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Ke T, Sidoryk-Wegrzynowicz M, Pajarillo E, Rizor A, Soares FAA, Lee E, Aschner M. Role of Astrocytes in Manganese Neurotoxicity Revisited. Neurochem Res 2019; 44:2449-2459. [PMID: 31571097 PMCID: PMC7757856 DOI: 10.1007/s11064-019-02881-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/13/2019] [Accepted: 09/16/2019] [Indexed: 12/17/2022]
Abstract
Manganese (Mn) overexposure is a public health concern due to its widespread industrial usage and the risk for environmental contamination. The clinical symptoms of Mn neurotoxicity, or manganism, share several pathological features of Parkinson's disease (PD). Biologically, Mn is an essential trace element, and Mn in the brain is preferentially localized in astrocytes. This review summarizes the role of astrocytes in Mn-induced neurotoxicity, specifically on the role of neurotransmitter recycling, neuroinflammation, and genetics. Mn overexposure can dysregulate astrocytic cycling of glutamine (Gln) and glutamate (Glu), which is the basis for Mn-induced excitotoxic neuronal injury. In addition, reactive astrocytes are important mediators of Mn-induced neuronal damage by potentiating neuroinflammation. Genetic studies, including those with Caenorhabditis elegans (C. elegans) have uncovered several genes associated with Mn neurotoxicity. Though we have yet to fully understand the role of astrocytes in the pathologic changes characteristic of manganism, significant strides have been made over the last two decades in deciphering the role of astrocytes in Mn-induced neurotoxicity and neurodegeneration.
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Affiliation(s)
- Tao Ke
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Marta Sidoryk-Wegrzynowicz
- Laboratory of Pathoneurochemistry, Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawinskiego Street, 02-106, Warsaw, Poland
| | - Edward Pajarillo
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Asha Rizor
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Félix Alexandre Antunes Soares
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.,Department of Biochemistry and Molecular Biology, Federal University of Santa Maria, Santa Maria, RS, Brazil
| | - Eunsook Lee
- Department of Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA. .,Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer Building, Room 209, Bronx, NY, 10461, USA.
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Suzuki M, Toki H, Furuya A, Ando H. Establishment of monoclonal antibodies against cell surface domains of ASCT2/SLC1A5 and their inhibition of glutamine-dependent tumor cell growth. Biochem Biophys Res Commun 2016; 482:651-657. [PMID: 27865832 DOI: 10.1016/j.bbrc.2016.11.089] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 11/15/2016] [Indexed: 12/20/2022]
Abstract
Human alanine-serine-cysteine transporter 2 (ASCT2; SLC1A5) is a major transporter of the amino acid glutamine that is known to be overexpressed in certain malignant tumors. In this study, we generated specific monoclonal antibodies (MAbs) against ASCT2 by establishing an ASCT2-expressing Chinese hamster ovary cell line that was used to immunize mice and rats. The MAbs KM4008, KM4012, and KM4018 against ASCT2 were isolated through a cell-based screen; these specifically bound to ASCT2-positive cells, as determined by flow cytometry and immunoprecipitation. In addition, the antibodies suppressed glutamine-dependent growth of WiDr colorectal cancer cells. These results provide evidence supporting the use of MAbs against ASCT2 as an effective therapeutic strategy for cancer treatment.
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Affiliation(s)
- Masayo Suzuki
- R&D Division, Tokyo Research Park, Kyowa Hakko Kirin Co., Ltd, Machida-shi, Tokyo, Japan
| | - Hiroe Toki
- R&D Division, Tokyo Research Park, Kyowa Hakko Kirin Co., Ltd, Machida-shi, Tokyo, Japan
| | - Akiko Furuya
- R&D Division, Tokyo Research Park, Kyowa Hakko Kirin Co., Ltd, Machida-shi, Tokyo, Japan
| | - Hiroshi Ando
- R&D Division, Tokyo Research Park, Kyowa Hakko Kirin Co., Ltd, Machida-shi, Tokyo, Japan.
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Sidoryk-Wegrzynowicz M, Aschner M. Manganese toxicity in the central nervous system: the glutamine/glutamate-γ-aminobutyric acid cycle. J Intern Med 2013; 273:466-77. [PMID: 23360507 PMCID: PMC3633698 DOI: 10.1111/joim.12040] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Manganese (Mn) is an essential trace element that is required for maintaining proper function and regulation of numerous biochemical and cellular reactions. Despite its essentiality, at excessive levels Mn is toxic to the central nervous system (CNS). Increased accumulation of Mn in specific brain regions, such as the substantia nigra, globus pallidus and striatum, triggers neurotoxicity resulting in a neurological brain disorder, termed manganism. Mn has been also implicated in the pathophysiology of several other neurodegenerative diseases. Its toxicity is associated with disruption of the glutamine (Gln)/glutamate (Glu)-γ-aminobutyric acid (GABA) cycle (GGC) between astrocytes and neurons, thus leading to changes in Glu-ergic and/or GABAergic transmission and Gln metabolism. Here we discuss the common mechanisms underlying Mn-induced neurotoxicity and their relationship to CNS pathology and GGC impairment.
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Sidoryk-Wegrzynowicz M, Aschner M. Role of astrocytes in manganese mediated neurotoxicity. BMC Pharmacol Toxicol 2013; 14:23. [PMID: 23594835 PMCID: PMC3637816 DOI: 10.1186/2050-6511-14-23] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 04/10/2013] [Indexed: 01/08/2023] Open
Abstract
Astrocytes are responsible for numerous aspects of metabolic support, nutrition, control of the ion and neurotransmitter environment in central nervous system (CNS). Failure by astrocytes to support essential neuronal metabolic requirements plays a fundamental role in the pathogenesis of brain injury and the ensuing neuronal death. Astrocyte-neuron interactions play a central role in brain homeostasis, in particular via neurotransmitter recycling functions. Disruption of the glutamine (Gln)/glutamate (Glu) -γ-aminobutyric acid (GABA) cycle (GGC) between astrocytes and neurons contributes to changes in Glu-ergic and/or GABA-ergic transmission, and is associated with several neuropathological conditions, including manganese (Mn) toxicity. In this review, we discuss recent advances in support of the important roles for astrocytes in normal as well as neuropathological conditions primarily those caused by exposure to Mn.
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Visualization of glutamine transporter activities in living cells using genetically encoded glutamine sensors. PLoS One 2012; 7:e38591. [PMID: 22723868 PMCID: PMC3375291 DOI: 10.1371/journal.pone.0038591] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 05/08/2012] [Indexed: 11/19/2022] Open
Abstract
Glutamine plays a central role in the metabolism of critical biological molecules such as amino acids, proteins, neurotransmitters, and glutathione. Since glutamine metabolism is regulated through multiple enzymes and transporters, the cellular glutamine concentration is expected to be temporally dynamic. Moreover, differentiation in glutamine metabolism between cell types in the same tissue (e.g. neuronal and glial cells) is often crucial for the proper function of the tissue as a whole, yet assessing cell-type specific activities of transporters and enzymes in such heterogenic tissue by physical fractionation is extremely challenging. Therefore, a method of reporting glutamine dynamics at the cellular level is highly desirable. Genetically encoded sensors can be targeted to a specific cell type, hence addressing this knowledge gap. Here we report the development of Föster Resonance Energy Transfer (FRET) glutamine sensors based on improved cyan and yellow fluorescent proteins, monomeric Teal Fluorescent Protein (mTFP)1 and venus. These sensors were found to be specific to glutamine, and stable to pH-changes within a physiological range. Using cos7 cells expressing the human glutamine transporter ASCT2 as a model, we demonstrate that the properties of the glutamine transporter can easily be analyzed with these sensors. The range of glutamine concentration change in a given cell can also be estimated using sensors with different affinities. Moreover, the mTFP1-venus FRET pair can be duplexed with another FRET pair, mAmetrine and tdTomato, opening up the possibility for real-time imaging of another molecule. These novel glutamine sensors will be useful tools to analyze specificities of glutamine metabolism at the single-cell level.
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OCHIAI H, ONDA K, OGIHARA K, NAYA Y, SUGIYAMA H, MARUO T. cDNA Sequence and Tissue Distribution of Canine Na-Dependent Neutral Amino Acid Transporter 2 (ASCT 2). J Vet Med Sci 2012; 74:1505-10. [DOI: 10.1292/jvms.12-0171] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Hideharu OCHIAI
- Research Institute of Biosciences, Azabu University, 1–17–71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252–5201, Japan
| | - Ken ONDA
- Laboratory of Internal Medicine 3, Azabu University, 1–17–71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252–5201, Japan
| | - Kikumi OGIHARA
- Laboratory of Pathology, Azabu University, 1–17–71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252–5201, Japan
| | - Yuko NAYA
- Laboratory of Pathology, Azabu University, 1–17–71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252–5201, Japan
| | - Hiroki SUGIYAMA
- Veterinary Teaching Hospital, Azabu University, 1–17–71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252–5201, Japan
| | - Takuya MARUO
- Veterinary Teaching Hospital, Azabu University, 1–17–71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252–5201, Japan
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Sidoryk-Wegrzynowicz M, Lee E, Mingwei N, Aschner M. Disruption of astrocytic glutamine turnover by manganese is mediated by the protein kinase C pathway. Glia 2011; 59:1732-43. [PMID: 21812036 DOI: 10.1002/glia.21219] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 06/21/2011] [Indexed: 11/11/2022]
Abstract
Manganese (Mn) is a trace element essential for normal human development and is required for the proper functioning of a variety of physiological processes. Chronic exposure to Mn can cause manganism, a neurodegenerative disorder resembling idiopathic Parkinson's disease (PD). Mn(II) neurotoxicity is characterized by astrocytic impairment both in the expression and activity of glutamine (Gln) transporters. Because protein kinase C (PKC) activation leads to the downregulation of a number of neurotransmitter transporters and Mn(II) increases PKC activity, we hypothesized that the PKC signaling pathway contributes to the Mn(II)-mediated disruption of Gln turnover. Our results have shown that Mn exposure increases the phosphorylation of both the PKCα and PKCδ isoforms. PKC activity was also shown to be increased in response to Mn(II) treatment. Corroborating our earlier observations, Mn(II) also caused a decrease in Gln uptake. This effect was blocked by PKC inhibitors. Notably, PKC activation caused a decrease in Gln uptake mediated by systems ASC and N, but had no effect on the activities of systems A and L. Exposure to α-phorbol 12-myristate 13-acetate significantly decreased SNAT3 (system N) and ASCT2 (system ASC) protein levels. Additionally, a co-immunoprecipitation study demonstrated the association of SNAT3 and ASCT2 with the PKCδ isoform, and Western blotting revealed the Mn(II)-mediated activation of PKCδ by proteolytic cleavage. PKC activation was also found to increase SNAT3 and ubiquitin ligase Nedd4-2 binding and to induce hyperubiquitination. Taken together, these findings demonstrate that the Mn(II)-induced dysregulation of Gln homeostasis in astrocytes involves PKCδ signaling accompanied by an increase in ubiquitin-mediated proteolysis.
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Abstract
Relative to other neutral amino acid transporters, the expression levels of ASCT2 and LAT1, are coordinately elevated in a wide spectrum of primary human cancers, suggesting that they are frequently co-opted to support the "tumor metabolome". Each has recently been shown to play important roles in the growth and survival of cancer cell lines, making them potential targets for cancer therapy. The properties and putative relationship of these two amino acid exchangers are discussed in the context of their demonstrated utility in cancer biology, including cellular growth and survival signaling and integrated links to the mammalian target-of-rapamycin (mTOR) kinase.
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Affiliation(s)
- Bryan C Fuchs
- Department of Biology, Saint Louis University, MW128, 3507 Laclede Avenue, St. Louis, MO 63103-2010, USA
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Abstract
Much has been learned about plasma membrane glutamine transporter activities in health and disease over the past 30 years, including their potential regulatory role in metabolism. Since the 1960s, discrimination among individual glutamine transporters was based on functional characteristics such as substrate specificity, ion dependence, and kinetic and regulatory properties. Within the past two years, several genes encoding for proteins with these defined activities (termed "systems") have been isolated from human and rodent cDNA libraries and found to be distributed among four distinct gene families. The Na(+)-dependent glutamine transporter genes isolated thus far are System N (SN1), System A (ATA1, ATA2), System ASC/B(0) (ASCT2 or ATB(0)), System B(0,+) (ATB(0,+)) and System y(+)L (y(+)LAT1, y(+)LAT2). Na(+)-independent glutamine transporter genes encoding for System L (LAT1, LAT2) and System b(0,+) (b(0,+)AT) have also been recently isolated, and similar to y(+)L, have been shown to function as disulfide-linked heterodimers with the 4F2 heavy chain (CD98) or rBAT (related to b(0,+) amino acid transporter). In this review, the molecular features, catalytic mechanisms and tissue distributions of each are addressed. Although most of these transporters mediate the transmembrane movement of several other amino acids, their potential roles in regulating interorgan glutamine flux are discussed. Most importantly, these newly isolated transporter genes provide the long awaited tools necessary to study their molecular regulation during the catabolic states in which glutamine is considered to be "conditionally essential."
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Affiliation(s)
- B P Bode
- Department of Biology, Saint Louis University, St. Louis, MO 63103-2010, USA
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Bussolati O, Dall'Asta V, Franchi-Gazzola R, Sala R, Rotoli BM, Visigalli R, Casado J, Lopez-Fontanals M, Pastor-Anglada M, Gazzola GC. The role of system A for neutral amino acid transport in the regulation of cell volume. Mol Membr Biol 2001; 18:27-38. [PMID: 11396608 DOI: 10.1080/09687680110033756] [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: 10/16/2022]
Abstract
System A is a secondary active, sodium dependent transport system for neutral amino acids. Strictly coupled with Na,K-ATPase, its activity determines the size of the intracellular amino acid pool, through a complex network of metabolic reaction and exchange fluxes. Many hormones and drugs affect system A activity in specific cell models or tissues. In all the cell models tested thus far the activity of the system is stimulated by amino acid starvation, cell cycle progression, and the incubation under hypertonic conditions. These three conditions produce marked alterations of cell volume. The stimulation of system A activity plays an important role in cell volume restoration, through an expansion of the intracellular amino acid pool. Under normal conditions, system A substrates represent a major fraction of cell compatible osmolytes, organic compounds that exert a protein stabilizing effect. It is, therefore, likely that the activation of system A represents a portion of a more complex response triggered by exposure to stresses of various nature. Since system A transporters have been recently cloned, the molecular bases of these regulatory mechanisms will probably be elucidated in a short time.
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Affiliation(s)
- O Bussolati
- Department of Experimental Medicine, University of Parma, Italy.
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