1
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Bhatt M, Lazzarin E, Alberto-Silva AS, Domingo G, Zerlotti R, Gradisch R, Bazzone A, Sitte HH, Stockner T, Bossi E. Unveiling the crucial role of betaine: modulation of GABA homeostasis via SLC6A1 transporter (GAT1). Cell Mol Life Sci 2024; 81:269. [PMID: 38884791 DOI: 10.1007/s00018-024-05309-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 06/04/2024] [Accepted: 06/06/2024] [Indexed: 06/18/2024]
Abstract
Betaine is an endogenous osmolyte that exhibits therapeutic potential by mitigating various neurological disorders. However, the underlying cellular and molecular mechanisms responsible for its neuroprotective effects remain puzzling.In this study, we describe a possible mechanism behind the positive impact of betaine in preserving neurons from excitotoxicity. Here we demonstrate that betaine at low concentration modulates the GABA uptake by GAT1 (slc6a1), the predominant GABA transporter in the central nervous system. This modulation occurs through the temporal inhibition of the transporter, wherein prolonged occupancy by betaine impedes the swift transition of the transporter to the inward conformation. Importantly, the modulatory effect of betaine on GAT1 is reversible, as the blocking of GAT1 disappears with increased extracellular GABA. Using electrophysiology, mass spectroscopy, radiolabelled cellular assay, and molecular dynamics simulation we demonstrate that betaine has a dual role in GAT1: at mM concentration acts as a slow substrate, and at µM as a temporal blocker of GABA, when it is below its K0.5. Given this unique modulatory characteristic and lack of any harmful side effects, betaine emerges as a promising neuromodulator of the inhibitory pathways improving GABA homeostasis via GAT1, thereby conferring neuroprotection against excitotoxicity.
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Affiliation(s)
- Manan Bhatt
- Department of Biotechnology and Life Science, Laboratory of Cellular and Molecular Physiology, University of Insubria, Via J. H. Dunant 3, 21100, Varese, Italy
| | - Erika Lazzarin
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090, Vienna, Austria
| | - Ana Sofia Alberto-Silva
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090, Vienna, Austria
| | - Guido Domingo
- Department of Biotechnology and Life Science, Laboratory of Cellular and Molecular Physiology, University of Insubria, Via J. H. Dunant 3, 21100, Varese, Italy
| | - Rocco Zerlotti
- Nanion Technologies GmbH, Ganghoferstr. 70a, 80339, Munich, Germany
| | - Ralph Gradisch
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Andre Bazzone
- Nanion Technologies GmbH, Ganghoferstr. 70a, 80339, Munich, Germany
| | - Harald H Sitte
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090, Vienna, Austria
- Hourani Center for Applied Scientific Research, Al-Ahliyya Amman University, Amman, 19328, Jordan
- Center for Addiction Research and Science, Medical University of Vienna, 1090, Vienna, Austria
| | - Thomas Stockner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090, Vienna, Austria
| | - Elena Bossi
- Department of Biotechnology and Life Science, Laboratory of Cellular and Molecular Physiology, University of Insubria, Via J. H. Dunant 3, 21100, Varese, Italy.
- Centre for Neuroscience, University of Insubria, 21100, Varese, Italy.
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2
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Xie J, Long ZQ, Chen AQ, Ding YG, Liu ST, Zhou X, Liu LW, Yang S. Novel Sulfonamide Derivatives Containing a Piperidine Moiety as New Bactericide Leads for Managing Plant Bacterial Diseases. Int J Mol Sci 2023; 24:ijms24065861. [PMID: 36982936 PMCID: PMC10054644 DOI: 10.3390/ijms24065861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 03/15/2023] [Accepted: 03/16/2023] [Indexed: 03/30/2023] Open
Abstract
Plant bacterial diseases are an intractable problem due to the fact that phytopathogens have acquired strong resistances for traditional pesticides, resulting in restricting the quality and yield of agricultural products around the world. To develop new agrochemical alternatives, we prepared a novel series of sulfanilamide derivatives containing piperidine fragments and assessed their antibacterial potency. The bioassay results revealed that most molecules displayed excellent in vitro antibacterial potency towards Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas axonopodis pv. citri (Xac). In particular, molecule C4 exhibited outstanding inhibitory activity toward Xoo with EC50 value of 2.02 µg mL-1, which was significantly better than those of the commercial agents bismerthiazol (EC50 = 42.38 µg mL-1) and thiodiazole copper (EC50 = 64.50 µg mL-1). A series of biochemical assays confirmed that compound C4 interacted with dihydropteroate synthase, and irreversibly damaged the cell membrane. In vivo assays showed that the molecule C4 presented acceptable curative and protection activities of 34.78% and 39.83%, respectively, at 200 µg mL-1, which were greater than those of thiodiazole and bismerthiazol. This study highlights the valuable insights for the excavation and development of new bactericides that can concurrently target dihydropteroate synthase and bacterial cell membranes.
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Affiliation(s)
- Jiao Xie
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Zhou-Qing Long
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Ai-Qun Chen
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Ying-Guo Ding
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Shi-Tao Liu
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Xiang Zhou
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Li-Wei Liu
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
| | - Song Yang
- National Key Laboratory of Green Pesticide, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Center for R&D of Fine Chemicals of Guizhou University, Guiyang 550025, China
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3
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Pukale DD, Farrag M, Gudneppanavar R, Baumann HJ, Konopka M, Shriver LP, Leipzig ND. Osmoregulatory Role of Betaine and Betaine/γ-Aminobutyric Acid Transporter 1 in Post-Traumatic Syringomyelia. ACS Chem Neurosci 2021; 12:3567-3578. [PMID: 34550670 DOI: 10.1021/acschemneuro.1c00056] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Syringomyelia (SM) is primarily characterized by the formation of a fluid-filled cyst that forms in the parenchyma of the spinal cord following injury or other pathology. Recent omics studies in animal models have identified dysregulation of solute carriers, channels, transporters, and small molecules associated with osmolyte regulation during syrinx formation/expansion in the spinal cord. However, their connections to syringomyelia etiology are poorly understood. In this study, the biological functions of the potent osmolyte betaine and its associated solute carrier betaine/γ-aminobutyric acid (GABA) transporter 1 (BGT1) were studied in SM. First, a rat post-traumatic SM model was used to demonstrate that the BGT1 was primarily expressed in astrocytes in the vicinity of syrinxes. In an in vitro system, we found that astrocytes uptake betaine through BGT1 to regulate cell size under hypertonic conditions. Treatment with BGT1 inhibitors, especially NNC 05-2090, demonstrated midhigh micromolar range potency in vitro that reversed the osmoprotective effects of betaine. Finally, the specificity of these BGT1 inhibitors in the CNS was demonstrated in vivo, suggesting feasibility for targeting betaine transport in SM. In summary, these data provide an enhanced understanding of the role of betaine and its associated solute carrier BGT1 in cell osmoregulation and implicates the active role of betaine and BGT1 in syringomyelia progression.
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Affiliation(s)
- Dipak D. Pukale
- Department of Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, Ohio 44325, United States
| | - Mahmoud Farrag
- Integrated Biosciences Program, University of Akron, Akron, Ohio 44325, United States
| | | | - Hannah J. Baumann
- Department of Chemistry, University of Akron, Akron, Ohio 44325, United States
| | - Michael Konopka
- Department of Chemistry, University of Akron, Akron, Ohio 44325, United States
| | - Leah P. Shriver
- Integrated Biosciences Program, University of Akron, Akron, Ohio 44325, United States
- Department of Chemistry, University of Akron, Akron, Ohio 44325, United States
| | - Nic D. Leipzig
- Department of Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, Ohio 44325, United States
- Integrated Biosciences Program, University of Akron, Akron, Ohio 44325, United States
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4
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Kickinger S, Lie MEK, Suemasa A, Al-Khawaja A, Fujiwara K, Watanabe M, Wilhelmsen KS, Falk-Petersen CB, Frølund B, Shuto S, Ecker GF, Wellendorph P. Molecular Determinants and Pharmacological Analysis for a Class of Competitive Non-transported Bicyclic Inhibitors of the Betaine/GABA Transporter BGT1. Front Chem 2021; 9:736457. [PMID: 34595152 PMCID: PMC8476755 DOI: 10.3389/fchem.2021.736457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 08/30/2021] [Indexed: 11/17/2022] Open
Abstract
The betaine/GABA transporter 1 (BGT1) is a member of the GABA transporter (GAT) family with still elusive function, largely due to a lack of potent and selective tool compounds. Based on modeling, we here present the design, synthesis and pharmacological evaluation of five novel conformationally restricted cyclic GABA analogs related to the previously reported highly potent and selective BGT1 inhibitor (1S,2S,5R)-5-aminobicyclo[3.1.0]hexane-2-carboxylic acid (bicyclo-GABA). Using [3H]GABA radioligand uptake assays at the four human GATs recombinantly expressed in mammalian cell lines, we identified bicyclo-GABA and its N-methylated analog (2) as the most potent and selective BGT1 inhibitors. Additional pharmacological characterization in a fluorescence-based membrane potential assay showed that bicyclo-GABA and 2 are competitive inhibitors, not substrates, at BGT1, which was validated by a Schild analysis for bicyclo-GABA (pKB value of 6.4). To further elaborate on the selectivity profile both compounds were tested at recombinant α1β2γ2 GABAA receptors. Whereas bicyclo-GABA showed low micromolar agonistic activity, the N-methylated 2 was completely devoid of activity at GABAA receptors. To further reveal the binding mode of bicyclo-GABA and 2 binding hypotheses of the compounds were obtained from in silico-guided mutagenesis studies followed by pharmacological evaluation at selected BGT1 mutants. This identified the non-conserved BGT1 residues Q299 and E52 as the molecular determinants driving BGT1 activity and selectivity. The binding mode of bicyclo-GABA was further validated by the introduction of activity into the corresponding GAT3 mutant L314Q (38 times potency increase cf. wildtype). Altogether, our data reveal the molecular determinants for the activity of bicyclic GABA analogs, that despite their small size act as competitive inhibitors of BGT1. These compounds may serve as valuable tools to selectively and potently target BGT1 in order to decipher its elusive pharmacological role in the brain and periphery such as the liver and kidneys.
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Affiliation(s)
- Stefanie Kickinger
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Pharmaceutical Science, University of Vienna, Vienna, Austria
| | - Maria E K Lie
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Akihiro Suemasa
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Anas Al-Khawaja
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Koichi Fujiwara
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Mizuki Watanabe
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Kristine S Wilhelmsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christina B Falk-Petersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bente Frølund
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Satoshi Shuto
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Gerhard F Ecker
- Department of Pharmaceutical Science, University of Vienna, Vienna, Austria
| | - Petrine Wellendorph
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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5
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Colas C. Toward a Systematic Structural and Functional Annotation of Solute Carriers Transporters-Example of the SLC6 and SLC7 Families. Front Pharmacol 2020; 11:1229. [PMID: 32973497 PMCID: PMC7466448 DOI: 10.3389/fphar.2020.01229] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 07/28/2020] [Indexed: 12/12/2022] Open
Abstract
SLC transporters are emerging key drug targets. One important step for drug development is the profound understanding of the structural determinants defining the substrate selectivity of each transporter. Recently, the improvement of computational power and experimental methods such as X-ray and cryo-EM crystallography permitted to conduct structure-based studies on specific transporters having important pharmacological impact. However, a lot remains to be discovered regarding their dynamics, transport modulation and ligand recognition. A detailed functional characterization of transporters would provide opportunities to develop new compounds targeting these key drug targets. Here, we are giving an overview of two major human LeuT-fold families, SLC6 and SLC7, with an emphasis on the most relevant members of each family for drug development. We gather the most recent understanding on the structural determinants of selectivity within and across the two families. We then use this information to discuss the benefits of a more generalized structural and functional annotation of the LeuT fold and the implications of such mapping for drug discovery.
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Affiliation(s)
- Claire Colas
- University of Vienna, Department of Pharmaceutical Chemistry, Vienna, Austria
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6
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Exploring the molecular determinants for subtype-selectivity of 2-amino-1,4,5,6-tetrahydropyrimidine-5-carboxylic acid analogs as betaine/GABA transporter 1 (BGT1) substrate-inhibitors. Sci Rep 2020; 10:12992. [PMID: 32747622 PMCID: PMC7400577 DOI: 10.1038/s41598-020-69908-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 07/17/2020] [Indexed: 12/13/2022] Open
Abstract
We have previously identified 2-amino-1,4,5,6-tetrahydropyrimidine-5-carboxylic acid (ATPCA) as the most potent substrate-inhibitor of the betaine/GABA transporter 1 (BGT1) (IC50 2.5 µM) reported to date. Herein, we characterize the binding mode of 20 novel analogs and propose the molecular determinants driving BGT1-selectivity. A series of N1-, exocyclic-N-, and C4-substituted analogs was synthesized and pharmacologically characterized in radioligand-based uptake assays at the four human GABA transporters (hGATs) recombinantly expressed in mammalian cells. Overall, the analogs retained subtype-selectivity for hBGT1, though with lower inhibitory activities (mid to high micromolar IC50 values) compared to ATPCA. Further characterization of five of these BGT1-active analogs in a fluorescence-based FMP assay revealed that the compounds are substrates for hBGT1, suggesting they interact with the orthosteric site of the transporter. In silico-guided mutagenesis experiments showed that the non-conserved residues Q299 and E52 in hBGT1 as well as the conformational flexibility of the compounds potentially contribute to the subtype-selectivity of ATPCA and its analogs. Overall, this study provides new insights into the molecular interactions governing the subtype-selectivity of BGT1 substrate-inhibitors. The findings may guide the rational design of BGT1-selective pharmacological tool compounds for future drug discovery.
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7
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El-Chami C, Foster AR, Johnson C, Clausen RP, Cornwell P, Haslam IS, Steward MC, Watson REB, Young HS, O'Neill CA. Organic osmolytes increase expression of specific tight junction proteins in skin and alter barrier function in keratinocytes. Br J Dermatol 2020; 184:482-494. [PMID: 32348549 DOI: 10.1111/bjd.19162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND The epidermal barrier is important for water conservation, failure of which is evident in dry-skin conditions. Barrier function is fulfilled by the stratum corneum, tight junctions (TJs, which control extracellular water) and keratinocyte mechanisms, such as organic osmolyte transport, which regulate intracellular water homeostasis. Organic osmolyte transport by keratinocytes is largely unexplored and nothing is known regarding how cellular and extracellular mechanisms of water conservation may interact. OBJECTIVES We aimed to characterize osmolyte transporters in skin and keratinocytes, and, using transporter inhibitors, to investigate whether osmolytes can modify TJs. Such modification would suggest a possible link between intracellular and extracellular mechanisms of water regulation in skin. METHODS Immunostaining and quantitative polymerase chain reaction of organic osmolyte-treated organ-cultured skin were used to identify changes to organic osmolyte transporters, and TJ protein and gene expression. TJ functional assays were performed on organic osmolyte-treated primary human keratinocytes in culture. RESULTS Immunostaining demonstrated the expression of transporters for betaine, taurine and myo-inositol in transporter-specific patterns. Treatment of human skin with either betaine or taurine increased the expression of claudin-1, claudin-4 and occludin. Osmolyte transporter inhibition abolished this response. Betaine and taurine increased TJ function in primary human keratinocytes in vitro. CONCLUSIONS Treatment of skin with organic osmolytes modulates TJ structure and function, which could contribute to the epidermal barrier. This emphasizes a role for organic osmolytes beyond the maintenance of intracellular osmolarity. This could be harnessed to enhance topical therapies for diseases characterized by skin barrier dysfunction.
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Affiliation(s)
- C El-Chami
- Centre for Dermatology Research, Division of Musculoskeletal and Dermatological Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - A R Foster
- Centre for Dermatology Research, Division of Musculoskeletal and Dermatological Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - C Johnson
- School of Electrical and Electronic Engineering, Faculty of Science and Engineering, University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - R P Clausen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - P Cornwell
- TRI Princeton, 601 Prospect Avenue, Princeton, NJ, 08540, USA
| | - I S Haslam
- Centre for Dermatology Research, Division of Musculoskeletal and Dermatological Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, UK.,Department of Biological Sciences, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UK
| | - M C Steward
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - R E B Watson
- Centre for Dermatology Research, Division of Musculoskeletal and Dermatological Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, UK.,NIHR Manchester Biomedical Research Centre, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - H S Young
- Centre for Dermatology Research, Division of Musculoskeletal and Dermatological Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, UK.,Department of Dermatology, Salford Royal NHS Foundation Trust, Manchester, UK
| | - C A O'Neill
- Centre for Dermatology Research, Division of Musculoskeletal and Dermatological Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester, M13 9PT, UK
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8
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Łątka K, Jończyk J, Bajda M. γ-Aminobutyric acid transporters as relevant biological target: Their function, structure, inhibitors and role in the therapy of different diseases. Int J Biol Macromol 2020; 158:S0141-8130(20)32987-1. [PMID: 32360967 DOI: 10.1016/j.ijbiomac.2020.04.126] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 04/17/2020] [Accepted: 04/18/2020] [Indexed: 12/13/2022]
Abstract
γ-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the nervous system. It plays a crucial role in many physiological processes. Upon release from the presynaptic element, it is removed from the synaptic cleft by reuptake due to the action of GABA transporters (GATs). GATs belong to a large SLC6 protein family whose characteristic feature is sodium-dependent relocation of neurotransmitters through the cell membrane. GABA transporters are characterized in many contexts, but their spatial structure is not fully known. They are divided into four types, which differ in occurrence and role. Herein, the special attention was paid to these transporting proteins. This comprehensive review presents the current knowledge about GABA transporters. Their distribution in the body, physiological functions and possible utilization in the therapy of different diseases were fully discussed. The important structural features were described based on published data, including sequence analysis, mutagenesis studies, and comparison with known SLC6 transporters for leucine (LeuT), dopamine (DAT) and serotonin (SERT). Moreover, the most important inhibitors of GABA transporters of various basic scaffolds, diverse selectivity and potency were presented.
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Affiliation(s)
- Kamil Łątka
- Jagiellonian University Medical College, Faculty of Pharmacy, Department of Physicochemical Drug Analysis, 30-688 Cracow, Medyczna 9, Poland
| | - Jakub Jończyk
- Jagiellonian University Medical College, Faculty of Pharmacy, Department of Physicochemical Drug Analysis, 30-688 Cracow, Medyczna 9, Poland
| | - Marek Bajda
- Jagiellonian University Medical College, Faculty of Pharmacy, Department of Physicochemical Drug Analysis, 30-688 Cracow, Medyczna 9, Poland.
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9
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Lie MEK, Kickinger S, Skovgaard-Petersen J, Ecker GF, Clausen RP, Schousboe A, White HS, Wellendorph P. Pharmacological Characterization of a Betaine/GABA Transporter 1 (BGT1) Inhibitor Displaying an Unusual Biphasic Inhibition Profile and Anti-seizure Effects. Neurochem Res 2020; 45:1551-1565. [PMID: 32248400 PMCID: PMC7297817 DOI: 10.1007/s11064-020-03017-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/09/2020] [Accepted: 03/18/2020] [Indexed: 12/01/2022]
Abstract
Focal epileptic seizures can in some patients be managed by inhibiting γ-aminobutyric acid (GABA) uptake via the GABA transporter 1 (GAT1) using tiagabine (Gabitril®). Synergistic anti-seizure effects achieved by inhibition of both GAT1 and the betaine/GABA transporter (BGT1) by tiagabine and EF1502, compared to tiagabine alone, suggest BGT1 as a target in epilepsy. Yet, selective BGT1 inhibitors are needed for validation of this hypothesis. In that search, a series of BGT1 inhibitors typified by (1R,2S)-2-((4,4-bis(3-methylthiophen-2-yl)but-3-en-yl)(methyl)amino)cyclohexanecarboxylic acid (SBV2-114) was developed. A thorough pharmacological characterization of SBV2-114 using a cell-based [3H]GABA uptake assay at heterologously expressed BGT1, revealed an elusive biphasic inhibition profile with two IC50 values (4.7 and 556 μM). The biphasic profile was common for this structural class of compounds, including EF1502, and was confirmed in the MDCK II cell line endogenously expressing BGT1. The possibility of two binding sites for SBV2-114 at BGT1 was assessed by computational docking studies and examined by mutational studies. These investigations confirmed that the conserved residue Q299 in BGT1 is involved in, but not solely responsible for the biphasic inhibition profile of SBV2-114. Animal studies revealed anti-seizure effects of SBV2-114 in two mouse models, supporting a function of BGT1 in epilepsy. However, as SBV2-114 is apparent to be rather non-selective for BGT1, the translational relevance of this observation is unknown. Nevertheless, SBV2-114 constitutes a valuable tool compound to study the molecular mechanism of an emerging biphasic profile of BGT1-mediated GABA transport and the putative involvement of two binding sites for this class of compounds.
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Affiliation(s)
- Maria E K Lie
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| | - Stefanie Kickinger
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | | | - Gerhard F Ecker
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Rasmus P Clausen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - H Steve White
- Department of Pharmacy, University of Washington, Washington, USA
| | - Petrine Wellendorph
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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10
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Yadav A, Shah N, Tiwari PK, Javed K, Cheng Q, Aidhen IS, Bröer S. Novel Chemical Scaffolds to Inhibit the Neutral Amino Acid Transporter B 0AT1 (SLC6A19), a Potential Target to Treat Metabolic Diseases. Front Pharmacol 2020; 11:140. [PMID: 32180718 PMCID: PMC7059793 DOI: 10.3389/fphar.2020.00140] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/03/2020] [Indexed: 11/13/2022] Open
Abstract
Lack of B0AT1 (SLC6A19) partially protects mice against the onset of non-alcoholic steatohepatitis (NASH). To achieve a similar outcome through pharmacological treatment, we improved previously identified inhibitors of B0AT1 by medicinal chemistry and identified second generation inhibitors by high through-put screening. Modified diarylmethine compounds inhibited B0AT1 with IC50 values ranging from 8-90 μM. A second generation of inhibitors was derived from high-throughput screening and showed higher affinity (IC50 of 1-15 μM) and strong selectivity against amino acid transporters with similar substrate specificity, such as ASCT2 (SLC1A5) and LAT1 (SLC7A5). All compounds were unrelated to B0AT1 substrates, but were likely to bind in the vicinity of the substrate binding site.
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Affiliation(s)
- Aditya Yadav
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Nishank Shah
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | | | - Kiran Javed
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Qi Cheng
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | | | - Stefan Bröer
- Research School of Biology, Australian National University, Canberra, ACT, Australia
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11
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Abstract
Amino acids perform a variety of functions in cells and organisms, particularly in the synthesis of proteins, as energy metabolites, neurotransmitters, and precursors for many other molecules. Amino acid transport plays a key role in all these functions. Inhibition of amino acid transport is pursued as a therapeutic strategy in several areas, such as diabetes and related metabolic disorders, neurological disorders, cancer, and stem cell biology. The role of amino acid transporters in these disorders and processes is well established, but the implementation of amino acid transporters as drug targets is still in its infancy. This is at least in part due to the underdeveloped pharmacology of this group of membrane proteins. Recent advances in structural biology, membrane protein expression, and inhibitor screening methodology will see an increased number of improved and selective inhibitors of amino acid transporters that can serve as tool compounds for further studies.
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Affiliation(s)
- Stefan Bröer
- 1 Research School of Biology, College of Science, The Australian National University, Canberra, ACT, Australia
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Giraudo A, Krall J, Bavo F, Nielsen B, Kongstad KT, Rolando B, De Blasio R, Gloriam DE, Löffler R, Thiesen L, Harpsøe K, Frydenvang K, Boschi D, Wellendorph P, Lolli ML, Jensen AA, Frølund B. Five-Membered N-Heterocyclic Scaffolds as Novel Amino Bioisosteres at γ-Aminobutyric Acid (GABA) Type A Receptors and GABA Transporters. J Med Chem 2019; 62:5797-5809. [DOI: 10.1021/acs.jmedchem.9b00026] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Alessandro Giraudo
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
- Department of Science and Drug Technology, University of Torino,
Via Pietro Giuria 9, 10125 Torino, Italy
| | - Jacob Krall
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Francesco Bavo
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
- Department of Pharmaceutical Sciences, University of Milan, via Mangiagalli 25, 20133 Milano, Italy
| | - Birgitte Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Kenneth T. Kongstad
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Barbara Rolando
- Department of Science and Drug Technology, University of Torino,
Via Pietro Giuria 9, 10125 Torino, Italy
| | - Rossella De Blasio
- Department of Science and Drug Technology, University of Torino,
Via Pietro Giuria 9, 10125 Torino, Italy
| | - David E. Gloriam
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Rebekka Löffler
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Louise Thiesen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Kasper Harpsøe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Karla Frydenvang
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Donatella Boschi
- Department of Science and Drug Technology, University of Torino,
Via Pietro Giuria 9, 10125 Torino, Italy
| | - Petrine Wellendorph
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Marco L. Lolli
- Department of Science and Drug Technology, University of Torino,
Via Pietro Giuria 9, 10125 Torino, Italy
| | - Anders A. Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Bente Frølund
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
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13
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Kickinger S, Hellsberg E, Frølund B, Schousboe A, Ecker GF, Wellendorph P. Structural and molecular aspects of betaine-GABA transporter 1 (BGT1) and its relation to brain function. Neuropharmacology 2019; 161:107644. [PMID: 31108110 DOI: 10.1016/j.neuropharm.2019.05.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 04/14/2019] [Accepted: 05/16/2019] [Indexed: 01/09/2023]
Abstract
ɣ-aminobutyric-acid (GABA) functions as the principal inhibitory neurotransmitter in the central nervous system. Imbalances in GABAergic neurotransmission are involved in the pathophysiology of various neurological diseases such as epilepsy, Alzheimer's disease and stroke. GABA transporters (GATs) facilitate the termination of GABAergic signaling by transporting GABA together with sodium and chloride from the synaptic cleft into presynaptic neurons and surrounding glial cells. Four different GATs have been identified that all belong to the solute carrier 6 (SLC6) transporter family: GAT1-3 (SLC6A1, SLC6A13, SLC6A11) and betaine/GABA transporter 1 (BGT1, SLC6A12). BGT1 has emerged as an interesting target for treating epilepsy due to animal studies that reported anticonvulsant effects for the GAT1/BGT1 selective inhibitor EF1502 and the BGT1 selective inhibitor RPC-425. However, the precise involvement of BGT1 in epilepsy remains elusive because of its controversial expression levels in the brain and the lack of highly selective and potent tool compounds. This review gathers the current structural and functional knowledge on BGT1 with emphasis on brain relevance, discusses all available compounds, and tries to shed light on the molecular determinants driving BGT1 selectivity. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- Stefanie Kickinger
- University of Vienna, Department of Pharmaceutical Chemistry, Althanstrasse 14, 1090, Vienna, Austria
| | - Eva Hellsberg
- University of Vienna, Department of Pharmaceutical Chemistry, Althanstrasse 14, 1090, Vienna, Austria
| | - Bente Frølund
- University of Copenhagen, Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, 2 Universitetsparken, 2100, Copenhagen, Denmark
| | - Arne Schousboe
- University of Copenhagen, Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, 2 Universitetsparken, 2100, Copenhagen, Denmark
| | - Gerhard F Ecker
- University of Vienna, Department of Pharmaceutical Chemistry, Althanstrasse 14, 1090, Vienna, Austria
| | - Petrine Wellendorph
- University of Copenhagen, Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, 2 Universitetsparken, 2100, Copenhagen, Denmark.
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14
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Lie ME, Gowing EK, Johansen NB, Dalby NO, Thiesen L, Wellendorph P, Clarkson AN. GAT3 selective substrate l-isoserine upregulates GAT3 expression and increases functional recovery after a focal ischemic stroke in mice. J Cereb Blood Flow Metab 2019; 39:74-88. [PMID: 29160736 PMCID: PMC6311676 DOI: 10.1177/0271678x17744123] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ischemic stroke triggers an elevation in tonic GABA inhibition that impairs the ability of the brain to form new structural and functional cortical circuits required for recovery. This stroke-induced increase in tonic inhibition is caused by impaired GABA uptake via the glial GABA transporter GAT3, highlighting GAT3 as a novel target in stroke recovery. Using a photothrombotic stroke mouse model, we show that GAT3 protein levels are decreased in peri-infarct tissue from 6 h to 42 days post-stroke. Prior studies have shown that GAT substrates can increase GAT surface expression. Therefore, we aimed to assess whether the GAT3 substrate, L-isoserine, could increase post-stroke functional recovery. L-Isoserine (38 µM or 380 µM) administered directly into the infarct from day 5 to 32 post-stroke, significantly increased motor performance in the grid-walking and cylinder tasks in a concentration-dependent manner, without affecting infarct volumes. Additionally, L-isoserine induced a lasting increase in GAT3 expression in peri-infarct regions accompanied by a small decrease in GFAP expression. This study is the first to show that a GAT3 substrate can increase GAT3 expression and functional recovery after focal ischemic stroke following a delayed long-term treatment. We propose that enhancing GAT3-mediated uptake dampens tonic inhibition and promotes functional recovery after stroke.
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Affiliation(s)
- Maria Ek Lie
- 1 Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.,2 Department of Anatomy, Brain Health Research Centre and Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Emma K Gowing
- 2 Department of Anatomy, Brain Health Research Centre and Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Nina B Johansen
- 1 Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Nils Ole Dalby
- 1 Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Louise Thiesen
- 1 Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Petrine Wellendorph
- 1 Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Andrew N Clarkson
- 2 Department of Anatomy, Brain Health Research Centre and Brain Research New Zealand, University of Otago, Dunedin, New Zealand.,3 Faculty of Pharmacy, The University of Sydney, Sydney, New South Wales, Australia
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15
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Suemasa A, Watanabe M, Kobayashi T, Suzuki H, Fukuda H, Minami M, Shuto S. Design and synthesis of cyclopropane-based conformationally restricted GABA analogues as selective inhibitors for betaine/GABA transporter 1. Bioorg Med Chem Lett 2018; 28:3395-3399. [DOI: 10.1016/j.bmcl.2018.08.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 08/25/2018] [Accepted: 08/25/2018] [Indexed: 12/26/2022]
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16
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Al-Khawaja A, Haugaard AS, Marek A, Löffler R, Thiesen L, Santiveri M, Damgaard M, Bundgaard C, Frølund B, Wellendorph P. Pharmacological Characterization of [ 3H]ATPCA as a Substrate for Studying the Functional Role of the Betaine/GABA Transporter 1 and the Creatine Transporter. ACS Chem Neurosci 2018; 9:545-554. [PMID: 29131576 DOI: 10.1021/acschemneuro.7b00351] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The betaine/γ-aminobutyric acid (GABA) transporter 1 (BGT1) is one of the four GABA transporters (GATs) involved in the termination of GABAergic neurotransmission. Although suggested to be implicated in seizure management, the exact functional importance of BGT1 in the brain is still elusive. This is partly owing to the lack of potent and selective pharmacological tool compounds that can be used to probe its function. We previously reported the identification of 2-amino-1,4,5,6-tetrahydropyrimidine-5-carboxylic acid (ATPCA), a selective substrate for BGT1 over GAT1/GAT3, but also an agonist for GABAA receptors. With the aim of providing new functional insight into BGT1, we here present the synthesis and pharmacological characterization of the tritiated analogue, [3H]ATPCA. Using traditional uptake assays at recombinant transporters expressed in cell lines, [3H]ATPCA displayed a striking selectivity for BGT1 among the four GATs ( Km and Vmax values of 21 μM and 3.6 nmol ATPCA/(min × mg protein), respectively), but was also found to be a substrate for the creatine transporter (CreaT). In experiments with mouse cortical cell cultures, we observed a Na+-dependent [3H]ATPCA uptake in neurons, but not in astrocytes. The neuronal uptake could be inhibited by GABA, ATPCA, and a noncompetitive BGT1-selective inhibitor, indicating functional BGT1 in neurons. In conclusion, we report [3H]ATPCA as a novel radioactive substrate for both BGT1 and CreaT. The dual activity of the radioligand makes it most suitable for use in recombinant studies.
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Affiliation(s)
- Anas Al-Khawaja
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Anne S. Haugaard
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Ales Marek
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam 542/2, 16610 Prague 6, Czech Republic
| | - Rebekka Löffler
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Louise Thiesen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Mònica Santiveri
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Maria Damgaard
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | | | - Bente Frølund
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Petrine Wellendorph
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
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