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Li M, Zhang X, Chen S, Liu H, Zhang YW. Unique Substrate Recognition and Sodium-Substrate Binding Stoichiometry in a Bacterial Serotonin Transporter, TuriSERT. Int J Mol Sci 2023; 24:17112. [PMID: 38069433 PMCID: PMC10707687 DOI: 10.3390/ijms242317112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/27/2023] [Accepted: 12/02/2023] [Indexed: 12/18/2023] Open
Abstract
All resolved high-resolution structures of the transporters in the neurotransmitter sodium symporter (NSS) family revealed that the NSS members share common structural and mechanistic features for substrate and ion binding and transport. However, a recently reported bacterial orthologue of the human serotonin transporter (hSERT), TuriSERT, possesses a structural characteristic specific for amino acid substrate binding but does transport a biogenic amine. The unique structural feature of TuriSERT requires a novel configuration for coordinating its substrate and ions. In the present study, we characterized TuriSERT expressed in Escherichia coli cells with a fluorescent substrate by biochemical, structural, and pharmacological approaches. Substrate transport by TuriSERT requires Na+ but not Cl-. Replacement of Asp262 by asparagine renders TuriSERT Cl--dependent. Substitutions of the corresponding Na1 residues did not alter Na+ dependence on substrate transport, whereas the mutation of a Na2 site residue led to a loss of transport activity, suggesting that Na+ binds only to the Na2 site in TuriSERT. In addition, substitutions of several residues essential for recognizing 5-hydroxytryptamine (5-HT) in hSERT had little effect on 5-HT displacement potency in transport assay for TuriSERT. In contrast, mutations of the residues that are proposed to coordinate with 5-HT in our docking model dramatically reduced 5-HT displacement. Furthermore, our results indicated that all tested antidepressants showed a weak inhibitory effect on TuriSERT. The present study demonstrated the existence of a unique substrate binding site and 1:1 stoichiometry of sodium-substrate binding in TuriSERT, a novel structural finding for the NSS transporters.
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Affiliation(s)
| | | | | | | | - Yuan-Wei Zhang
- School of Life Sciences, Guangzhou University, Guangzhou 510006, China; (M.L.); (X.Z.); (S.C.); (H.L.)
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2
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Camacho-Hernandez GA, Jahan K, Newman AH. Illuminating the monoamine transporters: Fluorescently labelled ligands to study dopamine, serotonin and norepinephrine transporters. Basic Clin Pharmacol Toxicol 2023; 133:473-484. [PMID: 36527444 PMCID: PMC11309735 DOI: 10.1111/bcpt.13827] [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: 10/11/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022]
Abstract
Fluorescence microscopy has revolutionized the visualization of physiological processes in live-cell systems. With the recent innovations in super resolution microscopy, these events can be examined with high precision and accuracy. The development of fluorescently labelled small molecules has provided a significant advance in understanding the physiological relevance of targeted proteins that can now be visualized at the cellular level. One set of physiologically important target proteins are the monoamine transporters (MATs) that play an instrumental role in maintaining monoamine signalling homeostasis. Understanding the mechanisms underlying their regulation and dysregulation is fundamental to treating several neuropsychiatric conditions such as attention deficit hyperactivity disorder (ADHD), anxiety, depression and substance use disorders. Herein, we describe the rationale behind the small molecule design of fluorescently labelled ligands (FLL) either as MAT substrates or inhibitors as well as their applications to advance our understanding of this class of transporters in health and disease.
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Affiliation(s)
- Gisela Andrea Camacho-Hernandez
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes on Drug Abuse - Intramural Research Program, Baltimore, Maryland, USA
| | - Khorshada Jahan
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes on Drug Abuse - Intramural Research Program, Baltimore, Maryland, USA
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes on Drug Abuse - Intramural Research Program, Baltimore, Maryland, USA
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3
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Nguyen VT, Harris AC, Eltit JM. Structural and functional perspectives on interactions between synthetic cathinones and monoamine transporters. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2023; 99:83-124. [PMID: 38467490 DOI: 10.1016/bs.apha.2023.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
Synthetic cathinone derivatives comprise a family of psychoactive compounds structurally related to amphetamine. Over the last decade, clandestine chemists have synthesized a consistent stream of innovative cathinone derivatives to outpace governmental regulatory restrictions. Many of these unregulated substances are produced and distributed as designer drugs. Two of the principal chemical scaffolds exploited to expand the synthetic cathinone family are methcathinone and α-pyrrolidinopentiophenone (or α-pyrrolidinovalerophenone, α-PVP). These compounds' main physiological targets are monoamine transporters, where they promote addiction by potentiating dopaminergic neurotransmission. This chapter describes techniques used to study the pharmacodynamic properties of cathinones at monoamine transporters in vitro. Biochemical techniques described include uptake inhibition and release assays in rat brain synaptosomes and in mammalian expression systems. Electrophysiological techniques include current measurements using the voltage clamp technique. We describe a Ca2+ mobilization assay wherein voltage-gated Ca2+ channels function as reporters to study the action of synthetic cathinones at monoamine transporters. We discuss results from systematic structure-activity relationship studies on simple and complex cathinones at monoamine transporters with an emphasis on identifying structural moieties that modulate potency and selectivity at these transporters. Moreover, different profiles of selectivity at monoamine transporters directly predict compounds associated with behavioral and subjective effects within animals and humans. In conclusion, clarification of the structural aspects of compounds which modulate potency and selectivity at monoamine transporters is critical to identify and predict potential addictive drugs. This knowledge may allow prompt allocation of resources toward drugs that represent the greatest threats after drugs are identified by forensic laboratories.
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Affiliation(s)
- Vy T Nguyen
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - Alan C Harris
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - Jose M Eltit
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States.
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4
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Davies RA, Nguyen VT, Eltit JM, Glennon RA. Structure-Activity Relationships for a Recently Controlled Synthetic Cathinone Dopamine Transporter Reuptake Inhibitor: α-Pyrrolidinohexiophenone (α-PHP). ACS Chem Neurosci 2023; 14:2527-2536. [PMID: 37406364 PMCID: PMC10670441 DOI: 10.1021/acschemneuro.3c00156] [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] [Indexed: 07/07/2023] Open
Abstract
α-Pyrrolidinohexiophenone (α-PHP) is the one-carbon unit α-extended homolog of the better-known and widely abused synthetic cathinone central stimulant α-PVP ("flakka"); both are now U.S. Schedule I controlled substances. Structurally, α-PVP and α-PHP possess a common terminal N-pyrrolidine moiety and differ only with respect to the length of their α-alkyl chain. Using a synaptosomal assay, we previously reported that α-PHP is at least as potent as α-PVP as a dopamine transporter (DAT) reuptake inhibitor. A systematic structure-activity study of synthetic cathinones (e.g., α-PHP) as DAT reuptake inhibitors (i.e., transport blockers), a mechanism thought responsible for their abuse liability, has yet to be conducted. Here, we examined a series of 4-substituted α-PHP analogues and found that, with one exception, all behaved as relatively (28- to >300-fold) selective DAT versus serotonin transporter (SERT) reuptake inhibitors with DAT inhibition potencies of most falling within a very narrow (i.e., <3-fold) range. The 4-CF3 analogue of α-PHP was a confirmed "outlier" in that it was at least 80-fold less potent than the other analogues and displayed reduced (i.e., no) DAT vs SERT selectivity. Consideration of various physicochemical properties of the CF3 group, relative to that of the other substituents involved here, provided relatively little insight. Unlike with DAT-releasing agents, as previously reported by us, a QSAR study was precluded because of the limited range of empirical results (with the exception of the 4-CF3 analogue) for DAT reuptake inhibition.
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Affiliation(s)
- Rachel A. Davies
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University; Richmond, Virginia 23298 U.S
| | - Vy T. Nguyen
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University; Richmond, Virginia 23298 U.S
| | - Jose M. Eltit
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University; Richmond, Virginia 23298 U.S
| | - Richard A. Glennon
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University; Richmond, Virginia 23298 U.S
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5
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Clauss NJ, Mayer FP, Owens WA, Vitela M, Clarke KM, Bowman MA, Horton RE, Gründemann D, Schmid D, Holy M, Gould GG, Koek W, Sitte HH, Daws LC. Ethanol inhibits dopamine uptake via organic cation transporter 3: Implications for ethanol and cocaine co-abuse. Mol Psychiatry 2023; 28:2934-2945. [PMID: 37308680 PMCID: PMC10615754 DOI: 10.1038/s41380-023-02064-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 12/20/2022] [Accepted: 03/29/2023] [Indexed: 06/14/2023]
Abstract
Concurrent cocaine and alcohol use is among the most frequent drug combination, and among the most dangerous in terms of deleterious outcomes. Cocaine increases extracellular monoamines by blocking dopamine (DA), norepinephrine (NE) and serotonin (5-HT) transporters (DAT, NET and SERT, respectively). Likewise, ethanol also increases extracellular monoamines, however evidence suggests that ethanol does so independently of DAT, NET and SERT. Organic cation transporter 3 (OCT3) is an emergent key player in the regulation of monoamine signaling. Using a battery of in vitro, in vivo electrochemical, and behavioral approaches, as well as wild-type and constitutive OCT3 knockout mice, we show that ethanol's actions to inhibit monoamine uptake are dependent on OCT3. These findings provide a novel mechanistic basis whereby ethanol enhances the neurochemical and behavioral effects of cocaine and encourage further research into OCT3 as a target for therapeutic intervention in the treatment of ethanol and ethanol/cocaine use disorders.
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Affiliation(s)
- N J Clauss
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - F P Mayer
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090, Vienna, Austria
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, DK-2200, Denmark
| | - W A Owens
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - M Vitela
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - K M Clarke
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - M A Bowman
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - R E Horton
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - D Gründemann
- Department of Pharmacology, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50931, Cologne, Germany
| | - D Schmid
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090, Vienna, Austria
| | - M Holy
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090, Vienna, Austria
| | - G G Gould
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - W Koek
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - H H Sitte
- Center for Physiology and Pharmacology, Medical University of Vienna, 1090, Vienna, Austria
- Center for Addiction Research and Science, Medical University Vienna, Waehringerstrasse 13 A, 1090, Vienna, Austria
| | - L C Daws
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA.
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA.
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6
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Jones CB, Eltit JM, Dukat M. Do 2-(Benzoyl)piperidines Represent a Novel Class of hDAT Reuptake Inhibitors? ACS Chem Neurosci 2023; 14:741-748. [PMID: 36745029 DOI: 10.1021/acschemneuro.2c00666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
2-(Benzoyl)piperidines (analogues of 1a), structural hybrids of the clinically employed ADHD medication methylphenidate (2) and the abused synthetic cathinone pentedrone (3), have been previously reported to act as novel and selective reuptake inhibitors of the human dopamine transporter (hDAT). One of the more potent benzoylpiperidines, as is the case with methylphenidate analogues, is its 3,4-dichloroaryl counterpart. Here, we demonstrate using homology models that these compounds (i.e., benzoylpiperidines and methylphenidate analogues) likely bind in a comparable manner at hDAT. In addition, it is shown here that the 3,4-dichlorobenzoylpiperidine analogue of 1a is more potent than its 3,4-dimethyl counterpart, suggesting that the electronic character of the substituents might play a role in the potency of these hybrids. Furthermore, the 3,4-benz-fused (i.e., naphthyl) benzoylpiperidine analogue acts in the same manner as its corresponding methylphenidate counterpart at hDAT. As with its methylphenidate counterpart, the naphthyl compound also acts, rather uniquely (although with lower potency) relative to other members of the two series, at the human serotonin transporter (hSERT). In conclusion, the benzoylpiperidines represent a novel structural class of hDAT reuptake inhibitors that function in a manner similar to their methylphenidate counterparts.
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Affiliation(s)
- Charles B Jones
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, P.O. Box 980540, Richmond, Virginia 23298, United States
| | - Jose M Eltit
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, P.O. Box 980551, Richmond, Virginia 23298, United States
| | - Małgorzata Dukat
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, P.O. Box 980540, Richmond, Virginia 23298, United States
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7
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Lim J, Bang Y, Kim KM, Choi HJ. Differentiated HT22 cells as a novel model for in vitro screening of serotonin reuptake inhibitors. Front Pharmacol 2023; 13:1062650. [PMID: 36703746 PMCID: PMC9871236 DOI: 10.3389/fphar.2022.1062650] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/13/2022] [Indexed: 01/12/2023] Open
Abstract
The mouse hippocampal neuronal cell line HT22 is frequently used as an in vitro model to investigate the role of hippocampal cholinergic neurons in cognitive functions. HT22 cells are derived from hippocampal neuronal HT4 cells. However, whether these cells exhibit the serotonergic neuronal phenotype observed in mature hippocampal neurons has not been determined yet. In this present study, we examined whether the differentiation of HT22 cells enhances the serotonergic neuronal phenotype, and if so, whether it can be used for antidepressant screening. Our results show that differentiation of HT22 cells promoted neurite outgrowth and upregulation of N-methyl-D-aspartate receptor and choline acetyltransferase, which is similar to that observed in primary cultured hippocampal neurons. Furthermore, proteins required for serotonergic neurotransmission, such as tryptophan hydroxylase 2, serotonin (5-hydroxytryptamine, 5-HT)1a receptor, and serotonin transporter (SERT), were significantly upregulated in differentiated HT22 cells. The transcription factor Pet-1 was upregulated during HT22 differentiation and was responsible for the regulation of the serotonergic neuronal phenotype. Differentiation also enhanced the functional serotonergic properties of HT22 cells, as evidenced by increase in intracellular 5-HT levels, serotonin transporter SERT glycosylation, and 5-HT reuptake activity. The sensitivity of 5-HT reuptake inhibition by venlafaxine in differentiated HT22 cells (IC50, 27.21 nM) was comparable to that in HEK293 cells overexpressing serotonin transporter SERT (IC50, 30.65 nM). These findings suggest that the differentiation of HT22 cells enhances their functional serotonergic properties, and these cells could be a potential in vitro system for assessing the efficacy of antidepressant 5-HT reuptake inhibitors.
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Affiliation(s)
- Juhee Lim
- College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, Pocheon, Gyeonggi-do, South Korea,College of Pharmacy and Research Institute of Pharmaceutical Sciences, Woosuk University, Wanju, Jeollabuk-do, South Korea
| | - Yeojin Bang
- College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, Pocheon, Gyeonggi-do, South Korea
| | - Kyeong-Man Kim
- College of Pharmacy, Chonnam National University, Gwangju, South Korea
| | - Hyun Jin Choi
- College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, Pocheon, Gyeonggi-do, South Korea,*Correspondence: Hyun Jin Choi,
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8
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Liu H, Wu Y, Li C, Tang Q, Zhang YW. Molecular docking and biochemical validation of (-)-syringaresinol-4-O-β-D-apiofuranosyl-(1→2)-β-D-glucopyranoside binding to an allosteric site in monoamine transporters. Front Pharmacol 2022; 13:1018473. [PMID: 36386236 PMCID: PMC9649612 DOI: 10.3389/fphar.2022.1018473] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 10/17/2022] [Indexed: 06/11/2024] Open
Abstract
Albizia julibrissin Durazz is one of the most common herbs used for depression and anxiety treatment, but its mechanism of action as an antidepressant or anxiolytic drug have not been fully understood. We previously isolated and identified one lignan glycoside compound from Albizia Julibrissin Durazz, (-)-syringaresinol-4-O-β-D-apiofuranosyl-(1→2)-β-D-glucopyranoside (SAG), that inhibited all three monoamine transporters with a mechanism of action different from that of the conventional antidepressants. In this study, we generated homology models for human dopamine transporter and human norepinephrine transporter, based on the X-ray structure of Drosophila dopamine transporter, and conducted the molecular docking of SAG to all three human monoamine transporters. Our computational results indicated that SAG binds to an allosteric site (S2) that has been demonstrated to be formed by an aromatic pocket positioned in the scaffold domain in the extracellular vestibule connected to the central site (S1) in these monoamine transporters. In addition, we demonstrated that SAG stabilizes a conformation of serotonin transporter with both the extracellular and cytoplasmic pathways closed. Furthermore, we performed mutagenesis of the residues in both the allosteric and orthosteric sites to biochemically validate SAG binding in all three monoamine transporters. Our results are consistent with the molecular docking calculation and support the association of SAG with the allosteric site. We expect that this herbal molecule could become a lead compound for the development of new therapeutic agents with a novel mechanism of action.
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Affiliation(s)
- Hanhe Liu
- School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Yingyao Wu
- School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Chan Li
- School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Qingfa Tang
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Chinese Medicine Pharmaceutics, Guangzhou, China
| | - Yuan-Wei Zhang
- School of Life Sciences, Guangzhou University, Guangzhou, China
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9
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Determining Ligand and Ion-Induced Conformational Changes in Serotonin Transporter with Its Fluorescent Substrates. Int J Mol Sci 2022; 23:ijms231810919. [PMID: 36142837 PMCID: PMC9503009 DOI: 10.3390/ijms231810919] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/14/2022] [Accepted: 09/16/2022] [Indexed: 01/22/2023] Open
Abstract
Conformational changes are fundamental events in the transport mechanism. The serotonin transporter (SERT) catalyzes reuptake of the neurotransmitter serotonin after its release by serotonergic neurons and is the molecular target for antidepressant drugs and psychostimulants. Despite significant progress in characterizing the structure-function relationship of SERT, its conformational mechanism has not been fully understood. We present here a cell-based method for determining conformational changes in SERT with its fluorescent substrates by fluorescence imaging analysis. This method fluorometrically measures accessibility of strategically positioned cysteine residues in the substrate permeation pathway to calculate the rate constants of reactivity with MTS reagents in live or permeabilized cells. We validated this method by investigating ligand and ion-induced conformational changes in both the extracellular and cytoplasmic pathways of SERT. Furthermore, we applied this method for examining the influence of Cl- binding and vilazodone inhibition on SERT conformation. Our results showed that Cl- ion, in the presence of Na+, facilitates the conformational conversion from outward to inward open states, and that vilazodone binding stabilizes SERT in an outward open and inward-closed conformation. The present work provided insights into the conformational mechanism of SERT and also indicated that the cell-based fluorometric method is robust, straightforward to perform, and potentially applicable to any monoamine transporters in exploring the transport mechanism and mechanism of action of therapeutic agents for the treatment of several psychiatric disorders.
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10
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Huang B, Liu H, Wu Y, Li C, Tang Q, Zhang YW. Two Lignan Glycosides from Albizia julibrissin Durazz. Noncompetitively Inhibit Serotonin Transporter. Pharmaceuticals (Basel) 2022; 15:ph15030344. [PMID: 35337141 PMCID: PMC8954383 DOI: 10.3390/ph15030344] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/07/2022] [Accepted: 03/10/2022] [Indexed: 12/11/2022] Open
Abstract
Albizia julibrissin Durazz. is one of the most common herbs used for depression and anxiety treatment, but its molecular basis and mechanism of action as an antidepressant or anxiolytic drug are not understood. In this study, we separated and identified two lignan glycosides that inhibit serotonin transporter (SERT) noncompetitively by decreasing Vmax with little change in Km for its fluorescence substrate. In addition, treatment with lignan glycosides did not alter total and cell surface expression levels of the transporter protein. The two compounds decreased the accessibility of a cysteine residue placed in the extracellular substrate permeation pathway by inducing a conformational shift toward an outward-closed state of SERT. These results are consistent with molecular docking for the association of the lignan glycosides to the allosteric site in SERT. The present work supports the proposal that these compounds act on SERT by a novel underlying mechanism of action different from that of conventional antidepressant drugs.
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Affiliation(s)
- Bishan Huang
- School of Life Sciences, Guangzhou University, Guangzhou 510006, China; (B.H.); (H.L.); (Y.W.); (C.L.)
| | - Hanhe Liu
- School of Life Sciences, Guangzhou University, Guangzhou 510006, China; (B.H.); (H.L.); (Y.W.); (C.L.)
| | - Yingyao Wu
- School of Life Sciences, Guangzhou University, Guangzhou 510006, China; (B.H.); (H.L.); (Y.W.); (C.L.)
| | - Chan Li
- School of Life Sciences, Guangzhou University, Guangzhou 510006, China; (B.H.); (H.L.); (Y.W.); (C.L.)
| | - Qingfa Tang
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou 510515, China;
- Guangdong Provincial Key Laboratory of Chinese Medicine Pharmaceutics, Guangzhou 510515, China
| | - Yuan-Wei Zhang
- School of Life Sciences, Guangzhou University, Guangzhou 510006, China; (B.H.); (H.L.); (Y.W.); (C.L.)
- Correspondence:
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11
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Tomlinson ID, Kovtun O, Torres R, Bellocchio LG, Josephs T, Rosenthal SJ. A Novel Biotinylated Homotryptamine Derivative for Quantum Dot Imaging of Serotonin Transporter in Live Cells. Front Cell Neurosci 2021; 15:667044. [PMID: 34867196 PMCID: PMC8637195 DOI: 10.3389/fncel.2021.667044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 10/19/2021] [Indexed: 11/21/2022] Open
Abstract
The serotonin transporter (SERT) is the primary target for selective serotonin reuptake inhibitor (SSRI) antidepressants that are thought to exert their therapeutic effects by increasing the synaptic concentration of serotonin. Consequently, probes that can be utilized to study cellular trafficking of SERT are valuable research tools. We have developed a novel ligand (IDT785) that is composed of a SERT antagonist (a tetrahydro pyridyl indole derivative) conjugated to a biotinylated poly ethylene glycol (PEG) via a phenethyl linker. This compound was determined to be biologically active and inhibited SERT-mediated reuptake of IDT307 with the half-maximal inhibitory concentration of 7.2 ± 0.3 μM. We demonstrated that IDT785 enabled quantum dot (QD) labeling of membrane SERT in transfected HEK-293 cultures that could be blocked using the high affinity serotonin reuptake inhibitor paroxetine. Molecular docking studies suggested that IDT785 might be binding to the extracellular vestibule binding site rather than the orthosteric substrate binding site, which could be attributable to the hydrophilicity of the PEG chain and the increased loss of degrees of freedom that would be required to penetrate into the orthosteric binding site. Using IDT785, we were able to study the membrane localization and membrane dynamics of YFP-SERT heterologously expressed in HEK-293 cells and demonstrated that SERT expression was enriched in the membrane edge and in thin cellular protrusions.
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Affiliation(s)
- Ian D. Tomlinson
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Oleg Kovtun
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Ruben Torres
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States
| | | | - Travis Josephs
- Neuroscience Program, Vanderbilt University, Nashville, TN, United States
| | - Sandra J. Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, TN, United States
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12
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Engevik M, Ruan W, Visuthranukul C, Shi Z, Engevik KA, Engevik AC, Fultz R, Schady DA, Spinler JK, Versalovic J. Limosilactobacillus reuteri ATCC 6475 metabolites upregulate the serotonin transporter in the intestinal epithelium. Benef Microbes 2021; 12:583-599. [PMID: 34550056 DOI: 10.3920/bm2020.0216] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The serotonin transporter (SERT) readily takes up serotonin (5-HT), thereby regulating the availability of 5-HT within the intestine. In the absence of SERT, 5-HT remains in the interstitial space and has the potential to aberrantly activate the many 5-HT receptors distributed on the epithelium, immune cells and enteric neurons. Perturbation of SERT is common in many gastrointestinal disorders as well as mouse models of colitis. Select commensal microbes regulate intestinal SERT levels, but the mechanism of this regulation is poorly understood. Additionally, ethanol upregulates SERT in the brain and dendritic cells, but its effects in the intestine have never been examined. We report that the intestinal commensal microbe Limosilactobacillus (previously classified as Lactobacillus) reuteri ATCC PTA 6475 secretes 83.4 mM ethanol. Consistent with the activity of L. reuteri alcohol dehydrogenases, we found that L. reuteri tolerated various levels of ethanol. Application of L. reuteri conditioned media or exogenous ethanol to human colonic T84 cells was found to upregulate SERT at the level of mRNA. A 4-(4-(dimethylamino) phenyl)-1-methylpyridinium (APP+) uptake assay confirmed the functional activity of SERT. These findings were mirrored in mouse colonic organoids, where L. reuteri metabolites and ethanol were found to upregulate SERT at the apical membrane. Finally, in a trinitrobenzene sulphonic acid model of acute colitis, we observed that mice treated with L. reuteri maintained SERT at the colon membrane compared with mice receiving phosphate buffered saline vehicle control. These data suggest that L. reuteri metabolites, including ethanol, can upregulate SERT and may be beneficial for maintaining intestinal homeostasis with respect to serotonin signalling.
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Affiliation(s)
- M Engevik
- Department of Pathology & Immunology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA
- Department of Regenerative Medicine & Cell Biology, Medical University of South Carolina, 173 Ashely Ave, BSB 626, Charleston, SC 29425, USA
| | - W Ruan
- Department of Pediatrics, Baylor College of Medicine, 6701 Fannin Street, Houston, TX 77030, USA
- Section of Gastroenterology, Hepatology, and Nutrition, Texas Children's Hospital, 6701 Fannin St, Houston, TX 77030, USA
| | - C Visuthranukul
- Department of Pathology & Immunology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA
- Pediatric Nutrition Research Unit, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Z Shi
- Department of Pathology & Immunology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA
- Department of Pathology, Texas Children's Hospital, 6621 Fannin St, Houston, TX 77030, USA
| | - K A Engevik
- Department of Molecular Virology & Microbiology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 7703, USA
| | - A C Engevik
- Departments of Surgery, Vanderbilt University Medical Center, 1211 Medical Center Dr, Nashville, TN 37232, USA
| | - R Fultz
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0625, USA
| | - D A Schady
- Department of Pathology & Immunology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA
- Department of Pathology, Texas Children's Hospital, 6621 Fannin St, Houston, TX 77030, USA
| | - J K Spinler
- Department of Pathology & Immunology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA
- Department of Pathology, Texas Children's Hospital, 6621 Fannin St, Houston, TX 77030, USA
| | - J Versalovic
- Department of Pathology & Immunology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA
- Department of Pathology, Texas Children's Hospital, 6621 Fannin St, Houston, TX 77030, USA
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13
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Bhat S, Niello M, Schicker K, Pifl C, Sitte HH, Freissmuth M, Sandtner W. Handling of intracellular K + determines voltage dependence of plasmalemmal monoamine transporter function. eLife 2021; 10:67996. [PMID: 34061030 PMCID: PMC8192120 DOI: 10.7554/elife.67996] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 05/30/2021] [Indexed: 12/16/2022] Open
Abstract
The concentrative power of the transporters for dopamine (DAT), norepinephrine (NET), and serotonin (SERT) is thought to be fueled by the transmembrane Na+ gradient, but it is conceivable that they can also tap other energy sources, for example, membrane voltage and/or the transmembrane K+ gradient. We have addressed this by recording uptake of endogenous substrates or the fluorescent substrate APP+(4-(4-dimethylamino)phenyl-1-methylpyridinium) under voltage control in cells expressing DAT, NET, or SERT. We have shown that DAT and NET differ from SERT in intracellular handling of K+. In DAT and NET, substrate uptake was voltage-dependent due to the transient nature of intracellular K+ binding, which precluded K+ antiport. SERT, however, antiports K+ and achieves voltage-independent transport. Thus, there is a trade-off between maintaining constant uptake and harvesting membrane potential for concentrative power, which we conclude to occur due to subtle differences in the kinetics of co-substrate ion binding in closely related transporters.
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Affiliation(s)
- Shreyas Bhat
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Marco Niello
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Klaus Schicker
- Division of Neurophysiology and Neuropharmacology, Centre for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Christian Pifl
- Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Harald H Sitte
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Walter Sandtner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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14
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Ihara M, Zhang H, Ihara MO, Kato D, Tanaka H. Proposal for fluorescence-based in vitro assay using human and zebrafish monoamine transporters to detect biological activities of antidepressants in wastewater. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 770:144665. [PMID: 33513512 DOI: 10.1016/j.scitotenv.2020.144665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/11/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
Antidepressants are among the most commonly detected pharmaceuticals in the aquatic environment. As they modulate neurotransmission in nervous systems, behavioural abnormalities among aquatic species are of concern. It is possible to measure the concentrations of selected antidepressants by chemical analysis, but other non-target antidepressants and active metabolites might also be present. Here, we propose an "in vitro monoamine transporter inhibition assay" to measure the biological activity of antidepressants, particularly monoamine transporter inhibitors, in wastewater. We used APP, a fluorescent substrate for monoamine transporters, to measure the activity of wastewater extracts at inhibiting APP uptake through the human serotonin transporter (hSERT), norepinephrine transporter (hNET), and dopamine transporter, and the zebrafish SERT (zSERT). We confirmed that the assay could measure the biological activity of test antidepressants. Interestingly, the IC50 values of antidepressants (the concentration that gave a 50% reduction of APP uptake) for the zSERT were smaller than those for the hSERT. For example, IC50 value of desipramine for the zSERT was 1/200 of that for the hSERT. These results indicate that antidepressants inhibited zSERT more strongly than hSERT. Then we applied the assay to extracts of effluent from municipal wastewater treatment plants and detected biological activity of antidepressants specifically against the hSERT, hNET, and zSERT for the first time. For the hSERT, antidepressant-equivalent quantities (EQs) ranged from 2.2 × 101 to 2.5 × 102 ng-clomipramine-EQ/L. For the hNET, EQs ranged from below limit of detection to 8.2 × 101 ng-desipramine-EQ/L. For the zSERT, EQs ranged from 2.8 × 102 to 3.3 × 102 ng-duloxetine-EQ/L. The in vitro monoamine transporter inhibition assay is thus useful for measuring the biological activity of antidepressants in the aquatic environment.
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Affiliation(s)
- Masaru Ihara
- Research Center for Environmental Quality Management, Kyoto University, 1-2 Yumihama, Otsu, Shiga 520-0811, Japan.
| | - Han Zhang
- Research Center for Environmental Quality Management, Kyoto University, 1-2 Yumihama, Otsu, Shiga 520-0811, Japan
| | - Mariko O Ihara
- Research Center for Environmental Quality Management, Kyoto University, 1-2 Yumihama, Otsu, Shiga 520-0811, Japan
| | - Daisuke Kato
- Research Center for Environmental Quality Management, Kyoto University, 1-2 Yumihama, Otsu, Shiga 520-0811, Japan
| | - Hiroaki Tanaka
- Research Center for Environmental Quality Management, Kyoto University, 1-2 Yumihama, Otsu, Shiga 520-0811, Japan
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15
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Ruchala I, Battisti UM, Nguyen VT, Chen RYT, Glennon RA, Eltit JM. Functional characterization of N-octyl 4-methylamphetamine variants and related bivalent compounds at the dopamine and serotonin transporters using Ca 2+ channels as sensors. Toxicol Appl Pharmacol 2021; 419:115513. [PMID: 33785354 PMCID: PMC8148225 DOI: 10.1016/j.taap.2021.115513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/21/2021] [Accepted: 03/25/2021] [Indexed: 10/21/2022]
Abstract
The early characterization of ligands at the dopamine and serotonin transporters, DAT and SERT, respectively, is important for drug discovery, forensic sciences, and drug abuse research. 4-Methyl amphetamine (4-MA) is a good example of an abused drug whose overdose can be fatal. It is a potent substrate at DAT and SERT where its simplest secondary amine (N-methyl 4-MA) retains substrate activity at them. In contrast, N-n-butyl 4-MA is very weak, therefore it was categorized as inactive at these transporters. Here, N-octyl 4-MA and other related compounds were synthesized, and their activities were evaluated at DAT and SERT. To expedite this endeavor, cells expressing DAT or SERT were co-transfected with a voltage-gated Ca2+ channel and, the genetically-encoded Ca2+ sensor, GCaMP6s. Control compounds and the newly synthesized molecules were tested on these cells using an automated multi-well fluorescence plate reader; substrates and inhibitors were identified successfully at DAT and SERT. N-Octyl 4-MA and three bivalent compounds were inhibitors at these transporters. These findings were validated by measuring Ca2+-mobilization using quantitative fluorescence microscopy. The bivalent molecules were the most potent of the series and were further characterized in an uptake-inhibition assay. Compared to cocaine, they showed comparable potency inhibiting uptake at DAT and higher potency at SERT. These observations support a previous hypothesis that amphetamine-related (and, here, N-extended alkyl and) bivalent arylalkylamine molecules are active at monoamine transporters, showing potent activity as reuptake inhibitors, and implicate the involvement of a distant auxiliary binding feature to account for their actions at DAT and SERT.
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Affiliation(s)
- Iwona Ruchala
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, United States of America
| | - Umberto M Battisti
- Deparment of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, United States of America
| | - Vy T Nguyen
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, United States of America
| | - Rita Yu-Tzu Chen
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, United States of America
| | - Richard A Glennon
- Deparment of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, United States of America
| | - Jose M Eltit
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, United States of America.
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16
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Whitaker DJ, Huang Z, Longbottom BW, Sala RL, Wu G, Scherman OA. Supramolecular hydrogels prepared from fluorescent alkyl pyridinium acrylamide monomers and CB[8]. Polym Chem 2021. [DOI: 10.1039/d0py01374a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Facile synthetic methodology unlocks alkyl pyridinium acrylamide monomers for use in the construction of cucurbit[8]uril mediated dynamic, fluorescent hydrogels.
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Affiliation(s)
- Daniel J. Whitaker
- Melville Laboratory for Polymer Synthesis
- Department of Chemistry
- University of Cambridge
- Cambridge
- UK
| | - Zehuan Huang
- Melville Laboratory for Polymer Synthesis
- Department of Chemistry
- University of Cambridge
- Cambridge
- UK
| | - Brooke W. Longbottom
- Melville Laboratory for Polymer Synthesis
- Department of Chemistry
- University of Cambridge
- Cambridge
- UK
| | - Renata L. Sala
- Melville Laboratory for Polymer Synthesis
- Department of Chemistry
- University of Cambridge
- Cambridge
- UK
| | - Guanglu Wu
- Melville Laboratory for Polymer Synthesis
- Department of Chemistry
- University of Cambridge
- Cambridge
- UK
| | - Oren A. Scherman
- Melville Laboratory for Polymer Synthesis
- Department of Chemistry
- University of Cambridge
- Cambridge
- UK
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17
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Organic Cation Transporters in the Lung-Current and Emerging (Patho)Physiological and Pharmacological Concepts. Int J Mol Sci 2020; 21:ijms21239168. [PMID: 33271927 PMCID: PMC7730617 DOI: 10.3390/ijms21239168] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/24/2020] [Accepted: 11/27/2020] [Indexed: 02/07/2023] Open
Abstract
Organic cation transporters (OCT) 1, 2 and 3 and novel organic cation transporters (OCTN) 1 and 2 of the solute carrier 22 (SLC22) family are involved in the cellular transport of endogenous compounds such as neurotransmitters, l-carnitine and ergothioneine. OCT/Ns have also been implicated in the transport of xenobiotics across various biological barriers, for example biguanides and histamine receptor antagonists. In addition, several drugs used in the treatment of respiratory disorders are cations at physiological pH and potential substrates of OCT/Ns. OCT/Ns may also be associated with the development of chronic lung diseases such as allergic asthma and chronic obstructive pulmonary disease (COPD) and, thus, are possible new drug targets. As part of the Special Issue "Physiology, Biochemistry and Pharmacology of Transporters for Organic Cations", this review provides an overview of recent findings on the (patho)physiological and pharmacological functions of organic cation transporters in the lung.
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18
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Fung TC, Vuong HE, Luna CD, Pronovost GN, Aleksandrova AA, Riley NG, Vavilina A, McGinn J, Rendon T, Forrest LR, Hsiao EY. Intestinal serotonin and fluoxetine exposure modulate bacterial colonization in the gut. Nat Microbiol 2019; 4:2064-2073. [PMID: 31477894 PMCID: PMC6879823 DOI: 10.1038/s41564-019-0540-4] [Citation(s) in RCA: 254] [Impact Index Per Article: 50.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 07/15/2019] [Indexed: 01/16/2023]
Abstract
The gut microbiota regulates levels of serotonin (5-hydroxytryptamine (5-HT)) in the intestinal epithelium and lumen1-5. However, whether 5-HT plays a functional role in bacteria from the gut microbiota remains unknown. We demonstrate that elevating levels of intestinal lumenal 5-HT by oral supplementation or genetic deficiency in the host 5-HT transporter (SERT) increases the relative abundance of spore-forming members of the gut microbiota, which were previously reported to promote host 5-HT biosynthesis. Within this microbial community, we identify Turicibacter sanguinis as a gut bacterium that expresses a neurotransmitter sodium symporter-related protein with sequence and structural homology to mammalian SERT. T. sanguinis imports 5-HT through a mechanism that is inhibited by the selective 5-HT reuptake inhibitor fluoxetine. 5-HT reduces the expression of sporulation factors and membrane transporters in T. sanguinis, which is reversed by fluoxetine exposure. Treating T. sanguinis with 5-HT or fluoxetine modulates its competitive colonization in the gastrointestinal tract of antibiotic-treated mice. In addition, fluoxetine reduces the membership of T. sanguinis in the gut microbiota of conventionally colonized mice. Host association with T. sanguinis alters intestinal expression of multiple gene pathways, including those important for lipid and steroid metabolism, with corresponding reductions in host systemic triglyceride levels and inguinal adipocyte size. Together, these findings support the notion that select bacteria indigenous to the gut microbiota signal bidirectionally with the host serotonergic system to promote their fitness in the intestine.
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Affiliation(s)
- Thomas C. Fung
- Department of Integrative Biology & Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA,Correspondence to: and
| | - Helen E. Vuong
- Department of Integrative Biology & Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Christopher D.G. Luna
- Department of Integrative Biology & Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Geoffrey N. Pronovost
- Department of Integrative Biology & Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Antoniya A. Aleksandrova
- Computational Structural Biology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Noah G. Riley
- Computational Structural Biology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Anastasia Vavilina
- Department of Integrative Biology & Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Julianne McGinn
- Department of Integrative Biology & Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Tomiko Rendon
- Department of Integrative Biology & Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Lucy R. Forrest
- Computational Structural Biology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Elaine Y. Hsiao
- Department of Integrative Biology & Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA,Correspondence to: and
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19
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Iyer KA, Alix K, Eltit JM, Solis E, Pan X, Argade MD, Khatri S, De Felice LJ, Sweet DH, Schulte MK, Dukat M. Multi-modal antidepressant-like action of 6- and 7-chloro-2-aminodihydroquinazolines in the mouse tail suspension test. Psychopharmacology (Berl) 2019; 236:2093-2104. [PMID: 30805668 DOI: 10.1007/s00213-019-05203-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 02/14/2019] [Indexed: 01/08/2023]
Abstract
RATIONALE 2-Amino-6-chloro-3,4-dihydroquinazoline (e.g., A6CDQ) represents a novel putative antidepressant originally thought to act through a 5-HT3 serotonin receptor antagonist mechanism. Here, we investigated this further by examining a positional isomer of A6CDQ (i.e., A7CDQ). MATERIALS AND METHODS 5-HT3 receptor and transporter activity (uptake-1 and uptake-2) were investigated using a variety of in vitro assays and the in vivo mouse tail suspension test (TST). RESULTS Although A7CDQ binds at 5-HT3 receptors with low affinity (Ki = 1975 nM) compared to A6CDQ (Ki = 80 nM), it retained 5-HT3 receptor antagonist action (IC50 = 5.77 and 0.26 μM, respectively). In the mouse TST A7CDQ produced antidepressant-like actions (ED50 = 0.09 mg/kg) comparable to that of A6CDQ. In addition, A6CDQ was found to be a 5-HT releasing agent (Km = 2.8 μM) at hSERT and a reuptake inhibitor (IC50 = 1.8 μM) at hNET, whereas A7CDQ was a weak reuptake inhibitor (Km = 43.6 μM) at SERT but a releasing agent (EC50 = 3.3 μM) at hNET. Moreover, A6CDQ and A7CDQ were potent inhibitors of uptake-2 (e.g.; OCT3 IC50 = 3.9 and 5.9 μM, respectively). CONCLUSIONS A simple shift of a substituent in a common quinazoline scaffold from one position to another (i.e., a chloro group from the 6- to the 7-position) resulted in a common action in the TST but via a somewhat different mechanism. A6CDQ and A7CDQ might represent the first members of a new class of potential antidepressants with a unique multi-modal mechanism of action.
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Affiliation(s)
- Kavita A Iyer
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, PO Box 980540, Richmond, VA, 23298-540, USA
| | - Katie Alix
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, PO Box 980540, Richmond, VA, 23298-540, USA
| | - Jose M Eltit
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Ernesto Solis
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Xiaolei Pan
- Department of Pharmaceutics, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Malaika D Argade
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, PO Box 980540, Richmond, VA, 23298-540, USA
| | - Shailesh Khatri
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of Sciences, Philadelphia, PA, 19104, USA
| | - Louis J De Felice
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Douglas H Sweet
- Department of Pharmaceutics, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Marvin K Schulte
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, Kasiska Division of Health Sciences, Idaho State University, Pocatello, ID, 83209, USA
| | - Małgorzata Dukat
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, PO Box 980540, Richmond, VA, 23298-540, USA.
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20
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Moerke MJ, Ananthan S, Banks ML, Eltit JM, Freitas KC, Johnson AR, Saini SK, Steele TWE, Negus SS. Interactions between Cocaine and the Putative Allosteric Dopamine Transporter Ligand SRI-31142. J Pharmacol Exp Ther 2018; 367:222-233. [PMID: 30150482 PMCID: PMC6170971 DOI: 10.1124/jpet.118.250902] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/23/2018] [Indexed: 11/22/2022] Open
Abstract
Drugs that inhibit the dopamine (DA) transporter (DAT) include both therapeutic agents and abused drugs. Recent studies identified a novel series of putative allosteric DAT inhibitors, but the in vivo effects of these compounds are unknown. This study examined the abuse-related behavioral and neurochemical effects produced in rats by SRI-31142 [2-(7-methylimidazo[1,2-a]pyridin-6-yl)-N-(2-phenyl-2-(pyridin-4-yl)ethyl)quinazolin-4-amine], one compound from this series. In behavioral studies, intracranial self-stimulation (ICSS) was used to compare the effects produced by SRI-31142, the abused and nonselective DAT inhibitor cocaine, and the selective DAT inhibitor GBR-12935 [1-[2-(diphenylmethoxy)ethyl]-4-(3-phenylpropyl)piperazine]. In neurochemical studies, in vivo microdialysis was used to compare the effects of SRI-31142 and cocaine on levels of DA and serotonin in nucleus accumbens (NAc). The effects of SRI-31142 in combination with cocaine were also examined in both procedures. In contrast to cocaine and GBR-12935, SRI-31142 failed to produce abuse-related increases in ICSS or NAc DA; instead, SRI-31142 only decreased ICSS and NAc DA at a dose that was also sufficient to block cocaine-induced increases in ICSS and NAc DA. Pharmacokinetic studies suggested low but adequate brain penetration of SRI-31142, in vitro binding studies failed to identify likely non-DAT targets, and in vitro functional assays failed to confirm DA uptake inhibition in an assay of DAT-mediated fluorescent signals in live cells. These results indicate that SRI-31142 does not produce cocaine-like abuse-related effects in rats. SRI-31142 may have utility to block cocaine effects and may warrant further study as a candidate pharmacotherapy; however, the role of DAT in mediating these effects is unclear, and side effects may be a limiting factor.
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Affiliation(s)
- Megan J Moerke
- Departments of Pharmacology and Toxicology (M.J.M., M.L.B., K.C.F., A.R.J., S.S.N.) and Physiology and Biophysics (J.M.E., T.W.E.S.), Virginia Commonwealth University, Richmond, Virginia; and Chemistry Department, Drug Discovery Division, Southern Research, Birmingham, Alabama (S.A., S.K.S.)
| | - Subramaniam Ananthan
- Departments of Pharmacology and Toxicology (M.J.M., M.L.B., K.C.F., A.R.J., S.S.N.) and Physiology and Biophysics (J.M.E., T.W.E.S.), Virginia Commonwealth University, Richmond, Virginia; and Chemistry Department, Drug Discovery Division, Southern Research, Birmingham, Alabama (S.A., S.K.S.)
| | - Matthew L Banks
- Departments of Pharmacology and Toxicology (M.J.M., M.L.B., K.C.F., A.R.J., S.S.N.) and Physiology and Biophysics (J.M.E., T.W.E.S.), Virginia Commonwealth University, Richmond, Virginia; and Chemistry Department, Drug Discovery Division, Southern Research, Birmingham, Alabama (S.A., S.K.S.)
| | - Jose M Eltit
- Departments of Pharmacology and Toxicology (M.J.M., M.L.B., K.C.F., A.R.J., S.S.N.) and Physiology and Biophysics (J.M.E., T.W.E.S.), Virginia Commonwealth University, Richmond, Virginia; and Chemistry Department, Drug Discovery Division, Southern Research, Birmingham, Alabama (S.A., S.K.S.)
| | - Kelen C Freitas
- Departments of Pharmacology and Toxicology (M.J.M., M.L.B., K.C.F., A.R.J., S.S.N.) and Physiology and Biophysics (J.M.E., T.W.E.S.), Virginia Commonwealth University, Richmond, Virginia; and Chemistry Department, Drug Discovery Division, Southern Research, Birmingham, Alabama (S.A., S.K.S.)
| | - Amy R Johnson
- Departments of Pharmacology and Toxicology (M.J.M., M.L.B., K.C.F., A.R.J., S.S.N.) and Physiology and Biophysics (J.M.E., T.W.E.S.), Virginia Commonwealth University, Richmond, Virginia; and Chemistry Department, Drug Discovery Division, Southern Research, Birmingham, Alabama (S.A., S.K.S.)
| | - Surendra K Saini
- Departments of Pharmacology and Toxicology (M.J.M., M.L.B., K.C.F., A.R.J., S.S.N.) and Physiology and Biophysics (J.M.E., T.W.E.S.), Virginia Commonwealth University, Richmond, Virginia; and Chemistry Department, Drug Discovery Division, Southern Research, Birmingham, Alabama (S.A., S.K.S.)
| | - Tyler W E Steele
- Departments of Pharmacology and Toxicology (M.J.M., M.L.B., K.C.F., A.R.J., S.S.N.) and Physiology and Biophysics (J.M.E., T.W.E.S.), Virginia Commonwealth University, Richmond, Virginia; and Chemistry Department, Drug Discovery Division, Southern Research, Birmingham, Alabama (S.A., S.K.S.)
| | - S Stevens Negus
- Departments of Pharmacology and Toxicology (M.J.M., M.L.B., K.C.F., A.R.J., S.S.N.) and Physiology and Biophysics (J.M.E., T.W.E.S.), Virginia Commonwealth University, Richmond, Virginia; and Chemistry Department, Drug Discovery Division, Southern Research, Birmingham, Alabama (S.A., S.K.S.)
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Mapa MST, Le VQ, Wimalasena K. Characteristics of the mitochondrial and cellular uptake of MPP+, as probed by the fluorescent mimic, 4'I-MPP. PLoS One 2018; 13:e0197946. [PMID: 30138351 PMCID: PMC6107127 DOI: 10.1371/journal.pone.0197946] [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] [Received: 05/09/2018] [Accepted: 08/06/2018] [Indexed: 11/24/2022] Open
Abstract
The discovery that 1-methyl-4-phenylpyridinium (MPP+) selectively destroys dopaminergic neurons and causes Parkinson’s disease (PD) symptoms in mammals has strengthened the environmental hypothesis of PD. The current model for the dopaminergic toxicity of MPP+ is centered on its uptake into dopaminergic neurons, accumulation into the mitochondria, inhibition of the complex-I leading to ATP depletion, increased reactive oxygen species (ROS) production, and apoptotic cell death. However, some aspects of this mechanism and the details of the cellular and mitochondrial accumulation of MPP+ are still poorly understood. The aim of this study was to characterize a structural and functional MPP+ mimic which is suitable to study the cellular distribution and mitochondrial uptake of MPP+ in live cells and use it to identify the molecular details of these processes to advance the understanding of the mechanism of the selective dopaminergic toxicity of MPP+. Here we report the characterization of the fluorescent MPP+ derivative, 1-methyl-4-(4'-iodophenyl)pyridinium (4'I-MPP+), as a suitable candidate for this purpose. Using this novel probe, we show that cytosolic/mitochondrial Ca2+ play a critical role through the sodium-calcium exchanger (NCX) in the mitochondrial and cellular accumulation of MPP+ suggesting for the first time that MPP+ and related mitochondrial toxins may also exert their toxic effects through the perturbation of Ca2+ homeostasis in dopaminergic cells. We also found that the specific mitochondrial NCX (mNCX) inhibitors protect dopaminergic cells from the MPP+ and 4'I-MPP+ toxicity, most likely through the inhibition of the mitochondrial uptake, which could potentially be exploited for the development of pharmacological agents to protect the central nervous system (CNS) dopaminergic neurons from PD-causing environmental toxins.
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Affiliation(s)
- Mapa S T Mapa
- Department of Chemistry, Wichita State University, Wichita, Kansas, United States of America
| | - Viet Q Le
- Department of Chemistry, Wichita State University, Wichita, Kansas, United States of America
| | - Kandatege Wimalasena
- Department of Chemistry, Wichita State University, Wichita, Kansas, United States of America
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Evidence for PMAT- and OCT-like biogenic amine transporters in a probiotic strain of Lactobacillus: Implications for interkingdom communication within the microbiota-gut-brain axis. PLoS One 2018; 13:e0191037. [PMID: 29324833 PMCID: PMC5764344 DOI: 10.1371/journal.pone.0191037] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 12/27/2017] [Indexed: 12/12/2022] Open
Abstract
The ability of prokaryotic microbes to produce and respond to neurochemicals that are more often associated with eukaryotic systems is increasingly recognized through the concept of microbial endocrinology. Most studies have described the phenomena of neurochemical production by bacteria, but there remains an incomplete understanding of the mechanisms by which microbe- or host-derived neuroactive substances can be recognized by bacteria. Based on the evolutionary origins of eukaryotic solute carrier transporters, we hypothesized that bacteria may possess an analogous uptake function for neuroactive biogenic amines. Using specific fluorescence-based assays, Lactobacillus salivarius biofilms appear to express both plasma membrane monoamine transporter (PMAT)- and organic cation transporter (OCT)-like uptake of transporter-specific fluorophores. This phenomenon is not distributed throughout the genus Lactobacillus as L. rhamnosus biofilms did not take up these fluorophores. PMAT probe uptake into L. salivarius biofilms was attenuated by the protonophore CCCP, the cation transport inhibitor decynium-22, and the natural substrates norepinephrine, serotonin and fluoxetine. These results provide the first evidence, to our knowledge, for the existence of PMAT- and OCT-like uptake systems in a bacterium. They also suggest the existence of a hitherto unrecognized mechanism by which a probiotic bacterium may interact with host signals and may provide a means to examine microbial endocrinology-based interactions in health and disease that are part of the larger microbiota-gut-brain axis.
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Novel serotonin transporter regulators: Natural aristolane- and nardosinane- types of sesquiterpenoids from Nardostachys chinensis Batal. Sci Rep 2017; 7:15114. [PMID: 29118341 PMCID: PMC5678126 DOI: 10.1038/s41598-017-15483-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 10/27/2017] [Indexed: 11/30/2022] Open
Abstract
Serotonin transporter (SERT) is a classic target of drug discovery for neuropsychiatric and digestive disorders, and against those disorders, plants of Nardostachys genus have been valued for centuries in the systems of Traditional Chinese Medicine, Ayurvedic and Unani. Herein, chemical investigation on the roots and rhizomes of Nardostachys chinensis Batal. led to the isolation of forty sesquiterpenoids including six new aristolane-type sesquiterpenoids and six new nardosinane-type sesquiterprenoids. Their structures were elucidated by extensive spectroscopic methods, combined with analyses of circular dichroism and single-crystal X-ray diffraction data. To explore natural product scaffolds with SERT regulating activity, a high-content assay for measurement of SERT function in vitro was conducted to evaluate the SERT regulating properties of these isolates. In conclusion, eleven compounds could be potential natural product scaffolds for developing drug candidates targeting SERT. Among which, kanshone C of aristolane-type sesquiterpenoid inhibited SERT most strongly, while desoxo-nachinol A of nardosinane-type sesquiterpenoid instead enhanced SERT potently.
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N-Alkylated Analogs of 4-Methylamphetamine (4-MA) Differentially Affect Monoamine Transporters and Abuse Liability. Neuropsychopharmacology 2017; 42:1950-1961. [PMID: 28530234 PMCID: PMC5561352 DOI: 10.1038/npp.2017.98] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 05/04/2017] [Accepted: 05/12/2017] [Indexed: 01/22/2023]
Abstract
Clandestine chemists synthesize novel stimulant drugs by exploiting structural templates known to target monoamine transporters for dopamine, norepinephrine, and serotonin (DAT, NET, and SERT, respectively). 4-Methylamphetamine (4-MA) is an emerging drug of abuse that interacts with transporters, but limited structure-activity data are available for its analogs. Here we employed uptake and release assays in rat brain synaptosomes, voltage-clamp current measurements in cells expressing transporters, and calcium flux assays in cells coexpressing transporters and calcium channels to study the effects of increasing N-alkyl chain length of 4-MA on interactions at DAT, NET, and SERT. In addition, we performed intracranial self-stimulation in rats to understand how the chemical modifications affect abuse liability. All 4-MA analogs inhibited uptake at DAT, NET, and SERT, but lengthening the amine substituent from methyl to ethyl, propyl, and butyl produced a stepwise decrease in potency. N-methyl 4-MA was an efficacious substrate-type releaser at DAT that evoked an inward depolarizing current and calcium influx, whereas other analogs did not exhibit these effects. N-methyl and N-ethyl 4-MA were substrates at NET, whereas N-propyl and N-butyl 4-MA were not. All analogs acted as SERT substrates, though N-butyl 4-MA had very weak effects. Intracranial self-stimulation in rats showed that elongating the N-alkyl chain decreased abuse-related effects in vivo that appeared to parallel reductions in DAT activity. Overall, converging lines of evidence show that lengthening the N-alkyl substituent of 4-MA reduces potency to inhibit transporters, eliminates substrate activity at DAT and NET, and decreases abuse liability of the compounds.
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Wimalasena K. Current Status, Gaps, and Weaknesses of the Mechanism of Selective Dopaminergic Toxicity of MPTP/MPP +. ADVANCES IN MOLECULAR TOXICOLOGY 2017. [DOI: 10.1016/b978-0-12-812522-9.00003-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Dissociable effects of the prodrug phendimetrazine and its metabolite phenmetrazine at dopamine transporters. Sci Rep 2016; 6:31385. [PMID: 27514281 PMCID: PMC4981850 DOI: 10.1038/srep31385] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 07/19/2016] [Indexed: 11/28/2022] Open
Abstract
Phendimetrazine (PDM) is a clinically available anorectic and a candidate pharmacotherapy for cocaine addiction. PDM has been hypothesized to function as a prodrug that requires metabolism to the amphetamine-like monoamine transporter substrate phenmetrazine (PM) to produce its pharmacological effects; however, whether PDM functions as an inactive prodrug or has pharmacological activity on its own remains unclear. The study aim was to determine PDM pharmacological mechanisms using electrophysiological, neurochemical, and behavioral procedures. PDM blocked the endogenous basal hDAT (human dopamine transporter) current in voltage-clamped (−60 mV) oocytes consistent with a DAT inhibitor profile, whereas its metabolite PM induced an inward hDAT current consistent with a DAT substrate profile. PDM also attenuated the PM-induced inward current during co-application, providing further evidence that PDM functions as a DAT inhibitor. PDM increased nucleus accumbens dopamine levels and facilitated electrical brain stimulation reinforcement within 10 min in rats, providing in vivo evidence supporting PDM pharmacological activity. These results demonstrate that PDM functions as a DAT inhibitor that may also interact with the pharmacological effects of its metabolite PM. Overall, these results suggest a novel mechanism for PDM therapeutic effects via initial PDM DAT inhibition followed by PM DAT substrate-induced dopamine release.
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Wu HH, Chen YP, Ying SS, Zhang P, Xu YT, Gao XM, Zhu Y. Dinardokanshones A and B, two unique sesquiterpene dimers from the roots and rhizomes of Nardostachys chinensis. Tetrahedron Lett 2015. [DOI: 10.1016/j.tetlet.2015.08.079] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Luk B, Mohammed M, Liu F, Lee FJS. A Physical Interaction between the Dopamine Transporter and DJ-1 Facilitates Increased Dopamine Reuptake. PLoS One 2015; 10:e0136641. [PMID: 26305376 PMCID: PMC4549284 DOI: 10.1371/journal.pone.0136641] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 08/06/2015] [Indexed: 11/18/2022] Open
Abstract
The regulation of the dopamine transporter (DAT) impacts extracellular dopamine levels after release from dopaminergic neurons. Furthermore, a variety of protein partners have been identified that can interact with and modulate DAT function. In this study we show that DJ-1 can potentially modulate DAT function. Co-expression of DAT and DJ-1 in HEK-293T cells leads to an increase in [3H] dopamine uptake that does not appear to be mediated by increased total DAT expression but rather through an increase in DAT cell surface localization. In addition, through a series of GST affinity purifications and co-immunoprecipitations, we provide evidence that the DAT can be found in a complex with DJ-1, which involve distinct regions within both DAT and DJ-1. Using in vitro binding experiments we also show that this complex can be formed in part by a direct interaction between DAT and DJ-1. Co-expression of a mini-gene that can disrupt the DAT/DJ-1 complex appears to block the increase in [3H] dopamine uptake by DJ-1. Mutations in DJ-1 have been linked to familial forms of Parkinson’s disease, yet the normal physiological function of DJ-1 remains unclear. Our study suggests that DJ-1 may also play a role in regulating dopamine levels by modifying DAT activity.
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Affiliation(s)
- Beryl Luk
- Faculty of Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Mohinuddin Mohammed
- Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada
| | - Fang Liu
- Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada
| | - Frank J. S. Lee
- Faculty of Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
- * E-mail:
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A novel sesquiterpene and three new phenolic compounds from the rhizomes of Acorus tatarinowii Schott. Bioorg Med Chem Lett 2015; 25:4214-8. [PMID: 26296476 DOI: 10.1016/j.bmcl.2015.08.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 06/30/2015] [Accepted: 08/03/2015] [Indexed: 11/23/2022]
Abstract
A novel sesquiterpene with an unprecedented epoxy lactone skeleton, named tatarinolactone, together with two new amides, a new biphenylpropanoid and two known lignans were isolated from the rhizomes of Acorus tatarinowii Schott. Their structures were identified as 6,7,8-trihydroxy-4α-isobutyl-4,7-dimethylhexahydro-6,8α-epoxychromen-2(3H)-one (1), (E)-methyl 4-[3-(4-hydroxy-3-methoxyphenyl)acrylamido]butanoate (2), (Z)-methyl 4-[3-(4-hydroxy-3-methoxyphenyl)acrylamido]butanoate enol isomer (3), (R)-4-hydroxy-3-[1-hydroxy-3-(4-hydroxy-3-methoxyphenyl)propan-2-yl]-5-methoxybenzoic acid (4), (2S,3R)-ceplignan (5), and (2R,3S)-ceplignan (6), respectively, based on extensive spectroscopic analysis and by comparison to the known compounds. To test their effects on serotonin transporters, a high content assay using hSERT-HEK293 cell line was adopted. Results indicated that compounds 1 and 4 significantly inhibited SERT activity, while compounds 2, 3, 5, and 6 significantly enhanced SERT activity, which partly explain the traditional uses of the rhizomes of Acorus tatarinowii Schott in treatments of neuropsychiatric and digestive disorders.
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30
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Agnihotri H, Vasu AK, Palakollu V, Kanvah S. Neutral and cationic pyridylbutadienes: solvatochromism and fluorescence response with sodium cholate. Photochem Photobiol Sci 2015; 14:2159-67. [DOI: 10.1039/c5pp00179j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Characteristic ICT emission in solvents and enhanced emission intensity in presence of sodium cholate.
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Affiliation(s)
- Harsha Agnihotri
- Department of Chemistry
- Indian Institute of Technology Gandhinagar
- Ahmedabad 382 424
- India
| | - Anuji K. Vasu
- Department of Chemistry
- Indian Institute of Technology Gandhinagar
- Ahmedabad 382 424
- India
| | | | - Sriram Kanvah
- Department of Chemistry
- Indian Institute of Technology Gandhinagar
- Ahmedabad 382 424
- India
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31
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Kurps J, Broeke JH, Cijsouw T, Kompatscher A, van Weering JRT, de Wit H. Quantitative image analysis tool to study the plasma membrane localization of proteins and cortical actin in neuroendocrine cells. J Neurosci Methods 2014; 236:1-10. [PMID: 25109903 DOI: 10.1016/j.jneumeth.2014.07.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 07/28/2014] [Accepted: 07/29/2014] [Indexed: 11/15/2022]
Abstract
BACKGROUND Adrenal chromaffin cells are a widely used model system to study regulated exocytosis and other membrane-associated processes. Alterations in the amount and localization of the proteins involved in these processes can be visualized with fluorescent probes that report the effect of different stimuli or genetic modifications. However, the quantitative analysis of such images remains difficult, especially when focused on specific locations, such as the plasma membrane. NEW METHOD We developed an image analysis algorithm, named plasma membrane analysis in chromaffin cells (PlasMACC). PlasMACC enables automatic detection of the plasma membrane region and quantitative analysis of multi-fluorescent signals from spherical cells. PlasMACC runs in the image analysis software ImageJ environment, it is user-friendly and freely available. RESULTS PlasMACC delivers detailed information about intensity, thickness and density of fluorescent signals at the plasma membrane of both living and fixed cells. Individual signals can be compared between cells and different signals within one cell can be correlated. PlasMACC can process conventional laser-scanning confocal images as well as data obtained by super-resolution methods such as structured illumination microscopy. COMPARISON WITH EXISTING METHOD(S) By comparing PlasMACC to methods currently used in the field, we show more consistent quantitative data due to the fully automated algorithm. PlasMACC also provides an expanded set of novel analysis parameters. CONCLUSION PlasMACC enables a detailed quantification of fluorescent signals at the plasma membrane of spherical cells in an unbiased and reliable fashion.
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Affiliation(s)
- Julia Kurps
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV Amsterdam, Netherlands
| | - Jurjen H Broeke
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV Amsterdam, Netherlands
| | - Tony Cijsouw
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV Amsterdam, Netherlands
| | - Andreas Kompatscher
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV Amsterdam, Netherlands
| | - Jan R T van Weering
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV Amsterdam, Netherlands.
| | - Heidi de Wit
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV Amsterdam, Netherlands
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Ruchala I, Cabra V, Solis E, Glennon RA, De Felice LJ, Eltit JM. Electrical coupling between the human serotonin transporter and voltage-gated Ca(2+) channels. Cell Calcium 2014; 56:25-33. [PMID: 24854234 DOI: 10.1016/j.ceca.2014.04.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/18/2014] [Accepted: 04/19/2014] [Indexed: 10/25/2022]
Abstract
Monoamine transporters have been implicated in dopamine or serotonin release in response to abused drugs such as methamphetamine or ecstasy (MDMA). In addition, monoamine transporters show substrate-induced inward currents that may modulate excitability and Ca(2+) mobilization, which could also contribute to neurotransmitter release. How monoamine transporters modulate Ca(2+) permeability is currently unknown. We investigate the functional interaction between the human serotonin transporter (hSERT) and voltage-gated Ca(2+) channels (CaV). We introduce an excitable expression system consisting of cultured muscle cells genetically engineered to express hSERT. Both 5HT and S(+)MDMA depolarize these cells and activate the excitation-contraction (EC)-coupling mechanism. However, hSERT substrates fail to activate EC-coupling in CaV1.1-null muscle cells, thus implicating Ca(2+) channels. CaV1.3 and CaV2.2 channels are natively expressed in neurons. When these channels are co-expressed with hSERT in HEK293T cells, only cells expressing the lower-threshold L-type CaV1.3 channel show Ca(2+) transients evoked by 5HT or S(+)MDMA. In addition, the electrical coupling between hSERT and CaV1.3 takes place at physiological 5HT concentrations. The electrical coupling between monoamine neurotransmitter transporters and Ca(2+) channels such as CaV1.3 is a novel mechanism by which endogenous substrates (neurotransmitters) or exogenous substrates (like ecstasy) could modulate Ca(2+)-driven signals in excitable cells.
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Affiliation(s)
- Iwona Ruchala
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Vanessa Cabra
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Ernesto Solis
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Richard A Glennon
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Louis J De Felice
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Jose M Eltit
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA 23298, United States.
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Fraser R, Chen Y, Guptaroy B, Luderman KD, Stokes SL, Beg A, DeFelice LJ, Gnegy ME. An N-terminal threonine mutation produces an efflux-favorable, sodium-primed conformation of the human dopamine transporter. Mol Pharmacol 2014; 86:76-85. [PMID: 24753048 DOI: 10.1124/mol.114.091926] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The dopamine transporter (DAT) reversibly transports dopamine (DA) through a series of conformational transitions. Alanine (T62A) or aspartate (T62D) mutagenesis of Thr62 revealed T62D-human (h)DAT partitions in a predominately efflux-preferring conformation. Compared with wild-type (WT), T62D-hDAT exhibits reduced [(3)H]DA uptake and enhanced baseline DA efflux, whereas T62A-hDAT and WT-hDAT function in an influx-preferring conformation. We now interrogate the basis of the mutants' altered function with respect to membrane conductance and Na(+) sensitivity. The hDAT constructs were expressed in Xenopus oocytes to investigate if heightened membrane potential would explain the efflux characteristics of T62D-hDAT. In the absence of substrate, all constructs displayed identical resting membrane potentials. Substrate-induced inward currents were present in oocytes expressing WT- and T62A-hDAT but not T62D-hDAT, suggesting equal bidirectional ion flow through T62D-hDAT. Utilization of the fluorescent DAT substrate ASP(+) [4-(4-(dimethylamino)styryl)-N-methylpyridinium] revealed that T62D-hDAT accumulates substrate in human embryonic kidney (HEK)-293 cells when the substrate is not subject to efflux. Extracellular sodium (Na(+) e) replacement was used to evaluate sodium gradient requirements for DAT transport functions. The EC50 for Na(+) e stimulation of [(3)H]DA uptake was identical in all constructs expressed in HEK-293 cells. As expected, decreasing [Na(+)]e stimulated [(3)H]DA efflux in WT- and T62A-hDAT cells. Conversely, the elevated [(3)H]DA efflux in T62D-hDAT cells was independent of Na(+) e and commensurate with [(3)H]DA efflux attained in WT-hDAT cells, either by removal of Na(+) e or by application of amphetamine. We conclude that T62D-hDAT represents an efflux-willing, Na(+)-primed orientation-possibly representing an experimental model of the conformational impact of amphetamine exposure to hDAT.
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Affiliation(s)
- Rheaclare Fraser
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (R.F., B.G., K.D.L., S.L.S., A.B., M.E.G.); and Departments of Psychiatry (Y.C.) and Physiology and Biophysics (L.J.D.), Virginia Commonwealth University, Richmond, Virginia
| | - Yongyue Chen
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (R.F., B.G., K.D.L., S.L.S., A.B., M.E.G.); and Departments of Psychiatry (Y.C.) and Physiology and Biophysics (L.J.D.), Virginia Commonwealth University, Richmond, Virginia
| | - Bipasha Guptaroy
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (R.F., B.G., K.D.L., S.L.S., A.B., M.E.G.); and Departments of Psychiatry (Y.C.) and Physiology and Biophysics (L.J.D.), Virginia Commonwealth University, Richmond, Virginia
| | - Kathryn D Luderman
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (R.F., B.G., K.D.L., S.L.S., A.B., M.E.G.); and Departments of Psychiatry (Y.C.) and Physiology and Biophysics (L.J.D.), Virginia Commonwealth University, Richmond, Virginia
| | - Stephanie L Stokes
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (R.F., B.G., K.D.L., S.L.S., A.B., M.E.G.); and Departments of Psychiatry (Y.C.) and Physiology and Biophysics (L.J.D.), Virginia Commonwealth University, Richmond, Virginia
| | - Asim Beg
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (R.F., B.G., K.D.L., S.L.S., A.B., M.E.G.); and Departments of Psychiatry (Y.C.) and Physiology and Biophysics (L.J.D.), Virginia Commonwealth University, Richmond, Virginia
| | - Louis J DeFelice
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (R.F., B.G., K.D.L., S.L.S., A.B., M.E.G.); and Departments of Psychiatry (Y.C.) and Physiology and Biophysics (L.J.D.), Virginia Commonwealth University, Richmond, Virginia
| | - Margaret E Gnegy
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan (R.F., B.G., K.D.L., S.L.S., A.B., M.E.G.); and Departments of Psychiatry (Y.C.) and Physiology and Biophysics (L.J.D.), Virginia Commonwealth University, Richmond, Virginia
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Wilson JN, Ladefoged LK, Babinchak WM, Schiøtt B. Binding-induced fluorescence of serotonin transporter ligands: A spectroscopic and structural study of 4-(4-(dimethylamino)phenyl)-1-methylpyridinium (APP(+)) and APP(+) analogues. ACS Chem Neurosci 2014; 5:296-304. [PMID: 24460204 DOI: 10.1021/cn400230x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The binding-induced fluorescence of 4-(4-(dimethylamino)-phenyl)-1-methylpyridinium (APP(+)) and two new serotonin transporter (SERT)-binding fluorescent analogues, 1-butyl-4-[4-(1-dimethylamino)phenyl]-pyridinium bromide (BPP(+)) and 1-methyl-4-[4-(1-piperidinyl)phenyl]-pyridinium (PPP(+)), has been investigated. Optical spectroscopy reveals that these probes are highly sensitive to their chemical microenvironment, responding to variations in polarity with changes in transition energies and responding to changes in viscosity or rotational freedom with emission enhancements. Molecular docking calculations reveal that the probes are able to access the nonpolar and conformationally restrictive binding pocket of SERT. As a result, the probes exhibit previously not identified binding-induced turn-on emission that is spectroscopically distinct from dyes that have accumulated intracellularly. Thus, binding and transport dynamics of SERT ligands can be resolved both spatially and spectroscopically.
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Affiliation(s)
- James N. Wilson
- Department of Chemistry, University of Miami, Coral Gables, Florida 33124, United States
| | - Lucy Kate Ladefoged
- inSPIN
and iNANO Centers, Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
| | - W. Michael Babinchak
- Department of Chemistry, University of Miami, Coral Gables, Florida 33124, United States
| | - Birgit Schiøtt
- inSPIN
and iNANO Centers, Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
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Bernstein AI, Stout KA, Miller GW. The vesicular monoamine transporter 2: an underexplored pharmacological target. Neurochem Int 2014; 73:89-97. [PMID: 24398404 DOI: 10.1016/j.neuint.2013.12.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 12/06/2013] [Accepted: 12/09/2013] [Indexed: 12/21/2022]
Abstract
Active transport of neurotransmitters into synaptic vesicles is required for their subsequent exocytotic release. In the monoamine system, this process is carried out by the vesicular monoamine transporters (VMAT1 and VMAT2). These proteins are responsible for vesicular packaging of dopamine, norepinephrine, serotonin, and histamine. These proteins are essential for proper neuronal function; however, compared to their plasma membrane counterparts, there are few drugs available that target these vesicular proteins. This is partly due to the added complexity of crossing the plasma membrane, but also to the technical difficulty of assaying for vesicular uptake in high throughput. Until recently, reagents to enable high throughput screening for function of these vesicular neurotransmitter transporters have not been available. Fortunately, novel compounds and methods are now making such screening possible; thus, a renewed focus on these transporters as potential targets is timely and necessary.
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Affiliation(s)
- Alison I Bernstein
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Kristen A Stout
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Gary W Miller
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA; Center for Neurodegenerative Diseases, Emory University, Atlanta, GA 30322, USA; Department of Pharmacology, Emory University, Atlanta, GA 30322, USA; Department of Neurology, Emory University, Atlanta, GA 30322, USA.
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Hansen CS, Kirk BB, Blanksby SJ, Trevitt AJ. Ultraviolet Photodissociation of the N-Methylpyridinium Ion: Action Spectroscopy and Product Characterization. J Phys Chem A 2013; 117:10839-46. [DOI: 10.1021/jp4075515] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christopher S. Hansen
- ARC Centre of Excellence
for Free Radical Chemistry and Biotechnology and School of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Benjamin B. Kirk
- ARC Centre of Excellence
for Free Radical Chemistry and Biotechnology and School of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Stephen J. Blanksby
- ARC Centre of Excellence
for Free Radical Chemistry and Biotechnology and School of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Adam J. Trevitt
- ARC Centre of Excellence
for Free Radical Chemistry and Biotechnology and School of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia
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37
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Hu G, Henke A, Karpowicz RJ, Sonders MS, Farrimond F, Edwards R, Sulzer D, Sames D. New fluorescent substrate enables quantitative and high-throughput examination of vesicular monoamine transporter 2 (VMAT2). ACS Chem Biol 2013; 8:1947-54. [PMID: 23859623 DOI: 10.1021/cb400259n] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Vesicular monoamine transporter 2 (VMAT2) is an essential component of the monoaminergic neurotransmission system in the brain as it transports monoamine neurotransmitters from the neuronal cytosol into the synaptic vesicles and thus contributes to modulation of neurotransmitter release. Considering the continuing interest in VMAT2 as a drug target, as well as a target for the design of imaging probes, we have developed a fluorescent substrate well suited for the study of VMAT2 in cell culture. Herein, we report the synthesis and characterization of a new fluorescent probe, FFN206, as an excellent VMAT2 substrate capable of detecting VMAT2 activity in intact cells using fluorescence microscopy, with subcellular localization to VMAT2-expressing acidic compartments without apparent labeling of other organelles. VMAT2 activity can also be measured via microplate reader. The apparent Km of FFN206 at VMAT2 was found to be 1.16 ± 0.10 μM, similar to that of dopamine. We further report the development and validation of a cell-based fluorescence assay amenable to high-throughput screening (HTS) using VMAT2-transfected HEK cells (Z'-factor of 0.7-0.8), enabling rapid identification of VMAT2 inhibitors and measurement of their inhibition constants over a broad range of affinities. FFN206 thus represents a new tool for optical examination of VMAT2 function in cell culture.
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Affiliation(s)
- Gang Hu
- Department
of Chemistry, Columbia University, New
York, New York 10027, United
States
| | - Adam Henke
- Department
of Chemistry, Columbia University, New
York, New York 10027, United
States
| | - Richard J. Karpowicz
- Department
of Chemistry, Columbia University, New
York, New York 10027, United
States
| | - Mark S. Sonders
- Departments of Psychiatry and
Neurology, Columbia University, New York,
New York 10032, United States
| | - Frances Farrimond
- Departments of Neurology and
Physiology, University of California School of Medicine, San Francisco, San Francisco, California 94143, United
States
| | - Robert Edwards
- Departments of Neurology and
Physiology, University of California School of Medicine, San Francisco, San Francisco, California 94143, United
States
| | - David Sulzer
- Departments of
Neurology, Psychiatry,
and Pharmacology, Columbia University,
New York, New York 10032, United States
| | - Dalibor Sames
- Department
of Chemistry, Columbia University, New
York, New York 10027, United
States
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Karpowicz RJ, Dunn M, Sulzer D, Sames D. APP+, a fluorescent analogue of the neurotoxin MPP+, is a marker of catecholamine neurons in brain tissue, but not a fluorescent false neurotransmitter. ACS Chem Neurosci 2013; 4:858-69. [PMID: 23647019 PMCID: PMC3656749 DOI: 10.1021/cn400038u] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 04/21/2013] [Indexed: 01/20/2023] Open
Abstract
We have previously introduced fluorescent false neurotransmitters (FFNs) as optical reporters that enable visualization of individual dopaminergic presynaptic terminals and their activity in the brain. In this context, we examined the fluorescent pyridinium dye 4-(4-dimethylamino)phenyl-1-methylpyridinium (APP+), a fluorescent analogue of the dopaminergic neurotoxin MPP+, in acute mouse brain tissue. APP+ is a substrate for the dopamine transporter (DAT), norepinephrine transporter (NET), and serotonin transporter (SERT), and as such represented a candidate for the development of new FFN probes. Here we report that APP+ labels cell bodies of catecholaminergic neurons in the midbrain in a DAT- and NET-dependent manner, as well as fine dopaminergic axonal processes in the dorsal striatum. APP+ destaining from presynaptic terminals in the dorsal striatum was also examined under the conditions inducing depolarization and exocytotic neurotransmitter release. Application of KCl led to a small but significant degree of destaining (approximately 15% compared to control), which stands in contrast to a nearly complete destaining of the new generation FFN agent, FFN102. Electrical stimulation of brain slices at 10 Hz afforded no significant change in the APP+ signal. These results indicate that the majority of the APP+ signal in axonal processes originates from labeled organelles including mitochondria, whereas only a minor component of the APP+ signal represents the releasable synaptic vesicular pool. These results also show that APP+ may serve as a useful probe for identifying catecholaminergic innervations in the brain, although it is a poor candidate for the development of FFNs.
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Affiliation(s)
- Richard J. Karpowicz
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York
10027, United States
| | - Matthew Dunn
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York
10027, United States
| | - David Sulzer
- Departments
of Neurology, Psychiatry and Pharmacology, Columbia University
Medical Center, New York, New York 10032, United States
- Department of Neuroscience, New York Psychiatric Institute, New York, New York
10032, United States
| | - Dalibor Sames
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York
10027, United States
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Koshkin V, Krylov SN. Single-Cell-Kinetics Approach to Discover Functionally Distinct Subpopulations within Phenotypically Uniform Populations of Cells. Anal Chem 2013; 85:2578-81. [DOI: 10.1021/ac400151v] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Vasilij Koshkin
- Department of Chemistry and Centre
for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada
| | - Sergey N. Krylov
- Department of Chemistry and Centre
for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada
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40
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Wilson JN, Brown AS, Babinchak WM, Ridge CD, Walls JD. Fluorescent stilbazolium dyes as probes of the norepinephrine transporter: structural insights into substrate binding. Org Biomol Chem 2012; 10:8710-9. [DOI: 10.1039/c2ob26633d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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