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Grønbæk-Thygesen M, Hartmann-Petersen R. Cellular and molecular mechanisms of aspartoacylase and its role in Canavan disease. Cell Biosci 2024; 14:45. [PMID: 38582917 PMCID: PMC10998430 DOI: 10.1186/s13578-024-01224-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 03/24/2024] [Indexed: 04/08/2024] Open
Abstract
Canavan disease is an autosomal recessive and lethal neurological disorder, characterized by the spongy degeneration of the white matter in the brain. The disease is caused by a deficiency of the cytosolic aspartoacylase (ASPA) enzyme, which catalyzes the hydrolysis of N-acetyl-aspartate (NAA), an abundant brain metabolite, into aspartate and acetate. On the physiological level, the mechanism of pathogenicity remains somewhat obscure, with multiple, not mutually exclusive, suggested hypotheses. At the molecular level, recent studies have shown that most disease linked ASPA gene variants lead to a structural destabilization and subsequent proteasomal degradation of the ASPA protein variants, and accordingly Canavan disease should in general be considered a protein misfolding disorder. Here, we comprehensively summarize the molecular and cell biology of ASPA, with a particular focus on disease-linked gene variants and the pathophysiology of Canavan disease. We highlight the importance of high-throughput technologies and computational prediction tools for making genotype-phenotype predictions as we await the results of ongoing trials with gene therapy for Canavan disease.
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Affiliation(s)
- Martin Grønbæk-Thygesen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200N, Copenhagen, Denmark.
| | - Rasmus Hartmann-Petersen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200N, Copenhagen, Denmark.
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Becker I, Wang-Eckhardt L, Eckhardt M. NAAG synthetase deficiency has only low influence on pathogenesis in a Canavan disease mouse model. J Inherit Metab Dis 2024; 47:230-243. [PMID: 38011891 DOI: 10.1002/jimd.12693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 11/29/2023]
Abstract
Canavan disease (CD) is a leukodystrophy caused by mutations in the N-acetylaspartate (NAA) hydrolase aspartoacylase (ASPA). Inability to degrade NAA and its accumulation in the brain results in spongiform myelin degeneration. NAA is mainly synthesized by neurons, where it is also a precursor of the neuropeptide N-acetylaspartylglutamate (NAAG). Hydrolysis of this peptide by glutamate carboxypeptidases is an additional source of extracellular NAA besides the instant neuronal release of NAA. This study examines to what extent NAA released from NAAG contributes to NAA accumulation and pathogenesis in the brain of Aspanur7/nur7 mutant mice, an established model of CD. Towards this aim, Aspanur7/nur7 mice with additional deficiencies in NAAG synthetase genes Rimklb and/or Rimkla were generated. Loss of myelin in Aspanur7/nur7 mice was not significantly affected by Rimkla and Rimklb deficiency and there was also no obvious change in the extent of brain vacuolation. Astrogliosis was slightly reduced in the forebrain of Rimkla and Rimklb double deficient Aspanur7/nur7 mice. However, only minor improvements at the behavioral level were found. The brain NAA accumulation in CD mice was, however, not significantly reduced in the absence of NAAG synthesis. In summary, there was only a weak tendency towards reduced pathogenic symptoms in Aspanur7/nur7 mice deficient in NAAG synthesis. Therefore, we conclude that NAAG metabolism has little influence on NAA accumulation in Aspanur7/nur7 mice and development of pathological symptoms in CD.
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Affiliation(s)
- Ivonne Becker
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Lihua Wang-Eckhardt
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Matthias Eckhardt
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
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Revie L, Metzler-Baddeley C. Age-related fornix decline predicts conservative response strategy-based slowing in perceptual decision-making. AGING BRAIN 2024; 5:100106. [PMID: 38318456 PMCID: PMC10838937 DOI: 10.1016/j.nbas.2024.100106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 12/28/2023] [Accepted: 01/04/2024] [Indexed: 02/07/2024] Open
Abstract
Aging leads to response slowing but the underpinning cognitive and neural mechanisms remain elusive. We modelled older and younger adults' response times (RT) from a flanker task with a diffusion drift model (DDM) and employed diffusion-weighted magnetic resonance imaging and spectroscopy to study neurobiological predictors of DDM components (drift-rate, boundary separation, non-decision time). Microstructural indices were derived from white matter pathways involved in visuo-perceptual and attention processing [optic radiation, inferior and superior longitudinal fasciculi (ILF, SLF), fornix]. Estimates of metabolite concentrations [N-acetyl aspartate (NAA), glutamate (Glx), and γ-aminobutyric acid (GABA), creatine (Cr), choline (Cho), myoinositol (mI)] were measured from occipital (OCC), anterior cingulate (ACC) and posterior parietal cortices (PPC). Age-related increases in RT, boundary separation, and non-decision time were observed with response conservatism acounting for RT slowing. Aging was associated with reductions in white matter microstructure (lower fractional anisotropy and restricted signal fraction, larger diffusivities) and in metabolites (NAA in ACC and PPC, Glx in ACC). Regression analyses identified brain regions involved in top-down (fornix, SLF, ACC, PPC) and bottom-up (ILF, optic radiation OCC) processing as predictors for DDM parameters and RT. Fornix FA was the strongest predictor for increases in boundary separation (beta = -0.8) and mediated the effects of age on RT. These findings demonstrate that response slowing in visual discrimination is driven by the adoption of a more conservative response strategy. Age-related fornix decline may result in noisier communication of contextual information from the hippocampus to anterior decision-making regions and thus contribute to the conservative response strategy shift.
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Affiliation(s)
- Lauren Revie
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Maindy Road, Cardiff CF24 4HQ, United Kingdom
| | - Claudia Metzler-Baddeley
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Maindy Road, Cardiff CF24 4HQ, United Kingdom
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Reed AL, Mitchell W, Alexandrescu AT, Alder NN. Interactions of amyloidogenic proteins with mitochondrial protein import machinery in aging-related neurodegenerative diseases. Front Physiol 2023; 14:1263420. [PMID: 38028797 PMCID: PMC10652799 DOI: 10.3389/fphys.2023.1263420] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 10/02/2023] [Indexed: 12/01/2023] Open
Abstract
Most mitochondrial proteins are targeted to the organelle by N-terminal mitochondrial targeting sequences (MTSs, or "presequences") that are recognized by the import machinery and subsequently cleaved to yield the mature protein. MTSs do not have conserved amino acid compositions, but share common physicochemical properties, including the ability to form amphipathic α-helical structures enriched with basic and hydrophobic residues on alternating faces. The lack of strict sequence conservation implies that some polypeptides can be mistargeted to mitochondria, especially under cellular stress. The pathogenic accumulation of proteins within mitochondria is implicated in many aging-related neurodegenerative diseases, including Alzheimer's, Parkinson's, and Huntington's diseases. Mechanistically, these diseases may originate in part from mitochondrial interactions with amyloid-β precursor protein (APP) or its cleavage product amyloid-β (Aβ), α-synuclein (α-syn), and mutant forms of huntingtin (mHtt), respectively, that are mediated in part through their associations with the mitochondrial protein import machinery. Emerging evidence suggests that these amyloidogenic proteins may present cryptic targeting signals that act as MTS mimetics and can be recognized by mitochondrial import receptors and transported into different mitochondrial compartments. Accumulation of these mistargeted proteins could overwhelm the import machinery and its associated quality control mechanisms, thereby contributing to neurological disease progression. Alternatively, the uptake of amyloidogenic proteins into mitochondria may be part of a protein quality control mechanism for clearance of cytotoxic proteins. Here we review the pathomechanisms of these diseases as they relate to mitochondrial protein import and effects on mitochondrial function, what features of APP/Aβ, α-syn and mHtt make them suitable substrates for the import machinery, and how this information can be leveraged for the development of therapeutic interventions.
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Affiliation(s)
- Ashley L. Reed
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Wayne Mitchell
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - Andrei T. Alexandrescu
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Nathan N. Alder
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
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Bissonnette JN, Francis AM, MacNeil S, Crocker CE, Tibbo PG, Fisher DJ. Glutamate and N-Acetylaspartate Alterations Observed in Early Phase Psychosis: A Systematic Review of Proton Magnetic Resonance Spectroscopy Studies. Psychiatry Res Neuroimaging 2022; 321:111459. [PMID: 35183897 DOI: 10.1016/j.pscychresns.2022.111459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/03/2022] [Accepted: 02/07/2022] [Indexed: 11/27/2022]
Abstract
Glutamate and N-acetylaspartate have been investigated in the neuropathology of chronic schizophrenia, with fewer studies focusing on early phase psychosis. Additionally, there has been little review and synthesis of the literature focused on multiple brain regions. This systematic review aims to provide a clear report of the current state of research on glutamate and n-acetylaspartate concentrations in early phase psychosis (defined as the first five years following psychosis onset) in multiple brain regions. Existing literature was searched systematically to compile reports of glutamate/glutamate+glutamine (Glx) and n-acetylaspartate absolute levels and ratios in both male and female individuals with early phase psychosis. Reports on glutamate/Glx concentrations in the medial prefrontal region and thalamus were varied, but the majority of reports suggested no alterations in EPP. No studies reported glutamate alterations in the hippocampus or cerebellum. There was no evidence for n-acetylaspartate alterations in the caudate, basal ganglia, and medial prefrontal cortex, and minimal evidence for NAA reductions in the thalamus, anterior cingulate cortex, and hippocampus. Future research should focus on the regions that are less commonly reported, and should aim to explore possible confounds, such as medication status and substance use.
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Affiliation(s)
- J N Bissonnette
- Department of Psychiatry, Dalhousie University, Halifax, NS.
| | - A M Francis
- Department of Psychology, Saint Mary's University, Halifax, NS.
| | - S MacNeil
- Department of Psychology, Mount Saint Vincent University, Halifax, NS.
| | - C E Crocker
- Department of Psychiatry, Dalhousie University, Halifax, NS; Nova Scotia Early Psychosis Program, Halifax, NS; Department of Diagnostic Imaging, Dalhousie University, Halifax, NS.
| | - P G Tibbo
- Department of Psychiatry, Dalhousie University, Halifax, NS; Nova Scotia Early Psychosis Program, Halifax, NS.
| | - D J Fisher
- Department of Psychiatry, Dalhousie University, Halifax, NS; Department of Psychology, Saint Mary's University, Halifax, NS; Department of Psychology, Mount Saint Vincent University, Halifax, NS.
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Drosophila melanogaster Uncoupling Protein-4A (UCP4A) Catalyzes a Unidirectional Transport of Aspartate. Int J Mol Sci 2022; 23:ijms23031020. [PMID: 35162943 PMCID: PMC8834685 DOI: 10.3390/ijms23031020] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 12/23/2022] Open
Abstract
Uncoupling proteins (UCPs) form a distinct subfamily of the mitochondrial carrier family (MCF) SLC25. Four UCPs, DmUCP4A-C and DmUCP5, have been identified in Drosophila melanogaster on the basis of their sequence homology with mammalian UCP4 and UCP5. In a Parkinson’s disease model, DmUCP4A showed a protective role against mitochondrial dysfunction, by increasing mitochondrial membrane potential and ATP synthesis. To date, DmUCP4A is still an orphan of a biochemical function, although its possible involvement in mitochondrial uncoupling has been ruled out. Here, we show that DmUCP4A expressed in bacteria and reconstituted in phospholipid vesicles catalyzes a unidirectional transport of aspartate, which is saturable and inhibited by mercurials and other mitochondrial carrier inhibitors to various degrees. Swelling experiments carried out in yeast mitochondria have demonstrated that the unidirectional transport of aspartate catalyzed by DmUCP4 is not proton-coupled. The biochemical function of DmUCP4A has been further confirmed in a yeast cell model, in which growth has required an efflux of aspartate from mitochondria. Notably, DmUCP4A is the first UCP4 homolog from any species to be biochemically characterized. In Drosophila melanogaster, DmUCP4A could be involved in the transport of aspartate from mitochondria to the cytosol, in which it could be used for protein and nucleotide synthesis, as well as in the biosynthesis of ß-alanine and N-acetylaspartate, which play key roles in signal transmission in the central nervous system.
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Broeks MH, van Karnebeek CDM, Wanders RJA, Jans JJM, Verhoeven‐Duif NM. Inborn disorders of the malate aspartate shuttle. J Inherit Metab Dis 2021; 44:792-808. [PMID: 33990986 PMCID: PMC8362162 DOI: 10.1002/jimd.12402] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 05/08/2021] [Accepted: 05/12/2021] [Indexed: 12/12/2022]
Abstract
Over the last few years, various inborn disorders have been reported in the malate aspartate shuttle (MAS). The MAS consists of four metabolic enzymes and two transporters, one of them having two isoforms that are expressed in different tissues. Together they form a biochemical pathway that shuttles electrons from the cytosol into mitochondria, as the inner mitochondrial membrane is impermeable to the electron carrier NADH. By shuttling NADH across the mitochondrial membrane in the form of a reduced metabolite (malate), the MAS plays an important role in mitochondrial respiration. In addition, the MAS maintains the cytosolic NAD+ /NADH redox balance, by using redox reactions for the transfer of electrons. This explains why the MAS is also important in sustaining cytosolic redox-dependent metabolic pathways, such as glycolysis and serine biosynthesis. The current review provides insights into the clinical and biochemical characteristics of MAS deficiencies. To date, five out of seven potential MAS deficiencies have been reported. Most of them present with a clinical phenotype of infantile epileptic encephalopathy. Although not specific, biochemical characteristics include high lactate, high glycerol 3-phosphate, a disturbed redox balance, TCA abnormalities, high ammonia, and low serine, which may be helpful in reaching a diagnosis in patients with an infantile epileptic encephalopathy. Current implications for treatment include a ketogenic diet, as well as serine and vitamin B6 supplementation.
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Affiliation(s)
- Melissa H. Broeks
- Department of Genetics, Section Metabolic DiagnosticsUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Clara D. M. van Karnebeek
- Departments of PediatricsAmsterdam University Medical CenterAmsterdamThe Netherlands
- Department of Pediatrics, Amalia Children's Hospital, Radboud Center for Mitochondrial DiseasesRadboud University Medical CenterNijmegenThe Netherlands
- On behalf of “United for Metabolic Diseases”The Netherlands
| | - Ronald J. A. Wanders
- Departments of Pediatrics and Laboratory Medicine, Laboratory Genetic Metabolic DiseasesAmsterdam University Medical Center, University of AmsterdamAmsterdamThe Netherlands
| | - Judith J. M. Jans
- Department of Genetics, Section Metabolic DiagnosticsUniversity Medical Center UtrechtUtrechtThe Netherlands
- On behalf of “United for Metabolic Diseases”The Netherlands
| | - Nanda M. Verhoeven‐Duif
- Department of Genetics, Section Metabolic DiagnosticsUniversity Medical Center UtrechtUtrechtThe Netherlands
- On behalf of “United for Metabolic Diseases”The Netherlands
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Yang YQ, Meng FY, Liu X, Zhang M, Gu W, Yan HL, Yu J, Yang XX. Distinct metabonomic signatures of Polygoni Multiflori Radix Praeparata against glucolipid metabolic disorders. J Pharm Pharmacol 2021; 73:796-807. [PMID: 33734400 DOI: 10.1093/jpp/rgab012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 01/18/2021] [Indexed: 02/06/2023]
Abstract
OBJECTIVES Glucolipid metabolic disorders (GLMD) promote a series of major chronic diseases. Polygoni Multilori Radix Preparata (PMRP) has been widely acknowledged in the prevention and treatment of GLMD. We previously reported that water extract (WE) of PMRP and its major bioactive constituents such as polysaccharides (POL) and 2,3,5,4´-tetrahydroxy-stilbene-2-O-β-D-glucoside (TSG) could alleviate GLMD. The mitochondrial dysfunction is an important mechanism of GLMD, but the underlying mechanisms behind the regulation of mitochondria to alleviate GLMD by WE, POL from PMRP and TSG are still unknown. METHODS In this study, we elucidated the effects of WE, POL, and TSG towards regulating the mitochondrial dysfunction and alleviating GLMD using mitochondrial metabonomics. A rat model of GLMD was established by high-sugar and high-fat (HS-HF) diet. Rats were intragastrically given WE, POL, and TSG for 12 weeks. The liver mitochondrial metabolites were analyzed by ultra-high-performance liquid chromatography/mass spectrometry followed by multivariate statistical analysis to identify the differential metabolites and metabolic pathways. KEY FINDINGS The WE, POL, and TSG could significantly restore the level of endogenous metabolites in liver mitochondria toward normal status. In total, sixteen, seven, and fourteen differential metabolites were identified in the liver mitochondrial samples obtained from the WE, GOL, and TSG groups, respectively. These metabolites were found to be mainly involved in glycerol phospholipid, histidine, alanine, aspartic acid, glutamate metabolism, and arginine biosynthesis. CONCLUSIONS PMRP could improve the liver mitochondrial function by regulating the mitochondrial metabolic pathways to alleviate GLMD. Therefore, the application of PMRP might be a promising mitochondrial regulator/nutrient for alleviating GLMD-associated diseases and the mitochondrial metabonomics might provide insights into the evaluation of the efficacies and mechanisms of action of drugs.
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Affiliation(s)
- Ya-Qin Yang
- College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming, China
| | - Fan-Ying Meng
- College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming, China
| | - Xin Liu
- Beijing Entry-Exit Inspection and Quarantine Bureau, Beijing, China
| | - Mei Zhang
- College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming, China
| | - Wen Gu
- College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming, China
| | - Hong-Li Yan
- College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming, China
| | - Jie Yu
- College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming, China
| | - Xing-Xin Yang
- College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming, China
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βOHB Protective Pathways in Aralar-KO Neurons and Brain: An Alternative to Ketogenic Diet. J Neurosci 2020; 40:9293-9305. [PMID: 33087477 DOI: 10.1523/jneurosci.0711-20.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/24/2020] [Accepted: 08/29/2020] [Indexed: 12/19/2022] Open
Abstract
Aralar/AGC1/Slc25a12, the mitochondrial aspartate-glutamate carrier expressed in neurons, is the regulatory component of the NADH malate-aspartate shuttle. AGC1 deficiency is a neuropediatric rare disease characterized by hypomyelination, hypotonia, developmental arrest, and epilepsy. We have investigated whether β-hydroxybutyrate (βOHB), the main ketone body (KB) produced in ketogenic diet (KD), is neuroprotective in aralar-knock-out (KO) neurons and mice. We report that βOHB efficiently recovers aralar-KO neurons from deficits in basal-stimulated and glutamate-stimulated respiration, effects requiring βOHB entry into the neuron, and protects from glutamate excitotoxicity. Aralar-deficient mice were fed a KD to investigate its therapeutic potential early in development, but this approach was unfeasible. Therefore, aralar-KO pups were treated without distinction of gender with daily intraperitoneal injections of βOHB during 5 d. This treatment resulted in a recovery of striatal markers of the dopaminergic system including dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC)/DA ratio, and vesicular monoamine transporter 2 (VMAT2) protein. Regarding postnatal myelination, myelin basic protein (MBP) and myelin-associated glycoprotein (MAG) myelin proteins were markedly increased in the cortices of βOHB-treated aralar-KO mice. Although brain Asp and NAA levels did not change by βOHB administration, a 4-d βOHB treatment to aralar-KO, but not to control, neurons led to a substantial increase in Asp (3-fold) and NAA (4-fold) levels. These results suggest that the lack of increase in brain Asp and NAA is possibly because of its active utilization by the aralar-KO brain and the likely involvement of neuronal NAA in postnatal myelination in these mice. The effectiveness of βOHB as a therapeutic treatment in AGC1 deficiency deserves further investigation.SIGNIFICANCE STATEMENT Aralar deficiency induces a fatal phenotype in humans and mice and is associated with impaired neurodevelopment, epilepsy, and hypomyelination. In neurons, highly expressing aralar, its deficiency causes a metabolic blockade hampering mitochondrial energetics and respiration. Here, we find that βOHB, the main metabolic product in KD, recovers defective mitochondrial respiration bypassing the metabolic failure in aralar-deficient neurons. βOHB oxidation in mitochondria boosts the synthesis of cytosolic aspartate (Asp) and NAA, which is impeded by aralar deficiency, presumably through citrate-malate shuttle. In aralar-knock-out (KO) mice, βOHB recovers from the drastic drop in specific dopaminergic and myelin markers. The βOHB-induced myelin synthesis occurring together with the marked increment in neuronal NAA synthesis supports the role of NAA as a lipid precursor during postnatal myelination.
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Stecula A, Hussain MS, Viola RE. Discovery of Novel Inhibitors of a Critical Brain Enzyme Using a Homology Model and a Deep Convolutional Neural Network. J Med Chem 2020; 63:8867-8875. [DOI: 10.1021/acs.jmedchem.0c00473] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Adrian Stecula
- Atomwise Inc., San Francisco, California 94103, United States
| | - Muhammad S. Hussain
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606, United States
| | - Ronald E. Viola
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606, United States
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11
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Zyśk M, Sakowicz-Burkiewicz M, Pikul P, Kowalski R, Michno A, Pawełczyk T. The Impact of Acetyl-CoA and Aspartate Shortages on the N-Acetylaspartate Level in Different Models of Cholinergic Neurons. Antioxidants (Basel) 2020; 9:antiox9060522. [PMID: 32545833 PMCID: PMC7346116 DOI: 10.3390/antiox9060522] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 06/03/2020] [Accepted: 06/11/2020] [Indexed: 12/31/2022] Open
Abstract
N-acetylaspartate is produced by neuronal aspartate N-acetyltransferase (NAT8L) from acetyl-CoA and aspartate. In cholinergic neurons, acetyl-CoA is also utilized in the mitochondrial tricarboxylic acid cycle and in acetylcholine production pathways. While aspartate has to be shared with the malate–aspartate shuttle, another mitochondrial machinery together with the tricarboxylic acid cycle supports the electron transport chain turnover. The main goal of this study was to establish the impact of toxic conditions on N-acetylaspartate production. SN56 cholinergic cells were exposed to either Zn2+ overload or Ca2+ homeostasis dysregulation and male adult Wistar rats’ brains were studied after 2 weeks of challenge with streptozotocin-induced hyperglycemia or daily theophylline treatment. Our results allow us to hypothesize that the cholinergic neurons from brain septum prioritized the acetylcholine over N-acetylaspartate production. This report provides the first direct evidence for Zn2+-dependent suppression of N-acetylaspartate synthesis leading to mitochondrial acetyl-CoA and aspartate shortages. Furthermore, Zn2+ is a direct concentration-dependent inhibitor of NAT8L activity, while Zn2+-triggered oxidative stress is unlikely to be significant in such suppression.
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Affiliation(s)
- Marlena Zyśk
- Department of Molecular Medicine, Medical University of Gdansk, 80-211 Gdansk, Poland; (M.S.-B.); (T.P.)
- Correspondence: ; Tel.: +48-5834-927-70
| | - Monika Sakowicz-Burkiewicz
- Department of Molecular Medicine, Medical University of Gdansk, 80-211 Gdansk, Poland; (M.S.-B.); (T.P.)
| | - Piotr Pikul
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Center, Polish Academy of Science, 80-308 Gdansk, Poland;
- Clinical Laboratory University Clinical Center in Gdansk, 80-211 Gdansk, Poland;
| | - Robert Kowalski
- Clinical Laboratory University Clinical Center in Gdansk, 80-211 Gdansk, Poland;
| | - Anna Michno
- Department of Laboratory Medicine, Medical University of Gdansk, 80-2011 Gdansk, Poland;
| | - Tadeusz Pawełczyk
- Department of Molecular Medicine, Medical University of Gdansk, 80-211 Gdansk, Poland; (M.S.-B.); (T.P.)
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12
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Sen NE, Canet-Pons J, Halbach MV, Arsovic A, Pilatus U, Chae WH, Kaya ZE, Seidel K, Rollmann E, Mittelbronn M, Meierhofer D, De Zeeuw CI, Bosman LWJ, Gispert S, Auburger G. Generation of an Atxn2-CAG100 knock-in mouse reveals N-acetylaspartate production deficit due to early Nat8l dysregulation. Neurobiol Dis 2019; 132:104559. [PMID: 31376479 DOI: 10.1016/j.nbd.2019.104559] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/16/2019] [Accepted: 07/30/2019] [Indexed: 12/13/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disorder caused by CAG-expansion mutations in the ATXN2 gene, mainly affecting motor neurons in the spinal cord and Purkinje neurons in the cerebellum. While the large expansions were shown to cause SCA2, the intermediate length expansions lead to increased risk for several atrophic processes including amyotrophic lateral sclerosis and Parkinson variants, e.g. progressive supranuclear palsy. Intense efforts to pioneer a neuroprotective therapy for SCA2 require longitudinal monitoring of patients and identification of crucial molecular pathways. The ataxin-2 (ATXN2) protein is mainly involved in RNA translation control and regulation of nutrient metabolism during stress periods. The preferential mRNA targets of ATXN2 are yet to be determined. In order to understand the molecular disease mechanism throughout different prognostic stages, we generated an Atxn2-CAG100-knock-in (KIN) mouse model of SCA2 with intact murine ATXN2 expression regulation. Its characterization revealed somatic mosaicism of the expansion, with shortened lifespan, a progressive spatio-temporal pattern of pathology with subsequent phenotypes, and anomalies of brain metabolites such as N-acetylaspartate (NAA), all of which mirror faithfully the findings in SCA2 patients. Novel molecular analyses from stages before the onset of motor deficits revealed a strong selective effect of ATXN2 on Nat8l mRNA which encodes the enzyme responsible for NAA synthesis. This metabolite is a prominent energy store of the brain and a well-established marker for neuronal health. Overall, we present a novel authentic rodent model of SCA2, where in vivo magnetic resonance imaging was feasible to monitor progression and where the definition of earliest transcriptional abnormalities was possible. We believe that this model will not only reveal crucial insights regarding the pathomechanism of SCA2 and other ATXN2-associated disorders, but will also aid in developing gene-targeted therapies and disease prevention.
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Affiliation(s)
- Nesli-Ece Sen
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Júlia Canet-Pons
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Melanie V Halbach
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Aleksandar Arsovic
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Ulrich Pilatus
- Institute of Neuroradiology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Woon-Hyung Chae
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, 60596 Frankfurt am Main, Germany
| | - Zeynep-Ece Kaya
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany; Department of Neurology, Cerrahpasa School of Medicine, Istanbul University, 34098 Istanbul, Turkey
| | - Kay Seidel
- Department of Anatomy II, Institute of Clinical Neuroanatomy, Goethe University, 60590 Frankfurt am Main, Germany
| | - Ewa Rollmann
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Michel Mittelbronn
- Neurological Institute (Edinger Institute), Goethe University, 60590 Frankfurt am Main, Germany; Luxembourg Centre of Neuropathology (LCNP), Luxembourg; Department of Pathology, Laboratoire National de Santé (LNS), Dudelange, Luxembourg; Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Esch-sur-Alzette, Luxembourg; Department of Oncology, NORLUX Neuro-Oncology Laboratory, Luxembourg Institute of Health (LIH), Luxembourg
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Chris I De Zeeuw
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands; Department of Neuroscience, Erasmus Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Laurens W J Bosman
- Department of Neuroscience, Erasmus Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Suzana Gispert
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany.
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13
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Zyśk M, Bielarczyk H, Gul-Hinc S, Dyś A, Gapys B, Ronowska A, Sakowicz-Burkiewicz M, Szutowicz A. Phenotype-Dependent Interactions between N-acetyl-L-Aspartate and Acetyl-CoA in Septal SN56 Cholinergic Cells Exposed to an Excess of Zinc. J Alzheimers Dis 2018; 56:1145-1158. [PMID: 28106547 DOI: 10.3233/jad-160693] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Pyruvate dehydrogenase reaction utilizing glucose-derived pyruvate is an almost exclusive source of acetyl-CoA in different cell mitochondrial compartments of the brain. In neuronal mitochondria, the largest fraction of acetyl-CoA is utilized for energy production and the much smaller one for N-acetyl-L-aspartate (NAA) synthesis. Cholinergic neurons, unlike others, require additional amounts of acetyl-CoA for acetylcholine synthesis. Therefore, several neurotoxic signals, which inhibit pyruvate dehydrogenase, generate deeper shortages of acetyl-CoA and greater mortality of cholinergic neurons than noncholinergic ones. NAA is considered to be a marker of neuronal energy status in neuropathic brains. However, there is no data on putative differential fractional distribution of the acetyl-CoA pool between energy producing and NAA or acetylcholine synthesizing pathways in noncholinergic and cholinergic neurons, respectively. Therefore, the aim of this study was to investigate whether zinc-excess, a common excitotoxic signal, may evoke differential effects on the NAA metabolism in neuronal cells with low and high expression of the cholinergic phenotype. Differentiated SN56 neuronal cells, displaying a high activity of choline acetyltransferase and rates of acetylcholine synthesis, contained lower levels of acetyl-CoA and NAA, being more susceptible to ZnCl2 exposition that the nondifferentiated SN56 or differentiated dopaminergic SHSY5Y neuronal and astroglial C6 cells. Differentiated SN56 accumulated greater amounts of Zn2 + from extracellular space than the other ones, and displayed a stronger suppression of pyruvate dehydrogenase complex activity and acetyl-CoA, NAA, ATP, acetylcholine levels, and loss of viability. These data indicate that the acetyl-CoA synthesizing system in neurons constitutes functional unity with energy generating and NAA or acetylcholine pathways of its utilization, which are uniformly affected by neurotoxic conditions.
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Affiliation(s)
- Marlena Zyśk
- Department of Laboratory Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Hanna Bielarczyk
- Department of Laboratory Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Sylwia Gul-Hinc
- Department of Laboratory Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Aleksandra Dyś
- Department of Laboratory Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Beata Gapys
- Department of Laboratory Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Anna Ronowska
- Department of Laboratory Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | | | - Andrzej Szutowicz
- Department of Laboratory Medicine, Medical University of Gdańsk, Gdańsk, Poland
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14
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Profilo E, Peña-Altamira LE, Corricelli M, Castegna A, Danese A, Agrimi G, Petralla S, Giannuzzi G, Porcelli V, Sbano L, Viscomi C, Massenzio F, Palmieri EM, Giorgi C, Fiermonte G, Virgili M, Palmieri L, Zeviani M, Pinton P, Monti B, Palmieri F, Lasorsa FM. Down-regulation of the mitochondrial aspartate-glutamate carrier isoform 1 AGC1 inhibits proliferation and N-acetylaspartate synthesis in Neuro2A cells. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1422-1435. [DOI: 10.1016/j.bbadis.2017.02.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 02/02/2017] [Accepted: 02/20/2017] [Indexed: 12/26/2022]
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15
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Fasinu P, Choonara YE, Kumar P, du Toit LC, Bijukumar D, Khan RA, Pillay V. Enhancement of the Oral Bioavailability of Felodipine Employing 8-Arm-Poly(Ethylene Glycol): In Vivo, In Vitro and In Silico Evaluation. AAPS PharmSciTech 2017; 18:617-628. [PMID: 27173987 DOI: 10.1208/s12249-016-0545-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/28/2016] [Indexed: 11/30/2022] Open
Abstract
Poor oral bioavailability is the single most important challenge in drug delivery. Prominent among the factors responsible for this is metabolic activity of the intestinal and hepatic cytochrome P450 (CYP450) enzymes. In preliminary studies, it was demonstrated that 8-arm-PEG was able to inhibit the felodipine metabolism. Therefore, this report investigated the oral bioavailability-enhancing property of 8-arm-PEG employing detailed in vitro, in vivo, and in silico evaluations. The in vitro metabolism of felodipine by cytochrome P450 3A4-expressed human liver microsomes (HLM) was optimized yielding a typical Michaelis-Menten plot through the application of Enzyme Kinetic Module software from where the enzyme kinetic parameters were determined. In vitro investigation of 8-arm-poly(ethylene glycol) against CYP3A4-catalyzed felodipine metabolism employing human liver microsomes compared closely with naringenin, a typical grapefruit flavonoid, yielding IC50 values of 7.22 and 121.97 μM, respectively. The investigated potential of 8-arm-poly(ethylene glycol) in oral drug delivery yielded satisfactory in vitro drug release results. The in vivo studies of the effects of 8-arm-poly(ethylene glycol) on the oral bioavailability of felodipine as performed in the Large White pig model showed a >100% increase in plasma felodipine levels compared to controls, with no apparent effect on systemic felodipine clearance. The outcome of this research presents a novel CYP3A4 inhibitor, 8-arm-poly(ethylene glycol) for oral bioavailability enhancement.
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16
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Dahlin M, Martin DA, Hedlund Z, Jonsson M, von Döbeln U, Wedell A. The ketogenic diet compensates for AGC1 deficiency and improves myelination. Epilepsia 2015; 56:e176-81. [PMID: 26401995 DOI: 10.1111/epi.13193] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2015] [Indexed: 11/28/2022]
Abstract
The brain aspartate-glutamate carrier (AGC1) is specifically expressed in neurons, where it transports aspartate from the mitochondria to the cytosol, and plays a role in transfer of nicotinamide adenine dinucleotide (NADH)-reducing equivalents into the mitochondria as a part of the malate-aspartate shuttle. Deficient function of AGC1 underlies an inborn error of metabolism that presents with severe hypotonia, arrested psychomotor development, and seizures from a few months of age. In AGC1 deficiency, there is secondary hypomyelination due to lack of N-acetylaspartate (NAA), which is normally generated by acetylation of aspartate in the neuron and required for fatty acid synthesis by the adjacent oligodendrocyte. Based on experiences from AGC2 deficiency, we predicted that reduced glycolysis should compensate for the metabolic defect and allow resumed myelination in AGC1 deficiency. Carbohydrate restriction was therefore initiated in a patient with AGC1 deficiency at 6 years of age by introducing a ketogenic diet. The response was dramatic, clinically as well as radiologically. Psychomotor development showed clear improvement, and magnetic resonance imaging (MRI) indicated resumed myelination. This is the first successful treatment of secondary hypomyelination reported. Because AGC1 is driven by the proton gradient generated by the neuronal mitochondrial respiratory chain, the results have potential relevance for secondary hypomyelination in general.
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Affiliation(s)
- Maria Dahlin
- Department of Women's and Children's Health, Karolinska Institute, Stockholm, Sweden.,Department of Neuropediatrics, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Daniel A Martin
- Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden
| | - Zandra Hedlund
- Department of Nutrition, Karolinska University Hospital, Stockholm, Sweden
| | - Monica Jonsson
- Center of Child Neurology and Habilitation, Östersund Hospital, Östersund, Sweden
| | - Ulrika von Döbeln
- Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.,Center for Inherited Metabolic Diseases (CMMS), Karolinska University Hospital, Stockholm, Sweden
| | - Anna Wedell
- Center for Inherited Metabolic Diseases (CMMS), Karolinska University Hospital, Stockholm, Sweden.,Department of Molecular Medicine and Surgery, Science for Life Laboratory, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
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17
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Zhang Y, Han Y, Wang Y, Zhang Y, Li L, Jin E, Deng L, Watts B, Golden T, Wu N. A MRS study of metabolic alterations in the frontal white matter of major depressive disorder patients with the treatment of SSRIs. BMC Psychiatry 2015; 15:99. [PMID: 25934495 PMCID: PMC4458012 DOI: 10.1186/s12888-015-0489-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 04/24/2015] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Proton magnetic resonance spectroscopy provides a non-invasive technology to study brain metabolite levels in vivo, which can be used to measure biochemical compounds or metabolite concentrations in circumscribed brain regions. Previous research has highlighted the role of glial cells in brain white matter. It has been assumed that antidepressant treatment with SSRIs not only affects neurons, but also activates glial cells. This study focused on the observation of any potential changes in the metabolite levels of the ventral prefrontal white matter in major depressive disorder (MDD) patients who have received antidepressant treatment. METHODS 17 female patients diagnosed as MDD according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria with the scores of 18 and above on the 24-item Hamilton Depression Rating Scale (HDRS) were recruited. MRS studies were performed on a 3.0 T MR system, single voxel PRESS spectroscopy with chemical-shift selective saturation water suppression. The volume of interest was localized at the bilateral ventral prefrontal white matter regions (voxel size: 2 × 2 × 2 mm(3)). The spectral data analysis was performed by using the instrument manufacturer supplied software. RESULTS The bilateral ventral prefrontal white matter of MDD patients showed significantly lower Cho/Cr (p < 0.05) before receiving treatment. The HDRS, as the indicator of treatment response, showed a significant decrease in patients who had gone through 12 weeks treatment (p < 0.01). The bilateral Cho/Cr values of post-treatment patients were increased significantly compared to that of pre-treatment (p < 0.05). CONCLUSION The alteration of ventral prefrontal white matter metabolite levels are likely involved in MDD pathophysiology and imply a crucial role of white matter in MDD.
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Affiliation(s)
- Yifan Zhang
- Department of Traditional Chinese Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yong-An Road, Beijing, 100050, China.
| | - Yu Han
- Department of Traditional Chinese Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yong-An Road, Beijing, 100050, China.
| | - Yongzhi Wang
- Department of Traditional Chinese Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yong-An Road, Beijing, 100050, China.
| | - Yinfeng Zhang
- Department of Traditional Chinese Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yong-An Road, Beijing, 100050, China.
| | - Li Li
- Department of Traditional Chinese Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yong-An Road, Beijing, 100050, China.
| | - Erhu Jin
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China.
| | - Ligang Deng
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China.
| | - Brandi Watts
- Department of Biological Sciences, Southeastern Oklahoma State University, Durant, OK, 74701, USA.
| | - Teresa Golden
- Department of Biological Sciences, Southeastern Oklahoma State University, Durant, OK, 74701, USA.
| | - Ning Wu
- Department of Biological Sciences, Southeastern Oklahoma State University, Durant, OK, 74701, USA.
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18
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Menga A, Iacobazzi V, Infantino V, Avantaggiati ML, Palmieri F. The mitochondrial aspartate/glutamate carrier isoform 1 gene expression is regulated by CREB in neuronal cells. Int J Biochem Cell Biol 2015; 60:157-66. [PMID: 25597433 PMCID: PMC4344217 DOI: 10.1016/j.biocel.2015.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 12/04/2014] [Accepted: 01/06/2015] [Indexed: 12/22/2022]
Abstract
The aspartate/glutamate carrier isoform 1 is an essential mitochondrial transporter that exchanges intramitochondrial aspartate and cytosolic glutamate across the inner mitochondrial membrane. It is expressed in brain, heart and muscle and is involved in important biological processes, including myelination. However, the signals that regulate the expression of this transporter are still largely unknown. In this study we first identify a CREB binding site within the aspartate/glutamate carrier gene promoter that acts as a strong enhancer element in neuronal SH-SY5Y cells. This element is regulated by active, phosphorylated CREB protein and by signal pathways that modify the activity of CREB itself and, most noticeably, by intracellular Ca(2+) levels. Specifically, aspartate/glutamate carrier gene expression is induced via CREB by forskolin while it is inhibited by the PKA inhibitor, H89. Furthermore, the CREB-induced activation of gene expression is increased by thapsigargin, which enhances cytosolic Ca(2+), while it is inhibited by BAPTA-AM that reduces cytosolic Ca(2+) or by STO-609, which inhibits CaMK-IV phosphorylation. We further show that CREB-dependent regulation of aspartate/glutamate carrier gene expression occurs in neuronal cells in response to pathological (inflammation) and physiological (differentiation) conditions. Since this carrier is necessary for neuronal functions and is involved in myelinogenesis, our results highlight that targeting of CREB activity and Ca(2+) might be therapeutically exploited to increase aspartate/glutamate carrier gene expression in neurodegenerative diseases.
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Affiliation(s)
- Alessio Menga
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125 Bari, Italy
| | - Vito Iacobazzi
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125 Bari, Italy
| | - Vittoria Infantino
- Department of Science, University of Basilicata, Via N. Sauro 85, 85100 Potenza, Italy
| | - Maria Laura Avantaggiati
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA
| | - Ferdinando Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125 Bari, Italy.
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19
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Igarashi H, Suzuki Y, Huber VJ, Ida M, Nakada T. N-acetylaspartate decrease in acute stage of ischemic stroke: a perspective from experimental and clinical studies. Magn Reson Med Sci 2014; 14:13-24. [PMID: 25500779 DOI: 10.2463/mrms.2014-0039] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
N-acetylaspartate (NAA) appears in a prominent peak in proton magnetic resonance spectroscopy ((1)H-MRS) of the brain. Exhibition by NAA of time-dependent attenuation that reflects energy metabolism during the acute stage of cerebral ischemia makes this metabolite a unique biomarker for assessing ischemic stroke. Although magnetic resonance (MR) imaging is a powerful technique for inspecting the pathological changes that occur during ischemic stroke, biomarkers that directly reflect the drastic metabolic changes associated with acute-stage ischemia are strongly warranted for appropriate therapeutic decision-making in daily clinical settings. In this review, we provide a brief overview of NAA metabolism and focus on the use of attenuation in NAA as a means for assessing the pathophysiological changes that occur during the acute stage of ischemic stroke.
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Affiliation(s)
- Hironaka Igarashi
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata
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20
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Hirrlinger J, Nave KA. Adapting brain metabolism to myelination and long-range signal transduction. Glia 2014; 62:1749-61. [DOI: 10.1002/glia.22737] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 07/23/2014] [Accepted: 07/23/2014] [Indexed: 12/24/2022]
Affiliation(s)
- Johannes Hirrlinger
- Department of Neurogenetics; Max-Planck-Institute for Experimental Medicine; Göttingen Germany
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig; Leipzig Germany
| | - Klaus-Armin Nave
- Department of Neurogenetics; Max-Planck-Institute for Experimental Medicine; Göttingen Germany
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21
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Moffett JR, Arun P, Ariyannur PS, Namboodiri AMA. N-Acetylaspartate reductions in brain injury: impact on post-injury neuroenergetics, lipid synthesis, and protein acetylation. FRONTIERS IN NEUROENERGETICS 2013; 5:11. [PMID: 24421768 PMCID: PMC3872778 DOI: 10.3389/fnene.2013.00011] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 12/09/2013] [Indexed: 12/22/2022]
Abstract
N-Acetylaspartate (NAA) is employed as a non-invasive marker for neuronal health using proton magnetic resonance spectroscopy (MRS). This utility is afforded by the fact that NAA is one of the most concentrated brain metabolites and that it produces the largest peak in MRS scans of the healthy human brain. NAA levels in the brain are reduced proportionately to the degree of tissue damage after traumatic brain injury (TBI) and the reductions parallel the reductions in ATP levels. Because NAA is the most concentrated acetylated metabolite in the brain, we have hypothesized that NAA acts in part as an extensive reservoir of acetate for acetyl coenzyme A synthesis. Therefore, the loss of NAA after TBI impairs acetyl coenzyme A dependent functions including energy derivation, lipid synthesis, and protein acetylation reactions in distinct ways in different cell populations. The enzymes involved in synthesizing and metabolizing NAA are predominantly expressed in neurons and oligodendrocytes, respectively, and therefore some proportion of NAA must be transferred between cell types before the acetate can be liberated, converted to acetyl coenzyme A and utilized. Studies have indicated that glucose metabolism in neurons is reduced, but that acetate metabolism in astrocytes is increased following TBI, possibly reflecting an increased role for non-glucose energy sources in response to injury. NAA can provide additional acetate for intercellular metabolite trafficking to maintain acetyl CoA levels after injury. Here we explore changes in NAA, acetate, and acetyl coenzyme A metabolism in response to brain injury.
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Affiliation(s)
- John R. Moffett
- Neuroscience Program, Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health SciencesBethesda, MD, USA
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22
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Pessentheiner AR, Pelzmann HJ, Walenta E, Schweiger M, Groschner LN, Graier WF, Kolb D, Uno K, Miyazaki T, Nitta A, Rieder D, Prokesch A, Bogner-Strauss JG. NAT8L (N-acetyltransferase 8-like) accelerates lipid turnover and increases energy expenditure in brown adipocytes. J Biol Chem 2013; 288:36040-51. [PMID: 24155240 PMCID: PMC3861652 DOI: 10.1074/jbc.m113.491324] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
NAT8L (N-acetyltransferase 8-like) catalyzes the formation of N-acetylaspartate (NAA) from acetyl-CoA and aspartate. In the brain, NAA delivers the acetate moiety for synthesis of acetyl-CoA that is further used for fatty acid generation. However, its function in other tissues remained elusive. Here, we show for the first time that Nat8l is highly expressed in adipose tissues and murine and human adipogenic cell lines and is localized in the mitochondria of brown adipocytes. Stable overexpression of Nat8l in immortalized brown adipogenic cells strongly increases glucose incorporation into neutral lipids, accompanied by increased lipolysis, indicating an accelerated lipid turnover. Additionally, mitochondrial mass and number as well as oxygen consumption are elevated upon Nat8l overexpression. Concordantly, expression levels of brown marker genes, such as Prdm16, Cidea, Pgc1α, Pparα, and particularly UCP1, are markedly elevated in these cells. Treatment with a PPARα antagonist indicates that the increase in UCP1 expression and oxygen consumption is PPARα-dependent. Nat8l knockdown in brown adipocytes has no impact on cellular triglyceride content, lipogenesis, or oxygen consumption, but lipolysis and brown marker gene expression are increased; the latter is also observed in BAT of Nat8l-KO mice. Interestingly, the expression of ATP-citrate lyase is increased in Nat8l-silenced adipocytes and BAT of Nat8l-KO mice, indicating a compensatory mechanism to sustain the acetyl-CoA pool once Nat8l levels are reduced. Taken together, our data show that Nat8l impacts on the brown adipogenic phenotype and suggests the existence of the NAT8L-driven NAA metabolism as a novel pathway to provide cytosolic acetyl-CoA for lipid synthesis in adipocytes.
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Affiliation(s)
- Ariane R. Pessentheiner
- From the Institute for Genomics and Bioinformatics, Graz University of Technology, Petergasse 14, 8010 Graz, Austria, ,the Institute of Biochemistry, Graz University of Technology, Petergasse 12, 8010 Graz, Austria
| | - Helmut J. Pelzmann
- From the Institute for Genomics and Bioinformatics, Graz University of Technology, Petergasse 14, 8010 Graz, Austria, ,the Institute of Biochemistry, Graz University of Technology, Petergasse 12, 8010 Graz, Austria
| | - Evelyn Walenta
- From the Institute for Genomics and Bioinformatics, Graz University of Technology, Petergasse 14, 8010 Graz, Austria
| | - Martina Schweiger
- the Institute for Molecular Biosciences, University of Graz, Heinrichstrasse 31, 8010 Graz, Austria
| | | | | | - Dagmar Kolb
- Institute of Cell Biology, Histology, and Embryology, Medical University of Graz, Harrachgasse 21, 8010 Graz, Austria, ,the Core Facility Ultrastructure Analysis, Center for Medical Research, Medical University of Graz, Stiftingtalstrasse 24, 8010 Graz, Austria
| | - Kyosuke Uno
- the Department of Pharmaceutical Therapy and Neuropharmacology, Faculty of Pharmaceutical Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan, and
| | - Toh Miyazaki
- the Department of Pharmaceutical Therapy and Neuropharmacology, Faculty of Pharmaceutical Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan, and
| | - Atsumi Nitta
- the Department of Pharmaceutical Therapy and Neuropharmacology, Faculty of Pharmaceutical Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan, and
| | - Dietmar Rieder
- the Division of Bioinformatics, Biocenter, Innsbruck Medical University, Innrain 80, 6020 Innsbruck, Austria
| | - Andreas Prokesch
- From the Institute for Genomics and Bioinformatics, Graz University of Technology, Petergasse 14, 8010 Graz, Austria, ,the Institute of Biochemistry, Graz University of Technology, Petergasse 12, 8010 Graz, Austria
| | - Juliane G. Bogner-Strauss
- From the Institute for Genomics and Bioinformatics, Graz University of Technology, Petergasse 14, 8010 Graz, Austria, ,the Institute of Biochemistry, Graz University of Technology, Petergasse 12, 8010 Graz, Austria, , To whom correspondence should be addressed: Petersgasse 14/5, 8010 Graz, Austria. Tel.: 43-316-873-5337; E-mail:
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23
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Su K, Bourdette D, Forte M. Mitochondrial dysfunction and neurodegeneration in multiple sclerosis. Front Physiol 2013; 4:169. [PMID: 23898299 PMCID: PMC3722885 DOI: 10.3389/fphys.2013.00169] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 06/18/2013] [Indexed: 12/31/2022] Open
Abstract
Multiple sclerosis (MS) has traditionally been considered an autoimmune inflammatory disorder leading to demyelination and clinical debilitation as evidenced by our current standard anti-inflammatory and immunosuppressive treatment regimens. While these approaches do control the frequency of clinical relapses, they do not prevent the progressive functional decline that plagues many people with MS. Many avenues of research indicate that a neurodegenerative process may also play a significant role in MS from the early stages of disease, and one of the current hypotheses identifies mitochondrial dysfunction as a key contributing mechanism. We have hypothesized that pathological permeability transition pore (PTP) opening mediated by reactive oxygen species (ROS) and calcium dysregulation is central to mitochondrial dysfunction and neurodegeneration in MS. This focused review highlights recent evidence supporting this hypothesis, with particular emphasis on our in vitro and in vivo work with the mitochondria-targeted redox enzyme p66ShcA.
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Affiliation(s)
- Kimmy Su
- Vollum Institute, Oregon Health and Science University Portland, OR, USA ; Department of Neurology, Oregon Health and Science University Portland, OR, USA
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24
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Long PM, Moffett JR, Namboodiri AMA, Viapiano MS, Lawler SE, Jaworski DM. N-acetylaspartate (NAA) and N-acetylaspartylglutamate (NAAG) promote growth and inhibit differentiation of glioma stem-like cells. J Biol Chem 2013; 288:26188-26200. [PMID: 23884408 DOI: 10.1074/jbc.m113.487553] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Metabolic reprogramming is a pathological feature of cancer and a driver of tumor cell transformation. N-Acetylaspartate (NAA) is one of the most abundant amino acid derivatives in the brain and serves as a source of metabolic acetate for oligodendrocyte myelination and protein/histone acetylation or a precursor for the synthesis of the neurotransmitter N-acetylaspartylglutamate (NAAG). NAA and NAAG as well as aspartoacylase (ASPA), the enzyme responsible for NAA degradation, are significantly reduced in glioma tumors, suggesting a possible role for decreased acetate metabolism in tumorigenesis. This study sought to examine the effects of NAA and NAAG on primary tumor-derived glioma stem-like cells (GSCs) from oligodendroglioma as well as proneural and mesenchymal glioblastoma, relative to oligodendrocyte progenitor cells (Oli-Neu). Although the NAA dicarboxylate transporter NaDC3 is primarily thought to be expressed by astrocytes, all cell lines expressed NaDC3 and, thus, are capable of NAA up-take. Treatment with NAA or NAAG significantly increased GSC growth and suppressed differentiation of Oli-Neu cells and proneural GSCs. Interestingly, ASPA was expressed in both the cytosol and nuclei of GSCs and exhibited greatest nuclear immunoreactivity in differentiation-resistant GSCs. Both NAA and NAAG elicited the expression of a novel immunoreactive ASPA species in select GSC nuclei, suggesting differential ASPA regulation in response to these metabolites. Therefore, this study highlights a potential role for nuclear ASPA expression in GSC malignancy and suggests that the use of NAA or NAAG is not an appropriate therapeutic approach to increase acetate bioavailability in glioma. Thus, an alternative acetate source is required.
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Affiliation(s)
- Patrick M Long
- From the Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, Vermont 05405
| | - John R Moffett
- the Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, and
| | - Aryan M A Namboodiri
- the Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, and
| | - Mariano S Viapiano
- the Department of Neurosurgery, Brigham and Women's Hospital, Boston, Massachusetts 02215
| | - Sean E Lawler
- the Department of Neurosurgery, Brigham and Women's Hospital, Boston, Massachusetts 02215
| | - Diane M Jaworski
- From the Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, Vermont 05405,.
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Leone P, Shera D, McPhee SWJ, Francis JS, Kolodny EH, Bilaniuk LT, Wang DJ, Assadi M, Goldfarb O, Goldman HW, Freese A, Young D, During MJ, Samulski RJ, Janson CG. Long-term follow-up after gene therapy for canavan disease. Sci Transl Med 2013; 4:165ra163. [PMID: 23253610 DOI: 10.1126/scitranslmed.3003454] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Canavan disease is a hereditary leukodystrophy caused by mutations in the aspartoacylase gene (ASPA), leading to loss of enzyme activity and increased concentrations of the substrate N-acetyl-aspartate (NAA) in the brain. Accumulation of NAA results in spongiform degeneration of white matter and severe impairment of psychomotor development. The goal of this prospective cohort study was to assess long-term safety and preliminary efficacy measures after gene therapy with an adeno-associated viral vector carrying the ASPA gene (AAV2-ASPA). Using noninvasive magnetic resonance imaging and standardized clinical rating scales, we observed Canavan disease in 28 patients, with a subset of 13 patients being treated with AAV2-ASPA. Each patient received 9 × 10(11) vector genomes via intraparenchymal delivery at six brain infusion sites. Safety data collected over a minimum 5-year follow-up period showed a lack of long-term adverse events related to the AAV2 vector. Posttreatment effects were analyzed using a generalized linear mixed model, which showed changes in predefined surrogate markers of disease progression and clinical assessment subscores. AAV2-ASPA gene therapy resulted in a decrease in elevated NAA in the brain and slowed progression of brain atrophy, with some improvement in seizure frequency and with stabilization of overall clinical status.
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Affiliation(s)
- Paola Leone
- Department of Cell Biology, Cell & Gene Therapy Center, University of Medicine & Dentistry of New Jersey, Stratford, NJ 08034, USA.
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He ZL, Deng W, Li ML, Chen ZF, Collier DA, Ma X, Li T. Detection of metabolites in the white matter of frontal lobes and hippocampus with proton in first-episode treatment-naïve schizophrenia patients. Early Interv Psychiatry 2012; 6:166-75. [PMID: 21951785 DOI: 10.1111/j.1751-7893.2011.00291.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM This study aimed to investigate the changes of the metabolites in the white matter of frontal lobes and hippocampus in schizophrenia by using proton magnetic resonance spectroscopy ((1) H-MRS). METHODS Sixty-three first-episode treatment-naïve schizophrenia (FES) patients and 63 age-, gender- and education level-matched healthy controls were recruited. The relative levels of metabolites including N-acetylaspartate (NAA), choline-containing compounds (Cho), (Cr) and myo-inositol (MI) were detected with (1) H-MRS, and the laterality index (Li) was calculated. The severity of symptoms was assessed using the Positive and Negative Syndrome Scale. RESULTS Compared with controls, FES patients did not show significant differences in all metabolites. The severity of positive symptoms was negatively correlated with the NAA/Cho in the white matter of the left frontal lobe and positively correlated with the Cho/Cr in the right white matter of frontal lobes. A negative correlation was observed between the severity of negative symptoms and the NAA/Cr in the white matter of bilateral frontal lobes. No difference was shown in the Li of metabolites between FES patients and controls. CONCLUSIONS The metabolites such as NAA, Cho and MI in white matter of frontal lobes and hippocampus were not significantly altered in FES patients. The lower axonal integrity/number (NAA concentration) may be associated with more severe negative symptoms, and dysmetabolism in process of myelination in the white matter of frontal lobes associated with more severe positive symptoms.
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Affiliation(s)
- Zong-Ling He
- The Mental Health Center and the Psychiatric Laboratory, West China Hospital, Sichuan University, Chengdu, Sichuan, China
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Determinants of the enzymatic activity and the subcellular localization of aspartate N-acetyltransferase. Biochem J 2011; 441:105-12. [DOI: 10.1042/bj20111179] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Aspartate N-acetyltransferase (NAT8L, N-acetyltransferase 8-like), the enzyme that synthesizes N-acetylaspartate, is membrane-bound and is at least partially associated with the ER (endoplasmic reticulum). The aim of the present study was to determine which regions of the protein are important for its catalytic activity and its subcellular localization. Transfection of truncated forms of NAT8L into HEK (human embryonic kidney)-293T cells indicated that the 68 N-terminal residues (regions 1 and 2) have no importance for the catalytic activity and the subcellular localization of this enzyme, which was exclusively associated with the ER. Mutation of conserved residues that precede (Arg81 and Glu101, in region 3) or follow (Asp168 and Arg220, in region 5) the putative membrane region (region 4) markedly affected the kinetic properties, suggesting that regions 3 and 5 form the catalytic domain and that the membrane region has a loop structure. Evidence is provided for the membrane region comprising α-helices and the catalytic site being cytosolic. Transfection of chimaeric proteins in which GFP (green fluorescent protein) was fused to different regions of NAT8L indicated that the membrane region (region 4) is necessary and sufficient to target NAT8L to the ER. Thus NAT8L is targeted to the ER membrane by a hydrophobic loop that connects two regions of the catalytic domain.
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Abstract
Amino acids are essential building blocks of all mammalian cells. In addition to their role in protein synthesis, amino acids play an important role as energy fuels, precursors for a variety of metabolites and as signalling molecules. Disorders associated with the malfunction of amino acid transporters reflect the variety of roles that they fulfil in human physiology. Mutations of brain amino acid transporters affect neuronal excitability. Mutations of renal and intestinal amino acid transporters affect whole-body homoeostasis, resulting in malabsorption and renal problems. Amino acid transporters that are integral parts of metabolic pathways reduce the function of these pathways. Finally, amino acid uptake is essential for cell growth, thereby explaining their role in tumour progression. The present review summarizes the involvement of amino acid transporters in these roles as illustrated by diseases resulting from transporter malfunction.
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31
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Goto N, Yoshimura R, Kakeda S, Moriya J, Hayashi K, Ikenouchi-Sugita A, Umene-Nakano W, Hori H, Ueda N, Korogi Y, Nakamura J. Comparison of brain N-acetylaspartate levels and serum brain-derived neurotrophic factor (BDNF) levels between patients with first-episode schizophrenia psychosis and healthy controls. Eur Psychiatry 2011; 26:57-63. [PMID: 20434315 DOI: 10.1016/j.eurpsy.2009.10.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2009] [Revised: 09/17/2009] [Accepted: 10/09/2009] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND N-acetylaspartate (NAA) levels and serum brain-derived neurotrophic factor (BDNF) levels in patients with first-episode schizophrenia psychosis and age- and sex-matched healthy control subjects were investigated. In addition, plasma levels of homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) were compared between the two groups. METHOD Eighteen patients (nine males, nine females; age range: 13-52 years) were enrolled in the study, and 18 volunteers (nine males, nine females; age range: 15-49 years) with no current or past psychiatric history were also studied by magnetic resonance spectroscopy (MRS) as sex- and age-matched controls. RESULTS Levels of NAA/Cr in the left basal ganglia (p=0.0065) and parieto-occipital lobe (p=0.00498), but not in the frontal lobe, were significantly lower in patients with first-episode schizophrenia psychosis than in control subjects. No difference was observed between the serum BDNF levels of patients with first-episode schizophrenia psychosis and control subjects. In regard to the plasma levels of catecholamine metabolites, plasma MHPG, but not HVA, was significantly lower in the patients with first-episode psychosis than in control subjects. In addition, a significantly positive correlation was observed between the levels of NAA/Cr of the left basal ganglia and plasma MHPG in all subjects. CONCLUSION These results suggest that brain NAA levels in the left basal ganglia and plasma MHPG levels were significantly reduced at the first episode of schizophrenia psychosis, indicating that neurodegeneration via noradrenergic neurons might be associated with the initial progression of the disease.
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Affiliation(s)
- N Goto
- Department of Psychiatry and Radiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 8078555, Japan
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Menon KN, Steer DL, Short M, Petratos S, Smith I, Bernard CCA. A novel unbiased proteomic approach to detect the reactivity of cerebrospinal fluid in neurological diseases. Mol Cell Proteomics 2011; 10:M110.000042. [PMID: 21421798 DOI: 10.1074/mcp.m110.000042] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Neurodegenerative diseases, such as multiple sclerosis represent global health issues. Accordingly, there is an urgent need to understand the pathogenesis of this and other central nervous system disorders, so that more effective therapeutics can be developed. Cerebrospinal fluid is a potential source of important reporter molecules released from various cell types as a result of central nervous system pathology. Here, we report the development of an unbiased approach for the detection of reactive cerebrospinal fluid molecules and target brain proteins from patients with multiple sclerosis. To help identify molecules that may serve as clinical biomarkers for multiple sclerosis, we have biotinylated proteins present in the cerebrospinal fluid and tested their reactivity against brain homogenate as well as myelin and myelin-axolemmal complexes. Proteins were separated by two-dimensional gel electrophoresis, blotted onto membranes and probed separately with biotinylated unprocessed cerebrospinal fluid samples. Protein spots that reacted to two or more multiple sclerosis-cerebrospinal fluids were further analyzed by matrix assisted laser desorption ionization-time-of-flight time-of-flight mass spectrometry. In addition to previously reported proteins found in multiple sclerosis cerebrospinal fluid, such as αβ crystallin, enolase, and 14-3-3-protein, we have identified several additional molecules involved in mitochondrial and energy metabolism, myelin gene expression and/or cytoskeletal organization. These include aspartate aminotransferase, cyclophilin-A, quaking protein, collapsin response mediator protein-2, ubiquitin carboxy-terminal hydrolase L1, and cofilin. To further validate these findings, the cellular expression pattern of collapsin response mediator protein-2 and ubiquitin carboxy-terminal hydrolase L1 were investigated in human chronic-active MS lesions by immunohistochemistry. The observation that in multiple sclerosis lesions phosphorylated collapsin response mediator protein-2 was increased, whereas Ubiquitin carboxy-terminal hydrolase L1 was down-regulated, not only highlights the importance of these molecules in the pathology of this disease, but also illustrates the use of our approach in attempting to decipher the complex pathological processes leading to multiple sclerosis and other neurodegenerative diseases.
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Affiliation(s)
- Krishnakumar N Menon
- Monash Immunology and Stem Cell Laboratories, Monash University, Clayton, Victoria, Australia.
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Ariyannur PS, Moffett JR, Madhavarao CN, Arun P, Vishnu N, Jacobowitz DM, Hallows WC, Denu JM, Namboodiri AMA. Nuclear-cytoplasmic localization of acetyl coenzyme a synthetase-1 in the rat brain. J Comp Neurol 2010; 518:2952-77. [PMID: 20533355 DOI: 10.1002/cne.22373] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Acetyl coenzyme A synthetase-1 (AceCS1) catalyzes the synthesis of acetyl coenzyme A from acetate and coenzyme A and is thought to play diverse roles ranging from fatty acid synthesis to gene regulation. By using an affinity-purified antibody generated against an 18-mer peptide sequence of AceCS1 and a polyclonal antibody directed against recombinant AceCS1 protein, we examined the expression of AceCS1 in the rat brain. AceCS1 immunoreactivity in the adult rat brain was present predominantly in cell nuclei, with only light to moderate cytoplasmic staining in some neurons, axons, and oligodendrocytes. Some nonneuronal cell nuclei were very strongly immunoreactive, including those of some oligodendrocytes, whereas neuronal nuclei ranged from unstained to moderately stained. Both antibodies stained some neuronal cell bodies and axons, especially in the hindbrain. AceCS1 immunoreactivity was stronger and more widespread in the brains of 18-day-old rats than in adults, with increased expression in oligodendrocytes and neurons, including cortical pyramidal cells. Expression of AceCS1 was substantially up-regulated in neurons throughout the brain after controlled cortical impact injury. The strong AceCS1 expression observed in the nuclei of CNS cells during brain development and after injury is consistent with a role in nuclear histone acetylation and therefore the regulation of chromatin structure and gene expression. The cytoplasmic staining observed in some oligodendrocytes, especially during postnatal brain development, suggests an additional role in CNS lipid synthesis and myelination. Neuronal and axonal localization implicates AceCS1 in cytoplasmic acetylation reactions in some neurons.
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Affiliation(s)
- Prasanth S Ariyannur
- Department of Anatomy, Molecular and Cell Biology Program and Neuroscience Program, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA
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Rocha LL, Lopez-Meraz ML, Niquet J, Wasterlain CG. Do single seizures cause neuronal death in the human hippocampus? Epilepsy Curr 2010; 7:77-81. [PMID: 17520081 PMCID: PMC1874327 DOI: 10.1111/j.1535-7511.2007.00178.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The question of whether repeated single seizures cause neuronal death in the adult human brain is of great clinical importance and might have broad therapeutic implications. Reviewed here are recent studies on the effects of repeated single seizures (in the absence of status epilepticus) on hippocampal volume and on neuronal death markers in blood and in surgically ablated hippocampi.
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Affiliation(s)
- Luisa L Rocha
- Pharmacobiology Department, Center for Research and Advanced Studies, Mexico City, Mexico
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35
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Ariyannur PS, Moffett JR, Manickam P, Pattabiraman N, Arun P, Nitta A, Nabeshima T, Madhavarao CN, Namboodiri AMA. Methamphetamine-induced neuronal protein NAT8L is the NAA biosynthetic enzyme: implications for specialized acetyl coenzyme A metabolism in the CNS. Brain Res 2010; 1335:1-13. [PMID: 20385109 DOI: 10.1016/j.brainres.2010.04.008] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 02/20/2010] [Accepted: 04/05/2010] [Indexed: 01/12/2023]
Abstract
N-acetylaspartate (NAA) is a concentrated, neuron-specific brain metabolite routinely used as a magnetic resonance spectroscopy marker for brain injury and disease. Despite decades of research, the functional roles of NAA remain unclear. Biochemical investigations over several decades have associated NAA with myelin lipid synthesis and energy metabolism. However, studies have been hampered by an inability to identify the gene for the NAA biosynthetic enzyme aspartate N-acetyltransferase (Asp-NAT). A very recent report has identified Nat8l as the gene encoding Asp-NAT and confirmed that the only child diagnosed with a lack of NAA on brain magnetic resonance spectrograms has a 19-bp deletion in this gene. Based on in vitro Nat8l expression studies the researchers concluded that many previous biochemical investigations have been technically flawed and that NAA may not be associated with brain energy or lipid metabolism. In studies done concurrently in our laboratory we have demonstrated via cloning, expression, specificity for acetylation of aspartate, responsiveness to methamphetamine treatment, molecular modeling and comparative immunolocalization that NAT8L is the NAA biosynthetic enzyme Asp-NAT. We conclude that NAA is a major storage and transport form of acetyl coenzyme A specific to the nervous system, thus linking it to both lipid synthesis and energy metabolism.
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Affiliation(s)
- Prasanth S Ariyannur
- Uniformed Services University of Health Sciences, Department of Anatomy, Physiology and Genetics, Molecular and Cell Biology Program, Neuroscience Program, 4301 Jones Bridge Road, Bldg C, Rm 2069, APG, Bethesda, MD 20814, USA
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Devi L, Anandatheerthavarada HK. Mitochondrial trafficking of APP and alpha synuclein: Relevance to mitochondrial dysfunction in Alzheimer's and Parkinson's diseases. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1802:11-9. [PMID: 19619643 PMCID: PMC2790550 DOI: 10.1016/j.bbadis.2009.07.007] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 07/09/2009] [Indexed: 12/21/2022]
Abstract
Mitochondrial dysfunction is an important intracellular lesion associated with a wide variety of diseases including neurodegenerative disorders. In addition to aging, oxidative stress and mitochondrial DNA mutations, recent studies have implicated a role for the mitochondrial accumulation of proteins such as plasma membrane associated amyloid precursor protein (APP) and cytosolic alpha synuclein in the pathogenesis of mitochondrial dysfunction in Alzheimer's disease (AD) and Parkinson's disease (PD), respectively. Both of these proteins contain cryptic mitochondrial targeting signals, which drive their transport across mitochondria. In general, mitochondrial entry of nuclear coded proteins is assisted by import receptors situated in both outer and inner mitochondrial membranes. A growing number of evidence suggests that APP and alpha synclein interact with import receptors to gain entry into mitochondrial compartment. Additionally, carboxy terminal cleaved product of APP, approximately 4 kDa Abeta, is also transported into mitochondria with the help of mitochondrial outer membrane import receptors. This review focuses on the mitochondrial targeting and accumulation of these two structurally different proteins and the mode of mechanism by which they affect the physiological functions of mitochondria.
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Affiliation(s)
- Latha Devi
- Department of Animal Biology, School of Veterinary Medicine, 3800 Spruce Street, University of Pennsylvania, Philadelphia, PA 19104
| | - Hindupur K. Anandatheerthavarada
- Department of Animal Biology, School of Veterinary Medicine, 3800 Spruce Street, University of Pennsylvania, Philadelphia, PA 19104
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Molecular identification of aspartate N-acetyltransferase and its mutation in hypoacetylaspartia. Biochem J 2009; 425:127-36. [PMID: 19807691 DOI: 10.1042/bj20091024] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The brain-specific compound NAA (N-acetylaspartate) occurs almost exclusively in neurons, where its concentration reaches approx. 20 mM. Its abundance is determined in patients by MRS (magnetic resonance spectroscopy) to assess neuronal density and health. The molecular identity of the NAT (N-acetyltransferase) that catalyses NAA synthesis has remained unknown, because the enzyme is membrane-bound and difficult to purify. Database searches indicated that among putative NATs (i.e. proteins homologous with known NATs, but with uncharacterized catalytic activity) encoded by the human and mouse genomes two were almost exclusively expressed in brain, NAT8L and NAT14. Transfection studies in HEK-293T [human embryonic kidney-293 cells expressing the large T-antigen of SV40 (simian virus 40)] indicated that NAT8L, but not NAT14, catalysed the synthesis of NAA from L-aspartate and acetyl-CoA. The specificity of NAT8L, its Km for aspartate and its sensitivity to detergents are similar to those described for brain Asp-NAT. Confocal microscopy analysis of CHO (Chinese-hamster ovary) cells and neurons expressing recombinant NAT8L indicates that it is associated with the ER (endoplasmic reticulum), but not with mitochondria. A mutation search in the NAT8L gene of the only patient known to be deficient in NAA disclosed the presence of a homozygous 19 bp deletion, resulting in a change in reading frame and the absence of production of a functional protein. We conclude that NAT8L, a neuron-specific protein, is responsible for NAA synthesis and is mutated in primary NAA deficiency (hypoacetylaspartia). The molecular identification of this enzyme will lead to new perspectives in the clarification of the function of this most abundant amino acid derivative in neurons and for the diagnosis of hypoacetylaspartia in other patients.
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Ertugrul A, Volkan-Salanci B, Basar K, Karli Oguz K, Demir B, Ergun EL, Senturk S, Erbas B, Cila A, Ulug B. The effect of clozapine on regional cerebral blood flow and brain metabolite ratios in schizophrenia: relationship with treatment response. Psychiatry Res 2009; 174:121-9. [PMID: 19837567 DOI: 10.1016/j.pscychresns.2009.04.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2007] [Revised: 01/13/2009] [Accepted: 04/15/2009] [Indexed: 10/20/2022]
Abstract
The purpose of this study was to investigate the effect of clozapine on regional cerebral blood flow (rCBF) and its relationship with response to treatment. In addition, we aimed to study the influence of clozapine on proton magnetic resonance spectroscopy ((1)H-MRS) findings in the dorsolateral prefrontal cortex (DLPFC) in a subgroup of patients. Psychopathology, neurocognitive functioning, and SPECT imaging of 22 patients were assessed at the baseline and 8 weeks after the initiation of clozapine treatment. In 10 of these patients intermediate-echo (TE: 135 ms) single-voxel (1)H-MRS was also performed at the baseline and after 8 weeks. Clozapine treatment increased the right frontal (superior and medial)/caudate perfusion ratio in the whole group, while it increased bilateral frontal (superior and medial)/caudate perfusion ratios in treatment responders. In addition, percentage changes in left and right frontal (superior and medial)/caudate perfusion ratios compared to the baseline were higher in treatment responders than in non-responders. The improvement in attention was related to the increase in percentage change in the right frontal (superior and medial)/caudate perfusion ratio, while the improvement in verbal fluency was related to the increase in percentage changes in both right and left frontal (superior and medial)/caudate perfusion ratios and to right frontal (superior and medial)/thalamus perfusion. Baseline frontal (superior and medial)/thalamus perfusion could explain 32% of the variability of percentage improvements in psychopathology. (1)H-MRS showed that the baseline PANSS general psychopathology score was inversely correlated with the baseline NAA/Cre ratio. An increased NAA/Cre ratio in DLPFC after 8 weeks of clozapine treatment was also revealed by (1)H-MRS. Our SPECT imaging results suggest the presence of an imbalance in fronto-striato-thalamic circuitry that changes with clozapine, especially in the responders, while (1)H-MRS results indicate a supportive effect of clozapine on neuronal integrity.
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Affiliation(s)
- Aygun Ertugrul
- Hacettepe University, Faculty of Medicine, Department of Psychiatry, Ankara, Turkey.
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Evidence for mitochondrial and cytoplasmic N-acetylaspartate synthesis in SH-SY5Y neuroblastoma cells. Neurochem Int 2009; 55:219-25. [DOI: 10.1016/j.neuint.2009.03.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Revised: 02/17/2009] [Accepted: 03/03/2009] [Indexed: 11/21/2022]
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Su KG, Banker G, Bourdette D, Forte M. Axonal degeneration in multiple sclerosis: the mitochondrial hypothesis. Curr Neurol Neurosci Rep 2009; 9:411-7. [PMID: 19664372 DOI: 10.1007/s11910-009-0060-3] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Multiple sclerosis (MS) is a chronic disease of the central nervous system, affecting more than 2 million people worldwide. Traditionally considered an inflammatory demyelinating disease, recent evidence now points to axonal degeneration as crucial to the development of irreversible disability. Studies show that axonal degeneration occurs throughout the entire course of MS. Although the specific mechanisms causing axonal damage may differ at various stages, mitochondrial failure seems to be a common underlying theme. This review addresses the mitochondrial hypothesis for axonal degeneration in MS, highlighting the mechanisms by which mitochondrial dysfunction leads to axonal disruption in acute inflammatory lesions and the chronic axonopathy in progressive MS. Emphasis is placed on Ca(2+), free radical production, and permeability transition pore opening as key players in mitochondrial failure, axonal transport impairment, and subsequent axonal degeneration. In addition, the role of mitochondria as therapeutic targets for neuroprotection in MS is addressed.
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Affiliation(s)
- Kimmy G Su
- Oregon Health & Science University, Vollum Institute, L474, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA.
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41
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Mutagenicity studies with N-acetyl-l-aspartic acid. Food Chem Toxicol 2009; 47:1936-40. [DOI: 10.1016/j.fct.2009.05.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 05/06/2009] [Accepted: 05/07/2009] [Indexed: 11/21/2022]
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Wibom R, Lasorsa FM, Töhönen V, Barbaro M, Sterky FH, Kucinski T, Naess K, Jonsson M, Pierri CL, Palmieri F, Wedell A. AGC1 deficiency associated with global cerebral hypomyelination. N Engl J Med 2009; 361:489-95. [PMID: 19641205 DOI: 10.1056/nejmoa0900591] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mitochondrial aspartate-glutamate carrier isoform 1 (AGC1), specific to neurons and muscle, supplies aspartate to the cytosol and, as a component of the malate-aspartate shuttle, enables mitochondrial oxidation of cytosolic NADH, thought to be important in providing energy for neurons in the central nervous system. We describe AGC1 deficiency, a novel syndrome characterized by arrested psychomotor development, hypotonia, and seizures in a child with a homozygous missense mutation in the solute carrier family 25, member 12, gene SLC25A12, which encodes the AGC1 protein. Functional analysis of the mutant AGC1 protein showed abolished activity. The child had global hypomyelination in the cerebral hemispheres, suggesting that impaired efflux of aspartate from neuronal mitochondria prevents normal myelin formation.
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Affiliation(s)
- Rolf Wibom
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
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Neuroimaging studies of normal brain development and their relevance for understanding childhood neuropsychiatric disorders. J Am Acad Child Adolesc Psychiatry 2008; 47:1233-51. [PMID: 18833009 PMCID: PMC2759682 DOI: 10.1097/chi.0b013e318185e703] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To review the maturational events that occur during prenatal and postnatal brain development and to present neuroimaging findings from studies of healthy individuals that identify the trajectories of normal brain development. METHOD Histological and postmortem findings of early brain development are presented, followed by a discussion of anatomical, diffusion tensor, proton spectroscopy, and functional imaging findings from studies of healthy individuals, with special emphasis on longitudinal data. RESULTS Early brain development occurs through a sequence of major events, beginning with the formation of the neural tube and ending with myelination. Brain development at a macroscopic level typically proceeds first in sensorimotor areas, spreading subsequently and progressively into dorsal and parietal, superior temporal, and dorsolateral prefrontal cortices throughout later childhood and adolescence. These patterns of anatomical development parallel increasing activity in frontal cortices that subserves the development of higher-order cognitive functions during late childhood and adolescence. Disturbances in these developmental patterns seem to be involved centrally in the pathogenesis of various childhood psychiatric disorders including childhood-onset schizophrenia, attention-deficit/hyperactivity disorder, developmental dyslexia, Tourette's syndrome, and bipolar disorder. CONCLUSIONS Advances in imaging techniques have enhanced our understanding of normal developmental trajectories in the brain, which may improve insight into the abnormal patterns of development in various childhood psychiatric disorders.
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Ariyannur PS, Madhavarao CN, Namboodiri AMA. N-acetylaspartate synthesis in the brain: mitochondria vs. microsomes. Brain Res 2008; 1227:34-41. [PMID: 18621030 DOI: 10.1016/j.brainres.2008.06.040] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 06/09/2008] [Accepted: 06/14/2008] [Indexed: 10/21/2022]
Abstract
Several reports during the last three decades have indicated that biosynthesis of N-acetylaspartate (NAA) occurs primarily in the mitochondria. But a recent report by Lu et al. in this journal [2004; 122: 71-78] and subsequent two reports that cited those data suggested a predominant microsomal localization of the NAA biosynthetic enzyme, which is surprising in view of what is known about the biological functions of NAA. Therefore we reinvestigated this issue in rat brain homogenates using a similar fractionation procedure used by Lu et al. but without the loss of enzyme activity that they have encountered. We found that about 70% of the total Asp-NAT activity in the crude supernatant was present in the mitochondrial fraction which is about 5 times more than that in the microsomes. We found similar results in the case of the enzyme from bovine brain. In subsequent studies, we also have found that Asp-NAT activity in the bovine brain is very similar to that in the rat brain in substrate specificity and chromatographic characteristics including the high molecular weight pattern (approx. 670 kD) on size-exclusion HPLC.
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Affiliation(s)
- Prasanth S Ariyannur
- Rm. C 2069, Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
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Satrústegui J, Contreras L, Ramos M, Marmol P, del Arco A, Saheki T, Pardo B. Role of aralar, the mitochondrial transporter of aspartate-glutamate, in brain N-acetylaspartate formation and Ca(2+) signaling in neuronal mitochondria. J Neurosci Res 2008; 85:3359-66. [PMID: 17497669 DOI: 10.1002/jnr.21299] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Aralar, the Ca(2+)-dependent mitochondrial aspartate-glutamate carrier expressed in brain and skeletal muscle, is a member of the malate-aspartate NADH shuttle. Disrupting the gene for aralar, SLC25a12, in mice has enabled the discovery of two new roles of this carrier. On the one hand, it is required for synthesis of brain aspartate and N-acetylaspartate, a neuron-born metabolite that supplies acetate for myelin lipid synthesis; and on the other, it is essential for the transmission of small Ca(2+) signals to mitochondria via an increase in mitochondrial NADH.
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Affiliation(s)
- Jorgina Satrústegui
- Departamento de Biología Molecular, Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Universidad Autónoma, 28049, Cantoblanco, Madrid, Spain
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Tang CY, Friedman J, Shungu D, Chang L, Ernst T, Stewart D, Hajianpour A, Carpenter D, Ng J, Mao X, Hof PR, Buchsbaum MS, Davis K, Gorman JM. Correlations between Diffusion Tensor Imaging (DTI) and Magnetic Resonance Spectroscopy (1H MRS) in schizophrenic patients and normal controls. BMC Psychiatry 2007; 7:25. [PMID: 17578565 PMCID: PMC1929081 DOI: 10.1186/1471-244x-7-25] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Accepted: 06/19/2007] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Evidence suggests that white matter integrity may play an underlying pathophysiological role in schizophrenia. N-acetylaspartate (NAA), as measured by Magnetic Resonance Spectroscopy (MRS), is a neuronal marker and is decreased in white matter lesions and regions of axonal loss. It has also been found to be reduced in the prefrontal and temporal regions in patients with schizophrenia. Diffusion Tensor Imaging (DTI) allows one to measure the orientations of axonal tracts as well as the coherence of axonal bundles. DTI is thus sensitive to demyelination and other structural abnormalities. DTI has also shown abnormalities in these regions. METHODS MRS and DTI were obtained on 42 healthy subjects and 40 subjects with schizophrenia. The data was analyzed using regions of interests in the Dorso-Lateral Prefrontal white matter, Medial Temporal white matter and Occipital white matter using both imaging modalities. RESULTS NAA was significantly reduced in the patient population in the Medial Temporal regions. DTI anisotropy indices were also reduced in the same Medial Temporal regions. NAA and DTI-anisotropy indices were also correlated in the left medial temporal region. CONCLUSION Our results implicate defects in the medial temporal white matter in patients with schizophrenia. Moreover, MRS and DTI are complementary modalities for the study of white matter disruptions in patients with schizophrenia.
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Affiliation(s)
- Cheuk Y Tang
- Department of Radiology, Mount Sinai School of Medicine NY, NY 10029, USA
- Department of Psychiatry, Mount Sinai School of Medicine NY, NY 10029, USA
- Department of Pathology, Mount Sinai School of Medicine NY, NY 10029, USA
| | - Joseph Friedman
- Department of Psychiatry, Mount Sinai School of Medicine NY, NY 10029, USA
| | - Dikoma Shungu
- Department of Radiology, Weill Medical College of Cornell University, NY, NY 10021, USA
| | - Linda Chang
- Department of Medicine, University of Hawaii, HI 96817, USA
| | - Thomas Ernst
- Department of Medicine, University of Hawaii, HI 96817, USA
| | - Daniel Stewart
- Department of Psychiatry, Mount Sinai School of Medicine NY, NY 10029, USA
| | - Arash Hajianpour
- Department of Radiology, Mount Sinai School of Medicine NY, NY 10029, USA
| | - David Carpenter
- Department of Radiology, Mount Sinai School of Medicine NY, NY 10029, USA
| | - Johnny Ng
- Department of Radiology, Mount Sinai School of Medicine NY, NY 10029, USA
| | - Xiangling Mao
- Department of Radiology, Weill Medical College of Cornell University, NY, NY 10021, USA
| | - Patrick R Hof
- Department of Neuroscience, Mount Sinai School of Medicine NY, NY 10029, USA
| | - Monte S Buchsbaum
- Department of Psychiatry, Mount Sinai School of Medicine NY, NY 10029, USA
| | - Kenneth Davis
- Department of Psychiatry, Mount Sinai School of Medicine NY, NY 10029, USA
| | - Jack M Gorman
- Department of Psychiatry, Mount Sinai School of Medicine NY, NY 10029, USA
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Wang J, Matalon R, Bhatia G, Wu G, Li H, Liu T, Lu ZH, Ledeen RW. Bimodal occurrence of aspartoacylase in myelin and cytosol of brain. J Neurochem 2007; 101:448-57. [PMID: 17254025 DOI: 10.1111/j.1471-4159.2006.04380.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The growing use of N-acetylaspartate as an indicator of neuronal viability has fostered interest in the biological function(s) of this unusual amino acid derivative. In considering the various physiological roles that have been proposed for this relatively abundant molecule one is obliged to take into account its unusual metabolic compartmentalization, according to which synthesis and storage occur in the neuron and hydrolytic cleavage in the oligodendrocyte. The latter reaction, catalyzed by aspartoacylase (ASPA), produces acetyl groups plus aspartate and has been proposed to occur in both soluble and membranous subfractions of white matter. Our study supports such bimodal occurrence and we now present immunoblot, proteomic, and biochemical evidence that the membrane-bound form of ASPA is intrinsic to purified myelin membranes. This was supported by a novel TLC-based method for the assay of ASPA. That observation, together with previous demonstrations of numerous lipid-synthesizing enzymes in myelin, suggests utilization of acetyl groups liberated by myelin-localized ASPA for lipid synthesis within the myelin sheath. Such synthesis might be selective and could explain the deficit of myelin lipids in animals lacking ASPA.
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Affiliation(s)
- Jianfeng Wang
- Department of Neurology and Neurosciences, New Jersey Medical School, UMDNJ, Newark, New Jersey 07103, USA
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Tranberg M, Sandberg M. N-acetylaspartate monomethyl ester increases N-acetylaspartate concentration in cultured rat hippocampal slices: effects on excitotoxicity and levels of amino acids and chloride. J Neurosci Methods 2007; 163:105-10. [PMID: 17386946 DOI: 10.1016/j.jneumeth.2007.02.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2006] [Revised: 01/22/2007] [Accepted: 02/18/2007] [Indexed: 11/17/2022]
Abstract
N-acetylaspartate (NAA) was discovered in mammalian brain 50 years ago but its functions remain debated. One reason for the relatively slow progress of NAA research is the paucity of tools to specifically modify NAA concentrations. In this work we evaluated the use of the monomethyl ester of NAA (NAA MME) to increase the relatively low level of NAA in cultured hippocampal slices. When slices were treated with 30 mM NAA MME for 3 days the NAA concentration increased from 31.6 to 185.3 nmol/mg protein. Incubation with NAA alone increased the NAA concentration non-significantly to 65.6 nmol/mg protein. NAA MME treatment increased NAA in neurons and the increase was non-toxic as determined by the low uptake of propidium iodide, a dye that only enters damaged cells. NMDA-mediated excitotoxicity which is initiated by influx of Ca(2+) was unaltered by increased NAA levels indicating poor intracellular Ca(2+)-chelation by NAA.
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Affiliation(s)
- Mattias Tranberg
- Institute of Neuroscience and Physiology, Department of Physiology, Göteborg University, Göteborg, Sweden.
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Moffett JR, Ross B, Arun P, Madhavarao CN, Namboodiri AMA. N-Acetylaspartate in the CNS: from neurodiagnostics to neurobiology. Prog Neurobiol 2007; 81:89-131. [PMID: 17275978 PMCID: PMC1919520 DOI: 10.1016/j.pneurobio.2006.12.003] [Citation(s) in RCA: 977] [Impact Index Per Article: 57.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Revised: 12/07/2006] [Accepted: 12/11/2006] [Indexed: 01/02/2023]
Abstract
The brain is unique among organs in many respects, including its mechanisms of lipid synthesis and energy production. The nervous system-specific metabolite N-acetylaspartate (NAA), which is synthesized from aspartate and acetyl-coenzyme A in neurons, appears to be a key link in these distinct biochemical features of CNS metabolism. During early postnatal central nervous system (CNS) development, the expression of lipogenic enzymes in oligodendrocytes, including the NAA-degrading enzyme aspartoacylase (ASPA), is increased along with increased NAA production in neurons. NAA is transported from neurons to the cytoplasm of oligodendrocytes, where ASPA cleaves the acetate moiety for use in fatty acid and steroid synthesis. The fatty acids and steroids produced then go on to be used as building blocks for myelin lipid synthesis. Mutations in the gene for ASPA result in the fatal leukodystrophy Canavan disease, for which there is currently no effective treatment. Once postnatal myelination is completed, NAA may continue to be involved in myelin lipid turnover in adults, but it also appears to adopt other roles, including a bioenergetic role in neuronal mitochondria. NAA and ATP metabolism appear to be linked indirectly, whereby acetylation of aspartate may facilitate its removal from neuronal mitochondria, thus favoring conversion of glutamate to alpha ketoglutarate which can enter the tricarboxylic acid cycle for energy production. In its role as a mechanism for enhancing mitochondrial energy production from glutamate, NAA is in a key position to act as a magnetic resonance spectroscopy marker for neuronal health, viability and number. Evidence suggests that NAA is a direct precursor for the enzymatic synthesis of the neuron specific dipeptide N-acetylaspartylglutamate, the most concentrated neuropeptide in the human brain. Other proposed roles for NAA include neuronal osmoregulation and axon-glial signaling. We propose that NAA may also be involved in brain nitrogen balance. Further research will be required to more fully understand the biochemical functions served by NAA in CNS development and activity, and additional functions are likely to be discovered.
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Affiliation(s)
- John R Moffett
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Building C, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA.
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Satrústegui J, Pardo B, Del Arco A. Mitochondrial Transporters as Novel Targets for Intracellular Calcium Signaling. Physiol Rev 2007; 87:29-67. [PMID: 17237342 DOI: 10.1152/physrev.00005.2006] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ca2+signaling in mitochondria is important to tune mitochondrial function to a variety of extracellular stimuli. The main mechanism is Ca2+entry in mitochondria via the Ca2+uniporter followed by Ca2+activation of three dehydrogenases in the mitochondrial matrix. This results in increases in mitochondrial NADH/NAD ratios and ATP levels and increased substrate uptake by mitochondria. We review evidence gathered more than 20 years ago and recent work indicating that substrate uptake, mitochondrial NADH/NAD ratios, and ATP levels may be also activated in response to cytosolic Ca2+signals via a mechanism that does not require the entry of Ca2+in mitochondria, a mechanism depending on the activity of Ca2+-dependent mitochondrial carriers (CaMC). CaMCs fall into two groups, the aspartate-glutamate carriers (AGC) and the ATP-Mg/Picarriers, also named SCaMC (for short CaMC). The two mammalian AGCs, aralar and citrin, are members of the malate-aspartate NADH shuttle, and citrin, the liver AGC, is also a member of the urea cycle. Both types of CaMCs are activated by Ca2+in the intermembrane space and function together with the Ca2+uniporter in decoding the Ca2+signal into a mitochondrial response.
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Affiliation(s)
- Jorgina Satrústegui
- Departamento de Biología Molecular Centro de Biología Molecular "Severo Ochoa" UAM-CSIC, Facultad de Ciencias, Universidad Autónoma, Madrid, Spain.
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