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Li M, Chen Q, Zhang YW. Determining Ligand and Ion-Induced Conformational Changes in Serotonin Transporter with Its Fluorescent Substrates. Int J Mol Sci 2022; 23:10919. [PMID: 36142837 DOI: 10.3390/ijms231810919] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [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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Rayff da Silva P, Diniz Nunes Pazos N, Karla Silva do Nascimento Gonzaga T, Cabral de Andrade J, Brito Monteiro Á, Caroline Ribeiro Portela A, Fernandes Oliveira Pires H, Dos Santos Maia M, Vilar da Fonsêca D, T Scotti M, Maria Barbosa Filho J, Pergentino de Sousa D, Francisco Bezerra Felipe C, Nóbrega de Almeida R, Scotti L. Anxiolytic and antidepressant-like effects of monoterpene tetrahydrolinalool and in silico approach of new potential targets. Curr Top Med Chem 2022; 22:1530-1552. [PMID: 35524664 DOI: 10.2174/1568026622666220505104726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/03/2022] [Accepted: 02/16/2022] [Indexed: 11/22/2022]
Abstract
INTRODUCTION- The drugs currently available for treatment of anxiety and depression act through modulation of the neurotransmission systems involved in the neurobiology of the disorder, yet they of-ten present side effects, which can impair patient adherence to treatment. METHOD- This, has driven the search for new molecules with anxiolytic and antidepressant potential. Aromatic plants are rich in essential oils, and their chemical constituents, such as monoterpenes, are be-ing studied for these disorders. This study aims to evaluate the anxiolytic and antidepressant-like poten-tial of the monoterpene tetrahydrolinalool in in vivo animal models, and review pharmacological targets with validation through molecular docking. Male Swiss mice (Mus musculus) were treated with THL (37.5-600 mg kg-1 p.o.) and submitted to the elevated plus maze, open field, rota rod, and forced swim tests. In the elevated plus-maze, THL at doses of 37.5 and 75 mg kg-1 induced a significant increase in the percentage of entries (72.7 and 64.3% respectively), and lengths of stay (80.3 and 76.8% respective-ly) in the open arms tests. RESULT- These doses did not compromise locomotor activity or motor coordination in the animals. In the open field, rota rod tests, and the forced swimming model, treatment with THL significantly reduced immobility times at doses of 150, 300, and 600 mg kg-1, and by respective percentages of 69.3, 60.9 and 68.7%. CONCLUSION- In molecular docking assay, which investigated potential targets, THL presented sat-isfactory energy values for: nNOs, SGC, IL-6, 5-HT1A, NMDAr, and D1. These demonstrate the po-tential of THL (a derivative of natural origin) in in vivo and in silico models, making it a drug candidate.
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Affiliation(s)
- Pablo Rayff da Silva
- Psychopharmacology Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-085, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
| | - Natalia Diniz Nunes Pazos
- Psychopharmacology Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-085, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
| | | | - Jéssica Cabral de Andrade
- Psychopharmacology Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-085, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
| | - Álefe Brito Monteiro
- Psychopharmacology Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-085, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
| | - Anne Caroline Ribeiro Portela
- Psychopharmacology Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-085, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
| | - Hugo Fernandes Oliveira Pires
- Psychopharmacology Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-085, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
| | - Mayara Dos Santos Maia
- Cheminformatics Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-900, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
| | - Diogo Vilar da Fonsêca
- Collegiate of Medicine, Federal University of São Francisco Valley, 48607-190, Rua Aurora, S/N, Bahia, Brazil
| | - Marcus T Scotti
- Cheminformatics Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-900, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
| | - José Maria Barbosa Filho
- Pharmaceutical Chemistry Laboratory, Department of Pharmaceutical Sciences, Federal University of Paraíba, 58051-900, Via Ipê Amarelo, S/N, João Pessoa, Brazil
| | - Damião Pergentino de Sousa
- Pharmaceutical Chemistry Laboratory, Department of Pharmaceutical Sciences, Federal University of Paraíba, 58051-900, Via Ipê Amarelo, S/N, João Pessoa, Brazil
| | - Cícero Francisco Bezerra Felipe
- Psychopharmacology Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-085, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
| | - Reinaldo Nóbrega de Almeida
- Psychopharmacology Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-085, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
| | - Luciana Scotti
- Cheminformatics Laboratory, Institute of Drugs and Medicines Research, Federal University of Paraíba, 58051-900, Via Ipê Amarelo, S/N, João Pessoa, Paraíba, Brazil
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Xue W, Fu T, Deng S, Yang F, Yang J, Zhu F. Molecular Mechanism for the Allosteric Inhibition of the Human Serotonin Transporter by Antidepressant Escitalopram. ACS Chem Neurosci 2022; 13:340-351. [PMID: 35041375 DOI: 10.1021/acschemneuro.1c00694] [Citation(s) in RCA: 59] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Human serotine transporter (hSERT) is one of the most influential drug targets, and its allosteric modulators (e.g., escitalopram) have emerged to be the next-generation medication for psychiatric disorders. However, the molecular mechanism underlying the allosteric modulation of hSERT is still elusive. Here, the simulation strategies of conventional (cMD) and steered (SMD) molecular dynamics were applied to investigate this molecular mechanism from distinct perspectives. First, cMD simulations revealed that escitalopram's binding to hSERT's allosteric site simultaneously enhanced its binding to the orthosteric site. Then, SMD simulation identified that the occupation of hSERT's allosteric site by escitalopram could also block its dissociation from the orthosteric site. Finally, by comparing the simulated structures of two hSERT-escitalopram complexes with and without allosteric modulation, a new conformational coupling between an extracellular (Arg104-Glu494) and an intracellular (Lys490-Glu494) salt bridge was identified. In summary, this study explored the mechanism underlying the allosteric modulation of hSERT by collectively applying two MD simulation strategies, which could facilitate our understanding of the allosteric modulations of not only hSERT but also other clinically important therapeutic targets.
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Affiliation(s)
- Weiwei Xue
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Innovative Drug Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
- Central Nervous System Drug Key Laboratory of Sichuan Province, Luzhou 646000, China
| | - Tingting Fu
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Innovative Drug Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Shengzhe Deng
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Innovative Drug Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Fengyuan Yang
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Innovative Drug Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Jingyi Yang
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Innovative Drug Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Feng Zhu
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Innovative Drug Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, Alibaba-Zhejiang University Joint Research Center of Future Digital Healthcare, Hangzhou 330110, China
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Gradisch R, Szöllősi D, Niello M, Lazzarin E, Sitte HH, Stockner T. Occlusion of the human serotonin transporter is mediated by serotonin-induced conformational changes in the bundle domain. J Biol Chem 2022; 298:101613. [PMID: 35065961 DOI: 10.1016/j.jbc.2022.101613] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 01/16/2022] [Accepted: 01/17/2022] [Indexed: 12/04/2022] Open
Abstract
The human serotonin transporter (hSERT) terminates neurotransmission by removing serotonin (5HT) from the synaptic cleft, an essential process for proper functioning of serotonergic neurons. Structures of the hSERT have revealed its molecular architecture in four conformations, including the outward-open and occluded states, and show the transporter’s engagement with co-transported ions and the binding mode of inhibitors. In this study, we investigated the molecular mechanism by which the hSERT occludes and sequesters the substrate 5HT. This first step of substrate uptake into cells is a structural change consisting of the transition from the outward-open to the occluded state. Inhibitors such as the antidepressants citalopram, fluoxetine, and sertraline inhibit this step of the transport cycle. Using molecular dynamics simulations, we reached a fully occluded state, in which the transporter-bound 5HT becomes fully shielded from both sides of the membrane by two closed hydrophobic gates. Analysis of 5HT-triggered occlusion showed that bound 5HT serves as an essential trigger for transporter occlusion. Moreover, simulations revealed a complex sequence of steps and showed that movements of bundle domain helices are only partially correlated. 5HT-triggered occlusion is initially dominated by movements of transmembrane helix 1b, while in the final step, only transmembrane helix 6a moves and relaxes an intermediate change in its secondary structure.
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Plenge P, Yang D, Salomon K, Laursen L, Kalenderoglou IE, Newman AH, Gouaux E, Coleman JA, Loland CJ. The antidepressant drug vilazodone is an allosteric inhibitor of the serotonin transporter. Nat Commun 2021; 12:5063. [PMID: 34417466 DOI: 10.1038/s41467-021-25363-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 08/05/2021] [Indexed: 12/12/2022] Open
Abstract
Depression is a common mental disorder. The standard medical treatment is the selective serotonin reuptake inhibitors (SSRIs). All characterized SSRIs are competitive inhibitors of the serotonin transporter (SERT). A non-competitive inhibitor may produce a more favorable therapeutic profile. Vilazodone is an antidepressant with limited information on its molecular interactions with SERT. Here we use molecular pharmacology and cryo-EM structural elucidation to characterize vilazodone binding to SERT. We find that it exhibits non-competitive inhibition of serotonin uptake and impedes dissociation of [3H]imipramine at low nanomolar concentrations. Our SERT structure with bound imipramine and vilazodone reveals a unique binding pocket for vilazodone, expanding the boundaries of the extracellular vestibule. Characterization of the binding site is substantiated with molecular dynamics simulations and systematic mutagenesis of interacting residues resulting in decreased vilazodone binding to the allosteric site. Our findings underline the versatility of SERT allosteric ligands and describe the unique binding characteristics of vilazodone. Vilazodone (VLZ) is a drug for the treatment of major depressive disorders that targets the serotonin transporter (SERT). Here, the authors combine pharmacology measurements and cryo-EM structural analysis to characterize VLZ binding to SERT and observe that VLZ exhibits non-competitive inhibition of serotonin transport and binds with nanomolar affinity to an allosteric site in SERT.
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Eh-Haj BM. Metabolic N-Dealkylation and N-Oxidation as Elucidators of the Role of Alkylamino Moieties in Drugs Acting at Various Receptors. Molecules 2021; 26:1917. [PMID: 33805491 PMCID: PMC8036657 DOI: 10.3390/molecules26071917] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 03/22/2021] [Accepted: 03/24/2021] [Indexed: 12/16/2022] Open
Abstract
Metabolic reactions that occur at alkylamino moieties may provide insight into the roles of these moieties when they are parts of drug molecules that act at different receptors. N-dealkylation of N,N-dialkylamino moieties has been associated with retaining, attenuation or loss of pharmacologic activities of metabolites compared to their parent drugs. Further, N-dealkylation has resulted in clinically used drugs, activation of prodrugs, change of receptor selectivity, and providing potential for developing fully-fledged drugs. While both secondary and tertiary alkylamino moieties (open chain aliphatic or heterocyclic) are metabolized by CYP450 isozymes oxidative N-dealkylation, only tertiary alkylamino moieties are subject to metabolic N-oxidation by Flavin-containing monooxygenase (FMO) to give N-oxide products. In this review, two aspects will be examined after surveying the metabolism of representative alkylamino-moieties-containing drugs that act at various receptors (i) the pharmacologic activities and relevant physicochemical properties (basicity and polarity) of the metabolites with respect to their parent drugs and (ii) the role of alkylamino moieties on the molecular docking of drugs in receptors. Such information is illuminative in structure-based drug design considering that fully-fledged metabolite drugs and metabolite prodrugs have been, respectively, developed from N-desalkyl and N-oxide metabolites.
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Affiliation(s)
- Babiker M Eh-Haj
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, University of Science and Technology of Fujairah, Emirate of Fujairah, Fujairah 2022, United Arab Emirates
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Razavi R, Ahmadi SA. Molecular machine based on Rotaxane@Tricyclic antidepressant carrier: Theoretical molecular dynamic simulation. COMPUT THEOR CHEM 2021; 1197:113138. [DOI: 10.1016/j.comptc.2020.113138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Xue W, Fu T, Zheng G, Tu G, Zhang Y, Yang F, Tao L, Yao L, Zhu F. Recent Advances and Challenges of the Drugs Acting on Monoamine Transporters. Curr Med Chem 2020; 27:3830-3876. [DOI: 10.2174/0929867325666181009123218] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 09/30/2018] [Accepted: 10/03/2018] [Indexed: 01/06/2023]
Abstract
Background:
The human Monoamine Transporters (hMATs), primarily including hSERT,
hNET and hDAT, are important targets for the treatment of depression and other behavioral disorders
with more than the availability of 30 approved drugs.
Objective:
This paper is to review the recent progress in the binding mode and inhibitory mechanism of
hMATs inhibitors with the central or allosteric binding sites, for the benefit of future hMATs inhibitor
design and discovery. The Structure-Activity Relationship (SAR) and the selectivity for hit/lead compounds
to hMATs that are evaluated by in vitro and in vivo experiments will be highlighted.
Methods:
PubMed and Web of Science databases were searched for protein-ligand interaction, novel
inhibitors design and synthesis studies related to hMATs.
Results:
Literature data indicate that since the first crystal structure determinations of the homologous
bacterial Leucine Transporter (LeuT) complexed with clomipramine, a sizable database of over 100 experimental
structures or computational models has been accumulated that now defines a substantial degree
of structural variability hMATs-ligands recognition. In the meanwhile, a number of novel hMATs
inhibitors have been discovered by medicinal chemistry with significant help from computational models.
Conclusion:
The reported new compounds act on hMATs as well as the structures of the transporters
complexed with diverse ligands by either experiment or computational modeling have shed light on the
poly-pharmacology, multimodal and allosteric regulation of the drugs to transporters. All of the studies
will greatly promote the Structure-Based Drug Design (SBDD) of structurally novel scaffolds with high
activity and selectivity for hMATs.
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Affiliation(s)
- Weiwei Xue
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Tingting Fu
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Guoxun Zheng
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Gao Tu
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Yang Zhang
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Fengyuan Yang
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
| | - Lin Tao
- Key Laboratory of Elemene Class Anti-cancer Chinese Medicine of Zhejiang Province, School of Medicine, Hangzhou Normal University, Hangzhou 310036, China
| | - Lixia Yao
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN 55905, United States
| | - Feng Zhu
- Innovative Drug Research and Bioinformatics Group, School of Pharmaceutical Sciences and Chongqing Key Laboratory of Natural Drug Research, Chongqing University, Chongqing 401331, China
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Cheng B, Morstein J, Ladefoged LK, Maesen JB, Schiøtt B, Sinning S, Trauner D. A Photoswitchable Inhibitor of the Human Serotonin Transporter. ACS Chem Neurosci 2020; 11:1231-1237. [PMID: 32275382 DOI: 10.1021/acschemneuro.9b00521] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The human serotonin transporter (hSERT) terminates serotonergic signaling through reuptake of neurotransmitter into presynaptic neurons and is a target for many antidepressant drugs. We describe here the development of a photoswitchable hSERT inhibitor, termed azo-escitalopram, that can be reversibly switched between trans and cis configurations using light of different wavelengths. The dark-adapted trans isomer was found to be significantly less active than the cis isomer, formed upon irradiation.
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Affiliation(s)
- Bichu Cheng
- School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
- Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States
| | - Johannes Morstein
- Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States
| | - Lucy Kate Ladefoged
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Jannick Bang Maesen
- Department of Forensic Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark
| | - Birgit Schiøtt
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Steffen Sinning
- Department of Forensic Medicine, Aarhus University, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark
| | - Dirk Trauner
- Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States
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Kardile RD, Chao T, Cheng M, Liu R. Gold(I)‐Catalyzed Highly Diastereo‐ and Enantioselective Cyclization–[4+3] Annulation Cascades between 2‐(1‐Alkynyl)‐2‐alken‐1‐ones and Anthranils. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202001854] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Rahul Dadabhau Kardile
- Frontier Research Center on Fundamental and Applied Sciences of Matters Department of Chemistry National Tsing-Hua University Hsinchu Taiwan, ROC
| | - Tzu‐Hsuan Chao
- Department of Chemistry National Cheng Kung University East District Tainan City Taiwan, ROC
| | - Mu‐Jeng Cheng
- Department of Chemistry National Cheng Kung University East District Tainan City Taiwan, ROC
| | - Rai‐Shung Liu
- Frontier Research Center on Fundamental and Applied Sciences of Matters Department of Chemistry National Tsing-Hua University Hsinchu Taiwan, ROC
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Kardile RD, Chao T, Cheng M, Liu R. Gold(I)‐Catalyzed Highly Diastereo‐ and Enantioselective Cyclization–[4+3] Annulation Cascades between 2‐(1‐Alkynyl)‐2‐alken‐1‐ones and Anthranils. Angew Chem Int Ed Engl 2020; 59:10396-10400. [DOI: 10.1002/anie.202001854] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Indexed: 11/05/2022]
Affiliation(s)
- Rahul Dadabhau Kardile
- Frontier Research Center on Fundamental and Applied Sciences of Matters Department of Chemistry National Tsing-Hua University Hsinchu Taiwan, ROC
| | - Tzu‐Hsuan Chao
- Department of Chemistry National Cheng Kung University East District Tainan City Taiwan, ROC
| | - Mu‐Jeng Cheng
- Department of Chemistry National Cheng Kung University East District Tainan City Taiwan, ROC
| | - Rai‐Shung Liu
- Frontier Research Center on Fundamental and Applied Sciences of Matters Department of Chemistry National Tsing-Hua University Hsinchu Taiwan, ROC
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12
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Plenge P, Abramyan AM, Sørensen G, Mørk A, Weikop P, Gether U, Bang-Andersen B, Shi L, Loland CJ. The mechanism of a high-affinity allosteric inhibitor of the serotonin transporter. Nat Commun 2020; 11:1491. [PMID: 32198394 DOI: 10.1038/s41467-020-15292-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 02/24/2020] [Indexed: 11/08/2022] Open
Abstract
The serotonin transporter (SERT) terminates serotonin signaling by rapid presynaptic reuptake. SERT activity is modulated by antidepressants, e.g., S-citalopram and imipramine, to alleviate symptoms of depression and anxiety. SERT crystal structures reveal two S-citalopram binding pockets in the central binding (S1) site and the extracellular vestibule (S2 site). In this study, our combined in vitro and in silico analysis indicates that the bound S-citalopram or imipramine in S1 is allosterically coupled to the ligand binding to S2 through altering protein conformations. Remarkably, SERT inhibitor Lu AF60097, the first high-affinity S2-ligand reported and characterized here, allosterically couples the ligand binding to S1 through a similar mechanism. The SERT inhibition by Lu AF60097 is demonstrated by the potentiated imipramine binding and increased hippocampal serotonin level in rats. Together, we reveal a S1-S2 coupling mechanism that will facilitate rational design of high-affinity SERT allosteric inhibitors.
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Hellsberg E, Ecker GF, Stary-Weinzinger A, Forrest LR. A structural model of the human serotonin transporter in an outward-occluded state. PLoS One 2019; 14:e0217377. [PMID: 31251747 PMCID: PMC6599148 DOI: 10.1371/journal.pone.0217377] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 06/17/2019] [Indexed: 12/12/2022] Open
Abstract
The human serotonin transporter hSERT facilitates the reuptake of its endogenous substrate serotonin from the synaptic cleft into presynaptic neurons after signaling. Reuptake regulates the availability of this neurotransmitter and therefore hSERT plays an important role in balancing human mood conditions. In 2016, the first 3D structures of this membrane transporter were reported in an inhibitor-bound, outward-open conformation. These structures revealed valuable information about interactions of hSERT with antidepressant drugs. Nevertheless, the question remains how serotonin facilitates the specific conformational changes that open and close pathways from the synapse and to the cytoplasm as required for transport. Here, we present a serotonin-bound homology model of hSERT in an outward-occluded state, a key intermediate in the physiological cycle, in which the interactions with the substrate are likely to be optimal. Our approach uses two template structures and includes careful refinement and comprehensive computational validation. According to microsecond-long molecular dynamics simulations, this model exhibits interactions between the gating residues in the extracellular pathway, and these interactions differ from those in an outward-open conformation of hSERT bound to serotonin. Moreover, we predict several features of this state by monitoring the intracellular gating residues, the extent of hydration, and, most importantly, protein-ligand interactions in the central binding site. The results illustrate common and distinct characteristics of these two transporter states and provide a starting point for future investigations of the transport mechanism in hSERT.
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Affiliation(s)
- Eva Hellsberg
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Gerhard F. Ecker
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | | | - Lucy R. Forrest
- Computational Structural Biology Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States of America
- * E-mail:
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Blackburn TP. Depressive disorders: Treatment failures and poor prognosis over the last 50 years. Pharmacol Res Perspect 2019; 7:e00472. [PMID: 31065377 PMCID: PMC6498411 DOI: 10.1002/prp2.472] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 02/11/2019] [Accepted: 03/18/2019] [Indexed: 12/12/2022] Open
Abstract
Depression like many diseases is pleiotropic but unlike cancer and Alzheimer's disease for example, is still largely stigmatized and falls into the dark shadows of human illness. The failure of depression to be in the spotlight for successful treatment options is inherent in the complexity of the disease(s), flawed clinical diagnosis, overgeneralization of the illness, inadequate and biased clinical trial design, restrictive and biased inclusion/exclusion criteria, lack of approved/robust biomarkers, expensive imaging technology along with few advances in neurobiological hypotheses in decades. Clinical trial studies summitted to the regulatory agencies (FDA/EMA) for approval, have continually failed to show significant differences between active and placebo. For decades, we have acknowledged this failure, despite vigorous debated by all stakeholders to provide adequate answers to this escalating problem, with only a few new antidepressants approved in the last 20 years with equivocal efficacy, little improvement in side effects or onset of efficacy. It is also clear that funding and initiatives for mental illness lags far behind other life-treating diseases. Thus, it is no surprise we have not achieved much success in the last 50 years in treating depression, but we are accountable for the many failures and suboptimal treatment. This review will therefore critically address where we have failed and how future advances in medical science offers a glimmer of light for the patient and aid our future understanding of the neurobiology and pathophysiology of the disease, enabling transformative therapies for the treatment of depressive disorders.
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15
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Ladefoged LK, Zeppelin T, Schiøtt B. Molecular modeling of neurological membrane proteins − from binding sites to synapses. Neurosci Lett 2019; 700:38-49. [DOI: 10.1016/j.neulet.2018.05.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 05/18/2018] [Accepted: 05/22/2018] [Indexed: 01/07/2023]
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16
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Zeppelin T, Ladefoged LK, Sinning S, Schiøtt B. Substrate and inhibitor binding to the serotonin transporter: Insights from computational, crystallographic, and functional studies. Neuropharmacology 2019; 161:107548. [PMID: 30807752 DOI: 10.1016/j.neuropharm.2019.02.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/19/2019] [Accepted: 02/22/2019] [Indexed: 02/02/2023]
Abstract
The serotonin transporter (SERT) belongs to the monoamine transporter family, which also includes the dopamine and norepinephrine transporters. SERT is essential for regulating serotonergic signaling by the reuptake of serotonin from the synaptic cleft back into the presynaptic neuron. Dysregulation of SERT has been implicated in several major psychiatric disorders such as major depressive disorder (MDD). MDD was among the top five leading causes of years lived with disease in 2016 and is characterized as a major global burden. Several drugs have been developed to target SERT for use in the treatment of MDD, and their respective binding modes and locations within SERT have been studied. The elucidation of the first structure of a bacterial SERT homologue in 2005 has accelerated crystallographic, computational, and functional studies to further elucidate drug binding and method of action in SERT. Herein, we aim to highlight and compare these studies with an emphasis on what the different experimental methods conclude on substrate and inhibitor binding modes, and the potential caveats of using the different types of studies are discussed. We focus this review on the binding of cognate substrate and drugs belonging to the different families of antidepressants, including tricyclic antidepressants, selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and multimodal drugs, as well as illicit drugs such as cocaine, amphetamines, and ibogaine. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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17
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Yarravarapu N, Geffert L, Surratt CK, Cascio M, Lapinsky DJ. Clickable photoaffinity ligands for the human serotonin transporter based on the selective serotonin reuptake inhibitor (S)-citalopram. Bioorg Med Chem Lett 2018; 28:3431-3435. [PMID: 30266542 DOI: 10.1016/j.bmcl.2018.09.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/20/2018] [Accepted: 09/22/2018] [Indexed: 12/16/2022]
Abstract
To date, the development of photoaffinity ligands targeting the human serotonin transporter (hSERT), a key protein involved in disease states such as depression and anxiety, have been radioisotope-based (i.e., 3H or 125I). This letter instead highlights three derivatives of the selective serotonin reuptake inhibitor (SSRI) (S)-citalopram that were rationally designed and synthesized to contain a photoreactive benzophenone or an aryl azide for protein target capture via photoaffinity labeling and a terminal alkyne or an aliphatic azide for click chemistry-based proteomics. Specifically, clickable benzophenone-based (S)-citalopram photoprobe 6 (hSERT Ki = 0.16 nM) displayed 11-fold higher binding affinity at hSERT when compared to (S)-citalopram (hSERT Ki = 1.77 nM), and was subsequently shown to successfully undergo tandem photoaffinity labeling-biorthogonal conjugation using purified hSERT. Given clickable photoprobes can be used for various applications depending on which reporter is attached by click chemistry subsequent to photoaffinity labeling, photoprobe 6 is expected to find value in structure-function studies and other research applications involving hSERT (e.g., imaging).
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Affiliation(s)
- Nageswari Yarravarapu
- Graduate School of Pharmaceutical Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282, United States
| | - Laura Geffert
- Graduate School of Pharmaceutical Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282, United States
| | - Christopher K Surratt
- Graduate School of Pharmaceutical Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282, United States
| | - Michael Cascio
- Bayer School of Natural and Environmental Sciences, Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282, United States
| | - David J Lapinsky
- Graduate School of Pharmaceutical Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282, United States.
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18
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Laursen L, Severinsen K, Kristensen KB, Periole X, Overby M, Müller HK, Schiøtt B, Sinning S. Cholesterol binding to a conserved site modulates the conformation, pharmacology, and transport kinetics of the human serotonin transporter. J Biol Chem 2018; 293:3510-3523. [PMID: 29352106 DOI: 10.1074/jbc.m117.809046] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 01/14/2018] [Indexed: 12/31/2022] Open
Abstract
The serotonin transporter (SERT) is important for reuptake of the neurotransmitter serotonin from the synaptic cleft and is also the target of most antidepressants. It has previously been shown that cholesterol in the membrane bilayer affects the conformation of SERT. Although recent crystal structures have identified several potential cholesterol-binding sites, it is unclear whether any of these potential cholesterol sites are occupied by cholesterol and functionally relevant. In the present study, we focus on the conserved cholesterol site 1 (CHOL1) located in a hydrophobic groove between TM1a, TM5, and TM7. By molecular dynamics simulations, we demonstrate a strong binding of cholesterol to CHOL1 in a membrane bilayer environment. In biochemical experiments, we find that cholesterol depletion induces a more inward-facing conformation favoring substrate analog binding. Consistent with this, we find that mutations in CHOL1 with a negative impact on cholesterol binding induce a more inward-facing conformation, and, vice versa, mutations with a positive impact on cholesterol binding induce a more outward-facing conformation. This shift in transporter conformation dictated by the ability to bind cholesterol in CHOL1 affects the apparent substrate affinity, maximum transport velocity, and turnover rates. Taken together, we show that occupation of CHOL1 by cholesterol is of major importance in the transporter conformational equilibrium, which in turn dictates ligand potency and serotonin transport activity. Based on our findings, we propose a mechanistic model that incorporates the role of cholesterol binding to CHOL1 in the function of SERT.
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Affiliation(s)
- Louise Laursen
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| | - Kasper Severinsen
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| | - Kristina Birch Kristensen
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| | - Xavier Periole
- the Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Malene Overby
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| | - Heidi Kaastrup Müller
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
| | - Birgit Schiøtt
- the Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Steffen Sinning
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark and
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19
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Abstract
The number of ligand binding sites in neurotransmitter-sodium symporters has been determined by crystal structure analysis and molecular pharmacology with controversial results. Here, we designed molecular tools to measure the interaction forces between the serotonin transporter (SERT) and S-citalopram on the single-molecule level by means of atomic force microscopy. Force spectroscopy allows for the extraction of dynamic information under physiological conditions which is inaccessible via X-ray crystallography. Two populations of distinctly different binding strength between S-citalopram and SERT were demonstrated in Na+-containing buffer. In Li+-containing buffer, SERT showed merely low-force interactions, whereas the vestibular mutant SERT-G402H only displayed the high force population. These observations provide physical evidence for the existence of two different binding sites in SERT when tested under near-physiological conditions.
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Affiliation(s)
- Rong Zhu
- Institute of Biophysics, Johannes Kepler University Linz, Linz, Austria
| | - Hermann J Gruber
- Institute of Biophysics, Johannes Kepler University Linz, Linz, Austria
| | - Peter Hinterdorfer
- Institute of Biophysics, Johannes Kepler University Linz, Linz, Austria.
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20
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Erol I, Aksoydan B, Kantarcioglu I, Salmas RE, Durdagi S. Identification of novel serotonin reuptake inhibitors targeting central and allosteric binding sites: A virtual screening and molecular dynamics simulations study. J Mol Graph Model 2017; 74:193-202. [DOI: 10.1016/j.jmgm.2017.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/26/2017] [Accepted: 02/02/2017] [Indexed: 10/19/2022]
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21
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Ferraro M, Masetti M, Recanatini M, Cavalli A, Bottegoni G. Mapping Cholesterol Interaction Sites on Serotonin Transporter through Coarse-Grained Molecular Dynamics. PLoS One 2016; 11:e0166196. [PMID: 27907003 PMCID: PMC5132266 DOI: 10.1371/journal.pone.0166196] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 10/24/2016] [Indexed: 12/19/2022] Open
Abstract
Serotonin transporter (SERT) modulates serotonergic signaling via re-uptake of serotonin in pre-synaptic cells. The inclusion in cholesterol-enriched membrane domains is crucial for SERT activity, suggesting a cross-talk between the protein and the sterol. Here, we develop a protocol to identify potential cholesterol interaction sites coupling statistical analysis to multi-microsecond coarse-grained molecular dynamics simulations of SERT in a previously validated raft-like membrane model. Six putative sites were found, including a putative CRAC motif on TM4 and a CARC motif on TM10. Among them, four hot-spots near regions related to ion binding, transport, and inhibition were detected. Our results encourage prospective studies to unravel mechanistic features of the transporter and related drug discovery implications.
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Affiliation(s)
| | - Matteo Masetti
- Department of Pharmacy and Biotechnology (FaBiT), Alma Mater Studiorum - Università di Bologna, Bologna, Italy
- * E-mail: (MM); (GB)
| | - Maurizio Recanatini
- Department of Pharmacy and Biotechnology (FaBiT), Alma Mater Studiorum - Università di Bologna, Bologna, Italy
| | - Andrea Cavalli
- CompuNet, Istituto Italiano di Tecnologia, Genova, Italy
- Department of Pharmacy and Biotechnology (FaBiT), Alma Mater Studiorum - Università di Bologna, Bologna, Italy
| | - Giovanni Bottegoni
- CompuNet, Istituto Italiano di Tecnologia, Genova, Italy
- BiKi Technologies s.r.l., Genova, Italy
- * E-mail: (MM); (GB)
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22
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Talbot JN, Geffert LM, Jorvig JE, Goldstein RI, Nielsen CL, Wolters NE, Amos ME, Munro CA, Dallman E, Mereu M, Tanda G, Katz JL, Indarte M, Madura JD, Choi H, Leak RK, Surratt CK. Rapid and sustained antidepressant properties of an NMDA antagonist/monoamine reuptake inhibitor identified via transporter-based virtual screening. Pharmacol Biochem Behav 2016; 150-151:22-30. [DOI: 10.1016/j.pbb.2016.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 08/23/2016] [Accepted: 08/24/2016] [Indexed: 01/08/2023]
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23
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Andersen J, Ladefoged LK, Kristensen TNB, Munro L, Grouleff J, Stuhr-Hansen N, Kristensen AS, Schiøtt B, Strømgaard K. Interrogating the Molecular Basis for Substrate Recognition in Serotonin and Dopamine Transporters with High-Affinity Substrate-Based Bivalent Ligands. ACS Chem Neurosci 2016; 7:1406-1417. [PMID: 27425420 DOI: 10.1021/acschemneuro.6b00164] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The transporters for the neurotransmitters serotonin and dopamine (SERT and DAT, respectively) are targets for drugs used in the treatment of mental disorders and widely used drugs of abuse. Studies of prokaryotic homologues have advanced our structural understanding of SERT and DAT, but it still remains enigmatic whether the human transporters contain one or two high-affinity substrate binding sites. We have designed and employed 24 bivalent ligands possessing a highly systematic combination of substrate moieties (serotonin and/or dopamine) and aliphatic or poly(ethylene glycol) spacers to reveal insight into substrate recognition in SERT and DAT. An optimized bivalent ligand comprising two serotonin moieties binds SERT with 3,800-fold increased affinity compared to that of serotonin, suggesting that the human transporters have two distinct substrate binding sites. We show that the bivalent ligands are inhibitors of SERT and an experimentally validated docking model suggests that the bivalent compounds bind with one substrate moiety in the central binding site (the S1 site), whereas the other substrate moiety binds in a distinct binding site (the S2 site). A systematic study of nonconserved SERT/DAT residues surrounding the proposed binding region showed that nonconserved binding site residues do not contribute to selective recognition of substrates in SERT or DAT. This study provides novel insight into the molecular basis for substrate recognition in human transporters and provides an improved foundation for the development of new drugs targeting SERT and DAT.
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Affiliation(s)
- Jacob Andersen
- Department
of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Lucy Kate Ladefoged
- Interdisciplinary
Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Trine N. Bjerre Kristensen
- Interdisciplinary
Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Lachlan Munro
- Department
of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Julie Grouleff
- Interdisciplinary
Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Nicolai Stuhr-Hansen
- Department
of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Anders S. Kristensen
- Department
of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Birgit Schiøtt
- Interdisciplinary
Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Kristian Strømgaard
- Department
of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen, Denmark
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24
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Zheng G, Xue W, Wang P, Yang F, Li B, Li X, Li Y, Yao X, Zhu F. Exploring the Inhibitory Mechanism of Approved Selective Norepinephrine Reuptake Inhibitors and Reboxetine Enantiomers by Molecular Dynamics Study. Sci Rep 2016; 6:26883. [PMID: 27230580 PMCID: PMC4882549 DOI: 10.1038/srep26883] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 05/09/2016] [Indexed: 12/28/2022] Open
Abstract
Selective norepinephrine reuptake inhibitors (sNRIs) provide an effective class of approved antipsychotics, whose inhibitory mechanism could facilitate the discovery of privileged scaffolds with enhanced drug efficacy. However, the crystal structure of human norepinephrine transporter (hNET) has not been determined yet and the inhibitory mechanism of sNRIs remains elusive. In this work, multiple computational methods were integrated to explore the inhibitory mechanism of approved sNRIs (atomoxetine, maprotiline, reboxetine and viloxazine), and 3 lines of evidences were provided to verify the calculation results. Consequently, a binding mode defined by interactions between three chemical moieties in sNRIs and eleven residues in hNET was identified as shared by approved sNRIs. In the meantime, binding modes of reboxetine's enantiomers with hNET were compared. 6 key residues favoring the binding of (S, S)-reboxetine over that of (R, R)-reboxetine were discovered. This is the first study reporting that those 11 residues are the common determinants for the binding of approved sNRIs. The identified binding mode shed light on the inhibitory mechanism of approved sNRIs, which could help identify novel scaffolds with improved drug efficacy.
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Affiliation(s)
- Guoxun Zheng
- Innovative Drug Research and Bioinformatics Group, Innovative Drug Research Centre and School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Weiwei Xue
- Innovative Drug Research and Bioinformatics Group, Innovative Drug Research Centre and School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Panpan Wang
- Innovative Drug Research and Bioinformatics Group, Innovative Drug Research Centre and School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Fengyuan Yang
- Innovative Drug Research and Bioinformatics Group, Innovative Drug Research Centre and School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Bo Li
- Innovative Drug Research and Bioinformatics Group, Innovative Drug Research Centre and School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Xiaofeng Li
- Innovative Drug Research and Bioinformatics Group, Innovative Drug Research Centre and School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Yinghong Li
- Innovative Drug Research and Bioinformatics Group, Innovative Drug Research Centre and School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
| | - Xiaojun Yao
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Feng Zhu
- Innovative Drug Research and Bioinformatics Group, Innovative Drug Research Centre and School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China
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25
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Malinauskaite L, Said S, Sahin C, Grouleff J, Shahsavar A, Bjerregaard H, Noer P, Severinsen K, Boesen T, Schiøtt B, Sinning S, Nissen P. A conserved leucine occupies the empty substrate site of LeuT in the Na(+)-free return state. Nat Commun 2016; 7:11673. [PMID: 27221344 PMCID: PMC4894957 DOI: 10.1038/ncomms11673] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 04/18/2016] [Indexed: 02/05/2023] Open
Abstract
Bacterial members of the neurotransmitter:sodium symporter (NSS) family perform Na(+)-dependent amino-acid uptake and extrude H(+) in return. Previous NSS structures represent intermediates of Na(+)/substrate binding or intracellular release, but not the inward-to-outward return transition. Here we report crystal structures of Aquifex aeolicus LeuT in an outward-oriented, Na(+)- and substrate-free state likely to be H(+)-occluded. We find a remarkable rotation of the conserved Leu25 into the empty substrate-binding pocket and rearrangements of the empty Na(+) sites. Mutational studies of the equivalent Leu99 in the human serotonin transporter show a critical role of this residue on the transport rate. Molecular dynamics simulations show that extracellular Na(+) is blocked unless Leu25 is rotated out of the substrate-binding pocket. We propose that Leu25 facilitates the inward-to-outward transition by compensating a Na(+)- and substrate-free state and acts as the gatekeeper for Na(+) binding that prevents leak in inward-outward return transitions.
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Affiliation(s)
- Lina Malinauskaite
- Danish Research Institute of Translational Neuroscience-DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, Aarhus C DK-8000, Denmark
| | - Saida Said
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Skovagervej 2, Risskov DK-8240, Denmark
| | - Caglanur Sahin
- Danish Research Institute of Translational Neuroscience-DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, Aarhus C DK-8000, Denmark
| | - Julie Grouleff
- inSPIN and iNANO centers, Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus C DK-8000, Denmark
| | - Azadeh Shahsavar
- Danish Research Institute of Translational Neuroscience-DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, Aarhus C DK-8000, Denmark
| | - Henriette Bjerregaard
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Skovagervej 2, Risskov DK-8240, Denmark
| | - Pernille Noer
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Skovagervej 2, Risskov DK-8240, Denmark
| | - Kasper Severinsen
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Skovagervej 2, Risskov DK-8240, Denmark
| | - Thomas Boesen
- Danish Research Institute of Translational Neuroscience-DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, Aarhus C DK-8000, Denmark
| | - Birgit Schiøtt
- inSPIN and iNANO centers, Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus C DK-8000, Denmark
| | - Steffen Sinning
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Skovagervej 2, Risskov DK-8240, Denmark
| | - Poul Nissen
- Danish Research Institute of Translational Neuroscience-DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, Aarhus C DK-8000, Denmark
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26
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Grouleff J, Søndergaard S, Koldsø H, Schiøtt B. Properties of an inward-facing state of LeuT: conformational stability and substrate release. Biophys J 2016; 108:1390-1399. [PMID: 25809252 DOI: 10.1016/j.bpj.2015.02.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 01/12/2023] Open
Abstract
The leucine transporter (LeuT) is a bacterial homolog of the human monoamine transporters, which are important pharmaceutical targets. There are no high-resolution structures of the human transporters available; however, LeuT has been crystallized in several different conformational states. Recently, an inward-facing conformation of LeuT was solved revealing an unexpectedly large movement of transmembrane helix 1a (TM1a). We have performed molecular dynamics simulations of the mutated and wild-type transporter, with and without the cocrystallized Fab antibody fragment, to investigate the properties of this inward-facing conformation in relation to transport by LeuT within the membrane environment. In all of the simulations, local conformational changes with respect to the crystal structure are consistently observed, especially in TM1a. Umbrella sampling revealed a soft potential for TM1a tilting. Furthermore, simulations of inward-facing LeuT with Na(+) ions and substrate bound suggest that one of the Na(+) ion binding sites is fully disrupted. Release of alanine and the second Na(+) ion is also observed, giving insight into the final stage of the translocation process in atomistic detail.
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Affiliation(s)
- Julie Grouleff
- Center for Insoluble Protein Structures and Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - Siri Søndergaard
- Center for Insoluble Protein Structures and Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - Heidi Koldsø
- Center for Insoluble Protein Structures and Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - Birgit Schiøtt
- Center for Insoluble Protein Structures and Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University, Aarhus, Denmark.
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27
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Brinkø A, Larsen MT, Koldsø H, Besenbacher L, Kolind A, Schiøtt B, Sinning S, Jensen HH. Synthesis and inhibitory evaluation of 3-linked imipramines for the exploration of the S2 site of the human serotonin transporter. Bioorg Med Chem 2016; 24:2725-38. [PMID: 27160055 DOI: 10.1016/j.bmc.2016.04.039] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 04/16/2016] [Accepted: 04/20/2016] [Indexed: 01/10/2023]
Abstract
The human serotonin transporter is the primary target of several antidepressant drugs, and the importance of a primary, high affinity binding site (S1) for antidepressant binding is well documented. The existence of a lower affinity, secondary binding site (S2) has, however, been debated. Herein we report the synthesis of 3-position coupled imipramine ligands from clomipramine using a copper free Sonogashira reaction. Ligand design was inspired by results from docking and steered molecular dynamics simulations, and the ligands were utilized in a structure-activity relationship study of the positional relationship between the S1 and S2 sites. The computer simulations suggested that the S2 site does indeed exist although with lower affinity for imipramine than observed within the S1 site. Additionally, it was possible to dock the 3-linked imipramine analogs into positions which occupy the S1 and the S2 site simultaneously. The structure activity relationship study showed that the shortest ligands were the most potent, and mutations enlarging the proposed S2 site were found to affect the larger ligands positively, while the smaller ligands were mostly unaffected.
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Rannversson H, Andersen J, Sørensen L, Bang-Andersen B, Park M, Huber T, Sakmar TP, Strømgaard K. Genetically encoded photocrosslinkers locate the high-affinity binding site of antidepressant drugs in the human serotonin transporter. Nat Commun 2016; 7:11261. [PMID: 27089947 DOI: 10.1038/ncomms11261] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 03/07/2016] [Indexed: 02/02/2023] Open
Abstract
Despite the well-established role of the human serotonin transporter (hSERT) in the treatment of depression, the molecular details of antidepressant drug binding are still not fully understood. Here we utilize amber codon suppression in a membrane-bound transporter protein to encode photocrosslinking unnatural amino acids (UAAs) into 75 different positions in hSERT. UAAs are incorporated with high specificity, and functionally active transporters have similar transport properties and pharmacological profiles compared with wild-type transporters. We employ ultraviolet-induced crosslinking with p-azido-L-phenylalanine (azF) at selected positions in hSERT to map the binding site of imipramine, a prototypical tricyclic antidepressant, and vortioxetine, a novel multimodal antidepressant. We find that the two antidepressants crosslink with azF incorporated at different positions within the central substrate-binding site of hSERT, while no crosslinking is observed at the vestibular-binding site. Taken together, our data provide direct evidence for defining the high-affinity antidepressant binding site in hSERT. Molecular details of how antidepressant drugs bind to the human serotonin transporter are not currently clear. Here, the authors introduce photo-cross-linkers into the protein and map the binding site of several antidepressants.
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29
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Davis BA, Nagarajan A, Forrest LR, Singh SK. Mechanism of Paroxetine (Paxil) Inhibition of the Serotonin Transporter. Sci Rep 2016; 6:23789. [PMID: 27032980 PMCID: PMC4817154 DOI: 10.1038/srep23789] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 03/15/2016] [Indexed: 11/11/2022] Open
Abstract
The serotonin transporter (SERT) is an integral membrane protein that exploits preexisting sodium-, chloride-, and potassium ion gradients to catalyze the thermodynamically unfavorable movement of synaptic serotonin into the presynaptic neuron. SERT has garnered significant clinical attention partly because it is the target of multiple psychoactive agents, including the antidepressant paroxetine (Paxil), the most potent selective serotonin reuptake inhibitor known. However, the binding site and orientation of paroxetine in SERT remain controversial. To provide molecular insight, we constructed SERT homology models based on the Drosophila melanogaster dopamine transporter and docked paroxetine to these models. We tested the predicted binding configurations with a combination of radioligand binding and flux assays on wild-type and mutant SERTs. Our data suggest that the orientation of paroxetine, specifically its fluorophenyl ring, in SERT’s substrate binding site directly depends on this pocket’s charge distribution, and thereby provide an avenue toward understanding and enhancing high-affinity antidepressant activity.
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Affiliation(s)
- Bruce A Davis
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520 USA
| | - Anu Nagarajan
- Computational Structural Biology Section, National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Bethesda, MD 20892 USA
| | - Lucy R Forrest
- Computational Structural Biology Section, National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Bethesda, MD 20892 USA
| | - Satinder K Singh
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520 USA
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Kirmeier T, Gopalakrishnan R, Gormanns V, Werner AM, Cuboni S, Rudolf GC, Höfner G, Wanner KT, Sieber SA, Schmidt U, Holsboer F, Rein T, Hausch F. Azidobupramine, an Antidepressant-Derived Bifunctional Neurotransmitter Transporter Ligand Allowing Covalent Labeling and Attachment of Fluorophores. PLoS One 2016; 11:e0148608. [PMID: 26863431 PMCID: PMC4749225 DOI: 10.1371/journal.pone.0148608] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 01/20/2016] [Indexed: 12/21/2022] Open
Abstract
The aim of this study was to design, synthesize and validate a multifunctional antidepressant probe that is modified at two distinct positions. The purpose of these modifications was to allow covalent linkage of the probe to interaction partners, and decoration of probe-target complexes with fluorescent reporter molecules. The strategy for the design of such a probe (i.e., azidobupramine) was guided by the need for the introduction of additional functional groups, conveying the required properties while keeping the additional moieties as small as possible. This should minimize the risk of changing antidepressant-like properties of the new probe azidobupramine. To control for this, we evaluated the binding parameters of azidobupramine to known target sites such as the transporters for serotonin (SERT), norepinephrine (NET), and dopamine (DAT). The binding affinities of azidobupramine to SERT, NET, and DAT were in the range of structurally related and clinically active antidepressants. Furthermore, we successfully visualized azidobupramine-SERT complexes not only in SERT-enriched protein material but also in living cells stably overexpressing SERT. To our knowledge, azidobupramine is the first structural analogue of a tricyclic antidepressant that can be covalently linked to target structures and further attached to reporter molecules while preserving antidepressant-like properties and avoiding radioactive isotopes.
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Affiliation(s)
- Thomas Kirmeier
- Max Planck Institute of Psychiatry, Clinical Department, Munich, Germany
| | - Ranganath Gopalakrishnan
- Max Planck Institute of Psychiatry, Department of Translational Research in Psychiatry, Munich, Germany
| | - Vanessa Gormanns
- Max Planck Institute of Psychiatry, Department of Translational Research in Psychiatry, Munich, Germany
| | - Anna M. Werner
- Max Planck Institute of Psychiatry, Department of Translational Research in Psychiatry, Munich, Germany
| | - Serena Cuboni
- Max Planck Institute of Psychiatry, Department of Translational Research in Psychiatry, Munich, Germany
| | - Georg C. Rudolf
- Technical University Munich, IAS, CIPSM, Department of Chemistry, Garching, Germany
| | - Georg Höfner
- Department Pharmazie Zentrum für Pharmaforschung, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Klaus T. Wanner
- Department Pharmazie Zentrum für Pharmaforschung, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stephan A. Sieber
- Technical University Munich, IAS, CIPSM, Department of Chemistry, Garching, Germany
| | - Ulrike Schmidt
- Max Planck Institute of Psychiatry, Department of Translational Research in Psychiatry, Munich, Germany
| | - Florian Holsboer
- Max Planck Institute of Psychiatry, Clinical Department, Munich, Germany
| | - Theo Rein
- Max Planck Institute of Psychiatry, Department of Translational Research in Psychiatry, Munich, Germany
- * E-mail: (TR); (F. Hausch)
| | - Felix Hausch
- Max Planck Institute of Psychiatry, Department of Translational Research in Psychiatry, Munich, Germany
- * E-mail: (TR); (F. Hausch)
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Larsen MAB, Plenge P, Andersen J, Eildal JNN, Kristensen AS, Bøgesø KP, Gether U, Strømgaard K, Bang-Andersen B, Loland CJ. Structure-activity relationship studies of citalopram derivatives: examining substituents conferring selectivity for the allosteric site in the 5-HT transporter. Br J Pharmacol 2016; 173:925-36. [PMID: 26699847 DOI: 10.1111/bph.13411] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 12/10/2015] [Accepted: 12/14/2015] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND AND PURPOSE The 5-HT transporter (SERT) is a target for antidepressant drugs. SERT possesses two binding sites: the orthosteric (S1) binding site, which is the presumed target for current SERT inhibitors, and an allosteric (S2) site for which potential therapeutic effects are unknown. The antidepressant drug citalopram displays high-affinity S1 binding and low-affinity S2 binding. To elucidate a possible therapeutic role of allosteric inhibition of SERT, a drug that specifically targets the allosteric site is required. The purpose of this study was to find a compound having higher selectivity towards the S2 site. EXPERIMENTAL APPROACH We performed a systematic structure-activity relationship study based on the scaffold of citalopram and the structurally closely related congener, talopram, which shows low-affinity S1 binding in SERT. The role of the four chemical substituents, which distinguish citalopram from talopram in conferring selectivity towards the S1 and S2 site, respectively, was assessed by determining the binding of 14 citalopram/talopram analogous to the S1 and S2 binding sites in SERT using membranes of COS7 cells transiently expressing SERT. KEY RESULTS The structure-activity relationship study revealed that dimethyl citalopram possesses the highest affinity for the allosteric site relative to the S1 site in SERT and has approximately twofold selectivity for the allosteric site relative to the S1 site in SERT. CONCLUSIONS AND IMPLICATIONS The compound could be a useful lead for future synthesis of drugs with high affinity and high selectivity towards the allosteric binding site.
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Affiliation(s)
- M Andreas B Larsen
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Per Plenge
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacob Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonas N N Eildal
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anders S Kristensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Klaus P Bøgesø
- Neuroscience Drug Discovery, H. Lundbeck A/S, Valby, Denmark
| | - Ulrik Gether
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Strømgaard
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Benny Bang-Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Neuroscience Drug Discovery, H. Lundbeck A/S, Valby, Denmark
| | - Claus J Loland
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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32
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Xue W, Wang P, Li B, Li Y, Xu X, Yang F, Yao X, Chen YZ, Xu F, Zhu F. Identification of the inhibitory mechanism of FDA approved selective serotonin reuptake inhibitors: an insight from molecular dynamics simulation study. Phys Chem Chem Phys 2016; 18:3260-71. [DOI: 10.1039/c5cp05771j] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The binding mode shared by 4 FDA approved SSRIs treating major depression was identified by integrating multiple computational methods.
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33
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Raja M, Puntheeranurak T, Gruber HJ, Hinterdorfer P, Kinne RKH. The role of transporter ectodomains in drug recognition and binding: phlorizin and the sodium–glucose cotransporter. Med Chem Commun 2016. [DOI: 10.1039/c5md00572h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This article reviews the role of segments of SLCs located outside the plasma membrane bilayer (ectodomains) using the inhibition of SGLTs (SLC5 family) by the aromatic glucoside phlorizin as a model system.
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Affiliation(s)
- M. Raja
- Max Planck Institute of Molecular Physiology
- Dortmund
- Germany
| | - T. Puntheeranurak
- Department of Biology
- Center of Nanoscience
- Faculty of Science
- Mahidol University
- Bangkok
| | - H. J. Gruber
- Institute for Biophysics
- Christian Doppler Laboratory of Nanoscopic Methods in Biophysics
- Johannes Kepler University of Linz and Center for Advanced Bioanalysis GmbH (CBL)
- Linz
- Austria
| | - P. Hinterdorfer
- Institute for Biophysics
- Christian Doppler Laboratory of Nanoscopic Methods in Biophysics
- Johannes Kepler University of Linz and Center for Advanced Bioanalysis GmbH (CBL)
- Linz
- Austria
| | - R. K. H. Kinne
- Max Planck Institute of Molecular Physiology
- Dortmund
- Germany
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34
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Zhu R, Sinwel D, Hasenhuetl PS, Saha K, Kumar V, Zhang P, Rankl C, Holy M, Sucic S, Kudlacek O, Karner A, Sandtner W, Stockner T, Gruber HJ, Freissmuth M, Newman A, Sitte HH, Hinterdorfer P. Nanopharmacological Force Sensing to Reveal Allosteric Coupling in Transporter Binding Sites. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201508755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Rong Zhu
- Institute for Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
| | - Doris Sinwel
- Institute for Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
- Christian Doppler Laboratory for Nanoscopic Methods in Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
| | - Peter S. Hasenhuetl
- Center of Physiology and Pharmacology; Medical University of Vienna; Waehringerstrasse 13a 1090 Vienna Austria
| | - Kusumika Saha
- Center of Physiology and Pharmacology; Medical University of Vienna; Waehringerstrasse 13a 1090 Vienna Austria
| | - Vivek Kumar
- Medicinal Chemistry Section; Molecular Targets and Medications Discovery Branch; Intramural Research Program; National Institute on Drug Abuse; Baltimore MD 21224 USA
| | - Peng Zhang
- Medicinal Chemistry Section; Molecular Targets and Medications Discovery Branch; Intramural Research Program; National Institute on Drug Abuse; Baltimore MD 21224 USA
| | - Christian Rankl
- Keysight Technologies Austria GmbH; Mooslackengasse 17 1190 Vienna Austria
| | - Marion Holy
- Center of Physiology and Pharmacology; Medical University of Vienna; Waehringerstrasse 13a 1090 Vienna Austria
| | - Sonja Sucic
- Center of Physiology and Pharmacology; Medical University of Vienna; Waehringerstrasse 13a 1090 Vienna Austria
| | - Oliver Kudlacek
- Center of Physiology and Pharmacology; Medical University of Vienna; Waehringerstrasse 13a 1090 Vienna Austria
| | - Andreas Karner
- Institute for Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
- Center for Advanced Bioanalysis; Gruberstrasse 40 4020 Linz Austria
| | - Walter Sandtner
- Center of Physiology and Pharmacology; Medical University of Vienna; Waehringerstrasse 13a 1090 Vienna Austria
| | - Thomas Stockner
- Center of Physiology and Pharmacology; Medical University of Vienna; Waehringerstrasse 13a 1090 Vienna Austria
| | - Hermann J. Gruber
- Institute for Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
| | - Michael Freissmuth
- Center of Physiology and Pharmacology; Medical University of Vienna; Waehringerstrasse 13a 1090 Vienna Austria
| | - Amy Hauck Newman
- Medicinal Chemistry Section; Molecular Targets and Medications Discovery Branch; Intramural Research Program; National Institute on Drug Abuse; Baltimore MD 21224 USA
| | - Harald H. Sitte
- Center of Physiology and Pharmacology; Medical University of Vienna; Waehringerstrasse 13a 1090 Vienna Austria
| | - Peter Hinterdorfer
- Institute for Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
- Christian Doppler Laboratory for Nanoscopic Methods in Biophysics; Johannes Kepler University Linz; Gruberstrasse 40 4020 Linz Austria
- Center for Advanced Bioanalysis; Gruberstrasse 40 4020 Linz Austria
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35
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Zhu R, Sinwel D, Hasenhuetl PS, Saha K, Kumar V, Zhang P, Rankl C, Holy M, Sucic S, Kudlacek O, Karner A, Sandtner W, Stockner T, Gruber HJ, Freissmuth M, Newman AH, Sitte HH, Hinterdorfer P. Nanopharmacological Force Sensing to Reveal Allosteric Coupling in Transporter Binding Sites. Angew Chem Int Ed Engl 2015; 55:1719-22. [PMID: 26695726 DOI: 10.1002/anie.201508755] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 11/11/2015] [Indexed: 11/11/2022]
Abstract
Controversy regarding the number and function of ligand binding sites in neurotransmitter/sodium symporters arose from conflicting data in crystal structures and molecular pharmacology. Here, we have designed novel tools for atomic force microscopy that directly measure the interaction forces between the serotonin transporter (SERT) and the S- and R-enantiomers of citalopram on the single molecule level. This approach is based on force spectroscopy, which allows for the extraction of dynamic information under physiological conditions thus inaccessible via X-ray crystallography. Two distinct populations of characteristic binding strengths of citalopram to SERT were revealed in Na(+)-containing buffer. In contrast, in Li(+) -containing buffer, SERT showed only low force interactions. Conversely, the vestibular mutant SERT-G402H merely displayed the high force population. These observations provide physical evidence for the existence of two binding sites in SERT when accessed in a physiological context. Competition experiments revealed that these two sites are allosterically coupled and exert reciprocal modulation.
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Affiliation(s)
- Rong Zhu
- Institute for Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Doris Sinwel
- Institute for Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria.,Christian Doppler Laboratory for Nanoscopic Methods in Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Peter S Hasenhuetl
- Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090, Vienna, Austria
| | - Kusumika Saha
- Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090, Vienna, Austria
| | - Vivek Kumar
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA
| | - Peng Zhang
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA
| | - Christian Rankl
- Keysight Technologies Austria GmbH, Mooslackengasse 17, 1190, Vienna, Austria
| | - Marion Holy
- Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090, Vienna, Austria
| | - Sonja Sucic
- Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090, Vienna, Austria
| | - Oliver Kudlacek
- Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090, Vienna, Austria
| | - Andreas Karner
- Institute for Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria.,Center for Advanced Bioanalysis, Gruberstrasse 40, 4020, Linz, Austria
| | - Walter Sandtner
- Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090, Vienna, Austria
| | - Thomas Stockner
- Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090, Vienna, Austria
| | - Hermann J Gruber
- Institute for Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria
| | - Michael Freissmuth
- Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090, Vienna, Austria
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore, MD, 21224, USA
| | - Harald H Sitte
- Center of Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse 13a, 1090, Vienna, Austria
| | - Peter Hinterdorfer
- Institute for Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria. .,Christian Doppler Laboratory for Nanoscopic Methods in Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020, Linz, Austria. .,Center for Advanced Bioanalysis, Gruberstrasse 40, 4020, Linz, Austria.
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36
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Andersen J, Ladefoged LK, Wang D, Kristensen TNB, Bang-Andersen B, Kristensen AS, Schiøtt B, Strømgaard K. Binding of the multimodal antidepressant drug vortioxetine to the human serotonin transporter. ACS Chem Neurosci 2015; 6:1892-900. [PMID: 26389667 DOI: 10.1021/acschemneuro.5b00225] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Selective inhibitors of the human serotonin transporter (hSERT) have been first-line treatment against depression for several decades. Recently, vortioxetine was approved as a new therapeutic option for the treatment of depression. Vortioxetine represents a new class of antidepressant drugs with a multimodal pharmacological profile that in addition to potent inhibition of hSERT include agonistic or antagonistic effects at different serotonin receptors. We used a combination of computational, chemical, and biological methods to decipher the molecular basis for high affinity binding of vortioxetine in hSERT. X-ray crystal structures of the bacterial amino acid transporter LeuT and the Drosophila melanogaster dopamine transporter were used to build homology models of hSERT. Comparative modeling and ligand docking suggest that vortioxetine can adopt several distinct binding modes within the central binding site of hSERT. To distinguish between the identified binding modes, we determined the effect of 57 functional hSERT point mutants on vortioxetine potency and characterized seven structurally related analogs of vortioxetine in a subset of the point mutants. This allowed us to determine the orientation of vortioxetine within the central binding site and showed that only one of the proposed binding modes is functionally relevant. The findings provide important new insight about the molecular basis for high affinity recognition of vortioxetine in hSERT, which is essential for future structure-based drug discovery of novel multimodal drugs with fine-tuned selectivity across different transporter and receptor proteins in the human brain.
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Affiliation(s)
- Jacob Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Lucy Kate Ladefoged
- Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary
Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade
140, DK-8000 Aarhus
C, Denmark
| | - Danyang Wang
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Trine N. Bjerre Kristensen
- Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary
Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade
140, DK-8000 Aarhus
C, Denmark
| | - Benny Bang-Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
- Lundbeck Research Denmark, H. Lundbeck A/S, Ottiliavej 9, DK-2500 Valby, Denmark
| | - Anders S. Kristensen
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Birgit Schiøtt
- Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary
Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Langelandsgade
140, DK-8000 Aarhus
C, Denmark
| | - Kristian Strømgaard
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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37
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Andersen J, Ringsted KB, Bang-Andersen B, Strømgaard K, Kristensen AS. Binding site residues control inhibitor selectivity in the human norepinephrine transporter but not in the human dopamine transporter. Sci Rep 2015; 5:15650. [PMID: 26503701 PMCID: PMC4621520 DOI: 10.1038/srep15650] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/01/2015] [Indexed: 02/08/2023] Open
Abstract
The transporters for norepinephrine and dopamine (NET and DAT, respectively) constitute the molecular targets for recreational drugs and therapeutics used in the treatment of psychiatric disorders. Despite a strikingly similar amino acid sequence and predicted topology between these transporters, some inhibitors display a high degree of selectivity between NET and DAT. Here, a systematic mutational analysis of non-conserved residues within the extracellular entry pathway and the high affinity binding site in NET and DAT was performed to examine their role for selective inhibitor recognition. Changing the six diverging residues in the central binding site of NET to the complementary residues in DAT transferred a DAT-like pharmacology to NET, showing that non-conserved binding site residues in NET are critical determinants for inhibitor selectivity. In contrast, changing the equivalent residues in the central site of DAT to the corresponding residues in NET had modest effects on the same inhibitors, suggesting that non-conserved binding site residues in DAT play a minor role for selective inhibitor recognition. Our data points towards distinct structural determinants governing inhibitor selectivity in NET and DAT, and provide important new insight into the molecular basis for NET/DAT selectivity of therapeutic and recreational drugs.
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Affiliation(s)
- Jacob Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, DK-2100 Copenhagen, Denmark
| | - Kristoffer B Ringsted
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, DK-2100 Copenhagen, Denmark
| | - Benny Bang-Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, DK-2100 Copenhagen, Denmark.,Lundbeck Research Denmark, H. Lundbeck A/S, Ottiliavej 9, DK-2500 Valby, Denmark
| | - Kristian Strømgaard
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, DK-2100 Copenhagen, Denmark
| | - Anders S Kristensen
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, DK-2100 Copenhagen, Denmark
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38
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Grouleff J, Ladefoged LK, Koldsø H, Schiøtt B. Monoamine transporters: insights from molecular dynamics simulations. Front Pharmacol 2015; 6:235. [PMID: 26528185 PMCID: PMC4607855 DOI: 10.3389/fphar.2015.00235] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 10/01/2015] [Indexed: 01/31/2023] Open
Abstract
The human monoamine transporters (MATs) facilitate the reuptake of the neurotransmitters serotonin, dopamine, and norepinephrine from the synaptic cleft. Imbalance in monoaminergic neurotransmission is linked to various diseases including major depression, attention deficit hyperactivity disorder, schizophrenia, and Parkinson's disease. Inhibition of the MATs is thus an important strategy for treatment of such diseases. The MATs are sodium-coupled transport proteins belonging to the neurotransmitter/Na(+) symporter (NSS) family, and the publication of the first high-resolution structure of a NSS family member, the bacterial leucine transporter LeuT, in 2005, proved to be a major stepping stone for understanding this family of transporters. Structural data allows for the use of computational methods to study the MATs, which in turn has led to a number of important discoveries. The process of substrate translocation across the membrane is an intrinsically dynamic process. Molecular dynamics simulations, which can provide atomistic details of molecular motion on ns to ms timescales, are therefore well-suited for studying transport processes. In this review, we outline how molecular dynamics simulations have provided insight into the large scale motions associated with transport of the neurotransmitters, as well as the presence of external and internal gates, the coupling between ion and substrate transport, and differences in the conformational changes induced by substrates and inhibitors.
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Affiliation(s)
- Julie Grouleff
- Center for Insoluble Protein Structures and Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University Aarhus, Denmark
| | - Lucy Kate Ladefoged
- Center for Insoluble Protein Structures and Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University Aarhus, Denmark
| | - Heidi Koldsø
- Department of Biochemistry, University of Oxford Oxford, UK
| | - Birgit Schiøtt
- Center for Insoluble Protein Structures and Interdisciplinary Nanoscience Center, Department of Chemistry, Aarhus University Aarhus, Denmark
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Mortensen OV, Kortagere S. Designing modulators of monoamine transporters using virtual screening techniques. Front Pharmacol 2015; 6:223. [PMID: 26483692 PMCID: PMC4586420 DOI: 10.3389/fphar.2015.00223] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 09/17/2015] [Indexed: 12/15/2022] Open
Abstract
The plasma-membrane monoamine transporters (MATs), including the serotonin (SERT), norepinephrine (NET) and dopamine (DAT) transporters, serve a pivotal role in limiting monoamine-mediated neurotransmission through the reuptake of their respective monoamine neurotransmitters. The transporters are the main target of clinically used psychostimulants and antidepressants. Despite the availability of several potent and selective MAT substrates and inhibitors the continuing need for therapeutic drugs to treat brain disorders involving aberrant monoamine signaling provides a compelling reason to identify novel ways of targeting and modulating the MATs. Designing novel modulators of MAT function have been limited by the lack of three dimensional structure information of the individual MATs. However, crystal structures of LeuT, a bacterial homolog of MATs, in a substrate-bound occluded, substrate-free outward-open, and an apo inward-open state and also with competitive and non-competitive inhibitors have been determined. In addition, several structures of the Drosophila DAT have also been resolved. Together with computational modeling and experimental data gathered over the past decade, these structures have dramatically advanced our understanding of several aspects of SERT, NET, and DAT transporter function, including some of the molecular determinants of ligand interaction at orthosteric substrate and inhibitor binding pockets. In addition progress has been made in the understanding of how allosteric modulation of MAT function can be achieved. Here we will review all the efforts up to date that has been made through computational approaches employing structural models of MATs to design small molecule modulators to the orthosteric and allosteric sites using virtual screening techniques.
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Affiliation(s)
- Ole V Mortensen
- Department of Pharmacology and Physiology, Drexel University College of Medicine , Philadelphia, PA, USA
| | - Sandhya Kortagere
- Department of Microbiology and Immunology, Drexel University College of Medicine , Philadelphia, PA, USA
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Koldsø H, Grouleff J, Schiøtt B. Insights to ligand binding to the monoamine transporters-from homology modeling to LeuBAT and dDAT. Front Pharmacol 2015; 6:208. [PMID: 26441663 PMCID: PMC4585151 DOI: 10.3389/fphar.2015.00208] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/07/2015] [Indexed: 11/20/2022] Open
Abstract
Understanding of drug binding to the human biogenic amine transporters (BATs) is essential to explain the mechanism of action of these pharmaceuticals but more importantly to be able to develop new and improved compounds to be used in the treatment of depression or drug addiction. Until recently no high resolution structure was available of the BATs and homology modeling was a necessity. Various studies have revealed experimentally validated binding modes of numerous ligands to the BATs using homology modeling. Here we examine and discuss the similarities between the binding models of substrates, antidepressants, psychostimulants, and mazindol in homology models of the human BATs and the recently published crystal structures of the Drosophila dopamine transporter and the engineered protein, LeuBAT. The comparison reveals that careful computational modeling combined with experimental data can be utilized to predict binding of molecules to proteins that agree very well with crystal structures.
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Affiliation(s)
- Heidi Koldsø
- Department of Biochemistry, University of Oxford , Oxford, UK ; inSPIN and iNANO Centers, Department of Chemistry, Aarhus University , Aarhus C, Denmark
| | - Julie Grouleff
- inSPIN and iNANO Centers, Department of Chemistry, Aarhus University , Aarhus C, Denmark
| | - Birgit Schiøtt
- inSPIN and iNANO Centers, Department of Chemistry, Aarhus University , Aarhus C, Denmark
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41
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Kastrinsky DB, Sangodkar J, Zaware N, Izadmehr S, Dhawan NS, Narla G, Ohlmeyer M. Reengineered tricyclic anti-cancer agents. Bioorg Med Chem 2015; 23:6528-34. [PMID: 26372073 DOI: 10.1016/j.bmc.2015.07.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/26/2015] [Accepted: 07/04/2015] [Indexed: 12/22/2022]
Abstract
The phenothiazine and dibenzazepine tricyclics are potent neurotropic drugs with a documented but underutilized anti-cancer side effect. Reengineering these agents (TFP, CPZ, CIP) by replacing the basic amine with a neutral polar functional group (e.g., RTC-1, RTC-2) abrogated their CNS effects as demonstrated by in vitro pharmacological assays and in vivo behavioral models. Further optimization generated several phenothiazines and dibenzazepines with improved anti-cancer potency, exemplified by RTC-5. This new lead demonstrated efficacy against a xenograft model of an EGFR driven cancer without the neurotropic effects exhibited by the parent molecules. Its effects were attributed to concomitant negative regulation of PI3K-AKT and RAS-ERK signaling.
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Affiliation(s)
- David B Kastrinsky
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mt. Sinai, 1425 Madison Avenue, New York, NY 10029, United States
| | - Jaya Sangodkar
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mt. Sinai, 1425 Madison Avenue, New York, NY 10029, United States
| | - Nilesh Zaware
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mt. Sinai, 1425 Madison Avenue, New York, NY 10029, United States
| | - Sudeh Izadmehr
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mt. Sinai, 1425 Madison Avenue, New York, NY 10029, United States
| | - Neil S Dhawan
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mt. Sinai, 1425 Madison Avenue, New York, NY 10029, United States
| | - Goutham Narla
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mt. Sinai, 1425 Madison Avenue, New York, NY 10029, United States; Department of Medicine, Institute for Transformative Molecular Medicine, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH 44106, United States
| | - Michael Ohlmeyer
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mt. Sinai, 1425 Madison Avenue, New York, NY 10029, United States.
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42
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Rannversson H, Wilson P, Kristensen KB, Sinning S, Kristensen AS, Strømgaard K, Andersen J. Importance of the Extracellular Loop 4 in the Human Serotonin Transporter for Inhibitor Binding and Substrate Translocation. J Biol Chem 2015; 290:14582-94. [PMID: 25903124 DOI: 10.1074/jbc.m114.629071] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Indexed: 12/20/2022] Open
Abstract
The serotonin transporter (SERT) terminates serotonergic neurotransmission by performing reuptake of released serotonin, and SERT is the primary target for antidepressants. SERT mediates the reuptake of serotonin through an alternating access mechanism, implying that a central substrate site is connected to both sides of the membrane by permeation pathways, of which only one is accessible at a time. The coordinated conformational changes in SERT associated with substrate translocation are not fully understood. Here, we have identified a Leu to Glu mutation at position 406 (L406E) in the extracellular loop 4 (EL4) of human SERT, which induced a remarkable gain-of-potency (up to >40-fold) for a range of SERT inhibitors. The effects were highly specific for L406E relative to six other mutations in the same position, including the closely related L406D mutation, showing that the effects induced by L406E are not simply charge-related effects. Leu(406) is located >10 Å from the central inhibitor binding site indicating that the mutation affects inhibitor binding in an indirect manner. We found that L406E decreased accessibility to a residue in the cytoplasmic pathway. The shift in equilibrium to favor a more outward-facing conformation of SERT can explain the reduced turnover rate and increased association rate of inhibitor binding we found for L406E. Together, our findings show that EL4 allosterically can modulate inhibitor binding within the central binding site, and substantiates that EL4 has an important role in controlling the conformational equilibrium of human SERT.
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Affiliation(s)
- Hafsteinn Rannversson
- From the Department of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen and
| | - Pamela Wilson
- From the Department of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen and
| | - Kristina Birch Kristensen
- the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, DK-8240 Risskov, Denmark
| | - Steffen Sinning
- the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, DK-8240 Risskov, Denmark
| | - Anders Skov Kristensen
- From the Department of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen and
| | - Kristian Strømgaard
- From the Department of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen and
| | - Jacob Andersen
- From the Department of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen and
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43
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Bjerregaard H, Severinsen K, Said S, Wiborg O, Sinning S. A dualistic conformational response to substrate binding in the human serotonin transporter reveals a high affinity state for serotonin. J Biol Chem 2015; 290:7747-55. [PMID: 25614630 DOI: 10.1074/jbc.m114.573477] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Serotonergic neurotransmission is modulated by the membrane-embedded serotonin transporter (SERT). SERT mediates the reuptake of serotonin into the presynaptic neurons. Conformational changes in SERT occur upon binding of ions and substrate and are crucial for translocation of serotonin across the membrane. Our understanding of these conformational changes is mainly based on crystal structures of a bacterial homolog in various conformations, derived homology models of eukaryotic neurotransmitter transporters, and substituted cysteine accessibility method of SERT. However, the dynamic changes that occur in the human SERT upon binding of ions, the translocation of substrate, and the role of cholesterol in this interplay are not fully elucidated. Here we show that serotonin induces a dualistic conformational response in SERT. We exploited the substituted cysteine scanning method under conditions that were sensitized to detect a more outward-facing conformation of SERT. We found a novel high affinity outward-facing conformational state of the human SERT induced by serotonin. The ionic requirements for this new conformational response to serotonin mirror the ionic requirements for translocation. Furthermore, we found that membrane cholesterol plays a role in the dualistic conformational response in SERT induced by serotonin. Our results indicate the existence of a subpopulation of SERT responding differently to serotonin binding than hitherto believed and that membrane cholesterol plays a role in this subpopulation of SERT.
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Affiliation(s)
- Henriette Bjerregaard
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark
| | - Kasper Severinsen
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark
| | - Saida Said
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark
| | - Ove Wiborg
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark
| | - Steffen Sinning
- From the Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skovagervej 2, DK-8240 Risskov, Denmark
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Pedersen AV, Andreassen TF, Loland CJ. A conserved salt bridge between transmembrane segments 1 and 10 constitutes an extracellular gate in the dopamine transporter. J Biol Chem 2014; 289:35003-14. [PMID: 25339174 DOI: 10.1074/jbc.m114.586982] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Neurotransmitter transporters play an important role in termination of synaptic transmission by mediating reuptake of neurotransmitter, but the molecular processes behind translocation are still unclear. The crystal structures of the bacterial homologue, LeuT, provided valuable insight into the structural and dynamic requirements for substrate transport. These structures support the existence of gating domains controlling access to a central binding site. On the extracellular side, access is controlled by the "thin gate" formed by an interaction between Arg-30 and Asp-404. In the human dopamine transporter (DAT), the corresponding residues are Arg-85 and Asp-476. Here, we present results supporting the existence of a similar interaction in DAT. The DAT R85D mutant has a complete loss of function, but the additional insertion of an arginine in opposite position (R85D/D476R), causing a charge reversal, results in a rescue of binding sites for the cocaine analogue [(3)H]CFT. Also, the coordination of Zn(2+) between introduced histidines (R85H/D476H) caused a ∼ 2.5-fold increase in [(3)H]CFT binding (Bmax). Importantly, Zn(2+) also inhibited [(3)H]dopamine transport in R85H/D476H, suggesting that a dynamic interaction is required for the transport process. Furthermore, cysteine-reactive chemistry shows that mutation of the gating residues causes a higher proportion of transporters to reside in the outward facing conformation. Finally, we show that charge reversal of the corresponding residues (R104E/E493R) in the serotonin transporter also rescues [(3)H](S)-citalopram binding, suggesting a conserved feature. Taken together, these data suggest that the extracellular thin gate is present in monoamine transporters and that a dynamic interaction is required for substrate transport.
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Affiliation(s)
- Anders V Pedersen
- From the Department of Neuroscience and Pharmacology, Molecular Neuropharmacology Laboratory, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Thorvald F Andreassen
- From the Department of Neuroscience and Pharmacology, Molecular Neuropharmacology Laboratory, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Claus J Loland
- From the Department of Neuroscience and Pharmacology, Molecular Neuropharmacology Laboratory, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
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45
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Jaworska A, Malek K. A comparison between adsorption mechanism of tricyclic antidepressants on silver nanoparticles and binding modes on receptors. Surface-enhanced Raman spectroscopy studies. J Colloid Interface Sci 2014; 431:117-24. [DOI: 10.1016/j.jcis.2014.05.060] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 05/26/2014] [Accepted: 05/29/2014] [Indexed: 11/21/2022]
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46
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Nolan TL, Geffert LM, Kolber BJ, Madura JD, Surratt CK. Discovery of novel-scaffold monoamine transporter ligands via in silico screening with the S1 pocket of the serotonin transporter. ACS Chem Neurosci 2014; 5:784-92. [PMID: 25003748 PMCID: PMC4176318 DOI: 10.1021/cn500133b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
![]()
Discovery of new inhibitors of the
plasmalemmal monoamine transporters
(MATs) continues to provide pharmacotherapeutic options for depression,
addiction, attention deficit disorders, psychosis, narcolepsy, and
Parkinson’s disease. The windfall of high-resolution MAT structural
information afforded by X-ray crystallography has enabled the construction
of credible computational models. Elucidation of lead compounds, creation
of compound structure–activity series, and pharmacologic testing
are staggering expenses that could be reduced by using a MAT computational
model for virtual screening (VS) of structural libraries containing
millions of compounds. Here, VS of the PubChem small molecule structural
database using the S1 (primary substrate) ligand pocket of a serotonin
transporter homology model yielded 19 prominent “hit”
compounds. In vitro pharmacology of these VS hits revealed four structurally
unique MAT substrate uptake inhibitors with high nanomolar affinity
at one or more of the three MATs. In vivo characterization of three
of these hits revealed significant activity in a mouse model of acute
depression at doses that did not elicit untoward locomotor effects.
This constitutes the first report of MAT inhibitor discovery using
exclusively the primary substrate pocket as a VS tool. Novel-scaffold
MAT inhibitors offer hope of new medications that lack the many classic
adverse effects of existing antidepressant drugs.
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Affiliation(s)
- Tammy L. Nolan
- Division of Pharmaceutical Sciences,
Mylan School of Pharmacy, ‡Departments of Chemistry
and Biochemistry, Center for Computational Sciences,
and §Department of Biological
Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
| | - Laura M. Geffert
- Division of Pharmaceutical Sciences,
Mylan School of Pharmacy, ‡Departments of Chemistry
and Biochemistry, Center for Computational Sciences,
and §Department of Biological
Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
| | - Benedict J. Kolber
- Division of Pharmaceutical Sciences,
Mylan School of Pharmacy, ‡Departments of Chemistry
and Biochemistry, Center for Computational Sciences,
and §Department of Biological
Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
| | - Jeffry D. Madura
- Division of Pharmaceutical Sciences,
Mylan School of Pharmacy, ‡Departments of Chemistry
and Biochemistry, Center for Computational Sciences,
and §Department of Biological
Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
| | - Christopher K. Surratt
- Division of Pharmaceutical Sciences,
Mylan School of Pharmacy, ‡Departments of Chemistry
and Biochemistry, Center for Computational Sciences,
and §Department of Biological
Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
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47
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Loland CJ. The use of LeuT as a model in elucidating binding sites for substrates and inhibitors in neurotransmitter transporters. Biochim Biophys Acta Gen Subj 2014; 1850:500-10. [PMID: 24769398 DOI: 10.1016/j.bbagen.2014.04.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 04/09/2014] [Accepted: 04/11/2014] [Indexed: 01/24/2023]
Abstract
BACKGROUND The mammalian neurotransmitter transporters are complex proteins playing a central role in synaptic transmission between neurons by rapid reuptake of neurotransmitters. The proteins which transport dopamine, noradrenaline and serotonin belong to the Neurotransmitter:Sodium Symporters (NSS). Due to their important role, dysfunctions are associated with several psychiatric and neurological diseases and they also serve as targets for a wide range of therapeutic and illicit drugs. Despite the central physiological and pharmacological importance, direct evidence on structure-function relationships on mammalian NSS proteins has so far been unsuccessful. The crystal structure of the bacterial NSS protein, LeuT, has been a turning point in structural investigations. SCOPE OF REVIEW To provide an update on what is known about the binding sites for substrates and inhibitors in the LeuT. The different binding modes and binding sites will be discussed with special emphasis on the possible existence of a second substrate binding site. It is the goal to give an insight into how investigations on ligand binding in LeuT have provided basic knowledge about transporter conformations and translocation mechanism which can pave the road for a deeper understanding of drug binding and function of the mammalian transporters. MAJOR CONCLUSIONS The LeuT is a suitable model for the structural investigation of NSS proteins including the possible location of drug binding sites. It is still debated whether the LeuT is a suitable model for the molecular mechanisms behind substrate translocation. GENERAL SIGNIFICANCE Structure and functional aspects of NSS proteins are central for understanding synaptic transmission. With the purification and crystallization of LeuT as well as the dopamine transporter from Drosophila melanogaster, the application of biophysical methods such as fluorescence spectroscopy, neutron- or x-ray scattering and NMR for understanding its function becomes increasingly available. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.
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Affiliation(s)
- Claus J Loland
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, The Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark.
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48
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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49
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Gabrielsen M, Kurczab R, Siwek A, Wolak M, Ravna AW, Kristiansen K, Kufareva I, Abagyan R, Nowak G, Chilmonczyk Z, Sylte I, Bojarski AJ. Identification of novel serotonin transporter compounds by virtual screening. J Chem Inf Model 2014; 54:933-43. [PMID: 24521202 PMCID: PMC3982395 DOI: 10.1021/ci400742s] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The serotonin (5-hydroxytryptamine, 5-HT) transporter (SERT) plays an essential role in the termination of serotonergic neurotransmission by removing 5-HT from the synaptic cleft into the presynaptic neuron. It is also of pharmacological importance being targeted by antidepressants and psychostimulant drugs. Here, five commercial databases containing approximately 3.24 million drug-like compounds have been screened using a combination of two-dimensional (2D) fingerprint-based and three-dimensional (3D) pharmacophore-based screening and flexible docking into multiple conformations of the binding pocket detected in an outward-open SERT homology model. Following virtual screening (VS), selected compounds were evaluated using in vitro screening and full binding assays and an in silico hit-to-lead (H2L) screening was performed to obtain analogues of the identified compounds. Using this multistep VS/H2L approach, 74 active compounds, 46 of which had K(i) values of ≤1000 nM, belonging to 16 structural classes, have been identified, and multiple compounds share no structural resemblance with known SERT binders.
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Affiliation(s)
- Mari Gabrielsen
- Medical Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, UiT, The Arctic University of Norway , 9037 Tromsø, Norway
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50
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Andersen J, Stuhr-Hansen N, Zachariassen LG, Koldsø H, Schiøtt B, Strømgaard K, Kristensen AS. Molecular basis for selective serotonin reuptake inhibition by the antidepressant agent fluoxetine (Prozac). Mol Pharmacol 2014; 85:703-14. [PMID: 24516100 DOI: 10.1124/mol.113.091249] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inhibitors of the serotonin transporter (SERT) are widely used antidepressant agents, but the structural mechanism for inhibitory activity and selectivity over the closely related norepinephrine transporter (NET) is not well understood. Here we use a combination of chemical, biological, and computational methods to decipher the molecular basis for high-affinity recognition in SERT and selectivity over NET for the prototypical antidepressant drug fluoxetine (Prozac; Eli Lilly, Indianapolis, IN). We show that fluoxetine binds within the central substrate site of human SERT, in agreement with recent X-ray crystal structures of LeuBAT, an engineered monoamine-like version of the bacterial amino acid transporter LeuT. However, the binding orientation of fluoxetine is reversed in our experimentally supported model compared with the LeuBAT structures, emphasizing the need for careful experimental verification when extrapolating findings from crystal structures of bacterial transporters to human relatives. We find that the selectivity of fluoxetine and nisoxetine, a NET selective structural congener of fluoxetine, is controlled by residues in different regions of the transporters, indicating a complex mechanism for selective recognition of structurally similar compounds in SERT and NET. Our findings add important new information on the molecular basis for SERT/NET selectivity of antidepressants, and provide the first assessment of the potential of LeuBAT as a model system for antidepressant binding in human transporters, which is essential for future structure-based drug development of antidepressant drugs with fine-tuned transporter selectivity.
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Affiliation(s)
- Jacob Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (J.A., N.S.-H., L.G.Z., K.S., A.S.K.); and Center for Insoluble Structures (inSPIN) and Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Aarhus, Denmark (H.K., B.S.)
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