylation. Exposure of cultured primary astrocytes in a glucose-free medium to extracellular substrates that are known to be metabolised by mitochondrial pathways, including pyruvate, lactate, beta-hydroxybutyrate, alanine and acetate, revealed that among the substrates investigated extracellular pyruvate was most efficiently consumed by astrocytes. Extracellular pyruvate was consumed by the cells almost proportional to time over hours in a concentration-dependent manner with apparent Michaelis–Menten kinetics [Km = 0.6 ± 0.1 mM, Vmax = 5.1 ± 0.8 nmol/(min × mg protein)]. The astrocytic consumption of pyruvate was strongly impaired in the presence of the monocarboxylate transporter 1 (MCT1) inhibitor AR-C155858 or by application of a 10-times excess of the MCT1 substrates lactate or beta-hydroxybutyrate. Pyruvate consumption by viable astrocytes was inhibited in the presence of UK5099, an inhibitor of the mitochondrial pyruvate carrier, or after application of the respiratory chain inhibitor antimycin A. In contrast, the mitochondrial uncoupler BAM15 strongly accelerated cellular pyruvate consumption. Lactate and alanine accounted after 3 h of incubation with pyruvate for around 60% and 10%, respectively, of the pyruvate consumed by the cells. These results demonstrate that consumption of extracellular pyruvate by astrocytes involves uptake via MCT1 and that the velocity of pyruvate consumption is strongly modified by substances that affect the entry of pyruvate into mitochondria or the activity of mitochondrial respiration.
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Impact of Inhibition of Glutamine and Alanine Transport on Cerebellar Glial and Neuronal Metabolism. Biomolecules 2022; 12:biom12091189. [PMID: 36139028 PMCID: PMC9496060 DOI: 10.3390/biom12091189] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 08/21/2022] [Accepted: 08/24/2022] [Indexed: 11/16/2022] Open
Abstract
The cerebellum, or “little brain”, is often overlooked in studies of brain metabolism in favour of the cortex. Despite this, anomalies in cerebellar amino acid homeostasis in a range of disorders have been reported. Amino acid homeostasis is central to metabolism, providing recycling of carbon backbones and ammonia between cell types. Here, we examined the role of cerebellar amino acid transporters in the cycling of glutamine and alanine in guinea pig cerebellar slices by inhibiting amino acid transporters and examining the resultant metabolism of [1-13C]d-glucose and [1,2-13C]acetate by NMR spectroscopy and LCMS. While the lack of specific inhibitors of each transporter makes interpretation difficult, by viewing results from experiments with multiple inhibitors we can draw inferences about the major cell types and transporters involved. In cerebellum, glutamine and alanine transfer is dominated by system A, blockade of which has maximum effect on metabolism, with contributions from System N. Inhibition of neural system A isoform SNAT1 by MeAIB resulted in greatly decreased metabolite pools and reduced net fluxes but showed little effect on fluxes from [1,2-13C]acetate unlike inhibition of SNAT3 and other glutamine transporters by histidine where net fluxes from [1,2-13C]acetate are reduced by ~50%. We interpret the data as further evidence of not one but several glutamate/glutamine exchange pools. The impact of amino acid transport inhibition demonstrates that the cerebellum has tightly coupled cells and that glutamate/glutamine, as well as alanine cycling, play a major role in that part of the brain.
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10
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Ahmadpour N, Kantroo M, Stobart JL. Extracellular Calcium Influx Pathways in Astrocyte Calcium Microdomain Physiology. Biomolecules 2021; 11:1467. [PMID: 34680100 PMCID: PMC8533159 DOI: 10.3390/biom11101467] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/25/2021] [Accepted: 10/01/2021] [Indexed: 02/08/2023] Open
Abstract
Astrocytes are complex glial cells that play many essential roles in the brain, including the fine-tuning of synaptic activity and blood flow. These roles are linked to fluctuations in intracellular Ca2+ within astrocytes. Recent advances in imaging techniques have identified localized Ca2+ transients within the fine processes of the astrocytic structure, which we term microdomain Ca2+ events. These Ca2+ transients are very diverse and occur under different conditions, including in the presence or absence of surrounding circuit activity. This complexity suggests that different signalling mechanisms mediate microdomain events which may then encode specific astrocyte functions from the modulation of synapses up to brain circuits and behaviour. Several recent studies have shown that a subset of astrocyte microdomain Ca2+ events occur rapidly following local neuronal circuit activity. In this review, we consider the physiological relevance of microdomain astrocyte Ca2+ signalling within brain circuits and outline possible pathways of extracellular Ca2+ influx through ionotropic receptors and other Ca2+ ion channels, which may contribute to astrocyte microdomain events with potentially fast dynamics.
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Affiliation(s)
| | | | - Jillian L. Stobart
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, 750 McDermot Avenue, Winnipeg, MG R3E 0T5, Canada; (N.A.); (M.K.)
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11
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Percival BC, Latour YL, Tifft CJ, Grootveld M. Rapid Identification of New Biomarkers for the Classification of GM1 Type 2 Gangliosidosis Using an Unbiased 1H NMR-Linked Metabolomics Strategy. Cells 2021; 10:572. [PMID: 33807817 PMCID: PMC7998791 DOI: 10.3390/cells10030572] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 02/16/2021] [Accepted: 02/17/2021] [Indexed: 01/04/2023] Open
Abstract
Biomarkers currently available for the diagnosis, prognosis, and therapeutic monitoring of GM1 gangliosidosis type 2 (GM1T2) disease are mainly limited to those discovered in targeted proteomic-based studies. In order to identify and establish new, predominantly low-molecular-mass biomarkers for this disorder, we employed an untargeted, multi-analyte approach involving high-resolution 1H NMR analysis coupled to a range of multivariate analysis and computational intelligence technique (CIT) strategies to explore biomolecular distinctions between blood plasma samples collected from GM1T2 and healthy control (HC) participants (n = 10 and 28, respectively). The relationship of these differences to metabolic mechanisms underlying the pathogenesis of GM1T2 disorder was also investigated. 1H NMR-linked metabolomics analyses revealed significant GM1T2-mediated dysregulations in ≥13 blood plasma metabolites (corrected p < 0.04), and these included significant upregulations in 7 amino acids, and downregulations in lipoprotein-associated triacylglycerols and alanine. Indeed, results acquired demonstrated a profound distinctiveness between the GM1T2 and HC profiles. Additionally, employment of a genome-scale network model of human metabolism provided evidence that perturbations to propanoate, ethanol, amino-sugar, aspartate, seleno-amino acid, glutathione and alanine metabolism, fatty acid biosynthesis, and most especially branched-chain amino acid degradation (p = 10-12-10-5) were the most important topologically-highlighted dysregulated pathways contributing towards GM1T2 disease pathology. Quantitative metabolite set enrichment analysis revealed that pathological locations associated with these dysfunctions were in the order fibroblasts > Golgi apparatus > mitochondria > spleen ≈ skeletal muscle ≈ muscle in general. In conclusion, results acquired demonstrated marked metabolic imbalances and alterations to energy demand, which are consistent with GM1T2 disease pathogenesis mechanisms.
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Affiliation(s)
- Benita C. Percival
- Leicester School of Pharmacy, De Montfort University, The Gateway, Leicester LE1 9BH, UK;
| | - Yvonne L. Latour
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN 37232-0252, USA;
| | - Cynthia J. Tifft
- Deputy Clinical Director, National Human Genome Research Institute, Director, National Institutes of Health, Bethesda, MD 20892-1205, USA;
| | - Martin Grootveld
- Leicester School of Pharmacy, De Montfort University, The Gateway, Leicester LE1 9BH, UK;
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12
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Saikia J, Borah B, Devi TG. Study of interacting mechanism of amino acid and Alzheimer's drug using vibrational techniques and computational method. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2020.129664] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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13
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Viswanath P, Batsios G, Mukherjee J, Gillespie AM, Larson PEZ, Luchman HA, Phillips JJ, Costello JF, Pieper RO, Ronen SM. Non-invasive assessment of telomere maintenance mechanisms in brain tumors. Nat Commun 2021; 12:92. [PMID: 33397920 PMCID: PMC7782549 DOI: 10.1038/s41467-020-20312-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 11/27/2020] [Indexed: 01/29/2023] Open
Abstract
Telomere maintenance is a universal hallmark of cancer. Most tumors including low-grade oligodendrogliomas use telomerase reverse transcriptase (TERT) expression for telomere maintenance while astrocytomas use the alternative lengthening of telomeres (ALT) pathway. Although TERT and ALT are hallmarks of tumor proliferation and attractive therapeutic targets, translational methods of imaging TERT and ALT are lacking. Here we show that TERT and ALT are associated with unique 1H-magnetic resonance spectroscopy (MRS)-detectable metabolic signatures in genetically-engineered and patient-derived glioma models and patient biopsies. Importantly, we have leveraged this information to mechanistically validate hyperpolarized [1-13C]-alanine flux to pyruvate as an imaging biomarker of ALT status and hyperpolarized [1-13C]-alanine flux to lactate as an imaging biomarker of TERT status in low-grade gliomas. Collectively, we have identified metabolic biomarkers of TERT and ALT status that provide a way of integrating critical oncogenic information into non-invasive imaging modalities that can improve tumor diagnosis and treatment response monitoring.
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Affiliation(s)
- Pavithra Viswanath
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA.
| | - Georgios Batsios
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
| | - Joydeep Mukherjee
- Department of Neurological Surgery, Helen Diller Research Center, University of California San Francisco, San Francisco, CA, USA
| | - Anne Marie Gillespie
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
| | - Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
| | - H Artee Luchman
- Department of Cell Biology and Anatomy, Arnie Charbonneau Cancer Institute and Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Joanna J Phillips
- Department of Neurological Surgery, Helen Diller Research Center, University of California San Francisco, San Francisco, CA, USA
| | - Joseph F Costello
- Department of Neurological Surgery, Helen Diller Research Center, University of California San Francisco, San Francisco, CA, USA
| | - Russell O Pieper
- Department of Neurological Surgery, Helen Diller Research Center, University of California San Francisco, San Francisco, CA, USA
| | - Sabrina M Ronen
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA.
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14
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Rahaman KA, Hasan M, Seo JE, Muresan AR, Song HJ, Min H, Son J, Lee J, Lee J, Kim B, Kwon OS. Severity of the autoimmune encephalomyelitis symptoms in mouse model by inhibition of LAT-1 transporters. JOURNAL OF PHARMACEUTICAL INVESTIGATION 2019. [DOI: 10.1007/s40005-019-00468-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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15
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Teav T, Gallart-Ayala H, van der Velpen V, Mehl F, Henry H, Ivanisevic J. Merged Targeted Quantification and Untargeted Profiling for Comprehensive Assessment of Acylcarnitine and Amino Acid Metabolism. Anal Chem 2019; 91:11757-11769. [DOI: 10.1021/acs.analchem.9b02373] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Tony Teav
- Metabolomics Platform, Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland
| | - Héctor Gallart-Ayala
- Metabolomics Platform, Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland
| | - Vera van der Velpen
- Metabolomics Platform, Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland
| | - Florence Mehl
- Metabolomics Platform, Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland
- Vital-IT−Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Hugues Henry
- Innovation and Development Laboratory, Clinical Chemistry Service, Lausanne University Hospital, 1011 Lausanne, Switzerland
| | - Julijana Ivanisevic
- Metabolomics Platform, Faculty of Biology and Medicine, University of Lausanne, 1005 Lausanne, Switzerland
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16
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Gupta S, Upadhayay D, Sharma U, Jagannathan NR, Gupta YK. Citalopram attenuated neurobehavioral, biochemical, and metabolic alterations in transient middle cerebral artery occlusion model of stroke in male Wistar rats. J Neurosci Res 2018; 96:1277-1293. [PMID: 29656429 DOI: 10.1002/jnr.24226] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 12/15/2017] [Accepted: 01/30/2018] [Indexed: 11/08/2022]
Abstract
Oxidative stress and inflammation are implicated as cardinal mechanisms of neuronal death following stroke. In the present study citalopram (Cit) was investigated in a 2 h middle cerebral artery occlusion (MCAo) model of stroke in male Wistar rats. Pretreatment, posttreatment (Post Cit) and pre plus posttreatment (Pre + Post Cit) with Cit were evaluated for its neuroprotective effect. In pretreatment protocol, effect of Cit at three doses (2, 4, and 8 mg/kg) administered i.p., 1 h prior to MCAo was evaluated using neurological deficit score (NDS), motor deficit paradigms, and cerebral infarction 24 h post-MCAo. In posttreatment and pre plus posttreatment protocol, the effective dose of Cit (4 mg/kg) was administered i.p., 0.5 h post-reperfusion (Post Cit) only, and 1 h prior to MCAo and again at 0.5 h post-reperfusion (Pre + Post Cit), respectively. These two groups were assessed for NDS and cerebral infarction. Though NDS was significantly reduced in both Post Cit and Pre + Post Cit groups, significant reduction in cerebral infarction was evident only in Pre + Post Cit group. Infarct volume assessed by magnetic resonance imaging was significantly attenuated in Pre + Post Cit group (10.6 ± 1.1%) compared to MCAo control group (18.5 ± 3.0%). Further, Pre + Post Cit treatment significantly altered 17 metabolites along with attenuation of malondialdehyde, reduced glutathione, matrix metalloproteinases, and apoptotic markers as compared to MCAo control. These results support the neuroprotective effect of Cit, mediated through amelioration of oxidative stress, inflammation, apoptosis, and altered metabolic profile.
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Affiliation(s)
- Sangeetha Gupta
- Department of Pharmacology, All India Institute of Medical Sciences, New Delhi-110029, India
| | - Deepti Upadhayay
- Department of NMR & MRI Facility, All India Institute of Medical Sciences, New Delhi-110029, India
| | - Uma Sharma
- Department of NMR & MRI Facility, All India Institute of Medical Sciences, New Delhi-110029, India
| | | | - Yogendra Kumar Gupta
- Department of Pharmacology, All India Institute of Medical Sciences, New Delhi-110029, India
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17
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Roy U, Conklin L, Schiller J, Matysik J, Berry JP, Alia A. Metabolic profiling of zebrafish (Danio rerio) embryos by NMR spectroscopy reveals multifaceted toxicity of β-methylamino-L-alanine (BMAA). Sci Rep 2017; 7:17305. [PMID: 29230019 PMCID: PMC5725574 DOI: 10.1038/s41598-017-17409-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/21/2017] [Indexed: 11/09/2022] Open
Abstract
β-methylamino-L-alanine (BMAA) has been linked to several interrelated neurodegenerative diseases. Despite considerable research, specific contributions of BMAA toxicity to neurodegenerative diseases remain to be fully resolved. In the present study, we utilized state-of-the-art high-resolution magic-angle spinning nuclear magnetic resonance (HRMAS NMR), applied to intact zebrafish (Danio rerio) embryos, as a model of vertebrate development, to elucidate changes in metabolic profiles associated with BMAA exposure. Complemented by several alternative analytical approaches (i.e., in vivo visualization and in vitro assay), HRMAS NMR identified robust and dose-dependent effect of BMAA on several relevant metabolic pathways suggesting a multifaceted toxicity of BMAA including: (1) localized production of reactive oxygen species (ROS), in the developing brain, consistent with excitotoxicity; (2) decreased protective capacity against excitotoxicity and oxidative stress including reduced taurine and glutathione; (3) inhibition of several developmentally stereotypical energetic and metabolic transitions, i.e., metabolic reprogramming; and (4) inhibition of lipid biosynthetic pathways. Matrix-assisted laser desorption time-of-flight (MALDI-ToF) mass spectrometry further identified specific effects on phospholipids linked to both neural development and neurodegeneration. Taken together, a unified model of the neurodevelopmental toxicity of BMAA in the zebrafish embryo is presented in relation to the potential contribution of BMAA to neurodegenerative disease.
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Affiliation(s)
- Upasana Roy
- Institute for Medical Physics and Biophysics, University of Leipzig, D-04107, Leipzig, Germany.,Institute of Analytical Chemistry, University of Leipzig, D-04103, Leipzig, Germany
| | - Laura Conklin
- Department of Chemistry and Biochemistry, Florida International University, North Miami, FL, 33181, USA
| | - Jürgen Schiller
- Institute for Medical Physics and Biophysics, University of Leipzig, D-04107, Leipzig, Germany
| | - Jörg Matysik
- Institute of Analytical Chemistry, University of Leipzig, D-04103, Leipzig, Germany
| | - John P Berry
- Department of Chemistry and Biochemistry, Florida International University, North Miami, FL, 33181, USA.
| | - A Alia
- Institute for Medical Physics and Biophysics, University of Leipzig, D-04107, Leipzig, Germany. .,Leiden Institute of Chemistry, 2333, Leiden, The Netherlands.
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18
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Comasco E, Vumma R, Toffoletto S, Johansson J, Flyckt L, Lewander T, Oreland L, Bjerkenstedt L, Andreou D, Söderman E, Terenius L, Agartz I, Jönsson EG, Venizelos N. Genetic and Functional Study of L-Type Amino Acid Transporter 1 in Schizophrenia. Neuropsychobiology 2017; 74:96-103. [PMID: 28190014 DOI: 10.1159/000455234] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Accepted: 12/20/2016] [Indexed: 12/27/2022]
Abstract
Schizophrenia involves neural catecholaminergic dysregulation. Tyrosine is the precursor of catecholamines, and its major transporter, according to studies on fibroblasts, in the brain is the L-type amino acid transporter 1 (LAT1). The present study assessed haplotype tag single-nucleotide polymorphisms (SNPs) of the SLC7A5/LAT1 gene in 315 patients with psychosis within the schizophrenia spectrum and 233 healthy controls to investigate genetic vulnerability to the disorder as well as genetic relationships to homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG), the major catecholamine metabolites in the cerebrospinal fluid (CSF). Moreover, the involvement of the different isoforms of the system L in tyrosine uptake and LAT1 tyrosine kinetics were studied in fibroblast cell lines of 10 patients with schizophrenia and 10 healthy controls. The results provide suggestive evidence of individual vulnerability to schizophrenia related to the LAT1 SNP rs9936204 genotype. A number of SNPs were nominally associated with CSF HVA and MHPG concentrations but did not survive correction for multiple testing. The LAT1 isoform was confirmed as the major tyrosine transporter in patients with schizophrenia. However, the kinetic parameters (maximal transport capacity, affinity of the binding sites, and diffusion constant of tyrosine transport through the LAT1 isoform) did not differ between patients with schizophrenia and controls. The present genetic findings call for independent replication in larger samples, while the functional study seems to exclude a role of LAT1 in the aberrant transport of tyrosine in fibroblasts of patients with schizophrenia.
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Affiliation(s)
- Erika Comasco
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
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19
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Achanta LB, Rowlands BD, Thomas DS, Housley GD, Rae CD. β-Hydroxybutyrate Boosts Mitochondrial and Neuronal Metabolism but is not Preferred Over Glucose Under Activated Conditions. Neurochem Res 2017; 42:1710-1723. [DOI: 10.1007/s11064-017-2228-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/06/2017] [Accepted: 03/09/2017] [Indexed: 12/21/2022]
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20
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Rowlands BD, Klugmann M, Rae CD. Acetate metabolism does not reflect astrocytic activity, contributes directly to GABA synthesis, and is increased by silent information regulator 1 activation. J Neurochem 2017; 140:903-918. [PMID: 27925207 DOI: 10.1111/jnc.13916] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 11/22/2016] [Accepted: 11/22/2016] [Indexed: 12/26/2022]
Abstract
[13 C]Acetate is known to label metabolites preferentially in astrocytes rather than neurons and it has consequently been used as a marker for astrocytic activity. Recent discoveries suggest that control of acetate metabolism and its contributions to the synthesis of metabolites in brain is not as simple as first thought. Here, using a Guinea pig brain cortical tissue slice model metabolizing [1-13 C]D-glucose and [1,2-13 C]acetate, we investigated control of acetate metabolism and the degree to which it reflects astrocytic activity. Using a range of [1,2-13 C]acetate concentrations, we found that acetate is a poor substrate for metabolism and will inhibit metabolism of itself and of glucose at concentrations in excess of 2 mmol/L. By activating astrocytes using potassium depolarization, we found that use of [1,2-13 C]acetate to synthesize glutamine decreases significantly under these conditions showing that acetate metabolism does not necessarily reflect astrocytic activity. By blocking synthesis of glutamine using methionine sulfoximine, we found that significant amount of [1,2-13 C]acetate are still incorporated into GABA and its metabolic precursors in neurons, with around 30% of the GABA synthesized from [1,2-13 C]acetate likely to be made directly in neurons rather than from glutamine supplied by astrocytes. Finally, to test whether activity of the acetate metabolizing enzyme acetyl-CoA synthetase is under acetylation control in the brain, we incubated slices with the AceCS1 deacetylase silent information regulator 1 (SIRT1) activator SRT 1720 and showed consequential increased incorporation of [1,2-13 C]acetate into metabolites. Taken together, these data show that acetate metabolism is not directly nor exclusively related to astrocytic metabolic activity, that use of acetate is related to enzyme acetylation and that acetate is directly metabolized to a significant degree in GABAergic neurons. Changes in acetate metabolism should be interpreted as modulation of metabolism through changes in cellular energetic status via altered enzyme acetylation levels rather than simply as an adjustment of glial-neuronal metabolic activity.
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Affiliation(s)
- Benjamin D Rowlands
- Neuroscience Research Australia, Randwick, NSW, Australia.,Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Matthias Klugmann
- Neuroscience Research Australia, Randwick, NSW, Australia.,Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Randwick, NSW, Australia.,School of Medical Sciences, The University of New South Wales, Sydney, NSW, Australia
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21
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Abstract
Glycine, besides exerting essential metabolic functions, is an important inhibitory neurotransmitter in caudal areas of the central nervous system and also a positive neuromodulator at excitatory glutamate-mediated synapses. Glial cells provide metabolic support to neurons and modulate synaptic activity. Six transporters belonging to three solute carrier families (SLC6, SLC38, and SLC7) are capable of transporting glycine across the glial plasma membrane. The unique glial glycine-selective transporter GlyT1 (SLC6) is the main regulator of synaptic glycine concentrations, assisted by the neuronal GlyT2. The five additional glycine transporters ATB0,+, SNAT1, SNAT2, SNAT5, and LAT2 display broad amino acid specificity and have differential contributions to glial glycine transport. Glial glycine transporters are divergent in sequence but share a similar architecture displaying the 5 + 5 inverted fold originally characterized in the leucine transporter LeuT. The availability of protein crystals solved at high resolution for prokaryotic and, more recently, eukaryotic homologues of this superfamily has advanced significantly our understanding of the mechanism of glycine transport.
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22
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Rae C, Nasrallah FA, Balcar VJ, Rowlands BD, Johnston GAR, Hanrahan JR. Metabolomic Approaches to Defining the Role(s) of GABAρ Receptors in the Brain. J Neuroimmune Pharmacol 2015; 10:445-56. [PMID: 25577264 DOI: 10.1007/s11481-014-9579-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Accepted: 12/26/2014] [Indexed: 10/24/2022]
Abstract
The inhibitory neurotransmitter γ-aminobutyric acid (GABA) acts through various types of receptors in the central nervous system. GABAρ receptors, defined by their characteristic pharmacology and presence of ρ subunits in the channel structure, are poorly understood and their role in the cortex is ill-defined. Here, we used a targeted pharmacological, NMR-based functional metabolomic approach in Guinea pig brain cortical tissue slices to identify a distinct role for these receptors. We compared metabolic fingerprints generated by a range of ligands active at GABAρ and included these in a principal components analysis with a library of other metabolic fingerprints obtained using ligands active at GABAA and GABAB, with inhibitors of GABA uptake and with compounds acting to inhibit enzymes active in the GABAergic system. This enabled us to generate a metabolic "footprint" of the GABAergic system which revealed classes of metabolic activity associated with GABAρ which are distinct from other GABA receptors. Antagonised GABAρ produce large metabolic effects at extrasynaptic sites suggesting they may be involved in tonic inhibition.
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Affiliation(s)
- Caroline Rae
- Neuroscience Research Australia, Barker St, Randwick, NSW, 2031, Australia,
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23
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Blecharz-Klin K, Joniec-Maciejak I, Jawna K, Pyrzanowska J, Piechal A, Wawer A, Widy-Tyszkiewicz E. Developmental exposure to paracetamol causes biochemical alterations in medulla oblongata. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2015; 40:369-374. [PMID: 26233562 DOI: 10.1016/j.etap.2015.07.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 07/02/2015] [Accepted: 07/03/2015] [Indexed: 06/04/2023]
Abstract
The effect and safety of prenatal and early life administration of paracetamol - routinely used over-the-counter antipyretic and analgesic medication on monoamines content and balance of amino acids in the medulla oblongata is still unknown. In this study we have determined the level of neurotransmitters in this structure in two-month old Wistar male rats exposed to paracetamol in the dose of 5 (P5, n=10) or 15mg/kg b.w. (P15, n=10) during prenatal period, lactation and till the end of the second month of life. Control group received drinking water (Con, n=10). Monoamines, their metabolites and amino acids concentration in medulla oblongata of rats were determined using high performance liquid chromatography (HPLC) in 60 postnatal day (PND60). This experiment shows that prenatal and early life paracetamol exposure modulates neurotransmission associated with serotonergic, noradrenergic and dopaminergic system in medulla oblongata. Reduction of alanine and taurine levels has also been established.
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Affiliation(s)
- Kamilla Blecharz-Klin
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Centre for Preclinical Research and Technology CePT, Banacha 1B, 02-097 Warsaw, Poland
| | - Ilona Joniec-Maciejak
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Centre for Preclinical Research and Technology CePT, Banacha 1B, 02-097 Warsaw, Poland
| | - Katarzyna Jawna
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Centre for Preclinical Research and Technology CePT, Banacha 1B, 02-097 Warsaw, Poland
| | - Justyna Pyrzanowska
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Centre for Preclinical Research and Technology CePT, Banacha 1B, 02-097 Warsaw, Poland
| | - Agnieszka Piechal
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Centre for Preclinical Research and Technology CePT, Banacha 1B, 02-097 Warsaw, Poland
| | - Adriana Wawer
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Centre for Preclinical Research and Technology CePT, Banacha 1B, 02-097 Warsaw, Poland
| | - Ewa Widy-Tyszkiewicz
- Department of Experimental and Clinical Pharmacology, Medical University of Warsaw, Centre for Preclinical Research and Technology CePT, Banacha 1B, 02-097 Warsaw, Poland.
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24
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Chen X, Xie C, Sun L, Ding J, Cai H. Longitudinal Metabolomics Profiling of Parkinson's Disease-Related α-Synuclein A53T Transgenic Mice. PLoS One 2015; 10:e0136612. [PMID: 26317866 PMCID: PMC4552665 DOI: 10.1371/journal.pone.0136612] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 08/06/2015] [Indexed: 12/31/2022] Open
Abstract
Metabolic homeostasis is critical for all biological processes in the brain. The metabolites are considered the best indicators of cell states and their rapid fluxes are extremely sensitive to cellular changes. While there are a few studies on the metabolomics of Parkinson's disease, it lacks longitudinal studies of the brain metabolic pathways affected by aging and the disease. Using ultra-high performance liquid chromatography and tandem mass spectroscopy (UPLC/MS), we generated the metabolomics profiling data from the brains of young and aged male PD-related α-synuclein A53T transgenic mice as well as the age- and gender-matched non-transgenic (nTg) controls. Principal component and unsupervised hierarchical clustering analyses identified distinctive metabolites influenced by aging and the A53T mutation. The following metabolite set enrichment classification revealed the alanine metabolism, redox and acetyl-CoA biosynthesis pathways were substantially disturbed in the aged mouse brains regardless of the genotypes, suggesting that aging plays a more prominent role in the alterations of brain metabolism. Further examination showed that the interaction effect of aging and genotype only disturbed the guanosine levels. The young A53T mice exhibited lower levels of guanosine compared to the age-matched nTg controls. The guanosine levels remained constant between the young and aged nTg mice, whereas the aged A53T mice showed substantially increased guanosine levels compared to the young mutant ones. In light of the neuroprotective function of guanosine, our findings suggest that the increase of guanosine metabolism in aged A53T mice likely represents a protective mechanism against neurodegeneration, while monitoring guanosine levels could be applicable to the early diagnosis of the disease.
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Affiliation(s)
- Xi Chen
- Transgenics Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
| | - Chengsong Xie
- Transgenics Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
| | - Lixin Sun
- Transgenics Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
| | - Jinhui Ding
- Bioinformatics Core, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
| | - Huaibin Cai
- Transgenics Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, 20892, United States of America
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25
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Rowlands BD, Lau CL, Ryall JG, Thomas DS, Klugmann M, Beart PM, Rae CD. Silent information regulator 1 modulator resveratrol increases brain lactate production and inhibits mitochondrial metabolism, whereas SRT1720 increases oxidative metabolism. J Neurosci Res 2015; 93:1147-56. [PMID: 25677687 DOI: 10.1002/jnr.23570] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/16/2015] [Accepted: 01/16/2015] [Indexed: 12/26/2022]
Abstract
Silent information regulators (SIRTs) have been shown to deacetylate a range of metabolic enzymes, including those in glycolysis and the Krebs cycle, and thus alter their activity. SIRTs require NAD(+) for their activity, linking cellular energy status to enzyme activity. To examine the impact of SIRT1 modulation on oxidative metabolism, this study tests the effect of ligands that are either SIRT-activating compounds (resveratrol and SRT1720) or SIRT inhibitors (EX527) on the metabolism of (13)C-enriched substrates by guinea pig brain cortical tissue slices with (13)C and (1)H nuclear magnetic resonance spectroscopy. Resveratrol increased lactate labeling but decreased incorporation of (13)C into Krebs cycle intermediates, consistent with effects on AMPK and inhibition of the F0/F1-ATPase. By testing with resveratrol that was directly applied to astrocytes with a Seahorse analyzer, increased glycolytic shift and increased mitochondrial proton leak resulting from interactions of resveratrol with the mitochondrial electron transport chain were revealed. SRT1720, by contrast, stimulated incorporation of (13)C into Krebs cycle intermediates and reduced incorporation into lactate, although the inhibitor EX527 paradoxically also increased Krebs cycle (13)C incorporation. In summary, the various SIRT1 modulators show distinct acute effects on oxidative metabolism. The strong effects of resveratrol on the mitochondrial respiratory chain and on glycolysis suggest that caution should be used in attempts to increase bioavailability of this compound in the CNS.
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Affiliation(s)
- Benjamin D Rowlands
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,Department of Physiology and Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Randwick, New South Wales, Australia
| | - Chew Ling Lau
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - James G Ryall
- Stem Cell Metabolism and Regenerative Medicine Group, Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Donald S Thomas
- Mark Wainwright Analytical Centre, The University of New South Wales, Randwick, New South Wales, Australia
| | - Matthias Klugmann
- Department of Physiology and Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Randwick, New South Wales, Australia
| | - Philip M Beart
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,Department of Physiology and Translational Neuroscience Facility, School of Medical Sciences, The University of New South Wales, Randwick, New South Wales, Australia
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26
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Rae C, Balcar VJ. A Chip Off the Old Block: The Brain Slice as a Model for Metabolic Studies of Brain Compartmentation and Neuropharmacology. BRAIN ENERGY METABOLISM 2014. [DOI: 10.1007/978-1-4939-1059-5_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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27
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Roles of changes in active glutamine transport in brain edema development during hepatic encephalopathy: an emerging concept. Neurochem Res 2013; 39:599-604. [PMID: 24072671 PMCID: PMC3926979 DOI: 10.1007/s11064-013-1141-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/20/2013] [Accepted: 08/22/2013] [Indexed: 12/12/2022]
Abstract
Excessive glutamine (Gln) synthesis in ammonia-overloaded astrocytes contributes to astrocytic swelling and brain edema, the major complication of hepatic encephalopathy (HE). Much of the newly formed Gln is believed to enter mitochondria, where it is recycled to ammonia, which causes mitochondrial dysfunction (a “Trojan horse” mode of action). A portion of Gln may increase osmotic pressure in astrocytes and the interstitial space, directly and independently contributing to brain tissue swelling. Here we discuss the possibility that altered functioning of Gln transport proteins located in the cellular or mitochondrial membranes, modulates the effects of increased Gln synthesis. Accumulation of excess Gln in mitochondria involves a carrier-mediated transport which is activated by ammonia. Studies on the expression of the cell membrane N-system transporters SN1 (SNAT3) and SN2 (SNAT5), which mediate Gln efflux from astrocytes rendered HE model-dependent effects. HE lowered the expression of SN1 at the RNA and protein level in the cerebral cortex (cc) in the thioacetamide (TAA) model of HE and the effect paralleled induction of cerebral cortical edema. Neither SN1 nor SN2 expression was affected by simple hyperammonemia, which produces no cc edema. TAA-induced HE is also associated with decreased expression of mRNA coding for the system A carriers SAT1 and SAT2, which stimulate Gln influx to neurons. Taken together, changes in the expression of Gln transporters during HE appear to favor retention of Gln in astrocytes and/or the interstitial space of the brain. HE may also affect arginine (Arg)/Gln exchange across the astrocytic cell membrane due to changes in the expression of the hybrid Arg/Gln transporter y+LAT2. Gln export from brain across the blood–brain barrier may be stimulated by HE via its increased exchange with peripheral tryptophan.
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Metabolism, Compartmentation, Transport and Production of Acetate in the Cortical Brain Tissue Slice. Neurochem Res 2012; 37:2541-53. [DOI: 10.1007/s11064-012-0847-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 07/12/2012] [Accepted: 07/13/2012] [Indexed: 10/28/2022]
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Khunweeraphong N, Nagamori S, Wiriyasermkul P, Nishinaka Y, Wongthai P, Ohgaki R, Tanaka H, Tominaga H, Sakurai H, Kanai Y. Establishment of stable cell lines with high expression of heterodimers of human 4F2hc and human amino acid transporter LAT1 or LAT2 and delineation of their differential interaction with α-alkyl moieties. J Pharmacol Sci 2012; 119:368-80. [PMID: 22850614 PMCID: PMC7128428 DOI: 10.1254/jphs.12124fp] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
System L is a major transport system for cellular uptake of neutral amino acids. Among system L transporters, L-type amino acid transporter 1 (LAT1) is responsible for the nutrient uptake in cancer cells, whereas L-type amino acid transporter 2 (LAT2) is a transporter for non-cancer cells. In this study, we have established HEK293 cell lines stably expressing high levels of human LAT1 and LAT2 forming heterodimers with native human 4F2hc of the cells. We have found that l-[14C]alanine is an appropriate substrate to examine the function of LAT2, whereas l-[14C]leucine is used for LAT1. By using l-[14C]alanine on LAT2, we have for the first time directly evaluated the function of human LAT2 expressed in mammalian cells and obtained its reliable kinetics. Using α-alkyl amino acids including α-methyl-alanine and α-ethyl-l-alanine, we have demonstrated that α-alkyl groups interfere with the interaction with LAT2. These cell lines with higher practical advantages would be useful for screening and analyzing compounds to develop LAT1-specific drugs that can be used for cancer diagnosis and therapeutics. The strategy that we took to establish the cell lines would also be applicable to the other heterodimeric transporters with important therapeutic implications.
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Affiliation(s)
- Narakorn Khunweeraphong
- Division of Bio-system Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Japan
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Uwechue NM, Marx MC, Chevy Q, Billups B. Activation of glutamate transport evokes rapid glutamine release from perisynaptic astrocytes. J Physiol 2012; 590:2317-31. [PMID: 22411007 DOI: 10.1113/jphysiol.2011.226605] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Stimulation of astrocytes by neuronal activity and the subsequent release of neuromodulators is thought to be an important regulator of synaptic communication. In this study we show that astrocytes juxtaposed to the glutamatergic calyx of Held synapse in the rat medial nucleus of the trapezoid body (MNTB) are stimulated by the activation of glutamate transporters and consequently release glutamine on a very rapid timescale. MNTB principal neurones express electrogenic system A glutamine transporters, and were exploited as glutamine sensors in this study. By simultaneous whole-cell voltage clamping astrocytes and neighbouring MNTB neurones in brainstem slices, we show that application of the excitatory amino acid transporter (EAAT) substrate d-aspartate stimulates astrocytes to rapidly release glutamine, which is detected by nearby MNTB neurones. This release is significantly reduced by the toxins L-methionine sulfoximine and fluoroacetate, which reduce glutamine concentrations specifically in glial cells. Similarly, glutamine release was also inhibited by localised inactivation of EAATs in individual astrocytes, using internal DL-threo-β-benzyloxyaspartic acid (TBOA) or dissipating the driving force by modifying the patch-pipette solution. These results demonstrate that astrocytes adjacent to glutamatergic synapses can release glutamine in a temporally precise, controlled manner in response to glial glutamate transporter activation. Since glutamine can be used by neurones as a precursor for glutamate and GABA synthesis, this represents a potential feedback mechanism by which astrocytes can respond to synaptic activation and react in a way that sustains or enhances further communication. This would therefore represent an additional manifestation of the tripartite relationship between synapses and astrocytes.
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Affiliation(s)
- Nneka M Uwechue
- Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, UK
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31
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Aminoaciduria, but normal thyroid hormone levels and signalling, in mice lacking the amino acid and thyroid hormone transporter Slc7a8. Biochem J 2011; 439:249-55. [PMID: 21726201 DOI: 10.1042/bj20110759] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
LAT2 (system L amino acid transporter 2) is composed of the subunits Slc7a8/Lat2 and Slc3a2/4F2hc. This transporter is highly expressed along the basolateral membranes of absorptive epithelia in kidney and small intestine, but is also abundant in the brain. Lat2 is an energy-independent exchanger of neutral amino acids, and was shown to transport thyroid hormones. We report in the present paper that targeted inactivation of Slc7a8 leads to increased urinary loss of small neutral amino acids. Development and growth of Slc7a8(-/-) mice appears normal, suggesting functional compensation of neutral amino acid transport by alternative transporters in kidney, intestine and placenta. Movement co-ordination is slightly impaired in mutant mice, although cerebellar development and structure remained inconspicuous. Circulating thyroid hormones, thyrotropin and thyroid hormone-responsive genes remained unchanged in Slc7a8(-/-) mice, possibly because of functional compensation by the thyroid hormone transporter Mct8 (monocarboxylate transporter 8), which is co-expressed in many cell types. The reason for the mild neurological phenotype remains unresolved.
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32
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Lee DW, Kim SY, Lee T, Nam YK, Ju A, Woo DC, You SJ, Han JS, Lee SH, Choi CB, Kim SS, Shin HC, Kim HY, Kim DJ, Rhim HS, Choe BY. Ex vivo detection for chronic ethanol consumption-induced neurochemical changes in rats. Brain Res 2011; 1429:134-44. [PMID: 22079322 DOI: 10.1016/j.brainres.2011.10.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 09/16/2011] [Accepted: 10/09/2011] [Indexed: 12/29/2022]
Abstract
The aim of this study was to quantitatively investigate the chronic ethanol-induced cerebral metabolic changes in various regions of the rat brain, using the proton high resolution magic angle spinning spectroscopy technique. The rats were divided into two groups (control group: N=11, ethanol-treated group: N=11) and fed with the liquid diets for 10 weeks. In each week, the mean intake volumes of liquid diet were measured. The brain tissues, including cerebellum (Cere), frontal cortex (FC), hippocampus (Hip), occipital cortex (OC) and thalamus (Thal), were harvested immediately after the end of experiments. The ex vivo proton spectra for the five brain regions were acquired with the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence at 500-MHz NMR spectrometer. All of the spectra were processed using the LCModel software, with simulated basis-set file, and the metabolite levels were referenced to total creatine. In the ethanol liquid diet group, there were significant increases in the metabolites ratio levels, as compared to control (Cere: alanine, glutathione, and N-acetlyaspartate; FC: phosphocholine and taurine; Hip: alanine, glutamine, and N-acetylaspartate; OC: glutamine; Thal: alanine, γ-aminobutyric acid, glutamate, glycerophosphocholine, phosphocholine, taurine, and free choline). However, in the ethanol liquid diet group, the myo-inositol levels of the OC were significantly lower. The present study demonstrates how chronic ethanol consumption affects cerebral metabolites in the chronic ethanol-treated rat. Therefore, this result could be useful to pursue clinical applications for quantitative diagnosis in human alcoholism.
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Affiliation(s)
- Do-Wan Lee
- Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, South Korea
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Duarte JMN, Lanz B, Gruetter R. Compartmentalized Cerebral Metabolism of [1,6-(13)C]Glucose Determined by in vivo (13)C NMR Spectroscopy at 14.1 T. FRONTIERS IN NEUROENERGETICS 2011; 3:3. [PMID: 21713114 PMCID: PMC3112327 DOI: 10.3389/fnene.2011.00003] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 05/17/2011] [Indexed: 11/13/2022]
Abstract
Cerebral metabolism is compartmentalized between neurons and glia. Although glial glycolysis is thought to largely sustain the energetic requirements of neurotransmission while oxidative metabolism takes place mainly in neurons, this hypothesis is matter of debate. The compartmentalization of cerebral metabolic fluxes can be determined by (13)C nuclear magnetic resonance (NMR) spectroscopy upon infusion of (13)C-enriched compounds, especially glucose. Rats under light α-chloralose anesthesia were infused with [1,6-(13)C]glucose and (13)C enrichment in the brain metabolites was measured by (13)C NMR spectroscopy with high sensitivity and spectral resolution at 14.1 T. This allowed determining (13)C enrichment curves of amino acid carbons with high reproducibility and to reliably estimate cerebral metabolic fluxes (mean error of 8%). We further found that TCA cycle intermediates are not required for flux determination in mathematical models of brain metabolism. Neuronal tricarboxylic acid cycle rate (V(TCA)) and neurotransmission rate (V(NT)) were 0.45 ± 0.01 and 0.11 ± 0.01 μmol/g/min, respectively. Glial V(TCA) was found to be 38 ± 3% of total cerebral oxidative metabolism, accounting for more than half of neuronal oxidative metabolism. Furthermore, glial anaplerotic pyruvate carboxylation rate (V(PC)) was 0.069 ± 0.004 μmol/g/min, i.e., 25 ± 1% of the glial TCA cycle rate. These results support a role of glial cells as active partners of neurons during synaptic transmission beyond glycolytic metabolism.
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Affiliation(s)
- João M N Duarte
- Center for Biomedical Imaging, Ecole Polytechnique Fédérale de Lausanne Lausanne, Switzerland
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Nasrallah FA, Balcar VJ, Rae CD. Activity-dependent γ-aminobutyric acid release controls brain cortical tissue slice metabolism. J Neurosci Res 2011; 89:1935-45. [DOI: 10.1002/jnr.22649] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 02/15/2011] [Accepted: 03/01/2011] [Indexed: 12/16/2022]
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Pardo B, Rodrigues TB, Contreras L, Garzón M, Llorente-Folch I, Kobayashi K, Saheki T, Cerdan S, Satrústegui J. Brain glutamine synthesis requires neuronal-born aspartate as amino donor for glial glutamate formation. J Cereb Blood Flow Metab 2011; 31:90-101. [PMID: 20736955 PMCID: PMC3049464 DOI: 10.1038/jcbfm.2010.146] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The glutamate-glutamine cycle faces a drain of glutamate by oxidation, which is balanced by the anaplerotic synthesis of glutamate and glutamine in astrocytes. De novo synthesis of glutamate by astrocytes requires an amino group whose origin is unknown. The deficiency in Aralar/AGC1, the main mitochondrial carrier for aspartate-glutamate expressed in brain, results in a drastic fall in brain glutamine production but a modest decrease in brain glutamate levels, which is not due to decreases in neuronal or synaptosomal glutamate content. In vivo (13)C nuclear magnetic resonance labeling with (13)C(2)acetate or (1-(13)C) glucose showed that the drop in brain glutamine is due to a failure in glial glutamate synthesis. Aralar deficiency induces a decrease in aspartate content, an increase in lactate production, and lactate-to-pyruvate ratio in cultured neurons but not in cultured astrocytes, indicating that Aralar is only functional in neurons. We find that aspartate, but not other amino acids, increases glutamate synthesis in both control and aralar-deficient astrocytes, mainly by serving as amino donor. These findings suggest the existence of a neuron-to-astrocyte aspartate transcellular pathway required for astrocyte glutamate synthesis and subsequent glutamine formation. This pathway may provide a mechanism to transfer neuronal-born redox equivalents to mitochondria in astrocytes.
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Affiliation(s)
- Beatriz Pardo
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa UAM-CSIC, and CIBER de Enfermedades Raras, Universidad Autónoma de Madrid, Madrid, Spain
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36
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Braun D, Kinne A, Bräuer AU, Sapin R, Klein MO, Köhrle J, Wirth EK, Schweizer U. Developmental and cell type-specific expression of thyroid hormone transporters in the mouse brain and in primary brain cells. Glia 2010; 59:463-71. [DOI: 10.1002/glia.21116] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 11/08/2010] [Indexed: 11/08/2022]
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37
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He Y, Hakvoort TBM, Vermeulen JLM, Labruyère WT, De Waart DR, Van Der Hel WS, Ruijter JM, Uylings HBM, Lamers WH. Glutamine synthetase deficiency in murine astrocytes results in neonatal death. Glia 2010; 58:741-54. [PMID: 20140959 DOI: 10.1002/glia.20960] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Glutamine synthetase (GS) is a key enzyme in the "glutamine-glutamate cycle" between astrocytes and neurons, but its function in vivo was thus far tested only pharmacologically. Crossing GS(fl/lacZ) or GS(fl/fl) mice with hGFAP-Cre mice resulted in prenatal excision of the GS(fl) allele in astrocytes. "GS-KO/A" mice were born without malformations, did not suffer from seizures, had a suckling reflex, and did drink immediately after birth, but then gradually failed to feed and died on postnatal day 3. Artificial feeding relieved hypoglycemia and prolonged life, identifying starvation as the immediate cause of death. Neuronal morphology and brain energy levels did not differ from controls. Within control brains, amino acid concentrations varied in a coordinate way by postnatal day 2, implying an integrated metabolic network had developed. GS deficiency caused a 14-fold decline in cortical glutamine and a sevenfold decline in cortical alanine concentration, but the rising glutamate levels were unaffected and glycine was twofold increased. Only these amino acids were uncoupled from the metabolic network. Cortical ammonia levels increased only 1.6-fold, probably reflecting reduced glutaminolysis in neurons and detoxification of ammonia to glycine. These findings identify the dramatic decrease in (cortical) glutamine concentration as the primary cause of brain dysfunction in GS-KO/A mice. The temporal dissociation between GS(fl) elimination and death, and the reciprocal changes in the cortical concentration of glutamine and alanine in GS-deficient and control neonates indicate that the phenotype of GS deficiency in the brain emerges coincidentally with the neonatal activation of the glutamine-glutamate and the associated alanine-lactate cycles.
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Affiliation(s)
- Youji He
- AMC Liver Center and Department of Anatomy and Embryology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Changes in kinetics of amino acid uptake at the ageing ovine blood-cerebrospinal fluid barrier. Neurobiol Aging 2010; 33:121-33. [PMID: 20138405 DOI: 10.1016/j.neurobiolaging.2010.01.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 01/15/2010] [Accepted: 01/19/2010] [Indexed: 01/05/2023]
Abstract
Amino acids (AA) in brain are precisely controlled by blood-brain barriers, which undergo a host of changes in both morphology and function during ageing. The effect of these age-related changes on AA homeostasis in brain is not well described. This study investigated the kinetics of four AA (Leu, Phe, Ala and Lys) uptakes at young and old ovine choroid plexus (CP), the blood-cerebrospinal fluid (CSF) barrier (BCB), and measured AA concentrations in CSF and plasma samples. In old sheep, the weight of lateral CP increased, so did the ratio of CP/brain. The expansion of the CP is consistent with clinical observation of thicker leptomeninges in old age. AA concentrations in old CSF, plasma and their ratio were different from the young. Both V(max) and K(m) of Phe and Lys were significant higher compared to the young, indicating higher trans-stimulation in old BCB. Cross-competition and kinetic inhibition studies found the sensitivity and specificity of these transporters were impaired in old BCB. These changes may be the first signs of a compromised barrier system in ageing brain leading increased AA influx into the brain causing neurotoxicity.
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Rae C, Nasrallah FA, Bröer S. Metabolic effects of blocking lactate transport in brain cortical tissue slices using an inhibitor specific to MCT1 and MCT2. Neurochem Res 2009; 34:1783-91. [PMID: 19404741 DOI: 10.1007/s11064-009-9973-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 04/07/2009] [Indexed: 11/25/2022]
Abstract
A novel inhibitor of lactate transport, AR-C122982, was used to study the effect of inhibiting the monocarboxylate transporters MCT1 and MCT2 on cortical brain slice metabolism. We studied metabolism of L-[3-13C]lactate, and D-[1-13C]glucose under a range of conditions. Experiments using L-[3-13C]lactate showed that the inhibitor AR-C122982 altered exchange of lactate. Under depolarizing conditions, net flux of label from D-[1-13C]glucose was barely altered by 10 or 100 nM AR-C122982. In the presence of AMPA or glutamate there were increases in net flux of label and metabolic pool sizes. These data suggest lactate may supply compartments in the brain not usually directly accessed by glucose. In general, it would appear that movement of lactate between cell types is not essential for metabolic activity, with the heavy metabolic workloads imposed being unaffected by inhibition of MCT1 and MCT2. Further experiments investigating the mechanism of operation of AR-C122982 are necessary to corroborate this finding.
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Affiliation(s)
- Caroline Rae
- Prince of Wales Medical Research Institute, Barker St., Randwick, NSW 2031, Australia.
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Hilgier W, Freśko I, Klemenska E, Beresewicz A, Oja SS, Saransaari P, Albrecht J, Zielińska M. Glutamine inhibits ammonia-induced accumulation of cGMP in rat striatum limiting arginine supply for NO synthesis. Neurobiol Dis 2009; 35:75-81. [PMID: 19379813 DOI: 10.1016/j.nbd.2009.04.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 04/08/2009] [Accepted: 04/11/2009] [Indexed: 10/20/2022] Open
Abstract
Brain L-glutamine (Gln) accumulation and increased activity of the NO/cGMP pathway are immediate consequences of acute exposure to ammonia. This study tested whether excess Gln may influence NO and/or cGMP synthesis. Intrastriatal administration of the glutaminase inhibitor 6-diazo-5-oxo-L-norleucine or the system A-specific Gln uptake inhibitor methylaminoisobutyrate increased microdialysate Gln concentration and reduced basal and ammonia-induced NO and cGMP accumulation. Gln applied in vivo (via microdialysis) or in vitro (to rat brain cortical slices) reduced NO and cGMP accumulation in the presence and/or absence of ammonia, but not cGMP synthesis induced by the NO donor sodium nitroprusside. Attenuation of cGMP synthesis by Gln was prevented by administration of L-arginine (Arg). The L-arginine co-substrates of y(+)LAT2 transport system, L-leucine and cyclo-leucine, mimicked the effect of exogenous Gln, suggesting that Gln limits Arg supply for NO synthesis by interfering with y+LAT2-mediated Arg uptake across the cell membrane.
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Affiliation(s)
- Wojciech Hilgier
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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Nasrallah FA, Griffin JL, Balcar VJ, Rae C. Understanding your inhibitions: effects of GABA and GABAAreceptor modulation on brain cortical metabolism. J Neurochem 2009; 108:57-71. [DOI: 10.1111/j.1471-4159.2008.05742.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Vumma R, Wiesel FA, Flyckt L, Bjerkenstedt L, Venizelos N. Functional characterization of tyrosine transport in fibroblast cells from healthy controls. Neurosci Lett 2008; 434:56-60. [PMID: 18262359 DOI: 10.1016/j.neulet.2008.01.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Revised: 12/20/2007] [Accepted: 01/13/2008] [Indexed: 10/22/2022]
Abstract
Human fibroblast cells are an advantageous model to study the transport of amino acids across cell membranes, since one can control the environmental factors. A major problem in all earlier studies is the lack of precise and detailed knowledge regarding the expression and functionality of tyrosine transporters in human fibroblasts. This motivated us to perform a systematic functional characterization of the tyrosine transport in fibroblast cells with respect to the isoforms of system-L (LAT1, LAT2, LAT3, LAT4), which is the major transporter of tyrosine. Ten (n=10) fibroblast cell lines from healthy volunteers were included in the study. Uptake of L-[U-14C] tyrosine in fibroblasts was measured using the cluster tray method in the presence and absence of excess concentrations of various combinations of inhibitors. This study demonstrated that LAT1 is involved in 90% of total uptake of tyrosine and also around 51% of alanine. Not more than 10% can be accounted for by LAT2, LAT3 and LAT4 isoforms. LAT2 seems to be functionally weak in uptake of tyrosine while LAT3 and LAT4 contributed around 7%. 10% could be contributed by system-A (ATA2 isoform). Alanine consequently inhibited the tyrosine transport by up to 60%. Tyrosine transport through the LAT1 isoform has a higher affinity compared to system-L. In conclusion, the LAT1 isoform is the major transporter of tyrosine in human fibroblast cells. Competition between tyrosine and alanine for transport is shown to exist, probably between LAT1 and LAT2 isoforms. This study established fibroblast cells as a suitable experimental model for studying amino acid transport defects in humans.
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Affiliation(s)
- Ravi Vumma
- Department of Clinical Medicine, Biomedicine, Orebro University, SE-701 82 Orebro, Sweden
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