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Andersen JV, Schousboe A. Glial Glutamine Homeostasis in Health and Disease. Neurochem Res 2023; 48:1100-1128. [PMID: 36322369 DOI: 10.1007/s11064-022-03771-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 08/25/2022] [Accepted: 09/27/2022] [Indexed: 11/05/2022]
Abstract
Glutamine is an essential cerebral metabolite. Several critical brain processes are directly linked to glutamine, including ammonia homeostasis, energy metabolism and neurotransmitter recycling. Astrocytes synthesize and release large quantities of glutamine, which is taken up by neurons to replenish the glutamate and GABA neurotransmitter pools. Astrocyte glutamine hereby sustains the glutamate/GABA-glutamine cycle, synaptic transmission and general brain function. Cerebral glutamine homeostasis is linked to the metabolic coupling of neurons and astrocytes, and relies on multiple cellular processes, including TCA cycle function, synaptic transmission and neurotransmitter uptake. Dysregulations of processes related to glutamine homeostasis are associated with several neurological diseases and may mediate excitotoxicity and neurodegeneration. In particular, diminished astrocyte glutamine synthesis is a common neuropathological component, depriving neurons of an essential metabolic substrate and precursor for neurotransmitter synthesis, hereby leading to synaptic dysfunction. While astrocyte glutamine synthesis is quantitatively dominant in the brain, oligodendrocyte-derived glutamine may serve important functions in white matter structures. In this review, the crucial roles of glial glutamine homeostasis in the healthy and diseased brain are discussed. First, we provide an overview of cellular recycling, transport, synthesis and metabolism of glutamine in the brain. These cellular aspects are subsequently discussed in relation to pathological glutamine homeostasis of hepatic encephalopathy, epilepsy, Alzheimer's disease, Huntington's disease and amyotrophic lateral sclerosis. Further studies on the multifaceted roles of cerebral glutamine will not only increase our understanding of the metabolic collaboration between brain cells, but may also aid to reveal much needed therapeutic targets of several neurological pathologies.
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Affiliation(s)
- Jens V Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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2
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Yin C, Harms AC, Hankemeier T, Kindt A, de Lange ECM. Status of Metabolomic Measurement for Insights in Alzheimer's Disease Progression-What Is Missing? Int J Mol Sci 2023; 24:ijms24054960. [PMID: 36902391 PMCID: PMC10003384 DOI: 10.3390/ijms24054960] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/24/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Alzheimer's disease (AD) is an aging-related neurodegenerative disease, leading to the progressive loss of memory and other cognitive functions. As there is still no cure for AD, the growth in the number of susceptible individuals represents a major emerging threat to public health. Currently, the pathogenesis and etiology of AD remain poorly understood, while no efficient treatments are available to slow down the degenerative effects of AD. Metabolomics allows the study of biochemical alterations in pathological processes which may be involved in AD progression and to discover new therapeutic targets. In this review, we summarized and analyzed the results from studies on metabolomics analysis performed in biological samples of AD subjects and AD animal models. Then this information was analyzed by using MetaboAnalyst to find the disturbed pathways among different sample types in human and animal models at different disease stages. We discuss the underlying biochemical mechanisms involved, and the extent to which they could impact the specific hallmarks of AD. Then we identify gaps and challenges and provide recommendations for future metabolomics approaches to better understand AD pathogenesis.
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Affiliation(s)
- Chunyuan Yin
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
- Division of Systems Pharmacology and Pharmacy, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
| | - Amy C. Harms
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
| | - Thomas Hankemeier
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
| | - Alida Kindt
- Metabolomics and Analytics Centre, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
| | - Elizabeth C. M. de Lange
- Division of Systems Pharmacology and Pharmacy, Leiden Academic Centre for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands
- Correspondence:
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3
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Strefeler A, Jan M, Quadroni M, Teav T, Rosenberg N, Chatton JY, Guex N, Gallart-Ayala H, Ivanisevic J. Molecular insights into sex-specific metabolic alterations in Alzheimer's mouse brain using multi-omics approach. Alzheimers Res Ther 2023; 15:8. [PMID: 36624525 PMCID: PMC9827669 DOI: 10.1186/s13195-023-01162-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 01/02/2023] [Indexed: 01/11/2023]
Abstract
BACKGROUND Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is characterized by altered cellular metabolism in the brain. Several of these alterations have been found to be exacerbated in females, known to be disproportionately affected by AD. We aimed to unravel metabolic alterations in AD at the metabolic pathway level and evaluate whether they are sex-specific through integrative metabolomic, lipidomic, and proteomic analysis of mouse brain tissue. METHODS We analyzed male and female triple-transgenic mouse whole brain tissue by untargeted mass spectrometry-based methods to obtain a molecular signature consisting of polar metabolite, complex lipid, and protein data. These data were analyzed using multi-omics factor analysis. Pathway-level alterations were identified through joint pathway enrichment analysis or by separately evaluating lipid ontology and known proteins related to lipid metabolism. RESULTS Our analysis revealed significant AD-associated and in part sex-specific alterations across the molecular signature. Sex-dependent alterations were identified in GABA synthesis, arginine biosynthesis, and in alanine, aspartate, and glutamate metabolism. AD-associated alterations involving lipids were also found in the fatty acid elongation pathway and lysophospholipid metabolism, with a significant sex-specific effect for the latter. CONCLUSIONS Through multi-omics analysis, we report AD-associated and sex-specific metabolic alterations in the AD brain involving lysophospholipid and amino acid metabolism. These findings contribute to the characterization of the AD phenotype at the molecular level while considering the effect of sex, an overlooked yet determinant metabolic variable.
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Affiliation(s)
- Abigail Strefeler
- grid.9851.50000 0001 2165 4204Metabolomics Unit, Faculty of Biology and Medicine, University de Lausanne, Lausanne, Switzerland
| | - Maxime Jan
- grid.9851.50000 0001 2165 4204Bioinformatics Competence Center, Faculty of Biology and Medicine, University de Lausanne, Lausanne, Switzerland
| | - Manfredo Quadroni
- grid.9851.50000 0001 2165 4204Protein Analysis Facility, Faculty of Biology and Medicine, University de Lausanne, Lausanne, Switzerland
| | - Tony Teav
- grid.9851.50000 0001 2165 4204Metabolomics Unit, Faculty of Biology and Medicine, University de Lausanne, Lausanne, Switzerland
| | - Nadia Rosenberg
- grid.9851.50000 0001 2165 4204Department of Fundamental Neurosciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Jean-Yves Chatton
- grid.9851.50000 0001 2165 4204Department of Fundamental Neurosciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Guex
- grid.9851.50000 0001 2165 4204Bioinformatics Competence Center, Faculty of Biology and Medicine, University de Lausanne, Lausanne, Switzerland
| | - Hector Gallart-Ayala
- grid.9851.50000 0001 2165 4204Metabolomics Unit, Faculty of Biology and Medicine, University de Lausanne, Lausanne, Switzerland
| | - Julijana Ivanisevic
- grid.9851.50000 0001 2165 4204Metabolomics Unit, Faculty of Biology and Medicine, University de Lausanne, Lausanne, Switzerland
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4
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Xu QA, Boerkoel P, Hirsch-Reinshagen V, Mackenzie IR, Hsiung GYR, Charm G, To EF, Liu AQ, Schwab K, Jiang K, Sarunic M, Beg MF, Pham W, Cui J, To E, Lee S, Matsubara JA. Müller cell degeneration and microglial dysfunction in the Alzheimer's retina. Acta Neuropathol Commun 2022; 10:145. [PMID: 36199154 PMCID: PMC9533552 DOI: 10.1186/s40478-022-01448-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 09/18/2022] [Indexed: 01/26/2023] Open
Abstract
Amyloid beta (Aβ) deposits in the retina of the Alzheimer's disease (AD) eye may provide a useful diagnostic biomarker for AD. This study focused on the relationship of Aβ with macroglia and microglia, as these glial cells are hypothesized to play important roles in homeostasis and clearance of Aβ in the AD retina. Significantly higher Aβ load was found in AD compared to controls, and specifically in the mid-peripheral region. AD retina showed significantly less immunoreactivity against glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS) compared to control eyes. Immunoreactivity against ionized calcium binding adapter molecule-1 (IBA-1), a microglial marker, demonstrated a higher level of microgliosis in AD compared to control retina. Within AD retina, more IBA-1 immunoreactivity was present in the mid-peripheral retina, which contained more Aβ than the central AD retina. GFAP co-localized rarely with Aβ, while IBA-1 co-localized with Aβ in more layers of control than AD donor retina. These results suggest that dysfunction of the Müller and microglial cells may be key features of the AD retina.
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Affiliation(s)
- Qinyuan Alis Xu
- grid.17091.3e0000 0001 2288 9830MD Undergraduate Program, University of British Columbia, Vancouver, BC Canada ,grid.17063.330000 0001 2157 2938Postgraduate Medical Education, Department of Family and Community Medicine, University of Toronto, Barrie, ON Canada
| | - Pierre Boerkoel
- grid.17091.3e0000 0001 2288 9830MD Undergraduate Program, University of British Columbia, Vancouver, BC Canada
| | - Veronica Hirsch-Reinshagen
- grid.17091.3e0000 0001 2288 9830Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC Canada
| | - Ian R. Mackenzie
- grid.17091.3e0000 0001 2288 9830Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC Canada
| | - Ging-Yuek Robin Hsiung
- grid.17091.3e0000 0001 2288 9830Division of Neurology, Department of Medicine, University of British Columbia, Vancouver, BC Canada
| | - Geoffrey Charm
- grid.17091.3e0000 0001 2288 9830Department of Ophthalmology and Visual Sciences, Eye Care Centre, University of British Columbia, 2550 Willow Street, Vancouver, BC V5Z3N9 Canada
| | - Elliott F. To
- grid.17091.3e0000 0001 2288 9830Department of Ophthalmology and Visual Sciences, Eye Care Centre, University of British Columbia, 2550 Willow Street, Vancouver, BC V5Z3N9 Canada
| | - Alice Q. Liu
- grid.17091.3e0000 0001 2288 9830MD Undergraduate Program, University of British Columbia, Vancouver, BC Canada
| | - Katerina Schwab
- grid.17091.3e0000 0001 2288 9830MD Undergraduate Program, University of British Columbia, Vancouver, BC Canada
| | - Kailun Jiang
- grid.17091.3e0000 0001 2288 9830Department of Ophthalmology and Visual Sciences, Eye Care Centre, University of British Columbia, 2550 Willow Street, Vancouver, BC V5Z3N9 Canada
| | - Marinko Sarunic
- grid.61971.380000 0004 1936 7494School of Engineering Sciences, Simon Fraser University, Burnaby, BC Canada
| | - Mirza Faisal Beg
- grid.61971.380000 0004 1936 7494School of Engineering Sciences, Simon Fraser University, Burnaby, BC Canada
| | - Wellington Pham
- grid.152326.10000 0001 2264 7217Vanderbilt University Institute of Imaging Science, Vanderbilt University School of Medicine, Nashville, USA
| | - Jing Cui
- grid.17091.3e0000 0001 2288 9830Department of Ophthalmology and Visual Sciences, Eye Care Centre, University of British Columbia, 2550 Willow Street, Vancouver, BC V5Z3N9 Canada
| | - Eleanor To
- grid.17091.3e0000 0001 2288 9830Department of Ophthalmology and Visual Sciences, Eye Care Centre, University of British Columbia, 2550 Willow Street, Vancouver, BC V5Z3N9 Canada
| | - Sieun Lee
- grid.61971.380000 0004 1936 7494School of Engineering Sciences, Simon Fraser University, Burnaby, BC Canada ,grid.4563.40000 0004 1936 8868Mental Health & Clinical Neurosciences, School of Medicine, University of Nottingham, University of Nottingham, Nottingham, England
| | - Joanne A. Matsubara
- grid.17091.3e0000 0001 2288 9830Department of Ophthalmology and Visual Sciences, Eye Care Centre, University of British Columbia, 2550 Willow Street, Vancouver, BC V5Z3N9 Canada
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Garland EF, Hartnell IJ, Boche D. Microglia and Astrocyte Function and Communication: What Do We Know in Humans? Front Neurosci 2022; 16:824888. [PMID: 35250459 PMCID: PMC8888691 DOI: 10.3389/fnins.2022.824888] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 01/24/2022] [Indexed: 12/11/2022] Open
Abstract
Microglia and astrocytes play essential roles in the central nervous system contributing to many functions including homeostasis, immune response, blood–brain barrier maintenance and synaptic support. Evidence has emerged from experimental models of glial communication that microglia and astrocytes influence and coordinate each other and their effects on the brain environment. However, due to the difference in glial cells between humans and rodents, it is essential to confirm the relevance of these findings in human brains. Here, we aim to review the current knowledge on microglia-astrocyte crosstalk in humans, exploring novel methodological techniques used in health and disease conditions. This will include an in-depth look at cell culture and iPSCs, post-mortem studies, imaging and fluid biomarkers, genetics and transcriptomic data. In this review, we will discuss the advantages and limitations of these methods, highlighting the understanding these methods have brought the field on these cells communicative abilities, and the knowledge gaps that remain.
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6
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Karaboğa MNS, Sezgintürk MK. Biosensor approaches on the diagnosis of neurodegenerative diseases: Sensing the past to the future. J Pharm Biomed Anal 2022; 209:114479. [PMID: 34861607 DOI: 10.1016/j.jpba.2021.114479] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 11/05/2021] [Accepted: 11/14/2021] [Indexed: 12/12/2022]
Abstract
Early diagnosis of neurodegeneration-oriented diseases that develop with the aging world is essential for improving the patient's living conditions as well as the treatment of the disease. Alzheimer's and Parkinson's diseases are prominent examples of neurodegeneration characterized by dementia leading to the death of nerve cells. The clinical diagnosis of these diseases only after the symptoms appear, delays the treatment process. Detection of biomarkers, which are distinctive molecules in biological fluids, involved in neurodegeneration processes, has the potential to allow early diagnosis of neurodegenerative diseases. Studies on biosensors, whose main responsibility is to detect the target analyte with high specificity, has gained momentum in recent years with the aim of high detection of potential biomarkers of neurodegeneration process. This study aims to provide an overview of neuro-biosensors developed on the basis of biomarkers identified in biological fluids for the diagnosis of neurodegenerative diseases such as Alzheimer's disease (AD), and Parkinson's disease (PD), and to provide an overview of the urgent needs in this field, emphasizing the importance of early diagnosis in the general lines of the neurodegeneration pathway. In this review, biosensor systems developed for the detection of biomarkers of neurodegenerative diseases, especially in the last 5 years, are discussed.
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7
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Viejo L, Noori A, Merrill E, Das S, Hyman BT, Serrano-Pozo A. Systematic review of human post-mortem immunohistochemical studies and bioinformatics analyses unveil the complexity of astrocyte reaction in Alzheimer's disease. Neuropathol Appl Neurobiol 2021; 48:e12753. [PMID: 34297416 PMCID: PMC8766893 DOI: 10.1111/nan.12753] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/29/2021] [Accepted: 07/12/2021] [Indexed: 12/24/2022]
Abstract
AIMS Reactive astrocytes in Alzheimer's disease (AD) have traditionally been demonstrated by increased glial fibrillary acidic protein (GFAP) immunoreactivity; however, astrocyte reaction is a complex and heterogeneous phenomenon involving multiple astrocyte functions beyond cytoskeletal remodelling. To better understand astrocyte reaction in AD, we conducted a systematic review of astrocyte immunohistochemical studies in post-mortem AD brains followed by bioinformatics analyses on the extracted reactive astrocyte markers. METHODS NCBI PubMed, APA PsycInfo and WoS-SCIE databases were interrogated for original English research articles with the search terms 'Alzheimer's disease' AND 'astrocytes.' Bioinformatics analyses included protein-protein interaction network analysis, pathway enrichment, and transcription factor enrichment, as well as comparison with public human -omics datasets. RESULTS A total of 306 articles meeting eligibility criteria rendered 196 proteins, most of which were reported to be upregulated in AD vs control brains. Besides cytoskeletal remodelling (e.g., GFAP), bioinformatics analyses revealed a wide range of functional alterations including neuroinflammation (e.g., IL6, MAPK1/3/8 and TNF), oxidative stress and antioxidant defence (e.g., MT1A/2A, NFE2L2, NOS1/2/3, PRDX6 and SOD1/2), lipid metabolism (e.g., APOE, CLU and LRP1), proteostasis (e.g., cathepsins, CRYAB and HSPB1/2/6/8), extracellular matrix organisation (e.g., CD44, MMP1/3 and SERPINA3), and neurotransmission (e.g., CHRNA7, GABA, GLUL, GRM5, MAOB and SLC1A2), among others. CTCF and ESR1 emerged as potential transcription factors driving these changes. Comparison with published -omics datasets validated our results, demonstrating a significant overlap with reported transcriptomic and proteomic changes in AD brains and/or CSF. CONCLUSIONS Our systematic review of the neuropathological literature reveals the complexity of AD reactive astrogliosis. We have shared these findings as an online resource available at www.astrocyteatlas.org.
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Affiliation(s)
- Lucía Viejo
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.,MassGeneral Institute for Neurodegenerative Disease (MIND), Charlestown, MA, USA.,Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain
| | - Ayush Noori
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.,MassGeneral Institute for Neurodegenerative Disease (MIND), Charlestown, MA, USA.,Harvard College, Cambridge, MA, USA.,MIND Data Science Lab, Cambridge, MA, USA.,Massachusetts Alzheimer's Disease Research Center, Charlestown, MA, USA
| | - Emily Merrill
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.,MassGeneral Institute for Neurodegenerative Disease (MIND), Charlestown, MA, USA.,MIND Data Science Lab, Cambridge, MA, USA
| | - Sudeshna Das
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.,MassGeneral Institute for Neurodegenerative Disease (MIND), Charlestown, MA, USA.,MIND Data Science Lab, Cambridge, MA, USA.,Massachusetts Alzheimer's Disease Research Center, Charlestown, MA, USA.,Harvard Medical School, Harvard University, Boston, MA, USA
| | - Bradley T Hyman
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.,MassGeneral Institute for Neurodegenerative Disease (MIND), Charlestown, MA, USA.,Massachusetts Alzheimer's Disease Research Center, Charlestown, MA, USA.,Harvard Medical School, Harvard University, Boston, MA, USA
| | - Alberto Serrano-Pozo
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.,MassGeneral Institute for Neurodegenerative Disease (MIND), Charlestown, MA, USA.,Massachusetts Alzheimer's Disease Research Center, Charlestown, MA, USA.,Harvard Medical School, Harvard University, Boston, MA, USA
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8
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High performance liquid chromatography determination of L-glutamate, L-glutamine and glycine content in brain, cerebrospinal fluid and blood serum of patients affected by Alzheimer's disease. Amino Acids 2021; 53:435-449. [PMID: 33616735 DOI: 10.1007/s00726-021-02943-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 01/16/2021] [Indexed: 12/30/2022]
Abstract
Altered glutamatergic neurotransmission is thought to play a crucial role in the progression of Alzheimer's disease (AD). Accordingly, the identification of peculiar biochemical patterns reflecting AD-related synaptopathy in blood and cerebrospinal fluid (CSF) could have relevant diagnostic and prognostic implications. In this study, we measured by High-Performance Liquid Chromatography the amount of glutamate, glutamine and glycine in post-mortem brain samples of AD patients, as well as in CSF and blood serum of drug-free subjects encompassing the whole AD clinical spectrum (pre-clinical AD, n = 18, mild cognitive impairment-AD, n = 29, dementia AD, n = 30). Interestingly, we found that glutamate and glycine levels, as well as total tau protein content, were significantly reduced in the superior frontal gyrus of patients with AD, compared with non-demented controls. No significant change was also found in glutamate, glutamine and glycine CSF concentrations between AD patients and neurological controls. Remarkably, serum glutamate levels were significantly higher in patients affected by early AD phases compared to controls, and were negatively correlated with CSF total tau levels. Conversely, serum glutamine concentration was significantly increased in AD patients, with a negative correlation with MMSE performances. Finally, we reported a significant correlation between serum L-glutamate concentrations and CDR score in female but not in male cohort of AD subjects. Overall, our results suggest that serum glutamate and glutamine levels in AD patients could vary across disease stages, potentially reflecting the progressive alteration of glutamatergic signaling during neurodegenerative processes.
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9
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Frieg B, Görg B, Qvartskhava N, Jeitner T, Homeyer N, Häussinger D, Gohlke H. Mechanism of Fully Reversible, pH-Sensitive Inhibition of Human Glutamine Synthetase by Tyrosine Nitration. J Chem Theory Comput 2020; 16:4694-4705. [PMID: 32551588 DOI: 10.1021/acs.jctc.0c00249] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glutamine synthetase (GS) catalyzes an ATP-dependent condensation of glutamate and ammonia to form glutamine. This reaction-and therefore GS-are indispensable for the hepatic nitrogen metabolism. Nitration of tyrosine 336 (Y336) inhibits human GS activity. GS nitration and the consequent loss of GS function are associated with a broad range of neurological diseases. The mechanism by which Y336 nitration inhibits GS, however, is not understood. Here, we show by means of unbiased MD simulations, binding, and configurational free energy computations that Y336 nitration hampers ATP binding but only in the deprotonated and negatively charged state of residue 336. By contrast, for the protonated and neutral state, our computations indicate an increased binding affinity for ATP. pKa computations of nitrated Y336 within GS predict a pKa of ∼5.3. Thus, at physiological pH, nitrated Y336 exists almost exclusively in the deprotonated and negatively charged state. In vitro experiments confirm these predictions, in that, the catalytic activity of nitrated GS is decreased at pH 7 and 6 but not at pH 4. These results indicate a novel, fully reversible, pH-sensitive mechanism for the regulation of GS activity by tyrosine nitration.
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Affiliation(s)
- Benedikt Frieg
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), and Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Boris Görg
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Natalia Qvartskhava
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Thomas Jeitner
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York 10595, United States
| | - Nadine Homeyer
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), and Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich GmbH, Jülich, Germany
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10
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Hariharan A, Jing Y, Collie ND, Zhang H, Liu P. Altered neurovascular coupling and brain arginine metabolism in endothelial nitric oxide synthase deficient mice. Nitric Oxide 2019; 87:60-72. [PMID: 30877024 DOI: 10.1016/j.niox.2019.03.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/06/2019] [Accepted: 03/10/2019] [Indexed: 12/23/2022]
Abstract
Nitric oxide (NO) produced by endothelial NO synthase (eNOS) is a key regulator of cerebral blood flow (CBF) dynamics. Mice with eNOS deficiency (eNOS-/-) display age-related increases in amyloid beta in the brain and memory deficits, implicating eNOS dysfunction in the neuropathogenesis and/or development of Alzheimer's disease (AD). The present study systematically investigated behavioural, CBF and brain arginine metabolic profile changes in male and female wildtype (WT) and eNOS-/- mice at 14 months of age. eNOS-/- mice displayed altered behaviour in the Y-maze and open field tests. A real-time microcirculation imager revealed a significant sex difference in the basal CBF and significantly increased perfusion response to whisker stimulations in the Barrel cortex in both male and female eNOS-/- mice relative to their sex-matched WT controls. The treatment of 7-nitroindazole blocked the increased perfusion response to whisker stimulations in eNOS-/- mice. Neurochemically, the most intriguing changes were markedly reduced glutamine levels in both male and female eNOS-/- mice in the frontal cortex, hippocampus, parahippocampal region and cerebellum. These findings demonstrate altered behavioural function, neurovascular coupling and brain arginine metabolism (glutamine in particular) under the condition of eNOS deficiency, which further supports the role of eNOS dysfunction in the AD neuropathogenesis.
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Affiliation(s)
- Ashwini Hariharan
- Department of Anatomy, School of Biomedical Sciences, Brain Health Research Centre, University of Otago, Brain Research New Zealand, New Zealand
| | - Yu Jing
- Department of Anatomy, School of Biomedical Sciences, Brain Health Research Centre, University of Otago, Brain Research New Zealand, New Zealand
| | - Nicola D Collie
- Department of Anatomy, School of Biomedical Sciences, Brain Health Research Centre, University of Otago, Brain Research New Zealand, New Zealand
| | - Hu Zhang
- School of Pharmacy, Brain Health Research Centre, University of Otago, Brain Research New Zealand, New Zealand
| | - Ping Liu
- Department of Anatomy, School of Biomedical Sciences, Brain Health Research Centre, University of Otago, Brain Research New Zealand, New Zealand.
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11
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Canfield CA, Bradshaw PC. Amino acids in the regulation of aging and aging-related diseases. TRANSLATIONAL MEDICINE OF AGING 2019. [DOI: 10.1016/j.tma.2019.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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12
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Perez-Nievas BG, Serrano-Pozo A. Deciphering the Astrocyte Reaction in Alzheimer's Disease. Front Aging Neurosci 2018; 10:114. [PMID: 29922147 PMCID: PMC5996928 DOI: 10.3389/fnagi.2018.00114] [Citation(s) in RCA: 174] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 04/03/2018] [Indexed: 12/24/2022] Open
Abstract
Reactive astrocytes were identified as a component of senile amyloid plaques in the cortex of Alzheimer's disease (AD) patients several decades ago. However, their role in AD pathophysiology has remained elusive ever since, in part owing to the extrapolation of the literature from primary astrocyte cultures and acute brain injury models to a chronic neurodegenerative scenario. Recent accumulating evidence supports the idea that reactive astrocytes in AD acquire neurotoxic properties, likely due to both a gain of toxic function and a loss of their neurotrophic effects. However, the diversity and complexity of this glial cell is only beginning to be unveiled, anticipating that astrocyte reaction might be heterogeneous as well. Herein we review the evidence from mouse models of AD and human neuropathological studies and attempt to decipher the main conundrums that astrocytes pose to our understanding of AD development and progression. We discuss the morphological features that characterize astrocyte reaction in the AD brain, the consequences of astrocyte reaction for both astrocyte biology and AD pathological hallmarks, and the molecular pathways that have been implicated in this reaction.
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Affiliation(s)
| | - Alberto Serrano-Pozo
- Alzheimer's Research Unit, MassGeneral Institute for Neurodegenerative Diseases (MIND), Department of Neurology, Massachusetts General Hospital, Boston, MA, United States
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Tumani H, Huss A, Bachhuber F. The cerebrospinal fluid and barriers - anatomic and physiologic considerations. HANDBOOK OF CLINICAL NEUROLOGY 2018; 146:21-32. [PMID: 29110772 DOI: 10.1016/b978-0-12-804279-3.00002-2] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The cerebrospinal fluid (CSF) space consists of the intracerebral ventricles, subarachnoid spaces of the spine and brain (e.g., cisterns and sulci), and the central spinal cord canal. The CSF protects the central nervous system (CNS) in different ways involving metabolic homeostasis, supply of nutrients, functioning as lymphatic system, and regulation of intracranial pressure. CSF is produced by the choroid plexus, brain interstitium, and meninges, and it circulates in a craniocaudal direction from ventricles to spinal subarachnoid space from where it is removed via craniocaudal lymphatic routes and the venous system. The CSF is renewed 3-5 times daily and its molecular constituents are mainly blood-derived (80%), while the remainder consists of brain-derived and intrathecally produced molecules (20%). The CSF space is separated from the vascular system by the blood-CSF barrier (BCB), whereas the blood-brain barrier (BBB), responsible for maintaining the homeostasis of the brain, is located between brain parenchyma and vascular system. Although both barriers have similar functions, they differ with regard to their morphologic and functional properties. Both barrier systems are permeable not only for small molecules, but also for macromolecules and circulating cells. The transport of molecules across the BBB and BCB is regulated by passive diffusion (e.g., albumin, immunoglobulins) and facilitated or active transport (e.g., glucose). The extracellular space volume, potassium buffering, CSF circulation, and interstitial fluid absorption are mainly regulated by aquaporin-4 channels, which are abundantly located at the blood-brain and brain-CSF interfaces. The composition of CSF shows a high dynamic range, and the levels of distinct proteins vary due to several influencing factors, such as site of production (brain or blood-derived), site of sampling (ventricular or lumbar), CSF flow rate (BCB function), diurnal fluctuations of CSF production rate, and finally, molecular size of blood-derived proteins (IgM vs. albumin) and circadian rhythm (glucose, prostaglandin D synthase). Alterations of lumbar CSF are mainly influenced by processes of the CNS located adjacent to the ventricular and spinal CSF space and less by pathologies in cortical areas remote from the ventricles.
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Affiliation(s)
- Hayrettin Tumani
- Department of Neurology, University Hospital Ulm, Ulm, Germany; Specialty Hospital of Neurology, Dietenbronn, Schwendi, Germany.
| | - André Huss
- Department of Neurology, University Hospital Ulm, Ulm, Germany
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p97/VCP promotes degradation of CRBN substrate glutamine synthetase and neosubstrates. Proc Natl Acad Sci U S A 2017; 114:3565-3571. [PMID: 28320958 DOI: 10.1073/pnas.1700949114] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Glutamine synthetase (GS) plays an essential role in metabolism by catalyzing the synthesis of glutamine from glutamate and ammonia. Our recent study showed that CRBN, a direct protein target for the teratogenic and antitumor activities of immunomodulatory drugs such as thalidomide, lenalidomide, and pomalidomide, recognizes an acetyl degron of GS, resulting in ubiquitylation and degradation of GS in response to glutamine. Here, we report that valosin-containing protein (VCP)/p97 promotes the degradation of ubiquitylated GS, resulting in its accumulation in cells with compromised p97 function. Notably, p97 is also required for the degradation of all four known CRBN neo-substrates [Ikaros family zinc finger proteins 1 (IKZF1) and 3 (IKZF3), casein kinase 1α (CK1α), and the translation termination factor GSPT1] whose ubiquitylation is induced by immunomodulatory drugs. Together, these data point to an unexpectedly intimate relationship between the E3 ubiquitin ligase CRL4CRBN and p97 pathways.
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Tahir W, Zafar S, Llorens F, Arora AS, Thüne K, Schmitz M, Gotzmann N, Kruse N, Mollenhauer B, Torres JM, Andréoletti O, Ferrer I, Zerr I. Molecular Alterations in the Cerebellum of Sporadic Creutzfeldt-Jakob Disease Subtypes with DJ-1 as a Key Regulator of Oxidative Stress. Mol Neurobiol 2016; 55:517-537. [PMID: 27975168 DOI: 10.1007/s12035-016-0294-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/08/2016] [Indexed: 12/15/2022]
Abstract
Cerebellar damage and granular and Purkinje cell loss in sporadic Creutzfeldt-Jakob disease (sCJD) highlight a critical involvement of the cerebellum during symptomatic progression of the disease. In this project, global proteomic alterations in the cerebellum of brain from the two most prevalent subtypes (MM1 and VV2) of sCJD were studied. Two-dimensional gel electrophoresis (2DE) coupled mass spectrometric identification revealed 40 proteins in MM1 and 43 proteins in VV2 subtype to be differentially expressed. Of those, 12 proteins showed common differential expression in their expression between two subtypes. Differentially expressed proteins mainly belonged to (i) cell cycle, gene expression and cell death; (ii) cellular stress response/oxidative stress (OS) and (iii) signal transduction and synaptic functions, related molecular functions. We verified 10 differentially expressed proteins at transcriptional and translational level as well. Interestingly, protein deglycase DJ-1 (an antioxidative protein) showed an increase in its messenger RNA (mRNA) expression in both MM1 and VV2 subtypes but protein expression only in VV2 subtype in cerebellum of sCJD patients. Nuclear translocalization of DJ-1 confirmed its expressional alteration due to OS in sCJD. Downstream experiments showed the activation of nuclear factor erythroid-2 related factor 2 (Nrf2)/antioxidative response element (ARE) pathway. DJ-1 protein concentration was significantly increased during the clinical phase in cerebrospinal fluid of sCJD patients and also at presymptomatic and symptomatic stages in cerebellum of humanized PrP transgenic mice inoculated with sCJD (MM1 and VV2) brain. These results suggest the implication of oxidative stress during the pathophysiology of sCJD.
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Affiliation(s)
- Waqas Tahir
- Department of Neurology, University Medical Center Goettingen (UMG) and German Center for Neurodegenerative Diseases (DZNE) Goettingen, Robert-Koch-Str., 40, 37075, Goettingen, Germany
| | - Saima Zafar
- Department of Neurology, University Medical Center Goettingen (UMG) and German Center for Neurodegenerative Diseases (DZNE) Goettingen, Robert-Koch-Str., 40, 37075, Goettingen, Germany.
| | - Franc Llorens
- Department of Neurology, University Medical Center Goettingen (UMG) and German Center for Neurodegenerative Diseases (DZNE) Goettingen, Robert-Koch-Str., 40, 37075, Goettingen, Germany
| | - Amandeep Singh Arora
- Department of Neurology, University Medical Center Goettingen (UMG) and German Center for Neurodegenerative Diseases (DZNE) Goettingen, Robert-Koch-Str., 40, 37075, Goettingen, Germany
| | - Katrin Thüne
- Department of Neurology, University Medical Center Goettingen (UMG) and German Center for Neurodegenerative Diseases (DZNE) Goettingen, Robert-Koch-Str., 40, 37075, Goettingen, Germany
| | - Matthias Schmitz
- Department of Neurology, University Medical Center Goettingen (UMG) and German Center for Neurodegenerative Diseases (DZNE) Goettingen, Robert-Koch-Str., 40, 37075, Goettingen, Germany
| | - Nadine Gotzmann
- Department of Neurology, University Medical Center Goettingen (UMG) and German Center for Neurodegenerative Diseases (DZNE) Goettingen, Robert-Koch-Str., 40, 37075, Goettingen, Germany
| | - Niels Kruse
- Institute of Neuropathology, University Medical Center Goettingen (UMG), Robert-Koch-Str. 40, 37075, Goettingen, Germany
| | - Brit Mollenhauer
- Institute of Neuropathology, University Medical Center Goettingen (UMG), Robert-Koch-Str. 40, 37075, Goettingen, Germany
| | - Juan Maria Torres
- Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Carretera de Algete a El Casar Km. 8,1 S/N, 28130, Valdeolmos, Madrid, Spain
| | - Olivier Andréoletti
- Institut National de la Recherche Agronomique/Ecole Nationale Vétérinaire, Toulouse, France
| | - Isidre Ferrer
- Institute of Neuropathology, Hospitalet de Llobregat, IDIBELL-University Hospital Bellvitge, University of Barcelona, Barcelona, Spain.,Network Center for Biomedical Research of Neurodegenerative Diseases (CIBERNED), Ministry of Health, Institute Carlos III, Madrid, Spain
| | - Inga Zerr
- Department of Neurology, University Medical Center Goettingen (UMG) and German Center for Neurodegenerative Diseases (DZNE) Goettingen, Robert-Koch-Str., 40, 37075, Goettingen, Germany
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16
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Ashby EL, Kierzkowska M, Hull J, Kehoe PG, Hutson SM, Conway ME. Altered Expression of Human Mitochondrial Branched Chain Aminotransferase in Dementia with Lewy Bodies and Vascular Dementia. Neurochem Res 2016; 42:306-319. [PMID: 26980008 PMCID: PMC5283609 DOI: 10.1007/s11064-016-1855-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 01/27/2016] [Accepted: 01/28/2016] [Indexed: 11/22/2022]
Abstract
Cytosolic and mitochondrial human branched chain aminotransferase (hBCATc and hBCATm, respectively) play an integral role in brain glutamate metabolism. Regional increased levels of hBCATc in the CA1 and CA4 region of Alzheimer’s disease (AD) brain together with increased levels of hBCATm in frontal and temporal cortex of AD brains, suggest a role for these proteins in glutamate excitotoxicity. Glutamate toxicity is a key pathogenic feature of several neurological disorders including epilepsy associated dementia, AD, vascular dementia (VaD) and dementia with Lewy bodies (DLB). To further understand if these increases are specific to AD, the expression profiles of hBCATc and hBCATm were examined in other forms of dementia including DLB and VaD. Similar to AD, levels of hBCATm were significantly increased in the frontal and temporal cortex of VaD cases and in frontal cortex of DLB cases compared to controls, however there were no observed differences in hBCATc between groups in these areas. Moreover, multiple forms of hBCATm were observed that were particular to the disease state relative to matched controls. Real-time PCR revealed similar expression of hBCATm mRNA in frontal and temporal cortex for all cohort comparisons, whereas hBCATc mRNA expression was significantly increased in VaD cases compared to controls. Collectively our results suggest that hBCATm protein expression is significantly increased in the brains of DLB and VaD cases, similar to those reported in AD brain. These findings indicate a more global response to altered glutamate metabolism and suggest common metabolic responses that might reflect shared neurodegenerative mechanisms across several forms of dementia.
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Affiliation(s)
- Emma L Ashby
- Department of Applied Science, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK
| | - Marta Kierzkowska
- Department of Applied Science, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK
| | - Jonathon Hull
- Department of Applied Science, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK
| | - Patrick G Kehoe
- Dementia Research Group, Faculty of Medicine and Dentistry, University of Bristol, Bristol, BS16 1LE, UK
| | - Susan M Hutson
- Human Nutrition, Foods, and Exercise, Virginia Tech, 1981 Kraft Drive, 1008 ILSB, Blacksburg, VA, 24060, USA
| | - Myra E Conway
- Department of Applied Science, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK.
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Abnormality in glutamine-glutamate cycle in the cerebrospinal fluid of cognitively intact elderly individuals with major depressive disorder: a 3-year follow-up study. Transl Psychiatry 2016; 6:e744. [PMID: 26926880 PMCID: PMC4872461 DOI: 10.1038/tp.2016.8] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 01/07/2016] [Accepted: 01/14/2016] [Indexed: 12/17/2022] Open
Abstract
Major depressive disorder (MDD), common in the elderly, is a risk factor for dementia. Abnormalities in glutamatergic neurotransmission via the N-methyl-D-aspartate receptor (NMDA-R) have a key role in the pathophysiology of depression. This study examined whether depression was associated with cerebrospinal fluid (CSF) levels of NMDA-R neurotransmission-associated amino acids in cognitively intact elderly individuals with MDD and age- and gender-matched healthy controls. CSF was obtained from 47 volunteers (MDD group, N=28; age- and gender-matched comparison group, N=19) at baseline and 3-year follow-up (MDD group, N=19; comparison group, N=17). CSF levels of glutamine, glutamate, glycine, L-serine and D-serine were measured by high-performance liquid chromatography. CSF levels of amino acids did not differ across MDD and comparison groups. However, the ratio of glutamine to glutamate was significantly higher at baseline in subjects with MDD than in controls. The ratio decreased in individuals with MDD over the 3-year follow-up, and this decrease correlated with a decrease in the severity of depression. No correlations between absolute amino-acid levels and clinical variables were observed, nor were correlations between amino acids and other biomarkers (for example, amyloid-β42, amyloid-β40, and total and phosphorylated tau protein) detected. These results suggest that abnormalities in the glutamine-glutamate cycle in the communication between glia and neurons may have a role in the pathophysiology of depression in the elderly. Furthermore, the glutamine/glutamate ratio in CSF may be a state biomarker for depression.
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18
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Frieg B, Görg B, Homeyer N, Keitel V, Häussinger D, Gohlke H. Molecular Mechanisms of Glutamine Synthetase Mutations that Lead to Clinically Relevant Pathologies. PLoS Comput Biol 2016; 12:e1004693. [PMID: 26836257 PMCID: PMC4737493 DOI: 10.1371/journal.pcbi.1004693] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 12/03/2015] [Indexed: 12/15/2022] Open
Abstract
Glutamine synthetase (GS) catalyzes ATP-dependent ligation of ammonia and glutamate to glutamine. Two mutations of human GS (R324C and R341C) were connected to congenital glutamine deficiency with severe brain malformations resulting in neonatal death. Another GS mutation (R324S) was identified in a neurologically compromised patient. However, the molecular mechanisms underlying the impairment of GS activity by these mutations have remained elusive. Molecular dynamics simulations, free energy calculations, and rigidity analyses suggest that all three mutations influence the first step of GS catalytic cycle. The R324S and R324C mutations deteriorate GS catalytic activity due to loss of direct interactions with ATP. As to R324S, indirect, water-mediated interactions reduce this effect, which may explain the suggested higher GS residual activity. The R341C mutation weakens ATP binding by destabilizing the interacting residue R340 in the apo state of GS. Additionally, the mutation is predicted to result in a significant destabilization of helix H8, which should negatively affect glutamate binding. This prediction was tested in HEK293 cells overexpressing GS by dot-blot analysis: Structural stability of H8 was impaired through mutation of amino acids interacting with R341, as indicated by a loss of masking of an epitope in the glutamate binding pocket for a monoclonal anti-GS antibody by L-methionine-S-sulfoximine; in contrast, cells transfected with wild type GS showed the masking. Our analyses reveal complex molecular effects underlying impaired GS catalytic activity in three clinically relevant mutants. Our findings could stimulate the development of ATP binding-enhancing molecules by which the R324S mutant can be repaired extrinsically. Glutamine synthetase (GS) catalyzes the ATP-dependent ligation of ammonia and glutamate to glutamine, which makes the enzyme essential for human nitrogen metabolism. Three mutations in human GS, R324C, R324S, and R341C, had been identified previously that lead to a glutamine deficiency, resulting in neonatal death in the case of R324C and R341C. However, the molecular mechanisms underlying this impairment of GS activity have remained elusive. Our results from computational biophysics approaches suggest that all three mutants influence the first step of GS’ catalytic cycle, namely ATP or glutamate binding. The analyses reveal a complex set of effects including the loss of direct interactions to substrates, the involvement of water-mediated interactions that alleviate part of the mutation effect, and long-range effects between the catalytic site and structural parts distant from it. As to the latter, experimental validation is in line with our prediction of a significant destabilization of helix H8 in the R341C mutant, which should negatively affect glutamate binding. Finally, our findings could stimulate the development of ATP-binding enhancing molecules for the R324S mutant, which has been suggested to have residual activity, that way extrinsically “repairing” the mutant.
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Affiliation(s)
- Benedikt Frieg
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-University, Düsseldorf, Germany
| | - Boris Görg
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich-Heine-University, Düsseldorf, Germany
| | - Nadine Homeyer
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-University, Düsseldorf, Germany
| | - Verena Keitel
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich-Heine-University, Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich-Heine-University, Düsseldorf, Germany
- * E-mail: (DH); (HG)
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-University, Düsseldorf, Germany
- * E-mail: (DH); (HG)
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Jayakumar AR, Norenberg MD. Glutamine Synthetase: Role in Neurological Disorders. ADVANCES IN NEUROBIOLOGY 2016; 13:327-350. [PMID: 27885636 DOI: 10.1007/978-3-319-45096-4_13] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Glutamine synthetase (GS) is an ATP-dependent enzyme found in most species that synthesizes glutamine from glutamate and ammonia. In brain, GS is exclusively located in astrocytes where it serves to maintain the glutamate-glutamine cycle, as well as nitrogen metabolism. Changes in the activity of GS, as well as its gene expression, along with excitotoxicity, have been identified in a number of neurological conditions. The literature describing alterations in the activation and gene expression of GS, as well as its involvement in different neurological disorders, however, is incomplete. This review summarizes changes in GS gene expression/activity and its potential contribution to the pathogenesis of several neurological disorders, including hepatic encephalopathy, ischemia, epilepsy, Alzheimer's disease, amyotrophic lateral sclerosis, traumatic brain injury, Parkinson's disease, and astroglial neoplasms. This review also explores the possibility of targeting GS in the therapy of these conditions.
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Affiliation(s)
| | - Michael D Norenberg
- Laboratory of Neuropathology, Veterans Affairs Medical Center, Miami, FL, USA.
- Departments of Pathology, University of Miami School of Medicine, 016960, Miami, FL, 33101, USA.
- Departments of Biochemistry & Molecular Biology, University of Miami School of Medicine, Miami, FL, USA.
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20
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Eid T, Gruenbaum SE, Dhaher R, Lee TSW, Zhou Y, Danbolt NC. The Glutamate-Glutamine Cycle in Epilepsy. ADVANCES IN NEUROBIOLOGY 2016; 13:351-400. [PMID: 27885637 DOI: 10.1007/978-3-319-45096-4_14] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Epilepsy is a complex, multifactorial disease characterized by spontaneous recurrent seizures and an increased incidence of comorbid conditions such as anxiety, depression, cognitive dysfunction, and sudden unexpected death. About 70 million people worldwide are estimated to suffer from epilepsy, and up to one-third of all people with epilepsy are expected to be refractory to current medications. Development of more effective and specific antiepileptic interventions is therefore requisite. Perturbations in the brain's glutamate-glutamine cycle, such as increased extracellular levels of glutamate, loss of astroglial glutamine synthetase, and changes in glutaminase and glutamate dehydrogenase, are frequently encountered in patients with epilepsy. Hence, manipulations of discrete glutamate-glutamine cycle components may represent novel approaches to treat the disease. The goal of his review is to discuss some of the glutamate-glutamine cycle components that are altered in epilepsy, particularly neurotransmitters and metabolites, enzymes, amino acid transporters, and glutamate receptors. We will also review approaches that potentially could be used in humans to target the glutamate-glutamine cycle. Examples of such approaches are treatment with glutamate receptor blockers, glutamate scavenging, dietary intervention, and hypothermia.
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Affiliation(s)
- Tore Eid
- Department of Laboratory Medicine, Yale School of Medicine, 330 Cedar Street, 208035, New Haven, CT, 06520-8035, USA.
| | - Shaun E Gruenbaum
- Department of Anesthesiology, Yale School of Medicine, New Haven, CT, USA
| | - Roni Dhaher
- Department of Laboratory Medicine, Yale School of Medicine, 330 Cedar Street, 208035, New Haven, CT, 06520-8035, USA
| | - Tih-Shih W Lee
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
| | - Yun Zhou
- Department of Molecular Medicine, Institute for Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Niels Christian Danbolt
- Department of Molecular Medicine, Institute for Basic Medical Sciences, University of Oslo, Oslo, Norway
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Fluteau A, Ince PG, Minett T, Matthews FE, Brayne C, Garwood CJ, Ratcliffe LE, Morgan S, Heath PR, Shaw PJ, Wharton SB, Simpson JE. The nuclear retention of transcription factor FOXO3a correlates with a DNA damage response and increased glutamine synthetase expression by astrocytes suggesting a neuroprotective role in the ageing brain. Neurosci Lett 2015; 609:11-7. [PMID: 26455863 PMCID: PMC4674771 DOI: 10.1016/j.neulet.2015.10.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 10/01/2015] [Accepted: 10/01/2015] [Indexed: 01/14/2023]
Abstract
The accumulation of reactive oxygen species leading to oxidative damage and cell death plays an important role in a number of neurodegenerative disorders. FOXO3a, the main isoform of FOXO transcription factors, mediates the cellular response to oxidative stress by regulating the expression of genes involved in DNA repair and glutamine metabolism, including glutamine synthetase (GS). Immunohistochemical investigation of the population-based neuropathology cohort of the Medical Research Council's Cognitive Function and Ageing Study (MRC CFAS) demonstrates that nuclear retention of FOXO3a significantly correlates with a DNA damage response and with GS expression by astrocytes. Furthermore, we show that GS expression correlates with increasing Alzheimer-type pathology in this ageing cohort. Our findings suggest that in response to oxidative stress, the nuclear retention of FOXO3a in astrocytes upregulates expression of GS as a neuroprotective mechanism. However, the activity of GS may be compromised by increasing levels of oxidative stress in the ageing brain resulting in dysfunctional enzyme activity, neuronal excitotoxic damage and cognitive impairment.
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Affiliation(s)
- Adeline Fluteau
- Sheffield Institute for Translational Neuroscience, University of Sheffield, United Kingdom; MRC Human Genetics Unit, University of Edinburgh, United Kingdom
| | - Paul G Ince
- Sheffield Institute for Translational Neuroscience, University of Sheffield, United Kingdom
| | - Thais Minett
- Institute of Public Health, University of Cambridge, United Kingdom; Department of Radiology, University of Cambridge, United Kingdom
| | - Fiona E Matthews
- MRC Biostatistics Unit, Cambridge, United Kingdom; Institute of Health and Society, University of Newcastle, United Kingdom; Faculty of Life Sciences, University of Manchester, United Kingdom
| | - Carol Brayne
- Institute of Public Health, University of Cambridge, United Kingdom
| | - Claire J Garwood
- Sheffield Institute for Translational Neuroscience, University of Sheffield, United Kingdom
| | - Laura E Ratcliffe
- Sheffield Institute for Translational Neuroscience, University of Sheffield, United Kingdom
| | - Sarah Morgan
- Sheffield Institute for Translational Neuroscience, University of Sheffield, United Kingdom
| | - Paul R Heath
- Sheffield Institute for Translational Neuroscience, University of Sheffield, United Kingdom
| | - Pamela J Shaw
- Sheffield Institute for Translational Neuroscience, University of Sheffield, United Kingdom
| | - Stephen B Wharton
- Sheffield Institute for Translational Neuroscience, University of Sheffield, United Kingdom.
| | - Julie E Simpson
- Sheffield Institute for Translational Neuroscience, University of Sheffield, United Kingdom
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Doert A, Pilatus U, Zanella F, Müller WE, Eckert GP. ¹H- and ¹³C-NMR spectroscopy of Thy-1-APPSL mice brain extracts indicates metabolic changes in Alzheimer's disease. J Neural Transm (Vienna) 2015; 122:541-50. [PMID: 25742870 DOI: 10.1007/s00702-015-1387-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 02/22/2015] [Indexed: 01/17/2023]
Abstract
Biochemical alterations underlying the symptoms and pathomechanisms of Alzheimer's disease (AD) are not fully understood. However, alterations of glucose metabolism and mitochondrial dysfunction certainly play an important role. (1)H- and (13)C-NMR spectroscopy exhibits promising results in providing information about those alterations in vivo in patients and animals, especially regarding the mitochondrial tricarboxylic acid (TCA) cycle. Accordingly, transgenic mice expressing mutant human amyloid precursor protein (APP(SL))-serving as a model of neuropathological changes in AD-were examined with in vitro 1D (1)H- and 2D (1)H-(13)C-HSQC-NMR spectroscopy after oral administration of 1-(13)C-glucose and acquisition of brain material after 30 min. Perchloric acid extracts were measured using a 500 MHz spectrometer, providing more detailed information compared to in vivo spectra achievable nowadays. Area under curve (AUC) data of metabolite peaks were obtained and normalized in relation to the creatine signal, serving as internal reference. Besides confirming well-known metabolic alterations in AD like decreased N-acetylaspartate (NAA)/Creatine (Cr) ratio, new findings such as a decrease in phosphorylcholine (PC) are presented. Glutamate (Glu) and glutamine (Gln) concentrations were decreased while γ-aminobutyric acid (GABA) was elevated in Thy1-APP(SL) mice. (13)C-NMR spectroscopy revealed a shift in the Glx-2/Glx-4-ratio-where Glx represents a combined Glu/Gln-signal-towards Glx-2 in AD. These findings correlated well with the NAA/Cr-ratio. The Gln-4/Glu-4-ratio is altered in favor of Glu. Our findings suggest that glutamine synthetase (GS), which is predominantly present in glial cells may be impaired in the brain of Thy1-APP(SL) transgenic mice. Since GS is an ATP-dependent enzyme, mitochondrial dysfunction might contribute to reduced activity, which might also account for the increased metabolism of glutamate via the GABA shunt, a metabolic pathway to bypass intra-mitochondrial α-ketoglutarate-dehydrogenase, resulting in elevated GABA levels.
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Affiliation(s)
- A Doert
- Institute of Neuroradiology, Goethe-University Hospital, Frankfurt, Germany
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23
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Timmer NM, Herbert MK, Claassen JAHR, Kuiperij HB, Verbeek MM. Total glutamine synthetase levels in cerebrospinal fluid of Alzheimer's disease patients are unchanged. Neurobiol Aging 2014; 36:1271-3. [PMID: 25577411 DOI: 10.1016/j.neurobiolaging.2014.12.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 11/26/2014] [Accepted: 12/06/2014] [Indexed: 10/24/2022]
Abstract
Decreased cerebral protein and activity levels of glutamine synthetase (GS) have been reported for Alzheimer's disease (AD) patients. Using a recently established method, we quantified total GS levels in cerebrospinal fluid (CSF) from AD patients and control subjects. Furthermore, we investigated if total GS levels in CSF could differentiate AD from frontotemperal dementia and dementia with Lewy bodies patients. As we found no significantly altered total GS levels in any of the patient groups compared with control subjects, we conclude that levels of total GS in CSF have no diagnostic value for AD, dementia with Lewy bodies, or frontotemperal dementia.
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Affiliation(s)
- Nienke M Timmer
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Megan K Herbert
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Jurgen A H R Claassen
- Department of Geriatric Medicine, Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, the Netherlands
| | - H Bea Kuiperij
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Marcel M Verbeek
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud Alzheimer Centre, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, the Netherlands.
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Liu P, Fleete MS, Jing Y, Collie ND, Curtis MA, Waldvogel HJ, Faull RLM, Abraham WC, Zhang H. Altered arginine metabolism in Alzheimer's disease brains. Neurobiol Aging 2014; 35:1992-2003. [PMID: 24746363 DOI: 10.1016/j.neurobiolaging.2014.03.013] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 02/27/2014] [Accepted: 03/14/2014] [Indexed: 12/21/2022]
Abstract
L-arginine is a semi-essential amino acid with a number of bioactive metabolites. Accumulating evidence suggests the implication of altered arginine metabolism in the pathogenesis of Alzheimer's disease (AD). The present study systematically compared the metabolic profile of L-arginine in the superior frontal gyrus, hippocampus, and cerebellum from AD (mean age 80 years) and normal (mean age 80 or 60 years) cases. The activity and protein expression of nitric oxide synthase and arginase were altered with AD and age in a region-specific manner. There were also AD- and age-related changes in the tissue concentrations of L-arginine and its downstream metabolites (L-citrulline, L-ornithine, agmatine, putrescine, spermidine, spermine, glutamate, γ-aminobutyric acid, and glutamine) in a metabolite- or region-specific manner. These findings demonstrate that arginine metabolism is dramatically altered in diverse regions of AD brains, thus meriting further investigation to understand its role in the pathogenesis and/or progression of the disease.
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Affiliation(s)
- Ping Liu
- Department of Anatomy, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand.
| | - Michael S Fleete
- Department of Anatomy, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Yu Jing
- Department of Anatomy, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Nicola D Collie
- Department of Anatomy, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Maurice A Curtis
- Centre for Brain Research and Department of Anatomy with Radiology, University of Auckland, New Zealand
| | - Henry J Waldvogel
- Centre for Brain Research and Department of Anatomy with Radiology, University of Auckland, New Zealand
| | - Richard L M Faull
- Centre for Brain Research and Department of Anatomy with Radiology, University of Auckland, New Zealand
| | - Wickliffe C Abraham
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand; Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Hu Zhang
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand; School of Pharmacy, University of Otago, Dunedin, New Zealand
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Astrocytes and glutamate homoeostasis in Alzheimer's disease: a decrease in glutamine synthetase, but not in glutamate transporter-1, in the prefrontal cortex. ASN Neuro 2013; 5:273-82. [PMID: 24059854 PMCID: PMC3791522 DOI: 10.1042/an20130017] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Astrocytes control tissue equilibrium and hence define the homoeostasis and function of the CNS (central nervous system). Being principal homoeostatic cells, astroglia are fundamental for various forms of neuropathology, including AD (Alzheimer's disease). AD is a progressive neurodegenerative disorder characterized by the loss of cognitive functions due to specific lesions in mnesic-associated regions, including the mPFC (medial prefrontal cortex). Here, we analyzed the expression of GS (glutamine synthetase) and GLT-1 (glutamate transporter-1) in astrocytes in the mPFC during the progression of AD in a triple-transgenic mouse model (3xTg-AD). GS is an astrocyte-specific enzyme, responsible for the intracellular conversion of glutamate into glutamine, whereas the removal of glutamate from the extracellular space is accomplished mainly by astroglia-specific GLT-1. We found a significant decrease in the numerical density (Nv, cells/mm3) of GS-positive astrocytes from early to middle ages (1–9 months; at the age of 1 month by 17%, 6 months by 27% and 9 months by 27% when compared with control animals) in parallel with a reduced expression of GS (determined by Western blots), which started at the age of 6 months and was sustained up to 12 months of age. We did not, however, find any changes in the expression of GLT-1, which implies an intact glutamate uptake mechanism. Our results indicate that the decrease in GS expression may underlie a gradual decline in the vital astrocyte-dependent glutamate–glutamine conversion pathway, which in turn may compromise glutamate homoeostasis, leading towards failures in synaptic connectivity with deficient cognition and memory.
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Optimisation of the quantification of glutamine synthetase and myelin basic protein in cerebrospinal fluid by a combined acidification and neutralisation protocol. J Immunol Methods 2012; 381:1-8. [DOI: 10.1016/j.jim.2012.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 04/05/2012] [Accepted: 04/05/2012] [Indexed: 11/20/2022]
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Tarasiuk J, Kułakowska A, Drozdowski W, Kornhuber J, Lewczuk P. CSF markers in amyotrophic lateral sclerosis. J Neural Transm (Vienna) 2012; 119:747-57. [DOI: 10.1007/s00702-012-0806-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 04/16/2012] [Indexed: 11/29/2022]
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Glutamine acts as a neuroprotectant against DNA damage, beta-amyloid and H2O2-induced stress. PLoS One 2012; 7:e33177. [PMID: 22413000 PMCID: PMC3297635 DOI: 10.1371/journal.pone.0033177] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 02/05/2012] [Indexed: 12/04/2022] Open
Abstract
Glutamine is the most abundant free amino acid in the human blood stream and is ‘conditionally essential’ to cells. Its intracellular levels are regulated both by the uptake of extracellular glutamine via specific transport systems and by its intracellular synthesis by glutamine synthetase (GS). Adding to the regulatory complexity, when extracellular glutamine is reduced GS protein levels rise. Unfortunately, this excess GS can be maladaptive. GS overexpression is neurotoxic especially if the cells are in a low-glutamine medium. Similarly, in low glutamine, the levels of multiple stress response proteins are reduced rendering cells hypersensitive to H2O2, zinc salts and DNA damage. These altered responses may have particular relevance to neurodegenerative diseases of aging. GS activity and glutamine levels are lower in the Alzheimer's disease (AD) brain, and a fraction of AD hippocampal neurons have dramatically increased GS levels compared with control subjects. We validated the importance of these observations by showing that raising glutamine levels in the medium protects cultured neuronal cells against the amyloid peptide, Aβ. Further, a 10-day course of dietary glutamine supplementation reduced inflammation-induced neuronal cell cycle activation, tau phosphorylation and ATM-activation in two different mouse models of familial AD while raising the levels of two synaptic proteins, VAMP2 and synaptophysin. Together, our observations suggest that healthy neuronal cells require both intracellular and extracellular glutamine, and that the neuroprotective effects of glutamine supplementation may prove beneficial in the treatment of AD.
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Vermeiren Y, Le Bastard N, Clark CM, Engelborghs S, De Deyn PP. Serum glutamine synthetase has no value as a diagnostic biomarker for Alzheimer's disease. Neurochem Res 2011; 36:1858-62. [PMID: 21597934 DOI: 10.1007/s11064-011-0504-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2011] [Indexed: 11/25/2022]
Abstract
In order to test whether serum glutamine synthetase (GS) is of potential diagnostic value for Alzheimer's disease (AD), we set up a study to compare serum GS concentrations between AD patients and control subjects. The study population (n = 165) consisted of AD patients (n = 94) and age-matched (n = 41) and age-unmatched (n = 30) control subjects. Serum GS analysis was performed by means of ELISA. No significant differences in serum GS levels were found between the AD group and age-matched controls. Age correlated positively with serum GS concentrations in AD patients and control subjects. This study suggests that serum GS levels have no diagnostic value for AD.
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Affiliation(s)
- Yannick Vermeiren
- Laboratory of Neurochemistry and Behavior, Reference Center for Biological Markers of Memory Disorders, Institute Born-Bunge, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Wilrijk, Belgium
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Cummings JL. Biomarkers in Alzheimer's disease drug development. Alzheimers Dement 2011; 7:e13-44. [PMID: 21550318 DOI: 10.1016/j.jalz.2010.06.004] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 06/01/2010] [Accepted: 06/03/2010] [Indexed: 12/27/2022]
Abstract
Developing new therapies for Alzheimer's disease (AD) is critically important to avoid the impending public health disaster imposed by this common disorder. Means must be found to prevent, delay the onset, or slow the progression of AD. These goals will be achieved by identifying disease-modifying therapies and testing them in clinical trials. Biomarkers play an increasingly important role in AD drug development. In preclinical testing, they assist in decisions to develop an agent. Biomarkers in phase I provide insights into toxic responses and drug metabolism and in Phase II proof-of-concept trials they facilitate go/no-go decisions and dose finding. Biomarkers can play a role in identifying presymptomatic patients or specific patient subgroups. They can provide evidence of target engagement before clinical changes can be expected. Brain imaging can serve as a primary outcome in Phase II trials and as a key secondary outcome in Phase III trials. Magnetic resonance imaging is currently best positioned for use in large multicenter clinical trials. Cerebrospinal fluid (CSF) measures of amyloid beta protein (Aβ), tau protein, and hyperphosphorylated tau (p-tau) protein are sensitive and specific to the diagnosis of AD and may serve as inclusion criteria and possibly as outcomes in clinical trials targeting relevant pathways. Plasma measures of Aβ are of limited diagnostic value but may provide important information as a measure of treatment response. A wide variety of measures of detectable products of cellular processes are being developed as possible biomarkers accessible in the cerebrospinal fluid and plasma or serum. Surrogate markers that can function as outcomes in pivotal trials and reliably predict clinical outcomes are needed to facilitate primary prevention trials of asymptomatic persons where clinical measures may be of limited value. Fit-for-purpose biomarkers are increasingly available to guide AD drug development decisions.
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Affiliation(s)
- Jeffrey L Cummings
- Cleveland Clinic Lou Ruvo Center for Brain Health, Cleveland Clinic Neurological Institute, Las Vegas, NV, USA.
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Fernandes SP, Dringen R, Lawen A, Robinson SR. Inactivation of astrocytic glutamine synthetase by hydrogen peroxide requires iron. Neurosci Lett 2010; 490:27-30. [PMID: 21167257 DOI: 10.1016/j.neulet.2010.12.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 12/03/2010] [Accepted: 12/08/2010] [Indexed: 11/16/2022]
Abstract
The specific activity of brain glutamine synthetase (GS) is lowered in several neurodegenerative diseases that involve iron-mediated oxidative stress. The present study has investigated whether H₂O₂ directly inactivates GS or whether GS is primarily inactivated by hydroxyl radicals that are produced by the Fenton reaction when H₂O₂ reacts with ferrous iron. Exposure of purified sheep brain GS to supraphysiological concentrations of H₂O₂ (1 mM for 30 min) reduced its specific activity by only 41%, indicating that the enzyme is fairly resistant to oxidation by peroxide. However, the enzyme was completely inactivated when co-incubated with H₂O₂, iron and ascorbate, indicating a vulnerability to oxidation by conditions that favour the production of hydroxyl radicals. Similarly, specific GS activity in cultured mouse astrocytes was resistant to supraphysiological concentrations of H₂O₂, with approximately 37% of activity remaining 3h after incubation with 1mM H₂O₂. This inactivation was prevented by the iron chelators 2,2'-dipyridyl or 1,10-phenanthroline, but not by their non-chelating analogues. These data suggest that inactivation of astrocytic GS is caused by H₂O₂ indirectly via the Fenton reaction as it required the presence of chelatable intracellular iron.
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Affiliation(s)
- S P Fernandes
- Blood-Brain Interactions Group, School of Psychology and Psychiatry, Monash University, Victoria 3800, Australia
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32
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Reactive astrocytes give neurons less support: implications for Alzheimer's disease. Neurobiol Aging 2010; 33:423.e1-13. [PMID: 21051108 DOI: 10.1016/j.neurobiolaging.2010.09.018] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 09/20/2010] [Accepted: 09/20/2010] [Indexed: 11/20/2022]
Abstract
Astrocytes become activated in Alzheimer's disease (AD), contributing to and reinforcing an inflammatory cascade. It is proposed that by transforming from a basal to a reactive state, astrocytes neglect their neurosupportive functions, thus rendering neurons vulnerable to excitotoxicity and oxidative stress. This review considers 3 important astrocytic functions, that when disrupted, can affect neuronal metabolism. These are the uptake of glucose and release of lactate; the uptake of glutamate and release of glutamine; and the uptake of glutathione precursors and release of glutathione. Conditions under which these functions can be manipulated in vitro, as well as examples of possible loss of astrocytic function in AD, are discussed. It is proposed that the targeting of astrocytes with pharmacological agents that are specifically designed to return astrocytes to a quiescent phenotype could represent a fruitful new angle for the therapeutic treatment of AD and other neurodegenerative disorders.
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Tumani H, Teunissen C, Süssmuth S, Otto M, Ludolph AC, Brettschneider J. Cerebrospinal fluid biomarkers of neurodegeneration in chronic neurological diseases. Expert Rev Mol Diagn 2008; 8:479-94. [PMID: 18598229 DOI: 10.1586/14737159.8.4.479] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Chronic neurological diseases (CND) like amyotrophic lateral sclerosis (ALS), dementia or multiple sclerosis (MS) share a chronic progressive course of disease that frequently leads to the common pathological pathway of neurodegeneration, including neuroaxonal damage, apoptosis and gliosis. There is an ongoing search for biomarkers that could support early diagnosis of CND and help to identify responders to interventions in therapeutic treatment trials. Cerebrospinal fluid (CSF) is a promising source of biomarkers in CND, since the CSF compartment is in close anatomical contact with the brain interstitial fluid, where biochemical changes related to CND are reflected. We review recent advances in CSF biomarkers research in CND and thereby focus on markers associated with neurodegeneration.
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Affiliation(s)
- Hayrettin Tumani
- Department of Neurology, University of Ulm, Oberer Eselsberg 45, 89081 Ulm, Germany.
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Shaw LM, Korecka M, Clark CM, Lee VMY, Trojanowski JQ. Biomarkers of neurodegeneration for diagnosis and monitoring therapeutics. Nat Rev Drug Discov 2007; 6:295-303. [PMID: 17347655 DOI: 10.1038/nrd2176] [Citation(s) in RCA: 259] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Rapid progress towards understanding the molecular underpinnings of neurodegenerative disorders such as Alzheimer's disease is revolutionizing drug discovery for these conditions. Furthermore, the development of models for these disorders is accelerating efforts to translate insights related to neurodegenerative mechanisms into disease-modifying therapies. However, there is an urgent need for biomarkers to diagnose neurodegenerative disorders early in their course, when therapy is likely to be most effective, and to monitor responses of patients to new therapies. As research related to this need is currently most advanced for Alzheimer's disease, this Review focuses on progress in the development and validation of biomarkers to improve the diagnosis and treatment of Alzheimer's disease and related disorders.
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Affiliation(s)
- Leslie M Shaw
- Department of Pathology and Laboratory Medicine, The University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
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35
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Singh U, Panchanadikar V, Sarkar D. Development of a Simple Assay Protocol for High-Throughput Screening of Mycobacterium tuberculosis Glutamine Synthetase for the Identification of Novel Inhibitors. ACTA ACUST UNITED AC 2005; 10:725-9. [PMID: 16129778 DOI: 10.1177/1087057105278013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mycobacterium tuberculosis glutamine synthetase (GS) is an essential enzyme involved in the pathogenicity of the organism. The screening of a compound library using a robust high-throughput screening (HTS) assay is currently thought to be the most efficient way of getting lead molecules, which are potent inhibitors for this enzyme. The authors have purified the enzyme to a >90% level from the recombinant Escherichia coli strain YMC21E, and it was used for partial characterization as well as standardization experiments. The results indicated that the Kmof the enzyme for L-glutamine and hydroxylamine were 60 mM and 8.3 mM, respectively. The Km for ADP, arsenate, and Mn2+ were 2 [.proportional]M, 5 [.proportional]M, and 25 [.proportional]M, respectively. When the components were adjusted according to their Km values, the activity remained constant for at least 3 h at both 25° C and 37° C. The Z′ factor determined in microplate format indicated robustness of the assay. When the signal/noise ratios were determined for different assay volumes, it was observed that the 200-[.proportional]l volume was found to be optimum. The DMSO tolerance of the enzyme was checked up to 10%, with minimal inhibition. The IC50 value determined for L-methionine S-sulfoximine on the enzyme activity was 3 mM. Approximately 18,000 small molecules could be screened per day using this protocol by a Beckman Coulter HTS setup.
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Affiliation(s)
- Upasana Singh
- Combichem Bioresource Center, National Chemical Laboratory, Dr. Homi Bhabha Rd., Pune 411008, India
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36
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White LR, Gårseth M, Aasly J, Sonnewald U. Cerebrospinal fluid from patients with dementia contains increased amounts of an unknown factor. J Neurosci Res 2004; 78:297-301. [PMID: 15378514 DOI: 10.1002/jnr.20241] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Increased levels of an unidentified peak have been found in cerebrospinal fluid (CSF) from patients with Alzheimer's disease or vascular dementia compared to the level in healthy controls using proton magnetic resonance spectroscopy. No increase was found in patients with amyotrophic lateral sclerosis. Reexamination of spectra from a study published previously (Gårseth et al. [2000] J. Neurosci. Res. 60:779-782), however, shows that this peak was also elevated significantly in CSF from patients with Huntington's disease compared to that in controls. The level in patients with Parkinson's disease, where dementia develops in up to 40% of patients, was not elevated significantly compared to that in controls. To the best of our knowledge, this peak has not yet been identified and we therefore find it appropriate to temporarily designate the name "dementia associated factor" (DAF), although there is as yet no certainty that this substance is specific for these conditions. Apart from a significantly increased level of glutamine in CSF from patients with vascular dementia compared to that in controls, no other significant difference was found for any other metabolite measured in the patient groups using proton magnetic resonance spectroscopy.
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Affiliation(s)
- Linda R White
- Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
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37
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Strong M, Rosenfeld J. Amyotrophic lateral sclerosis: a review of current concepts. AMYOTROPHIC LATERAL SCLEROSIS AND OTHER MOTOR NEURON DISORDERS : OFFICIAL PUBLICATION OF THE WORLD FEDERATION OF NEUROLOGY, RESEARCH GROUP ON MOTOR NEURON DISEASES 2003; 4:136-43. [PMID: 13129799 DOI: 10.1080/14660820310011250] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Amyotrophic lateral sclerosis (ALS), once thought to be a rare neurodegenerative disease, affects between 1.2 and 1.8/100,000 individuals. This age-dependent disorder, similar to other major neurological disorders of the aging population (Alzheimer's and Parkinson's disease) is increasing in incidence at a rate which cannot be accounted for by population aging alone. Multiple clinical variants of ALS are now recognized which are associated with a spectrum of clinical outcomes from aggressive to rather indolent. Three variants of ALS are generally accepted, including the western Pacific type (often associated with dementia), familial (the majority of which are autosomal dominant in their inheritance) and classic sporadic ALS. Considerable biological heterogeneity underlies the disease process of ALS. By the time ALS is clinically evident, derangements at the cellular level in ALS are extensive and include alterations in the cytoskeleton, mitochondrial function, microglial activation, and the metabolism of reactive oxygenating species and glutamate. Our understanding of the genetic aspects of the disease continues to expand. These observations have led to the suggestion that multiple distinct etiologies may be responsible. Recent advances have also included the observation that cognitive decline may be present in a population of patients not previously recognised. Significant advances in both symptomatic and adjunctive therapy have resulted in prolonged quality and duration of life.
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Affiliation(s)
- Michael Strong
- The Department of Clinical Neurological Sciences, The University of Western Ontario, London, Canada.
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Frank RA, Galasko D, Hampel H, Hardy J, de Leon MJ, Mehta PD, Rogers J, Siemers E, Trojanowski JQ. Biological markers for therapeutic trials in Alzheimer's disease. Proceedings of the biological markers working group; NIA initiative on neuroimaging in Alzheimer's disease. Neurobiol Aging 2003; 24:521-36. [PMID: 12714109 DOI: 10.1016/s0197-4580(03)00002-2] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Richard A Frank
- Pharmacia Corporation, Mailstop 134, Peapack, NJ 07977, USA.
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Abstract
Once thought to be a single pathological disease state, amyotrophic lateral sclerosis (ALS) is now recognized to be the limited phenotypic expression of a complex, heterogeneous group of biological processes, resulting in an unrelenting loss of motor neurons. On average, individuals affected with the disease live <5 years. In this article, the complex nature of the pathogenesis of ALS, including features of age dependency, environmental associations, and genetics, is reviewed. Once held to be uncommon, it is now clear that ALS is associated with a frontotemporal dementia and that this process may reflect disturbances in the microtubule-associated tau protein metabolism. The motor neuron ultimately succumbs in a state where significant disruptions in neurofilament metabolism, mitochondrial function, and management of oxidative stress exist. The microenvironment of the neuron becomes a complex milieu in which high levels of glutamate provide a source of chronic excitatory neurotoxicity, and the contributions of activated microglial cells lead to further cascades of motor neuron death, perhaps serving to propagate the disease once established. The final process of motor neuron death encompasses many features of apoptosis, but it is clear that this alone cannot account for all features of motor neuron loss and that aspects of a necrosis-apoptosis continuum are at play. Designing pharmacological strategies to mitigate against this process thus becomes an increasingly complex issue, which is reviewed in this article.
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Affiliation(s)
- Michael J Strong
- Department of Clinical Neurological Sciences, Robarts Research Institute, Room 7OF 10, University Campus, London Health Sciences Centre, University of Western Ontario, 339 Windermere Road, London, Ontario, Canada N6A 5A5.
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40
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Strong MJ. Biochemical markers: summary. AMYOTROPHIC LATERAL SCLEROSIS AND OTHER MOTOR NEURON DISORDERS : OFFICIAL PUBLICATION OF THE WORLD FEDERATION OF NEUROLOGY, RESEARCH GROUP ON MOTOR NEURON DISEASES 2003; 3 Suppl 1:S85-90. [PMID: 12396819 DOI: 10.1080/146608202320374408] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder. Behavioural, cognitive and memory dysfunctions are characteristic symptoms of AD. The formation of amyloid plaques is currently considered as the key event of AD. Other histological hallmarks of the disease are the formation of fibrillary tangles, astrocytosis, and loss of certain neuronal systems in cortical areas of the brain. A great number of possible aetiologic and pathogenetic factors of AD have been published in the course of the last two decades. Among the toxic factors, which have been considered to contribute to the symptoms and progression of AD, ammonia deserves special interest for the following reasons: (a) Ammonia is formed in nearly all tissues and organs of the vertebrate organism; it is the most common endogenous neurotoxic compounds. Its effects on glutamatergic and GABAergic neuronal systems, the two prevailing neuronal systems of the cortical structures, are known for many years. (b) The impairment of ammonia detoxification invariably leads to severe pathology. Several symptoms and histologic aberrations of hepatic encephalopathy (HE), of which ammonia has been recognised as a pathogenetic factor, resemble those of AD. (c) The excessive formation of ammonia in the brains of AD patients has been demonstrated, and it has been shown that some AD patients exhibit elevated blood ammonia concentrations. (d) There is evidence for the involvement of aberrant lysosomal processing of beta-amyloid precursor protein (beta-APP) in the formation of amyloid deposits. Ammonia is the most important natural modulator of lysosomal protein processing. (e) Inflammatory processes and activation of microglia are widely believed to be implicated in the pathology of AD. Ammonia is able to affect the characteristic functions of microglia, such as endocytosis, and cytokine production. Based on these facts, an ammonia hypothesis of AD has first been suggested in 1993. In the present review old and new observations are discussed, which are in support of the notion that ammonia is a factor able to produce symptoms of AD and to affect the progression of the disease.
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Affiliation(s)
- Nikolaus Seiler
- Laboratory of Nutritional Oncology, Institut de Recherche Contre les Cancers de l'Appareil Digestif, Strasbourg, France.
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42
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Takahashi M, Stanton E, Moreno JI, Jackowski G. Immunoassay for Serum Glutamine Synthetase in Serum: Development, Reference Values, and Preliminary Study in Dementias. Clin Chem 2002. [DOI: 10.1093/clinchem/48.2.375] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Miyoko Takahashi
- Syn-X Pharma Inc., 6354 Viscount Rd., Mississauga, Ontario, L4V 1H3 Canada
| | - Eric Stanton
- Syn-X Pharma Inc., 6354 Viscount Rd., Mississauga, Ontario, L4V 1H3 Canada
| | - J Ignacio Moreno
- Syn-X Pharma Inc., 6354 Viscount Rd., Mississauga, Ontario, L4V 1H3 Canada
| | - George Jackowski
- Syn-X Pharma Inc., 6354 Viscount Rd., Mississauga, Ontario, L4V 1H3 Canada
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Torreilles F, Touchon J. Pathogenic theories and intrathecal analysis of the sporadic form of Alzheimer's disease. Prog Neurobiol 2002; 66:191-203. [PMID: 11943451 DOI: 10.1016/s0301-0082(01)00030-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Alzheimer's disease (AD) is an age-dependent dementia characterized by progressive loss of cognitive functions and by characteristic pathological changes in the brain: the formation of aggregates extracellularly by beta-amyloid (Abeta) peptide and intracellularly by tau proteins. The disease presents several major diagnostic difficulties: (1) AD develops slowly; (2) analysis of damaged brain tissues is difficult, requiring a biopsy which poses ethical problems; (3) no biochemical markers are available for the diagnosis and monitoring of the disease progression. Since the cerebrospinal fluid (CSF) is in contact with the extracellular space of the brain, many studies have tried to correlate the levels of the intrathecal peptides and amino acids and the development of dementia. The present review analyzes the main results of intrathecal content analyses in light of pathogenic theories proposed to explain the damage associated with AD and observed in the brain of patients by postmortem examination.
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Affiliation(s)
- François Torreilles
- CNRS UMR 5094, Institut de Biotechnologie et Pharmacologie, UFR Pharmacie, 15 Avenue Charles Flahault, 34093 Montpellier Cedex 5, France.
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Karitzky J, Ludolph AC. Imaging and neurochemical markers for diagnosis and disease progression in ALS. J Neurol Sci 2001; 191:35-41. [PMID: 11676990 DOI: 10.1016/s0022-510x(01)00628-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Based on the development of a transgenic animal model, an increasing number of experimental strategies have revealed the potential to modify the selective degeneration of motor neurons, a feature unique to motor neuron diseases such as amyotrophic lateral sclerosis (ALS). The translation of this success into therapeutic effects in human diseases is a challenge of the future. For this purpose, tools must be developed which serve as diagnostic and surrogate markers for diagnosis and disease progression. Currently, to understand the pathogenesis of the spinal cord disease, the focus remains on more traditional electrodiagnostic techniques. For the characterization of the involvement of brain structures, imaging techniques are increasingly explored. This review focuses on the use of imaging techniques as surrogate markers for the involvement of the brain in motor neuron disorders, but also tries to point out that the final goal will be the development of cheap biochemical markers for the screening of populations at risk.
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Affiliation(s)
- J Karitzky
- Department of Neurology, University of Ulm, Steinhövelstrasse 9, 89075, Ulm, Germany
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Kerokoski P, Soininen H, Pirttilä T. Beta-amyloid (1-42) affects MTT reduction in astrocytes: implications for vesicular trafficking and cell functionality. Neurochem Int 2001; 38:127-34. [PMID: 11137881 DOI: 10.1016/s0197-0186(00)00071-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Beta-amyloid (Abeta) peptide deposition in the brains of Alzheimer's disease patients results in reactive astrogliosis which may enhance neuronal cell death. Abeta has also been reported to impair important supportive astrocyte functions, such as glutamate uptake in vitro. We studied the effect of amyloid beta-peptide (Abeta) on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction, cellular ATP content, lactate release, and proliferation using neonatal rat astrocyte cultures. Abeta(1-42) decreased MTT reduction potently in the absence of cell death, but did not affect cellular ATP levels or lactate release. Moreover, the cells displayed increased proliferation after incubation with Abeta(1-42), confirming that the decreased MTT reduction was not deleterious to cell viability. Abeta(1-42) enhanced transfer of MTT dye to the cell surface leading to cessation of MTT reduction and cell death. Bafilomycin A1, but not brefeldin A, prevented the enhanced trafficking of MTT, suggesting that lysosomes, but not Golgi apparatus, are involved. Our results show that the viability of astrocytes themselves is not diminished by beta-amyloid peptide. However, Abeta alters vesicular trafficking in astrocytes, which may disturb the supportive function of astrocytes in the brains of patients with Alzheimer's disease.
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Affiliation(s)
- P Kerokoski
- Department of Neuroscience and Neurology, University of Kupio, Finland.
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Litvan I, Dickson DW, Buttner-Ennever JA, Delacourte A, Hutton M, Dubois B, Golbe LI, Hallett M, Schellenberg GD, Standaert D, Brooks DJ, Price D. Research goals in progressive supranuclear palsy. Mov Disord 2001; 15:446-458. [DOI: 10.1002/1531-8257(200005)15:3<446::aid-mds1005>3.0.co;2-c] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2000] [Revised: 03/27/2000] [Accepted: 04/18/2000] [Indexed: 12/19/2022] Open
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Teismann P, Ferger B. Effects of ensaculin on dopamine metabolite levels and K(+)-induced glutamate release. Eur J Pharmacol 2000; 398:247-50. [PMID: 10854836 DOI: 10.1016/s0014-2999(00)00290-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In vivo microdialysis with the new antidementia compound ensaculin was performed in freely moving rats to study the alterations in dopaminergic and glutamatergic neurotransmission. Ensaculin (0.1 and 1 mg/kg i.p.) significantly increased extracellular levels of the dopamine metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). Furthermore, ensaculin (1 mg/kg i.p.) showed a non-significant tendency to reduce the K(+)-induced glutamate release. The data suggest that ensaculin may have moderate D(2) antagonistic properties. Thus, besides its possible role as a cognitive enhancer, ensaculin may also have moderate antipsychotic properties.
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Affiliation(s)
- P Teismann
- Institute of Pharmacology and Toxicology, Faculty of Pharmacy, University of Marburg, Ketzerbach 63, D-35032, Marburg, Germany
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