Novel and High Affinity Fluorescent Ligands for the Serotonin Transporter Based on (<i>S</i>)-Citalopram

Kumar, Vivek; Rahbek-Clemmensen, Troels; Billesbølle, Christian B.; Jørgensen, Trine N.; Gether, Ulrik; Newman, Amy Hauck

doi:10.1021/ml5000806

Cited by 19 publications

(32 citation statements)

References 14 publications

(27 reference statements)

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“…Compound ( S )- 4 was synthesized according to General Method A using ( S )- 5 49 (82 mg, 0.26 mmol) and quinoline-3-carboxylic acid (44 mg, 0.26 mmol). The crude product was purified by column chromatography as described for General Method A to give ( S )- 4 (42 mg, 34% yield) as a light brown solid.…”

Section: Experimental Methodsmentioning

confidence: 99%

Toward Understanding the Structural Basis of Partial Agonism at the Dopamine D₃ Receptor

et al. 2017

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Both dopamine D3 receptor (D3R) partial agonists and antagonists have been implicated as potential medications for substance use disorders. In contrast to antagonists, partial agonists may cause fewer side effects since they maintain some dopaminergic tone and may be less disruptive to normal neuronal functions. Here, we report three sets of 4-phenylpiperazine stereoisomers that differ considerably in efficacy: the (R)-enantiomers are antagonists/weak partial agonists whereas the (S)-enantiomers are much more efficacious. To investigate the structural basis of partial agonism, we performed comparative microsecond-scale molecular dynamics simulations starting from the inactive state of D3R in complex with these enantiomers. Analysis of the simulation results reveals common structural rearrangements near the ligand binding site induced by the bound (S)-enantiomers, but not by the (R)-enantiomers, that are features of partially activated receptor conformations. These receptor models bound with partial agonists may be useful for structure-based design of compounds with tailored efficacy profiles.

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Section: Experimental Methodsmentioning

confidence: 99%

Toward Understanding the Structural Basis of Partial Agonism at the Dopamine D₃ Receptor

et al. 2017

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“…An alkyne‐modified 5‐aminomethyl analogue of the pure S ‐ or the R ‐enantiomer of CIT was covalently conjugated onto the AFM cantilever tip (Figure a; Supporting Information, Figure S1) via an azido‐terminated flexible polyethylene glycol (PEG) linker through click chemistry (Supporting Information, Methods). Single molecular force measurements were conducted by performing force‐distance cycles on living CHOK1 cells that stably express human SERT.…”

Section: Figurementioning

confidence: 99%

Nanopharmacological Force Sensing to Reveal Allosteric Coupling in Transporter Binding Sites

et al. 2015

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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 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. Our 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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“…An alkyne-modified5 -aminomethyl analogue [19] of the pure S-orthe R-enantiomerofCIT wascovalentlyconjugated onto theA FM cantilever tip ( Figure 1a;S upportingInformation,F igureS1) viaa na zido-terminatedf lexible polyethylene glycol (PEG)l inkert hrough clickc hemistry (Supporting Information, Methods).Singlemolecular forcemeasurements were conductedb yp erformingf orce-distancec ycleso nl iving CHOK1c ells that stably expressh uman SERT.T he S-o rR-CIT-adornedA FM cantilever tipw as loweredt owards the cellular surfacet oa llow forS ERTb inding andw as subsequentlymoved upwards. When theCIT moiety on theAFM tip boundt oSERTont he cell surface, ap ulling forced eveloped during theu pward movementb etween thet ip andc ell membrane,c ausing thec antilevert ob endd ownwards (Fig-ure1b).The pullingforce increased to acriticalvalue untilthe bond betweenSERTand CITwas ruptured (unbinding force).…”

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confidence: 99%

Nanopharmacological Force Sensing to Reveal Allosteric Coupling in Transporter Binding Sites

et al. 2015

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Controversy regardingt he number and function of ligand binding sites in neurotransmitter/sodium symporters arose from conflicting data in crystal structures and molecular pharmacology.Here,wehave designed novel tools for atomic force microscopyt hat directly measure the interaction forces between the serotonin transporter (SERT) and the S-and Renantiomers of citalopram on the single molecule level. This approach is based on force spectroscopy, whichallows for the extraction of dynamic information under physiological conditions thus inaccessible via X-ray crystallography.T wo distinct populations of characteristic binding strengths of citalopram to SERT were revealed in Na + -containing buffer. In contrast, in Li + -containing buffer,S ERT showed only low force interactions.C onversely,t he vestibular mutant SERT-G402H merely displayed the high force population. These observations provide physical evidence for the existence of two binding sites in SERTwhen accessed in aphysiological context. Competition experiments revealed that these two sites are allosterically coupled and exert reciprocal modulation.

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Novel and High Affinity Fluorescent Ligands for the Serotonin Transporter Based on (S)-Citalopram

Cited by 19 publications

References 14 publications

Toward Understanding the Structural Basis of Partial Agonism at the Dopamine D₃ Receptor

Toward Understanding the Structural Basis of Partial Agonism at the Dopamine D₃ Receptor

Nanopharmacological Force Sensing to Reveal Allosteric Coupling in Transporter Binding Sites

Nanopharmacological Force Sensing to Reveal Allosteric Coupling in Transporter Binding Sites

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Novel and High Affinity Fluorescent Ligands for the Serotonin Transporter Based on (S)-Citalopram

Cited by 19 publications

References 14 publications

Toward Understanding the Structural Basis of Partial Agonism at the Dopamine D3 Receptor

Toward Understanding the Structural Basis of Partial Agonism at the Dopamine D3 Receptor

Nanopharmacological Force Sensing to Reveal Allosteric Coupling in Transporter Binding Sites

Nanopharmacological Force Sensing to Reveal Allosteric Coupling in Transporter Binding Sites

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Toward Understanding the Structural Basis of Partial Agonism at the Dopamine D₃ Receptor

Toward Understanding the Structural Basis of Partial Agonism at the Dopamine D₃ Receptor