1
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Xia R, Peng HF, Zhang X, Zhang HS. Comprehensive review of amino acid transporters as therapeutic targets. Int J Biol Macromol 2024; 260:129646. [PMID: 38272411 DOI: 10.1016/j.ijbiomac.2024.129646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 01/27/2024]
Abstract
The solute carrier (SLC) family, with more than 400 membrane-bound proteins, facilitates the transport of a wide array of substrates such as nutrients, ions, metabolites, and drugs across biological membranes. Amino acid transporters (AATs) are membrane transport proteins that mediate transfer of amino acids into and out of cells or cellular organelles. AATs participate in many important physiological functions including nutrient supply, metabolic transformation, energy homeostasis, redox regulation, and neurological regulation. Several AATs have been found to significantly impact the progression of human malignancies, and dysregulation of AATs results in metabolic reprogramming affecting tumor growth and progression. However, current clinical therapies that directly target AATs have not been developed. The purpose of this review is to highlight the structural and functional diversity of AATs, the molecular mechanisms in human diseases such as tumors, kidney diseases, and emerging therapeutic strategies for targeting AATs.
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Affiliation(s)
- Ran Xia
- College of Chemistry and Life Science, Beijing University of Technology, Pingleyuan 100(#), District of Chaoyang, Beijing 100124, China
| | - Hai-Feng Peng
- College of Chemistry and Life Science, Beijing University of Technology, Pingleyuan 100(#), District of Chaoyang, Beijing 100124, China
| | - Xing Zhang
- College of Chemistry and Life Science, Beijing University of Technology, Pingleyuan 100(#), District of Chaoyang, Beijing 100124, China
| | - Hong-Sheng Zhang
- College of Chemistry and Life Science, Beijing University of Technology, Pingleyuan 100(#), District of Chaoyang, Beijing 100124, China.
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2
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Shen Z, Xiang M, Chen C, Ding F, Wang Y, Shang C, Xin L, Zhang Y, Cui X. Glutamate excitotoxicity: Potential therapeutic target for ischemic stroke. Biomed Pharmacother 2022; 151:113125. [PMID: 35609367 DOI: 10.1016/j.biopha.2022.113125] [Citation(s) in RCA: 50] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 05/01/2022] [Accepted: 05/13/2022] [Indexed: 11/29/2022] Open
Abstract
Glutamate-mediated excitotoxicity is an important mechanism leading to post ischemic stroke damage. After acute stroke, the sudden reduction in cerebral blood flow is most initially followed by ion transport protein dysfunction and disruption of ion homeostasis, which in turn leads to impaired glutamate release, reuptake, and excessive N-methyl-D-aspartate receptor (NMDAR) activation, promoting neuronal death. Despite extensive evidence from preclinical studies suggesting that excessive NMDAR stimulation during ischemic stroke is a central step in post-stroke damage, NMDAR blockers have failed to translate into clinical stroke treatment. Current treatment options for stroke are very limited, and there is therefore a great need to develop new targets for neuroprotective therapeutic agents in ischemic stroke to extend the therapeutic time window. In this review, we highlight recent findings on glutamate release, reuptake mechanisms, NMDAR and its downstream cellular signaling pathways in post-ischemic stroke damage, and review the pathological changes in each link to help develop viable new therapeutic targets. We then also summarize potential neuroprotective drugs and therapeutic approaches for these new targets in the treatment of ischemic stroke.
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Affiliation(s)
- Zihuan Shen
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China; Clinical Medical School, Beijing University of Traditional Chinese Medicine, Beijing 100029, China
| | - Mi Xiang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Chen Chen
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Fan Ding
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China; Clinical Medical School, Beijing University of Traditional Chinese Medicine, Beijing 100029, China
| | - Yuling Wang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China; Clinical Medical School, Beijing University of Traditional Chinese Medicine, Beijing 100029, China
| | - Chang Shang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China; Clinical Medical School, Beijing University of Traditional Chinese Medicine, Beijing 100029, China
| | - Laiyun Xin
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Yang Zhang
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China.
| | - Xiangning Cui
- Department of Cardiovascular, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China.
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3
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Arkhipova V, Fu H, Hoorens MWH, Trinco G, Lameijer LN, Marin E, Feringa BL, Poelarends GJ, Szymanski W, Slotboom DJ, Guskov A. Structural Aspects of Photopharmacology: Insight into the Binding of Photoswitchable and Photocaged Inhibitors to the Glutamate Transporter Homologue. J Am Chem Soc 2021; 143:1513-1520. [PMID: 33449695 PMCID: PMC7844824 DOI: 10.1021/jacs.0c11336] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
Photopharmacology addresses the challenge of drug selectivity and
side effects through creation of photoresponsive molecules activated
with light with high spatiotemporal precision. This is achieved through
incorporation of molecular photoswitches and photocages into the pharmacophore.
However, the structural basis for the light-induced modulation of
inhibitory potency in general is still missing, which poses a major
design challenge for this emerging field of research. Here we solved
crystal structures of the glutamate transporter homologue GltTk in complex with photoresponsive transport inhibitors—azobenzene
derivative of TBOA (both in trans and cis configuration) and with the photocaged compound ONB-hydroxyaspartate.
The essential role of glutamate transporters in the functioning of
the central nervous system renders them potential therapeutic targets
in the treatment of neurodegenerative diseases. The obtained structures
provide a clear structural insight into the origins of photocontrol
in photopharmacology and lay the foundation for application of photocontrolled
ligands to study the transporter dynamics by using time-resolved X-ray
crystallography.
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Affiliation(s)
- Valentina Arkhipova
- University Medical Center Groningen, Department of Radiology, Medical Imaging Center, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.,Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Haigen Fu
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Mark W H Hoorens
- University Medical Center Groningen, Department of Radiology, Medical Imaging Center, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.,Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Gianluca Trinco
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Lucien N Lameijer
- University Medical Center Groningen, Department of Radiology, Medical Imaging Center, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.,Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Egor Marin
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.,Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - Ben L Feringa
- Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Gerrit J Poelarends
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Wiktor Szymanski
- University Medical Center Groningen, Department of Radiology, Medical Imaging Center, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.,Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Dirk J Slotboom
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Albert Guskov
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.,Research Center for Molecular Mechanisms of Aging and Age-related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
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4
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Liu N, Jensen AA, Bunch L. β-Indolyloxy Functionalized Aspartate Analogs as Inhibitors of the Excitatory Amino Acid Transporters (EAATs). ACS Med Chem Lett 2020; 11:2212-2220. [PMID: 33214831 DOI: 10.1021/acsmedchemlett.0c00342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/26/2020] [Indexed: 11/28/2022] Open
Abstract
The excitatory amino acid transporters (EAATs) mediate uptake of the major excitatory neurotransmitter l-glutamate (Glu). The essential functions governed by these transporters in regulating the central Glu level make them interesting therapeutic targets in a wide range of neurodegenerative and psychiatric disorders. l-Aspartate (Asp), another EAAT substrate, has served as a privileged scaffold for the development of EAAT inhibitors. In this study, we designed and synthesized the first β-indolyloxy Asp analogs 15a-d with the aim to probe a hitherto unexplored adjacent pocket to the substrate binding site. The pharmacological properties of 15a-d were characterized at hEAAT1-3 and rEAAT4 in a conventional [3H]-d-Asp uptake assay. Notably, thiophene analog 15b and the para-trifluoromethyl phenyl analog 15d were found to be hEAAT1,2-preferring inhibitors exhibiting IC50 values in the high nanomolar range (0.21-0.71 μM) at these two transporters versus IC50 values in the low micromolar range at EAAT3,4 (1.6-8.9 μM). In summary, the results presented herein open up for further structure-activity relationship studies of this new scaffold.
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Affiliation(s)
- Na Liu
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
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5
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Braidy N, Alicajic H, Pow D, Smith J, Jugder BE, Brew BJ, Nicolazzo JA, Guillemin GJ. Potential Mechanism of Cellular Uptake of the Excitotoxin Quinolinic Acid in Primary Human Neurons. Mol Neurobiol 2020; 58:34-54. [PMID: 32894500 DOI: 10.1007/s12035-020-02046-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 07/28/2020] [Indexed: 01/18/2023]
Abstract
In Alzheimer's disease (AD), excessive amounts of quinolinic acid (QUIN) accumulate within the brain parenchyma and dystrophic neurons. QUIN also regulates glutamate uptake into neurons, which may be due to modulation of Na+-dependent excitatory amino acid transporters (EAATs). To determine the biological relationships between QUIN and glutamate dysfunction, we first quantified the functionality and kinetics of [3H]QUIN uptake in primary human neurons using liquid scintillation. We then measured changes in the protein expression of the glutamate transporter EAAT3 and EAAT1b in primary neurons treated with QUIN and the EAAT inhibitor L-trans-pyrrolidine-2,4-dicarboxylic acid (2,4-PDC) using western blotting and immunohistochemistry. Immunohistochemistry was further used to elucidate intracellular transport of exogenous QUIN and the lysosomal-associated membrane protein 2 (LAMP2). Structural insights into the binding between QUIN and EAAT3 were further investigated using molecular docking techniques. We report significant temperature-dependent high-affinity transport leading to neuronal uptake of [3H]QUIN with a Km of 42.2 μM, and a Vmax of 9.492 pmol/2 min/mg protein, comparable with the uptake of glutamate. We also found that QUIN increases expression of the EAAT3 monomer while decreasing the functional trimer. QUIN uptake into primary neurons was shown to involve EAAT3 as uptake was significantly attenuated following EAAT inhibition. We also demonstrated that QUIN increases the expression of aberrant EAAT1b protein in neurons further implicating QUIN-induced glutamate dysfunction. Furthermore, we demonstrated that QUIN is metabolised exclusively in lysosomes. The involvement of EAAT3 as a modulator for QUIN uptake was further confirmed using molecular docking. This study is the first to characterise a mechanism for QUIN uptake into primary human neurons involving EAAT3, opening potential targets to attenuate QUIN-induced excitotoxicity in neuroinflammatory diseases.
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Affiliation(s)
- Nady Braidy
- Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, Australia.
- School of Medicine, Huzhou University, Wuxing District, Huzhou, Zhejiang, China.
| | - Hayden Alicajic
- Neuropharmacology group, MND and Neurodegenerative diseases Research Centre, Macquarie University, Sydney, NSW, 2019, Australia
| | - David Pow
- University of Queensland Centre for Clinical Research, The University of Queensland, Brisbane, Queensland, Australia
| | - Jason Smith
- Department of Chemistry and Biomolecular sciences, Macquarie University, Sydney, NSW, Australia
| | - Bat-Erdene Jugder
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Bruce J Brew
- St Vincent's Centre for Applied Medical Research, Sydney, Australia
- Department of Neurology and HIV Medicine, St Vincent's Hospital, Sydney, Australia
| | - Joseph A Nicolazzo
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Australia
| | - Gilles J Guillemin
- Neuropharmacology group, MND and Neurodegenerative diseases Research Centre, Macquarie University, Sydney, NSW, 2019, Australia.
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6
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Sudha AJ, Aslam NA, Sandhu A, Yasuda M, Baba A, Babu SA. Synthesis of β-cyanoalanine and enantiomerically enriched aspartate derivatives via the Zn- or In-mediated nucleophilic addition to α-imino esters. Tetrahedron 2020. [DOI: 10.1016/j.tet.2020.131217] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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7
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Wu P, Bjørn-Yoshimoto WE, Staudt M, Jensen AA, Bunch L. Identification and Structure-Activity Relationship Study of Imidazo[1,2- a]pyridine-3-amines as First Selective Inhibitors of Excitatory Amino Acid Transporter Subtype 3 (EAAT3). ACS Chem Neurosci 2019; 10:4414-4429. [PMID: 31573179 DOI: 10.1021/acschemneuro.9b00447] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
In the present study, screening of a library of 49,087 compounds at the excitatory amino acid transporter subtype 3 (EAAT3) led to the identification of 2-(furan-2-yl)-8-methyl-N-(o-tolyl)imidazo[1,2-a]pyridin-3-amine (3a) which showed a >20-fold preference for inhibition of EAAT3 (IC50 = 13 μM) over EAAT1,2,4 (EAAT1: IC50 ∼ 250 μM; EAAT2,4: IC50 > 250 μM). It was shown that a small lipophilic substituent (methyl or bromine) at the 7- and/or 8-position was essential for activity. Furthermore, the substitution pattern of the o-tolyl group (compound 5b) and the chemical nature of the substituent in the 2-position (compound 7b) were shown to be essential for the selectivity toward EAAT3 over EAAT1,2. The most prominent analogues to come out of this study are 3a and 3e that display ∼35-fold selectivity for EAAT3 (IC50 = 7.2 μM) over EAAT1,2,4 (IC50 ∼ 250 μM).
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Affiliation(s)
- Peng Wu
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Walden E. Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Markus Staudt
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Anders A. Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2100, Denmark
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8
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Fu H, Zhang J, Tepper PG, Bunch L, Jensen AA, Poelarends GJ. Chemoenzymatic Synthesis and Pharmacological Characterization of Functionalized Aspartate Analogues As Novel Excitatory Amino Acid Transporter Inhibitors. J Med Chem 2018; 61:7741-7753. [PMID: 30011368 PMCID: PMC6139576 DOI: 10.1021/acs.jmedchem.8b00700] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
Aspartate (Asp) derivatives are privileged
compounds for investigating
the roles governed by excitatory amino acid transporters (EAATs) in
glutamatergic neurotransmission. Here, we report the synthesis of
various Asp derivatives with (cyclo)alkyloxy and (hetero)aryloxy substituents
at C-3. Their pharmacological properties were characterized at the
EAAT1–4 subtypes. The l-threo-3-substituted
Asp derivatives 13a–e and 13g–k were nonsubstrate inhibitors, exhibiting pan
activity at EAAT1–4 with IC50 values ranging from
0.49 to 15 μM. Comparisons between (dl-threo)-19a–c and (dl-erythro)-19a–c Asp analogues
confirmed that the threo configuration is crucial
for the EAAT1–4 inhibitory activities. Analogues (3b–e) of l-TFB-TBOA (3a)
were shown to be potent EAAT1–4 inhibitors, with IC50 values ranging from 5 to 530 nM. Hybridization of the nonselective
EAAT inhibitor l-TBOA with EAAT2-selective inhibitor WAY-213613
or EAAT3-preferring inhibitor NBI-59159 yielded compounds 8 and 9, respectively, which were nonselective EAAT inhibitors
displaying considerably lower IC50 values at EAAT1–4
(11–140 nM) than those displayed by the respective parent molecules.
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Affiliation(s)
- Haigen Fu
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy , University of Groningen , Antonius Deusinglaan 1 , 9713 AV Groningen , The Netherlands
| | - Jielin Zhang
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy , University of Groningen , Antonius Deusinglaan 1 , 9713 AV Groningen , The Netherlands
| | - Pieter G Tepper
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy , University of Groningen , Antonius Deusinglaan 1 , 9713 AV Groningen , The Netherlands
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences , University of Copenhagen , DK-2100 Copenhagen OE , Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences , University of Copenhagen , DK-2100 Copenhagen OE , Denmark
| | - Gerrit J Poelarends
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy , University of Groningen , Antonius Deusinglaan 1 , 9713 AV Groningen , The Netherlands
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9
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Drugs to Alter Extracellular Concentration of Glutamate: Modulators of Glutamate Uptake Systems. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/978-1-4939-7228-9_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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10
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Cheng B, Shchepakin D, Kavanaugh MP, Trauner D. Photoswitchable Inhibitor of a Glutamate Transporter. ACS Chem Neurosci 2017; 8:1668-1672. [PMID: 28414419 DOI: 10.1021/acschemneuro.7b00072] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Excitatory amino acid transporters clear glutamate from the synaptic cleft and play a critical role in glutamatergic neurotransmission. Their differential roles in astrocytes, microglia, and neurons are poorly understood due in part to a lack of pharmacological tools that can be targeted to specific cells and tissues. We now describe a photoswitchable inhibitor, termed ATT, that interacts with the major mammalian forebrain transporters EAAT1-3 in a manner that can be reversibly switched between trans (high-affinity) and cis (low-affinity) configurations using light of different colors. In the dark, ATT competitively inhibited the predominant glial transporter EAAT2 with ∼200-fold selectivity over the neuronal transporter EAAT3. Brief exposure to 350 nm light reduced the steady-state blocker affinity by more than an order of magnitude. Illumination of EAAT2 complexed with ATT induced a corresponding increase in the blocker off-rate monitored in the presence of glutamate. ATT can be used to reversibly manipulate glutamate transporter activity with light and may be useful to gain insights into the dynamic physiological roles of glutamate transporters in the brain, as well as to study the molecular interactions of transporters with ligands.
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Affiliation(s)
- Bichu Cheng
- Department
of Chemistry and Center for Integrated Protein Science (CIPSM), LMU Munich, 81377 Munich, Germany
| | - Denis Shchepakin
- University of Montana Center for Neuroscience, 32 Campus Drive, Missoula, Montana 59803, United States
| | - Michael P. Kavanaugh
- University of Montana Center for Neuroscience, 32 Campus Drive, Missoula, Montana 59803, United States
| | - Dirk Trauner
- Department
of Chemistry and Center for Integrated Protein Science (CIPSM), LMU Munich, 81377 Munich, Germany
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11
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Hansen JC, Bjørn-Yoshimoto WE, Bisballe N, Nielsen B, Jensen AA, Bunch L. β-Sulfonamido Functionalized Aspartate Analogues as Excitatory Amino Acid Transporter Inhibitors: Distinct Subtype Selectivity Profiles Arising from Subtle Structural Differences. J Med Chem 2016; 59:8771-8786. [PMID: 27636002 DOI: 10.1021/acs.jmedchem.6b01066] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In this study inspired by previous work on 3-substituted Asp analogues, we designed and synthesized a total of 32 β-sulfonamide Asp analogues and characterized their pharmacological properties at the excitatory amino acid transporter subtypes EAAT1, EAAT2, and EAAT3. In addition to several potent EAAT inhibitors displaying IC50 values ∼1 μM at all three subtypes, this elaborate structure-activity relationship also identified analogues exhibiting distinct preferences or selectivities for specific transporter subtypes. Introduction of two fluorine atoms on the phenyl ring yielded analogue 4y that displayed an IC50 of 0.8 μM at EAAT1 with a 14- and 9-fold preference over EAAT2 and EAAT3, respectively. Conversely, the m-CF3-phenyl analogue 4r was a potent selective EAAT2-inhibitor (IC50 = 2.8 μM) exhibiting 30- and 50-fold selectivity over EAAT1 and EAAT3, respectively. In conclusion, even small structural differences in these β-sulfonamide Asp analogues provide analogues with diverse EAAT subtype selectivity profiles.
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Affiliation(s)
- Jacob C Hansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Walden E Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Niels Bisballe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
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12
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Hansen SW, Erichsen MN, Fu B, Bjørn-Yoshimoto WE, Abrahamsen B, Hansen JC, Jensen AA, Bunch L. Identification of a New Class of Selective Excitatory Amino Acid Transporter Subtype 1 (EAAT1) Inhibitors Followed by a Structure-Activity Relationship Study. J Med Chem 2016; 59:8757-8770. [PMID: 27626828 DOI: 10.1021/acs.jmedchem.6b01058] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Screening of a small compound library at the three excitatory amino acid transporter subtypes 1-3 (EAAT1-3) resulted in the identification of compound (Z)-4-chloro-3-(5-((3-(2-ethoxy-2-oxoethyl)-2,4-dioxothiazolidin-5-ylidene)methyl)furan-2-yl)benzoic acid (1a) that exhibited a distinct preference as an inhibitor at EAAT1 (IC50 20 μM) compared to EAAT2 and EAAT3 (IC50 > 300 μM). This prompted us to subject 1a to an elaborate structure-activity relationship study through the purchase and synthesis and subsequent pharmacological characterization of a total of 36 analogues. Although this effort did not result in analogues with substantially improved inhibitory potencies at EAAT1 compared to that displayed by the hit, it provided a detailed insight into structural requirements for EAAT1 activity of this scaffold. The discovery of this new class of EAAT1-selective inhibitors not only supplements the currently available pharmacological tools in the EAAT field but also substantiates the notion that EAAT ligands not derived from α-amino acids hold considerable potential in terms of subtype-selective modulation of the transporters.
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Affiliation(s)
- Stinne W Hansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Mette N Erichsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Bingru Fu
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Walden E Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Bjarke Abrahamsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Jacob C Hansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
| | - Lennart Bunch
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen , Universitetsparken 2, Copenhagen Ø 2100, Denmark
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13
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Bjørn-Yoshimoto WE, Underhill SM. The importance of the excitatory amino acid transporter 3 (EAAT3). Neurochem Int 2016; 98:4-18. [PMID: 27233497 DOI: 10.1016/j.neuint.2016.05.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 05/09/2016] [Accepted: 05/17/2016] [Indexed: 12/21/2022]
Abstract
The neuronal excitatory amino acid transporter 3 (EAAT3) is fairly ubiquitously expressed in the brain, though it does not necessarily maintain the same function everywhere. It is important in maintaining low local concentrations of glutamate, where its predominant post-synaptic localization can buffer nearby glutamate receptors and modulate excitatory neurotransmission and synaptic plasticity. It is also the main neuronal cysteine uptake system acting as the rate-limiting factor for the synthesis of glutathione, a potent antioxidant, in EAAT3 expressing neurons, while on GABAergic neurons, it is important in supplying glutamate as a precursor for GABA synthesis. Several diseases implicate EAAT3, and modulation of this transporter could prove a useful therapeutic approach. Regulation of EAAT3 could be targeted at several points for functional modulation, including the level of transcription, trafficking and direct pharmacological modulation, and indeed, compounds and experimental treatments have been identified that regulate EAAT3 function at different stages, which together with observations of EAAT3 regulation in patients is giving us insight into the endogenous function of this transporter, as well as the consequences of altered function. This review summarizes work done on elucidating the role and regulation of EAAT3.
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Affiliation(s)
- Walden E Bjørn-Yoshimoto
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 København Ø, Denmark
| | - Suzanne M Underhill
- National Institute of Mental Health, National Institutes of Health, 35 Convent Drive Room 3A: 210 MSC3742, Bethesda, MD 20892-3742, USA.
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14
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Lin L, Yee SW, Kim RB, Giacomini KM. SLC transporters as therapeutic targets: emerging opportunities. Nat Rev Drug Discov 2015; 14:543-60. [PMID: 26111766 DOI: 10.1038/nrd4626] [Citation(s) in RCA: 499] [Impact Index Per Article: 55.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Solute carrier (SLC) transporters - a family of more than 300 membrane-bound proteins that facilitate the transport of a wide array of substrates across biological membranes - have important roles in physiological processes ranging from the cellular uptake of nutrients to the absorption of drugs and other xenobiotics. Several classes of marketed drugs target well-known SLC transporters, such as neurotransmitter transporters, and human genetic studies have provided powerful insight into the roles of more-recently characterized SLC transporters in both rare and common diseases, indicating a wealth of new therapeutic opportunities. This Review summarizes knowledge on the roles of SLC transporters in human disease, describes strategies to target such transporters, and highlights current and investigational drugs that modulate SLC transporters, as well as promising drug targets.
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Affiliation(s)
- Lawrence Lin
- Department of Bioengineering and Therapeutic Sciences, Schools of Pharmacy and Medicine, University of California San Francisco, San Francisco, California 94158, USA
| | - Sook Wah Yee
- Department of Bioengineering and Therapeutic Sciences, Schools of Pharmacy and Medicine, University of California San Francisco, San Francisco, California 94158, USA
| | - Richard B Kim
- Division of Clinical Pharmacology, Department of Medicine, University of Western Ontario, London Health Science Centre, London, Ontario N6A 5A5, Canada
| | - Kathleen M Giacomini
- 1] Department of Bioengineering and Therapeutic Sciences, Schools of Pharmacy and Medicine, University of California San Francisco, San Francisco, California 94158, USA. [2] Institute for Human Genetics, University of California San Francisco, San Francisco, California 94158, USA
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15
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de Villiers J, de Villiers M, Geertsema EM, Raj H, Poelarends GJ. Chemoenzymatic Synthesis of ortho-, meta-, and para-Substituted Derivatives of l- threo-3-Benzyloxyaspartate, An Important Glutamate Transporter Blocker. ChemCatChem 2015; 7:1931-1934. [PMID: 26251674 PMCID: PMC4517298 DOI: 10.1002/cctc.201500318] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Indexed: 01/13/2023]
Abstract
A simple, three-step chemoenzymatic synthesis of l-threo-3-benzyloxyaspartate (l-TBOA), as well as l-TBOA derivatives with F, CF3, and CH3 substituents at the aromatic ring, starting from dimethyl acetylenedicarboxylate was investigated. These chiral amino acids, which are extremely difficult to prepare by chemical synthesis, form an important class of inhibitors of excitatory amino acid transporters involved in the regulation of glutamatergic neurotransmission. In addition, a new chemical procedure for the synthesis of racemic mixtures of TBOA and its derivatives was explored. These chemically prepared racemates are valuable reference compounds in chiral-phase HPLC to establish the enantiopurities of the corresponding chemoenzymatically prepared amino acids.
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Affiliation(s)
- Jandré de Villiers
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands )
| | - Marianne de Villiers
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands )
| | - Edzard M Geertsema
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands )
| | - Hans Raj
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands ) ; Current address: Chr-Hansen A/S, Boge Alle 10-12 2970 Horsholm (Denmark)
| | - Gerrit J Poelarends
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands )
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16
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Wu Z, Zha Z, Li G, Lieberman BP, Choi SR, Ploessl K, Kung HF. [(18)F](2S,4S)-4-(3-Fluoropropyl)glutamine as a tumor imaging agent. Mol Pharm 2014; 11:3852-66. [PMID: 25095908 PMCID: PMC4224545 DOI: 10.1021/mp500236y] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
![]()
Although
the growth and proliferation of most tumors is fueled
by glucose, some tumors are more likely to metabolize glutamine. In
particular, tumor cells with the upregulated c-Myc gene are generally
reprogrammed to utilize glutamine. We have developed new 3-fluoropropyl
analogs of glutamine, namely [18F](2S,4R)- and [18F](2S,4S)-4-(3-fluoropropyl)glutamine, 3 and 4,
to be used as probes for studying glutamine metabolism in these tumor
cells. Optically pure isomers labeled with 18F and 19F (2S,4S) and (2S,4R)-4-(3-fluoropropyl)glutamine were synthesized via
different routes and isolated in high radiochemical purity (≥95%).
Cell uptake studies of both isomers showed that they were taken up
efficiently by 9L tumor cells with a steady increase over a time frame
of 120 min. At 120 min, their uptake was approximately two times higher
than that of l-[3H]glutamine ([3H]Gln).
These in vitro cell uptake studies suggested that the new probes are
potential tumor imaging agents. Yet, the lower chemical yield of the
precursor for 3, as well as the low radiochemical yield
for 3, limits the availability of [18F](2S,4R)-4-(3-fluoropropyl)glutamine, 3. We, therefore, focused on [18F](2S,4S)-4-(3-fluoropropyl)glutamine, 4. The in vitro cell uptake studies suggested that the new probe,
[18F](2S,4S)-4-(3-fluoropropyl)glutamine, 4, is most sensitive to the LAT transport system, followed
by System N and ASC transporters. A dual-isotope experiment using l-[3H]glutamine and the new probe showed that the
uptake of [3H]Gln into 9L cells was highly associated with
macromolecules (>90%), whereas the [18F](2S,4S)-4-(3-fluoropropyl)glutamine, 4, was not (<10%). This suggests a different mechanism of retention.
In vivo PET imaging studies demonstrated tumor-specific uptake in
rats bearing 9L xenographs with an excellent tumor to muscle ratio
(maximum of ∼8 at 40 min). [18F](2S,4S)-4-(3-fluoropropyl)glutamine, 4, may be useful for testing tumors that may metabolize glutamine
related amino acids.
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Affiliation(s)
- Zehui Wu
- Departments of Radiology and ‡Pharmacology, University of Pennsylvania , 3700 Market Street, Philadelphia, Pennsylvania 19104, United States
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17
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Carrigan CN, Patel SA, Cox HD, Bolstad ES, Gerdes JM, Smith WE, Bridges RJ, Thompson CM. The development of benzo- and naphtho-fused quinoline-2,4-dicarboxylic acids as vesicular glutamate transporter (VGLUT) inhibitors reveals a possible role for neuroactive steroids. Bioorg Med Chem Lett 2013; 24:850-4. [PMID: 24424130 DOI: 10.1016/j.bmcl.2013.12.086] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Revised: 12/17/2013] [Accepted: 12/19/2013] [Indexed: 11/19/2022]
Abstract
Substituted quinoline-2,4-dicarboxylates (QDCs) are conformationally-restricted mimics of glutamate that were previously reported to selectively block the glutamate vesicular transporters (VGLUTs). We find that expanding the QDC scaffold to benzoquinoline dicarboxylic acids (BQDC) and naphthoquinoline dicarboxylic acids (NQDCs) improves inhibitory activity with the NQDCs showing IC50∼70 μM. Modeling overlay studies showed that the polycyclic QDCs resembled steroid structures and led to the identification and testing of estrone sulfate, pregnenolone sulfate and pregnanolone sulfate that blocked the uptake of l-Glu by 50%, 70% and 85% of control, respectively. Pregnanolone sulfate was further characterized by kinetic pharmacological determinations that demonstrated competitive inhibition and a Ki of ≈20 μM.
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Affiliation(s)
- Christina N Carrigan
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Sarjubhai A Patel
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Holly D Cox
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Erin S Bolstad
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
| | - John M Gerdes
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Wesley E Smith
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Richard J Bridges
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
| | - Charles M Thompson
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA.
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18
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: transporters. Br J Pharmacol 2013; 170:1706-96. [PMID: 24528242 PMCID: PMC3892292 DOI: 10.1111/bph.12450] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Transporters are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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19
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Kanai Y, Clémençon B, Simonin A, Leuenberger M, Lochner M, Weisstanner M, Hediger MA. The SLC1 high-affinity glutamate and neutral amino acid transporter family. Mol Aspects Med 2013; 34:108-20. [PMID: 23506861 DOI: 10.1016/j.mam.2013.01.001] [Citation(s) in RCA: 216] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 12/14/2012] [Indexed: 01/07/2023]
Abstract
Glutamate transporters play important roles in the termination of excitatory neurotransmission and in providing cells throughout the body with glutamate for metabolic purposes. The high-affinity glutamate transporters EAAC1 (SLC1A1), GLT1 (SLC1A2), GLAST (SLC1A3), EAAT4 (SLC1A6), and EAAT5 (SLC1A7) mediate the cellular uptake of glutamate by the co-transport of three sodium ions (Na(+)) and one proton (H(+)), with the counter-transport of one potassium ion (K(+)). Thereby, they protect the CNS from glutamate-induced neurotoxicity. Loss of function of glutamate transporters has been implicated in the pathogenesis of several diseases, including amyotrophic lateral sclerosis and Alzheimer's disease. In addition, glutamate transporters play a role in glutamate excitotoxicity following an ischemic stroke, due to reversed glutamate transport. Besides glutamate transporters, the SLC1 family encompasses two transporters of neutral amino acids, ASCT1 (SLC1A4) and ASCT2 (SLC1A5). Both transporters facilitate electroneutral exchange of amino acids in neurons and/or cells of the peripheral tissues. Some years ago, a high resolution structure of an archaeal homologue of the SLC1 family was determined, followed by the elucidation of its structure in the presence of the substrate aspartate and the inhibitor d,l-threo-benzyloxy aspartate (d,l-TBOA). Historically, the first few known inhibitors of SLC1 transporters were based on constrained glutamate analogs which were active in the high micromolar range but often also showed off-target activity at glutamate receptors. Further development led to the discovery of l-threo-β-hydroxyaspartate derivatives, some of which effectively inhibited SLC1 transporters at nanomolar concentrations. More recently, small molecule inhibitors have been identified whose structures are not based on amino acids. Activators of SLC1 family members have also been discovered but there are only a few examples known.
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Affiliation(s)
- Yoshikatsu Kanai
- Division of Biosystem Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565 0871, Japan
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20
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Aslam NA, Babu SA, Sudha AJ, Yasuda M, Baba A. Chelation-controlled diastereoselective construction of N-aryl-, N-acyl/tosylhydrazono β-substituted aspartate derivatives via Barbier-type reaction. Tetrahedron 2013. [DOI: 10.1016/j.tet.2013.05.130] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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21
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Raj H, Szymanski W, de Villiers J, Puthan Veetil V, Quax WJ, Shimamoto K, Janssen DB, Feringa BL, Poelarends GJ. Kinetic resolution and stereoselective synthesis of 3-substituted aspartic acids by using engineered methylaspartate ammonia lyases. Chemistry 2013; 19:11148-52. [PMID: 23852946 DOI: 10.1002/chem.201301832] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Indexed: 12/20/2022]
Abstract
Enzymatic amino acid synthesis: Kinetic resolution and asymmetric synthesis of various valuable 3-substituted aspartic acids, which were obtained in fair to good yields with diastereomeric ratio values of up to >98:2 and enantiomeric excess values of up to >99 %, by using engineered methylaspartate ammonia lyases are described. These biocatalytic methodologies for the selective preparation of aspartic acid derivatives appear to be attractive alternatives for existing chemical methods.
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Affiliation(s)
- Hans Raj
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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22
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Bridges RJ, Natale NR, Patel SA. System xc⁻ cystine/glutamate antiporter: an update on molecular pharmacology and roles within the CNS. Br J Pharmacol 2012; 165:20-34. [PMID: 21564084 DOI: 10.1111/j.1476-5381.2011.01480.x] [Citation(s) in RCA: 353] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
System x(c)(-) is an amino acid antiporter that typically mediates the exchange of extracellular l-cystine and intracellular L-glutamate across the cellular plasma membrane. Studied in a variety of cell types, the import of L-cystine through this transporter is critical to glutathione production and oxidative protection. The exchange-mediated export of L-glutamate takes on added significance within the CNS, as it represents a non-vesicular route of release through which this excitatory neurotransmitter can participate in either neuronal signalling or excitotoxic pathology. When both the import of L-cystine and the export of L-glutamate are taken into consideration, system x(c)(-) has now been linked to a wide range of CNS functions, including oxidative protection, the operation of the blood-brain barrier, neurotransmitter release, synaptic organization, viral pathology, drug addiction, chemosensitivity and chemoresistance, and brain tumour growth. The ability to selectively manipulate system x(c)(-), delineate its function, probe its structure and evaluate it as a therapeutic target is closely linked to understanding its pharmacology and the subsequent development of selective inhibitors and substrates. Towards that goal, this review will examine the current status of our understanding of system x(c)(-) pharmacology and the structure-activity relationships that have guided the development of an initial pharmacophore model, including the presence of lipophilic domains adjacent to the substrate binding site. A special emphasis is placed on the roles of system x(c)(-) within the CNS, as it is these actions that are among the most exciting as potential long-range therapeutic targets.
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Affiliation(s)
- Richard J Bridges
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana 59812, USA.
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23
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Engineering methylaspartate ammonia lyase for the asymmetric synthesis of unnatural amino acids. Nat Chem 2012; 4:478-84. [PMID: 22614383 DOI: 10.1038/nchem.1338] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 03/21/2012] [Indexed: 12/11/2022]
Abstract
The redesign of enzymes to produce catalysts for a predefined transformation remains a major challenge in protein engineering. Here, we describe the structure-based engineering of methylaspartate ammonia lyase (which in nature catalyses the conversion of 3-methylaspartate to ammonia and 2-methylfumarate) to accept a variety of substituted amines and fumarates and catalyse the asymmetric synthesis of aspartic acid derivatives. We obtained two single-active-site mutants, one exhibiting a wide nucleophile scope including structurally diverse linear and cyclic alkylamines and one with broad electrophile scope including fumarate derivatives with alkyl, aryl, alkoxy, aryloxy, alkylthio and arylthio substituents at the C2 position. Both mutants have an enlarged active site that accommodates the new substrates while retaining the high stereo- and regioselectivity of the wild-type enzyme. As an example, we demonstrate a highly enantio- and diastereoselective synthesis of threo-3-benzyloxyaspartate (an important inhibitor of neuronal excitatory glutamate transporters in the brain).
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24
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Specificity and actions of an arylaspartate inhibitor of glutamate transport at the Schaffer collateral-CA1 pyramidal cell synapse. PLoS One 2011; 6:e23765. [PMID: 21887314 PMCID: PMC3161057 DOI: 10.1371/journal.pone.0023765] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 07/25/2011] [Indexed: 01/15/2023] Open
Abstract
In this study we characterized the pharmacological selectivity and physiological actions of a new arylaspartate glutamate transporter blocker, L-threo-ß-benzylaspartate (L-TBA). At concentrations up to 100 µM, L-TBA did not act as an AMPA receptor (AMPAR) or NMDA receptor (NMDAR) agonist or antagonist when applied to outside-out patches from mouse hippocampal CA1 pyramidal neurons. L-TBA had no effect on the amplitude of field excitatory postsynaptic potentials (fEPSPs) recorded at the Schaffer collateral-CA1 pyramidal cell synapse. Excitatory postsynaptic currents (EPSCs) in CA1 pyramidal neurons were unaffected by L-TBA in the presence of physiological extracellular Mg2+ concentrations, but in Mg2+-free solution, EPSCs were significantly prolonged as a consequence of increased NMDAR activity. Although L-TBA exhibited approximately four-fold selectivity for neuronal EAAT3 over glial EAAT1/EAAT2 transporter subtypes expressed in Xenopus oocytes, the L-TBA concentration-dependence of the EPSC charge transfer increase in the absence of Mg2+ was the same in hippocampal slices from EAAT3 +/+ and EAAT3 −/− mice, suggesting that TBA effects were primarily due to block of glial transporters. Consistent with this, L-TBA blocked synaptically evoked transporter currents in CA1 astrocytes with a potency in accord with its block of heterologously expressed glial transporters. Extracellular recording in the presence of physiological Mg2+ revealed that L-TBA prolonged fEPSPs in a frequency-dependent manner by selectively increasing the NMDAR-mediated component of the fEPSP during short bursts of activity. The data indicate that glial glutamate transporters play a dominant role in limiting extrasynaptic transmitter diffusion and binding to NMDARs. Furthermore, NMDAR signaling is primarily limited by voltage-dependent Mg2+ block during low-frequency activity, while the relative contribution of transport increases during short bursts of higher frequency signaling.
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25
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Mekki S, Rolland V, Bellahouel S, van der Lee A, Rolland M. Concomitant polymorphism in the stereoselective synthesis of a β-benzyl-β-hydroxyaspartate analogue. Acta Crystallogr C 2011; 67:o301-5. [PMID: 21817797 DOI: 10.1107/s0108270111024632] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 06/22/2011] [Indexed: 11/10/2022] Open
Abstract
Two concomitant polymorphs, (I) and (II), of a β-benzyl-β-hydroxyaspartate analogue [systematic name: dibenzyl 2-benzyl-2-hydroxy-3-(4-methylphenylsulfonamido)succinate], C(32)H(31)NO(7)S, crystallize from a mixture of ethyl acetate and cyclohexane at ambient temperature. The structure of (I) has triclinic (P-1) symmetry and that of (II) monoclinic (P2(1)/c) symmetry. Both crystal structures are made up of a stacking of homochiral racemic dimers (2S,3S and 2R,3R) which are internally connected by a similar R(2)(2)(9) hydrogen-bonding pattern consisting of intermolecular N-H...O and O-H...O hydrogen bonds. The centroid of the racemic dimer lies on an inversion centre. The main structural difference between the two polymorphs is the conformational orientation of two of the four aromatic rings present in the molecule. Polymorph (II) is found to be twinned by reticular merohedry with twin index 3 and twin fractions 0.854 (1) and 0.146 (1).
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Affiliation(s)
- Sofiane Mekki
- Laboratoire de Synthèse Organique Appliquée, Université d'Oran Es-Sénia, Département de Chimie, Oran, Algeria
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26
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Pathmajeyan MS, Patel SA, Carroll JA, Seib T, Striebel JF, Bridges RJ, Chesebro B. Increased excitatory amino acid transport into murine prion protein knockout astrocytes cultured in vitro. Glia 2011; 59:1684-94. [PMID: 21766339 DOI: 10.1002/glia.21215] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Accepted: 06/16/2011] [Indexed: 11/06/2022]
Abstract
Prion protein (PrP) is expressed on a wide variety of cells and plays an important role in the pathogenesis of transmissible spongiform encephalopathies. However, its normal function remains unclear. Mice that do not express PrP exhibit deficits in spatial memory and abnormalities in excitatory neurotransmission suggestive that PrP may function in the glutamatergic synapse. Here, we show that transport of D-aspartate, a nonmetabolized L-glutamate analog, through excitatory amino acid transporters (EAATs) was faster in astrocytes from PrP knockout (PrPKO) mice than in astrocytes from C57BL/10SnJ wild-type (WT) mice. Experiments using EAAT subtype-specific inhibitors demonstrated that in both WT and PrPKO astrocytes, the majority of transport was mediated by EAAT1. Furthermore, PrPKO astrocytes were more effective than WT astrocytes at alleviating L-glutamate-mediated excitotoxic damage in both WT and PrPKO neuronal cultures. Thus, in this in vitro model, PrPKO astrocytes exerted a functional influence on neuronal survival and may therefore influence regulation of glutamatergic neurotransmission in vivo.
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Affiliation(s)
- Melissa S Pathmajeyan
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, NIAID, National Institute of Health, Hamilton, Montana, USA
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27
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Stutz B, Yamasaki EN, de Mello MCF, de Mello FG. Exchange of extracellular l-glutamate by intracellular d-aspartate: The main mechanism of d-aspartate release in the avian retina. Neurochem Int 2011; 58:767-75. [DOI: 10.1016/j.neuint.2011.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 01/18/2011] [Accepted: 03/02/2011] [Indexed: 10/18/2022]
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28
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Ahmed SK, Etoga JLG, Patel SA, Bridges RJ, Thompson CM. Use of the hydantoin isostere to produce inhibitors showing selectivity toward the vesicular glutamate transporter versus the obligate exchange transporter system x(c)(-). Bioorg Med Chem Lett 2011; 21:4358-62. [PMID: 21669531 DOI: 10.1016/j.bmcl.2011.05.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 05/04/2011] [Accepted: 05/06/2011] [Indexed: 12/20/2022]
Abstract
Evidence was acquired prior to suggest that the vesicular glutamate transporter (VGLUT) but not other glutamate transporters were inhibited by structures containing a weakly basic α-amino group. To test this hypothesis, a series of analogs using a hydantoin (pK(a)∼9.1) isostere were synthesized and analyzed as inhibitors of VGLUT and the obligate cystine-glutamate transporter (system x(c)(-)). Of the hydantoin analogs tested, a thiophene-5-carboxaldehyde analog 2l and a bis-hydantoin 4b were relatively strong inhibitors of VGLUT reducing uptake to less than 6% of control at 5mM but few inhibited system x(c)(-) greater than 50% of control. The benzene-2,4-disulfonic acid analog 2b and p-diaminobenzene analog 2e were also good hydantoin-based inhibitors of VGLUT reducing uptake by 11% and 23% of control, respectively, but neither analog was effective as a system x(c)(-) inhibitor. In sum, a hydantoin isostere adds the requisite chemical properties needed to produce selective inhibitors of VGLUT.
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Affiliation(s)
- S Kaleem Ahmed
- Core Laboratory for Neuromolecular Production, Department of Biomedical and Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
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Luethi E, Nguyen KT, Bürzle M, Blum LC, Suzuki Y, Hediger M, Reymond JL. Identification of selective norbornane-type aspartate analogue inhibitors of the glutamate transporter 1 (GLT-1) from the chemical universe generated database (GDB). J Med Chem 2010; 53:7236-50. [PMID: 20812729 DOI: 10.1021/jm100959g] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A variety of conformationally constrained aspartate and glutamate analogues inhibit the glutamate transporter 1 (GLT-1, also known as EAAT2). To expand the search for such analogues, a virtual library of aliphatic aspartate and glutamate analogues was generated starting from the chemical universe database GDB-11, which contains 26.4 million possible molecules up to 11 atoms of C, N, O, F, resulting in 101026 aspartate analogues and 151285 glutamate analogues. Virtual screening was realized by high-throughput docking to the glutamate binding site of the glutamate transporter homologue from Pyrococcus horikoshii (PDB code: 1XFH ) using Autodock. Norbornane-type aspartate analogues were selected from the top-scoring virtual hits and synthesized. Testing and optimization led to the identification of (1R*,2R*,3S*,4R*,6R*)-2-amino-6-phenethyl-bicyclo[2.2.1]heptane-2,3-dicarboxylic acid as a new inhibitor of GLT-1 with IC(50) = 1.4 μM against GLT-1 and no inhibition of the related transporter EAAC1. The systematic diversification of known ligands by enumeration with help of GDB followed by virtual screening, synthesis, and testing as exemplified here provides a general strategy for drug discovery.
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Affiliation(s)
- Erika Luethi
- Department of Chemistry and Biochemistry, University of Berne, Freiestrasse 3, 3012 Berne, Switzerland
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Ye R, Rhoderick JF, Thompson CM, Bridges RJ. Functional expression, purification and high sequence coverage mass spectrometric characterization of human excitatory amino acid transporter EAAT2. Protein Expr Purif 2010; 74:49-59. [PMID: 20399272 DOI: 10.1016/j.pep.2010.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/08/2010] [Accepted: 04/09/2010] [Indexed: 11/30/2022]
Abstract
The glial excitatory amino acid transporter 2 (EAAT2) mediates a majority of glutamate re-uptake in human CNS and, consequently, is associated with a variety of signaling and pathological processes. While our understanding of the function, mechanism and structure of this integral membrane protein is increasing, little if any mass spectrometric (MS) data is available for any of the EAATs specifically, and for only a few mammalian plasma membrane transporters in general. A protocol to express and purify functional EAAT2 in sufficient quantities to carry out MS-based peptide mapping as needed to study ligand-transporter interactions is described. A 6xHIS epitope was incorporated into the N-terminus of human EAAT2. The recombinant protein was expressed in high levels in mammalian HEK 293T cells, where it exhibited the pharmacological properties of the native transporter. EAAT2 was purified from isolated cell membranes in a single step using nickel affinity chromatography. In-gel and in-solution trypsin digestions were conducted on the isolated protein and then analyzed by MALDI-TOF and LC-MS/MS mass spectrometry. Overall, 89% sequence coverage of the protein was achieved with these methods. In particular, an 88 amino acid tryptic peptide covering the presumed substrate binding domains HP1, TMD7, HP2, and TMD8 domains of EAAT2 was also identified after N-deglycosylation. Beyond the specific applicability to EAAT2, this study provides an efficient, simple and scalable approach to express, purify, digest and characterize integral membrane transporter proteins by mass spectrometry.
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Affiliation(s)
- Ran Ye
- Center for Structural and Functional Neuroscience, Department of Chemistry and Biochemistry, The University of Montana, Missoula, MT 59812, USA
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31
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Foster DJ, Heacock AM, Fisher SK. Muscarinic receptor stimulation of D-aspartate uptake into human SH-SY5Y neuroblastoma cells is attenuated by hypoosmolarity. J Pharmacol Exp Ther 2010; 333:297-309. [PMID: 20080957 DOI: 10.1124/jpet.109.164277] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In addition to its function as an excitatory neurotransmitter, glutamate plays a major role as an osmolyte within the central nervous system (CNS). Accordingly, mechanisms that regulate glutamate release and uptake are of physiological importance not only during conditions in which cell volume remains constant but also when cells are subjected to hypoosmotic stress. In the present study, the ability of muscarinic cholinergic receptors (mAChRs) to regulate the uptake of glutamate (monitored as D-aspartate) into human SH-SY5Y neuroblastoma cells under isotonic or hypotonic conditions has been examined. In isotonic media, agonist activation of mAChRs resulted in a significant increase (250-300% of control) in the uptake of D-aspartate and, concurrently, a cellular redistribution of the excitatory amino acid transporter 3 (EAAT3) to the plasma membrane. mAChR-mediated increases in d-aspartate uptake were potently blocked by the EAAT3 inhibitor l-beta-threo-benzyl-aspartate. In hypotonic media, the ability of mAChR activation to facilitate D-aspartate uptake was significantly attenuated (40-50%), and the cellular distribution of EAAT3 was disrupted. Reduction of mAChR-stimulated D-aspartate uptake under hypoosmotic conditions could be fully reversed upon re-exposure of the cells to isotonic media. Under both isotonic and hypotonic conditions, mAChR-mediated increases in D-aspartate uptake depended on cytoskeletal integrity, protein kinase C and phosphatidylinositol 3-kinase activities, and the availability of intracellular Ca2+. In contrast, dependence on extracellular Ca2+ was observed only under isotonic conditions. The results suggest that, although the uptake of D-aspartate into SH-SY5Y cells is enhanced after mAChR activation, this process is markedly attenuated by hypoosmolarity.
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Affiliation(s)
- Daniel J Foster
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
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Patel SA, Rajale T, O'Brien E, Burkhart DJ, Nelson JK, Twamley B, Blumenfeld A, Szabon-Watola MI, Gerdes JM, Bridges RJ, Natale NR. Isoxazole analogues bind the system xc- transporter: structure-activity relationship and pharmacophore model. Bioorg Med Chem 2010; 18:202-13. [PMID: 19932968 PMCID: PMC2967674 DOI: 10.1016/j.bmc.2009.11.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2009] [Revised: 10/30/2009] [Accepted: 11/02/2009] [Indexed: 11/17/2022]
Abstract
Analogues of amino methylisoxazole propionic acid (AMPA), were prepared from a common intermediate 12, including lipophilic analogues using lateral metalation and electrophilic quenching, and were evaluated at System xc-. Both the 5-naphthylethyl-(16) and 5-naphthylmethoxymethyl-(17) analogues adopt an E-conformation in the solid state, yet while the former has robust binding at System xc-, the latter is virtually devoid of activity. The most potent analogues were amino acid naphthyl-ACPA 7g, and hydrazone carboxylic acid, 11e Y=Y'=3,5-(CF(3))(2), which both inhibited glutamate uptake by the System xc- transporter with comparable potency to the endogenous substrate cystine, whereas in contrast the closed isoxazolo[3,4-d] pyridazinones 13 have significantly lower activity. A preliminary pharmacophore model has been constructed to provide insight into the analogue structure-activity relationships.
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Affiliation(s)
- Sarjubhai A Patel
- NIH COBRE Center for Structural and Functional Neuroscience, The University of Montana, Missoula, MT 59812, USA
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TRANSPORTERS. Br J Pharmacol 2009. [DOI: 10.1111/j.1476-5381.2009.00505.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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35
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Glutamate (excitatory amino acid) transporters. Br J Pharmacol 2009. [DOI: 10.1111/j.1476-5381.2009.00505_6.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Bunch L, Erichsen MN, Jensen AA. Excitatory amino acid transporters as potential drug targets. Expert Opin Ther Targets 2009; 13:719-31. [DOI: 10.1517/14728220902926127] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Grewer C, Gameiro A, Zhang Z, Tao Z, Braams S, Rauen T. Glutamate forward and reverse transport: from molecular mechanism to transporter-mediated release after ischemia. IUBMB Life 2008; 60:609-19. [PMID: 18543277 DOI: 10.1002/iub.98] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Glutamate transporters remove the excitatory neurotransmitter glutamate from the extracellular space after neurotransmission is complete, by taking glutamate up into neurons and glia cells. As thermodynamic machines, these transporters can also run in reverse, releasing glutamate into the extracellular space. Because glutamate is excitotoxic, this transporter-mediated release is detrimental to the health of neurons and axons, and it, thus, contributes to the brain damage that typically follows a stroke. This review highlights current ideas about the molecular mechanisms underlying glutamate uptake and glutamate reverse transport. It also discusses the implications of transporter-mediated glutamate release for cellular function under physiological and patho-physiological conditions.
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Affiliation(s)
- Christof Grewer
- Binghamton University, Department of Chemistry, Binghamton, NY 13902, USA.
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Mavencamp TL, Rhoderick JF, Bridges RJ, Esslinger CS. Synthesis and preliminary pharmacological evaluation of novel derivatives of L-beta-threo-benzylaspartate as inhibitors of the neuronal glutamate transporter EAAT3. Bioorg Med Chem 2008; 16:7740-8. [PMID: 18650095 DOI: 10.1016/j.bmc.2008.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 07/01/2008] [Accepted: 07/02/2008] [Indexed: 10/21/2022]
Abstract
A series of beta-benzylaspartate derivatives were prepared from N-trityl-L-aspartate dimethyl ester and evaluated as inhibitors of neuronal glutamate transporter EAAT3. The result of the structure-activity studies suggests that the position occupied by the aromatic ring of beta-benzylaspartate within the binding site of EAAT3 may be different from that occupied by comparable groups in previously identified inhibitors, such as L-threo-benzyloxy aspartate (TBOA). Further, halogen substitutions at the 3-position of the aromatic ring of beta-benzylaspartate can increase the potency with which the analogues inhibit EAAT3.
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Affiliation(s)
- Terri L Mavencamp
- NIH-COBRE Center for Structural and Functional Neuroscience, Department of Biomedical & Pharmaceutical Sciences, The University of Montana, Missoula, MT 59812, USA
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Napier S, Bingham M. Pharmacology of Glutamate Transport in the CNS: Substrates and Inhibitors of Excitatory Amino Acid Transporters (EAATs) and the Glutamate/Cystine Exchanger System x c −. TOPICS IN MEDICINAL CHEMISTRY 2008. [PMCID: PMC7123079 DOI: 10.1007/7355_2008_026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
As the primary excitatory neurotransmitter in the mammalian CNS, l-glutamateparticipates not only in standard fast synaptic communication, but also contributes to higher order signalprocessing, as well as neuropathology. Given this variety of functional roles, interest has been growingas to how the extracellular concentrations of l-glutamate surroundingneurons are regulated by cellular transporter proteins. This review focuses on two prominent systems, eachof which appears capable of influencing both the signaling and pathological actions of l-glutamatewithin the CNS: the sodium-dependent excitatory amino acid transporters (EAATs) and the glutamate/cystineexchanger, system xc−(Sxc−). Whilethe family of EAAT subtypes limit access to glutamate receptors by rapidly and efficiently sequesteringl-glutamate in neurons and glia, Sxc−provides a route for the export of glutamate from cells into the extracellular environment. The primaryintent of this work is to provide an overview of the inhibitors and substrates that have been developedto delineate the pharmacological specificity of these transport systems, as well as be exploited as probeswith which to selectively investigate function. Particular attention is paid to the development of smallmolecule templates that mimic the structural properties of the endogenous substrates, l-glutamate,l-aspartate and l-cystine andhow strategic control of functional group position and/or the introduction of lipophilic R-groups can impactmultiple aspects of the transport process, including: subtype selectivity, inhibitory potency, and substrateactivity.
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Nieoullon A, Canolle B, Masmejean F, Guillet B, Pisano P, Lortet S. The neuronal excitatory amino acid transporter EAAC1/EAAT3: does it represent a major actor at the brain excitatory synapse? J Neurochem 2006; 98:1007-18. [PMID: 16800850 DOI: 10.1111/j.1471-4159.2006.03978.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
EAAC1/EAAT3 is a transporter of glutamate (Glu) present at the post-synaptic neuronal element, in opposition to the two other main transporters, GLAST/EAAT1 and GLT1/EAAT2, expressed at the excitatory amino acid (EAA) synapse by surrounding astrocytes. Although, in the adult, EAAC1/EAAT3 exhibits a rather low expression level and is considered to make a minor contribution to Glu removal from the synapse, its early expression during brain development, before the astrocytes are functional, suggests that such a neuronal transporter is involved in the developmental effects of EAA and, possibly, in the biosynthesis and trophic role of GABA, which is excitatory in nature in different brain regions during the earlier stages of brain development. This neuronal Glu transporter is considered to have a dual action as it is apparently involved in the neuronal uptake of cysteine, which acts as a key substrate for the synthesis of glutathione, a major anti-oxidant, because the neurones do not express the Xc(-) transport system in the mature brain. Interestingly, EAAC1/EAAT3 activity/expression was shown to be highly regulated by neuronal activity as well as by intracellular signalling pathways involving primarily alpha protein kinase C (alphaPKC) and phosphatidylinositol-3-kinase (PI3K). Such regulatory processes could act either at the post-traductional level or at the transcriptional level. It is worth noting that EAAC1/EAAT3 exhibits specificity, compared with other EAA transporters, because it is present mainly in the intracellular compartment and only for about 20% at the plasma membrane. Variations in neuronal Glu uptake were shown to be associated with rapid changes in the trafficking of the transporter protein altering the membranar location of the transporter. More recent data show that astrocyte-secreted factors such as cholesterol could also influence rapid changes in the location of EAAC1/EAAT3 between the plasma membrane and the cytoplasmic compartment. Such a highly regulated process of EAAC1/EAAT3 activity/expression may have implications in the physiopathology of major diseases affecting EAA brain signalling, which is further supported by data obtained in animal models of hypoxia-anoxia, for example.
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Affiliation(s)
- André Nieoullon
- IBDML-IC2N, UMR 6216 CNRS, Université de la Méditerranée, Institut de Biologie du Développement de Marseille-Luminy, Marseille, France.
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